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Thor KB, Marson L, Katofiasc MA, Ricca DJ, Burgard EC. Recent Developments in On-Demand Voiding Therapies. J Pharmacol Exp Ther 2024; 390:302-317. [PMID: 38641354 PMCID: PMC11338280 DOI: 10.1124/jpet.123.002073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 03/28/2024] [Accepted: 03/29/2024] [Indexed: 04/21/2024] Open
Abstract
One cannot survive without regularly urinating and defecating. People with neurologic injury (spinal cord injury, traumatic brain injury, stroke) or disease (multiple sclerosis, Parkinson's disease, spina bifida) and many elderly are unable to voluntarily initiate voiding. The great majority of them require bladder catheters to void urine and "manual bowel programs" with digital rectal stimulation and manual extraction to void stool. Catheter-associated urinary tract infections frequently require hospitalization, whereas manual bowel programs are time consuming (1 to 2 hours) and stigmatizing and cause rectal pain and discomfort. Laxatives and enemas produce defecation, but onset and duration are unpredictable, prolonged, and difficult to control, which can produce involuntary defecation and fecal incontinence. Patients with spinal cord injury (SCI) consider recovery of bladder and bowel function a higher priority than recovery of walking. Bladder and bowel dysfunction are a top reason for institutionalization of elderly. Surveys indicate that convenience, rapid onset and short duration, reliability and predictability, and efficient voiding are priorities of SCI individuals. Despite the severe, unmet medical need, there is no literature regarding on-demand, rapid-onset, short-duration, drug-induced voiding therapies. This article provides in-depth discussion of recent discovery and development of two candidates for on-demand voiding therapies. The first, [Lys3,Gly8,-R-γ-lactam-Leu9]-NKA(3-10) (DTI-117), a neurokinin2 receptor agonist, induces both urination and defecation after systemic administration. The second, capsaicin (DTI-301), is a transient receptor potential cation channel subfamily V member 1 (TRPV1) receptor agonist that induces defecation after intrarectal administration. The review also presents clinical studies of a combination drug therapy administered via iontophoresis and preclinical studies of neuromodulation devices that induce urination and defecation. SIGNIFICANCE STATEMENT: A safe and effective, on-demand, rapid-onset, short-duration, drug-induced, voiding therapy could eliminate or reduce need for bladder catheters, manual bowel programs, and colostomies in patient populations that are unable to voluntarily initiate voiding. People with spinal injury place more importance on restoring bladder and bowel control than restoring their ability to walk. This paradigm-changing therapy would reduce stigmatism and healthcare costs while increasing convenience and quality of life.
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Affiliation(s)
- Karl B Thor
- Dignify Therapeutics, LLC, Durham, North Carolina
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2
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Fardadi M, Leiter JC, Lu DC, Iwasaki T. Model-based analysis of the acute effects of transcutaneous magnetic spinal cord stimulation on micturition after spinal cord injury in humans. PLoS Comput Biol 2024; 20:e1012237. [PMID: 38950067 PMCID: PMC11244836 DOI: 10.1371/journal.pcbi.1012237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 07/12/2024] [Accepted: 06/07/2024] [Indexed: 07/03/2024] Open
Abstract
AIM After spinal cord injuries (SCIs), patients may develop either detrusor-sphincter dyssynergia (DSD) or urinary incontinence, depending on the level of the spinal injury. DSD and incontinence reflect the loss of coordinated neural control among the detrusor muscle, which increases bladder pressure to facilitate urination, and urethral sphincters and pelvic floor muscles, which control the bladder outlet to restrict or permit bladder emptying. Transcutaneous magnetic stimulation (TMS) applied to the spinal cord after SCI reduced DSD and incontinence. We defined, within a mathematical model, the minimum neuronal elements necessary to replicate neurogenic dysfunction of the bladder after a SCI and incorporated into this model the minimum additional neurophysiological features sufficient to replicate the improvements in bladder function associated with lumbar TMS of the spine in patients with SCI. METHODS We created a computational model of the neural circuit of micturition based on Hodgkin-Huxley equations that replicated normal bladder function. We added interneurons and increased network complexity to reproduce dysfunctional micturition after SCI, and we increased the density and complexity of interactions of both inhibitory and excitatory lumbar spinal interneurons responsive to TMS to provide a more diverse set of spinal responses to intrinsic and extrinsic activation of spinal interneurons that remains after SCI. RESULTS The model reproduced the re-emergence of a spinal voiding reflex after SCI. When we investigated the effect of monophasic and biphasic TMS at two frequencies applied at or below T10, the model replicated the improved coordination between detrusor and external urethral sphincter activity that has been observed clinically: low-frequency TMS (1 Hz) within the model normalized control of voiding after SCI, whereas high-frequency TMS (30 Hz) enhanced urine storage. CONCLUSION Neuroplasticity and increased complexity of interactions among lumbar interneurons, beyond what is necessary to simulate normal bladder function, must be present in order to replicate the effects of SCI on control of micturition, and both neuronal and network modifications of lumbar interneurons are essential to understand the mechanisms whereby TMS reduced bladder dysfunction after SCI.
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Affiliation(s)
- Mahshid Fardadi
- Department of Mechanical Engineering, University of California, Los Angeles, California, United States of America
| | - J. C. Leiter
- White River Junction VA Medical Center, White River Junction, Vermont, United States of America
| | - Daniel C. Lu
- Department of Neurosurgery, University of California, Los Angeles, California, United States of America
| | - Tetsuya Iwasaki
- Department of Mechanical Engineering, University of California, Los Angeles, California, United States of America
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Giannotti A, Musco S, Miragliotta V, Lazzarini G, Pirone A, Briganti A, Verardo C, Bernini F, Del Popolo G, Micera S. Swine Pudendal Nerve as a Model for Neuromodulation Studies to Restore Lower Urinary Tract Dysfunction. Int J Mol Sci 2024; 25:855. [PMID: 38255927 PMCID: PMC10815560 DOI: 10.3390/ijms25020855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 01/08/2024] [Accepted: 01/08/2024] [Indexed: 01/24/2024] Open
Abstract
Lower urinary tract dysfunction, such as incontinence or urinary retention, is one of the leading consequences of neurological diseases. This significantly impacts the quality of life for those affected, with implications extending not only to humans but also to clinical veterinary care. Having motor and sensory fibers, the pudendal nerve is an optimal candidate for neuromodulation therapies using bidirectional intraneural prostheses, paving the way towards the restoration of a more physiological urination cycle: bladder state can be detected from recorded neural signals, then an electrical current can be injected to the nerve based on the real-time need of the bladder. To develop such prostheses and investigate this novel approach, animal studies are still required since the morphology of the target nerve is fundamental to optimizing the prosthesis design. This study aims to describe the porcine pudendal nerve as a model for neuromodulation studies aiming at restoring lower urinary tract dysfunction. Five male farm pigs were involved in the study. First, a surgical procedure to access the porcine pudendal nerve without muscle resection was developed. Then, an intraneural interface was implanted to confirm the presence of fibers innervating the external urethral sphincter by measuring its electromyographic activity. Finally, the morphophysiology of the porcine pudendal nerve at the level of surgical exposure was described by using histological and immunohistochemical characterization. This analysis confirmed the fasciculate nature of the nerve and the presence of mixed fibers with a spatial and functional organization. These achievements pave the way for further pudendal neuromodulation studies by using a clinically relevant animal model with the potential for translating the findings into clinical applications.
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Affiliation(s)
- Alice Giannotti
- The BioRobotics Institute and Department of Excellence in Robotics and AI, Scuola Superiore Sant’Anna, 56127 Pisa, Italy; (A.G.); (C.V.)
| | - Stefania Musco
- Neuro-Urology Department, Careggi University Hospital, 50134 Firenze, Italy; (S.M.); (G.D.P.)
| | - Vincenzo Miragliotta
- Department of Veterinary Sciences, University of Pisa, 56124 Pisa, Italy; (V.M.); (G.L.); (A.P.); (A.B.)
| | - Giulia Lazzarini
- Department of Veterinary Sciences, University of Pisa, 56124 Pisa, Italy; (V.M.); (G.L.); (A.P.); (A.B.)
| | - Andrea Pirone
- Department of Veterinary Sciences, University of Pisa, 56124 Pisa, Italy; (V.M.); (G.L.); (A.P.); (A.B.)
| | - Angela Briganti
- Department of Veterinary Sciences, University of Pisa, 56124 Pisa, Italy; (V.M.); (G.L.); (A.P.); (A.B.)
| | - Claudio Verardo
- The BioRobotics Institute and Department of Excellence in Robotics and AI, Scuola Superiore Sant’Anna, 56127 Pisa, Italy; (A.G.); (C.V.)
| | - Fabio Bernini
- BioMedLab, Scuola Superiore Sant’Anna, 56127 Pisa, Italy;
| | - Giulio Del Popolo
- Neuro-Urology Department, Careggi University Hospital, 50134 Firenze, Italy; (S.M.); (G.D.P.)
| | - Silvestro Micera
- The BioRobotics Institute and Department of Excellence in Robotics and AI, Scuola Superiore Sant’Anna, 56127 Pisa, Italy; (A.G.); (C.V.)
- Bertarelli Foundation Chair in Translational NeuroEngineering, Center for Neuroprosthetics and Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
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Hokanson JA, Langdale CL, Grill WM. Pathways and parameters of sacral neuromodulation in rats. Am J Physiol Renal Physiol 2023; 325:F757-F769. [PMID: 37795537 PMCID: PMC10874681 DOI: 10.1152/ajprenal.00123.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 09/06/2023] [Accepted: 10/01/2023] [Indexed: 10/06/2023] Open
Abstract
The stimulation paradigm for sacral neuromodulation has remained largely unchanged since its inception. We sought to determine, in rats, whether stimulation-induced increases in bladder capacity correlated with the proportion of sensory pudendal (PudS) neurons at each stimulated location (L6, S1). If supported, this finding could guide the choice of stimulation side (left/right) and level (S2, S3, S4) in humans. Unexpectedly, we observed that acute stimulation at clinically relevant (low) amplitudes [1-1.5 × motor threshold (Tm)], did not increase bladder capacity, regardless of stimulus location (L6 or S1). More importantly for the ability to test our hypothesis, there was little anatomic variation, and S1 infrequently contributed nerve fibers to the PudS nerve. During mapping studies we noticed that large increases in PudS nerve activation occurred at amplitudes exceeding 2Tm. Thus, additional cystometric studies were conducted, this time with stimulation of the L6-S1 trunk, to examine further the relationship between stimulation amplitude and cystometric parameters. Stimulation at 1Tm to 6Tm evoked increases in bladder capacity and decreases in voiding efficiency that mirrored those produced by PudS nerve stimulation. Many animal studies involving electrical stimulation of nerves of the lower urinary tract use stimulation amplitudes that exceed those used clinically (∼1Tm). Our results confirm that high amplitudes generate immediate changes in cystometric parameters; however, the relationship to low-amplitude chronic stimulation in humans remains unclear. Additional studies are needed to understand changes that occur with chronic stimulation, how these changes relate to therapeutic outcomes, and the contribution of specific nerve fibers to these changes.NEW & NOTEWORTHY Acute low-amplitude electrical stimulation of sacral nerve (sacral neuromodulation) did not increase bladder capacity in anesthetized CD, obese-prone, or obese-resistant rats. Increasing stimulation amplitude correlated with increases in bladder capacity and pudendal sensory nerve recruitment. It is unclear how the high-amplitude acute stimulation that is commonly used in animal experiments to generate immediate effects compares mechanistically to the chronic low-amplitude stimulation used clinically.
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Affiliation(s)
- James A Hokanson
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States
- Joint Department of Biomedical Engineering, Medical College of Wisconsin, Marquette University, Milwaukee, Wisconsin, United States
| | - Christopher L Langdale
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States
- Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina, United States
- Department of Neurobiology, Duke University, Durham, North Carolina, United States
- Department of Neurosurgery, Duke University, Durham, North Carolina, United States
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5
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Jantz MK, Gopinath C, Kumar R, Chin C, Wong L, Ogren JI, Fisher LE, McLaughlin BL, Gaunt RA. High-density spinal cord stimulation selectively activates lower urinary tract nerves. J Neural Eng 2022; 19:066014. [PMID: 36343359 PMCID: PMC9855651 DOI: 10.1088/1741-2552/aca0c2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 11/07/2022] [Indexed: 11/09/2022]
Abstract
Objective.Epidural spinal cord stimulation (SCS) is a potential intervention to improve limb and autonomic functions, with lumbar stimulation improving locomotion and thoracic stimulation regulating blood pressure. Here, we asked whether sacral SCS could be used to target the lower urinary tract (LUT) and used a high-density epidural electrode array to test whether individual electrodes could selectively recruit LUT nerves.Approach. We placed a high-density epidural SCS array on the dorsal surface of the sacral spinal cord and cauda equina of anesthetized cats and recorded the stimulation-evoked activity from nerve cuffs on the pelvic, pudendal and sciatic nerves.Main results. Here we show that sacral SCS evokes responses in nerves innervating the bladder and urethra and that these nerves can be activated selectively. Sacral SCS always recruited the pelvic and pudendal nerves and selectively recruited both of these nerves in all but one animal. Individual branches of the pudendal nerve were always recruited as well. Electrodes that selectively recruited specific peripheral nerves were spatially clustered on the arrays, suggesting anatomically organized sensory pathways.Significance.This selective recruitment demonstrates a mechanism to directly modulate bladder and urethral function through known reflex pathways, which could be used to restore bladder and urethral function after injury or disease.
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Affiliation(s)
- Maria K Jantz
- Rehab Neural Engineering Labs, University of Pittsburgh, Pittsburgh, PA, United States of America
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States of America
- Center for the Neural Basis of Cognition, Pittsburgh, PA, United States of America
| | - Chaitanya Gopinath
- Rehab Neural Engineering Labs, University of Pittsburgh, Pittsburgh, PA, United States of America
- Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Ritesh Kumar
- Rehab Neural Engineering Labs, University of Pittsburgh, Pittsburgh, PA, United States of America
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States of America
- Center for the Neural Basis of Cognition, Pittsburgh, PA, United States of America
| | - Celine Chin
- Micro-Leads Inc., Somerville, MA, United States of America
| | - Liane Wong
- Micro-Leads Inc., Somerville, MA, United States of America
| | - John I Ogren
- Micro-Leads Inc., Somerville, MA, United States of America
| | - Lee E Fisher
- Rehab Neural Engineering Labs, University of Pittsburgh, Pittsburgh, PA, United States of America
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States of America
- Center for the Neural Basis of Cognition, Pittsburgh, PA, United States of America
- Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, PA, United States of America
- Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA, United States of America
| | | | - Robert A Gaunt
- Rehab Neural Engineering Labs, University of Pittsburgh, Pittsburgh, PA, United States of America
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States of America
- Center for the Neural Basis of Cognition, Pittsburgh, PA, United States of America
- Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, PA, United States of America
- Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA, United States of America
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6
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Wang SY, Qiu Q, Shen X. Effect of Pudendal Nerve Block on the Prevention of Postoperative Bladder Spasm and Catheter-Related Bladder Discomfort in Male Patients Undergoing Transurethral Holmium Laser Enucleation of the Prostate. Clin Interv Aging 2022; 17:1729-1738. [DOI: 10.2147/cia.s384612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 11/21/2022] [Indexed: 12/02/2022] Open
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7
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Hoey RF, Medina-Aguiñaga D, Khalifa F, Ugiliweneza B, Wang D, Zdunowski S, Fell J, Naglah A, El-Baz AS, Herrity AN, Harkema SJ, Hubscher CH. Thoracolumbar epidural stimulation effects on bladder and bowel function in uninjured and chronic transected anesthetized rats. Sci Rep 2022; 12:2137. [PMID: 35136100 PMCID: PMC8826941 DOI: 10.1038/s41598-022-06011-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 01/18/2022] [Indexed: 11/09/2022] Open
Abstract
Pre-clinical studies have shown that spinal cord epidural stimulation (scES) at the level of pelvic and pudendal nerve inputs/outputs (L5-S1) alters storage and/or emptying functions of both the bladder and bowel. The current mapping experiments were conducted to investigate scES efficacy at the level of hypogastric nerve inputs/outputs (T13-L2) in male and female rats under urethane anesthesia. As found with L5-S1 scES, T13-L2 scES at select frequencies and intensities of stimulation produced an increase in inter-contraction interval (ICI) in non-injured female rats but a short-latency void in chronic T9 transected rats, as well as reduced rectal activity in all groups. However, the detrusor pressure during the lengthened ICI (i.e., urinary hold) remained at a low pressure and was not elevated as seen with L5-S1 scES, an effect that's critical for translation to the clinic as high fill pressures can damage the kidneys. Furthermore, T13-L2 scES was shown to stimulate voiding post-transection by increasing bladder activity while also directly inhibiting the external urethral sphincter, a pattern necessary to overcome detrusor-sphincter dyssynergia. Additionally, select scES parameters at T13-L2 also increased distal colon activity in all groups. Together, the current findings suggest that optimization of scES for bladder and bowel will likely require multiple electrode cohorts at different locations that target circuitries coordinating sympathetic, parasympathetic and somatic outputs.
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Affiliation(s)
- Robert F Hoey
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, KY, USA.,Physical Medicine and Rehabilitation Department, MetroHealth Rehabilitation Institute of Ohio, Cleveland, OH, USA
| | - Daniel Medina-Aguiñaga
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, KY, USA
| | - Fahmi Khalifa
- Bioengineering Department, University of Louisville J. B. Speed School of Engineering, Louisville, KY, USA
| | - Beatrice Ugiliweneza
- Department of Neurological Surgery, University of Louisville School of Medicine, Louisville, KY, USA.,Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA.,Department of Health Management and Systems Science, School of Public Health and Information Science, University of Louisville, Louisville, KY, USA
| | - Dengzhi Wang
- Department of Neurological Surgery, University of Louisville School of Medicine, Louisville, KY, USA.,Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA
| | - Sharon Zdunowski
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA
| | - Jason Fell
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, KY, USA
| | - Ahmed Naglah
- Bioengineering Department, University of Louisville J. B. Speed School of Engineering, Louisville, KY, USA
| | - Ayman S El-Baz
- Bioengineering Department, University of Louisville J. B. Speed School of Engineering, Louisville, KY, USA
| | - April N Herrity
- Department of Neurological Surgery, University of Louisville School of Medicine, Louisville, KY, USA.,Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA
| | - Susan J Harkema
- Department of Neurological Surgery, University of Louisville School of Medicine, Louisville, KY, USA.,Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA
| | - Charles H Hubscher
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, KY, USA. .,Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA.
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Shen JD, Chen SJ, Chen HY, Chiu KY, Chen YH, Chen WC. Review of Animal Models to Study Urinary Bladder Function. BIOLOGY 2021; 10:biology10121316. [PMID: 34943231 PMCID: PMC8698391 DOI: 10.3390/biology10121316] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 12/07/2021] [Accepted: 12/09/2021] [Indexed: 12/24/2022]
Abstract
Simple Summary The treatment of urinary bladder dysfunction requires the knowledge of bladder function, which involves physiology, pathology, and even psychology. Several animal models are available to study a variety of bladder disorders. These models include animals from rodents, such as mice and rats, to nonhuman primates, such as rabbits, felines, canines, pigs, and mini pigs. This review adapted animal models to study bladder function according to facility, priority, and disease. Abstract The urinary bladder (UB) serves as a storage and elimination organ for urine. UB dysfunction can cause multiple symptoms of failure to store urine or empty the bladder, e.g., incontinence, frequent urination, and urinary retention. Treatment of these symptoms requires knowledge on bladder function, which involves physiology, pathology, and even psychology. There is no ideal animal model for the study of UB function to understand and treat associated disorders, as the complexity in humans differs from that of other species. However, several animal models are available to study a variety of other bladder disorders. Such models include animals from rodents to nonhuman primates, such as mice, rats, rabbits, felines, canines, pigs, and mini pigs. For incontinence, vaginal distention might mimic birth trauma and can be measured based on leak point pressure. Using peripheral and central models, inflammation, bladder outlet obstruction, and genetic models facilitated the study of overactive bladder. However, the larger the animal model, the more difficult the study is, due to the associated animal ethics issues, laboratory facility, and budget. This review aims at facilitating adapted animal models to study bladder function according to facility, priority, and disease.
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Affiliation(s)
- Jing-Dung Shen
- Division of Urology, Department of Surgery, Taichung Armed Forces General Hospital, Taichung 41168, Taiwan;
- National Defense Medical Center, Taipei 11490, Taiwan
- Graduate Institute of Integrated Medicine, College of Chinese Medicine, China Medical University, Taichung 40402, Taiwan;
| | - Szu-Ju Chen
- Division of Urology, Department of Surgery, Taichung Veterans General Hospital, Taichung 40705, Taiwan; (S.-J.C.); (K.-Y.C.)
| | - Huey-Yi Chen
- Graduate Institute of Integrated Medicine, College of Chinese Medicine, China Medical University, Taichung 40402, Taiwan;
- Department of Obstetrics and Gynecology, Department of Medical Research, Department of Urology, China Medical University Hospital, Taichung 40447, Taiwan
| | - Kun-Yuan Chiu
- Division of Urology, Department of Surgery, Taichung Veterans General Hospital, Taichung 40705, Taiwan; (S.-J.C.); (K.-Y.C.)
| | - Yung-Hsiang Chen
- Graduate Institute of Integrated Medicine, College of Chinese Medicine, China Medical University, Taichung 40402, Taiwan;
- Department of Obstetrics and Gynecology, Department of Medical Research, Department of Urology, China Medical University Hospital, Taichung 40447, Taiwan
- Department of Psychology, College of Medical and Health Science, Asia University, Taichung 41354, Taiwan
- Correspondence: (Y.-H.C.); (W.-C.C.)
| | - Wen-Chi Chen
- Graduate Institute of Integrated Medicine, College of Chinese Medicine, China Medical University, Taichung 40402, Taiwan;
- Department of Obstetrics and Gynecology, Department of Medical Research, Department of Urology, China Medical University Hospital, Taichung 40447, Taiwan
- Correspondence: (Y.-H.C.); (W.-C.C.)
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Cracchiolo M, Ottaviani MM, Panarese A, Strauss I, Vallone F, Mazzoni A, Micera S. Bioelectronic medicine for the autonomic nervous system: clinical applications and perspectives. J Neural Eng 2021; 18. [PMID: 33592597 DOI: 10.1088/1741-2552/abe6b9] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 02/16/2021] [Indexed: 12/11/2022]
Abstract
Bioelectronic medicine (BM) is an emerging new approach for developing novel neuromodulation therapies for pathologies that have been previously treated with pharmacological approaches. In this review, we will focus on the neuromodulation of autonomic nervous system (ANS) activity with implantable devices, a field of BM that has already demonstrated the ability to treat a variety of conditions, from inflammation to metabolic and cognitive disorders. Recent discoveries about immune responses to ANS stimulation are the laying foundation for a new field holding great potential for medical advancement and therapies and involving an increasing number of research groups around the world, with funding from international public agencies and private investors. Here, we summarize the current achievements and future perspectives for clinical applications of neural decoding and stimulation of the ANS. First, we present the main clinical results achieved so far by different BM approaches and discuss the challenges encountered in fully exploiting the potential of neuromodulatory strategies. Then, we present current preclinical studies aimed at overcoming the present limitations by looking for optimal anatomical targets, developing novel neural interface technology, and conceiving more efficient signal processing strategies. Finally, we explore the prospects for translating these advancements into clinical practice.
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Affiliation(s)
- Marina Cracchiolo
- The BioRobotics Institute and Department of Excellence in Robotics & AI, The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Matteo Maria Ottaviani
- The BioRobotics Institute and Department of Excellence in Robotics & AI, The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Alessandro Panarese
- The BioRobotics Institute and Department of Excellence in Robotics & AI, The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Ivo Strauss
- The BioRobotics Institute and Department of Excellence in Robotics & AI, The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Fabio Vallone
- The BioRobotics Institute and Department of Excellence in Robotics & AI, The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Alberto Mazzoni
- The BioRobotics Institute and Department of Excellence in Robotics & AI, The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Silvestro Micera
- The BioRobotics Institute and Department of Excellence in Robotics & AI, The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy.,Bertarelli Foundation Chair in Translational NeuroEngineering, Centre for Neuroprosthetics and Institute of Bioengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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10
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Yousefpour A, Erfanian A. A general framework for automatic closed-loop control of bladder voiding induced by intraspinal microstimulation in rats. Sci Rep 2021; 11:3424. [PMID: 33564019 PMCID: PMC7873267 DOI: 10.1038/s41598-021-82933-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 01/27/2021] [Indexed: 12/13/2022] Open
Abstract
Individuals with spinal cord injury or neurological disorders have problems in voiding function due to the dyssynergic contraction of the urethral sphincter. Here, we introduce a closed-loop control of intraspinal microstimulation (ISMS) for efficient bladder voiding. The strategy is based on asynchronous two-electrode ISMS with combined pulse-amplitude and pulse-frequency modulation without requiring rhizotomy, neurotomy, or high-frequency blocking. Intermittent stimulation is alternately applied to the two electrodes that are implanted in the S2 lateral ventral horn and S1 dorsal gray commissure, to excite the bladder motoneurons and to inhibit the urethral sphincter motoneurons. Asynchronous stimulation would lead to reduce the net electric field and to maximize the selective stimulation. The proposed closed-loop system attains a highly voiding efficiency of 77.2-100%, with an average of 91.28 ± 8.4%. This work represents a promising approach to the development of a natural and robust motor neuroprosthesis device for restoring bladder functions.
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Affiliation(s)
- Abolhasan Yousefpour
- Department of Biomedical Engineering, School of Electrical Engineering, Iran Neural Technology Research Center, Iran University of Science and Technology (IUST), Tehran, Iran
| | - Abbas Erfanian
- Department of Biomedical Engineering, School of Electrical Engineering, Iran Neural Technology Research Center, Iran University of Science and Technology (IUST), Tehran, Iran.
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Hoey RF, Medina-Aguiñaga D, Khalifa F, Ugiliweneza B, Zdunowski S, Fell J, Naglah A, El-Baz AS, Herrity AN, Harkema SJ, Hubscher CH. Bladder and bowel responses to lumbosacral epidural stimulation in uninjured and transected anesthetized rats. Sci Rep 2021; 11:3268. [PMID: 33558526 PMCID: PMC7870824 DOI: 10.1038/s41598-021-81822-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 01/12/2021] [Indexed: 01/09/2023] Open
Abstract
Spinal cord epidural stimulation (scES) mapping at L5-S1 was performed to identify parameters for bladder and bowel inhibition and/or contraction. Using spinally intact and chronic transected rats of both sexes in acute urethane-anesthetized terminal preparations, scES was systematically applied using a modified Specify 5-6-5 (Medtronic) electrode during bladder filling/emptying cycles while recording bladder and colorectal pressures and external urethral and anal sphincter electromyography activity. The results indicate frequency-dependent effects on void volume, micturition, bowel peristalsis, and sphincter activity just above visualized movement threshold intensities that differed depending upon neurological intactness, with some sex-dependent differences. Thereafter, a custom-designed miniature 15-electrode array designed for greater selectivity was tested and exhibited the same frequency-dependent urinary effects over a much smaller surface area without any concurrent movements. Thus, select activation of autonomic nervous system circuitries with scES is a promising neuromodulation approach for expedient translation to individuals with SCI and potentially other neurologic disorders.
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Affiliation(s)
- Robert F Hoey
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, MDR, 511 S. Floyd St., Room 111, Louisville, KY, 40202, USA
| | - Daniel Medina-Aguiñaga
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, MDR, 511 S. Floyd St., Room 111, Louisville, KY, 40202, USA
| | - Fahmi Khalifa
- Bioengineering Department, University of Louisville J. B. Speed School of Engineering, Louisville, KY, USA
| | - Beatrice Ugiliweneza
- Department of Neurological Surgery, University of Louisville School of Medicine, Louisville, KY, USA
| | - Sharon Zdunowski
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA
| | - Jason Fell
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, MDR, 511 S. Floyd St., Room 111, Louisville, KY, 40202, USA
| | - Ahmed Naglah
- Bioengineering Department, University of Louisville J. B. Speed School of Engineering, Louisville, KY, USA
| | - Ayman S El-Baz
- Bioengineering Department, University of Louisville J. B. Speed School of Engineering, Louisville, KY, USA
| | - April N Herrity
- Department of Neurological Surgery, University of Louisville School of Medicine, Louisville, KY, USA
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA
| | - Susan J Harkema
- Department of Neurological Surgery, University of Louisville School of Medicine, Louisville, KY, USA
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA
| | - Charles H Hubscher
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, MDR, 511 S. Floyd St., Room 111, Louisville, KY, 40202, USA.
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA.
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Frequency-Dependent Effects on Bladder Reflex by Saphenous Nerve Stimulation and a Possible Action Mechanism of Tibial Nerve Stimulation in Cats. Int Neurourol J 2021; 25:128-136. [PMID: 33561917 PMCID: PMC8255824 DOI: 10.5213/inj.2040304.152] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 08/23/2020] [Indexed: 02/07/2023] Open
Abstract
Purpose The present study determined the effects of saphenous nerve stimulation (SNS) at different stimulation frequencies on bladder reflex and explored a possible action mechanism of tibial nerve stimulation (TNS) on bladder activity in cats. Methods Two bipolar nerve cuff electrodes were implanted on the saphenous nerve and the contralateral tibial nerve in 13 cats, respectively. Multiple cystometrograms were obtained to determine the effects of single SNS at different frequencies and that of combined SNS and TNS on the micturition reflex by infusing normal saline. Results SNS at 1 Hz significantly reduced the bladder capacity (BC) to 59.8%±7.7% and 59.3%±5.8% of the control level at the intensity threshold (T) and 2T, respectively (P<0.05), while that at 20 Hz significantly increased the BC to 130.6%±4.2% of the control level at 6T (P<0.05). The TNS and SNS at 20 Hz did not significantly change the BCs at 1T (P>0.05), while combined stimulation at 1T significantly increased the BC to 122.7%±1.9% of the control level and induced an inhibitory effect which was similar to that TNS at 2T. Conclusions The current study revealed that SNS reduced and increased BC depending on different stimulation frequencies. The combined SNS and TNS maximized the clinical efficacy at a low intensity. Also, SNS may be a potential therapeutic mechanism of TNS.
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State-dependent bioelectronic interface to control bladder function. Sci Rep 2021; 11:314. [PMID: 33431964 PMCID: PMC7801663 DOI: 10.1038/s41598-020-79493-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 12/09/2020] [Indexed: 11/23/2022] Open
Abstract
Electrical stimulation therapies to promote bladder filling and prevent incontinence deliver continuous inhibitory stimulation, even during bladder emptying. However, continuous inhibitory stimulation that increases bladder capacity (BC) can reduce the efficiency of subsequent voiding (VE). Here we demonstrate that state-dependent stimulation, with different electrical stimulation parameters delivered during filling and emptying can increase both BC and VE relative to continuous stimulation in rats and cats of both sexes. We show that continuous 10 Hz pudendal nerve stimulation increased BC (120–180% of control) but decreased VE (12–71%, relative to control). In addition to increasing BC, state-dependent stimulation in both rats and cats increased VE (280–759% relative to continuous stimulation); motor bursting in cats increased VE beyond the control (no stimulation) condition (males: 323%; females: 161%). These results suggest that a bioelectronic bladder pacemaker can treat complex voiding disorders, including both incontinence and retention, which paradoxically are often present in the same individual.
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Geramipour A, Danziger ZC. Sensitivity of urethral flow-evoked voiding reflexes decline with age in the rat: insights into age-related underactive bladder. Am J Physiol Renal Physiol 2020; 318:F1430-F1440. [DOI: 10.1152/ajprenal.00475.2019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The prevalence of underactive bladder (UAB) increases with age, suggesting a link between age-related processes and lower urinary tract (LUT) symptoms; however, the underlying mechanisms of age-related UAB are poorly understood. Understanding how aging affects LUT reflexes may help in the development of new treatments by identifying mechanistic targets. In this work, we studied the relationship between age and systems-level function of the LUT and tested the hypothesis that aging is related to weakening of reflexes that control voiding. Three groups of anesthetized female rats, young (4–7 mo old), mature (11–14 mo old), and old (18–24 mo old), were used to quantify the effect of aging on LUT reflexes. A double-lumen catheter enabled us to control the bladder volume and urethral flow rate independently, under quasi-isovolumetric bladder conditions. We systematically investigated the reflex bladder contractions evoked by combinations of rates of urethral infusion and bladder fill volumes as a function of age. Urethral infusion with the same flow rate evoked bladder contractions (via the augmenting reflex) in old animals less often than in younger animals. Furthermore, old animals needed more fluid in their bladders (relative to their bladder capacity) before urethra flow-evoked bladder contractions could be triggered at all, suggesting a delay in the switch of the LUT to “voiding mode.” Old rats also showed longer and weaker bladder contractions than young or mature rats. Taken together, this suggests there is an age-related functional weakening and loss of sensitivity in LUT reflexes, which may contribute to age-related UAB symptoms.
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Affiliation(s)
- Arezoo Geramipour
- Department of Biomedical Engineering, Florida International University, Miami, Florida
| | - Zachary C. Danziger
- Department of Biomedical Engineering, Florida International University, Miami, Florida
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15
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Guiho T, Azevedo-Coste C, Andreu D, Delleci C, Bauchet L, Vignes JR, Guiraud D. Functional Selectivity of Lumbosacral Stimulation: Methodological Approach and Pilot Study to Assess Visceral Function in Pigs. IEEE Trans Neural Syst Rehabil Eng 2018; 26:2165-2178. [DOI: 10.1109/tnsre.2018.2871763] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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16
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Excitatory and inhibitory effects of stimulation of sacral dorsal root ganglion on bladder reflex in cats. Int Urol Nephrol 2018; 50:2179-2186. [DOI: 10.1007/s11255-018-2004-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Accepted: 10/04/2018] [Indexed: 01/23/2023]
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17
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Peh WYX, Mogan R, Thow XY, Chua SM, Rusly A, Thakor NV, Yen SC. Novel Neurostimulation of Autonomic Pelvic Nerves Overcomes Bladder-Sphincter Dyssynergia. Front Neurosci 2018; 12:186. [PMID: 29618971 PMCID: PMC5871706 DOI: 10.3389/fnins.2018.00186] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 03/06/2018] [Indexed: 12/25/2022] Open
Abstract
The disruption of coordination between smooth muscle contraction in the bladder and the relaxation of the external urethral sphincter (EUS) striated muscle is a common issue in dysfunctional bladders. It is a significant challenge to overcome for neuromodulation approaches to restore bladder control. Bladder-sphincter dyssynergia leads to undesirably high bladder pressures, and poor voiding outcomes, which can pose life-threatening secondary complications. Mixed pelvic nerves are potential peripheral targets for stimulation to treat dysfunctional bladders, but typical electrical stimulation of pelvic nerves activates both the parasympathetic efferent pathway to excite the bladder, as well as the sensory afferent pathway that causes unwanted sphincter contractions. Thus, a novel pelvic nerve stimulation paradigm is required. In anesthetized female rats, we combined a low frequency (10 Hz) stimulation to evoke bladder contraction, and a more proximal 20 kHz stimulation of the pelvic nerve to block afferent activation, in order to produce micturition with reduced bladder-sphincter dyssynergia. Increasing the phase width of low frequency stimulation from 150 to 300 μs alone was able to improve voiding outcome significantly. However, low frequency stimulation of pelvic nerves alone evoked short latency (19.9–20.5 ms) dyssynergic EUS responses, which were abolished with a non-reversible proximal central pelvic nerve cut. We demonstrated that a proximal 20 kHz stimulation of pelvic nerves generated brief onset effects at lower current amplitudes, and was able to either partially or fully block the short latency EUS responses depending on the ratio of the blocking to stimulation current. Our results indicate that ratios >10 increased the efficacy of blocking EUS contractions. Importantly, we also demonstrated for the first time that this combined low and high frequency stimulation approach produced graded control of the bladder, while reversibly blocking afferent signals that elicited dyssynergic EUS contractions, thus improving voiding by 40.5 ± 12.3%. Our findings support advancing pelvic nerves as a suitable neuromodulation target for treating bladder dysfunction, and demonstrate the feasibility of an alternative method to non-reversible nerve transection and sub-optimal intermittent stimulation methods to reduce dyssynergia.
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Affiliation(s)
- Wendy Yen Xian Peh
- Singapore Institute for Neurotechnology, National University of Singapore, Singapore, Singapore
| | - Roshini Mogan
- Singapore Institute for Neurotechnology, National University of Singapore, Singapore, Singapore
| | - Xin Yuan Thow
- Singapore Institute for Neurotechnology, National University of Singapore, Singapore, Singapore
| | - Soo Min Chua
- Singapore Institute for Neurotechnology, National University of Singapore, Singapore, Singapore
| | - Astrid Rusly
- Singapore Institute for Neurotechnology, National University of Singapore, Singapore, Singapore
| | - Nitish V Thakor
- Singapore Institute for Neurotechnology, National University of Singapore, Singapore, Singapore.,Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore.,Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore.,Biomedical Engineering, School of Medicine, Johns Hopkins University, Baltimore, MD, United States
| | - Shih-Cheng Yen
- Singapore Institute for Neurotechnology, National University of Singapore, Singapore, Singapore.,Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
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Wang Z, Liao L, Deng H, Li X, Chen G. The inhibitory effect of sacral dorsal root ganglion stimulation on nociceptive and nonnociceptive bladder reflexes in cats. World J Urol 2018; 36:829-836. [DOI: 10.1007/s00345-018-2198-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 01/19/2018] [Indexed: 01/23/2023] Open
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Hokanson JA, Langdale CL, Sridhar A, Grill WM. Stimulation of the sensory pudendal nerve increases bladder capacity in the rat. Am J Physiol Renal Physiol 2017; 314:F543-F550. [PMID: 29141938 DOI: 10.1152/ajprenal.00373.2017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Pudendal nerve stimulation is a promising treatment approach for lower urinary tract dysfunction, including symptoms of overactive bladder. Despite some promising clinical studies, there remain many unknowns as to how best to stimulate the pudendal nerve to maximize therapeutic efficacy. We quantified changes in bladder capacity and voiding efficiency during single-fill cystometry in response to electrical stimulation of the sensory branch of the pudendal nerve in urethane-anesthetized female Wistar rats. Increases in bladder capacity were dependent on both stimulation amplitude and rate. Stimulation that produced increases in bladder capacity also led to reductions in voiding efficiency. Also, there was a stimulation carryover effect, and increases in bladder capacity persisted during several nonstimulated trials following stimulated trials. Intravesically administered PGE2 reduced bladder capacity, producing a model of overactive bladder (OAB), and sensory pudendal nerve stimulation again increased bladder capacity but also reduced voiding efficiency. This study serves as a basis for future studies that seek to maximize the therapeutic efficacy of sensory pudendal nerve stimulation for the symptoms of OAB.
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Affiliation(s)
- James A Hokanson
- Department of Biomedical Engineering, Duke University , Durham, North Carolina
| | | | - Arun Sridhar
- Bioelectronics R&D, Galvani, Stevenage , United Kingdom
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University , Durham, North Carolina.,Department of Electrical and Computer Engineering, Duke University , Durham, North Carolina.,Department of Neurobiology, Duke University , Durham, North Carolina.,Department of Surgery, Duke University , Durham, North Carolina
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20
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McGee MJ, Swan BD, Danziger ZC, Amundsen CL, Grill WM. Multiple Reflex Pathways Contribute to Bladder Activation by Intraurethral Stimulation in Persons With Spinal Cord Injury. Urology 2017; 109:210-215. [PMID: 28801220 DOI: 10.1016/j.urology.2017.07.041] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 07/22/2017] [Accepted: 07/28/2017] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To measure the urodynamic effects of electrical co-stimulation of 2 individual sites in the proximal and distal urethra in persons with spinal cord injury (SCI). This work was motivated by preclinical findings that selective co-stimulation of the cranial urethral sensory nerve and the dorsal genital nerve, which innervate the proximal and distal portions of the urethra, respectively, increased reflex bladder activation and voiding efficiency. MATERIALS AND METHODS Electrical co-stimulation of urethral afferents was conducted in persons with chronic SCI during urodynamics. The effects of different frequencies of intraurethral stimulation at multiple urethral locations on bladder pressure and pelvic floor electromyographic activity were measured. RESULTS Electromyographic activity indicated that multiple reflex pathways were recruited through stimulation that contributed to bladder activation. The size of reflex bladder contractions evoked by stimulation was dependent on stimulation location or reflex activated and stimulation frequency. CONCLUSION Pudendal nerve afferents are a promising target to restore lost bladder control, as stimulation with different frequencies may be used to treat urinary incontinence and increase continent volumes or to generate stimulation-evoked bladder contractions for on-demand voiding. This work identified that co-stimulation of multiple afferent reflex pathways can enhance activation of spinal circuits and may enable improved bladder emptying in SCI when stimulation of a single pathway is not sufficient.
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Affiliation(s)
- Meredith J McGee
- Department of Biomedical Engineering, Duke University, Durham, NC
| | - Brandon D Swan
- Department of Biomedical Engineering, Duke University, Durham, NC
| | | | - Cindy L Amundsen
- Department of Obstetrics and Gynecology, Division of Urogynecology and Reconstructive Pelvic Surgery, Duke University Medical Center, Durham, NC
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, NC; Department of Neurobiology, Duke University, Durham, NC; Department of Neurosurgery, Duke University, Durham, NC; Department of Electrical and Computer Engineering, Duke University, Durham, NC.
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21
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Danziger ZC, Grill WM. Sensory feedback from the urethra evokes state-dependent lower urinary tract reflexes in rat. J Physiol 2017; 595:5687-5698. [PMID: 28612936 DOI: 10.1113/jp274191] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 06/06/2017] [Indexed: 01/31/2023] Open
Abstract
KEY POINTS The lower urinary tract is regulated by reflexes responsible for maintaining continence and producing efficient voiding. It is unclear how sensory information from the bladder and urethra engages differential, state-dependent reflexes to either maintain continence or promote voiding. Using a new in vivo experimental approach, we quantified how sensory information from the bladder and urethra are integrated to switch reflex responses to urethral sensory feedback from maintaining continence to producing voiding. The results demonstrate how sensory information regulates state-dependent reflexes in the lower urinary tract and contribute to our understanding of the pathophysiology of urinary retention and incontinence where sensory feedback may engage these reflexes inappropriately. ABSTRACT Lower urinary tract reflexes are mediated by peripheral afferents from the bladder (primarily in the pelvic nerve) and the urethra (in the pudendal and pelvic nerves) to maintain continence or initiate micturition. If fluid enters the urethra at low bladder volumes, reflexes relax the bladder and evoke external urethral sphincter (EUS) contraction (guarding reflex) to maintain continence. Conversely, urethral flow at high bladder volumes, excites the bladder (micturition reflex) and relaxes the EUS (augmenting reflex). We conducted measurements in a urethane-anaesthetized in vivo rat preparation to characterize systematically the reflexes evoked by fluid flow through the urethra. We used a novel preparation to manipulate sensory feedback from the bladder and urethra independently by controlling bladder volume and urethral flow. We found a distinct bladder volume threshold (74% of bladder capacity) above which flow-evoked bladder contractions were 252% larger and evoked phasic EUS activation 2.6 times as often as responses below threshold, clearly demonstrating a discrete transition between continence (guarding) and micturition (augmenting) reflexes. Below this threshold urethral flow evoked tonic EUS activity, indicative of the guarding reflex, that was proportional to the urethral flow rate. These results demonstrate the complementary roles of sensory feedback from the bladder and urethra in regulating reflexes in the lower urinary tract that depend on the state of the bladder. Understanding the neural control of functional reflexes and how they are mediated by sensory information in the bladder and urethra will open new opportunities, especially in neuromodulation, to treat pathologies of the lower urinary tract.
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Affiliation(s)
- Zachary C Danziger
- Department of Biomedical Engineering, Florida International University, Miami, FL, USA
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, NC, USA.,Department of Neurobiology, Duke University, Durham, NC, USA
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Khurram A, Ross SE, Sperry ZJ, Ouyang A, Stephan C, Jiman AA, Bruns TM. Chronic monitoring of lower urinary tract activity via a sacral dorsal root ganglia interface. J Neural Eng 2017; 14:036027. [PMID: 28322213 DOI: 10.1088/1741-2552/aa6801] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVE Our goal is to develop an interface that integrates chronic monitoring of lower urinary tract (LUT) activity with stimulation of peripheral pathways. APPROACH Penetrating microelectrodes were implanted in sacral dorsal root ganglia (DRG) of adult male felines. Peripheral electrodes were placed on or in the pudendal nerve, bladder neck and near the external urethral sphincter. Supra-pubic bladder catheters were implanted for saline infusion and pressure monitoring. Electrode and catheter leads were enclosed in an external housing on the back. Neural signals from microelectrodes and bladder pressure of sedated or awake-behaving felines were recorded under various test conditions in weekly sessions. Electrodes were also stimulated to drive activity. MAIN RESULTS LUT single- and multi-unit activity was recorded for 4-11 weeks in four felines. As many as 18 unique bladder pressure single-units were identified in each experiment. Some channels consistently recorded bladder afferent activity for up to 41 d, and we tracked individual single-units for up to 23 d continuously. Distension-evoked and stimulation-driven (DRG and pudendal) bladder emptying was observed, during which LUT sensory activity was recorded. SIGNIFICANCE This chronic implant animal model allows for behavioral studies of LUT neurophysiology and will allow for continued development of a closed-loop neuroprosthesis for bladder control.
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Affiliation(s)
- Abeer Khurram
- Biomedical Engineering Department, University of Michigan, Ann Arbor, MI, United States of America. Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States of America
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Moazzam Z, Duke AR, Yoo PB. Posterior tibial nerve stimulation using a wirelessly powered system in anesthetized cats. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2016:4459-4462. [PMID: 28269268 DOI: 10.1109/embc.2016.7591717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Posterior Tibial Nerve Stimulation (PTNS) is an effective overactive bladder (OAB) therapy where electrical pulses are typically delivered once per week in a 12-week stimulation regime. While the mechanism of action remains unknown, effective long-term delivery of PTNS has recently become a subject of concern. To this end, a multi-contact electrode was surgically placed in the hind limb region of anesthetized cats to (1) investigate the feasibility of using a wirelessly powered system to stimulate PTN afferents and (2) characterize implant-driven effects of stimulation frequency on modulating bladder activity. Using an isovolumetric model, short-duration, supra-threshold stimulation trials were applied with frequencies ranging from 2-20 Hz. The results provide first pre-clinical evidence of frequency-dependent modulation of bladder function supporting the use of a novel therapeutic approach that can be clinically translated to potentially address multiple symptoms of lower urinary tract system.
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Neuromodulation of the neural circuits controlling the lower urinary tract. Exp Neurol 2016; 285:182-189. [PMID: 27381425 DOI: 10.1016/j.expneurol.2016.06.034] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Revised: 06/30/2016] [Accepted: 06/30/2016] [Indexed: 01/01/2023]
Abstract
The inability to control timely bladder emptying is one of the most serious challenges among the many functional deficits that occur after a spinal cord injury. We previously demonstrated that electrodes placed epidurally on the dorsum of the spinal cord can be used in animals and humans to recover postural and locomotor function after complete paralysis and can be used to enable voiding in spinal rats. In the present study, we examined the neuromodulation of lower urinary tract function associated with acute epidural spinal cord stimulation, locomotion, and peripheral nerve stimulation in adult rats. Herein we demonstrate that electrically evoked potentials in the hindlimb muscles and external urethral sphincter are modulated uniquely when the rat is stepping bipedally and not voiding, immediately pre-voiding, or when voiding. We also show that spinal cord stimulation can effectively neuromodulate the lower urinary tract via frequency-dependent stimulation patterns and that neural peripheral nerve stimulation can activate the external urethral sphincter both directly and via relays in the spinal cord. The data demonstrate that the sensorimotor networks controlling bladder and locomotion are highly integrated neurophysiologically and behaviorally and demonstrate how these two functions are modulated by sensory input from the tibial and pudental nerves. A more detailed understanding of the high level of interaction between these networks could lead to the integration of multiple neurophysiological strategies to improve bladder function. These data suggest that the development of strategies to improve bladder function should simultaneously engage these highly integrated networks in an activity-dependent manner.
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Langdale CL, Grill WM. Phasic activation of the external urethral sphincter increases voiding efficiency in the rat and the cat. Exp Neurol 2016; 285:173-181. [PMID: 27235934 DOI: 10.1016/j.expneurol.2016.05.030] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 04/29/2016] [Accepted: 05/23/2016] [Indexed: 10/21/2022]
Abstract
OBJECTIVE Electrical stimulation of the pudendal nerve (PN) is a potential therapy for bladder dysfunction, but voiding efficiency (VE) produced by PN stimulation appears limited to 60-70%. We conducted experiments in rats and cats to investigate the hypothesis that introduction of artificial phasic bursting activity of the external urethral sphincter (EUS) would enhance VE under conditions where such activity was absent. MATERIALS AND METHODS Cystometry experiments were conducted in 17 urethane anesthetized female Sprague-Dawley rats and 4 α-chloralose anesthetized male cats. The effects of phasic stimulation of the pudendal motor branch on VE were quantified in intact conditions, following bilateral transection of the motor branch of the PN, and following subsequent bilateral transection of the sensory branch of the PN. RESULTS Artificial phasic bursting activity in the EUS generated by electrical stimulation of the motor branch of the PN increased VE in both rats and cats. Subsequent transection of the sensory branch of the PN abolished the increased VE elicited by phasic stimulation in both rats and cats. CONCLUSIONS Artificial phasic EUS bursting restored efficient voiding in rats. Introduction of artificial phasic bursting in cats, which normally exhibit EUS relaxation while voiding, was also effective in promoting efficient voiding. In both species phasic EUS activity increased voiding efficiency via activation of pudendal sensory pathways. These results provide further insight into the function of phasic EUS activity in efficient voiding and highlight a novel approach to increase VE generated by pudendal afferent nerve stimulation.
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Affiliation(s)
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, NC, USA; Department of Electrical and Computer Engineering, Duke University, Durham, NC, USA; Department of Neurobiology, Duke University, Durham, NC, USA; Department of Surgery, Duke University, Durham, NC, USA.
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26
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Ju YH, Liao LM. Electrical stimulation of dog pudendal nerve regulates the excitatory pudendal-to-bladder reflex. Neural Regen Res 2016; 11:676-81. [PMID: 27212934 PMCID: PMC4870930 DOI: 10.4103/1673-5374.180757] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Pudendal nerve plays an important role in urine storage and voiding. Our hypothesis is that a neuroprosthetic device placed in the pudendal nerve trunk can modulate bladder function after suprasacral spinal cord injury. We had confirmed the inhibitory pudendal-to-bladder reflex by stimulating either the branch or the trunk of the pudendal nerve. This study explored the excitatory pudendal-to-bladder reflex in beagle dogs, with intact or injured spinal cord, by electrical stimulation of the pudendal nerve trunk. The optimal stimulation frequency was approximately 15-25 Hz. This excitatory effect was dependent to some extent on the bladder volume. We conclude that stimulation of the pudendal nerve trunk is a promising method to modulate bladder function.
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Affiliation(s)
- Yan-He Ju
- Department of Urology, China Rehabilitation Research Center, Beijing, China; School of Rahabilitation Medicine, Capital Medical University, Beijing, China; Center of Neural Injury and Repair, Beijing Institute for Brain Disorders, Beijing, China
| | - Li-Min Liao
- Department of Urology, China Rehabilitation Research Center, Beijing, China; School of Rahabilitation Medicine, Capital Medical University, Beijing, China; Center of Neural Injury and Repair, Beijing Institute for Brain Disorders, Beijing, China
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Moazzam Z, Duke AR, Yoo PB. Inhibition and Excitation of Bladder Function by Tibial Nerve Stimulation Using a Wirelessly Powered Implant: An Acute Study in Anesthetized Cats. J Urol 2016; 196:926-33. [PMID: 27154823 DOI: 10.1016/j.juro.2016.04.077] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/26/2016] [Indexed: 10/21/2022]
Abstract
PURPOSE Tibial nerve stimulation is a minimally invasive neuromodulation treatment of overactive bladder. However, in addition to our limited understanding of the underlying mechanisms, there are also questions regarding the long-term delivery of tibial nerve stimulation therapy in patients. We aimed to characterize the effects of stimulation frequency using a wirelessly powered implantable stimulation device. METHODS AND MATERIALS Six α-chloralose anesthetized adult male cats were used in this study. A multicontact lead was surgically implanted subcutaneously in the hind limb and used to stimulate the tibial nerve. Using an isovolumetric bladder a short duration of electrical pulses was applied at amplitudes 3 times the motor threshold and at frequencies from 2 to 20 Hz. RESULTS Implant driven stimulation of the tibial nerve resulted in frequency dependent activation of bladder reflexes. Low frequency tibial nerve stimulation (2 Hz) consistently evoked excitatory responses (mean ± SE 32.9% ± 3.8%). In contrast, higher frequency tibial nerve stimulation (6 to 20 Hz) inhibited bladder function (overall mean 14.9% ± 2.4%). Although low foot motor thresholds were achieved at initial implantation (mean 0.83 ± 0.05 mA), a notable elevation in threshold amplitude was observed 5 hours after implantation. CONCLUSIONS To our knowledge this study provides the first evidence of frequency dependent modulation of bladder function in anesthetized cats. The inhibitory influence of tibial nerve stimulation at frequencies above 6 Hz transitioned to an excitatory effect at 2 Hz. Taken together these preclinical data support the feasibility of using a wirelessly powered implantable device to potentially modulate bladder function in patients.
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Affiliation(s)
- Zainab Moazzam
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | | | - Paul B Yoo
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario, Canada.
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McGee MJ, Grill WM. Modeling the spinal pudendo-vesical reflex for bladder control by pudendal afferent stimulation. J Comput Neurosci 2016; 40:283-96. [PMID: 26968615 DOI: 10.1007/s10827-016-0597-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 01/25/2016] [Accepted: 02/23/2016] [Indexed: 01/13/2023]
Abstract
Electrical stimulation of the pudendal nerve (PN) is a promising approach to restore continence and micturition following bladder dysfunction resulting from neurological disease or injury. Although the pudendo-vesical reflex and its physiological properties are well established, there is limited understanding of the specific neural mechanisms that mediate this reflex. We sought to develop a computational model of the spinal neural network that governs the reflex bladder response to PN stimulation. We implemented and validated a neural network architecture based on previous neuroanatomical and electrophysiological studies. Using synaptically-connected integrate and fire model neurons, we created a network model with realistic spiking behavior. The model produced expected sacral parasympathetic nucleus (SPN) neuron firing rates from prescribed neural inputs and predicted bladder activation and inhibition with different frequencies of pudendal afferent stimulation. In addition, the model matched experimental results from previous studies of temporal patterns of pudendal afferent stimulation and selective pharmacological blockade of inhibitory neurons. The frequency- and pattern-dependent effects of pudendal afferent stimulation were determined by changes in firing rate of spinal interneurons, suggesting that neural network interactions at the lumbosacral level can mediate the bladder response to different frequencies or temporal patterns of pudendal afferent stimulation. Further, the anatomical structure of excitatory and inhibitory interneurons in the network model was necessary and sufficient to reproduce the critical features of the pudendo-vesical reflex, and this model may prove useful to guide development of novel, more effective electrical stimulation techniques for bladder control.
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Affiliation(s)
- Meredith J McGee
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, NC, USA. .,Department of Neurobiology, Duke University, Durham, NC, USA. .,Department of Electrical and Computer Engineering, Duke University, Durham, NC, USA. .,Department of Surgery, Duke University, Durham, NC, USA.
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Shiraz AN, Leaker B, Demosthenous A. Optimization of a wearable pudendal nerve stimulator using computational models. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2015:3395-8. [PMID: 26737021 DOI: 10.1109/embc.2015.7319121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
After spinal cord injury, lower urinary tract functions may be disrupted. Trans-rectal stimulation of the pudendal nerve may enable patients to regain these functions via minimally invasive means. Using a finite element model of a wearable trans-rectal stimulator in the pelvic region, and a computational model of mammalian nerve fiber, various electrode configurations and the corresponding required current levels were studied. A configuration requiring considerably lower current level than previously reported was identified. For this configuration, the strength-duration curve was simulated and the effect of different stimulus waveforms on the required current was studied. In addition, the study examined whether a multi-electrode device could selectively activate different terminal branches of the pudendal nerve.
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McGee MJ, Grill WM. Temporal pattern of stimulation modulates reflex bladder activation by pudendal nerve stimulation. Neurourol Urodyn 2015; 35:882-887. [PMID: 26147580 DOI: 10.1002/nau.22822] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 06/10/2015] [Indexed: 11/08/2022]
Abstract
AIMS Reflex bladder activation and inhibition by electrical stimulation of pudendal nerve (PN) afferents is a promising approach to restore control of bladder function in persons with lower urinary tract dysfunction caused by disease or injury. The objective of this work was to determine whether bladder activation evoked by pudendal afferent stimulation was dependent on the temporal pattern of stimulation, and whether specific temporal patterns of stimulation produced larger bladder contractions than constant frequency stimulation. METHODS The mean and maximum contraction pressures evoked by different temporal patterns of stimulation of the dorsal genital branch of the pudendal nerve were measured under isovolumetric conditions in α-chloralose anesthetized cats. A computational model of the spinal neural network mediating the pudendo-vesical reflex was used to understand the mechanisms of different bladder responses to patterned stimulation. RESULTS The pattern of stimulation significantly affected the magnitude of evoked bladder contractions; several temporal patterns were as effective as regular stimulation, but no pattern evoked larger bladder contractions. Random patterns and patterns with pauses, burst-like activity, or high frequency components evoked significantly smaller bladder contractions, supporting the use of regular frequency stimulation in the development of neural prosthetic approaches for bladder control. CONCLUSIONS These results reveal that the bladder response to pudendal afferent stimulation is dependent on the pattern, as well as the frequency, of stimulation. The computational model revealed that the effects of patterned pudendal afferent stimulation were determined by the dynamic properties of excitatory and inhibitory interneurons in the lumbosacral spinal cord. Neurourol. Urodynam. 35:882-887, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Meredith J McGee
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, North Carolina. .,Department of Neurobiology, Duke University, Durham, North Carolina. .,Department of Surgery, Duke University, Durham, North Carolina. .,Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina.
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Danziger ZC, Grill WM. Sensory and circuit mechanisms mediating lower urinary tract reflexes. Auton Neurosci 2015; 200:21-28. [PMID: 26119358 DOI: 10.1016/j.autneu.2015.06.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 03/27/2015] [Accepted: 06/02/2015] [Indexed: 02/08/2023]
Abstract
Neural control of continence and micturition is distributed over a network of interconnected reflexes. These reflexes integrate sensory information from the bladder and urethra and are modulated by descending influences to produce different physiological outcomes based on the information arriving from peripheral afferents. Therefore, the mode of activation of primary afferents is essential in understanding the action of spinal reflex pathways in the lower urinary tract. We present an overview of sensory mechanisms in the bladder and urethra focusing on their spinal integration, identify the cardinal spinal reflexes responsible for continence and micturition, and describe how their functional role is controlled via peripheral afferent activity.
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Affiliation(s)
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, NC, USA; Department of Neurobiology, Duke University, Durham, NC, USA; Department of Surgery, Duke University, Durham, NC, USA; Department of Electrical and Computer Engineering, Duke University, Durham, NC, USA
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Galluzzi F, De Rensis F, Saleri R, Spattini G. Effect of urethral infusion of atracurium besylate on manual bladder expression in dogs and cats with spinal cord injuries: a randomised trial. Vet Rec 2015; 176:545. [DOI: 10.1136/vr.102825] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/07/2015] [Indexed: 11/04/2022]
Affiliation(s)
- F. Galluzzi
- Veterinary Clinic Castellarano; Castellarano (RE) Italy
| | - F. De Rensis
- Department of Veterinary Medicine; University of Parma; Parma Italy
| | - R. Saleri
- Department of Veterinary Medicine; University of Parma; Parma Italy
| | - G. Spattini
- Veterinary Clinic Castellarano; Castellarano (RE) Italy
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Affiliation(s)
- Craig V Comiter
- Departments of Urology, and Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California
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Kossler AL, Wang J, Feuer W, Tse DT. Neurostimulation of the lacrimal nerve for enhanced tear production. Ophthalmic Plast Reconstr Surg 2015; 31:145-51. [PMID: 25126767 PMCID: PMC4329098 DOI: 10.1097/iop.0000000000000234] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE To design a proof-of-concept study to assess the effect of lacrimal nerve stimulation (LNS) with an implantable pulse generator (IPG) to increase aqueous tear production. METHODS Experimental animal study design of 6 Dutch Belted rabbits. Ultra high-resolution optical coherence tomography (UHR-OCT) quantified tear production by measuring the baseline tear volume of each rabbit's OD and OS. A neurostimulator was implanted adjacent to the right lacrimal nerve. After 2 minutes of LNS (100 μs, 1.6 mA, 20 Hz, 5-8 V), the tear volumes were measured with UHR-OCT. The change in tear volume was quantified and compared with the nonstimulated OS. Three rabbits underwent chronic LNS (100 μs, 1.6 mA, 10 Hz, 2 V) and their lacrimal glands were harvested for histopathologic analysis. RESULTS The UHR-OCT imaging of the OD tear volume showed a 441% average increase in tear production after LNS as a percent of baseline. After stimulation, OD had statistically significant greater increase in tear volumes than OS (p = 0.028, Wilcoxon test). Poststimulation OD tear volumes were significantly greater compared with baseline (p = 0.028, Wilcoxon test). Histopathologic examination of the lacrimal glands showed no discernible tissue damage from chronic neurostimulation. In addition, there were no gross adverse effects on the general well-being of the animals due to chronic stimulation. CONCLUSIONS LNS with an IPG appears to increase aqueous tear production. Chronic LNS showed no histopathologic lacrimal gland damage. This study suggests that LNS is a promising new treatment strategy to increase aqueous tear production.
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Affiliation(s)
| | - Jianhua Wang
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine
| | - William Feuer
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine
| | - David T. Tse
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine
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McGee MJ, Amundsen CL, Grill WM. Electrical stimulation for the treatment of lower urinary tract dysfunction after spinal cord injury. J Spinal Cord Med 2015; 38:135-46. [PMID: 25582564 PMCID: PMC4397195 DOI: 10.1179/2045772314y.0000000299] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Electrical stimulation for bladder control is an alternative to traditional methods of treating neurogenic lower urinary tract dysfunction (NLUTD) resulting from spinal cord injury (SCI). In this review, we systematically discuss the neurophysiology of bladder dysfunction following SCI and the applications of electrical stimulation for bladder control following SCI, spanning from historic clinical approaches to recent pre-clinical studies that offer promising new strategies that may improve the feasibility and success of electrical stimulation therapy in patients with SCI. Electrical stimulation provides a unique opportunity to control bladder function by exploiting neural control mechanisms. Our understanding of the applications and limitations of electrical stimulation for bladder control has improved due to many pre-clinical studies performed in animals and translational clinical studies. Techniques that have emerged as possible opportunities to control bladder function include pudendal nerve stimulation and novel methods of stimulation, such as high frequency nerve block. Further development of novel applications of electrical stimulation will drive progress towards effective therapy for SCI. The optimal solution for restoration of bladder control may encompass a combination of efficient, targeted electrical stimulation, possibly at multiple locations, and pharmacological treatment to enhance symptom control.
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Affiliation(s)
- Meredith J. McGee
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | | | - Warren M. Grill
- Correspondence to: Warren M. Grill, Department of Biomedical Engineering, Duke University, 136 Hudson Hall, Box 90281, Durham, NC 27708-0281 USA.
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Kovacevic M, Yoo PB. Reflex neuromodulation of bladder function elicited by posterior tibial nerve stimulation in anesthetized rats. Am J Physiol Renal Physiol 2015; 308:F320-9. [DOI: 10.1152/ajprenal.00212.2014] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although posterior tibial nerve stimulation (PTNS) has been shown in both clinical and animal studies to elicit bladder-inhibitory reflexes, our understanding of the role of posterior tibial nerve (PTN) afferents that elicit these responses is significantly limited. To this end, we investigated the effects of frequency-dependant PTNS in urethane-anesthetized rats undergoing repeated urodynamic fills. Nerve stimulation trials (10 min) resulted in statistically significant inhibition of the urinary bladder, both during and after nerve stimulation ( P < 0.05). PTNS applied at 5 Hz resulted in both acute and prolonged changes that corresponded to 38.0% and 34.1% reductions in the bladder contraction frequency, respectively. In contrast, PTNS applied at 10 Hz could only elicit an acute decrease (22.9%) in bladder activity. Subsequent electrical activation of individual PTN branches (lateral or medial plantar nerves) confirmed that these bladder reflexes are mediated by specific subsets of the PTN trunk. Both acute and prolonged inhibition of the bladder were achieved by electrical stimulation of the lateral plantar (10 and 20 Hz) and medial plantar (5 and 10 Hz) nerves. Finally, we report a bladder-excitatory reflex that is elicited by electrical activation of either the PTN trunk or lateral plantar nerve at 50 Hz. This study shows that multiple bladder reflexes are tuned to specific subsets of nerve afferents and stimulation frequencies, each of which provide novel insights into the physiological effects of PTNS.
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Affiliation(s)
- Mario Kovacevic
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada; and
| | - Paul B. Yoo
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada; and
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario, Canada
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de Groat WC, Tai C. Impact of Bioelectronic Medicine on the Neural Regulation of Pelvic Visceral Function. Bioelectron Med 2015; 2015:25-36. [PMID: 26491706 PMCID: PMC4610375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023] Open
Abstract
Neuromodulation elicited by electrical stimulation of peripheral or spinal nerves is a U.S. Food and Drug Administered (FDA)-approved therapy for treating disorders of the pelvic viscera, including urinary urgency, urgency-frequency, nonobstructive urinary retention and fecal incontinence. The technique is also being tested experimentally for its efficacy in treating interstitial cystitis, chronic constipation and pelvic pain. The goal of neuromodulation is to suppress abnormal visceral sensations and involuntary reflexes and restore voluntary control. Although detailed mechanisms underlying the effects of neuromodulation are still to be elucidated, it is generally believed that effects are due to stimulation of action potentials in somatic afferent nerves. Afferent nerves project to the lumbosacral spinal cord, where they release excitatory neurotransmitters that activate ascending pathways to the brain or spinal circuits that modulate visceral sensory and involuntary motor mechanisms. Studies in animals revealed that different types of neuromodulation (for example, stimulation of a sacral spinal root, pudendal nerve or posterior tibial nerve) act by releasing different inhibitory and excitatory neurotransmitters in the central nervous system. In addition, certain types of neuromodulation inhibit visceral smooth muscle by initiating reflex firing in peripheral autonomic nerves or excite striated sphincter muscles by initiating reflex firing in somatic efferent nerves. This report will provide a brief summary of (a) neural control of the lower urinary tract and distal bowel, (b) clinical use of neuromodulation in the treatment of bladder and bowel dysfunctions,
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Affiliation(s)
- William C de Groat
- Department of Pharmacology and Chemical Biology, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
| | - Changfeng Tai
- Department of Pharmacology and Chemical Biology, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
- Department of Urology, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
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de Groat WC, Tai C. Impact of Bioelectronic Medicine on the Neural Regulation of Pelvic Visceral Function. Bioelectron Med 2015. [DOI: 10.15424/bioelectronmed.2015.00003] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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Wark HAC, Black SR, Mathews KS, Cartwright PC, Gustafson KJ, Normann RA. Restoration from acute urinary dysfunction using Utah electrode arrays implanted into the feline pudendal nerve. Neuromodulation 2014; 18:317-23. [PMID: 25430001 DOI: 10.1111/ner.12259] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 09/22/2014] [Indexed: 11/27/2022]
Abstract
OBJECTIVES To investigate intrafascicular pudendal nerve stimulation in felines as a means to restore urinary function in acute models of urinary incontinence, overactive bladder, and underactive bladder. MATERIALS AND METHODS Felines were anesthetized, and high-electrode-count (48 electrodes; 25 electrodes/mm(2) ) electrode arrays were implanted intrafascicularly into the pudendal nerve trunk. Electrodes were mapped for their ability to selectively or nonselectively excite the external anal sphincter, external urethral sphincter, and the detrusor bladder muscle. Statistical analysis was carried out to quantify reflexive voiding efficiencies, mean impedances of the microelectrodes used in this study, and to determine what differences, if any, in bladder contraction amplitudes were evoked by different electrode configurations. RESULTS Multielectrode arrays implanted into the pudendal nerve trunk were able to selectively and nonselectively excite genitourinary muscles. After inducing urinary incontinence with bilateral pudendal nerve transections (proximal to the implants), electrical stimulation delivered through certain microelectrodes was able to significantly reduce leaking (p = 0.008). Electrical stimulation delivered through detrusor selective electrodes was able to inhibit reflexive bladder contractions and excite bladder contractions, depending on the stimulation frequency. Specific electrode configurations were able to drive significantly (p < 0.001) larger bladder contractions than other electrode configurations, depending on the preparation. Successful reflexively or electrically driven bladder contractions were achieved in 46% and 38% of the preparations, respectively, an observation that has not been noted in previously published feline pudendal stimulation studies. CONCLUSIONS Multielectrode arrays implanted intrafascicularly into the pudendal nerve trunk may provide a promising new clinical neuromodulation therapy for the restoration of urinary function.
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Affiliation(s)
| | - Shana R Black
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA
| | | | - Patrick C Cartwright
- Department of Urology and Urological Surgery, University of Utah, Salt Lake City, UT, USA
| | - Kenneth J Gustafson
- Department of Bioengineering, Case Western Reserve University, Cleveland, OH, USA
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McGee MJ, Danziger ZC, Bamford JA, Grill WM. A spinal GABAergic mechanism is necessary for bladder inhibition by pudendal afferent stimulation. Am J Physiol Renal Physiol 2014; 307:F921-30. [PMID: 25143456 DOI: 10.1152/ajprenal.00330.2014] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Electrical stimulation of pudendal afferents can inhibit bladder contractions and increase bladder capacity. Recent results suggest that stimulation-evoked bladder inhibition is mediated by a mechanism other than activation of sympathetic bladder efferents in the hypogastric nerve, generating α-adrenergic receptor-mediated inhibition at the vesical ganglia and/or β-adrenergic receptor-mediated direct inhibition of the detrusor muscle. We investigated several inhibitory neurotransmitters that may instead be necessary for stimulation-evoked inhibition and found that intravenous picrotoxin, a noncompetitive GABAA antagonist, significantly and reversibly blocked pudendal afferent stimulation-evoked inhibition of bladder contractions in a dose-dependent manner. Similarly, intravenous picrotoxin also blocked pudendal afferent stimulation-evoked inhibition of nociceptive bladder contractions evoked by acetic acid infusion. Furthermore, intrathecal administration of picrotoxin at the lumbosacral spinal cord also blocked bladder inhibition by pudendal afferent stimulation. On the other hand, glycinergic, adrenergic, or opioidergic mechanisms were not necessary for bladder inhibition evoked by pudendal afferent stimulation. These results identify a lumbosacral spinal GABAergic mechanism of bladder inhibition evoked by pudendal afferent stimulation.
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Affiliation(s)
- Meredith J McGee
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Zachary C Danziger
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Jeremy A Bamford
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, North Carolina; Department of Neurobiology, Duke University, Durham, North Carolina; Department of Surgery, Duke University, Durham, North Carolina; and Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina
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Bruns TM, Weber DJ, Gaunt RA. Microstimulation of afferents in the sacral dorsal root ganglia can evoke reflex bladder activity. Neurourol Urodyn 2014; 34:65-71. [PMID: 24464833 DOI: 10.1002/nau.22514] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Accepted: 09/19/2013] [Indexed: 11/07/2022]
Abstract
AIMS Pudendal afferent fibers can be excited using electrical stimulation to evoke reflex bladder activity. While this approach shows promise for restoring bladder function, stimulation of desired pathways, and integration of afferent signals for sensory feedback remains challenging. At sacral dorsal root ganglia (DRG), the convergence of pelvic and pudendal afferent fibers provides a unique location for access to lower urinary tract neurons. Our goal in this study was to demonstrate the potential of microstimulation in sacral DRG for evoking reflex bladder responses. METHODS Penetrating microelectrode arrays were inserted in the left S1 and S2 DRG of six anesthetized adult male cats. While the bladder volume was held at a level below the leak volume, single and multiple channel stimulation was performed using various stimulation patterns. RESULTS Reflex bladder excitation was observed in five cats, for stimulation in either S1 or S2 DRG at 1 Hz and 30-33 Hz with a pulse amplitude of 10-50 µA. Bladder relaxation was observed during a few trials. Adjacent electrodes frequently elicited very different responses. CONCLUSIONS These results demonstrate the potential of low-current microstimulation to recruit reflexive bladder responses. An approach such as this could be integrated with DRG recordings of bladder afferents to provide a closed-loop bladder neuroprosthesis.
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Affiliation(s)
- Tim M Bruns
- Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, Pennysylvania
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Yang G, Wang J, Shen B, Roppolo JR, de Groat WC, Tai C. Pudendal nerve stimulation and block by a wireless-controlled implantable stimulator in cats. Neuromodulation 2013; 17:490-6; discussion 496. [PMID: 24320615 DOI: 10.1111/ner.12136] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 09/20/2013] [Accepted: 10/25/2013] [Indexed: 11/27/2022]
Abstract
OBJECTIVE The study aims to determine the functionality of a wireless-controlled implantable stimulator designed for stimulation and block of the pudendal nerve. MATERIALS AND METHODS In five cats under α-chloralose anesthesia, the stimulator was implanted underneath the skin on the left side in the lower back along the sacral spine. Two tripolar cuff electrodes were implanted bilaterally on the pudendal nerves in addition to one bipolar cuff electrode that was implanted on the left side central to the tripolar cuff electrode. The stimulator provided high-frequency (5-20 kHz) biphasic stimulation waveforms to the two tripolar electrodes and low-frequency (1-100 Hz) rectangular pulses to the bipolar electrode. Bladder and urethral pressures were measured to determine the effects of pudendal nerve stimulation (PNS) or block. RESULTS The maximal (70-100 cmH2O) urethral pressure generated by 20-Hz PNS applied via the bipolar electrode was completely eliminated by the pudendal nerve block induced by the high-frequency stimulation (6-15 kHz, 6-10 V) applied via the two tripolar electrodes. In a partially filled bladder, 20-30 Hz PNS (2-8 V, 0.2 ms) but not 5 Hz stimulation applied via the bipolar electrode elicited a large sustained bladder contraction (45.9 ± 13.4 to 52.0 ± 22 cmH2O). During cystometry, the 5 Hz PNS significantly (p < 0.05) increased bladder capacity to 176.5 ± 27.1% of control capacity. CONCLUSIONS The wireless-controlled implantable stimulator successfully generated the required waveforms for stimulation and block of pudendal nerve, which will be useful for restoring bladder functions after spinal cord injury.
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Affiliation(s)
- Guangning Yang
- Department of Urology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Biomedical Engineering, Beijing Jiaotong University, China
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Adami C, Dayer T, Spadavecchia C, Angeli G. Ultrasound-guided pudendal nerve block in cats undergoing perineal urethrostomy: a prospective, randomised, investigator-blind, placebo-controlled clinical trial. J Feline Med Surg 2013; 16:340-5. [PMID: 24174501 DOI: 10.1177/1098612x13509082] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The objective of this study was to evaluate the clinical usefulness, in terms of analgesic efficacy and safety, of ultrasound-guided pudendal nerve block performed with bupivacaine in cats undergoing perineal urethrostomy. Eighteen client-owned male cats scheduled for perineal urethrostomy were enrolled in the study and assigned to one of two treatment groups. The pudendal nerve block was performed under general anaesthesia, as described elsewhere, with 0.3 ml/kg of either saline (group C) or 0.5% bupivacaine (group B) - the total injection volume being split equally between the two sites of injection (left and right). Intra-operatively, assessment of nociception was based on the rescue analgesics requirement, as well as on the evaluation of changes in physiological parameters in comparison with the baseline values. Postoperative pain assessment was performed using three different pain scales at recovery and then 1, 2 and 3 h after recovery. Cats in group B showed lower heart rates and required fewer analgesics during surgery than group C. Postoperatively, group B had lower pain scores and needed less rescue buprenorphine than group C. Iatrogenic block-related complications were not observed. In conclusion, the ultrasound-guided pudendal nerve block can be considered clinically useful in feline medicine as it provides reliable analgesia in cats undergoing perineal urethrostomy.
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Affiliation(s)
- Chiara Adami
- 1Department of Veterinary Clinical Science, Anaesthesiology and Pain Therapy Division, Vetsuisse Faculty, University of Berne, Berne, Switzerland
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Kullmann FA, Wells GI, Langdale CL, Zheng J, Thor KB. Stability of the acetic acid-induced bladder irritation model in alpha chloralose-anesthetized female cats. PLoS One 2013; 8:e73771. [PMID: 24040064 PMCID: PMC3767621 DOI: 10.1371/journal.pone.0073771] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 07/24/2013] [Indexed: 01/23/2023] Open
Abstract
Time- and vehicle-related variability of bladder and urethral rhabdosphincter (URS) activity as well as cardiorespiratory and blood chemistry values were examined in the acetic acid-induced bladder irritation model in α-chloralose-anesthetized female cats. Additionally, bladder and urethra were evaluated histologically using Mason trichrome and toluidine blue staining. Urodynamic, cardiovascular and respiratory parameters were collected during intravesical saline infusion followed by acetic acid (0.5%) to irritate the bladder. One hour after starting acetic acid infusion, a protocol consisting of a cystometrogram, continuous infusion-induced rhythmic voiding contractions, and a 5 min "quiet period" (bladder emptied without infusion) was precisely repeated every 30 minutes. Administration of vehicle (saline i.v.) occurred 15 minutes after starting each of the first 7 cystometrograms and duloxetine (1mg/kg i.v.) after the 8(th). Acetic acid infusion into the bladder increased URS-EMG activity, bladder contraction frequency, and decreased contraction amplitude and capacity, compared to saline. Bladder activity and URS activity stabilized within 1 and 2 hours, respectively. Duloxetine administration significantly decreased bladder contraction frequency and increased URS-EMG activity to levels similar to previous reports. Cardiorespiratory parameters and blood gas levels remained consistent throughout the experiment. The epithelium of the bladder and urethra were greatly damaged and edema and infiltration of neutrophils in the lamina propria of urethra were observed. These data provide an ample evaluation of the health of the animals, stability of voiding function and appropriateness of the model for testing drugs designed to evaluate lower urinary tract as well as cardiovascular and respiratory systems function.
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Affiliation(s)
- F. Aura Kullmann
- Urogenix Inc./Astellas, Durham, North Carolina, United States of America
| | - Grace I. Wells
- Urogenix Inc./Astellas, Durham, North Carolina, United States of America
| | | | - Jihong Zheng
- Urogenix Inc./Astellas, Durham, North Carolina, United States of America
| | - Karl B. Thor
- Urogenix Inc./Astellas, Durham, North Carolina, United States of America
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McGee MJ, Grill WM. Selective co-stimulation of pudendal afferents enhances bladder activation and improves voiding efficiency. Neurourol Urodyn 2013; 33:1272-8. [PMID: 23934615 DOI: 10.1002/nau.22474] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 07/08/2013] [Indexed: 11/07/2022]
Abstract
AIMS Clinical application of pudendal nerve (PN) afferent stimulation to restore bladder emptying in persons with neurological disorders requires increased stimulation-evoked voiding efficiencies (VEs). We tested the hypothesis that selective co-stimulation of multiple PN branches, either bilateral dorsal nerve of the penis (DNP) stimulation or selective stimulation of both the cranial sensory nerve (CSN) and DNP, will evoke larger reflex bladder contractions and result in higher VEs than stimulation of any single afferent pathway alone. METHODS We measured the strength of bladder contractions, threshold volumes, and VEs produced by unilateral and bilateral stimulation of the DNP as well as singular and selective unilateral co-stimulation of the DNP and CSN in cats anesthetized with α-chloralose. RESULTS Co-stimulation of afferent pathways generated significantly larger isovolumetric bladder contractions and evoked contractions at lower threshold volumes than individual stimulation. Co-stimulation of pudendal afferents also suppressed dyssynergic activity in the external anal sphincter produced by low frequency individual stimulation. VE was significantly improved with co-stimulation (172 ± 6% of distention evoked volumes) over individual stimulation (141 ± 6%). CONCLUSIONS Both types of co-stimulation evoked larger bladder contractions and increased VE over individual branch PN afferent stimulation and distention-evoked voiding. The decreased threshold volumes required for reflex bladder activation and increased VEs with co-stimulation support the use of stimulation of multiple individual stimulation-evoked reflexes to improve voiding efficiency.
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Affiliation(s)
- Meredith J McGee
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
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Adami C, Angeli G, Haenssgen K, Stoffel MH, Spadavecchia C. Development of an ultrasound-guided technique for pudendal nerve block in cat cadavers. J Feline Med Surg 2013; 15:901-7. [PMID: 23599255 DOI: 10.1177/1098612x13485482] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The objective of this prospective experimental cadaveric study was to develop an ultrasound-guided technique to perform an anaesthetic pudendal nerve block in male cats. Fifteen fresh cadavers were used for this trial. A detailed anatomical dissection was performed on one cat in order to scrutinise the pudendal nerve and its ramifications. In a second step, the cadavers of six cats were used to test three different ultrasonographic approaches to the pudendal nerve: the deep dorso-lateral, the superficial dorso-lateral and the median transperineal. Although none of the approaches allowed direct ultrasonographical identification of the pudendal nerve branches, the deep dorso-lateral was found to be the most advantageous one in terms of practicability and ability to identify useful and reliable landmarks. Based on these findings, the deep dorso-lateral approach was selected as technique of choice for tracer injections (0.1 ml 1% methylene blue injected bilaterally) in six cat cadavers distinct from those used for the ultrasonographical study. Anatomical dissection revealed a homogeneous spread of the tracer around the pudendal nerve sensory branches in all six cadavers. Finally, computed tomography was performed in two additional cadavers after injection of 0.3 ml/kg (0.15 ml/kg per each injection sites, left and right) contrast medium through the deep dorso-lateral approach in order to obtain a model of volume distribution applicable to local anaesthetics. Our findings in cat cadavers indicate that ultrasound-guided pudendal nerve block is feasible and could be proposed to provide peri-operative analgesia in clinical patients undergoing perineal urethrostomy.
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Affiliation(s)
- Chiara Adami
- 1Department of Veterinary Clinical Science, Anesthesiology and Pain Therapy Division, Vetsuisse Faculty, University of Berne, Berne, Switzerland
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Kent AR, Grill WM. Model-based analysis and design of nerve cuff electrodes for restoring bladder function by selective stimulation of the pudendal nerve. J Neural Eng 2013; 10:036010. [PMID: 23594706 DOI: 10.1088/1741-2560/10/3/036010] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Electrical stimulation of the pudendal nerve (PN) is being developed as a means to restore bladder function in persons with spinal cord injury. A single nerve cuff electrode placed on the proximal PN trunk may enable selective stimulation of distinct fascicles to maintain continence or evoke micturition. The objective of this study was to design a nerve cuff that enabled selective stimulation of the PN. APPROACH We evaluated the performance of both flat interface nerve electrode (FINE) cuff and round cuff designs, with a range of FINE cuff heights and number of contacts, as well as multiple contact orientations. This analysis was performed using a computational model, in which the nerve and fascicle cross-sectional positions from five human PN trunks were systematically reshaped within the nerve cuff. These cross-sections were used to create finite element models, with electric potentials calculated and applied to a cable model of a myelinated axon to evaluate stimulation selectivity for different PN targets. Subsequently, the model was coupled to a genetic algorithm (GA) to identify solutions that used multiple contact activation to maximize selectivity and minimize total stimulation voltage. MAIN RESULTS Simulations did not identify any significant differences in selectivity between FINE and round cuffs, although the latter required smaller stimulation voltages for target activation due to preserved localization of targeted fascicle groups. Further, it was found that a ten contact nerve cuff generated sufficient selectivity for all PN targets, with the degree of selectivity dependent on the relative position of the target within the nerve. The GA identified solutions that increased fitness by 0.7-45.5% over single contact activation by decreasing stimulation of non-targeted fascicles. SIGNIFICANCE This study suggests that using an optimal nerve cuff design and multiple contact activation could enable selective stimulation of the human PN trunk for restoration of bladder function.
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Affiliation(s)
- Alexander R Kent
- Department of Biomedical Engineering, Duke University, Durham, NC 27710, USA
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Yoo PB, Lubock NB, Hincapie JG, Ruble SB, Hamann JJ, Grill WM. High-resolution measurement of electrically-evoked vagus nerve activity in the anesthetized dog. J Neural Eng 2013; 10:026003. [PMID: 23370017 DOI: 10.1088/1741-2560/10/2/026003] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Not fully understanding the type of axons activated during vagus nerve stimulation (VNS) is one of several factors that limit the clinical efficacy of VNS therapies. The main goal of this study was to characterize the electrical recruitment of both myelinated and unmyelinated fibers within the cervical vagus nerve. APPROACH In anesthetized dogs, recording nerve cuff electrodes were implanted on the vagus nerve following surgical excision of the epineurium. Both the vagal electroneurogram (ENG) and laryngeal muscle activity were recorded in response to stimulation of the right vagus nerve. MAIN RESULTS Desheathing the nerve significantly increased the signal-to-noise ratio of the ENG by 1.2 to 9.9 dB, depending on the nerve fiber type. Repeated VNS following nerve transection or neuromuscular block (1) enabled the characterization of A-fibers, two sub-types of B-fibers, and unmyelinated C-fibers, (2) confirmed the absence of stimulation-evoked reflex compound nerve action potentials in both the ipsilateral and contralateral vagus nerves, and (3) provided evidence of stimulus spillover into muscle tissue surrounding the stimulating electrode. SIGNIFICANCE Given the anatomical similarities between the canine and human vagus nerves, the results of this study provide a template for better understanding the nerve fiber recruitment patterns associated with VNS therapies.
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Affiliation(s)
- Paul B Yoo
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada.
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McGee MJ, Yoo PB, Grill WM. Selective co-stimulation of pudendal afferents enhances reflex bladder activation. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2012; 2011:1057-60. [PMID: 22254495 DOI: 10.1109/iembs.2011.6090246] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The loss of normal bladder function is common in persons with spinal cord injury (SCI) and negatively impacts their quality of life. Electrical stimulation of pudendal nerve afferents is a promising approach to restore control of bladder function. Pudendal afferent stimulation can generate reflex contraction of the bladder, but the resulting bladder voiding efficiency remains low. The objective of this work was t o evaluate selective co-stimulation of two branches of the pudendal nerve--the cranial urethral sensory nerve (CSN) and the dorsal nerve of the penis (DNP)--as a means to enhance reflex bladder activation and bladder voiding efficiency. In preclinical studies in anesthetized adult cats, co-stimulation of CSN and DNP evoked larger bladder contractions than individual stimulation of either CSN or DNP. In a parallel clinical experiment involving a participant with chronic SCI, co-stimulation of the proximal and distal urethra also produced synergistic augmentation of reflex bladder activity, and thus improved voiding efficiency when compared to reflex distension-evoked voiding. Selective co-stimulation of pudendal afferents is efficacious and should be considered in the development of neural prosthetics for restoration of bladder function in persons with SCI.
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Affiliation(s)
- Meredith J McGee
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA.
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