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Strohman A, Isaac G, Payne B, Verdonk C, Khalsa SS, Legon W. Low-intensity focused ultrasound to the human insular cortex differentially modulates the heartbeat-evoked potential: a proof-of-concept study. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.08.584152. [PMID: 38559271 PMCID: PMC10979877 DOI: 10.1101/2024.03.08.584152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Background The heartbeat evoked potential (HEP) is a brain response time-locked to the heartbeat and a potential marker of interoceptive processing. The insula and dorsal anterior cingulate cortex (dACC) are brain regions that may be involved in generating the HEP. Low-intensity focused ultrasound (LIFU) is a non-invasive neuromodulation technique that can selectively target sub-regions of the insula and dACC to better understand their contributions to the HEP. Objective Proof-of-concept study to determine whether LIFU modulation of the anterior insula (AI), posterior insula (PI), and dACC influences the HEP. Methods In a within-subject, repeated-measures design, healthy human participants (n=16) received 10 minutes of stereotaxically targeted LIFU to the AI, PI, dACC or Sham at rest during continuous electroencephalography (EEG) and electrocardiography (ECG) recording on separate days. Primary outcome was change in HEP amplitudes. Relationships between LIFU pressure and HEP changes were examined using linear mixed modelling. Peripheral indices of visceromotor output including heart rate and heart rate variability (HRV) were explored between conditions. Results Relative to sham, LIFU to the PI, but not AI or dACC, decreased HEP amplitudes; this was partially explained by increased LIFU pressure. LIFU did not affect time or frequency dependent measures of HRV. Conclusions These results demonstrate the ability to modulate HEP amplitudes via non-invasive targeting of key interoceptive brain regions. Our findings have implications for the causal role of these areas in bottom-up heart-brain communication that could guide future work investigating the HEP as a marker of interoceptive processing in healthy and clinical populations.
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Affiliation(s)
- Andrew Strohman
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, 24016, USA
- Virginia Tech Carilion School of Medicine, Roanoke, VA, 24016, USA
- Graduate Program in Translational Biology, Medicine, and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, 24016, USA
| | - Gabriel Isaac
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, 24016, USA
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, 24016, USA
| | - Brighton Payne
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, 24016, USA
| | - Charles Verdonk
- Laureate Institute for Brain Research, Tulsa, OK, USA
- VIFASOM (EA 7330 Vigilance Fatigue, Sommeil et Santé Publique), Université Paris Cité, Paris, France
- French Armed Forces Biomedical Research Institute, Brétigny-sur-Orge, France
| | - Sahib S. Khalsa
- Laureate Institute for Brain Research, Tulsa, OK, USA
- Oxley College of Health Sciences, University of Tulsa, Tulsa, OK, USA
| | - Wynn Legon
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, 24016, USA
- Center for Human Neuroscience Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, 24016, USA
- Center for Health Behaviors Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, 24016, USA
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, 24016, USA
- Virginia Tech Carilion School of Medicine, Roanoke, VA, 24016, USA
- Graduate Program in Translational Biology, Medicine, and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, 24016, USA
- Department of Neurosurgery, Carilion Clinic, Roanoke, VA, 24016, USA
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Yan Y, Tennekoon K, Eubanks A, Herekar A, Shimoga D, Ayyala D, McLeod C, Kurek JA, Morgan JC, Rao SSC, Sharma A. Evaluation of bidirectional gut-brain axis and anorectal function in Parkinson's disease with constipation. Neurogastroenterol Motil 2024; 36:e14728. [PMID: 38105462 DOI: 10.1111/nmo.14728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 11/08/2023] [Accepted: 12/06/2023] [Indexed: 12/19/2023]
Abstract
BACKGROUND Parkinson's disease (PD) is a neurodegenerative movement disorder with prodromal and highly prevalent gastrointestinal (GI) symptoms, especially constipation. Although PD models suggest gut-brain axis dysfunction, the mechanistic underpinnings and their correlation with GI symptoms are poorly understood. AIM To examine the bidirectional gut-brain axis function in PD and correlate it with constipation severity, PD duration, and severity. METHODS Rectal sensory thresholds and afferent cortical evoked potentials (CEP) were assessed using a 4-ring EMG electrode probe. Efferent anal and rectal motor evoked potentials (MEPs) were obtained following transcranial and lumbosacral magnetic stimulation. Bowel symptoms were assessed by prospective stool diary. The CEP and MEP latencies, rectal sensory thresholds, and anorectal sensorimotor data were compared between PD subjects and age-adjusted healthy subjects. KEY RESULTS Twenty-five PD subjects with constipation (F/M = 6/19) and 20 healthy subjects (F/M = 14/6) were enrolled. The first and pain sensation thresholds were higher in PD subjects than healthy subjects (p < 0.002) but lost significance after adjustment for age. Age-adjusted rectal CEP and right-sided cortico-anal MEP latencies were prolonged in PD subjects compared to healthy subjects (p < 0.04). Also, half (4 of 8) age-adjusted spino-anal and rectal MEP latencies in PD subjects were significantly longer. In multivariate linear analysis, first rectal sensation and right-sided MEP latencies showed moderate correlation with constipation severity. CONCLUSIONS & INFERENCES Parkinson's disease is associated with significant bidirectional gut-brain axis dysfunction as evidenced by prolonged afferent and efferent neuronal signaling. Constipation severity in PD is correlated to abnormal rectal sensation and lateralized disturbance of efferent brain-gut signaling.
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Affiliation(s)
- Yun Yan
- Digestive Clinical Research Center, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Karunaratne Tennekoon
- Digestive Clinical Research Center, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Audrey Eubanks
- Digestive Clinical Research Center, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Anam Herekar
- Digestive Clinical Research Center, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Dhanush Shimoga
- Digestive Clinical Research Center, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Deepak Ayyala
- Department of Population Health Sciences, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Colin McLeod
- Department of Neurology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Julie A Kurek
- Department of Neurology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - John C Morgan
- Department of Neurology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Satish S C Rao
- Digestive Clinical Research Center, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Amol Sharma
- Digestive Clinical Research Center, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
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Mayeli A, Al Zoubi O, White EJ, Chappelle S, Kuplicki R, Morton A, Bruce J, Smith R, Feinstein JS, Bodurka J, Paulus MP, Khalsa SS. Parieto-occipital ERP indicators of gut mechanosensation in humans. Nat Commun 2023; 14:3398. [PMID: 37311748 PMCID: PMC10264354 DOI: 10.1038/s41467-023-39058-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 05/24/2023] [Indexed: 06/15/2023] Open
Abstract
Understanding the neural processes governing the human gut-brain connection has been challenging due to the inaccessibility of the body's interior. Here, we investigated neural responses to gastrointestinal sensation using a minimally invasive mechanosensory probe by quantifying brain, stomach, and perceptual responses following the ingestion of a vibrating capsule. Participants successfully perceived capsule stimulation under two vibration conditions (normal and enhanced), as evidenced by above chance accuracy scores. Perceptual accuracy improved significantly during the enhanced relative to normal stimulation, which was associated with faster stimulation detection and reduced reaction time variability. Capsule stimulation induced late neural responses in parieto-occipital electrodes near the midline. Moreover, these 'gastric evoked potentials' showed intensity-dependent increases in amplitude and were significantly correlated with perceptual accuracy. Our results replicated in a separate experiment, and abdominal X-ray imaging localized most capsule stimulations to the gastroduodenal segments. Combined with our prior observation that a Bayesian model is capable of estimating computational parameters of gut-brain mechanosensation, these findings highlight a unique form of enterically-focused sensory monitoring within the human brain, with implications for understanding gut feelings and gut-brain interactions in healthy and clinical populations.
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Affiliation(s)
- Ahmad Mayeli
- Laureate Institute for Brain Research, Tulsa, OK, USA
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Obada Al Zoubi
- Laureate Institute for Brain Research, Tulsa, OK, USA
- Harvard Medical School/McLean Hospital, Boston, MA, USA
| | - Evan J White
- Laureate Institute for Brain Research, Tulsa, OK, USA
| | | | | | - Alexa Morton
- Laureate Institute for Brain Research, Tulsa, OK, USA
| | - Jaimee Bruce
- Laureate Institute for Brain Research, Tulsa, OK, USA
| | - Ryan Smith
- Laureate Institute for Brain Research, Tulsa, OK, USA
| | | | - Jerzy Bodurka
- Laureate Institute for Brain Research, Tulsa, OK, USA
- Stephenson School of Biomedical Engineering, University of Oklahoma, Tulsa, OK, USA
| | - Martin P Paulus
- Laureate Institute for Brain Research, Tulsa, OK, USA
- Oxley College of Health Sciences, University of Tulsa, Tulsa, OK, USA
| | - Sahib S Khalsa
- Laureate Institute for Brain Research, Tulsa, OK, USA.
- Oxley College of Health Sciences, University of Tulsa, Tulsa, OK, USA.
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Yan Y, Shimoga D, Sharma A. Parkinson's Disease and Diabetes Mellitus: Synergistic Effects on Pathophysiology and GI Motility. Curr Gastroenterol Rep 2023; 25:106-113. [PMID: 37067721 DOI: 10.1007/s11894-023-00868-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/14/2023] [Indexed: 04/18/2023]
Abstract
PURPOSE OF REVIEW Parkinson's disease and diabetes affect an increasing proportion of the aging global population. Both conditions extensively affect gastrointestinal (GI) motility with similar and differing clinical symptoms. Nonetheless, GI symptoms in Parkinson's disease and diabetes pose significant morbidity and impairment of quality of life. Their pathophysiology is poorly understood, and therefore, effective treatment options are lacking. RECENT FINDINGS Parkinson's disease patients have oropharyngeal dysphagia and constipation. They also have mild or absent upper GI symptoms associated with delayed gastric emptying, which is prevalent in 70% of patients. Delayed gastric emptying in Parkinson's disease leads to erratic medication absorption and fluctuating motor symptoms. Half of diabetics have upper GI symptoms, which correlate to gastric emptying and changes in brain activity of the insular cortex. The majority of diabetics also have constipation. Diabetics have an increased risk for developing Parkinson's disease and anti-diabetic medications are associated with risk reduction of developing Parkinson's disease. Hyperglycemia is associated with advanced glycated end products formation and acceleration of α-synuclein aggregation. GLP-1 receptor agonists have also demonstrated efficacy in improving motor symptoms and cognition in Parkinson's disease patients with diabetes. Parkinson's disease and diabetes are pan-enteric disorders with significant GI symptoms and impairment of gut motility. Both conditions have synergistic pathophysiologies that propagate neurodegenerative changes. Treatment options for GI symptoms in diabetic and Parkinson's disease patients are lacking. Anti-diabetic treatment improves motor symptoms in Parkinson's disease, however, its effect on GI symptoms is unclear.
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Affiliation(s)
- Yun Yan
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Georgia, Augusta University, 1120 15th Street, AD 2226, Augusta, GA, 30912, USA
| | - Dhanush Shimoga
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Georgia, Augusta University, 1120 15th Street, AD 2226, Augusta, GA, 30912, USA
| | - Amol Sharma
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Georgia, Augusta University, 1120 15th Street, AD 2226, Augusta, GA, 30912, USA.
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Zhang Q, Liu Y, Zhang Q, Zhang Y, Wu S, Jiang B, Ni M. Impaired Anorectal Afferents Is a Potential Pathophysiological Factor Associated to Functional Anorectal Pain. Front Neurol 2020; 11:577025. [PMID: 33162929 PMCID: PMC7581696 DOI: 10.3389/fneur.2020.577025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Accepted: 09/10/2020] [Indexed: 11/13/2022] Open
Affiliation(s)
- Qi Zhang
- Graduate School, Nanjing University of Chinese Medicine, Nanjing, China
| | - Yanni Liu
- Baoji City Hospital of Traditional Chinese Medicine, Baoji, China
| | - Qiong Zhang
- Shuyang County Hospital of Traditional Chinese Medicine, Suqian, China
| | - Yuqing Zhang
- Graduate School, Nanjing University of Chinese Medicine, Nanjing, China
| | - Sangsang Wu
- Graduate School, Nanjing University of Chinese Medicine, Nanjing, China
| | - Bin Jiang
- National Centre of Colorectal Disease, Nanjing Hospital of Chinese Medicine, Nanjing, China
| | - Min Ni
- National Centre of Colorectal Disease, Nanjing Hospital of Chinese Medicine, Nanjing, China
- *Correspondence: Min Ni
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Mundet L, Cabib C, Ortega O, Rofes L, Tomsen N, Marin S, Chacón C, Clavé P. Defective Conduction of Anorectal Afferents Is a Very Prevalent Pathophysiological Factor Associated to Fecal Incontinence in Women. J Neurogastroenterol Motil 2019; 25:423-435. [PMID: 31177647 PMCID: PMC6657934 DOI: 10.5056/jnm18196] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 03/01/2019] [Accepted: 03/26/2019] [Indexed: 12/13/2022] Open
Abstract
Background/Aims Fecal incontinence (FI) is a prevalent condition among women. While biomechanical motor components have been thoroughly researched, anorectal sensory aspects are less known. We studied the pathophysiology of FI in community-dwelling women, specifically, the conduction through efferent/afferent neural pathways. Methods A cross-sectional study was conducted on 175 women with FI and 19 healthy volunteers. The functional/structural study included anorectal manometry/endoanal ultrasound. Neurophysiological studies including pudendal nerve terminal motor latency (PNTML) and sensory-evoked-potentials to anal/rectal stimulation (ASEP/RSEP) were conducted on all healthy volunteers and on 2 subgroups of 42 and 38 patients, respectively. Results The main conditions associated with FI were childbirth (79.00%) and coloproctological surgery (37.10%). Cleveland score was 11.39 ± 4.09. Anorectal manometry showed external anal sphincter and internal anal sphincter insufficiency in 82.85% and 44.00%, respectively. Sensitivity to rectal distension was impaired in 27.42%. Endoanal ultrasound showed tears in external anal sphincter (60.57%) and internal anal sphincter disruptions (34.80%). Abnormal anorectal sensory conduction was evidenced through ASEP and RSEP in 63.16% and 50.00% of patients, respectively, alongside reduced activation of brain cortex to anorectal stimulation. In contrast, PNTML was delayed in only 33.30%. Stools were loose/very loose in 56.70% of patients. Conclusions Pathophysiology of FI in women is mainly associated with mechanical sphincter dysfunctions related to either muscle damage or, to a lesser extent, impaired efferent conduction at pudendal nerves. Impaired conduction through afferent anorectal pathways is also very prevalent in women with FI and may play an important role as a pathophysiological factor and as a potential therapeutic target.
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Affiliation(s)
- Lluís Mundet
- Unitat d'Exploracions Funcionals Digestives, Hospital de Mataró, Consorci Sanitari del Maresme, Mataró, Catalonia, Spain.,Centro de Investigación Biomédica en Red de enfermedades hepáticas y digestivas (CIBERehd), Instituto de Salud Carlos III, Barcelona, Spain
| | - Christopher Cabib
- Unitat d'Exploracions Funcionals Digestives, Hospital de Mataró, Consorci Sanitari del Maresme, Mataró, Catalonia, Spain
| | - Omar Ortega
- Unitat d'Exploracions Funcionals Digestives, Hospital de Mataró, Consorci Sanitari del Maresme, Mataró, Catalonia, Spain.,Centro de Investigación Biomédica en Red de enfermedades hepáticas y digestivas (CIBERehd), Instituto de Salud Carlos III, Barcelona, Spain
| | - Laia Rofes
- Unitat d'Exploracions Funcionals Digestives, Hospital de Mataró, Consorci Sanitari del Maresme, Mataró, Catalonia, Spain.,Centro de Investigación Biomédica en Red de enfermedades hepáticas y digestivas (CIBERehd), Instituto de Salud Carlos III, Barcelona, Spain
| | - Noemí Tomsen
- Unitat d'Exploracions Funcionals Digestives, Hospital de Mataró, Consorci Sanitari del Maresme, Mataró, Catalonia, Spain
| | - Sergio Marin
- Unitat d'Exploracions Funcionals Digestives, Hospital de Mataró, Consorci Sanitari del Maresme, Mataró, Catalonia, Spain
| | - Carla Chacón
- Unitat d'Exploracions Funcionals Digestives, Hospital de Mataró, Consorci Sanitari del Maresme, Mataró, Catalonia, Spain
| | - Pere Clavé
- Unitat d'Exploracions Funcionals Digestives, Hospital de Mataró, Consorci Sanitari del Maresme, Mataró, Catalonia, Spain.,Centro de Investigación Biomédica en Red de enfermedades hepáticas y digestivas (CIBERehd), Instituto de Salud Carlos III, Barcelona, Spain
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7
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Lee TH. Evaluation of Anorectal Afferent Pathway: Does It Help Overcome Unmet Diagnostic Needs in the Management of Fecal Incontinence? J Neurogastroenterol Motil 2019; 25:340-342. [PMID: 31327217 PMCID: PMC6657926 DOI: 10.5056/jnm19125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 07/08/2019] [Indexed: 01/20/2023] Open
Affiliation(s)
- Tae Hee Lee
- Institute for Digestive Research, Soonchunhyang University Seoul Hospital, Seoul, Korea
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8
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Nissen TD, Brock C, Lykkesfeldt J, Lindström E, Hultin L. Pharmacological modulation of colorectal distension evoked potentials in conscious rats. Neuropharmacology 2018; 140:193-200. [PMID: 30059662 DOI: 10.1016/j.neuropharm.2018.07.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 07/02/2018] [Accepted: 07/24/2018] [Indexed: 12/30/2022]
Abstract
BACKGROUND Cerebral evoked potentials (CEP) induced by colorectal distension (CRD) in conscious rats provides a novel method in studies of visceral sensitivity. The aim of this study was to explore the pharmacological effect on CEP of compounds known to reduce the visceromotor response to CRD. METHODS Epidural electrodes were chronically implanted in eight female Sprague-Dawley rats. Evoked potentials were elicited by colorectal rapid balloon distensions (100 ms, 80 mmHg) and the effect of WIN55 (cannabinoid CB receptor agonist), clonidine (adrenergic α2 receptor agonist), MPEP (mGluR5 receptor antagonist), pregabalin (ligand of α2δ subunits in voltage-gated calcium channels) and baclofen (GABA-B receptor agonist) on amplitudes and latency of CEP were determined. RESULTS WIN55 (0.1 μmol kg-1), clonidine (0.05 μmol kg-1), MPEP (10 μmol kg-1) and pregabalin (200 μmol kg-1) caused a significant, p < 0.05, reduction of the N2 to P2 peak-to-peak amplitude by 23 ± 8%, 25 ± 8%, 39 ± 5%, and 47 ± 6% respectively. Baclofen (9 μmol kg-1) induced a prolongation of the N2 peak latency of 18 ± 4% but had no significant effect on the amplitudes. CONCLUSION The obtained results suggest that MPEP, WIN55, clonidine, and pregabalin reduce visceral nociceptive input to the brain, whereas the lack of effect of baclofen on CRD evoked CEP amplitudes suggest that the effect on VMR is not due to a direct analgesic effect. Brain responses to colorectal distension provide a useful tool to evaluate pharmacological effects in rats and may serve as a valuable preclinical model for understanding pharmacological mechanisms related to visceral sensitivity.
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Affiliation(s)
- Thomas Dahl Nissen
- Laboratory Animal Sciences, Drug Safety and Metabolism, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden; Mech-Sense, Department of Gastroenterology & Hepatology, Aalborg University Hospital, Aalborg, Denmark; Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Christina Brock
- Mech-Sense, Department of Gastroenterology & Hepatology, Aalborg University Hospital, Aalborg, Denmark
| | - Jens Lykkesfeldt
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Leif Hultin
- Laboratory Animal Sciences, Drug Safety and Metabolism, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden.
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Sharma A, Kurek J, Morgan JC, Wakade C, Rao SSC. Constipation in Parkinson's Disease: a Nuisance or Nuanced Answer to the Pathophysiological Puzzle? Curr Gastroenterol Rep 2018; 20:1. [PMID: 29350301 DOI: 10.1007/s11894-018-0609-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
PURPOSE OF REVIEW Chronic constipation is a common, nonmotor, and prodromal symptom in Parkinson's disease (PD). Its underlying neuropathology may provide pathophysiological insight into PD. Here, we critically review what is currently known about the neuroanatomical and brain-gut interactions, and the origin and progression of Lewy pathology (LP) at three levels-brain/brainstem, spinal cord, and enteric nervous system. RECENT FINDINGS Many recent studies have illustrated the challenges of examining LP in tissues obtained from colon biopsies of PD patients. Large-scale epidemiological studies have not confirmed the widely accepted Braakpostula. In this review, we propose an alternative origin and route of spread of LP in PD. We describe novel, noninvasive neurophysiological testing that could advance the understanding of LP and complex bidirectional brain-pelvic floor neural pathways in PD-a true disease model of a neurogastrointestinal disorder. This review may provide the impetus for future studies investigating gut and brain interaction and constipation in PD.
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Affiliation(s)
- Amol Sharma
- Division of Gastroenterology/Hepatology, Medical College of Georgia, Augusta University Medical Center, 1120 15th Street, AD-2226, Augusta, GA, 30912, USA.
| | - Julie Kurek
- Parkinson's Foundation Center of Excellence, Movement Disorders Program, Department of Neurology, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - John C Morgan
- Parkinson's Foundation Center of Excellence, Movement Disorders Program, Department of Neurology, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Chandramohan Wakade
- Department of Physical Therapy, College of Allied Health Sciences, Augusta University & Charlie Norwood VAMC, Augusta, GA, USA
| | - Satish S C Rao
- Division of Gastroenterology/Hepatology, Medical College of Georgia, Augusta University Medical Center, 1120 15th Street, AD-2226, Augusta, GA, 30912, USA
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10
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Lelic D, Nissen TD, Brock C, Aziz Q, Drewes AM. Rapid balloon distension as a tool to study cortical processing of visceral sensations and pain. Neurogastroenterol Motil 2015; 27:832-40. [PMID: 26011783 DOI: 10.1111/nmo.12557] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 02/27/2015] [Indexed: 12/12/2022]
Abstract
BACKGROUND The processing of discomfort and pain in the central nervous system is normally studied with experimental methods, but it is mandatory that they are reliable over time to ensure that any interventions will result in valid results. We investigated reliability of rapid balloon distension in the rectum to elicit cortical evoked potentials (CEPs) to study the reliability of central processing of visceral sensation and discomfort/pain. METHODS Eighteen healthy volunteers had two series of rectal balloon distensions performed on two separate days. Individualized balloon pressure, corresponding to pain detection threshold or to the maximum possible distension (30 psi), was used. Within- and between days reliability was measured in terms of amplitudes and latencies of the CEP global field power, topography and underlying brain networks. KEY RESULTS There were two prominent peaks in the CEP recordings at mean latencies of 157 and 322 ms. There were no differences in latencies or amplitudes (p = 0.3) and they passed the Bland-Altman test for reproducibility. There were no differences in topographies (p > 0.7). Brain source connectivity revealed the cingulate-operculum network as the most consistent network within and between subjects. There were no differences in the location of brain sources in this network (p = 0.9) and the source coordinates were reproducible. Finally, the cingulate source generally had higher strength than operculum source (p < 0.001). CONCLUSIONS & INFERENCES A reliable method to study central mechanisms underlying visceral sensation and pain was established. The method may improve our understanding of visceral pain and could be an objective method for studying efficacy of analgesics on visceral pain.
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Affiliation(s)
- D Lelic
- Mech-Sense, Department of Gastroenterology & Hepatology, Aalborg University Hospital, Aalborg, Denmark
| | - T D Nissen
- Department of Clinical Medicine, Aalborg University, Aalborg, Denmark
| | - C Brock
- Mech-Sense, Department of Gastroenterology & Hepatology, Aalborg University Hospital, Aalborg, Denmark
| | - Q Aziz
- Centre for Digestive Diseases, Blizard Institute, The Wingate Institute of Neurogastroenterology, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - A M Drewes
- Mech-Sense, Department of Gastroenterology & Hepatology, Aalborg University Hospital, Aalborg, Denmark.,Department of Clinical Medicine, Aalborg University, Aalborg, Denmark.,Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark
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11
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Meyer I, Richter HE. An Evidence-Based Approach to the Evaluation, Diagnostic Assessment and Treatment of Fecal Incontinence in Women. CURRENT OBSTETRICS AND GYNECOLOGY REPORTS 2014; 3:155-164. [PMID: 25505643 PMCID: PMC4258837 DOI: 10.1007/s13669-014-0085-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Fecal incontinence (FI) is a debilitating disorder which negatively impacts quality of life. The etiology is often multifactorial and although most women with FI are able to be treated, many remain untreated because a significant proportion of women do not report their symptoms and seek care. The evaluation and treatment of FI can be also hindered by a lack of understanding of the mechanisms and current options. This article provides a review on the evidence-based evaluation and management for FI.
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Affiliation(s)
- Isuzu Meyer
- Division of Urogynecology and Pelvic Reconstructive Surgery, Department of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, AL, 1700 6th Avenue South, Suite 10382, Birmingham, AL 35233, ,
| | - Holly E Richter
- Division of Urogynecology and Pelvic Reconstructive Surgery, Department of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, AL, 1700 6th Avenue South, Suite 10382, Birmingham, AL 35233, ,
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Haas S, Brock C, Krogh K, Gram M, Nissen TD, Lundby L, Laurberg S, Drewes AM. Cortical evoked potentials in response to rapid balloon distension of the rectum and anal canal. Neurogastroenterol Motil 2014; 26:862-73. [PMID: 24750321 DOI: 10.1111/nmo.12341] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 03/11/2014] [Indexed: 02/08/2023]
Abstract
BACKGROUND Neurophysiological evaluation of anorectal sensory function is hampered by a paucity of methods. Rapid balloon distension (RBD) has been introduced to describe the cerebral response to rectal distension, but it has not successfully been applied to the anal canal. METHODS Nineteen healthy women received 30 RBDs in the rectum and the anal canal at intensities corresponding to sensory and unpleasantness thresholds, and response was recorded as cortical evoked potentials (CEPs) in 64-channels. The anal canal stimulations at unpleasantness level were repeated after 4 min to test the within-day reproducibility. CEPs were averaged, and to overcome latency variation related to jitter the spectral content of single sweeps was also computed. KEY RESULTS Repeated stimulation of the anal canal generated CEPs with similar latencies but smaller amplitudes compared to those from the rectum. Due to latency jitter, reproducibility of averaged CEPs was lower than what was found in the rectum. The most reproducible feature was N2P2 peak-to-peak amplitude with intra-class correlation coefficient (ICC) of 0.7 and coefficient of variation (CV) of 18%. Spectral content of the single sweeps showed reproducibility with ICCs for all bands >0.8 and corresponding CVs <7%. CONCLUSIONS & INFERENCES Cortical potentials evoked from the anal canal are challenged by latency jitter likely related to variability in muscle tone due to the distensions. Using single-sweep analysis, anal CEPs proved to be reproducible and should be used in future evaluation of the anal function.
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Affiliation(s)
- S Haas
- Department of Surgery, Aarhus University Hospital, Aarhus, Denmark
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13
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Nissen TD, Brock C, Graversen C, Coen SJ, Hultin L, Aziz Q, Lykkesfeldt J, Drewes AM. Translational aspects of rectal evoked potentials: a comparative study in rats and humans. Am J Physiol Gastrointest Liver Physiol 2013; 305:G119-28. [PMID: 23703652 PMCID: PMC3725684 DOI: 10.1152/ajpgi.00403.2012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Inconsistencies between species has stunted the progress of developing new analgesics. To increase the success of translating results between species, improved comparable models are required. Twelve rats received rectal balloon distensions on 2 different days separated by 24.3 (SD 24.6) days. Rectal balloon distensions were also performed in 18 humans (mean age: 34 yr; range: 21-56 yr; 12 men) on two separate occasions, separated by 9.3 (SD 5.5) days. In rats, cerebral evoked potentials (CEPs) were recorded by use of implanted skull-electrodes to distension pressure of 80 mmHg. In humans surface electrodes and individualized pressure, corresponding to pain detection threshold, were used. Comparison of morphology was assessed by wavelet analysis. Within- and between-day reproducibility was assessed in terms of latencies, amplitudes, and frequency content. In rats CEPs showed triphasic morphology. No differences in latencies, amplitudes, and power distribution were seen within or between days (all P ≥ 0.5). Peak-to-peak amplitude between the first positive and negative potential were the most reproducible characteristic within and between days (evaluated by intraclass correlation coefficients, ICC) (ICC = 0.99 and ICC = 9.98, respectively). In humans CEPs showed a triphasic morphology. No differences in latencies, amplitudes, or power distribution were seen within or between days (all P ≥ 0.2). Latency to the second negative potential (ICC = 0.98) and the second positive potential (ICC = 0.95) was the most reproducible characteristic within and between days. A unique and reliable translational platform was established assessing visceral sensitivity in rats and humans, which may improve the translational process of developing new drugs targeting visceral pain.
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Affiliation(s)
- Thomas Dahl Nissen
- 1Section of Biomedicine, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; ,2Biomedical Research Laboratory, Aalborg Hospital, Aarhus University Hospital, Aalborg, Denmark; ,3Mech-Sense, Department of Gastroenterology and Hepatology, Aalborg Hospital, Aarhus University Hospital, Aalborg, Denmark;
| | - Christina Brock
- 3Mech-Sense, Department of Gastroenterology and Hepatology, Aalborg Hospital, Aarhus University Hospital, Aalborg, Denmark;
| | - Carina Graversen
- 4Mech-Sense, Department of Radiology, Aalborg Hospital, Aarhus University Hospital, Aalborg, Denmark;
| | - Steven J. Coen
- 5Kings College London, Institute of Psychiatry, Department of Neuroimaging, London, United Kingdom;
| | - Leif Hultin
- 6Bioscience, AstraZeneca R&D, Mölndal, Sweden;
| | - Qasim Aziz
- 7Centre for Digestive Diseases, Blizard Institute, The Wingate Neurogastroenterology Group, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom; and
| | - Jens Lykkesfeldt
- 1Section of Biomedicine, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark;
| | - Asbjørn Mohr Drewes
- 8Center for Sensory-Motor Interactions, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
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14
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Burgell RE, Lelic D, Carrington EV, Lunniss PJ, Olesen SS, Surguy S, Drewes AM, Scott SM. Assessment of rectal afferent neuronal function and brain activity in patients with constipation and rectal hyposensitivity. Neurogastroenterol Motil 2013; 25:260-7, e167-8. [PMID: 23240734 DOI: 10.1111/nmo.12047] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Blunted rectal sensation (rectal hyposensitivity: RH) is present in almost one-quarter of patients with chronic constipation. The mechanisms of its development are not fully understood, but in a proportion, afferent dysfunction is likely. To determine if, in patients with RH, alteration of rectal sensory pathways exists, rectal evoked potentials (EPs) and inverse modeling of cortical dipoles were examined. METHODS Rectal EPs (64 channels) were recorded in 13 patients with constipation and RH (elevated thresholds to balloon distension) and 11 healthy controls, in response to electrical stimulation of the rectum at 10 cm from the anal verge using a bipolar stimulating electrode. Stimuli were delivered at pain threshold. Evoked potential peak latencies and amplitudes were analyzed, and inverse modeling was performed on traces obtained to determine the location of cortical generators. KEY RESULTS Pain threshold was higher in patients than controls [median 59 (range 23-80) mA vs 24 (10-55) mA; P = 0.007]. Median latency to the first negative peak was 142 (±24) ms in subjects compared with 116 (±15) ms in controls (P = 0.004). There was no difference in topographic analysis of EPs or location of cortical activity demonstrated by inverse modeling between groups. CONCLUSIONS & INFERENCES This study is the first showing objective evidence of alteration in the rectal afferent pathway of individuals with RH and constipation. Prolonged latencies suggest a primary defect in sensory neuronal function, while cerebral processing of visceral sensory information appears normal.
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Affiliation(s)
- R E Burgell
- Academic Surgical Unit (GI Physiology Unit), Blizard Institute, Barts, UK
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15
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Burgell RE, Scott SM. Rectal hyposensitivity. J Neurogastroenterol Motil 2012; 18:373-84. [PMID: 23105997 PMCID: PMC3479250 DOI: 10.5056/jnm.2012.18.4.373] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 09/05/2012] [Accepted: 09/13/2012] [Indexed: 01/20/2023] Open
Abstract
Impaired or blunted rectal sensation, termed rectal hyposensitivity (RH), which is defined clinically as elevated sensory thresholds to rectal balloon distension, is associated with disorders of hindgut function, characterised primarily by symptoms of constipation and fecal incontinence. However, its role in symptom generation and the pathogenetic mechanisms underlying the sensory dysfunction remain incompletely understood, although there is evidence that RH may be due to 'primary' disruption of the afferent pathway, 'secondary' to abnormal rectal biomechanics, or to both. Nevertheless, correction of RH by various interventions (behavioural, neuromodulation, surgical) is associated with, and may be responsible for, symptomatic improvement. This review provides a contemporary overview of RH, focusing on diagnosis, clinical associations, pathophysiology, and treatment paradigms.
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Affiliation(s)
- Rebecca E Burgell
- Academic Surgical Unit (GI Physiology Unit), Wingate Institute and Neurogastroenterology Group, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
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16
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Abstract
Human defecation involves integrated and coordinated sensorimotor functions, orchestrated by central, spinal, peripheral (somatic and visceral), and enteric neural activities, acting on a morphologically intact gastrointestinal tract (including the final common path, the pelvic floor, and anal sphincters). The multiple factors that ultimately result in defecation are best appreciated by describing four temporally and physiologically fairly distinct phases. This article details our current understanding of normal defecation, including recent advances, but importantly identifies those areas where knowledge or consensus is still lacking. Appreciation of normal physiology is central to directed treatment of constipation and also of fecal incontinence, which are prevalent in the general population and cause significant morbidity.
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Affiliation(s)
- Somnath Palit
- Academic Surgical Unit (GI Physiology Unit), Barts and the London School of Medicine and Dentistry, Blizard Institute, Queen Mary University, London, UK.
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17
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Model for Electrical Field Distribution in the Human Esophagus during Stimulation with Patch and Ring Electrodes. Gastroenterol Res Pract 2011; 2011:562592. [PMID: 22144995 PMCID: PMC3227507 DOI: 10.1155/2011/562592] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Accepted: 08/29/2011] [Indexed: 11/23/2022] Open
Abstract
Introduction. Electrical stimulation is used in experimental human pain models. The aim was to develop a model that visualizes the distribution of electrical field in the esophagus close to ring and patch electrodes mounted on an esophageal catheter and to explain the obtained sensory responses.
Methods. Electrical field distribution in esophageal layers (mucosa, muscle layers, and surrounding tissue) was computed using a finite element model based on a 3D model. Each layer was assigned different electrical properties. An electrical field exceeding 20 V/m was considered to activate the esophageal afferents. Results. The model output showed homogeneous and symmetrical field surrounding ring electrodes compared to a saddle-shaped field around patch electrodes. Increasing interelectrode distance enlarged the electrical field in muscle layer.
Conclusion. Ring electrodes with 10 mm interelectrode distance seem optimal for future catheter designs. Though the model needs further validation, the results seem useful for electrode designs and understanding of electrical stimulation patterns.
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18
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Arebi N, Bullas DC, Dukes GE, Gurmany S, Hicks KJ, Kamm MA, Hobson AR. Distinct neurophysiological profiles in irritable bowel syndrome. Am J Physiol Gastrointest Liver Physiol 2011; 300:G1086-93. [PMID: 21350185 DOI: 10.1152/ajpgi.00553.2010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The objective of this study was to determine whether cortical evoked potentials (CEPs) can define neurophysiological patterns in irritable bowel syndrome (IBS). In this prospective study of consecutive patients attending secondary and tertiary centers, patients with Rome II-defined IBS underwent rectal sensory and pain threshold (RST and RPT, respectively) testing with electrical stimulation on three separate visits. CEPs were collated for 75% pain thresholds, and anxiety [Spielberger State-Trait Anxiety Inventory (SSTAI)] questionnaires were completed. Subjects were 33 IBS patients (27 female, mean age 40.1 yr) and 21 healthy controls (14 female, mean age 31.4 yr). At visit 3, RPT was significantly lower [mean (95% CI)] in IBS patients than in control subjects: 58.2 mA (48.0-68.5) vs. 79.5 mA (69.3-89.6) (P < 0.01). No significant differences were observed in CEP latencies and amplitudes between visits 1, 2, and 3 within each group, except P2 latency for controls (P = 0.04) and N2 latency (P = 0.04) and N2 amplitude (P = 0.02) for IBS patients. Group comparisons showed significant differences in 3-day mean RPT, CEP amplitudes, and CEP latencies between IBS patients and controls. RPT <50 mA and P1 latency >106 ms were identified four IBS subgroups: 24% were hypersensitive, 12% were hypervigilant, 15% were hyposensitive, and 49% exhibited normal P1 latency and pain threshold. CEPs are reliable and reproducible measures of early sensory processing. Identification of four IBS neurophysiological patterns highlights its heterogeneous nature. These findings mark the first step toward personalized medicine in IBS, whereby therapy may be directed at the underlying physiological process.
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Affiliation(s)
- Naila Arebi
- Gastrointestinal Physiology Department, St. Mark’s Hospital Campus, Imperial College, Harrow, Middlesex, UK.
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19
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Remes-Troche JM, Tantiphlachiva K, Attaluri A, Valestin J, Yamada T, Hamdy S, Rao SSC. A bi-directional assessment of the human brain-anorectal axis. Neurogastroenterol Motil 2011; 23:240-8, e117-8. [PMID: 20964791 PMCID: PMC3035753 DOI: 10.1111/j.1365-2982.2010.01619.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND Brain-gut dysfunction has been implicated in gastrointestinal disorders but a comprehensive test of brain-gut axis is lacking. We developed and tested a novel method for assessing both afferent anorectal-brain function using cortical evoked potentials (CEP), and efferent brain-anorectal function using motor evoked potentials (MEP). METHODS Cortical evoked potentials was assessed following electrical stimulations of anus and rectum with bipolar electrodes in 26 healthy subjects. Anorectal MEPs were recorded following transcranial magnetic stimulation (TMS) over paramedian motor cortices bilaterally. Anal and rectal latencies/amplitudes for CEP and MEP responses and thresholds for first sensation and pain (mA) were analyzed and compared. Reproducibility and interobserver agreement of responses were examined. KEY RESULTS Reproducible polyphasic rectal and anal CEPs were recorded in all subjects, without gender differences, and with negative correlation between BMI and CEP amplitude (r -0.66, P=0.001). Transcranial magnetic stimulation evoked triphasic rectal and anal MEPs, without gender differences. Reproducibility for CEP and MEP was excellent (CV <10%). The inter-rater CV for anal and rectal MEPs was excellent (ICC 97-99), although there was inter-subject variation. CONCLUSIONS & INFERENCES Combined CEP and MEP studies offer a simple, inexpensive and valid method of examining bidirectional brain-anorectal axes. This comprehensive method could provide mechanistic insights into lower gut disorders.
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Affiliation(s)
- J M Remes-Troche
- Division of Neurogastroenterology and Motility, Department of Internal Medicine and Clinical Translational Research Center, University of Iowa Carver College of Medicine, Iowa City, IA, USA
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20
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Garvin B, Lovely L, Tsodikov A, Minecan D, Hong S, Wiley JW. Cortical and spinal evoked potential response to electrical stimulation in human rectum. World J Gastroenterol 2010; 16:5440-6. [PMID: 21086561 PMCID: PMC2988236 DOI: 10.3748/wjg.v16.i43.5440] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To study a novel technique to record spinal and cortical evoked potentials (EPs) simultaneously in response to electrical stimulation in the human rectum.
METHODS: Eight male and nine female healthy volunteers participated. Stimulating electrodes were attached to the rectal mucosa at 15 cm and 12 cm above the dentate line. Recording skin electrodes were positioned over vertebrae L4 through S2. The electrical stimulus was a square wave of 0.2 ms duration and the intensity of the stimulus varied between 0 and 100 mA. EP responses were recorded using a Nicolet Viking IV programmable signal conditioner.
RESULTS: Simultaneous recording of cortical and spinal EPs was obtained in > 80% of the trials. The EP responses increased with the intensity of the electrical stimulation, were reproducible overtime, and were blocked by application of Lidocaine jelly at the site of stimulation. The morphology (N1/P1), mean ± SD for latency (spinal N1, 4.6 ± 0.4 ms; P1, 6.8 ± 0.5 ms; cortical N1, 136.1 ± 4.2 ms; P1, 233.6 ± 12.8 ms) and amplitude (N1/P1, spinal, 38 ± 7 μV; cortical 19 ± 3 μV) data for the EP responses were consistent with those in the published literature. Reliable and reproducible EP recordings were obtained with the attachment of the electrodes to the rectal mucosa at predetermined locations between 16 and 8 cm above the anal verge, and the distance between the attachment sites of the electrodes (the optimal distance being approximately 3.0 cm between the two electrodes).
CONCLUSION: This technique can be used to assess potential abnormalities in primary afferent neural pathways innervating the rectum in several neurodegenerative and functional pain disorders.
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Abstract
Visceral hypersensitivity is regarded as an important factor in the pathogenesis of functional gastrointestinal disorders. Assessment of visceral sensitivity has several important aims: increasing the understanding of normal and abnormal visceral sensory mechanisms and participating sensory pathways, serving as diagnostic tool to detect patients with abnormal visceral sensitivity, and evaluating therapeutic interventions directed towards modification of visceral sensitivity. Current stimulation modes in sensitivity tests include mechanical distension by barostat or tensostat, nutrient drink or water load, chemical stimulation, e.g. acid provocation or capsaicin ingestion, electrical, or thermal stimulation. Multimodal probes incorporating several stimulation modes in one device have recently been developed. Assessment of visceral sensation can be based on subjective responses of conscious perception or on objective parameters such as visceromotoric responses or central sensory processing patterns. All methods face the challenge that visceral sensitivity may be influenced by a wide spectrum of different factors, including the test techniques themselves, and improved, preferably non-invasive sensitivity tests with a greater standardisation and a broader applicability are still needed.
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Affiliation(s)
- Viola Andresen
- Israelitic Hospital, Orchideenstieg 14, 22297 Hamburg, Germany.
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22
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Scott SM, Gladman MA. Manometric, sensorimotor, and neurophysiologic evaluation of anorectal function. Gastroenterol Clin North Am 2008; 37:511-38, vii. [PMID: 18793994 DOI: 10.1016/j.gtc.2008.06.010] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
With advances in diagnostic technology, it is now accepted that in the field of functional bowel disorders, symptom-based assessment is unsatisfactory as the sole means of directing therapy. A robust taxonomy based on underlying pathophysiology has been suggested, highlighting a crucial role for physiologic testing in clinical practice. A wide number of complementary investigations currently exist for the assessment of anorectal structure and function, some of which have a clinical impact in patients with functional disorders of evacuation and continence by markedly improving diagnostic yield and altering management. The techniques, limitations, measurements, and clinical use of manometric, sensorimotor, and neurophysiologic tests of anorectal function are presented.
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Affiliation(s)
- S Mark Scott
- GI Physiology Unit and Neurogastroenterology Group (Centre for Academic Surgery), Institute of Cell and Molecular Science, Barts, London, UK.
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23
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Hamdy S. More than a gut feeling: the human visceral brain re-visited. Neurogastroenterol Motil 2008; 20:577-9. [PMID: 18410264 DOI: 10.1111/j.1365-2982.2008.01123.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- S Hamdy
- School of Translation Medicine-GI Sciences, Faculty of Medical and Human Sciences, University of Manchester, Clinical Sciences Building, Salford Royal NHS Foundation Trust, Salford, Manchester, UK.
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24
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25
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Abstract
Neurophysiological tests of anorectal function can provide useful information regarding the integrity of neuronal innervation, as well as neuromuscular function. This information can give insights regarding the pathophysiological mechanisms that lead to several disorders of anorectal function, particularly fecal incontinence, pelvic floor disorders and dyssynergic defecation. Currently, several tests are available for the neurophysiological evaluation of anorectal function. These tests are mostly performed on patients referred to tertiary care centers, either following negative evaluations or when there is lack of response to conventional therapy. Judicious use of these tests can reveal significant and new understanding of the underlying mechanism(s) that could pave the way for better management of these disorders. In addition, these techniques are complementary to other modalities of investigation, such as pelvic floor imaging. The most commonly performed neurophysiological tests, along with their indications and clinical utility are discussed. Several novel techniques are evolving that may reveal new information on brain-gut interactions.
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Affiliation(s)
- Jose M Remes-Troche
- Digestive Physiology and Motility Department, Medical-Biological Research Institute, University of Veracruz, Veracruz, Mexico, Tel.: +52 229 202 1231, Fax: +52 229 202 1231
| | - Satish SC Rao
- Section of Neuro gastroenterology, Division of Gastroenterology–Hepatology, Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, IA 52242, USA, Tel.: +1 319 353 6602, Fax: +1 319 353 6399
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Murrell JC, Mitchinson SL, Johnstone AC, Johnson CB, Barnes GRG. Is it possible to generate cerebral evoked potentials with a mechanical stimulus from the duodenum in rats? J Neurosci Methods 2007; 162:215-21. [PMID: 17320970 DOI: 10.1016/j.jneumeth.2007.01.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2006] [Revised: 01/17/2007] [Accepted: 01/20/2007] [Indexed: 11/16/2022]
Abstract
The study aim was to develop a model to generate cerebral evoked potentials (CEPs) by mechanical distention of the duodenum in rats. Twenty Sprague-Dawley rats were anaesthetized and the EEG recorded from the left and right somatosensory cortices (S1L, S1R). A balloon catheter was implanted into the duodenum. A pneumatic device, triggered by data acquisition software, inflated the balloon for 200 ms every 3s to deliver a repeatable noxious stimulus. EEG was recorded for 100 ms before and 500 ms after onset of inflation and the response to 512 stimuli averaged to generate a CEP. Two CEPs were generated in each animal and data summed to calculate a single CEP for each channel. Data were excluded when the signal to noise ratio was < 2, therefore data are presented from 11 animals. A repeatable CEP was identified in waveforms recorded from S1L. The mean (S.D.) CEP comprised a triphasic waveform (P1, N1, P2) with latencies of 246.0 (24.7), 289.3 (12.8) and 321.5 (13.2)ms, respectively. We are the first group to have generated and characterized a CEP following mechanical stimulation of the duodenum. This model can be applied to further elucidate the mechanisms leading to visceral pain perception.
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Affiliation(s)
- Joanna C Murrell
- Institute of Veterinary Animal and Biomedical Sciences, College of Sciences, Massey University, Private Bag 11 222, Palmerston North, New Zealand.
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27
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Drewes AM, Dimcevski G, Sami SAK, Funch-Jensen P, Huynh KD, Le Pera D, Arendt-Nielsen L, Valeriani M. The "human visceral homunculus" to pain evoked in the oesophagus, stomach, duodenum and sigmoid colon. Exp Brain Res 2006; 174:443-52. [PMID: 16676165 DOI: 10.1007/s00221-006-0480-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2006] [Accepted: 03/28/2006] [Indexed: 12/24/2022]
Abstract
The oesophagus, stomach, duodenum and sigmoid colon were electrically stimulated in 12 healthy volunteers with a thin nasal endoscope. The painful cortical evoked potentials (EPs) were recorded from 64 surface electrodes. The early EPs with latencies < 200 ms were studied and the corresponding dipole sources were calculated. The electrical current intensities needed to evoke pain were highest in the stomach and duodenum, compared to the other segments (F = 7.8; P < 0.001; post hoc analysis P < 0.05). The EP latencies after stimulation of the stomach and sigmoid colon were shorter compared with those to stimulation of the oesophagus and duodenum (all P values < 0.001). The EP amplitudes were higher to oesophagus stimulation (all P values < 0.001 except for the early positivity). The potential fields obtained after stimulation of the most distal segments (duodenum and sigmoid colon) were in general distributed more posteriorly compared to those recorded in the more proximal regions. The EP topographies to stimulation of all gut tracts were explained by a bilateral source in the second somatosensory (SII) area, by a dipole in the anterior cingulate cortex (ACC), and by a bilateral generator in the insular cortex. However, the position of the sources significantly changed depending on the stimulated gut tract. Moreover, while the SII and ACC sources were initially activated to oesophagus and stomach stimulation, the ACC and insular activities were the earliest ones after stimulation of the lower gut segments. The findings reflect differences in pathways and brain processing of visceral nociceptive inputs coming from either upper or lower gut and may improve our understanding of the brain-gut axis in health and disease.
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Affiliation(s)
- Asbjørn Mohr Drewes
- Center for Visceral Biomechanics and Pain, Department of Gastroenterology, Aalborg University Hospital, Aalborg, Denmark
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28
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Yang M, Li ZS, Xu XR, Fang DC, Zou DW, Xu GM, Sun ZX, Tu ZX. Characterization of cortical potentials evoked by oesophageal balloon distention and acid perfusion in patients with functional heartburn. Neurogastroenterol Motil 2006; 18:292-9. [PMID: 16553584 DOI: 10.1111/j.1365-2982.2006.00761.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Oesophageal visceral hypersensitivity is thought to be important in generating symptoms in functional heartburn (FH). However, the neurophysiological mechanisms involved are poorly understood. The aim of this study was to compare the characteristics of oesophageal cortical evoked potentials (CEPs) induced by balloon distension and acid perfusion in FH and controls. We studied 21 FH patients and 12 healthy volunteers. Oesophageal mechanical stimulation was performed using the specially constructed mechanical pump. CEPs were recorded using the 10-20 international system of electroencephalogram recording. Oesophageal distention elicited recognizable, reproducible and muti-peak CEPs. CEP latencies for N1, P1 and N2 components were significantly shorter (P = 0.016, P = 0.003 and P = 0.031, respectively) in FH than in controls before perfusion. Acid perfusion significantly decreased the latencies of N1, P1 and N2 (P = 0.022, P = 0.007 and P = 0.041, respectively) and significantly increased the amplitude of P1-N2 components (P = 0.020) in FH patients, but not in controls. In conclusion, cortical evoked potential responses evoked by oesophageal distention and acid perfusion were greater in FH than in controls, suggesting that dysfunction of visceral neural pathways and/or alterations in cortical processing may produce and mediate oesophageal hypersensitivity in FH. These findings provide the evidence that central sensitization contributes to the development and maintenance of oesophageal hypersensitivity.
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Affiliation(s)
- M Yang
- Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China
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29
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Andresen V, Bach DR, Poellinger A, Tsrouya C, Stroh A, Foerschler A, Georgiewa P, Zimmer C, Mönnikes H. Brain activation responses to subliminal or supraliminal rectal stimuli and to auditory stimuli in irritable bowel syndrome. Neurogastroenterol Motil 2005; 17:827-37. [PMID: 16336498 DOI: 10.1111/j.1365-2982.2005.00720.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Visceral hypersensitivity in irritable bowel syndrome (IBS) has been associated with altered cerebral activations in response to visceral stimuli. It is unclear whether these processing alterations are specific for visceral sensation. In this study we aimed to determine by functional magnetic resonance imaging (fMRI) whether cerebral processing of supraliminal and subliminal rectal stimuli and of auditory stimuli is altered in IBS. In eight IBS patients and eight healthy controls, fMRI activations were recorded during auditory and rectal stimulation. Intensities of rectal balloon distension were adapted to the individual threshold of first perception (IPT): subliminal (IPT -10 mmHg), liminal (IPT), or supraliminal (IPT +10 mmHg). IBS patients relative to controls responded with lower activations of the prefrontal cortex (PFC) and anterior cingulate cortex (ACC) to both subliminal and supraliminal stimulation and with higher activation of the hippocampus (HC) to supraliminal stimulation. In IBS patients, not in controls, ACC and HC were also activated by auditory stimulation. In IBS patients, decreased ACC and PFC activation with subliminal and supraliminal rectal stimuli and increased HC activation with supraliminal stimuli suggest disturbances of the associative and emotional processing of visceral sensation. Hyperreactivity to auditory stimuli suggests that altered sensory processing in IBS may not be restricted to visceral sensation.
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Affiliation(s)
- V Andresen
- Department of Medicine, Division of Hepatology, Gastroenterology, and Endocrinology, Charité- Universitätsmedizin Berlin, Berlin, Germany
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30
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Abstract
Functional abdominal pain or functional abdominal pain syndrome (FAPS) is an uncommon functional gut disorder characterised by chronic or recurrent abdominal pain attributed to the gut but poorly related to gut function. It is associated with abnormal illness behaviour and patients show psychological morbidity that is often minimised or denied in an attempt to discover an organic cause for symptoms. Thus the conventional biomedical approach to the management of such patients is unhelpful and a person's symptom experience is more usefully investigated using a biopsychosocial evaluation, which necessarily entails a multidisciplinary system of healthcare provision. Currently the pathophysiology of the disorder is poorly understood but is most likely to involve a dysfunction of central pain mechanisms either in terms of attentional bias, for example, hypervigilance or a failure of central pain modulation/inhibition. Although modern neurophysiological investigation of patients is promising and may provide important insights into the pathophysiology of FAPS, current clinical management relies on an effective physician-patient relationship in which limits on clinical investigation are set and achievable treatment goals tailored to the patient's needs are pursued.
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Affiliation(s)
- P J Matthews
- Department of Gastrointestinal Sciences, Hope Hospital, University of Manchester, Manchester M6 8HD, UK
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Bielefeldt K, Christianson JA, Davis BM. Basic and clinical aspects of visceral sensation: transmission in the CNS. Neurogastroenterol Motil 2005; 17:488-99. [PMID: 16078937 DOI: 10.1111/j.1365-2982.2005.00671.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Pain and discomfort are the leading cause for consultative visits to gastroenterologists. Acute pain should be considered a symptom of an underlying disease, thereby serving a physiologically important function. However, many patients experience chronic pain in the absence of potentially harmful stimuli or disorders, turning pain into the primary problem rather than a symptom. Vagal and spinal afferents both contribute to the sensory component of the gut-brain axis. Current evidence suggests that they convey different elements of the complex sensory experience. Spinal afferents play a key role in the discriminatory dimension, while vagal input primarily affects the strong emotional and autonomic reactions to noxious visceral stimuli. Drugs, surgical and non-pharmacological treatments can target these pathways and provide therapeutic options for patients with chronic visceral pain syndromes.
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Affiliation(s)
- K Bielefeldt
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA.
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Hobson AR, Furlong PL, Worthen SF, Hillebrand A, Barnes GR, Singh KD, Aziz Q. Real-time imaging of human cortical activity evoked by painful esophageal stimulation. Gastroenterology 2005; 128:610-9. [PMID: 15765397 DOI: 10.1053/j.gastro.2004.12.033] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND & AIMS Current models of visceral pain processing derived from metabolic brain imaging techniques fail to differentiate between exogenous (stimulus-dependent) and endogenous (non-stimulus-specific) neural activity. The aim of this study was to determine the spatiotemporal correlates of exogenous neural activity evoked by painful esophageal stimulation. METHODS In 16 healthy subjects (8 men; mean age, 30.2 +/- 2.2 years), we recorded magnetoencephalographic responses to 2 runs of 50 painful esophageal electrical stimuli originating from 8 brain subregions. Subsequently, 11 subjects (6 men; mean age, 31.2 +/- 1.8 years) had esophageal cortical evoked potentials recorded on a separate occasion by using similar experimental parameters. RESULTS Earliest cortical activity (P1) was recorded in parallel in the primary/secondary somatosensory cortex and posterior insula (approximately 85 ms). Significantly later activity was seen in the anterior insula (approximately 103 ms) and cingulate cortex (approximately 106 ms; P=.0001). There was no difference between the P1 latency for magnetoencephalography and cortical evoked potential (P=.16); however, neural activity recorded with cortical evoked potential was longer than with magnetoencephalography (P=.001). No sex differences were seen for psychophysical or neurophysiological measures. CONCLUSIONS This study shows that exogenous cortical neural activity evoked by experimental esophageal pain is processed simultaneously in somatosensory and posterior insula regions. Activity in the anterior insula and cingulate-brain regions that process the affective aspects of esophageal pain-occurs significantly later than in the somatosensory regions, and no sex differences were observed with this experimental paradigm. Cortical evoked potential reflects the summation of cortical activity from these brain regions and has sufficient temporal resolution to separate exogenous and endogenous neural activity.
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Affiliation(s)
- Anthony R Hobson
- Section of GI Science, Division of Medicine & Neurosciences-Hope, University of Manchester, Hope Hospital, Salford, Lancashire, UK.
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Rössel P, Arendt-Nielsen L, Niddam D, Chen ACN, Drewes AM. Short latency cerebral response evoked by painful electrical stimulation applied to the human sigmoid colon and to the convergent referred somatic pain area. Exp Brain Res 2003; 151:115-22. [PMID: 12712308 DOI: 10.1007/s00221-003-1484-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2002] [Accepted: 03/18/2003] [Indexed: 01/07/2023]
Abstract
Background. The brain-gut interaction is important for the understanding of pain mechanisms related to gastroenterological diseases. Unfortunately little is known about the early cerebral events related to the processing of gut-evoked pain. The aims of this human study were (1) to investigate the early-evoked brain potentials (EPs) to painful sigmoid colon stimulation and (2) to evaluate the EPs evoked from the convergent referred skin pain area after this area was induced by the painful gut stimulation. The background for the second aim was to evaluate whether the convergent input between somatic and visceral structures could induce detectable short-term cortical reorganization. Methods. Eleven subjects (nine men) participated; the mean age was 39.5+/-11.9 years. The gut-evoked EPs (recorded from 31 scalp sites) were evoked by electrical stimulation 30 cm from the anal verge by a modified biopsy forceps, inserted through a sigmoidoscope. The painful gut stimulation elicited a characteristic pain pattern referred to the abdomen. The short latency somatosensory evoked potentials were evoked from the skin inside and outside the referred pain area elicited by gut stimulation. A total of 750 electrical stimuli were delivered to the gut at slight painful stimulus intensity and 500 stimuli were delivered to the skin. Results. Short-latency EPs to electrical gut stimulation with an onset of 50-60 ms could be recorded. The gut EP topography revealed three consecutive positive peaks (P63, P101, P145) towards the frontal area. Centroparietal negativities (N128 and N222) were found, which were followed by two central positivities (P269 and P352). The somatic and gut evoked EPs differed in morphology and topography, but the EPs to skin stimulation inside and outside the gut-evoked referred pain area did not differ significantly. Conclusion. Short latency (50-60 ms) EPs to painful electrical sigmoid colon stimulation were demonstrated, reflecting an early cortical processing of sensory input from the sigmoid colon. The early cortical processing of somatic input from experimentally evoked visceral referred pain areas did not cause any detectable short-term cortical reorganization.
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Affiliation(s)
- Petra Rössel
- Laboratory for Visceral Pain and Biomechanics, Department of Medical Gastroenterology, Aalborg Hospital, 9000 Aalborg, Denmark
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Hobson AR, Aziz Q. Central nervous system processing of human visceral pain in health and disease. Physiology (Bethesda) 2003; 18:109-14. [PMID: 12750446 DOI: 10.1152/nips.01428.2002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To understand the pathophysiology of anomalous pain in functional gastrointestinal disorders, we must increase our understanding of how the central nervous system processes visceral pain. Over the past decade, novel application of functional brain imaging and electrophysiological techniques has given us the opportunity to study these processes in humans, and this review summarizes the current body of knowledge.
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Affiliation(s)
- Anthony R Hobson
- Section of Gastrointestinal Sciences, University of Manchester, Hope Hospital, Salford M6 8HD, United Kingdom
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Harris ML, Aziz Q. Brain-gut interaction in irritable bowel syndrome. HOSPITAL MEDICINE (LONDON, ENGLAND : 1998) 2003; 64:264-9. [PMID: 12789734 DOI: 10.12968/hosp.2003.64.5.1757] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Abdominal pain occurs commonly in irritable bowel syndrome. The mechanism of pain is likely to be either peripheral or central sensitization of gut nerves or aberrant brain processing. Functional brain techniques are now allowing the study of brain-gut interactions.
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Affiliation(s)
- M L Harris
- Department of Gastrointestinal Science, University of Manchester, Salford M6 8HD
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