The Inhibitory Effects of Pudendal Nerve Stimulation on Bladder Overactivity in Spinal Cord Injury Dogs: Is Early Stimulation Necessary?

Vaginal Lubrication and Pressure Increase Induced by Pudendal Nerve Stimulation in Cats

BACKGROUND

Vaginal lubrication and contractions are among the top difficulties affecting sexual intercourse in women after spinal cord injury.

AIM

This study aimed at determining if pudendal nerve stimulation (PNS) can improve vaginal lubrication and induce increases in vaginal pressure.

METHODS

In anesthetized cats, a small piece of cotton was inserted into the vagina for 10 minutes with or without PNS to measure vaginal wetness by the weight increase of the vaginal cotton. Then, a small balloon catheter was inserted into the vagina to measure the pressure increase induced by PNS. Intensity response of the vagina to PNS (30 Hz, 0.2 ms, 5 seconds) was determined at 1-4 times of intensity threshold (T) for PNS to induce an observable vaginal pressure increase. Frequency response was determined at 2T intensity in a range of PNS frequencies (5-50 Hz). Finally, fatigue in vaginal pressure was determined by applying PNS (30 Hz, 2T) either continuously or intermittently (5 seconds on and 5 seconds off) for 4 minutes.

OUTCOMES

The effectiveness of PNS in increasing vaginal wetness and pressure is evaluated.

RESULTS

PNS significantly (P = .0327) increased the measurement of vaginal wetness from 15.8 ± 3.8 mg during control without stimulation to 32.4 ± 4.7 mg after stimulation. Vaginal pressure increased as PNS intensity or frequency increased. PNS (30 Hz, 2T) induced vaginal pressure increase ≥80% of the maximal response. Intermittent PNS induced significantly (P = .0354) smaller fatigue (45.6 ± 3.7%) in vaginal pressure than continuous PNS (69.1 ± 3.0%) during the 4-minute stimulation.

CLINICAL TRANSLATION

This study raises the possibility of developing a novel pudendal neuromodulation device to improve female sexual function after spinal cord injury.

STRENGTHS & LIMITATIONS

This study provides preclinical data supporting the development of a novel pudendal neuromodulation device. The limitation includes the lack of chemical analysis of the vaginal secretion.

CONCLUSION

PNS can improve vaginal lubrication and induce increases in vaginal pressure.

Early sacral neuromodulation ameliorates urinary bladder function and structure in complete spinal cord injury minipigs

Aims

To determine the effects of early sacral neuromodulation (SNM) and pudendal neuromodulation (PNM) on lower urinary tract (LUT) function, minipigs with complete spinal cord injury (cSCI) were analyzed. SNM and PNM have been proposed as therapeutic approaches to improve bladder function, for example after cSCI. However, further evidence on efficacy is required before these methods can become clinical practice.

Methods

Eleven adults, female Göttingen minipigs with cSCI at vertebral level T11‐T12 were included: SNM (n = 4), PNM (n = 4), and SCI control (SCIC: n = 3). Tissue from six healthy minipigs was used for structural comparisons. Stimulation was started 1 week after cSCI. Awake urodynamics was performed on a weekly basis. After 16 weeks follow‐up, samples from the urinary bladder were taken for analyses.

Results

SNM improved bladder function with better capacities and lower detrusor pressures at voiding and avoided the emergence of detrusor sphincter dyssynergia (DSD). PNM and untreated SCI minipigs had less favorable outcomes with either DSD or constant urinary retention. Structural results revealed SCI‐typical fibrotic alterations in all cSCI minipigs. However, SNM showed a better‐balanced distribution of smooth muscle to connective tissue with a trend towards the reduced progression of bladder wall scarring.

Conclusion

Early SNM led to an avoidance of the emergence of DSD showing a more physiological bladder function during a 4 month follow‐up period after cSCI. This study might pave the way for the clinical continuation of early SNM for the treatment of neurogenic LUT dysfunction after SCI.

Estimation of Bladder Pressure and Volume from the Neural Activity of Lumbosacral Dorsal Horn Using a Long-Short-Term-Memory-based Deep Neural Network

In this paper, we propose a deep recurrent neural network (DRNN) for the estimation of bladder pressure and volume from neural activity recorded directly from spinal cord gray matter neurons. The model was based on the Long Short-Term Memory (LSTM) architecture, which has emerged as a general and effective model for capturing long-term temporal dependencies with good generalization performance. In this way, training the network with the data recorded from one rat could lead to estimating the bladder status of different rats. We combined modeling of spiking and local field potential (LFP) activity into a unified framework to estimate the pressure and volume of the bladder. Moreover, we investigated the effect of two-electrode recording on decoding performance. The results show that the two-electrode recordings significantly improve the decoding performance compared to single-electrode recordings. The proposed framework could estimate bladder pressure and volume with an average normalized root-mean-squared (NRMS) error of 14.9 ± 4.8% and 19.7 ± 4.7% and a correlation coefficient (CC) of 83.2 ± 3.2% and 74.2 ± 6.2%, respectively. This work represents a promising approach to the real-time estimation of bladder pressure/volume in the closed-loop control of bladder function using functional electrical stimulation.

Neurophysiologic study in idiopathic overactive bladder

AIM

Idiopathic overactive bladder (OAB) is a prevalent, mystifying disorder with a questionable neurogenic background. We aimed to investigate the possible subtle neuropathic affection underlying its pathogenesis.

METHODS

A cross-sectional cut off study was carried out on a series of 38 females with idiopathic OAB and 22 healthy matched female volunteers. The following was performed: symptom score questionnaire, determination of pudendal nerve terminal motor latency (PNTML), sacral reflexes' latencies, pudendal somatosensory evoked potentials, and needle electromyography of the external anal and urethral sphincters.

RESULTS

A highly significant prolongation of PNTMLs and sacral reflexes latencies among the patients group was detected (P ≥ 0.001). Pudendal somatosensory evoked potentials showed non- significance among the two studied groups (P ≥ 0.05). External anal sphincter neuropathic affection was detected in 27 patients (71%) and external urethral sphincter neuropathic affection was detected in 30 patients (78.9%). The clitoral anal reflex showed the highest sensitivity and specificity among the neurophysiologic tests used in assessing the neuropathic affection (86.7 and 83%, respectively), followed by PNTML (83.3 and 80%, respectively).

CONCLUSION

Pudendal neuropathy is the dominating possible attributing factor in the pathogenesis underlying idiopathic OAB. An integrated clinical, urodynamic, and electro-physiological assessment is recommended for evaluation of any overactive bladder patients.

Increasing bladder capacity by foot stimulation in rats with spinal cord injuries

Background

This study was to explore the possibility that foot stimulation increased bladder capacity(BC) in rats with neurogenic bladder secondary to T10 spinal cord injuries.

Methods

In 20 awake rats (stimulation group) with T10 spinal cord injuries, 5 repeat cystometrograms (CMGs) were recorded. The 1st and 2nd CMGs were performed without stimulation. The 3rd, 4th, and 5th CMGs were done separately with 1 T, 2 T, and 4 T stimulation, respectively, through a pair of pad electrodes on the skin of the hind foot. In the control group of 20 rats, 5 repeat CMGs were recorded without foot stimulation. The threshold (T) was the minimal stimulation intensity to induce an observable toe twitch.

Results

In the stimulation group, foot stimulation with 2 T significantly increased the BC an additional 68.9% ± 20.82% (p < 0.05). Foot stimulation with 4 T increased the BC an additional 120.9% ± 24.82% (p < 0.05). Compared with the control group, BC in the 1st, 2nd, and 3rd (1 T) CMG had no significant difference in the stimulation group, but the 4th (2 T) and 5th (4 T) CMGs were significantly increased (p < 0.05).

Conclusions

Electrical stimulation of the foot was effective in inhibiting reflex bladder activity and increasing bladder capacity in spinal cord injury rats.

Can intraurethral stimulation inhibit micturition reflex in normal female rats?

Objective

The study was designed to determine the effect of low frequency (2.5Hz) intraurethral electrical stimulation on bladder capacity and maximum voiding pressures.

Materials and Methods

The experiments were conducted in 15 virgin female Sprague-Dawley rats (220–250g). The animals were anesthetized by intraperitoneal injection of urethane (1.5g/kg). Animal care and experimental procedures were reviewed and approved by the Institutional Animal Care and Use Committee of Antwerp University (code: 2013-50). Unipolar square pulses of 0.06mA were used to stimulate urethra at frequency of 2.5Hz (0.2ms pulse width) in order to evaluate the ability of intraurethral stimulation to inhibit bladder contractions. Continuous stimulation and intermittent stimulation with 5sec ‘‘on’’ and 5sec ‘‘off’’ duty cycle were applied during repeated saline cystometrograms (CMGs). Maximum voiding pressures (MVP) and bladder capacity were investigated to determine the inhibitory effect on bladder contraction induced by intraurethral stimulation.

Results

The continuous stimulation and intermittent stimulation significantly (p<0.05) decreased MVP and increased bladder capacity. There was no significant difference in MVP and bladder capacity between continuous and intermittent stimulation group.

Conclusions

The present results suggest that 2.5Hz continuous and intermittent intraurethral stimulation can inhibit micturition reflex, decrease MVP and increase bladder capacity. There was no significant difference in MVP and bladder capacity between continuous and intermittent stimulation group.

Structural Changes of the Urinary Bladder After Chronic Complete Spinal Cord Injury in Minipigs

Purpose

The aim of this study was to determine the structural changes of the urinary bladder after chronic spinal cord injury (SCI) in minipigs with the primary focus on the analysis of urinary bladder wall proteins and their quantitative distribution.

Methods

Seven Göttingen minipigs (adult, female) underwent a complete spinal cord transection. Follow-up time was 4 months during which the bladder was drained by frequent single catheterisation and data from the bladder diary and daily urine strip test were collected. Samples from the urinary bladder were taken, fixed in 4% paraformaldehyde and stained for histological analyses. Bladder wall thickness, single tissue quantities/distributions, types I and III collagen, and elastin quantifications were performed. Comparisons to healthy urinary bladder tissue of age-matched minipigs were performed for statistical analyses.

Results

No urinary tract infections were observed in our SCI minipig collective during follow-up. A trend towards a reduction in bladder volumes and an increase in incontinence periods were seen. The bladder wall thickness significantly increased after chronic SCI. Furthermore, bladder wall composition was severely altered by a significant loss of smooth muscle tissue and a significant increase in connective tissue. Elastic fibres were reduced in number and altered in their structural appearance after SCI. Type I collagen was significantly increased, while type III collagen was significantly decreased after SCI.

Conclusions

Chronic SCI highlighted that the urinary bladder wall undergoes fibrotic events with reduced contractile and elastic properties due to changes of the bladder wall protein composition. These changes show in detail how SCI severely influences the urinary bladder wall composition and depicts the similarities between minipigs and humans.

Evaluation and Management of Neurogenic Bladder: What Is New in China?

Neurogenic bladder (NB) or neurogenic lower urinary tract dysfunction (NLUTD), a dysfunction of the urinary bladder and urethra due to disease of the central nervous system or peripheral nerves, is a major global medical and social problem. Numerous nervous system abnormalities, such as: stroke, Alzheimer's and Parkinson's diseases, traumatic spinal cord injury, spinal cord tumors, congenital spina bifida, and diabetes, can cause NB/NLUTD. There are two major types of bladder control problems associated with NB/NLUTD: the bladder becomes either overactive or underactive depending on the nature, level, and extent of nerve damage. This review specifically focuses on the diagnosis and management of NB/NLUTD in China as well as on recent efforts to treat this disease.

Neuromodulation for Neurogenic Bladder

Although neuromodulation is well established for the treatment of non-neurogenic lower urinary tract symptoms, recent literature supports its use in the patient having LUTS associated with a neurologic condition. Sacral neuromodulation, in particular, may see new use as a modality to facilitate neurologic remodeling in spinal cord injured patients as well as children. As a therapeutic option, sacral neuromodulation and dorsal genital nerve stimulation may one day become more effective and more efficient utilizing the concept of closed-loop feedback, where electro-neurogram and bladder pressure data are incorporated into stimulation routines. In addition, some older therapies are reviewed that have recently demonstrated success in this patient population.