A. Rodriguez

Patient controlled versus automatic stimulation of pudendal nerve afferents to treat neurogenic detrusor overactivity.

PURPOSE We investigated whether patients with neurogenic detrusor overactivity can sense the onset of bladder contraction and in turn suppress the contraction by electrical stimulation of the dorsal penile-clitoral nerve. MATERIALS AND METHODS A total of 67 patients with different neurological disorders were recruited to undergo 3 filling cystometries. The first cystometry was done without stimulation. The second cystometry was performed with automatic controlled stimulation based on detrusor pressure. The third cystometry was done with patient controlled stimulation using a push button. RESULTS Four females and 13 males underwent all 3 fillings. Compared to cystometry 1 average bladder capacity for cystometries 2 and 3 was 60% higher. Compared to peak pressure for cystometry 1 average peak pressure during suppressed contractions for cystometries 2 and 3 was 49% and 26% lower, respectively. The average delay of the onset of stimulation during cystometry 3 with respect to cystometry 2 was 5.7 seconds. CONCLUSIONS The study shows that patient controlled genital nerve stimulation is as effective as automatic controlled stimulation to treat neurogenic detrusor overactivity. Thus, patient controlled stimulation is feasible in select patients, although patients must be trained in the technique.

Urethral Sphincter EMG as Event Detector for Neurogenic Detrusor Overactivity

The aim of this study was to investigate the feasibility of using external urethral sphincter electromyogram (EMG) (EUSEMG) to detect the onset of detrusor contractions in patients with both neurogenic detrusor overactivity (NDO) and detrusor sphincter dyssynergia (DSD). Detrusor pressure (Pdet) and EUSEMG was recorded in 23 neurogenic patients during slow artificial bladder filling. The time delay between the onset of EUSEMG detrusor contraction and the onset of activity was calculated together with the detrusor pressure increase related to this delay. Of 23 patients enrolled, 12 patients showed both NDO and DSD. Of these 12 patients, 10 had a strong correlation between detrusor pressure and EUSEMG . One patient in this group was excluded due to a storage pressure above 30 cmH2O . Two detection methods were applied on the remaining 9 patients. Method 1 was a root mean square (RMS)-integrator with simple thresholding. This approach had a good sensitivity but also a poor specificity (many false-positive detections). Detection method 2 included a kurtosis-based scaling function, which was multiplied to a similar RMS-integrator as used in method 1. Onset detection occurred before Pdet exceeded 18 cmH2O with both methods. However, method 1 resulted in 14.1plusmn12.8 false-positive detections during one bladder filling.Pdet at onset detection was on average 1.0plusmn1.1 cmH2O higher with detection method 2 but the number of false-positives was reduced by 95.8%. This paper demonstrates the feasibility of using EUSEMG to estimate the onset of a detrusor contraction in selected patients.

Effect of sacral anterior root stimulator on bowel dysfunction in patients with spinal cord injury.

PURPOSE: Bowel dysfunction is a problem in patients with spinal cord injury. The sacral anterior root stimulator has been used for neurogenic bladder and has been claimed to be useful for neurogenic bowel. The purposes of this study were to analyze the clinical response of bowel function to the sacral anterior root stimulator and to evaluate physiologic factors that could determine its efficacy. METHODS: Eighteen consecutive patients with spinal cord injury and an implanted sacral anterior root stimulator were evaluated. Clinical assessment, colonic transit time, and anorectal manometry were performed. Patients were evaluated before implantation of the sacral anterior root stimulator and clinically reevaluated after 12 months. RESULTS: Fewer patients required laxatives after implantation of the sacral anterior root stimulator. The mean number of methods used to evacuate was reduced from 2.1 to 1.5 (P < 0.05). Bowel movement frequency was higher (P < 0.05). Time devoted to defecation was reduced, although no statistical significance was achieved. Fecal incontinence did not change, but constipation was reduced (P < 0.05). Most patients reported being more satisfied with bowel function after implantation of the sacral anterior root stimulator. No correlation was found between objective and subjective responses to the sacral anterior root stimulator and manometric or colonic transit times before implantation. CONCLUSION: The sacral anterior root stimulator improves bowel function, and patient satisfaction with this treatment is high. Further studies are needed to evaluate the characteristics of stimulation parameters to achieve better results.

Intraoperative recording of ENG from human sacral nerve roots

Intraoperative recoding of electroneurograms (ENG) from the S3 extradural sacral nerve roots was performed in 2 SCI patients. The goal of this work was to study the relation between mechanical stimulation of the urinary bladder, rectum and skin and the resulting ENC-signals. These signals could be used to detect the onset of a bladder contraction. This concept could be used in an implantable neuroprostheses to treat detrusor hyperreflexia. The recorded human signals are consistent with data from animal studies. However, more human studies are needed.