Sacral neuromodulation in functional urinary retention: an effective way to restore voiding.

OBJECTIVE: To determine the long-term efficacy and complications of sacral nerve stimulation as an alternative therapy for functional unobstructive urinary retention, often considered to be psychogenic and effectively treated by clean intermittent catheterization, but for which pelvic floor dysfunction has been recognized as a possible cause. PATIENTS AND METHODS: Twenty patients (17 women and three men, mean age 48 years) with idiopathic, unobstructive functional urinary retention and in whom other forms of therapy had failed, had a pulse generator implanted (Medtronic, Minneapolis, MN, USA) and a sacral nerve implant. Their mean duration of symptoms was 68 months; 13 patients had chronic pelvic and perineal pain associated with their obstructive voiding symptoms. All patients were managed with clean intermittent catheterization and pharmacological therapy (alpha-blockers) before the procedure. All patients had a percutaneous nerve evaluation before the permanent implant, which showed> 50% improvement in their symptoms. All patients were evaluated at 1, 6 12, 18 and 24 months, then yearly thereafter. The results were assessed both subjectively by patient's symptoms and objectively by checking the postvoid residual volume (PVR) and voided volume. RESULTS: Eighteen patients were able to void spontaneously with a mean increase in voided volume from 48 to 198 mL, and a significant decrease in PVR from 315 to 60 mL. Eighteen of the patients had a > or = 50% improvement in their symptoms and said they would recommend the therapy to a friend or relative. Complications occurred in six patients. CONCLUSION: Sacral nerve stimulation is an effective and durable new approach to functional urinary retention, with few associated complications. Test stimulation provides a valuable tool for selecting patients.

Change of vanilloid receptor 1 following neuromodulation in rats with spinal cord injury.

BACKGROUND: Neuromodulation has been used to treat voiding dysfunction caused by spinal cord injury (SCI). However, the underlying mechanism of this technique is not well understood. Recently, vanilloid receptor 1 (VR1) has been recognized as a capsaicin receptor and an agent for noxious stimuli. The purposes of this study were to evaluate whether development of bladder hyperreflexia after SCI involves VR1 upregulation and whether VR1 is involved in the process of neuromodulation. MATERIALS AND METHODS: Sprague-Dawley rats (n = 20) were divided into five groups: sham control (n = 4); 3 days after SCI (n = 4); 7 days after SCI (n = 4); 14 days after SCI (n = 4), and 14 days after SCI with neurostimulation (n = 4). Bilateral electrode wires were implanted into S1 dorsal foramina and electrical stimulation was performed 8 h/day for 2 weeks. Spinal segments of L6, S1, and dorsal root ganglia were removed and cut into sections. The intensity of VR1 staining was evaluated by image analysis. RESULTS: VR1-positive staining was confined to the superficial dorsal horn of the spinal cord. The staining was weak in the sham group (1/luminosity: 0.0050 +/- 0.0006), but the staining intensity was significantly increased in three SCI groups (3 days, 7 days, and 14 days) when compared with that in the sham group (P < 0.05). After neuromodulation, the staining intensity was reduced. CONCLUSIONS: VR1 expression in the spinal cord is up-regulated after SCI. Sacral nerve root stimulation can down-regulate the VR1 expression.

Neuromodulation reduces urinary frequency in rats with hydrochloric acid-induced cystitis.

OBJECTIVE: To evaluate the effect of sacral neuromodulation on interstitial cystitis (IC) and determine the underlying mechanism of neuromodulation in the treatment of IC. Materials and methods Twenty Sprague-Dawley rats (body weight 220-250 g) were randomly divided into four equal groups; normal controls, a sham treatment (IC induced by 0.4 mol/L HCl, + saline), a second sham treatment (HCl-induced IC + acetic acid) and a stimulated group (HCl-induced IC + acetic acid, with electrical stimulation). In the last group bilateral electrodes were implanted into the S1 dorsal foramina and electrical stimulation applied for 8 h/day for 3 weeks. Acetic acid was instilled into the bladder to induce c-fos expression. After 3 weeks the rats were perfused with 4% paraformaldehyde, spinal segments dissected out and an immunocytochemical method used to stain the segments for fos protein encoded byc-fos. RESULTS: The mean (SEM) micturition frequency (voids/17 h) in the sham groups increased from 10.8 (2.7) to 23.4 (3.4) 3 weeks after the intravesical instillation of HCl. The micturition frequency in the stimulated group, at 16.2 (2.7), was significantly less than in the sham group (P = 0.04) after electrical stimulation for 3 weeks. There was no significant difference in the mean (SEM) number of fos-positive neurones in the L6 spinal cord segment between the stimulated and the sham + acetic acid group, at 43.6 (9.4) and 35.8 (7.8) cells/section, respectively (P = 0.32). CONCLUSIONS: In rats with HCl-induced cystitis, electrical stimulation reduced the micturition frequency, but not by inhibiting afferent c-fibre activity.