Nerves at the ventral prostatic capsule contribute to erectile function: initial electrophysiological assessment in humans.

BACKGROUND: Recent microanatomical studies have identified a significant amount of nerve fibers along the ventral circumference of the prostate capsule and confirmed the concept of a periprostatic nerve network. However, functional investigations have not yet proved whether nerve fibers distributed on the prostate capsule, particularly those outside the neurovascular bundle (NVB), contribute to erection. OBJECTIVE: To confirm whether nerve fibers distributed on the prostate capsule contribute to erectile function, the present study was performed using electrophysiologic testing. DESIGN, SETTING, AND PARTICIPANTS: The circumference of the prostate capsule was electrically stimulated during radical retropubic prostatectomy (RRP) in 12 patients with clinically localized prostate cancer (PCa). We defined the ventromedian circumference of the prostate capsule as the 12 o'clock position and the posterolateral position of the typical NVB as the 5 o'clock position. Periprostatic nerve fibers at the 12, 1, 2, 3, 4, and 5 o'clock positions of the midprostate were stimulated using bipolar electrodes. MEASUREMENTS: Changes in pressure at the middle of the urethra were measured using an inserted balloon catheter to detect increases in cavernosal pressure. RESULTS AND LIMITATIONS: Although the study included only 12 patients, every stimulation at all positions between 1 and 5 o'clock evoked urethral pressure responses in all patients. Mean pressure response was most powerful for 5 o'clock stimulation and decreased with stimulated points further from the 5 o'clock position. CONCLUSIONS: We demonstrated that electrostimulation at not only the posterolateral but also the anterior and lateral circumference of the prostate capsule can increase cavernosal pressure. These findings indicate that the periprostatic nerve network contributes to erections.

Primary somatosensory evoked magnetic fields elicited by sacral surface electrical stimulation.

To explore the brain response to sacral surface therapeutic electrical stimulation (SSTES) for the treatment of refractory urinary incontinence and frequent micturition, evoked magnetic fields were measured in six healthy males. Electrical stimuli were applied between bilateral surface electrodes over the second through fourth posterior sacral foramens with intensity just below the pain threshold. Somatosensory evoked magnetic fields (SEFs) for the bilateral median (MN) and posterior tibial nerves (PTN) were also measured for the comparison. Sources of the early SEF peaks were superimposed on individual magnetic resonance images. The first peak latency for sacral stimuli, M30, occurred at 30.2+/-0.8 ms (mean+/-standard deviation, N=6), with shorter latency than those for PTN stimulus (39.3+/-1.4 ms, N=12) and longer latency than those for MN stimulus (21.0+/-0.9 ms, N=12). The second peak latency for sacral stimuli, M50, occurred at 47.2+/-2.9 ms (N=6). Both M30 and M50 peaks showed a single dipole pattern over the vertex in the isofield maps. The equivalent current dipoles of M30 and M50 were both estimated near the medial end of the central sulcus with approximately posterior current direction. These results suggest that the sacral M30 and M50 are responses from the primary somatosensory cortex. The relatively long time lag between the onset and peak of M30 suggests that SSTES directly affects both the cauda equina and cutaneous nerve of the sacral surface.

Effects and indications of sacral surface therapeutic electrical stimulation in refractory urinary incontinence.

OBJECTIVE: To describe the effects and indications of sacral surface therapeutic electrical stimulation (SS-TES) for refractory urinary incontinence. DESIGN: Evaluation before and after therapy. SETTING: On clinical site and at nursing home. SUBJECTS: Seven neurogenic bladder, five unstable bladder and six nocturia cases were investigated. Twelve were outpatients and six were residents. INTERVENTIONS: Surface electrodes were placed at the posterior sacral foramens of S2 and S4. Stimulation conditions were duration 0.3 ms, frequency 20 Hz and maximum intensity. The stimulation was continued for 15 min twice daily for over one month. MAIN OUTCOME MEASURES: Therapeutic effects were evaluated on the basis of voiding charts as subjective findings and urodynamic study as objective findings before and after therapy. RESULTS: Subjective findings showed incontinence frequency significantly decreased from 2.3 +/- 1.4 times/day before therapy to 1.3 +/- 2.0 times/day after therapy (p < 0.01); 55.5% of patients were improved or greatly improved. Objective findings showed that maximum vesical capacity (MVC) significantly increased from 208.2 +/- 94.5 ml before therapy to 282.1 +/- 66.8 ml (p < 0.001). Uninhibited contraction significantly decreased from 40.4 +/- 31.4 cmH2O before therapy to 25.7 +/- 23.9 cmH2O (p < 0.01); 44% of patients were improved or greatly improved. This therapy was effective in particular for cases whose MVC was small before applying SS-TES. CONCLUSION: SS-TES was effective in some patients with refractory urinary incontinence.

Ipsilateral seminal emission generated by electrostimulation of the lumbar sympathetic nerve during nerve sparing laparoscopic retroperitoneal lymph node dissection for testicular cancer.

PURPOSE: To confirm nerve preservation during laparoscopic retroperitoneal lymph node dissection we perform electrostimulation of the lumbar sympathetic nerves relevant to ejaculation. In recent cases we monitored seminal emission using endoscopy of the posterior urethra to observe the response to stimulation. MATERIALS AND METHODS: Six patients with testicular tumors underwent intraoperative stimulation of the lumbar sympathetic nerves during laparoscopic retroperitoneal lymph node dissection with a unilateral modified template. A long handled pair of bipolar electrodes was inserted through a laparoscopic port, and ipsilateral and contralateral lumbar sympathetic nerves were individually electrostimulated. Ipsilateral stimulation was performed at the preserved lumbar splanchnic nerves and contralateral stimulation was performed at the union of nerve fibers derived from the lumbar splanchnic nerve just above the superior hypogastric plexus. The side of generated seminal emission was monitored simultaneously by endoscopy of the posterior urethra. RESULTS: In all patients each electrostimulation generated unilateral seminal emission. Each stimulation of a lumbar splanchnic nerve, whether ipsilateral or contralateral, caused seminal emission only from the ejaculatory orifice of the stimulated side. CONCLUSIONS: Intraoperative electrostimulation of the lumbar sympathetic nerves generated only ipsilateral seminal emission. This suggests that some efferent sympathetic signals for emission might run ipsilaterally in humans.

Electrostimulation of sympathetic nerve fibers during nerve-sparing laparoscopic retroperitoneal lymph node dissection in testicular tumor.

A long-handled pair of electrodes with sufficient length to allow stimulation during laparoscopic retroperitoneal lymph node dissection (RPLND) was designed at our institute. We clinically utilized this electrode in the treatment of a 37-year-old patient with testicular tumor who underwent right orchidectomy and nerve-sparing laparoscopic RPLND. During laparoscopic RPLND, sympathetic nerve fibers relevant to ejaculation were electrically stimulated and changes in pressure at the bladder neck were observed. Nerve preservation was confirmed by increased pressure at the bladder neck and ejaculation immediately after the electrostimulation. The application of laparoscopic electrostimulation may become widespread, particularly since it meets the increasing demand for minimally invasive surgery.