Pudendal nerve stimulation for bowel dysfunction in complete cauda equina syndrome.

OBJECTIVE: Pudendal nerve stimulation (PNS) aims to maximize afferent or efferent stimulation from the sacral plexus. BACKGROUND: We hypothesized this may be a promising new treatment for patients with bowel dysfunction in complete cauda equina syndrome (CES). METHODS: Thirteen patients with complete CES [8 constipation predominant (group 1) and 5 incontinence predominant (group 2)] had a 3-week trial of PNS. Patients who showed a 50% or more improvement in symptoms during the trial phase proceeded to permanent neurostimulator implantation. RESULTS: Five (63%) of the 8 patients in group 1 showed a 50% or more improvement in bowel symptoms during the trial phase and were permanently implanted. The mean Cleveland Clinic constipation score, sense of incomplete evacuation (%), and straining during defecation (%) improved from 17 ± 3.2 to 10 ± 4.5, 94 ± 18% to 30 ± 35%, and 81 ± 23% to 44 ± 38%, respectively. All 5 patients in group 2 showed a 50% or more reduction in incontinent episodes during the trial phase. The mean St Mark's score, ability to defer defecation, and the number of incontinent episodes per week improved from 18 ± 1.0 to 3.8 ± 2.5, 2.2 ± 1.8 to 11 ± 5.5 minutes, and 9.4 ± 10.7 to 0.4 ± 0.5 episodes, respectively, per week. During a median follow-up of 12 (10-22) months of permanent implantation, one patient lost efficacy at 6 months due to lead migration and another required removal and reimplantation of the neurostimulator due to wound infection. CONCLUSIONS: PNS is an effective treatment in the short term for bowel dysfunction in some patients with complete CES.

Distinct neurophysiological profiles in irritable bowel syndrome.

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.