Role of pudendal nerve terminal motor latency assessment in constipated patients

The importance of pudendal nerve terminal motor latency assessment for the evaluation of incontinence is well established. However, its role in constipated patients remains unclear.

The purpose of the present study was to assess the incidence of pudendal neuropathy in constipated patients and its correlation with others variables including age, sex, anal pressures, and anal electromyography.

From 1988 to 1993, 161 patients with chronic constipation underwent pudendal nerve terminal motor latency assessment, anal electromyography, and anal manometry. The overall incidence of pudendal neuropathy was 23.6 percent; females and males had a similar incidence (24 percent vs. 23 percent, respectively; P > 0.05). Patients over 70 years old had a significantly higher incidence of pudendal neuropathy than did patients under 70 years (37 percent vs. 12 percent, respectively; P < 0.01). Patients with paradoxical puborectalis contraction on anal electromyographic assessment had a higher incidence of bilateral neuropathy, paradoxical puborectalis contraction (+)23 percent vs. paradoxical puborectalis contraction (-)8 percent, P < 0.05. Patients with pudendal neuropathy also had a higher incidence of decreased motor units potential recruitment than did patients without pudendal neuropathy (31.5 percent vs. 17 percent, respectively; P > 0.05).

Pudendal nerve terminal motor latency assessment was able to detect unsuspected pudendal neuropathy in 24 percent of patients. This finding correlated with age and with the presence of paradoxical puborectalis contraction but not with manometric anal pressures, motor unit potentials recruitment, or the presence of polyphasia. However, the often espoused relationship between pudendal latency and external sphincter function could not be demonstrated.