Correlation of pudendal nerve terminal motor latency with the results of anal manometry

Denervation to the external anal sphincter is commonly found in disordered defaecation. Aim: To determine whether a correlation exists between pudendal nerve terminal motor latency (PNTML) and anal manometry and what influence an external sphincter defect (ESD) has on any correlation. Method: Sixty seven consecutive patients (23 constipated, 44 incontinent) were analysed. All had results available for PNTML and anal manometry. Anal ultrasound performed in the later part of the study period was available in 46 patients. Results: A significant negative correlation was found between the mean PNTML and squeeze pressures (SP) for incontinent patients (r = -0.32, P = 0.037). No significant correlation was seen in constipated patients. A coexisting ESD was found in 57% of the 46 patients studied. In those without an ESD a significant negative correlation was found between mean PNTML and SP (r = -0.50; P = 0.026). No correlation was found in patients with an ESD. Age did not significantly affect the PNTML or SP results, but was associated with a reduced resting pressure (r = -0.34; P = 0.005). Conclusions: The PNTML was significantly correlated with SP in patients with incontinence and in the subgroup of patients without an ESD. In the assessment of disordered defaecation PNTML is therefore recommended as an adjunct to anal ultrasound.