Do patients with haemorrhoids have pelvic floor denervation?

Straining at stool is found in patients with haemorrhoids, rectal prolapse and neurogenic (idiopathic) faecal incontinence. In the latter two conditions perineal descent and pudendal neuropathy occur. We have carried out anal manometry, measurement of perineal descent, pudendal nerve terminal motor latency (PNTML) and single fibre EMG in the external anal sphincter in 16 patients with haemorrhoids and 20 matched control subjects to determine whether patients with haemorrhoids have pudendal nerve damage. There was no significant difference in resting or voluntary contraction pressures or in the incidence of slow waves or ultra-slow waves between the patients with haemorrhoids and controls. There was a significant difference between the groups in the position of the perineum with respect to the ischial tuberosities at rest (p less than 0.025) and on defaecation straining (p less than 0.005). The mean PNTML was higher in the haemorrhoid group but this did not reach statistical significance (p = 0.07). The mean fibre density was significantly higher in the haemorrhoid group (p less than 0.025). These findings show that patients with haemorrhoids are more likely to have abnormal perineal descent with pudendal neuropathy.