New method for assessment of anal sensation in various anorectal disorders.

A new technique for quantifying anal sensation utilizing mucosal electrosensitivity is described and has been tested in 97 patients. Normal subjects (n = 20) have a sensory threshold varying from 2 to 7.3 mA being most acute in the region of the anal valves. Sensory awareness also extends into the upper anal canal. Patients with neuropathic incontinence (n = 17) have a sensory deficit (P less than 0.002) whilst patients with haemorrhoids (n = 28) have less sensitive mucosa displaced into the upper anal canal (P less than 0.0001). Patients with acute fissure-in-ano (n = 10) have lower thresholds of sensation at the site of the fissure and slow transit constipation patients (n = 22) have normal anal sensation. The technique is reproducible and should prove useful in the investigation of anorectal disorders.