A neurogenic factor in faecal incontinence in the elderly.

Idiopathic faecal incontinence in middle-aged people has been found to be commonly associated with neurogenic damage to the anal sphincter musculature. Because neurogenic atrophy of skeletal muscle is a common feature of ageing, we have investigated the possibility that faecal incontinence in elderly people might be due to age-related denervation of the anal sphincter musculature. The technique of single fibre electromyography was used to measure the motor unit fibre density in the external and sphincter muscle in ten patients aged 78 to 99 years. Those patients whose continence was impaired had a markedly increased fibre density. Our findings suggest that neurogenic damage to the anal sphincter musculature may so reduce its functional reserve in elderly people that incontinence occurs when other factors, such as looseness of stool or depression of cerebral function, co-exist.