Electrically evoked activity in the XXXX external anal sphincter.

@entity1 @entity4094 @entity16 @entity322
Following electrical stimulation of perianal skin, short latency evoked electromyographic (EMG) responses from the external and sphincter have been interpreted as the electrophysiological correlate of the anal reflex. Delayed responses in @entity1 with idiopathic @entity322 have been interpreted as evidence for denervation of the external anal sphincter. Electrically evoked responses were studied in normal subjects, either before and during spinal anaesthesia (n = 8), or before and during competitive @entity4094 (n = 4), instituted for operative purposes. Short latency responses persisted unchanged in either latency or duration during spinal anaesthesia whereas long latency responses were completely abolished. Both short and long latency responses were abolished during competitive @entity4094 . Short latency responses are not spinal reflex in nature, but due to stimulus activation of alpha-motoneuronal terminal branches. Delayed responses in incontinent @entity1 cannot be interpreted as evidence for @entity16 . Long latency (i.e. greater than 40 ms) responses demand a functional sacral spinal cord and represent the true anal reflex. Their wide range of latency in normal subjects suggests this measurement will be of little use in confirming the presence or absence of @entity16 , and that other measures of @entity16 may be more appropriate.
