Anal sphincter motor unit potential (MUP) differences between sides, between rest and voluntary contraction, and between MUP analysis programs in normal subjects.

Trauma to the external anal sphincter resulting in incontinence is a relatively common disorder. Methods to detect damage include pudendal nerve conduction studies and needle EMG. We have applied a quantitative EMG technique using decomposition-enhanced software to isolate motor unit potentials (MUPs) and their surface representation from an anal probe electrode in healthy nulliparous women. MUPs were readily isolated and metric values compared favorably with those recorded with different software.