[Intermittent electromechanical dissociation of the internal anal sphincter in idiopathic fecal incontinence].

Ten patients with median age of 51 years (range 24-75; 9 female) presenting idiopathic faecal incontinence and twelve normal subjects with median age of 34 years (range 25-71; 5 female) underwent fine wire anal sphincter electromyography and anal manometry. The results were analysed using non-parametric methods of statistical analysis. The median IAS EMG was 0.30 Hz (range 0.18-0.38), in incontinent and 0.48 Hz (range 0.31-0.55) in controls; p. < 0.01. Ambulatory resting pressures were a median of 66 cmH2O (range 49-83 cmH2O), for the incontinent and 82 cmH2O (range 66-120) for controls; p < 0.04. IAS EMG frequency correlated with resting anal pressures in both groups (p < 0.003). IAS EMG silence not attributable to electrode movement or to the recto-anal inhibitory reflex, lasting 0.5-4 minutes, occurred in all but two of the incontinent patients. No recruitment of the external sphincter or puborectalis muscle was noted during these episodes. Such electromechanical dissociation was not seen in the control group.