[Neural electrophysiological observations on the external anal sphincter in patients with anorectal malformation]

To explore the functional damage of the nerves controlling external anal sphincter in patients with congenital anorectal malformation and to design a new method for measuring the conductive time of sacral spinal center in the pudendo-anal reflex arc.

45 patients with anorectal malformation and 20 normal subjects were subjected to detect the latency for pudendo-anal reflex, spinal-anal response and evoked potential of caude equine simultaneously. The conduction time of afferent motor nerve, efferent sense nerve and sacral spinal center in the pudendo-anal reflex arc were quantitatively analyzed.

The normal latency for pudendo-anal reflex was 23.3 +/- 6.9 ms, for spinal-anal response was 4.6 +/- 1.9 ms, and for evoked potential of caude equine was 3.8 +/- 0.9 ms. The conduction time of sacral spinal center was 14.8 +/- 6.6 ms. In patients with anorectal malformation, the latencies were prolonged obviously, especially the conduction time of sacral spinal center. There was a significant negative correlation between the latency and clinical scores. The correlation coefficient for pudendo-anal reflex was -0.68, for spinal-anal response was -0.64, and for conduction time of sacral spinal center was -0.60.

The abnormality of nerves serving anal sphincters was one of the important causes for postoperative fecal incontinence. The neural lesions are specially serious in the sacral spinal center.