[Alcock's canal syndrome and perineal neuralgia]

Fifteen cases of perineal neuralgia are reviewed, the lesion arising from a canal syndrome due to compression of the pudendal nerve in the ischiorectal fossa (Alcock's canal syndrome). The clinical characteristic of the pain syndrome was its postural nature with the existence of a true Tinel sign (increased pain on sitting). Diagnosis was confirmed in all cases by a perineal electrophysiological which showed peripheral neurogenic signs on examination of perineal muscles and an increase in sacral evoked potentials latencies (latency of bulbocavernous or clitorido-anal reflexes, cortical somesthetic evoked potential from pudendal nerve). Treatment was infiltration of cortisone derivatives into the pudendal nerve canal, under CT guidance because of the difficulty of infiltrating the pudendal nerve by an external perineal approach. Results were satisfactory in 9 of the 15 patients.