[Perineal pain]. 
The investigation of patients suffering from perineal pain when sitting led us to perform an anatomical study of the pudendal nerve.  We dissected 50 cadavers and found areas of conflict for the nerve fibers.  The nerve trunk can become entrapped at the level of the ischiatic spine, in the Alcock's canal and when it crosses the falciform process.  Considering the clinical and neurophysiological data, this type of chronic pain may arise from compression of the nerve between the sacro-tuberal and the sacro-spinal ligaments, and/or in the fascia of the internal obturator muscle.  Much like treatment of entrapment of the median nerve in the wrist, we decided to treat chronic perineal pain by nerve blocks, and later by surgery.  We describe here the clinical symptoms, the neurophysiological data, and the technique of the nerve blocks.  For patients with persistent pain, we propose a posterior surgical approach which has provided successful pain relief in two third of patients.