[Intraoperative positional damage to the ulnar nerve in anatomic variants].

After laparotomy (for acute abdomen) a 53-year-old woman had signs of pressure damage to the right ulnar nerve at the elbow. On open inspection at surgery 3 1/2 months later the rather deep right ulnar sulcus was markedly narrowed by connective tissue and the ulnar nerve thinned out; an epi- and perifascicular neurolysis was performed. There was no evidence of abnormal mobility of the left ulnar nerve. Nerve function gradually improved. Subsequent expert opinion concluded that adequate protective measures had been taken at the time of laparotomy to avoid positional or pressure damage to the nerve if the anatomy had been normal. - An abnormal mobility of a right ulnar nerve (it could be dislocated at the elbow) was demonstrated in a 35-year-old woman whose right ulnar nerve had been found to be damaged after laparotomy. It is recommended that, in the rare case in which such increased mobility is known preoperatively, the arm should be placed in supination with the elbow extended and carefully padded.