[Numbness of the lower lip following general anesthesia]

Injuries to nerves of the head occur infrequently following general anesthesia. Lesions of the facial and mental nerves have been reported.

A healthy 40-year-old woman was scheduled for derotation osteotomy of the left femur. The previous medical history included ten uneventful general anesthetics mainly for abdominal and orthopedic surgery. Routine preoperative investigations were unremarkable. The patient received midazolam for premedication. Induction of anesthesia was carried out with thiopental and succinylcholine. Ventilation with the anesthesia mask was difficult, and considerable pressure was exerted on the mask. Intubation of the trachea was accomplished on the second attempt after additional doses of thiopental and succinylcholine and intermittent manual ventilation by mask, which lasted for 5-6 min. The further course of anesthesia was uneventful. The surgical procedure lasted for 1 1/2 h. On the 1st day after anesthesia the patient noticed numbness of the lower lip. Perception of temperature and touch was impaired. The area of paresthesia/anesthesia corresponded to the area of innervation of the upper branches of the mental nerves. Complete remission occurred within 6 weeks.

Injury to nerves of the head due to pressure applied during anesthesia is infrequent. Lesions of branches of the facial nerve--mainly the marginal mandibular branch--have been reported. We found only two case reports of injury to the mental nerve in the literature. In general, long lasting anesthesia delivered via face mask preceded the injury. It was frequently difficult to retain airway patency.(ABSTRACT TRUNCATED AT 250 WORDS)