Sudden asystole during craniotomy: unrecognized phenytoin toxicity.

The authors report a case of intraoperative sinus arrest in an otherwise healthy patient undergoing craniotomy for aneurysm clipping after mild subarachnoid hemorrhage. The sinus arrest was precipitated by a rapid infusion of 1500 mg phenytoin and was successfully treated with standard resuscitative measures. The differential diagnosis of intraoperative cardiac arrest and the mechanisms of action of phenytoin are discussed. The authors emphasize the role of phenytoin in cerebral protection.