Neurologic Changes During Awakening from Anesthesia

Abstract

Transient hyperreflexia, the Babinski reflex and other transient neurologic signs may follow anesthesia in healthy persons. The appearances and durations of these signs were described and related to anesthetic agent, time following cessation of anesthesia and state of arousal. Neurologically normal male patients (29) undergoing superficial operations were anesthetized with halothane-N2O, enflurane-N2O, or N2O-narcotic. During awakening, patients experienced transient hyperreflexia and shivering following all anesthetic techniques. Quadriceps hyperreflexia occurred in 3 of 8 patients after halothane-N2O, 7 of 12 patients after enflurane-N2O and no patient after N2O-narcotic anesthesia. Sustained ankle clonus and upgoing plantar responses were observed most frequently following enflurane-N2O (50% of patients). Following halothane-N2O, ankle clonus was observed in 12.5% of patients and upgoing plantar responses in 25% of patients. Neither sign occurred after N2O-narcotic anesthesia. Shivering, too, was observed most frequently after enflurane anesthesia (66% of patients). There were equal reductions of body temperature in shivering and nonshivering patients. In every patient, regardless of the anesthetic used, the lash reflex and the pupillary response to light returned to normal with the return of consciousness as measured by the response to verbal commands. The neurologic profile during awakening from general anesthesia is most abnormal following enflurane N2O, compared with halothane-N2O and N2O-narcotic anesthesia. Abnormalities are found most frequently when patients are poorly responsive to verbal commands. Their incidence diminishes with time but abnormal responses to neurologic examination may persist for 40 min or more after cessation of anesthesia.