Effect of Cranial Surgery and Brain Tumor Size on Emergence from Anesthesia

Abstract

Background Knowing which neurosurgical patients are at risk for delayed awakening may lead to better utilization of intensive care resources and avoid the risk and cost of pharmacologic reversal and diagnostic tests. Methods The authors compared anesthetic emergence from complex spinal surgery (spine; n = 47) with that from craniotomy for supratentorial nonfrontal (n = 22), frontal (n = 34), or posterior fossa tumor (n = 28). A further comparison involved patients with small versus large (diameter > 30 mm, mass effect) tumors. The standardized anesthetic regimen consisted of induction with 2-4 mg/kg-1 thiopental and 1-2 micrograms/kg-1 sufentanil, followed by maintenance with nitrous oxide, 0.2-0.5 micrograms.kg-1.h-1 sufentanil and < or = 0.5% isoflurane. Sufentanil administration was terminated on dural or spinal muscle closure, isoflurane during skin closure, and nitrous oxide during dressing application. After discontinuing nitrous oxide, a minineurologic examination was performed every 15 min for 1 h, then hourly for 4 h and at 24 h. Results Craniotomy patients performed less well than spinal surgery patients on the minineurologic examination 15 and 30 min after discontinuing nitrous oxide. At 15 min, fewer patients with large (vs. small) tumors were oriented to time (58% vs. 87%; P < 0.01) or place (67% vs. 90%; P < 0.01). Forty-two percent of patients with large tumors still had an abnormal minineurologic examination score versus 15% of patients with small tumors. At 30 min, these values were 28% and 8%, respectively (P < 0.05). Seventy-one percent of patients with large tumors were oriented to time compared to 97% for small lesions (P < 0.01). Emergence from anesthesia was similar for spinal surgery patients and patients with small brain tumors. Conclusion Patients undergoing craniotomy for large intracranial mass lesions awaken more slowly than patients after spinal surgery or craniotomy for small brain tumor.