Awake Craniotomy Induces Fewer Changes in the Plasma Amino Acid Profile Than Craniotomy Under General AnesthesiaHol, Jaap W. MD*; Klimek, Markus MD*; van der Heide-Mulder, Marieke BSc†; Stronks, Dirk PhD*; Vincent, Arnoud J. MD, PhD‡; Klein, Jan MD, PhD*; Zijlstra, Freek J. PhD*; Fekkes, Durk PhD†Journal of Neurosurgical Anesthesiology: April 2009 - Volume 21 - Issue 2 - p 98-107 doi: 10.1097/ANA.0b013e318192d4aa Clinical Investigations Abstract Author Information In this prospective, observational, 2-armed study, we compared the plasma amino acid profiles of patients undergoing awake craniotomy to those undergoing craniotomy under general anesthesia. Both experimental groups were also compared with a healthy, age-matched and sex-matched reference group not undergoing surgery. It is our intention to investigate whether plasma amino acid levels provide information about physical and emotional stress, as well as pain during awake craniotomy versus craniotomy under general anesthesia. Both experimental groups received preoperative, perioperative, and postoperative dexamethasone. The plasma levels of 20 amino acids were determined preoperative, perioperative, and postoperatively in all groups and were correlated with subjective markers for pain, stress, and anxiety. In both craniotomy groups, preoperative levels of tryptophan and valine were significantly decreased whereas glutamate, alanine, and arginine were significantly increased relative to the reference group. Throughout time, tryptophan levels were significantly lower in the general anesthesia group versus the awake craniotomy group. The general anesthesia group had a significantly higher phenylalanine/tyrosine ratio, which may suggest higher oxidative stress, than the awake group throughout time. Between experimental groups, a significant increase in large neutral amino acids was found postoperatively in awake craniotomy patients, pain was also less and recovery was faster. A significant difference in mean hospitalization time was also found, with awake craniotomy patients leaving after 4.53±2.12 days and general anesthesia patients after 6.17±1.62 days; P=0.012. This study demonstrates that awake craniotomy is likely to be physically and emotionally less stressful than general anesthesia and that amino acid profiling holds promise for monitoring postoperative pain and recovery. Departments of *Anesthesiology †Neuroscience and Psychiatry ‡Neurosurgery, Erasmus MC, Rotterdam, The Netherlands The HPLC analysis was funded by a departmental research budget. Reprints: Freek J. Zijlstra, PhD, Department of Anesthesiology, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands (e-mail: firstname.lastname@example.org). Received for publication June 2 2008; accepted October 27 2008 The authors report no conflicts of interest. © 2009 Lippincott Williams & Wilkins, Inc.