title: Anaesthesia Management for Awake Craniotomy: Systematic Review and Meta-Analysis.
abstract: BACKGROUND
  Awake craniotomy (AC) renders an expanded role in functional neurosurgery. Yet, evidence for optimal anaesthesia management remains limited. We aimed to summarise the latest clinical evidence of AC anaesthesia management and explore the relationship of AC failures on the used anaesthesia techniques.
  
  
  METHODS
  Two authors performed independently a systematic search of English articles in PubMed and EMBASE database 1/2007-12/2015. Search included randomised controlled trials (RCTs), observational trials, and case reports (n>4 cases), which reported anaesthetic approach for AC and at least one of our pre-specified outcomes: intraoperative seizures, hypoxia, arterial hypertension, nausea and vomiting, neurological dysfunction, conversion into general anaesthesia and failure of AC. Random effects meta-analysis was used to estimate event rates for four outcomes. Relationship with anaesthesia technique was explored using logistic meta-regression, calculating the odds ratios (OR) and 95% confidence intervals [95%CI].
  
  
  RESULTS
  We have included forty-seven studies. Eighteen reported asleep-awake-asleep technique (SAS), twenty-seven monitored anaesthesia care (MAC), one reported both and one used the awake-awake-awake technique (AAA). Proportions of AC failures, intraoperative seizures, new neurological dysfunction and conversion into general anaesthesia (GA) were 2% [95%CI:1-3], 8% [95%CI:6-11], 17% [95%CI:12-23] and 2% [95%CI:2-3], respectively. Meta-regression of SAS and MAC technique did not reveal any relevant differences between outcomes explained by the technique, except for conversion into GA. Estimated OR comparing SAS to MAC for AC failures was 0.98 [95%CI:0.36-2.69], 1.01 [95%CI:0.52-1.88] for seizures, 1.66 [95%CI:1.35-3.70] for new neurological dysfunction and 2.17 [95%CI:1.22-3.85] for conversion into GA. The latter result has to be interpreted cautiously. It is based on one retrospective high-risk of bias study and significance was abolished in a sensitivity analysis of only prospectively conducted studies.
  
  
  CONCLUSIONS
  SAS and MAC techniques were feasible and safe, whereas data for AAA technique are limited. Large RCTs are required to prove superiority of one anaesthetic regime for AC.
authors.affiliation: Department of Anaesthesiology, University Hospital RWTH Aachen, Aachen, Germany.
authors.forename: Ana
authors.identifier: http://orcid.org/0000-0002-7433-8675
authors.initials: A
authors.lastname: Stevanovic
authors.affiliation: Department of Anaesthesiology, University Hospital RWTH Aachen, Aachen, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Rossaint
authors.affiliation: Department of Anaesthesiology, University Hospital RWTH Aachen, Aachen, Germany.|Department of Neurosurgery, University Hospital RWTH Aachen, Aachen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Veldeman
authors.affiliation: Department of Anaesthesiology, Critical Care and Pain Medicine, University of Rome "La Sapienza", Rome, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Bilotta
authors.affiliation: Department of Anaesthesiology, University Hospital RWTH Aachen, Aachen, Germany.
authors.forename: Mark
authors.initials: M
authors.lastname: Coburn
mesh_terms: D000758:Anesthesia / Q000009:adverse effects / Q000379:methods*; D003399:Craniotomy / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D014851:Wakefulness