title: Effects of intraoperative hypothermia on neuropsychological outcomes after intracranial aneurysm surgery.
abstract: OBJECTIVE
  Subarachnoid hemorrhage and surgical obliteration of ruptured intracranial aneurysms are frequently associated with neurological and neuropsychological abnormalities. We reported that intraoperative cooling did not improve neurological outcome in good-grade surgical subarachnoid hemorrhage patients, as assessed by the Glasgow Outcome Scale score or other neurological and functional measures (National Institutes of Health Stroke Scale, Rankin Disability Scale, Barthel Activities of Daily Living). We now report the results of neuropsychological testing in these patients.
  
  
  METHODS
  A total of 1,001 patients who bled < or = 14 days before surgery were randomly assigned to intraoperative hypothermia (t = 33 degrees C) or normothermia (37 degrees C). Outcome was assessed approximately 3 months after surgery. Patients underwent the Benton Visual Retention, Controlled Oral Word Association, Rey-Osterrieth Complex Figure, Grooved Pegboard, and the Trail Making tests. T-scores for each test were calculated from normative data. T-scores were averaged to calculate a Composite Score. A test result (or the Composite Score) was considered "impaired" if the T-score was two or more standard deviations below the norm. A Mini-Mental State Examination was also performed.
  
  
  RESULTS
  Neurological outcome data were available in 1,000 patients. Sixty-one patients died. Of the 939 survivors, 873 completed 3 or more tests (exclusive of the Mini-Mental State Examination). Patients with poor neurological outcomes were less likely to complete testing; only 3.9% of Good Outcome (Glasgow Outcome Scale score = 1) patients were untested, compared with 38.6% of patients with Glasgow Outcome Scale scores of 3 and 4. There were no prerandomization demographic differences between the two treatment groups. For hypothermic patients, 16.8% were impaired from their Composite Score versus 20.0% of patients in the normothermic group (p = 0.317). For patients in the hypothermic group, 54.5% were impaired on at least one test, compared with 55.5% of patients in the normothermic group (p = 0.865). Similar results were seen in patients with baseline WFNS scores = I. Mini-Mental State Examination scores in the hypothermic and normothermic groups were 27.4 +/- 3.8 and 26.8 +/- 4.5, respectively.
  
  
  CONCLUSIONS
  This is the largest prospective evaluation of neuropsychological function after subarachnoid hemorrhage to date. Testing was completed in a high fraction of patients, demonstrating the feasibility of such testing in a large trial. However, the frequent inability to complete testing in poor-outcome patients suggests that testing may be best used to refine outcome assessments in good-grade patients. Many patients showed impairment on at least one test, with global impairment present in 17 to 20% of patients (18-21% of survivors). This was true even among the patients with the best preoperative condition (WFNS = 1). There was no difference in the incidence of impairment between hypothermic and normothermic groups.
authors.affiliation: Department of Neurology, University of Iowa Carver College of Medicine, Iowa City, IA.
authors.forename: Steven W
authors.initials: SW
authors.lastname: Anderson
authors.affiliation: Department of Anesthesia, University of Iowa Carver College of Medicine, Iowa City, IA.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Todd
authors.affiliation: Department of Anesthesia, University of Iowa Carver College of Medicine, Iowa City, IA.
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: Hindman
authors.affiliation: Department of Biostatistics, University of Iowa College of Public Health, Iowa City, IA.
authors.forename: William R
authors.initials: WR
authors.lastname: Clarke
authors.affiliation: Department of Epidemiology, University of Iowa College of Public Health, Iowa City, IA.
authors.forename: James C
authors.initials: JC
authors.lastname: Torner
authors.affiliation: Department of Neurology, University of Iowa Carver College of Medicine, Iowa City, IA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Tranel
authors.affiliation: Department of Biostatistics, University of Iowa College of Public Health, Iowa City, IA.
authors.forename: Bongin
authors.initials: B
authors.lastname: Yoo
authors.affiliation: Department of Anesthesia, University of Iowa Carver College of Medicine, Iowa City, IA.
authors.forename: Julie
authors.initials: J
authors.lastname: Weeks
authors.affiliation: Department of Neurology, University of Iowa Carver College of Medicine, Iowa City, IA.
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Manzel
authors.affiliation: Department of Anesthesiology, University of Michigan College of Medicine, Ann Arbor, MI.
authors.forename: Satwant
authors.initials: S
authors.lastname: Samra
mesh_terms: D000368:Aged; D000465:Algorithms; D003072:Cognition Disorders / Q000175:diagnosis* / Q000453:epidemiology*; D004185:Disability Evaluation; D005260:Female; D015600:Glasgow Coma Scale; D006801:Humans; D007036:Hypothermia, Induced / Q000379:methods*; D002532:Intracranial Aneurysm / Q000453:epidemiology / Q000601:surgery*; D007430:Intraoperative Care; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011184:Postoperative Period; D015995:Prevalence; D011594:Psychometrics; D012720:Severity of Illness Index; D013345:Subarachnoid Hemorrhage / Q000453:epidemiology / Q000601:surgery; D016896:Treatment Outcome