Effects of intraoperative hypothermia on neuropsychological outcomes after intracranial aneurysm surgery

Abstract

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.

Cognitive and Functional Outcome After Aneurysmal Subarachnoid Hemorrhage

“…Different aspects of executive function thus appear to have different rates of impairment. Among studies conducted in the past 10 years, deficits in cognitive flexibility, as measured by the Wisconsin Card Sorting Task, were found in 8% to 44% of patients with aSAH, 12,13,[15][16][17]19 whereas deficits in inhibition, as measured by the Stroop task, were found in 17% to 56% of patients with aSAH. 13,15,16 A study by Manning and colleagues 43 highlights the need to address different aspects of executive function.…”

“…Consequently, the prevalence of executive dysfunction in aSAH survivors is very wide with estimates ranging from 3% to 76%. 10,[12][13][14][15][16][17][18][19]37 Interestingly, self-reported deficits in executive function do not appear to correlate with results from objective cognitive tests; Ravnik and colleagues 38 found that patients with aSAH reported attentional deficits most frequently, yet patients performed better on tests of attention than on tests of other cognitive domains. Discordance between self-reported cognitive deficits and results from objective cognitive tests has also been reported in other domains, like memory.…”

“…The prevalence of language impairment in aSAH survivors is highly variable, ranging from 0% to 76%. 10,[12][13][14][15][16][17][18][19] Older age, fewer years of education, and aneurysms in the anterior circulation are significant predictors of poorer language function after aSAH. 21 Language function improves significantly within the first 3 months after aSAH 27 and continues to improve until 18 months after aSAH.…”

Recovery of Cognitive Function After Surgery for Aneurysmal Subarachnoid Hemorrhage

“…To date, no published study has examined the effect of intraoperative neuroprotection strategies used during aneurysm surgery on longitudinal postoperative cognitive function. The IHAST study provided information about the impact of mild intraoperative hypothermia on cognitive performance 3 months after surgery, 5 and this investigation reports recovery beyond that time frame. Use of mild intraoperative hypothermia did not have a significant effect on either composite scores or change in composite scores over time up to 15 months postsurgery, nor did it affect the frequency of patients with impaired cognitive function at different time points.…”

“…4 IHAST also assessed neurocognitive function 3 months postsurgery with 5 standard neuropsychological tests, which also failed to demonstrate any effect of intraoperative hypothermia. 5 This provided, however, the opportunity to longitudinally evaluate longer-term patterns of neurocognitive behavior in the study population.…”