Neurocognitive outcomes in adults following cerebral hypoxia: A systematic literature review

BACKGROUND: Hypoxic ischemic brain injury (HIBI) occurs as a result of complete or partial disruption of cerebral oxygen supply. The physical and cognitive sequelae of adults following hypoxia varies widely.

OBJECTIVE: To systematically review studies exploring the neuropsychological outcomes following hypoxic brain insult in adults.

METHODS: Data was sourced using six databases (CINAHL, Cochrane, Embase, Medline, PsycInfo and Web of Science). Initial MESH terms identified 2,962 articles. After a three-stage independent review process, 18 articles, 9 case studies and 9 group studies were available for data synthesis from 1990-2012. Case study data was converted to standardised scores and compared to available test norms. Cohen's d was calculated to permit group data interpretation.

RESULTS: Intellectual decrement was observed in some studies although difficult to delineate given the lack of use of measures of premorbid ability. Cognitive sequelae varied albeit with predominant disturbance in verbal memory, learning ability and executive function observed across studies. Wechsler Memory Scale Revised (WMS-R) visual memory was comparable to normative data. Impaired Rey Osterrieth Complex Figure (ROCFT) performance was found among group studies. Across visuo-constructional and attention domains, performance varied, although no significant difference relative to reported means was observed.

CONCLUSIONS: Future studies should consider the use of standardised assessment protocols, which include measures of premorbid functioning and performance validity.