Neuropsychology of closed head injury: The role of injury severity, site of impact, and elapsed recovery time upon neuropsychological outcome

Archival neuropsychological evaluations of 155 adult closed head injured patients were reviewed. Neuropsychological outcome data pertaining to intellectual, memory, and emotional functioning were respectively assessed with the Wechsler Adult Intelligence Scale-Revised (WAIS-R), Wechsler Memory Scale-Revised (WMS-R) and Randt Memory Test (RMT), and the Minnesota Multiphasic Personality Inventory (MMPI). Subjects were analyzed on these four outcome measures after being categorized according to injury severity, posttraumatic recovery time interval, and site of injury impact to the head.Analyses indicated that on the WAIS-R, the Digit Symbol subtest alone was consistently sensitive to injury severity. On the WMS-R, only an IQ-memory discrepancy measure was sensitive to severity. Delayed Picture Recognition on the RMT accounted for most of the sensitivity of this measure to injury severity. Two MMPI scales, Hs and Hy, demonstrated significantly greater mean elevations in mild than severe head injured patients.Cross-sectional analysis by six-month intervals during the initial two years of recovery from closed head injury yielded no meaningful significant findings for intellectual, memory, and emotional outcome measures. No significant interactions between elapsed recovery time and injury severity were noted. However, nonsignificant patterns were suggestive that subjects with nonsevere head injury continued to demonstrate improved memory functioning through the end of the first year and beginning of the second year of recovery, while severely injured subjects recovered at a slower rate and demonstrated improvement well into the second year of recovery. Nonseverely injured subjects demonstrated an increasing pattern of emotional complaints during the first year of recovery. Subjects with severe head injury experienced peak levels of psychopathology early in the second year of recovery, before showing rapid improvement by the close of the second year.Analyses of injury impact sites to the head by caudality and laterality yielded findings that a left-sided impact resulted in lower group mean scores on all WAIS-R subtests but Digit Symbol. On no measures of memory or emotional functioning did significant laterality or caudality effects emerge. No significant interactions between injury impact site and injury severity were demonstrated