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Description:
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The Glasgow Coma Scale (GCS ) and duration of posttraumatic amnesia (PTA ) are the most commonly used clinical instruments for determining severity and predicting outcome in closed head injury (CHI ) . Many investigations have attempted to determine the relationship between head injury severity and cognitive outcome , as measured by neuropsychological assessment performance , but found mixed results with respect to utility of prediction . The present study proposed that a major reason for these mixed results was other investigations' inclusion of individuals with conditions known to detrimentally affect neuropsychological test performance (i .e . , history of alcoholism , drug abuse , psychiatric history , or previous neurologic insult ) into their closed head injury sample . This investigation directly examined this hypothesis by adding an additional comparison group , a closed head injury -clean group (CHI -C ) , and comparing this groups' performance against a closed head injury not -clean group (CHI -NC ) . The effects of combining the CHI -C and CHI -NC groups into one closed head injury combined (CHI -Comb ) group , as previous studies have done , was also examined .
Fifty -one consecutive patients (N = 51 ) underwent neuropsychological assessment following brain injury . Participants were included if they had exited PTA , demonstrated uncompromised upper extremity use , displayed adequate verbal communication , and were judged capable of completing full Wechsler Adult Intelligence Scale -Revised (WAIS -R ) , Wechsler Memory Scale , Controlled Oral Word Association Test , Stroop , and Trail Making Tests .
Separating the CHI individuals into the CHI -C and CHI -NC groups , and use of a logarithmic transformation , resulted in better prediction from severity measures to post -injury cognitive performance than observed in previous investigations . Moreover , despite the increased power of adding the CHI -C and CHI -NC groups into one CHIComb group , this combination obscured findings as predicted . Duration of PTA was a more reliable injury severity predictor than the GCS . Combining both measures in a prediction equation did not improve prediction . This investigation did not find the unique effects of closed head injury above that of other brain insults . Although the CHI -C and CHI -NC groups did not significantly differ on PTA duration and GCS severity level , the use of a pre -morbid PIQ estimate showed the CHI -NC group to have a greater post -injury PIQ loss than the CHI -C group . Furthermore , the mean VIQ /PIQ discrepancy was significantly larger for the CHI -NC group as compared to the CHI -C group . In conclusion , these findings as well as others from this investigation were discussed in terms of cognitive reserve theory . |