[Intelligence and prognosis in severe traumatic brain injury: a neuropsychological study with the Wechsler adult intelligence scale (WAIS-III)].

OBJECTIVE

To evaluate the utility of the Wechsler adult intelligence scale III (WAIS-III) as a measure of intelligence after severe brain injury, and to elucidate prognostic factors associated with intelligence coefficients (IQs).

METHODS

Forty-six patients (age: 27.4 +/- 12.8 years) attending our service after a severe head injury were included in our study (chronicity: 315.3 +/- 330 days after injury). All patients were assessed with the WAIS-III. WAIS-III IQs were correlated (Pearson and Spearman) with clinical and demographic data. A significance level of p < 0.05 was used in all comparisons. IQs between 1 and 2 standard deviation (SD) below normative data were considered "mild abnormal" while indexes below 2 SD were considered "abnormal".

RESULTS

Only eleven patients (25 %) showed normal total IQ with predominance of manipulative (77.7 %) compared to verbal (64.5 %) impairment. Thirty-eight patients (95 %) had difficulties in speed processing, thirty-six (85.6 %) had problems with working-memory, twenty-five (62.5 %) showed impairments in perceptual organization, and twenty-six (62 %) had verbal comprehension deficits. WAIS-III IQs showed significant correlations with length of coma and posttraumatic amnesia duration (p < 0.05).

CONCLUSIONS

The WAIS-III is a valid and sensible tool to detect cognitive deficits associated with brain injury. Almost all patients with severe brain injury show abnormal IQs with a slow processing speed as predominant symptom. Length of coma and posttraumatic amnesia seems to be the most relevant parameter related to intelligence in severe brain-injured patients.