COMMENTARY: Measurement of Recovery after Traumatic Brain Injury: A Cognitive-Neuropsychological Comparison of the WAIS-R with the Cognitive Assessment System (CAS) in a Single Case of Atypical Language Lateralization.

A 20-year-old preferentially left-handed male suffered an extensive right, focal, medial, prefrontal hematoma and contusion with associated swelling, and an initially undetected progressive loss of consciousness following trauma to the forehead. Performance on the Cognitive Assessment System (CAS) at 1 and 6 months after traumatic brain injury was compared with performance on the WAIS-R at 6 months post-injury. The patient demonstrated significant residualized impairment on selected subtests of the CAS at 6 months post-injury (all ps < 0.05). The patient was also significantly impaired on the Information, Vocabulary, Arithmetic and Comprehension verbal subtests of the WAIS-R. The magnitude of these WAIS-R subtest discrepancies occurred with a low base rate (< 1%) in the WAIS-R standardization sample. In addition there was a significant VIQ versus PIQ discrepancy favouring PIQ of a magnitude occurring in less than 5% of the WAIS-R standardization sample. These findings could not be explained on the basis of any prior learning disability, poor educational opportunities, medication use, response bias, confabulation, or low level of general ability. The low scores on the verbal subtests of the WAIS-R in conjunction with the impairment on the CAS subtests are highly suggestive of lasting frontal-executive dysfunction in this patient. Incidental findings of persisting anomia, impaired processing of proverbs, acalculia, and fluctuating verbal attention, as well as impaired retrieval of verbal information in the context of intact PIQ and superior constructional praxis suggest some degree of bilateral representation of linguistic functions. The differential assessment of cognitive domains by these two instruments as well as theoretical concordance in the pattern of results is also addressed. [ABSTRACT FROM AUTHOR]