Driving after brain injury

Journal of Rehabilitation,  April-June, 1995  by Barbara S. Handler,  Jeanne Boland Patterson

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6. Sixty-four percent of in-traffic performance was predicted by the scores on seven neuropsychological tests, which measured visual perception, scanning and attention (especially sustained attention), and several executive functions. Predictive success was highest when parking lot performance, including behavioral observations, was added to pre-driving evaluations. The simulator evaluations showed slightly higher correlation with actual driving performance than the other pre-driving evaluation measures, however, the researchers (Galski et al., 1992) stated that more testing of Cybernetic Model of Driving was needed before definitive conclusions could be drawn.

7. Although significant relationships exist between performance on the Tactual Performance Test, the Trail Making Tests, and the driving evaluator's rating (pass/fail) of the subjects in the behind-the-wheel evaluation, no correlation was found to be sufficiently strong to be a precise predictor of driving performance (Brooke, Questad, Patterson, & Valois, 1992) for individuals evaluated within three to six months of injury. (This time period was selected, because the investigators' experience showed this to be the period in which survivors of closed head injury who do not show "blatant cognitive impairments" are most likely to seek to return to driving.)

8. The high rates of traffic violations for survivors of TBI who have been evaluated at rehabilitation hospitals indicate a need for better screening and training methods for survivors of TBI who wish to return to driving (Boake, Strowmatt, & Lehmkuhl, 1993).

In summary, the research on predictors of on-the-road driving performance for individuals with TBI is inconclusive. Reaction time, driving errors and patterns of errors, vision, motor control, post-injury IQ, driver simulations, length of post-traumatic amnesia, driving experience, psychometric and neuropsychological tests, and driver evaluator ratings have all been investigated. The research suggests that a combination of neuropsychological testing, visual screening, physical functioning, and actual driving (simulations and on-the-road evaluations) is necessary to predict driving performance.

The Cognitive Behavioral Driver's Inventory

The predictive system that appears to have been most widely tested is the Cognitive Behavioral Driver's Inventory (CBDI), first described by Engum, Pendergrass, Cron, and Lambert (1988). Because ability to drive was not accurately predicted by diagnosis, pathology, loss of brain mass, or by neuropsychological tests alone, they developed and investigated the CBDI, which consists of (a) a battery of computerized and paper-and-pencil neuropsychological tests (many related to visual processing); (b) visual screening using the Keystone Driver Vision Telebinocular, which is the machine used in many state drivers' licensing offices; (c) a reaction time test focused on braking ability; and (d) an examination of visual fields. Composite cut-off scores were established for ratings of pass or fail. Initially, cutoff scores on the pre-driving battery determined whether the individual would be permitted to proceed to an on-the-road test of graduated difficulty. Failing test results were used in making referrals for additional driving training. In later follow-up studies, Lambert and Engum (1992) recommended that the Driver Performance Test be administered to subjects in addition to the existing battery. It was further recommended (Engum, Pendergrass, Cron, Lambert, & Hulse, 1988) that all individuals be allowed to attempt some portion of the on-the-road test under controlled circumstances, as in a situational assessment, even if they had failed the pre-driving battery, to help them comprehend the effects of their disability on driving safety. Of the 44 patients initially determined by a psychologist to have passed the CBDI, 42 (95.5%) passed an independent on-the-road driving test. All of the later studies by these researchers strongly recommend that the pre-driving component of the CBDI not be used exclusively to determine driving fitness. Because measurement of activities at the tactical and strategic levels was considered more subjective, an on-the-road evaluation by a qualified evaluator/instructor was deemed necessary before final recommendations were made.