TRAUMATIC BRAIN INJURY

Abstract

Very severe traumatic brain injury (TBI) can cause persistent functional limitations in visual-motor and cognitive functions which may have consequences for fitness to drive. On-road driving performance in this population is significantly related to performance on neuropsychological tests of attention and information processing. This particularly concerns basic “operational” driving tasks like brake reaction time, visual search time, and lateral position control. Many drivers in this population, however, succeed in compensating effectively for these functional limitations, presumably because higher-order “tactical” aspects of driving allow them to anticipate and avoid driving situations which would be too demanding. To be able to assess compensatory potential, two test drives in an advanced driving simulator are included in the neuropsychological assessment of fitness to drive. The tests and the context in which they are used are described. By means of three case studies with very severe TBI the additional value of the driving simulator tests is illustrated and discussed. Test drives in a driving simulator for the assessment of brain-damaged drivers have not yet been properly validated and standardized. As an addition to a neuropsychological examination, a driving test in a realistic driving simulator can be a useful tool to assess (lacking) compensatory driving skill in brain-damaged drivers. In the Swing Drive the authors assess the operational skill of lateral position control and the tactical skill of controlling speed in response to changing motivation and operator capacities. The test requires steering at various speeds on a winding country road with alternating left-right curves and a continuous stream of traffic from the opposing direction. In various conditions the average lateral position, the standard deviation of lateral position, lane crossings left and right, and collisions with other traffic are computed. In the City Drive the authors use a city and route developed in research on intersection complexity and advanced driver assistance systems (ADAS) in older drivers. The authors assess practical fitness to drive based on observation of speed choice, lateral and longitudinal position control, viewing behavior, gap acceptance, application of priority rules, etc. in a variety of road and traffic situations as they develop during the drive. The simulator system of ST Software B.V. is used. It contains the design tools to create simulated road environments and the runtime modules required for real-time simulation. Simulation of traffic is based on ‘autonomous agents’ technology which models the simulated participants (i.e., all traffic surrounding the simulator driver) as self-governing intelligent objects that show natural and normative driver behavior.