Measures of prefrontal dysfunction after closed head injury

Tasks sensitive to frontal lobe dysfunction (delayed response, delayed alternation, object alternation, and Wisconsin Card Sort) were administered to 20 patients with post-acute closed-head injury (CHI). Time since injury varied (6 to 280 months; mean, 48 months), as did length of coma (2 hr to 120 days; mean, 38 days). Compared to normal controls, CHI patients showed no deficits on delayed response tasks, but were impaired on delayed alternation, object alternation, and the Wisconsin Card Sort Test. Analyses of the performance profiles of the CHI patients suggested that they may have difficulty in establishing set (a consequence of damage to the orbitofrontal system).