BACKGROUND: Executive dysfunction is one of the most destructive sequelaeof closed head injuries (CHI), often impeding or even preventing the patient's return to normal functioning.On the basis of extensive clinical testing of patients with neurobehavioral disturbances resulting fromCHI, the authors propose a new typology of executive dysfunction based on the primary behavioral distinctionbetween active ('acting without thinking') and passive ('thinking without acting') forms of executivefunction disorder. MATERIAL/METHODS: Two patients were selected for detailed presentation. Both presentwith mild to moderate motor and cognitive symptoms resulting from closed head injury. The medical historiesof the two patients are similar (educated professionals, mid-40s, married with children, injuries sufferedin a traffic accident, 2 months in coma) except for the location of focal injuries. RESULTS: Despiteconsiderable progress in rehabilitation, the extent of functional disorder is disproportionately largein comparison to the degree of objective disability measured by standard instruments. It is suggestedthat the reason for this disparity lies in executive dysfunction. In particular, a model for executivefunctioning will be presented to explain why and how selective destruction of particular anatomical/functionalcomponents leads to the behavioral consequences known as 'executive dysfunction'. CONCLUSIONS: Executivedysfunction is a distinct clinical syndrome which occurs in at least two distinguishable varieties, activeand passive.

Keywords: Accidents, Traffic, Attention, Behavior, Brain Concussion, Cognition Disorders, Head Injuries, Closed, Memory, Psychomotor Performance, Rehabilitation, Syndrome, Time Factors