Mild head injury.

The pathology of mild head injury, its common behavioral sequelae, the nature of the recovery process, and the psychosocial consequences are reviewed. Acceleration-deceleration head trauma, causing brief unconsciousness, and leaving no frank neurological deficit, is associated in primates with axonal and terminal degenerative changes in brain stem nuclei. Although the presence of clinical demonstrable neurological abnormality increases the likelihood of subsequent deficits, their absence does not guarantee full recovery. Among mildly injured children, the relationships between persistent behavioral deficits and their age of onset correspond closely with those observed in children with overt damage, making it unlikely that psychological-behavioral deficits are attributable to non-neurological aspects of the injury. Deficits observed include distractability, irritability, headaches, inability to maintain a prior level of cognitive competence, and impulsivity. Although longer periods of unconsciousness are associated with permanent memory deficits, minimal unconsciousness is also followed by consistent deficits in complex memory tasks. Detailed neuropsychological testing of mildly injured children has revealed persisting deficits even after 5 years. Furthermore, deficits arising from repeated injuries are cumulative. The importance of adequate neuropsychological assessment and accurate information to the patient are stressed as important in helping satisfactory adjustment.