Autonomie responsivity following closed head injury.

It has recently been suggested that certain posttraumatic head injury patients exhibit impaired central nervous system arousal mechanisms, which may underlie or contribute to subsequent behavioral and cognitive disturbance. The present study examined skin conductance levels and responsivity in a group of 15 patients recovering from closed head injuries (CHIs) with 15 matched controls. Measurements were taken during rest periods and two activation periods. Activation periods consisted of 1) a series of 80 dB tones; and 2) a cognitive task (Symbol Digit Modalities Test). Patients exhibited significantly lower levels of skin conductance and significantly fewer responses than the control group. Group by task interactions were also significant, indicating that the control group was much more responsive during both activation periods. Skin conductance responsivity in the patient group was not found to be associated with duration of posttraumatic amnesia, behavioral disturbance, or attentional functioning, suggesting that the relationship between decreased autonomic arousal and cognitive or behavioral disturbance following CHI may be coincidental.