Autonomic response to auditory and visual stimulation in severely brain-injured adults.

Abstract

The clinical utility of electrodermal response measures as a predictor of outcome from traumatic vegetative state was investigated. Electrodermal potential data were obtained from five subjects in acute vegetative state at 1 to 3 months post-trauma (Acute group), five subjects in persistent vegetative state at more than 1 year post-trauma (PVS group), five subjects who were more than 1 year post-trauma and had recovered from vegetative state (RVS group), and 10 normal subjects (Control group). Measures included startle response amplitude, baseline lability, habituation and orientation to tones, responses to famous faces and written commands, and total number of skin potential responses. In addition, subjects in the Acute group were reassessed with respect to clinical outcome at 6 months post-trauma. Results revealed significant group differences between the Control group and each of the brain-injured groups in startle response amplitude, baseline lability, and total number of responses. The RVS group had significantly larger startle response amplitudes than the PVS group. Some subjects in the PVS group and all subjects in the Acute group exhibited no startle response on one or more days of testing. Significant group differences also were found for habituation and orientation. Habituation was present in 80% of the Control and RVS subjects, 20% of the Acute subjects and 0% of the PVS subjects, and orientation was present in 80% of the Control subjects, 20% of the Acute and RVS subjects and 0% of the PVS subjects. Group variance in startle response amplitude, baseline lability and total number of responses was significantly greater in the Control group compared with the brain-injured subject groups. In the Acute group, a larger startle response amplitude, greater baseline lability, a greater total number of electrodermal responses, and habituation and orientation were associated with a positive outcome at 6 months post-trauma. These results indicate electrodermal responsiveness is generally reduced following traumatic brain injury, even in subjects with a relatively good recovery from vegetative state. Greater electrodermal activity in early vegetative state may be associated with better potential for recovery.