The effects of proprioceptive stimulation on cognitive processes in patients after traumatic brain injury

Objective: To investigate the hypothesis that proprioceptive stimulation may be effective in the treatment of brain injury, using neurophysiologic and neuropsychologic measures. Design: Cohort analytic study. Setting: Patients recovering from traumatic brain injury (TBI) in a neurologic rehabilitation hospital were examined. Participants: Eleven patients with TBI (Glasgow Coma Scale score > 3) and 11 healthy control subjects matched for age and education. Interventions: Subjects were examined with the event-related potential (ERP) technique during a computerized choice-reaction-time task, in which they had to discriminate between even and odd digits. There were experimental runs with and without vibratory stimuli applied to the left forearm serving a as proprioceptive stimulation. In addition, ERPs were recorded to vibratory stimuli without any additional task. Main Outcome Measures: Outcome measures included latencies and amplitudes of the P300 ERP component and of the late negative component. Results: In the passive vibration condition, both groups showed the same ERP distribution. In the choice-reaction-time task, latencies and amplitudes of the P300 differed between the 2 groups. The patient group showed longer P300 latencies, which were shortened by vibratory stimuli. In contrast, the control subjects were not affected by vibratory stimuli. Conclusion: Our findings support the hypothesis that pathologic cognitive processes after TBI can be improved by proprioceptive stimulation. Muscle vibration has positive effects on pathologically slowed cognitive processes but not in healthy subjects.