Brain potentials associated with movement in traumatic brain injury

NeuroMuscular Retraining Clinic, Department of Rehabilitation Medicine, Madison, WI 53705.

Brain potentials may be used to assess the functional abnormalities that underlie impairments of movement. The purpose of this article is to illustrate the usefulness of examining these potentials. In addition to an overview of the topic, the article includes a report of a study demonstrating that there were differences between the brain potentials of five patients with traumatic brain injury and those of four healthy control subjects. All five patients were in the postacute phase of hemiplegia. Slow cortical potentials associated with simple goal-directed forearm and finger movements were recorded from frontal and parietal electrodes. Two seconds of movement-related electroencephalographic activity (movement-related potential) were recorded. The patients showed reduced brain potentials for movements associated with their paretic limb and, to a lesser extent, reduced brain potentials for movements associated with their nonparetic limb. The waveforms obtained from the patients were unusual, with uncharacteristic cross-cortical movement-related potential correlations associated with specific electrode configurations, as well as with specific movement conditions. Brain potentials associated with the fore-period interval of a simple reaction time paradigm were later recorded in two of the patients with traumatic brain injury and in a control subject to help determine the functional significance of the relative positivity apparent in their movement-related potential data. This preliminary study indicates that electroencephalographic potentials obtained during the preparation for and execution of movement can provide information regarding the basis for motor dysfunction.