Reaction time of patients with Parkinson's disease, with reference to asymmetry of neurological signs.

Electromyographic reaction times of the left and the right finger extensor muscles in extension movement of the wrist were examined in 42 patients with Parkinson's disease, and 20 normal subjects. Compared to the normal subjects and the patients with neurological signs confined to the right side, the patients with neurological signs on the left side or on both sides showed slowing of reaction times regardless of the side of responding hand. The patients with asymmetry of bilateral neurological signs showed slower RTs on the more affected side.