Modulation of spinal motor asymmetry by neuroleptic medication of schizophrenia patients.

The effects of chlorpromazine treatment on spinal motor asymmetry was studied in right-handed chronic schizophrenia patients. Spinal motor asymmetry and lower motor neuron excitability were tested by the Hoffmann reflex recovery curve. In drug-free patients, the Hoffmann reflex recovery curve from the left leg was significantly higher than that from the right leg as in the healthy subjects. This spinal motor asymmetry disappeared and even reversed within three weeks of the neuroleptic treatment. The chlorpromazine medication lowered the left recovery curve predominantly, and slightly augmented the right recovery curve. These results do not support the hypothesis that schizophrenia may be related to an overactive, and yet functionally deficient, dominant hemisphere. It was concluded that the cooperative function of both cerebral hemispheres should be taken into consideration to explain the neural mechanisms of schizophrenia.