Topical anesthesia: a possible treatment method for spasticity.

Topical anesthesia was applied to the skin of the leg and thigh of a hemiparesis patient resulting from embolic infarction in the middle cerebral artery. After application of the anesthesia, the angular displacement of the ankle and knee joints measured during a full gait cycle showed a substantial shift towards normal. This response indicated a reduction in muscle spasticity which was confirmed by clinical tests. Neurophysiologic studies performed on the patient suggested that the reduction in muscular hypertonicity was mediated by reduced cutaneous inputs on the alpha - gamma motoneuron interaction. This conjecture is supported by studies of other investigators performed on animals as well as humans.