LATE CONTRALATERAL HYPERHIDROSIS IN LATERAL MEDULLARY INFARCTS

Background and Purpose This study describes unilateral increases of sw eating reactions observed in the months after contralateral medullary infarct; evaluation of sympathetic cutaneous response may help to expl ain sweating disorders. Summary of Report After the discovery of the c linical phenomenon in one case, patients admitted between 1990 and 199 3 were systematically evaluated clinically and electrophysiologically. In a group of five patients presenting with lateral or dorsal medulla ry lesions, two exhibited an increase of contralateral sweating reacti ons that appealed 6 to 8 months after stroke, were elicited by effort and exposure to heat and stress, and were more severe over the forehea d, face, and upper trunk. In one case, this was clinically associated with an absence of sweating on the side of the lesion. During the late phase after stroke, in three patients presenting with lateral medulla ry lesions, electrophysiological evaluation revealed significant asymm etry of the sympathetic skin response, which was higher on the side co ntralateral to the lesion than on the ipsilateral side. In one patient , no response could be elicited by stimulations applied on the side of the lesion. Conclusions Contralateral hyperhidrosis can be observed i n the late phase after lateral medullary infarct and is likely due to lesion of the sympathetic pathway passing through the lateral medulla, which inhibits sudomotor neurons. Evaluation of sympathetic skin resp onse may help to explain such clinical disorders.