Assessment of cutaneous autonomic nerve functions in leprosy

31 cases of established leprosy were studied for sweat response to acetylcholine and adrenaline injected intradermally and compared with normal areas of skin on the contralateral side in a total of 40 lesions. Sweating was measured by counting the number of blue dots which appeared on the yellow back ground of a filter paper soaked in 1% Bromophenol blue solution which represented sweat pores, whereas there was decreased, or absent sweat response in 31 lesions, there was an increased response in to acetylcholine in 7 lesions, and normal response in 2 lesions. Sweat response to adrenaline was obtained in 29 lesions. It was increased in 13 lesions all of which were anaesthetic or analgesic. Adrenergic sweating in these cases is probably a result of direct effect of adrenaline on sweat glands. Biopsy sections of 20 cases were reviewed for the histological appearance of the nerves. It was found that out of the cases who showed increased sweat response 1 had partially destroyed nerves while 2 others had intact nerves. Sweat function tests are of limited value in the diagnosis of leprosy and some autonomic function may continue in leprosy despite loss of somatic nerve function.