Sympathetic sudomotor function and amyotrophic lateral sclerosis

INTRODUCTION: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder affecting motor neuron cells in the cerebral cortex, brain stem and spinal cord. Autonomic nervous system involvement is not a recognized feature of the disease, nonetheless, autonomic dysfunction has been reported in severely affected patients. The aim of this study was to evaluate sympathetic sudomotor function in ALS patients, employing the sweat imprint test. METHODS: Twenty-four ALS patients and 25 controls, matched for sex and age, were included. In total, 34 hands and 35 feet in controls, and 29 hands and 30 feet in the ALS population, were investigated. RESULTS: No inter-side difference was found in controls or in ALS patients. The mean number of sweat drops/cm(2) Was comparable in both populations. However, six ALS patients had a lower count on the hand than on the foot, which was never observed in controls. Furthermore, in the ALS population, five hands and three feet showed values below the lower limit of normal. The abnormalities were more frequent in very weak limbs, and could be ascribed to lack of use. CONCLUSION: Although significant sudomotor hypofunction does not occur in ALS, mild subclinical changes can be observed in weak limbs.