Sudomotor dysfunction in autoimmune autonomic ganglionopathy.

BACKGROUND: Autoimmune autonomic ganglionopathy is characterized by impairment of multiple autonomic domains of which sudomotor function is among the most common. Many patients with this disorder have difficulties with thermoregulation and anhidrosis. Our objective was to characterize the distribution and severity of sudomotor dysfunction in this disorder.
METHODS: Sudomotor function was analyzed in a cohort of 21 patients with ganglionic alpha3 nicotinic acetylcholine receptor (nAChR) antibody positive autoimmune autonomic ganglionopathy. Standard measurements of sudomotor function were used including the Thermoregulatory Sweat Test and Quantitative Sudomotor Axon Reflex Test.
RESULTS: The clinical presentation in all patients was characterized by widespread sudomotor dysfunction. Sudomotor impairment was predominantly postganglionic in 17 of the 21 patients studied. Higher ganglionic alpha3 nAChR antibody levels resulted in progressive postganglionic predominant dysfunction (postganglionic, r = 0.637, p = 0.002; mixed ganglionic, r = 0.709, p < 0.001). The pattern of anhidrosis on Thermoregulatory Sweat Testing was consistent with a ganglionopathy in the majority of patients (14 of 21) and a distal pattern in a minority of patients (8 of 21). These patterns of anhidrosis coupled with increasing postganglionic dysfunction in a proximal to distal pattern (foot > distal leg > proximal leg > forearm) indicate lesions at both the ganglia and distal axon of the postganglionic sudomotor sympathetic neuron.
CONCLUSIONS: Our data characterize the unique sudomotor dysfunction in autoimmune autonomic ganglionopathy as widespread, predominantly postganglionic, and a result of lesions at both the ganglia and distal axon. This study provides important support to the hypothesis that this disorder represents a ganglionic neuropathy.