Autonomic dysfunction in SCN9A-associated primary erythromelalgia

Primary erythromelalgia (EM) is an autosomal dominant disorder caused by mutations of SCN9A. It is clinically characterized by reddish discoloration and episodic burning sensation of distal extremities triggered by warmth. We report a 49-year-old male with primary EM caused by SCN9A mutation (p.F216S), in whom an autonomic reflex screening test revealed a mild sudomotor dysfunction.