LAUSR

To the Editor: Charcot–Marie–Tooth (CMT) 2C is an autosomal dominant hereditary neuropathy associated with mutations in the TRPV4 gene on chromosome 12q23-241 (OMIM: 606071). Neurologic features of CMT2C include peripheral neuropathy (axonal), limb atrophy, muscle weakness, sensory loss, diaphragmatic weakness, and vocal cord paralysis.2 Respiratory features can include dyspnea, hoarse voice, and stridor.2 A confirmative diagnosis is based on molecular genetic testing. We report a case of a 57-year-old woman with CMT2C referred for a question of autonomic dysfunction. The patient presented with vocal cord paresis and tracheostomy secondary to a TRPV4 mutation. However, her primary complaint was that of severe difficulty with temperature regulation. The patient described frequent sensations of heat associated with elevated temperature and anhidrosis. To reduce symptoms, the patient relies on ice packs and copious amounts of ice water. The patient completed the autonomic reflex screen to provide quantitative measures of sudomotor, cardiovagal, and adrenergic function. Autonomic testing revealed significant sudomotor dysfunction with significantly reduced sweat volumes at the forearm (0.06 mL), proximal leg (0.018 mL), distal leg (0.012 mL), and foot (0.042 mL) (Fig. 1). Cardiovagal function was intact as evidenced by a normal heart rate response to deep breathing and Valsalva ratio in response to the Valsalva maneuver (Table 1). Similarly, adrenergic function was maintained as evidenced by a normal blood pressure response to Valsalva (present adrenergic phases), and normal heart rate and blood pressure response to head-up tilt (Table 1).