[Ultrasound diagnosis of Charcot-Marie-Tooth disease]

Charcot-Marie-Tooth (CMT) disease is a clinically and genetically heterogeneous group of diseases with over 45 different causative gene mutations identified. Nerve conduction studies are important for the classification and diagnosis of CMT, whereas ultrasound (US) is increasingly used to assess the peripheral nerves of patients with CMT, as a complement to neurophysiological studies. Recent ultrasound assessment reports of peripheral nerves in CMT are summarized here. An ultrasound finding of CMT1A, which is the most common demyelinating subtype of CMT, is characterized by uniform enlargement of peripheral nerves and nerve roots. Patients with CMT1B (MPZ mutation) also have larger nerves than normal subjects do. Peripheral nerves of patients with CMT2, which is an axonal type of CMT, are slightly larger than those of normal subjects. Focal enlargement of nerves at entrapment sites is a characteristic US finding of hereditary neuropathy with liability to pressure palsy. US findings of CMT are thus subtype-specific. Therefore, the assessment of nerve US may become a useful supporting tool for the diagnosis of CMT subtypes.