Charcot Marie Tooth Disease. A Single Disorder?

International audiencePeripheral neuropathies are subdivided into acquired and hereditary transmitted disorders.Among hereditary peripheral neuropathies, the most frequent is Charcot-Marie-Tooth disease (CMT).We will describe below, in detail, this disorder and its different forms.Charcot-Marie-Tooth disease constitutes a clinically and genetically heterogeneous group ofhereditary motor and sensory peripheral neuropathies. On the basis of electrophysiologic propertiesand histopathology, CMT has been divided into primary peripheral demyelinating (type 1) andprimary peripheral axonal (type 2) neuropathies. The demyelinating neuropathies classified as CMTtype 1, also known as HMSN I, are characterized by severely reduced motor nerve conductionvelocities (NCV) (less than 38 m/s) and segmental demyelination and remyelination with onionbulb formations on nerve biopsy. The axonal neuropathies classified as CMT type 2, also known asHMSN II, are characterized by normal or mildly reduced NCVs and chronic axonal degeneration andregeneration on nerve biopsy. Among the CMT1 group, there are X-linked, autosomal dominant andautosomal recessive forms of CMT.The typical presenting symptom is a weakness of the feet and ankles. The initial physical findingsare depressed or absent tendon reflexes with a weakness of foot dorsiflexion at the ankle. The typicalaffected adult has a bilateral foot drop, symmetrical atrophy of muscles below the knee (stork legappearance), pes cavus, atrophy of intrinsic hand muscles, especially the thenar muscles of the thumb,and absent tendon reflexes in both upper and lower extremities. The life span is not decrease