Demyelinating X-linked Charcot-Marie-Tooth disease: unusual electrophysiological findings.
X-linked Charcot-Marie-Tooth disease (CMT-X) is caused by mutations of connexin-32 (Cx-32), which encodes a gap-junction protein. Whether the neuropathy is primarily demyelinative or axonal remains to be established. We report findings of prominent demyelination in a 71-year-old woman with late-onset disease. Electrophysiological studies revealed a nonuniform slowing of motor conduction velocities and dispersion of compound action potentials indicative of a demyelinating process which was confirmed by nerve biopsy. Such electrophysiological features are unusual in hereditary neuropathies and are more commonly found with acquired chronic demyelinating neuropathies. A systematic search confirmed the molecular genomic diagnosis of CMT-X, illustrating the value of such tests in sporadic cases. Severity of clinical symptoms and signs may vary with age and sex of the patient. The pathology of CMT-X in other reported cases has been variably interpreted as axonal, demyelinating, or showing both features. Our observations emphasize the demyelinative nature.
Tabaraud
F
F
Department of Neurology, University Hospital, 87042 Limoges, France.
Lagrange
E
E
Sindou
P
P
Vandenberghe
A
A
Levy
N
N
Vallat
J M
JM
D000200:Action Potentials; D000368:Aged; D002607:Charcot-Marie-Tooth Disease / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology*; D003711:Demyelinating Diseases / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology*; D004594:Electrophysiology; D005260:Female; D008040:Genetic Linkage; D006801:Humans; D009046:Motor Neurons / Q000502:physiology; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D009431:Neural Conduction; D013997:Time Factors; D014960:X Chromosome / Q000235:genetics*