Vestibular impairment in Charcot-Marie-Tooth disease type 4C.

Charcot-Marie-Tooth disease type 4C (CMT4C) is a hereditary neuropathy with prominent unsteadiness. The objective of the current study is to determine whether the imbalance in CMT4C is caused only by reduced proprioceptive input or if vestibular nerve involvement is an additional factor. We selected 10 CMT4C patients and 10 age-matched and sex-matched controls. We performed a comprehensive evaluation of the vestibular system, including video Head Impulse Test, bithermal caloric test, galvanic stimulation test and skull vibration-induced nystagmus test. None of the patients experienced dizziness, spontaneous or gaze-evoked nystagmus, but all had significant vestibular impairment when tested when compared to controls. Seven had completely unexcitable vestibular systems and abnormal vestibuloocular reflex. There was no correlation between the degree of vestibulopathy and age or clinical severity. Significant vestibular impairment is a consistent finding in CMT4C and is present early in disease evolution. The profound imbalance that is so disabling in these patients may result from a combination of proprioceptive loss and vestibular neuropathy, and this would modify the recommended rehabilitation strategies. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.