Vestibular impairment in patients with Charcot-Marie-Tooth disease

Objective: This case-control study aimed to determine whether the imbalance in Charcot-Marie- Tooth (CMT) disease is caused only by reduced proprioceptive input or whether the involvement of the vestibular nerve is an additional factor. Methods: Fifteen patients with CMT disease (aged 48 ± 17 years; 8 women) underwent cervical vestibular-evoked myogenic potentials, which reflect otolith-spinal reflex function, and quantitative horizontal search-coil head-impulse testing, which assesses the high-acceleration vestibulo-ocular reflex of the semicircular canals. Results: Relative to healthy age-matched control subjects, cervical vestibular-evoked myogenic potentials were found to be impaired in 75% of patients (average p13 latency: 23.0 ± 2.7 milliseconds, p = 0.01; average n23 latency: 29.0 ± 1.8 milliseconds, p 5 0.01) and the quantitative head-impulse test in 60% of patients (average gain ± 1 SD: 0.67 ± 0.24, p < 0.001). All patients with head-impulse test impairment also showed cervical vestibular-evokedmyogenic potential abnormalities, while the reverse was not true. Conclusions: We conclude that the neuropathic process in patients with CMT disease frequently involves the vestibular nerve and that cervical vestibular-evoked myogenic potentials may be more sensitive than quantitative head-impulse testing for detecting vestibular involvement, in particular at an early disease stage.