Video head impulse test findings in patients with peripheral myelin protein 22 related neuropathies

Vestibular impairment may be present in and contribute to imbalance in patients with hereditary neuropathies. We examined the vestibulo-ocular reflex (VOR) characteristics in peripheral myelin protein 22 neuropathies using the video head-impulse test (vHIT).

23 patients with Charcot-Marie-Tooth disease 1A (CMT1A) and 17 with hereditary neuropathy with liability to pressure palsies (HNPP) were recruited. Three-dimensional vHIT was performed. VOR-gain and latency, refixation-saccade prevalence and first-saccade amplitude, onset-latency, peak-velocity and duration were examined and compared against age-matched controls.

In CMT1A and HNPP gait imbalance was reported in 78.3 % and 58.8 % of patients, resulting in recurrent falls in 65.2 % and 23.5 %. Reduced VOR-gain affecting the posterior-canals (PCs) was found in 47.8 % of CMT1A and 11.7 % of HNPP patients. First saccade amplitude and peak-velocities higher in horizontal-canal (HC) and PC in the CMT1A group compared to controls (p < 0.05). In HNPP, first saccades were larger in HC and anterior-canal (AC) planes; saccade peak-velocity was higher in AC and PC planes compared to controls (p < 0.05). In CMT1A, VOR-gain impairment was associated with higher Charcot-Marie-Tooth Examination Score, longer disease duration, and higher total Overall Neuropathy Limitation Scale score (p < 0.05) and VOR-gain was lower for PC in patients with a history of recurrent falls (p < 0.05). VOR-latency was significantly longer in HC and PCs in CMT1A compared to controls (p < 0.05).

VOR impairment and slowing of the VOR-latency is found in CMT1A but not the HNPP cohort. These findings may relate to demyelinating processes affecting the vestibular nerves and thus the VOR pathways.

VHIT allows detection of VOR impairment which could be an additional contributor to imbalance and falls in patients with CMT1A.