Ann Clin Neurophysiol.  2022;24(2):84-89. 10.14253/acn.2022.24.2.84.

Anterior canal-sparing bilateral vestibulopathy in MELAS syndrome

• Kim JM
• Nam TS
• Lee SH

• KMID: 2535724
• DOI: http://doi.org/10.14253/acn.2022.24.2.84

Abstract

Vestibular dysfunction has rarely been reported in MELAS syndrome. A 40-year-old male with long-term diabetes and hearing loss experienced a stroke-like episode with hemisensory disturbance and lactic acidosis. Brain MRI showed temporo-parieto-occipital cortical lesions, and a final diagnosis was made of MELAS syndrome with the mitochondrial 3243A>G mutation. Neuro-otologic evaluations revealed anterior-canal-sparing bilateral impairments of the vestibulo-ocular reflex in the video head impulse test and no caloric paresis. This unique pattern of vestibular dysfunction may aid in diagnosing MELAS syndrome.

Keyword

Bilateral vestibulopathy; MELAS syndrome; Head impulse test

Figure

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  Fig. 1. In brain magnetic resonance imaging, a T2-weighted fluid-attenuated inversion recovery image (A) shows cortical and subcortical hyperintense lesions with gyral swelling in the right temporo-parieto-occipital and insular lobes, which could not be defined as the involvement of specific arteries (white arrows). The corresponding lesions were associated with diffusion restriction in diffusion-weighted images, hypo-/iso-/hyperintensities in an apparent diffusion coefficient sequence, and gyral enhancement in gadolinium-enhanced T1-weighted images (B-D, dotted arrows). Magnetic resonance angiography (E) reveals no relevant intracerebral arterial stenosis. A sagittal T1-weighted image (F) shows diffuse cerebellar atrophy without definite brainstem involvement.

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  Fig. 2. The video head impulse test (A) revealed decreased gains of the vestibulo-ocular reflex (VOR) in bilateral horizontal and posterior canals (HCs and PCs, respectively) combined with abnormal catch-up saccades, without anterior canal (AC) impairment (red traces). Pure-tone audiometry (B) demonstrated moderately severe sensorineural hearing loss bilaterally, by about 60 and 70 dB in the right and left ears, respectively. Note: decreased VOR gains were defined as < 0.8 and < 0.7 for the HCs and vertical canals, respectively.

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