Acute Vestibular Syndrome Unmasking an -Spectrum Disorder.

Objectives: Since the discovery of biallelic pentanucleotide expansions in as the cause of cerebellar ataxia, neuropathy, vestibular areflexia syndrome, a wide and growing clinical spectrum has emerged. In this article, we report a man with acute vestibular syndrome that likely unmasked a -spectrum disorder.

Methods: Detailed clinical evaluation, neuroimaging, nerve conduction studies, evaluation of vestibular function, and short-read whole-genome sequencing and targeted long-read adaptive sequencing were performed.

Results: Clinical follow-up after acute vestibular syndrome revealed bilateral vestibular areflexia and a gait abnormality with the Scale for the Assessment and Rating of Ataxia score of 5. Brain MRI was normal while 2 electroneurography tests did not show neuropathy. However, severe cough spells raised the suspicion of a -spectrum disorder. WGS screening detected a recessive intronic pentanucleotide expansion in , which was verified and sized using long-read adaptive sequencing.

Discussion: This is an unusual presentation; oscillopsia after an acute vestibular syndrome and cough spells should alert clinicians about a -spectrum disorder, even in the absence of neuropathy and neuroradiologic abnormalities.