[Vestibular Dysfunction in Replication Factor C Subunit 1 (RFC1) Spectrum Disorder].

More than 90% of replication factor c subunit 1 (RFC1) gene-related spectrum disorders such as cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS) have bilateral vestibular dysfunction. A case with CANVAS presented in this paper showed repeat extension of AAGGG in the intron region of the RFC1 gene, and showed bilateral vestibular dysfunction in caloric test, vestibular evoked myogenic potential, video Head Impulse Test and rotary chair test. Visual enhanced vestibulo-ocular reflex tests also revealed abnormalities, suggesting the presence of combined lesions of the cerebellum and brainstem including vestibular nuclei.