[Subacute ataxia associated with cerebellar ataxia, neuropathy and vestibular areflexia (CANVAS)]

Cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS) is a late onset neurodegenerative disorder. Its genetic basis has recently been identified in the gene encoding a subunit of the Replication Factor C (RFC1). We present the case of a 62-year-old woman who experienced a history of a biphasic presentation of imbalance and gait disorders, with rapid onset of symptoms followed by slow and progressive neurological deterioration. The diagnostic process was challenging, and numerous tests were conducted to rule out acquired and genetic causes of ataxia, leading to a diagnosis of late-onset idiopathic cerebellar ataxia. Subsequently, vestibular function tests identified severe bilateral vestibulopathy. This led to considering CANVAS among the diagnoses, which was ultimately confirmed through genetic testing (biallelic expansion of the pentanucleotide AAGGG in the RFC1 gene). This case highlights the importance of this new described genetic disease and its subacute presentation variant, emphasizing the relevance of objective vestibular function tests in idiopathic ataxias to achieve proper diagnosis and eventual genetic counseling for offspring.