Cerebellar ataxia with neuropathy and bilateral vestibular areflexia syndrome

Cerebellar ataxia with neuropathy and bilateral vestibular areflexia syndrome (CANVAS) is a rare, slowly progressive neurological disorder that affects the cerebellum, peripheral nerves, and vestibular system. It is caused by biallelic intronic pentanucleotide repeat expansions (AAGGG) in the RFC1 gene. CANVAS was initially considered a sporadic condition, but it is now recognized as an autosomal recessive genetic disorder. The disease typically presents in adulthood, usually between the ages of 40 and 70, and is characterized by the triad of cerebellar ataxia (impaired coordination and balance due to cerebellar dysfunction), sensory neuropathy (damage to peripheral nerves affecting sensation), and bilateral vestibular areflexia (loss of function in both inner ear balance organs). Patients commonly experience progressive unsteadiness, oscillopsia (visual disturbance where objects appear to bounce or oscillate), impaired proprioception, and a chronic dry cough that may precede neurological symptoms by years. The combination of cerebellar, vestibular, and sensory nerve dysfunction leads to significant balance impairment that is often more severe than would be expected from any single component alone. Additional features may include autonomic dysfunction and downbeat nystagmus. Nerve conduction studies typically reveal a sensory neuronopathy (ganglionopathy), and vestibular testing confirms absent or markedly reduced vestibular responses bilaterally. Brain MRI may show cerebellar atrophy, particularly of the vermis. There is currently no disease-modifying treatment for CANVAS. Management is supportive and includes physical therapy and vestibular rehabilitation to optimize balance and mobility, occupational therapy, and assistive devices as needed. The identification of RFC1 repeat expansions as the genetic cause has significantly improved diagnostic accuracy and genetic counseling for affected families.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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