CANVAS syndrome case 1 Written by Deepseek AI on 07-08-2026

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Introduction

CANVAS syndrome (Cerebellar Ataxia, Neuropathy, and Vestibular Areflexia Syndrome) is a rare, late-onset neurological disorder characterized by a triad of progressive cerebellar ataxia, sensory neuropathy, and bilateral vestibular areflexia. Case 1 represents a classic presentation of this condition, highlighting the diagnostic challenges and clinical features that define this syndrome.

Clinical Presentation

A 62-year-old male presented with a 6-year history of progressive imbalance and unsteady gait. The patient reported frequent falls and a sensation of dizziness, particularly when walking in the dark or on uneven surfaces. He also complained of oscillopsia (the sensation that objects are bouncing or moving) during walking and quick head movements. There was no significant family history of neurological disease.

Neurological Examination

On examination, the patient demonstrated marked gait ataxia with a broad-based, unsteady stride. Romberg test was positive, indicating impaired proprioception. Cranial nerve examination revealed bilateral gaze-evoked nystagmus and a failure of the vestibulo-ocular reflex (VOR) on head thrust testing. Limb coordination tests showed dysmetria and intention tremor. Sensory examination revealed reduced vibration sense and proprioception in the lower extremities, consistent with a large fiber sensory neuropathy. Deep tendon reflexes were diminished in the ankles but otherwise normal. Muscle strength was preserved. Cognitive function was intact.

Diagnostic Workup

The diagnostic workup confirmed the clinical suspicion of CANVAS syndrome:

• Video Head Impulse Test (vHIT): Showed significantly reduced gains in all three semicircular canals bilaterally, confirming bilateral vestibular areflexia.
• Nerve Conduction Studies (NCS): Revealed a pure sensory axonal neuropathy with reduced or absent sensory nerve action potentials in the lower limbs. Motor studies were normal.
• Brain MRI: Demonstrated mild to moderate cerebellar atrophy, predominantly affecting the vermis and flocculonodular lobe. No brainstem or other structural lesions were noted.
• Genetic Testing: Targeted testing for the RFC1 gene revealed a biallelic intronic (AAGGG) repeat expansion, confirming the diagnosis of CANVAS syndrome.

Discussion

Case 1 exemplifies the classic clinical triad of CANVAS syndrome: cerebellar ataxia, sensory neuropathy, and bilateral vestibular areflexia. The presence of all three components is required for a definitive clinical diagnosis, though the onset may be staggered, with ataxia and imbalance often the first symptoms. The identification of biallelic repeat expansions in the RFC1 gene has revolutionized the understanding of this condition, which is now recognized as a common cause of late-onset cerebellar ataxia.

Treatment remains largely symptomatic and multidisciplinary, involving physical therapy for gait and balance training, vestibular rehabilitation exercises, and strategies to prevent falls. There are currently no disease-modifying therapies for CANVAS syndrome. Prognosis is variable, but the condition is slowly progressive over decades, typically not reducing life expectancy.