Case Summary
An 85-year-old man suffered from a 20-year history of idiopathic sensory neuronopathy (figure). Neurologic examination was characterized by severe sensory ataxia needing bilateral support during walking, subtle dysarthria, and reduced sensation for all modalities. Bedside head impulse test (HIT) revealed vestibular areflexia (video 1), arising suspicion of cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS), then confirmed by the presence of biallelic expansion in RFC1 gene.1 Clinical sensory involvement can be the only manifestation in some CANVAS patients,2 and HIT, although overlooked in neurologic examination, should be performed in all patients with sensory ataxia to raise suspicion of CANVAS.
Figure. Brain MRI of CANVAS Patient.
Brain MR T1-weighted, midsagittal image shows cerebellar vermian atrophy. CANVAS = cerebellar ataxia, neuropathy and vestibular areflexia syndrome.
Bedside Head Impulse Test is an easy, quick and efficient tool to examine vestibular-ocular reflex. The rapid rotation of the head in both directions revealed the presence of abnormal catch-up saccades to move the eyes back on visual target, and as a consequence of bilateral vestibular areflexia. Download Supplementary Video 1 (31.1MB, wmv) via http://dx.doi.org/10.1212/000541_Video_1
Appendix. Authors
Study Funding
A. Cortese thanks Medical Research Council (MR/T001712/1), Fondazione CARIPLO (2019-1836), Italian Ministry of Health Ricerca Corrente 2018-2019 and 2020 and the Inherited Neuropathy Consortium (INC) for grant support.
Disclosure
The authors declare no financial or other conflicts of interest. Go to Neurology.org/NG for full disclosures.
References
- 1.Cortese A, Simone R, Sullivan R, et al. Biallelic expansion of an intronic repeat in RFC1 is a common cause of late-onset ataxia [published correction appears in Nat Genet. 2019 May;51(5):920]. Nat Genet 2019;51:649–658. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Cortese A, Tozza S, Yau WY, et al. Cerebellar ataxia, neuropathy, vestibular areflexia syndrome due to RFC1 repeat expansion. Brain 2020;143:480–490. [DOI] [PMC free article] [PubMed] [Google Scholar]
Associated Data
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Supplementary Materials
Bedside Head Impulse Test is an easy, quick and efficient tool to examine vestibular-ocular reflex. The rapid rotation of the head in both directions revealed the presence of abnormal catch-up saccades to move the eyes back on visual target, and as a consequence of bilateral vestibular areflexia. Download Supplementary Video 1 (31.1MB, wmv) via http://dx.doi.org/10.1212/000541_Video_1