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Review
. 2016 Feb;6(1):61-68.
doi: 10.1212/CPJ.0000000000000215.

Proposed diagnostic criteria for cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS)

David J Szmulewicz  1 , Leslie Roberts  1 , Catriona A McLean  1 , Hamish G MacDougall  1 , G Michael Halmagyi  1 , Elsdon Storey  1
Affiliations
Review

Proposed diagnostic criteria for cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS)

David J Szmulewicz et al. Neurol Clin Pract. 2016 Feb.

Abstract

Purpose of review: Diagnosis of ataxic disorders is an important clinical challenge upon which prognostication, management, patient solace, and, above all, the hope of future treatment all rely. Heritable diseases and the possibility of affected offspring carry the added burden of portending adverse health, social and financial ramifications.

Recent findings: Cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS) is an inherited multisystem ataxia compromising cerebellar, vestibular, and sensory function. It is not uncommon, but despite early attempts the genetic defect is yet to be identified. As the search for the causative gene continues, we have found it useful to further define this syndrome in terms of its likely phenotype.

Summary: We propose staged diagnostic criteria based on the identified pathology in CANVAS. We envisage that these criteria will aid the clinician in diagnosing CANVAS and the researcher in further elucidating this complex disorder.

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Figures

Figure 1
Figure 1. Bilateral vestibulopathy shown on horizontal impulsive testing recorded on the video head impulse test in a patient with CANVAS
The head rotation stimulus is shown in black and the eye movement response is shown in red. Maximum gain of the vestibulo-ocular reflex (VOR) is less than 0.2 (normal >0.68) in each direction and compensatory “catch-up” saccades are seen following the head impulse. Inset: normal bilateral horizontal VOR gain (∼1).
Figure 2
Figure 2. Video-oculographic measurement of the visually enhanced vestibulo-ocular reflex
Top panel: normal horizontal visually enhanced vestibulo-ocular reflex (VVOR) gain (∼1) recorded using portable rapid video-oculography equipment. Vertical axis represents velocity (degrees/s) and horizontal axis represents time (s). The head rotation stimulus is shown in red and the eye movement response is shown in black. Lower panel: A reduced VVOR gain results in salvos of catch-up saccades during slow sinusoidal head rotation (0.5–1.0 Hz) in the horizontal (yaw) plane.
Figure 3
Figure 3. T1-weighted MRI illustrating the characteristic pattern of cerebellar atrophy found in CANVAS
Anterior and dorsal vermis atrophy (vermal lobules VI, VIIA, and VIIB) is seen in the midsagittal view (A), and hemispheric atrophy predominantly affecting crus I is seen in the parasagittal view (B).
Figure 4
Figure 4. Autopsy demonstration of typical pathologic features
(A) Anterior (1) and dorsal (2) cerebellar vermal atrophy. (B) Atrophic dorsal root ganglion at high magnification showing marked neuronal loss with scant residual ghost outlines (arrows), hematoxylin and eosin. (C) Cervical spinal cord cross section at low power magnification showing loss of myelinated neurons in the posterior columns (arrows), Luxol fast blue.
See this image and copyright information in PMC

References

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    1. Szmulewicz DJ, McLean CA, Rodriguez ML, et al. Dorsal root ganglionopathy is responsible for the sensory impairment in CANVAS. Neurology 2014;22:1410–1415. - PMC - PubMed
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