Evaluation of the Diagnostic Value of Video-oculography in CANVAS Neuronopathies

Study Overview
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Brief Summary
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Cerebellar ataxia syndrome with neuropathy and vestibular areflexia (CANVAS) is a genetic pathology of recent discovery (bi-allelic expansion in intron 1 of the RFC1 gene with AAGG repetition). The clinical picture is protean, associating a neuronopathy, a bilateral vestibulopathy evidenced by an alteration of the oculovestibular reflex (VOR), an atrophy of the cerebellum and a chronic cough. In the initial stage of the disease the clinical picture is heterogeneous and often incomplete. Ataxia at the beginning of the disease may be the consequence of peripheral nervous system involvement (neuronopathy) and the cerebellar syndrome may manifest itself clinically late. Eye movement involvement in central nervous system pathologies is common (4). Oculomotor abnormalities are often subclinical and sometimes exclusively identifiable by an instrumental study, video-oculography (VOG) (5). VOG is a non-invasive examination of eye movements, which is increasingly used in the differential diagnosis of neurodegenerative syndromes (6). This examination allows, among other things, to identify oculomotor anomalies, even discrete and asymptomatic, by studying the combined movements of the eyes and the oculocephalic movements. The study of oculomotricity by VOG can therefore potentially contribute to the early differential diagnosis of ataxiating neuropathies, including CANVAS, by revealing infra-clinical oculomotor abnormalities correlated with a cerebellar expectation (knowing the role of the dorsal vermis in the precision of saccades and pursuits).

Official Title
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Evaluation of the Diagnostic Value of Video-oculography in CANVAS (Cerebellar Ataxia With Neuropathy and Vestibular Areflexia Syndrome) Neuronopathies

Conditions
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Cerebellar Ataxia

Intervention / Treatment
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* Other: None, pure observationnal study


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients followed at the University Hospital of Nîmes between 2018-2021 Age > 18 years Patients with CANVAS with genetic confirmation (RFC1 gene mutation) Patients with axonal neuropathy, autoimmune neuronopathy and anti-MAG neuropathy Healthy controls

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Patients with CANVAS with genetic confirmation<br>Patients with CANVAS with genetic confirmation (RFC1 gene mutation) | Other: None, pure observationnal study<br>* None, pure observationnal study<br>|
| others patients<br>Patients with axonal neuropathy, autoimmune neuronopathy and anti-MAG neuropathy | Other: None, pure observationnal study<br>* None, pure observationnal study<br>|
| Healthy controls<br>Patients without CANVAS or other neuropathy | Other: None, pure observationnal study<br>* None, pure observationnal study<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| jerky pursuits | Comparison of video oculography results (saccadic pursuits) of patients with a diagnosis of CANVAS with those of the other groups | Baseline, Day 0 | 
| gaze evoked nystagmus | Comparison of video oculography results (gaze evoked nystagmus) of patients with a diagnosis of CANVAS with those of the other groups | Baseline, Day 0 | 
| down beat nystagmus | Comparison of video oculography results (down beat nystagmus) of patients with a diagnosis of CANVAS with those of the other groups | Baseline, Day 0 | 
| rebound nystagmus | Comparison of video oculography results (rebound nystagmus) of patients with a diagnosis of CANVAS with those of the other groups | Baseline, Day 0 |