Dados do Trabalho

Título

Electrophysiological findings in a sample of genetically confirmed Brazilian citizens with CANVAS

Resumo

Cerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS) is a late-onset, slowly progressive neurological disorder. Despite recently described, its etiopathogenesis is already in the process of elucidation due to the identification of a biallelic intronic AAGGG repeat expansion in the RFC1 gene as the genetic cause of the disease. Meanwhile, electrophysiological findings are still to be completely described as patients receive their definitely diagnosis. Based on these findings, this study evaluated nerve conduction study and electromyography findings of genetically confirmed CANVAS patients from a single Brazilian center. In order to genetically identify this expansion, flanking polymerase chain reaction (PCR) and repeat-primed PCRs (RP-PCR) for the pathogenic allele expansion configuration in RFC1 were performed in patients with at least one clinical feature of the Syndrome. If flanking PCR did not show any product, the DNA sample would undergo RP-PCR. Biallelic AAGGG expansion was found in nineteen patients of the sample group (18%). Subsequently, confirmed CANVAS patients were submitted to electrophysiological studies (nerve conduction study and electromyography). Fifteen out of the nineteen confirmed cases were submitted to electrophysiological evaluation. Only one patient had a normal electrophysiological study and clinically presented with cerebellar ataxia related symptoms alone. Six patients (40%) had motor involvement associated with neuropathy. Notably, eight patients (53%) had exclusively sensory involvement and primarily axonal deterioration for most cases. Additionally, 6 patients were submitted to the blink test during the exam and 3 (50%) had the R2 reflex impaired. With regards to autonomic evaluation, four patients were evaluated for cutaneous response for electric, respiratory and sound stimuli. One of these patients showed diminished response to the electric stimulus. Ultimately this study aims to contribute to the understanding of the electrophysiological findings of the CANVAS patients in the Brazilian population.

Palavras Chave

Nerve conduction study; Electromyography; Neuropathy; CANVAS