Dados do Trabalho

Título

CANVAS: Expanding the differential diagnosis of sensory polyneuropathies/neuronopathies: positive sensory manifestations as the main complaint

RESUMO

Presentation of the Case

A 38 year male patient started with severe paresthesia in the feet that interfered with sleep and daily activities. Over the years, there was a progressive worsening, with involvement of the lower limbs up to the knees, and more recently, after 6 years of evolution, of the hands and forearms. There is also a report of chronic cough. This is a previously healthy patient, that also complained of reflux and rhinitis and no other comorbidities. No family history of peripheral neuropathy. On neurological examination, the patient had preserved muscle strength, decreased osteotendinous reflexes globally, tactile, thermal and painful hypoesthesia up to the bilateral ankles and distal hypopalesthesia. Electroneuromyography revealed a length-dependent sensory neuropathy/neuronopathy. The patient was extensively investigated and, due to the severity of his symptoms, he repeatedly sought different health services. Autoimmune, infectious, metabolic diseases and research for amyloidosis, which were normal, were excluded. The exome showed no pathogenic variants. The CANVAS search revealed a bilateral AAGGG expansion at the RFC1 gene. The propaedeutics of vestibular tests and brain MRI showed no alterations.

Discussion

The typical cerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS) is a progressive neurologic disease characterized by imbalance, sensory neuropathy and, occasionally, chronic cough and autonomic dysfunction. Its etiopathogenesis is associated with a biallelic (AAGGG) expansion in an intronic region of the RFC gene. Recently, the phenotypic spectrum associated with this mutation has been expanded and more limited phenotypes involving predominantly or exclusively one of the systems involved in balance control were described. Our patient complained essentially of a neuropathy and retrospectively we identified cough. As that pathogenic RFC1 AAGGG repeat expansions cannot be routinely detected by sequence-based multigene panels or exome sequencing, we need to be aware for this condition to order the appropriate genetic test.

Conclusion

Sensory neuropathy/neuronopathy is a challenge in clinical practice, especially when the most common acquired diseases are ruled out. Our case shows that incomplete and phenotypes of CANVAS syndrome should be considered in this scenario.

Palavras Chave

CANVAS, sensory neuropathy/neuronopathy, differential diagnosis