The investigator wishes to evaluate the prevalence of urinary symptoms in patients diagnosed with Cerebellar Ataxia, Neuropathy, Vestibular Areflexia Syndrome (CANVAS). As much as one third of patients living with CANVAS experience symptoms of urinary system dysfunction. The primary objective of this study is to evaluate the incidence of urinary symptoms in these patients, as well as the potential complications that might occur at the level of the upper and lower urinary system. The investigator also wishes to analyse the connection between the severity of the neurological deficits, the presence of dysautonomia and the presence of urinary dysfunction. To that end, the data collected in the study will concern : a detailed neurological examination including SARA (Scale for the assessement and rating of ataxia) scale assessement, laboratory tests of the renal function, dysautonomia tests with Sudoscan and research of orthostatic hypotension, urinary function questionnaires, dysautonomia questionnaire, urodynamic tests and urinary system ultrasound.