LAUSR

We report on a 65-year old patient referred to our department with progressive gait ataxia and oscillopsia. Approximately 6 years before, the patient had developed an unsteadiness of gait, especially on uneven ground. Therewas no history of aminoglycoside therapy. His family history was unremarkable. On clinical examination downbeat nystagmus, bilateral horizontal gaze-evoked nystagmus and saccadic smooth pursuit were apparent. The clinical head-impulse test was pathologic to both sides. The patients' speech appeared slurred. Both triceps surae reflexeswere absent. Position sense in the lower extremities, tested at the proximal joint of Dig. I, was heavily impaired. There was only mild limb ataxiawith signs of intentional tremor in both upper extremities. Standing with eyes closed during the Romberg-test was not possible. Gait in general appeared ataxic and insecure. Taken together, there was cerebellar ataxia, neuropathy and signs of bilateral vestibulopathy, which lead to the tentative diagnosis of CANVAS (cerebellar ataxia with neuropathy and vestibular areflexia syndrome) [1]. Neuropathy was confirmed by nerve conduction studies showing afferent nerve pathology in upper and lower extremities with decreased or absent sensory nerve action potentials. Motor neurography and motor evoked potentials in the upper and lower extremities were normal. Brain andmyelon 3-Tesla MRI showed cerebellar atrophy of the upper vermis, Crus I and especially vermal lobules VI, VIIa, VIIb (Fig. 1). The flocculus appeared only slightly atrophic when compared to MRI-scans of normal agematched persons. The brainstem and myelon were unaffected. Extensive laboratory testing in serum and cerebro-spinal fluid including protein electrophoresis, vitamin B1, B6, B12, E, thyroid hormones, HbA1c, coeruloplasmin, anti-gliadin, anti-t-transglutaminase, anti-Hu, -Yo, -Ri, -CV2, -Ma1, -Ma2, -amphiphysin, was unremarkable. Genetic testing for spinocerebellar ataxia types 1,2,3,6,7, and 17 and Friedreich-ataxia, was negative as recently recommended as a requirement for establishing the diagnosis of CANVAS [1]. Video oculomotor and vestibular tests revealed pathologically weak gains of optokinetic responses, absent video-head-impulse-test responses bilaterally in all 3 semicircular canal planes (Fig. 2) and bilaterally absent vestibulo-ocular responses during whole-body horizontal rotating chair and caloric tests. Slow phase eye velocity was b1°/s over