[Cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS): a case report]

Cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS) is a rare form of multisystem ataxia defined by a triad of cerebellar impairment, bilateral vestibular hypofunction, and somatosensory deficit. Here we present a patient with CANVAS. A 76-year-old woman whose parents were cousins had noted slowly worsening gait imbalance since age 67. Peripheral sensory impairment was evident since age 73. When examined at 74, she had a frequent cough. The neurologic examinations showed scanning speech, downbeat nystagmus, pursuit eye movements with saccadic features, truncal ataxia, and mild dysmetria of the extremities. The Romberg test was positive. Light touch, pinprick, and vibration sensation were absent in the distal lower limbs, where allodynia could be demonstrated. Ankle jerk reflex was diminished. Muscle strength was normal. Nerve conduction studies disclosed absence of sensory nerve action potentials in all limbs, while motor conduction was normal except for decreased amplitude of left median and bilateral ulnar nerve compound motor action potentials. MRI of the brain demonstrated cerebellar atrophy. The eye tracking test for the smooth pursuit and visually enhanced vestibulo-ocular reflex test demonstrated functional impairments. Both the bithermal caloric test and the video head impulse testing showed sever hypofunction of the bilateral semicircular canal. In sum, somatosensory deficit and otoneurologic examinations indicated bilateral vestibulopathy which, together with the patient^'s and cerebellar impairment, confirmed the diagnosis of CANVAS.