Autonomic dysfunction is a major feature of cerebellar ataxia, neuropathy, vestibular areflexia 'CANVAS' syndrome

Cerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS) is a recently recognized neurodegenerative ganglionopathy. Prompted by the presence of symptomatic postural hypotension in two patients with CANVAS, we hypothesized that autonomic dysfunction may be an associated feature of the syndrome. We assessed symptoms of autonomic dysfunction and performed autonomic nervous system testing among 26 patients from New Zealand. After excluding three patients with diabetes mellitus, 83% had evidence of autonomic dysfunction; all patients had at least one autonomic symptom and 91% had more than two symptoms. We also found a higher rate of downbeat nystagmus (65%) than previously described in CANVAS. We confirmed that sensory findings on nerve conduction tests were consistent with a sensory ganglionopathy and describe two patients with loss of trigeminal sensation consistent with previous pathological descriptions of trigeminal sensory ganglionopathy. Our results suggest that autonomic dysfunction is a major feature of CANVAS. This has implications for the management of patients with CANVAS as the autonomic symptoms may be amenable to treatment. The findings also provide an important differential diagnosis from multiple system atrophy for patients who present with ataxia and autonomic failure.