Bedside Head Impulse Test: A Useful Tool for Patients With Sensory Ataxia.

Case Summary

An 85-year-old man suffered from a 20-year history of idiopathic sensory neuronopathy (figure). Neurologic examination was characterized by severe sensory ataxia needing bilateral support during walking, subtle dysarthria, and reduced sensation for all modalities. Bedside head impulse test (HIT) revealed vestibular areflexia (video 1), arising suspicion of cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS), then confirmed by the presence of biallelic expansion in RFC1 gene.[1] Clinical sensory involvement can be the only manifestation in some CANVAS patients,[2] and HIT, although overlooked in neurologic examination, should be performed in all patients with sensory ataxia to raise suspicion of CANVAS.

Figure

Brain MRI of CANVAS Patient

Brain MR T1-weighted, midsagittal image shows cerebellar vermian atrophy. CANVAS = cerebellar ataxia, neuropathy and vestibular areflexia syndrome.

Bedside Head Impulse Test is an easy, quick and efficient tool to examine vestibular-ocular reflex. The rapid rotation of the head in both directions revealed the presence of abnormal catch-up saccades to move the eyes back on visual target, and as a consequence of bilateral vestibular areflexia. Download Supplementary Video 1 via http://dx.doi.org/10.1212/000541_Video_1