Diagnostic accuracy of acute vestibular syndrome at the bedside in a stroke unit

L. Chen, W. Lee, B. R. Chambers, H. M. Dewey

Acute vestibular syndrome may be due to vestibular neuritis (VN) or posterior circulation strokes. Bedside ocular motor testing performed by experts is superior to early MRI in excluding strokes. We sought to demonstrate that differentiation of strokes from VN in our stroke unit is reliable. During a prospective study at a tertiary hospital over 1 year, patients with AVS were evaluated in the emergency department (ED) and underwent admission with targeted examination: gait, gaze-holding, horizontal head impulse test (hHIT), testing for skew deviation (SD) and vertical smooth pursuit (vSP). Neuroimaging included CT, transcranial Doppler (TCD) and MRI with MR angiogram (MRA). VN was diagnosed with normal diffusion-weighted images (DWI) and absence of neurological deficits on follow-up. Acute strokes were confirmed with DWI. A total of 24 patients with AVS were enrolled and divided in two groups. In the pure vestibular group (n = 20), all VN (n = 10/10) had positive hHIT and unidirectional nystagmus, but 1 patient had SD and abnormal vertical smooth pursuit (SP). In all the strokes (n = 10/10), one of the following signs suggestive of central lesion was present: negative hHIT, central-type nystagmus, SD or abnormal vSP. Finding one of these was 100% sensitive and 90% specific for stroke. In the cochleovestibular group (n = 4) all had normal DWI, but 3 patients had central ocular motor signs (abnormal vertical SP and SD). Whilst the study is small, classification of AVS in our stroke unit is reliable. The sensitivity and specificity of bedside ocular motor testing are comparable to those previously reported by expert neuro-otologists. Acute cochleovestibular loss and normal DWI may signify a labyrinthine infarct but differentiating between different causes of inner ear dysfunction is not possible with bedside testing.