By Charlene Laino
BALTIMORE, Md -- October 20, 2009 -- Oculomotor signs are a more sensitive predictor of stroke than findings from magnetic resonance imaging (MRI) in patients with acute vestibular syndrome (AVS), a prospective, cross-sectional study suggests.
David Newman-Toker, MD, PhD, The Johns Hopkins School of Medicine, Baltimore, Maryland, reported the findings here on October 12 at the American Neurological Association (ANA) 134th Annual Meeting.
AVS is often due to vestibular neuritis, but also can result from vertebrobasilar strokes, he said. However, one-third of strokes associated with AVS are misdiagnosed in the emergency department, Dr. Newman-Toker said. Retrospective data suggest bedside oculomotor signs may reliably identify stroke in AVS, but prospective data have been lacking, he said.
To determine if oculomotor signs accurately predict which patients had stroke, the researchers enrolled 101 consecutive high-risk AVS patients presenting to the emergency room with 1 or more stroke risk factors.
Patients underwent structured neurological and vestibular exams, including horizontal head impulse testing of vestibulo-ocular reflex function, prism crossover testing of ocular alignment, and observation of nystagmus in different gaze positions. All also underwent neuroimaging with MRI, generally within 72 hours of symptom onset.
Results showed that a normal result on the head impulse test, a test of balance function, is a very strong predictor of stroke, with 90% specificity. Direction-changing nystagmus with eccentric gaze and skew deviation each occurred in about 25% of strokes.
Together, the 3 signs were 100% sensitive and 96% specific for stroke, Dr. Newman-Toker reported.
In contrast, initial MRI with diffusion-weighted imaging was falsely negative for acute stroke in 12% of patients.
"Any one of these 3 oculomotor signs should prompt a more thorough workup. These patients should be presumed to have had stroke until proven otherwise," Dr. Newman-Toker said.
"Accurate bedside diagnosis of AVS is possible and could prove more cost effective than routinely obtaining neuroimaging," he concluded.
[Presentation title: Acute Vestibular Syndrome: Oculomotor Signs More Sensitive for Stroke Than MRI. Abstract M-15]
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