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Normal head impulse test differentiates acute cerebellar strokes from vestibular neuritis

From the Department of Neurology (D.E.N.-T.), The Johns Hopkins University School of Medicine, Baltimore, MD; and Department of Neurology (J.C.K., J.E.A., D.Z.W.), The University of Illinois College of Medicine at Peoria, the Illinois Neurological Institute at OSF Saint Francis Medical Center, Peoria.

Address correspondence and reprint requests to Dr. Jorge C. Kattah, Department of Neurology, University of Illinois College of Medicine at Peoria, 530 N.E. Glen Oak Avenue, Peoria, IL 61637 kattahj{at}uic.edu

Objective: To test the diagnostic accuracy of the horizontal head impulse test (h-HIT) of vestibulo-ocular reflex (VOR) function in distinguishing acute peripheral vestibulopathy (APV) from stroke. Most patients with acute vertigo, nausea/vomiting, and unsteady gait have benign APV (vestibular neuritis or labyrinthitis) as a cause. However, some harbor life-threatening brainstem or cerebellar strokes that mimic APV. A positive h-HIT (abnormal VOR) is said to predict APV.

Methods: Cross-sectional study at an urban, academic hospital over 6 years. Consecutive acute vestibular syndrome patients at high risk for stroke underwent structured examination (including h-HIT), neuroimaging, and admission. Stroke was confirmed by neuroimaging (MRI or CT). APV was diagnosed by normal MRI and appropriate clinical evolution in follow-up.

Results: Forty-three subjects enrolled. One had an equivocal h-HIT. Patients with APV had a positive h-HIT (n = 8/8, 100%). Most patients with stroke had a negative h-HIT (n = 31/34, 91%). However, contrary to conventional wisdom, three patients with stroke (9%) demonstrated a positive h-HIT (1 vestibulocerebellar, 1 pontocerebellar, 1 pontocerebello-labyrinthine stroke).

Conclusions: Patients with lateral pontine and cerebellar strokes can have a positive horizontal head impulse test (h-HIT), so the sign’s presence cannot be solely relied upon to identify a benign pathology. Additional clinical features (e.g., directionality of nystagmus, severity of truncal instability, nature of hearing loss) must be considered in patients with acute vestibular syndrome with a positive h-HIT before a central localization can be confidently excluded. Nonetheless, the h-HIT remains a useful bedside test—in acute vestibular syndrome patients, a negative h-HIT (i.e., normal VOR) strongly suggests a central lesion with a pseudo-labyrinthine presentation.

Abbreviations: APV = acute peripheral vestibulopathy; DWI = diffusion-weighted imaging; FLAIR = fluid-attenuated inversion recovery; h-HIT = horizontal head impulse test; VOR = vestibulo-ocular reflex.

Supplemental data at www.neurology.org

*These authors contributed equally.

The preparation of this manuscript was supported partly by a National Institutes of Health grant (K23 RR17324-01, Building a New Model for Diagnosis of ED Dizzy Patients).

Disclosure: The authors report no disclosures.

Received July 17, 2007. Accepted in final form December 28, 2007.