Normal head impulse test differentiates acute cerebellar strokes from vestibular neuritis.
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.
Newman-Toker
David E
DE
Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Kattah
Jorge C
JC
Alvernia
Jorge E
JE
Wang
David Z
DZ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002526:Cerebellar Diseases / Q000150:complications / Q000175:diagnosis*; D002531:Cerebellum / Q000098:blood supply; D003430:Cross-Sectional Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010808:Physical Examination; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012027:Reflex, Vestibulo-Ocular; D020521:Stroke / Q000150:complications / Q000175:diagnosis*; D020338:Vestibular Neuronitis / Q000150:complications / Q000175:diagnosis*