Vertigo and dizziness account for 4 million ED visits per year in the United States, about 5% of which are attributable to stroke. Some patients present to the ED with acute vestibular syndrome (AVS), a condition that involves severe, continuous vertigo or dizziness, nausea or vomiting, gait instability, head motion intolerance, and nystagmus that can last from days to weeks. While most AVS cases have benign causes (vestibular neuritis or labyrinthitis), about 25% are caused from the brain stem or cerebellar strokes.
“Distinguishing strokes causing AVS can be challenging for ED physicians because signs and symptoms mirror benign conditions,” says David E. Newman-Toker, MD. CT and MRI with diffusion-weighted imaging are typically used to detect stroke, but these tests still miss a large number of strokes within 48 hours of symptom onset.
Eye Movements Matter
Studies have shown that bedside eye movement findings can help differentiate causes of AVS as being either stroke or a benign inner ear lesion. Eye movement tests can be applied rapidly and are noninvasive, but they are unfamiliar to most non-specialists. Recently, an easy-to-use video-oculography device that is lightweight, portable, and noninvasive has been developed. It has been shown to accurately measure the key eye movements under controlled laboratory conditions.
“If video-oculography can work similarly in clinical practice, it could lead to earlier stroke diagnoses and more efficient ED testing and triage decisions for patients with acute vertigo and dizziness,” says Dr. Newman-Toker. “Fully automating the device for use in EDs might eventually mean the technology can be used without onsite expertise. Such an approach would be analogous to diagnosing a heart attack by electrocardiography in patients with high-risk chest pain.”
Promising Early Results
In a recent issue of Stroke, Dr. Newman-Toker and colleagues published a proof-of-concept diagnostic accuracy study that sought to determine whether video oculography could help discriminate stroke or vestibular neuritis in 12 consecutive ED patients with AVS. The device recorded eye movements, including quantitative horizontal head impulse testing of vestibulo-ocular-reflex function. In all 12 study patients, the device was 100% accurate for predicting stroke versus vestibular neuritis as AVS causes. The authors have since tested the device on 14 more AVS patients, finding the same results (100% accuracy), according to Dr. Newman-Toker.
“Our data suggest that a portable video-oculography device could someday be used in EDs to help non-specialists diagnose stroke in patients with acute vertigo or dizziness,” Dr. Newman-Toker says. “The device was well tolerated by patients, and it was not hard to train technicians to perform the test and operate the device. Video oculography could help fulfill a critical need for diagnosing patients with acute vertigo or dizziness at high risk for stroke in a timely, accurate, and efficient manner. As we gather more information on the accuracy, value, and cost-effectiveness of this diagnostic method, it’s hoped that we can find the best way to integrate this technology and improve patient outcomes.”
Readings & Resources (click to view)
Newman-Toker DE, Tehrani AS, Mantokoudis G, et al. Quantitative video-oculography to help diagnose stroke in acute vertigo and dizziness: toward an ECG for the eyes. Stroke. 2013;44:1158-1161. Available at: http://stroke.ahajournals.org/content/44/4/1158.abstract.
Newman-Toker DE, Hsieh YH, Camargo CA Jr, Pelletier AJ, Butchy GT, Edlow JA. Spectrum of dizziness visits to US emergency departments: cross-sectional analysis from a nationally representative sample. Mayo Clin Proc. 2008;83:765-775.
Tarnutzer AA, Berkowitz AL, Robinson KA, Hsieh YH, Newman- Toker DE. Does my dizzy patient have a stroke? A systematic review of bedside diagnosis in acute vestibular syndrome. CMAJ. 2011;183:E571-E592.
Kattah JC, Talkad AV, Wang DZ, Hsieh YH, Newman-Toker DE. HINTS to diagnose stroke in the acute vestibular syndrome: three-step bedside oculomotor examination more sensitive than early MRI diffusion-weighted imaging. Stroke. 2009;40:3504-3510.
Weber KP, Aw ST, Todd MJ, McGarvie LA, Curthoys IS, Halmagyi GM. Head impulse test in unilateral vestibular loss: vestibulo-ocular reflex and catch-up saccades. Neurology. 2008;70:454-463.
MacDougall HG, Weber KP, McGarvie LA, Halmagyi GM, Curthoys IS. The video head impulse test: diagnostic accuracy in peripheral vestibulopathy. Neurology. 2009;73:1134-1141.