Stroke diagnosis simplified with bedside 'EKG for the eyes'

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 - Stroke, endovascular. neuroimaging, neuro

A bedside device that can calibrate subtle eye and head movements may be key to correctly diagnosing strokes in patients who present with dizziness, nausea, nystagmus, unsteady gait and head movement intolerance. A brief report detailing the results of a small, proof of concept study at Johns Hopkins University was published online March 6 in Stroke.

In most cases, the cause of the symptoms in patients presenting with acute vestibular syndrome is benign, but in nearly one-fourth of cases the cause is cerebellum or brain stem stroke. These strokes are often misdiagnosed because emergency department (ED) clinical personnel typically lack the expertise to diagnose using bedside oculomotor tests—head impulse test, nystagmus and test of skew (HINTS)—which, although highly accurate, require the clinician to detect quick and subtle eye corrections. First-day CT and MRI are unable to diagnosis a significant percentage of such strokes.

David E. Newman-Toker, MD, PhD, of Johns Hopkins School of Medicine in Baltimore, and colleagues sought to determine whether a bedside video-oculography device (ICS Impulse, GN Otometrics) that records, measures and analyzes head and eye movements, accurately detected strokes in clinical practice. They enrolled 12 adults appearing at the ED of two tertiary care centers with continuous dizziness or vertigo lasting more than one hour plus nausea or vomiting, intolerance of head motion, or gait or balance disturbance between August 2011 and June 2012, and used the ICS Impulse device to record the patients’ vestibulo-ocular reflexes.

Two independent expert masked, neuro-otologists examined the data and rendered an opinion (bilaterally normal, unilaterally abnormal or equivocal). Stroke was diagnosed if the head impulse test was bilaterally normal. A unilaterally abnormal test, the absence of direction-changing nystagmus and skew indicated vestibular neuritis.

Stroke was confirmed via CT or MRI showing acute hemorrhage, MRI with diffusion weighted imaging (MRI/DWI) showing acute ischemic stroke any time after symptom onset, or delayed (more than 48 hours but less than seven days after symptom onset) MRI/DWI showing no acute stroke. Independent, masked neuroimaging experts made the stroke diagnosis.

Of the 12 study participants, six had strokes and six had vestibular neuritis. The experts using the HINTS data from the ICS Impulse device correctly diagnosed all 12 patients.

The researchers contended that the device has the potential to impact stroke diagnosis in the same way that EKGs have impacted diagnosis of acute MI. “Device-based identification of vertibrobasilar stroke in AVS [acute vestibular syndrome] could help fulfill a critical need for timely, accurate and efficient diagnosis in patients presenting acute vertigo or dizziness with high-risk clinical features,” they wrote. Use of the device could reduce unnecessary imaging and associated delays and costs, and the authors suggested that the device has possible application in ambulances or community health centers as part of a stroke network.

The authors conceded that the small study population limits the impact of the study, and they recommended large, comparative observational studies and randomized trials. They noted that their investigators were expert in assessing oculomotor function but ED personnel likely would require training to apply a diagnostic logarithm using device data. They also emphasized that patient selection is critical, as using the device to assess all patients with dizziness would greatly increase unnecessary imaging.

The manufacturer loaned the devices to the researchers, but the study was supported by grants from the Swiss National Science Foundation, the Agency for Healthcare Research and Quality and the National Institutes of Health.