Bedside Eye Exam Outperforms MRI in Identifying Stroke

Allison Gandey

October 16, 2009

October 16, 2009 (Baltimore, Maryland) — Patients presenting with dizziness may actually be having a stroke, and investigators have discovered a bedside approach to help clinicians identify these patients. Presenting here at the 134th annual meeting of the American Neurological Association, researchers showed how they were able to outperform magnetic resonance imaging (MRI) and flag 100% of strokes.

The neurological exam is not dead.

"The neurological exam is not dead," joked presenter David Newman-Toker, MD, from Johns Hopkins University School of Medicine, Baltimore, Maryland.

"We only misclassified 1 out of 25 patients who had a vestibular disease that was a benign condition of the inner ear," he added during an interview. In contrast, 12% of patients who had a stroke identified on a later MRI had an initially false-negative result.

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Dr. David Newman-Toker shows what to look for in the eye exam.

"This study demonstrates the critical importance of function-linked tests over purely time-static anatomic tests in discerning the localization of vestibular dysfunction early in its course," session cochair Nina Schor, MD, PhD, from the University of Rochester Medical Center, New York, told Medscape Neurology. "It's so much the better that the tests described by Dr. Newman-Toker can be performed at the bedside in these often critically ill patients."

An estimated 2.6 million people go to the emergency department for dizziness each year. Of those, only about 5% will have a stroke. "It's a bit like finding a needle in a haystack," Dr. Newman-Toker noted.

Needle in a Haystack

The problem is even more challenging, he said, considering that many of these patients do not present with the neurological findings so often linked to stroke, such as weakness on one side of the body or difficulty speaking.

"Traditional neurological findings are often absent," Dr. Newman-Toker said, "and we have found that patients might instead have abnormal eye movements that are diagnostic of their strokes."

In this prospective cross-sectional study, investigators examined 101 patients at high risk for acute vestibular syndrome. They administered 3 tests checking vestibule-ocular reflex on horizontal head impulse, nystagmus, and ocular alignment during prism cross-cover. All patients underwent neuroimaging.

The researchers report that a normal head impulse test, direction-changing nystagmus, or skew deviation was highly predictive of stroke.

Oculomotor Signs More Sensitive for Stroke than MRI

Outcome Oculomotor Signs (%) Early MRI (%) P Value
Sensitivity (n = 69) 100 88 .006
Specificity (n = 25) 96 100 1.0

Investigators point to a number of limitations to their study, including the fact it was performed in a high-risk population, and the estimates of specificity are therefore less stable than the estimates of sensitivity. In addition, this was a single-center study, and one examiner who was masked only to MRI tested all patients. The researchers also selectively repeated MRI scans.

During the question period at the meeting, one attendee wanted to know whether an improperly performed head impulse test might trigger stroke. Dr. Newman-Toker said he has never heard of a reported case of this. "At no time is the neck over rotated," he said. "This is not a chiropractic head manipulation."

The bottom line, Dr. Newman-Toker said, is "When patients come in complaining of new dizziness symptoms, consider stroke as a possibility." He estimates that about 50,000 strokes go misdiagnosed a year in the United States. For about 20,000 people, he noted, this will result in disability or death.

This study was supported by grants from the National Institutes of Health and the Agency for Healthcare Research and Quality. The researchers have disclosed no relevant financial relationships.

American Neurological Association 134th Annual Meeting: Poster M15. Presented October 13, 2009.

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