Inexpensive Eye Exam Better than MRI for Diagnosing Stroke
Although magnetic resonance imaging (MRI) is the gold standard in the diagnosis of stroke, a team of researchers have found that a simple, inexpensive one-minute eye examination was better at diagnosing stroke than the costly neuroimaging approach. The study was a collaboration between investigators from Johns Hopkins and the University of Illinois.
Severe dizziness or vertigo can be a sign of stroke, along with nausea, weakness and/or numbness on one side of the body, problems with speech, severe headache, and difficulty seeing in one or both eyes. Approximately 2.6 million emergency room visits each year are made by people who are experiencing severe dizziness or vertigo. Although most of these cases are related to an inner ear balance problem, about 4 percent are associated with stroke or transient ischemic attack (TIA), a condition that often indicates a stroke will occur in the near future.
According to the National Institute of Neurological Disorders and Stroke (NINDS), about 600,000 new strokes are reported each year in the United States. More than half of patients who experience dizziness as part of their stroke symptoms, however, do not have other stroke symptoms, which can lead to misdiagnose of their condition. It is estimated that emergency room physicians misdiagnose at least 33 percent of these cases. Yet rapid diagnosis and treatment are critical for stroke victims. An NINDS study found that some stroke patients who received treatment within three hours of the start of their symptoms were at least 30 percent more likely to recover with little or no disability after three months. Stroke is the third leading cause of death in the United States and a major cause of debilitating, long-term disability.
The current study involved 101 patients who were at high risk of stroke because of high cholesterol, high blood pressure, or other symptoms, and who had experienced severe dizziness that had lasted continuously for several hours. The researchers administered the simple eye examination at bedside in the hospital. The eye exam consists of three tests: looking for an inability to keep the eyes stable when the patient’s head is rotated rapidly to either side, checking to see if one eye is higher than the other, and looking for jerky movements by the eye as the patient follows the doctor’s finger as it moves left to right of vice versa.
Previous research has shown that people who experience a stroke have changes in their eye movements that are related to damage in the brain from the stroke. These eye changes differ from those associated with benign diseases of the ear.
All the study participants then underwent an MRI. Any patient whose eye test suggested a stroke but whose MRI did not indicate one underwent a repeat scan. A total of 69 patients were diagnosed with stroke, 25 had inner-ear problems, and the rest had other neurological conditions. When considering only the simple eye exam, the researchers had correctly diagnosed 100 percent of the strokes and 24 of the 25 inner-ear conditions. Initial MRI scans, however, gave false negative results for eight of the 69 stroke patients, who were diagnosed correctly after undergoing a follow-up MRI.
Although further research is needed to verify the accuracy of the simple eye exam for diagnosing stroke, the study’s authors noted that if their results prove to be true, physicians could have a simple and inexpensive diagnostic option to the more time-consuming and expensive (approximately $1000 or more) MRI. With all the talk about how to save money in our overburdened health care system, such a simple eye exam would be a welcome addition.
Kattah JC et al. Stroke 2009 September 17, online
National Institute of Neurological Disorders and Stroke
Written by Deborah Mitchell
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