Stroke: For some presentations, eye exam better than MRI in diagnosing stroke
 |
David E. Newman-Toker, MD, PhD, assistant professor of neurology at the Johns Hopkins University School of Medicine in Baltimore and colleagues, studied 101 patients who were already at higher than normal risk of stroke because of factors including high blood pressure or high cholesterol.
The researchers found that quick examination caught more strokes than MRI, suggesting that physicians could have a way of improving care, while avoiding the costly use of MRI.
"The idea that a bedside exam could outperform a modern neuroimaging test such as MRI is something that most people had given up for dead, but we've shown it's possible," said Newman-Toker.
Dizziness is responsible for 2.6 million emergency room visits a year in the U.S. While most are caused by conditions such as inner ear balance problems, about four percent are, according to the authors, signals of stroke or transient ischemic attack.
More than half of patients with dizziness who experience stroke do not show classic stroke systems such as numbness or speech problems, so it is estimated that emergency room physicians misdiagnose at least a third of those patients.
"We know that time is brain, so when patients having a stroke are sent home erroneously, the consequences can be really serious, including death or permanent disability," said Jorge C. Kattah, MD, chairman of neurology at OSF St. Francis Medical Center in Peoria, Ill., who co-led the study.
Previous research showed that people experiencing a stroke have eye-movement alterations that correlate with stroke-damage to various brain areas and that these are distinct from eye-movement alterations seen with benign ear diseases. The researchers wanted to find out whether testing eye movements in patients complaining of dizziness could help them determine which patients were suffering a stroke and which had other problems.
The patients in the study were chosen after they had complained of severe dizziness that lasted several hours. The researchers gave each patient an exam consisting of three eye-movement tests—one testing for inability to keep the eyes stable as patients' heads were rotated rapidly to either side; one looking for jerkiness as patients tracked a doctor's finger to look right and left; and one checking eye position to see if one eye was higher than the other. The patients then received MRI exams to confirm stroke.
Sixty-nine patients were diagnosed with stroke and 25 with inner-ear conditions. The remainder had other neurological problems. Using the three eye-movement tests, the researchers correctly diagnosed all of the strokes and 24 of 25 with inner-ear conditions. By contrast, initial MRI scans were falsely negative in eight of the 69 stroke patients, who were later correctly diagnosed with follow-up MRI exams.