HOW WAS THE STUDY DONE?

The study was performed at the University of Michigan. Between November 2009 and March 2013, Dr. Kerber et al.² assessed 272 people who complained of dizziness (people who had BPPV were excluded from the study). The doctors involved in the study were highly trained professionals. They used very specific tests to assess the person with dizziness. The doctors carefully recorded the person's medical history and performed a detailed neurologic examination. The first thing they did was calculate an ABCD² score. This score is based on the patient's Age, Blood pressure, Clinical features, Duration of complaints, and presence of Diabetes. In previous studies, a score of less than 4 meant a low risk of stroke. An ABCD² score higher than 4 predicted a high risk of stroke. Next, the doctors performed a combination of bedside tests that carefully measure eye movements. Together, these tests are called the HINTS test, which stands for Head Impulse, Nystagmus pattern, and Test of Skew.

All of the 272 people had an MRI. The MRI was done within 14 days of the onset of dizziness. An MRI provides a very detailed picture of the brain. It is often used to identify strokes. Dr. Kerber et al. used this as the “gold standard test.” In other words, they used the MRI to determine whether a stroke had occurred. They then compared the results of the bedside testing with the MRI to see how often the bedside testing predicted whether a stroke had occurred.

The doctors who performed the bedside testing did not know the results of the MRI. In other words, the doctors did not know whether the person had had a stroke when they performed the ABCD² or HINTS testing. This was important to prevent any biases from entering the study.

WHAT DID THE STUDY SHOW?

Twenty-nine people (29/272 = 10.7%) who complained of dizziness had an MRI that showed that they had had a stroke. Both the ABCD² and HINTS test results helped to predict which people were more likely to have a stroke.

WHY IS THIS IMPORTANT?

Dizziness is a common neurologic complaint. Although dizziness most often is not a serious problem, there are times when dizziness might be a sign of something more serious, like a stroke. Most people with dizziness are first evaluated by their primary care doctor. Some go to the emergency department and see an emergency medicine specialist. The tests used in this study, which can be done at the patient's bedside, could help to identify people who are more likely to have had a stroke. Those that testing identified as high risk might then go on to have more specific testing of the brain, such as an MRI. In other words, this type of testing could help doctors to better assess people with dizziness.

As with all studies, there were several limitations. First, all of the doctors (and patients) were at the University of Michigan. Second, the doctors had been specially trained in administering and interpreting these tests. The doctors were neurologists who had specialized training in stroke, neurologists who had specialized training in diseases that affect the inner ear, or doctors of emergency medicine who had specialized training in stroke. In the hands of these specialists, the results of testing were significant. It is not known whether a health care worker who did not have this training would be able to assess patients with the same accuracy.

More study is needed in this area. By better understanding bedside tests like these, doctors might be better able to quickly assess people with dizziness. Those for whom testing identifies a high risk would then be more carefully studied. If a stroke was found, treatment could be started to improve the stroke or to prevent future strokes.