Emergency Physician Monthly - by Brian Cohn, MD on March 30, 2014
"Dizziness remains one of the more challenging chief complaints encountered in the emergency department. This complaint encompasses a wide variety of symptoms, including vertigo, lightheadedness, weakness, and just plain not feeling good. Even when the symptom truly is vertigo, the diagnostic conundrum is no less daunting, as the symptom type is not a good predictor of cause. The challenge becomes differentiating benign peripheral vertigo from potentially life-threatening central vertigo, often the result of a cerebellar stroke. While a normal neurologic exam may feel reassuring to most clinicians, focal neurologic deficits are unfortunately frequently absent in cases of posterior circulation stroke. CT scan is often the initial imaging modality when stroke is being considered, but is notoriously insensitive, particularly when it comes to the posterior fossa, missing 60-90% of acute ischemic strokes in the brainstem or cerebellum. MRI with diffusion-weighted imaging, considered by many to be the “gold standard” for the diagnosis of stroke, is more reliable than CT, but is still far from perfect. Around 15-20% of patients with posterior circulation stroke will have a normal MRI in the early period. In addition, MRI is expensive, costly, and not available in most emergency departments. When posterior circulation stroke is considered in patients with vertigo, hospital admission or transfer is often required to complete the necessary work-up.
A rapid, bedside test to help differentiate central from peripheral vertigo would therefore have great value. The HINTS exam has been proposed as just such a test. HINTS stands for Head Impulse, Nystagmus, and Test of Skew, and is a three-part oculomotor test. If any portion of the test indicates a central etiology, the test is considered positive and further evaluation for stroke (or other central pathology) is warranted. The three components of the exam are as follows:
- Patients with peripheral vertigo will have abnormal (positive) head impulse testing, while patients with central vertigo typically have a normal (negative) head impulse test.
- Patients with peripheral vertigo will have unidirectional, horizontal nystagmus, while patients with central vertigo can have rotatory or vertical nystagmus, or direction-changing horizontal nystagmus.
- Alternate eye cover testing may reveal skew deviation in patients with central vertigo, and should be absent in peripheral vertigo."
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