Answers

What does the CT show? The CT is normal, but it is the wrong study if you are concerned about a central cause of vertigo. A brain CT should be considered to rule out a bleed. Do not let a normal CT give you a false sense of reassurance.

What if any other evaluation should you consider before discharge home? The patient was persistently ataxic and so was admitted, and an MRI was done showing a large cerebellar stroke. This has the potential to swell and compress the 4th ventricle, causing obstructive hydrocephalus, brain herniation, and death. Fortunately, that did not occur.

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Discussion

Dizziness can be subclassified in a number of ways. The traditional way is to determine from the patient if it is more consistent with hypotension or vertigo. Patients with hypotension typically describe the feeling as light-headedness or feeling faint, and it is usually worse with standing. Vertigo is typically described as the room spinning and is worse with head motion. This traditional classification is not always useful as patients not infrequently say they have both of these feelings. A more useful classification may be to determine if the dizziness is constant or intermittent and if it is triggered or spontaneous. (See the top half of the table in the image for more information about this type of classification.) In the case presented here, the patient has non-episodic dizziness (NED), and the differential diagnosis is primarily between vestibular neuronitis (VN) and cerebellar stroke.

The proper physical exam for vertigo can be as complicated as the history. For this patient, if the diagnosis is VN one would expect unilateral beating nystagmus and an abnormal head impulse part of the HINTS exam. (See the bottom half of the table.) In a case of cerebellar stroke, one would likely note ataxia, multidirectional nystagmus, and a normal head impulse test. It is important to emphasize that the head impulse test should only be performed in patients who are still currently feeling dizzy, just as the Dix-Hallpike test should only be performed in patients who are no longer dizzy.

Table. Vertigo

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When the clinical presentation is consistent with a peripheral cause, no brain imaging is necessary, but when it is more consistent with a central cause a brain MRI should be performed. Head CT is not adequate to rule out cerebellar or brainstem strokes, as this case demonstrates. Head CT really only rules out a brain bleed and should never give the provider a false sense of security when the clinical concern was for posterior circulation stroke.

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Brady Pregerson, MD, is an emergency physician at Cedars-Sinai Medical Center in Los Angeles and at Tri-City Medical Center in Oceanside, California.

Reference

Pregerson B. Emergency Medicine1-Minute Consult Pocketbook. 5th ed. EMresource.org; 2017.