It’s the time of year to re-acquaint ourselves with emergency neurology. I’ve posted before on the important skill of being able to differentiate central from peripheral causes of acute vertigo, and we reviewed this in some detail at last week’s stroke conference.
By coincidence, this week’s issue of the green journal has updated information from the folks who brought us the 3 HINTS to identifying patients whose acute vertigo is likely to be stroke. A few things caught my eye:
- Between their original publication and now, they introduced a “HINTS plus” exam, the “plus” adding a hearing test by finger rub. Contrary to previous understanding, they found that abnormal hearing is more suggestive of a vascular mechanism (i.e., anterior inferior cerebellar or labrythine artery occlusion) then of peripheral vestibulopathy.
- Among 190 subjects with high risk acute vestibular presentations, 105 had a stroke confirmed on delayed MRI. The a priori probability of a stroke diagnosis in this population is over 50%! Note that these were “high risk” subjects defined as having not only vertigo, but also nystagmus, nausea or vomiting, head motion sensitivity, and unsteady gait, plus at least one vascular risk factor. So, they didn’t include every “dizzy” person, but neither did they confine their study to those evidencing clearly lateralizing brainstem or long tract signs.
- 60% of the infarcts were in the lateral medulla, but 2/3rds of those subjects had isolated vestibular symptoms and none had the full Wallenberg syndrome.
- HINTS plus identified 100% of small (< 10 mm on delayed MRI) infarcts, whereas the initial MRI only identified 47% of them, and only 36% of those in subjects presenting with isolated vestibular symptoms.
This is a very nice reminder of the importance of clinical evaluation and the limits of diagnostic imaging. In this particular population, it calls into question the practice of “let’s get an MRI in the ED and send them home if negative”. If the clinical evaluation suggests stroke, then appropriate measures for secondary stroke prevention must be undertaken even if the MRI is negative.