The bottom-line question is:
Is the cause peripheral or central in etiology?
In this great 2011 systematic review article in CMAJ on Acute Vestibular Syndrome (AVS), the authors review how (un)predictive elements of the history and physical exam are. By definition of AVS, symptoms must be continuous for at least 24 hours and have no focal neurologic deficits.
Frighteningly, the authors report many of the signs and symptoms (type of dizziness, hearing loss, patterns of nystagmus, Hallpike-Dix) are not as predictive as we classically are taught!
The take home point is to learn and incorporate the 3-part HINTS exam into your diagnostic approach (see bottom box on card). It is reported to be as good as a diffusion-weighted MRI for diagnosing a posterior stroke. The steps are:
- Do the horizontal head impulse test. (Normal = central cause)
- Check for directionally-alternating nystagmus movement on left and right gaze.
- Do the alternate cover test.
The following is a hepful 10-minute video showing normal and abnormal HINT findings:
- Head impulse testing
- Nystagmus testing
- Testing of skew
From Dr. Scott Weingart's video supplement to his EMCrit podcast on posterior strokes.
Thanks to Dr. Brian Resler (UCSF-SFGH EM resident) for giving me the heads up about this at Followup Conference!
Reference
Tarnutzer AA, Berkowitz AL, Robinson KA, Hsieh YH, Newman-Toker DE. Does my dizzy patient have a stroke? A systematic review of bedside diagnosis in acute vestibular syndrome. CMAJ. 2011 Jun 14;183(9):E571-92. Pubmed
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