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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Best PV card yet!
ReplyDeleteGreat card! I would only add that the head impulse maneuver should be performed as the last test since it might falsely alter the readings of the other two. The sequence therefore should be: nystagmus evaluation, test of skew and finally the horizontal head impulse test.
ReplyDelete@Scott: Thanks for the idea! I found this article from your LifeInTheFastLane article listing.
ReplyDelete@Mattia Quarta: Excellent tip. I haven't tried this yet but will definitely follow your suggestion. Sounds like you have lots of experience with this. Also it seems that the horizontal head impulse test probably would cause the most amount of dizziness/nausea, and it makes sense to save this as the last of 3 maneuvers.
I cannot claim to be an expert, yet I had been using the HINTS battery sistematically in the last year and a half. It is a very useful tool and the interesting thing is that it works pretty decently even in the hands of an non expert like me. The head impulse test is eventually the annoying part but it rarely ends up with the patient puking all over the ED. Nonetheless I generally tend to persuade the patient that a bit of suffering is worth the go because it will for sure shorten the time spent in the ED and will more propably let us reach a diagnosis. Two tricks that I've learned so far with the head impulse test: be very concentrated during the examination since refixation can be subtle (whenever possible I take a short clip with my mobile phone and watch carefully the test afterwards); performing the thrust towards the midline after having rotated gradually the head to one side allows a better perception of the saccade refixation movement since at the end of the impulse the eyes are in the frontal plane (the test has originally been developed performing the thrust from the midline towards one side but I doubt that this variation invalidates the test since its principles are preserved). One more thing: perform the thrust changing the side of the impulse randomly otherwise the patient will be able to predict the direction of the movement and compensate making the test falsely normal.
ReplyDeleteWow, Mattia. This detailed insight into the head impulse test is much appreciated. I saw on Scott Weingart's website about video-ing eye movement and using a slow motion app to help you identify subtle saccadic reflex movement of the eyes. Thanks!
ReplyDeleteGlad to be useful! I visited Scott Weingart's website as you suggested and even bought the app! Thanks
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