Friday, November 9, 2012

What To Do With The "Dizzy" Patient?

As the authors in this retrospective review state, "Vertigo/dizziness is a common and challenging problem faced by the ER physician."  And, this is obviously true.  Is it dysequilibrium?  Is it true vertigo?  Is it central or peripheral?  And, finally, "now what"?

This is a clearly pro-MRI and con-CT study which, unfortunately, leads to a massive disconnect with reality.  For most institutions, CT might be feasible, but MRI comes to town once a week for scheduled studies only.  But, in this review of 448 head CTs for dizziness, the CT picked up essentially 10 interesting findings – but 16% of the subset of follow-up MRIs performed changed the initial diagnosis.  Mostly, the missed diagnoses on CT were posterior circulation strokes and intracranial masses.  

So, essentially what they observed was more false negatives than true positives for CT.  This implies – at least in a retrospective fashion – that if your pretest probability is high enough for an intracranial process causing dizziness, the intention ought to be to conclude your investigations only with a negative MRI.  I think most folks – given infinite resources – would agree.  Otherwise, you'll need to base imaging (if any) on clinical findings and risk factors for cerebrovascular disease in an attempt to develop an estimate for their true probability.

"Utility of head CT in the evaluation of vertigo/dizziness in the emergency department"
www.ncbi.nlm.nih.gov/pubmed/22940762


2 comments:

  1. Very low quality evidence in my opinion. Particularly:
    - I don't think it is right to include patients with minor head trauma and patients with secondary neurological finding; they both belong to other clinical populations.
    - Only about 30% of patients received a verification.

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  2. Definitely low-quality, pragmatic observational data – but still a snapshot of the inadequacy of CT in the setting of substantial elevated pretest probability.

    Much of the discussion on twitter regarding this article centered on the use of the HINTS examination to detect cerebrovascular causes of "dizziness": http://stroke.ahajournals.org/content/40/11/3504.full

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