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"