The vast majority of presentations for “dizziness” in the Emergency Department are benign diagnoses – various dysequilibrium syndromes, vestibulitis, neuritis, and other disorders of the otologic canalicular system. But, then, some are strokes – and it’s quite challenging to balance diagnostic accuracy and MRI utilization.
This is an observational study performed at the University of Michigan evaluating patients presenting with complaint and exam findings consistent with acute dizziness – requiring either nystagmus or demonstrated gait instability. Of these patients, all underwent a standardized neurologic examination, including HINTS examination, and subsequent MRI. A stroke was the presumed diagnosis if an MRI was performed within 14 days and diagnostic of hemorrhage or acute infarction.
There were 320 patients enrolled, and 272 completed the clinical evaluation and an MRI. Overall, 29 (10.7%) of patients had positive imaging – and, unfortunately, little was strongly predictive. The few predictive features that shook out of their logistic regression model were the ABCD2 score, a positive HINTS exam, a central pattern to nystagmus, or the presence of other neurologic deficits. Those individuals hitting all the risk factors ended up with ~20% risk of stroke, while those with none were <5%. The remaining patients were simply in the intermediate risk group, reflecting the overall baseline level, and approximately one-third of the cohort fell into each category.
I do like their objective criteria for enrollment, based on a minimum of nystagmus or gait abnormality. I tend to feel many patients receive MRI for similar complaints absent any of these features. There is, unfortunately, no accounting of any general background rate of diagnosis of posterior circulation stroke at their institution, so there’s no way to estimate the miss rate or added value of their inclusion criteria. I think their general observations are fair starting points for shared decision-making, although there’s still not quite enough information here to dramatically improve imaging yield.
“Stroke risk stratification in acute dizziness presentations: A prospective imaging-based study”
http://www.ncbi.nlm.nih.gov/pubmed/26511453