Missed Stroke in Patients With Vertigo: A Rare Event?

January 27, 2016

The frequency of early stroke after discharge from an emergency department (ED) with a diagnosis of a peripheral vestibular disorder is "extremely low," a new study led by an ED physician concludes.

But an accompanying editorial by a neurologist argues that the relative risk for stroke in these patients is actually very high and constitutes a major public health problem. "The time for debate has passed. It is now time for action," the editorial concludes.

The study, published in the January issue of the Annals of Neurology, was conducted by a team led by Clare L. Atzema, MD, MSc, University of Toronto, Ontario, Canada.

She explained to Medscape Medical News that vertigo is a very common presentation in the ED.

"We see thousands of patients with vertigo — the vast majority of them have nothing seriously wrong with them, but we wanted to investigate how many of these patients have stroke that we are missing."

For this study, the researchers used diagnostic codes to identify all patients in Ontario who had come into an ED with vertigo and been sent home with a primary diagnosis of a peripheral vestibular disorder. They assessed hospitalized strokes at 7, 30, 90, and 365 days, as well as subsequent falls, motor vehicle accidents, fractures, and burns. To provide context, they assessed the same outcomes in propensity score-matched discharged ER patients with renal colic.

Results showed that among 41,794 patients, 76 (0.18%) had a stroke within 30 days. Accidental injury at 30 days ranged from 0.01% (falls) to 0.15% (fractures).

The relative risk for 30-day stroke was 9.3 times higher than among matched renal colic controls. This relative risk was highest at 7 days (50-fold) and diminished with time since ED visit: to 6-fold at 90 days and 2.5-fold at 1 year. There was no difference in the risk for accidental injury.

"We found that only a very small proportion — around 0.2% — of these patients go on to have a stroke within the next month," Dr Atzema commented. "So emergency physicians can be reassured by these findings when discharging a patient they are confident has a diagnosis of peripheral vertigo."

She said that this brings up the question of what to do about the few stroke patients who are missed.

"Should we be doing more to identify these patients? We can't possibly subject all patients with vertigo to an MRI scan - if we did this the whole hospital system would collapse. It may be possible to do a CT [computed tomography] scan, but this doesn't tell you much about whether a patient is going to have a stroke or if they have had a stroke in the cerebellum — the part of the brain associated with dizziness."

She added: "How much are we going to do to try and identify these very few patients?"

More Must Be Done

But in his editorial, David E. Newman-Toker, MD, PhD, Johns Hopkins University School of Medicine, Baltimore, Maryland, argues that more does indeed need to be done.

He points out that vertigo and dizziness are responsible for an estimated 4.4 million ED visits in the United States each year, and roughly 3% to 5% of these will be strokes.

He says the ED physicians have a difficult job identifying the stroke patients because vertigo is the most common symptom of posterior circulation ischemic strokes and is frequently unaccompanied by more obvious neurologic symptoms.

Dr Newman-Toker maintains that of the 130,000 to 220,000 strokes and transient ischemic attacks presenting vestibular symptoms to US EDs each year, an estimated 45,000 to 75,000 are missed.

"The present study found that patients discharged from the ED with peripheral vestibular diagnoses are at 50-fold increased risk of stroke in the 7 days postdischarge relative to propensity-score–matched controls. These numbers suggest that our current diagnostic practices are largely ineffective and there is substantial room for improvement," he writes.

He notes that assessing three vestibular eye movements (with the Head-impulse-nystagmus-test-of-skew [HINTS] test) can identify stroke patients and that video-oculography technologies in development may make these specialized examinations routinely available. He claims that such tests "could prevent disability or death for thousands."

Dr Atzema responded to Medscape Medical News: "The editorial is written from the perspective of a neurologist. I am an emergency department physician and we have different perspectives. He is suggesting the HINTS test — which he helped develop — may be the way forward, and it may well be."

She pointed out that the HINTS test has so far only been validated in a much higher-risk population, in which most of the patients turned out to have had a stroke. "But in the ED we see a much lower risk population. We don't know if the HINTS tests would pick out the missed stroke patients in this population."

She added, however, that "if it did work, then that would be fantastic and I suppose there is no harm in doing it. So it is a reasonable thing to do."

Ann Neurol. 2016;79:32-41. Abstract Editorial


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