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Breaking News: Study Throws More Weight Behind HINTS

Shaw, Gina

doi: 10.1097/01.EEM.0000455716.46514.d4
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When David Newman-Toker, MD, PhD, was a neurology resident at Massachusetts General Hospital in the mid-1990s, the hospital did not yet have an emergency medicine residency, so neurology residents served as one of the ED's primary triage services. “Patients were sent directly to us by the nurses if they had dizziness or headaches or back pain,” said Dr. Newman-Toker, now an associate professor of neurology at the Johns Hopkins University School of Medicine.

Many times, he said, patients complaining of dizziness would be referred to him after they had already been misdiagnosed at other hospitals. “I still recall a ceiling painter in his 50s who went to another local ED after waking up very dizzy and a little bit hoarse. They diagnosed labyrinthitis to explain the dizziness. Seeing that his throat was red, they diagnosed him with pharyngitis, too. They told him it was all just a viral syndrome and sent him home,” Dr. Newman-Toker recalled.

The next day, the patient's wife brought him back, insisting that something more must be wrong. The primary care doctors at the hospital continued to insist that the man had labyrinthitis, but finally, under protest, admitted him to the hospital. He was sent to Mass General for a laryngoscopy to assess his hoarseness, and Dr. Newman-Toker more thoroughly examined the patient and recognized that his symptoms were actually due to stroke. “He had multiple posterior circulation strokes from a vertebral artery dissection. He was lucky to recover well, but he could have stroked out his entire brainstem during the diagnostic delay,” he said.

That was 15 years ago, but even now, many of the four million people who present to emergency departments with dizziness each year are still frequently being misdiagnosed and mismanaged, Dr. Newman-Toker said.

“Acute dizziness is frequently a benign condition, but probably 15 to 25 percent of the time, it's due to something dangerous,” he said. “But the underlying causes in those cases are so diverse that no one of them accounts for more than five percent of cases. Stroke is the most common dangerous cause of dizziness that is frequently missed. I would say that probably half of strokes in which the patient presents only with isolated dizziness or vertigo are misdiagnosed initially.”

The challenge: a rapid, accurate means of distinguishing benign patients from those who are likely to be having a stroke or other cerebrovascular event. Emergency physicians have been trained for four decades to use the type of dizziness to define which disease the patient is most likely experiencing:

  • Vertigo: “It feels like I'm spinning.”
  • Presyncope: “I feel like I'm going to faint.”
  • Disequilibrium or unsteadiness: “I feel like I'm going to fall over.”

But many patients aren't always clear about the type of dizziness they're experiencing; they may also describe more than one type or the type may change from episode to episode.

Instead, Dr. Newman-Toker said, a more reliable diagnostic method involves focusing on timing and triggers rather than type, distinguishing transient from persistent dizziness (most stroke patients have persistent symptoms) and then applying a three-step eye movement test called HINTS to all patients with persistent, continuous symptoms.

The exam includes:

  • Head Impulse (right and left).
  • Nystagmus Type (gaze testing).
  • Test of Skew (alternate cover test).

HINTS takes about two minutes to perform, and can predict stroke with high accuracy, Dr. Newman-Toker said. “It requires special skills that are not currently available in most EDs, but a new FDA-approved video-oculography device, which can be operated by a technician, objectively records these eye movements, and has recently been shown in a small prospective study to distinguish stroke from vestibular neuritis in the ED.” (Stroke 2013;44[4]:1158.)

Dr. Newman-Toker and colleagues found that HINTS outperforms the ABCD2 risk stratification rule in stroke screening for dizzy patients, with sensitivity of 96.5% and specificity of 84.4% for HINTS vs. 61.1% and 62.3% for ABCD2, according to their Academic Emergency Medicine study. (2013;20[10]:987.)

Jonathan Edlow, MD, a professor of emergency medicine at Harvard Medical School and the vice chair of emergency medicine at Boston's Beth Israel Deaconess Medical Center, agreed in an accompanying editorial that the timing and triggers of the dizziness should direct the evaluation, not the type of dizziness. “Doctors tend to lump all vertigo and dizziness together when it is really the time course and triggers of the symptoms that help you tease out different disorders. A patient with BPPV and a patient with a cerebellar stroke may both say that the room is spinning, but the approach to diagnosis and treatment is drastically different. The problem is that we've been teaching the wrong paradigm.”

HINTS is not applicable to all dizzy patients, Dr. Edlow said, but it should only be used for the group of patients whose dizziness falls into the category of acute vestibular syndrome. “Otherwise, you will obtain misleading information. If it's performed on a patient with dizziness due to dehydration or benzodiazepine use, or even fever and appendicitis, the HINTS exam (specifically, the head impulse test) would probably show findings that are worrisome for stroke,” he said.

Dr. Edlow proposed a new timing and triggers paradigm for dizzy patients, which he calls ATTEST:

A: Associated symptoms. Determine any other chief complaints or abnormal vital signs pointing toward a particular diagnosis, such as fever or cough.

TT: Timing and Triggers. Using history, define timing and triggers just as with a patient presenting with chest pain.

ES: Exam Signs. Use the physical examination, including a neurologic examination with the HINTS exam, to try to clarify the diagnosis.

T: Testing. If diagnostic ambiguity persists, other tests will be necessary, such as ruling out a pulmonary embolism or a cerebellar stroke.

“CT is a poor tool in diagnosing stroke, especially for early strokes and especially for those in the posterior circulation,” Dr. Edlow said.

And yet, said Dr. Newman-Toker, it's used up to half of the time to help rule out stroke in patients with dizziness. MRI is a superior test for posterior circulation stroke, but it is expensive and not always available, and it, too, misses posterior circulation stroke as much as 12 percent of the time in the first 48 hours. “We can deploy MRI more effectively if we target the right patients,” Dr. Newman-Toker said.

HINTS is now being taught more frequently among neurology residents in academic medical centers, something that wasn't the case just a few years ago. “But in the ED, it's only used by very early adopters,” Dr. Newman-Toker said. “In the emergency room, when you have people bleeding out and arresting and not breathing, it may seem like a foreign notion to spend time dealing with the minutiae of eye movements. It sounds like something a specialist should labor over. But there are just not enough specialists — even general neurologists — to go around and see all the dizzy patients. This needs to be something that ED physicians embrace.”

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