New study: CT a poor tool for patients presenting with dizziness
October 1, 2013
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New study: CT a poor tool for patients presenting with dizziness
Experts urge providers to become adept at using clinical skill, bedside assessment
Executive Summary
A new study notes that dizziness accounted for roughly 4% of ED visits in 2011, and that patients seeking emergency care for the condition are on the increase. However, investigators point out that too often such patients receive expensive CT scans to rule out strokes even though CT not a good tool for this purpose. Experts say a bedside assessment that focuses on eye movements can do a better job of distinguishing between patients who are having strokes and those who have a benign form of dizziness, but the assessment requires clinical skill to perform with confidence. Nonetheless, some experts believe that the assessment will become a standard of care in the diagnosis of patients who present with dizziness within five years.
• Investigators project that costs associated with ED visits for dizziness will reach $4.4 billion by 2015, with much of this cost coming from expensive imaging tests that provide little value.
• Data show that the use of imaging tests on patients who present with dizziness has quadrupled since 1995.
• Experts say few physicians realize that CT scans miss more than 80% of strokes in the early stages.
• The horizontal head impulse test is a bedside exam that is highly accurate at predicting stroke, and could save $1 billion per year if skillfully performed on a large scale in busy EDs, say experts.
Patients presenting with complaints of dizziness or vertigo are a common occurrence in the ED. An analysis of data extracted from two large, national databases suggests that these types of visits accounted for about 4% of all ED visits, at an estimated cost of more than $3.9 billion in 2011, with costs projected to reach $4.4 billion by 2015.1 However, researchers from Johns Hopkins University School of Medicine in Baltimore, MD, note that much of this cost is for computed tomography (CT) studies that providers use to rule out strokes and other conditions in these patients, even though such tests have been shown to provide little value in ruling out ischemic stroke, the most common type of stroke.
David Newman-Toker, MD, PhD, an associate professor of neurology at Johns Hopkins and a co-author of the new study published in Academic Emergency Medicine, suggests that there are undoubtedly numerous reasons why emergency physicians opt for CT in these cases, but lack of awareness probably heads the list. "All of them know that MRI [magnetic resonance imaging] would be better, but I think very few of them know that CTs at this early stage miss more than 80% of strokes," he explains.
While lack of access to MRI may be a factor in some cases, Newman-Toker notes that fear of litigation probably plays a role in driving the use of CT in these cases as well. "A neuro image is something clinicians can tangibly point to and say that they did a scan, they looked, and a radiologist told them that there was no stroke, so they sent the patient home. This is a strong defense in a medical legal case," he says. "However, increasingly this will not be the case as people become more aware of just how useless CT scans are for this particular problem."
Rather than turning to expensive imaging tests in all these cases, Newman-Toker suggests there is a better way to accurately distinguish between patients who are suffering from stroke and patients who are experiencing a benign form of dizziness. In fact, he says that if emergency physicians became proficient in the use of a simple bedside exam, called the horizontal head impulse test, the health care system could save as much as $1 billion per year while also improving care quality in these cases.
Experts: Don't rely on CT
In their study, which noted the rising annual costs associated with dizziness presentations in the ED, investigators also found that visits to the ED for dizziness-related complaints are on the rise. They discovered that while the annual number of visits to the ED for all reasons jumped by 44% between 1995 and 2011, the number of ED visits for dizziness nearly doubled during this period.
It's not clear why more people are presenting to the ED with this complaint, says Newman-Toker. "One would have thought that it might be just because of the aging population because [dizziness] is a little bit more common in the elderly, but we looked at that and didn't find that as a rationale," he explains. "It is possible that people are becoming more aware of [dizziness] as stroke symptom, and that is prompting more people to come to the ED rather than stay at home and wait it out or go to see their primary care physician (PCP)."
Investigators found that the use of imaging tests on patients who present with dizziness has quadrupled since 1995. While 10% of these patients received imaging tests in 1995, nearly 40% received such tests in 2011. Newman-Toker adds that while CT is useful in detecting hemorrhagic stroke or bleeding in the brain, this type of stroke is rarely associated with dizziness. Further, in the rare instances when these patients do experience dizziness, there are usually other defining symptoms, such as confusion or weakness, that clarify to the clinician that a CT is in order, he explains.
However, for the vast majority of strokes, Newman-Toker stresses that CT is the wrong diagnostic tool because it misses 85% of strokes in the first 24 hours after symptoms commence, and 60% of strokes after that point. When dizziness is the primary symptom of stroke, the diagnosis is missed in the ED about a third of the time often because physicians have a false sense of security from normal results on CT scans, he explains.
Pay attention to the eyes
While there is no question that MRI is the better tool for diagnosing stroke, it is much more expensive and takes much longer to complete than a CT. However, if ED physicians could rely on a bedside assessment to distinguish between the patients who may be suffering from strokes and those who have benign inner-ear disorders, the health system would still save money because only a small subset of patients who present with complaints of dizziness would need the MRIs, explains Newman-Toker.
The horizontal head impulse test is a bedside assessment that can enable clinicians to make these types of judgments, but there is little awareness of the tool in busy EDs, according to Newman-Toker. "The sixth sense is the vestibular system it is the sense of balance, and we ignore it all the time," he says. "There is a small set of people who have made this the focus of their careers. They have learned and understood things about eye movements and the balance system that most people never get exposed to in the course of their medical training."
While much of this knowledge is hyper-specialized and not particularly important for most clinicians, Newman-Toker says frontline clinicians should really learn how to conduct this one assessment because it is a very accurate predictor of stroke.
The horizontal head impulse test requires no special equipment or tools. A clinician merely asks the patient to focus on a particular spot on the wall as the clinician moves the patient's head from side to side. The clinician focuses his or her attention on the patient's eyes. If the patient is making fast, corrective eye adjustments in response to the head movements, that would indicate that the patient is experiencing a benign form of dizziness rather than a stroke.
However, Newman-Toker emphasizes that it takes practice and expert guidance to be able to perform the assessment with a high degree of confidence. "We need that kind of mentorship to really disseminate this effectively from an educational standpoint," he says. "It is too hard to read a paper and look at videos to figure out how to do this on your own to the point where you can make a high-stakes decision on whether to scan somebody or not."
Provide bedside teaching
While the horizontal head impulse test is not generally taught to medical school students, there are settings in which clinicians who are experienced in conducting the assessment are passing on the required skills to other clinicians. For instance, Jonathan Edlow, MD, FACEP, vice chairman of the Department of Emergency Medicine at Beth Israel Deaconess Medical Center (BIDMC) in Boston, MA, has been regularly using the assessment himself for four years, and he is also teaching residents and other faculty how to conduct the assessment, but that doesn't mean that the technique has become a standard of care in the ED at BIDMC.
"This sort of change in practice is not usually a revolution where one day it is not there and the next day it is there by fiat," says Edlow. Rather, he notes that it is more of a step-by-step evolution that involves convincing practitioners that the approach offers a better way of distinguishing between patients who are experiencing strokes versus patients who are experiencing a benign form of dizziness. "Increasingly, it is being done much more frequently, but it is not a standard of care. I don't think it is a standard of care in any ED," he says.
"It is an incremental thing. You can teach someone about the procedure in a lecture. I can and I do give lectures about how to do this, but you really need to give people some bedside teaching not just with patients who don't have the finding [of a potential stroke], but on someone who does," explains Edlow. "So it does take time. It is almost like winning people over one at a time."
Edlow says he has not gathered any hard data to document the effectiveness of the procedure, but he does hear from clinicians who have put the education and mentoring that he has provided into practice. "I will get an email a year later, or they will come by the office if they are still here," he says. "They will say they tried it, they like it, they use it, and it works."
Clear up misconceptions
However, while Edlow is a proponent of the approach, he is not sure that large-scale adoption of the assessment would necessarily make a huge difference in the care that patients with dizziness receive. "A relatively small number of strokes are cerebellar strokes and brain stem strokes, and many of those are going to be obvious anyway," he says. "So would [the technique] make a positive difference? Sure. Is it worth doing? Sure. But I don't know that this is going to revolutionize emergency care of stroke patients."
Edlow does acknowledge that adoption of the approach would make a meaningful dent in the overuse of CT scans for patients with dizziness. "Doctors have a reflex let's get a CT scan because this is a brain problem," he says. "And not only is it usually not helpful, but it can be harmful in the sense that intellectually people might not know of the limitations of CT. Once you have a test on the chart in your hands, there is a psychological factor where you begin to take things off the table even though you can't or you shouldn't."
Edlow also emphasizes that this is not just an emergency physician issue. "The way we have taught physicians of any specialty to deal with dizziness is, I think, flawed, and comes from work done 40-45 years ago, so I don't know that emergency physicians are that much worse than a general neurologist or a general ENT person," he says. "The reality is that general physicians, family doctors, internists, emergency physicians, and neurologists for the most part are taught that [you arrive at] this dizziness diagnosis by asking patients about the quality of their symptoms."
Edlow adds that when he sees neurology residents examine a dizzy patient, it is clear that they are laboring under the same partial misconceptions as emergency physicians. "The overarching message is that we need to really change the way we teach the diagnosis of dizzy patients to everybody so that people are thinking about it differently," he says. "CT is rarely the best first test."
Prepare for change
One tool that could help with training, or even potentially clinical decision support, is a video-oculography machine. The device, which includes goggles, a web camera, and an accelerometer, can capture the types of eye movements that can be difficult for clinicians to pick up on when assessing patients who present with dizziness. Thus far, FDA approval of the machine is limited to measurement of balance function, and not for diagnosing any particular condition, but Newman-Toker observes that this could change with more study. "Hopefully, we will be at a point in a few years where this is literally like an EKG machine," he says. "You put the goggles on the patient, you do the testing, and it gives you not a perfect answer, but an approximation of the best evidence."
In the meantime, Newman-Toker is seeking grant funding to create an infrastructure at Johns Hopkins University that is capable of providing the kind of in-depth training necessary to bring all the emergency physicians in Maryland up to speed on performing the eye movement tests. "As the culture changes and moves in this direction, and as people become more committed and convinced that this is the right approach, then more and more people will seek this out," he says.
Further, Newman-Toker is convinced that such methods will become standard practice in the not too distant future. "I don't know yet if the standard practice is going to be that we have a structured protocol for training people on how to do this the same way we have a structured protocol for training them how to do basic life support, or whether it is going to be that everybody has a set of goggles and the goggles spit out an answer for them in the same manner as an EKG machine," he says. "Either way, I think this is going to become standard practice in the next five years."
Reference
1. Tehrani A, Coughlan D, Hsieh U, Newman-Toker D, et al. Rising annual costs of dizziness presentations to US emergency departments. Acad Emerg Med. 2013;20:689-696.
Sources
• Jonathan Edlow, MD, FACEP, Vice Chairman, Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, MA E-mail: [email protected].
• David Newman-Toker, MD, PhD, Associate Professor of Neurology, Johns Hopkins University Medical School, Baltimore, MD. E-mail: [email protected].
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