Navigating the Complexities of Dizziness and Misdiagnosis

Date: April 12, 2023 Reference: Edlow et al.Guidelines for Reasonable and appropriate care in the emergency department 3 (GRACE-3): Acute dizziness and vertigo in the emergency department. AEM May 2023 Guest Skeptic: Dr. Jonathon Edlow has practiced emergency medicine for nearly 40 years and is a Professor of Emergency Medicine at Harvard Medical School. His academic interest is avoiding the misdiagnosis of patients with neurological emergencies.  This is an SGEM Xtra and #SGEMHOP combined. We have reviewed the previous two GRACE guidelines published by the Society for Academic Emergency Medicine (SAEM). GRACE stands for Guidelines for Reasonable and Appropriate Care in the Emergency Department. This is the third GRACE project. GRACE-1 tackled the common issue of recurrent low risk chest pain (SGEM#337). This contrasts with other guidelines that only looked at a single emergency department presentation for chest pain. And GRACE-2 was about low-risk recurrent abdominal pain (SGEM#367). Now we come to GRACE-3. This time it was not a recurrent condition like chest pain or abdominal pain but rather acute vertigo or dizziness. The objective of the GRACE-3 guideline is to provide an evidence-based framework intended to support patients, clinicians, and other health-care professionals in their decisions about the evaluation and management of adult ED patients with acute dizziness who do not have an obvious central cause with frank neurological findings or an obvious general medical one. The population covered by these guidelines are adult patients presenting to the ED with acute dizziness or vertigo of less than two weeks. Let us clarify some terms because it is often not clear when what people mean by dizziness and vertigo. I tend to describe dizziness as light-headedness, unsteadiness, motion intolerance, imbalance, floating, or a tilting sensation. Dizziness in GRACE-3 was defined as the sensation of disturbed or impaired spatial orientation without a false or distorted sense of motion (Barany Society). Vertigo in GRACE-3 was defined as the sensation of self-motion (of head or body) when no self-motion is occurring, or the sensation of distorted self-motion during an otherwise normal head movement. The problem is that research shows that patients often use multiple descriptors simultaneously or change their main descriptor if asked again less than 10 minutes later. So, although your concept is exactly what has been taught for decades, data from the last decade and a half show that it’s simply not true. The author group came up with 15 evidence-based recommendations based on the timing and triggers of the dizziness. Let’s go through those recommendations with the first one being an overarching one. 15 Recommendations from GRACE-3 Recommendation 1: Emergency clinicians should receive training in bedside physical examination techniques for patients with the AVS (HINTS) and diagnostic and therapeutic maneuvers for BPPV (Dix-Hallpike test and Epley maneuver), since untrained ED physicians do not reliably apply or accurately interpret results of this bedside eye movement examination. [Ungraded Good Practice Statement] HINTS stands for Head Impulse, Nystagmus, and Test of Skew. It was initially touted as a highly sensitive, specific marker for cerebellar stroke in the ED. However, study results have been mixed and there is ongoing debate about how to train for and utilize this examination in the acute care setting. A 2021 study [1] reported that EM physicians could be trained on the HINTS and it gave a sensitivity of 97% for central vertigo (SGEM#376). However, a SRMA [2] that included EM physicians showed less impressive results with a sensitivity of 83. The authors of the review felt the use of HINTS by EM physicians had “not been shown to be sufficiently accurate to rule out a stroke.” (SGEM#310). There is a clear disconnect between what is possible for emergency physicians to do and what we currently do in real life. It is possible that emergency physicians can learn to use these techniques (not only the HINTS exam, but also bedside maneuvers to diagnose and treat BPPV). This is consistent with my own anecdotal experience. What is equally clear is that without some sort of training or intentional activity to learn it, we do a pretty bad job in routine practice. Dr. Peter Johns has some great videos on YouTube to show clinicians how to do the HINTS exam. I don’t know this for sure, but I suspect that Peter, like me, picked this up by active learning, not by attending a training session. GRACE-3 goes on to help distinguish central from peripheral causes in patients with the acute vestibular syndrome (AVS). AVS is a clinical syndrome of acute-onset continuous dizziness lasting days to weeks and generally includes features suggestive of new, ongoing vestibular system dysfunction (e.g., nausea and vomiting, nystagmus, and postural instability). In the ED, patients are symptomatic even at rest, and exacerbation from head movement or position change is typical. This is different from episodic syndromes that can be spontaneous or triggered. Recommendation 2: In adult ED patients with AVS with nystagmus, we recommend routine use of the 3-component head impulse, nystagmus, test of skew (HINTS) exam for clinicians trained in its use* to distinguish between central (stroke) and peripheral (inner ear, usually vestibular neuritis) diagnoses. (Strong recommendation, FOR) [High certainty of evidence] This is very important. There was a large chart review of EM physicians that reported EM physicians misapplied the HINTS exam 97% of the time [3]. Recommendation 3: In adult ED patients with AVS with nystagmus, we suggest assessing hearing at the bedside by finger rub to identify new unilateral hearing loss as an additional criterion to aid in the identification of stroke, even if the 3-component HINTS exam result suggests a peripheral vestibular diagnosis. (Conditional recommendation, FOR) [Moderate certainty of evidence] Recommendation 4: In adult ED patients with AVS without nystagmus, we suggest assessing severity of gait unsteadiness to help distinguish between central (stroke) and peripheral (inner ear, usually vestibular neuritis) diagnoses. (Conditional recommendation, FOR) [Moderate certainty of evidence] This is a hugely important point. One should be very hesitant to make a diagnosis of a benign, peripheral cause of dizziness in a patient who cannot walk independently. Plus, in terms of disposition in general, it’s not a great idea to discharge someone who cannot walk (assuming they could walk before). This simple test is often admitted. Recommendation 5: In adult ED patients with AVS with or without nystagmus, we recommend against routine use of non-contrast computed tomography of the brain (CT) or (CT angiography [CTA]) to help distinguish between central (stroke) and peripheral (inner ear, usually vestibular neuritis) diagnoses. (Strong recommendation, AGAINST, see Implementation Considerations) [High certainty of evidence] That goes against the EM physician alphabet. A-B-C-T. We like to send these patients to the "donut of truth". What this recommendation says strongly is don't use these imaging modalities (CT or CTA) to distinguish between central and peripheral vertigo. CT is a horrible test in this setting. Of course, non-contrast CT is a bad test for any hyperacute stroke, but it’s even worse for posterior circulation strokes and even worse still for those posterior circulation strokes presenting as isolated dizziness. This is why we made a strong recommendation against the routine use of CT or CTA based upon high certainty of evidence. Recommendation 6: In adult ED patients with AVS with or without nystagmus, if a clinician trained in use of HINTS is available, we recommend against routine use of magnetic resonance imaging of the brain (MRI) or cerebral vasculature (MRI angiography [MRA]) as the first-line diagnostic test (prior to physical examination) to help distinguish between central (stroke) and peripheral (inner ear, usually vestibular neuritis) diagnoses. (Strong recommendation, AGAINST, see Implementation Considerations) [High certainty of evidence] The part about not getting an MRI is a little easier because in many places it can be difficult to get these on an urgent basis. The important part is to get clinicians adequately trained in the use of HINTS. Agree that it’s easier when it’s hard to get but it can be misleading if you can get it, do get an MRI and it’s normal. In the first 48 hours of an acute stroke that presents as isolated dizziness, MRI only has approximately 80% sensitivity. Recommendation 7: In adult ED patients with AVS and central or equivocal HINTS results, we recommend use of stroke protocol MRI (with diffusion-weighted images [DWI] and MRA) to further help distinguish between central (stroke) and peripheral (inner ear, usually vestibular neuritis) diagnoses. (Strong recommendation FOR, see Implementation Considerations regarding timing of MRI) [High certainty of evidence] Recommendation 8: In adult ED patients with spontaneous episodic vestibular syndrome, the writing committee believes that routine use of a detailed history and physical exam with emphasis on cranial nerves including visual fields, eye movements, limb coordination, and gait assessment helps to distinguish between central (TIA) and peripheral (vestibular migraine, Menière disease) diagnoses. [Ungraded good practice statement] This seems like a motherhood and apple pie statement. Take a good history followed by a directed physical exam. As a reminder, Spontaneous episodic vestibular syndrome (s-EVS) is a clinical syndrome of transient dizziness usually lasting minutes to hours and generally includes features suggestive of temporary, short-lived vestibular system dysfunction during attacks.