The HINTS exam, first reported in 2009, has been touted as a tool that can help us identify patients with central vertigo without the need for advanced imaging. (Stroke. 2009;40:3504; https://bit.ly/3jGxQc2.) The results of this study seemed promising at first glance, but closer examination revealed concerns about the applicability of this data to the bedside in the emergency department.
Patients were recruited who had a convincing presentation consistent with acute vestibular syndrome, a presentation with much stricter criteria than the generalized vertigo that often presents in the emergency department. The HINTS examination was performed by neuro-ophthalmologists rather than bedside emergency physicians in this study.
Despite the limitations of this initial study, the HINTS exam has found its way into various emergency medicine didactics and is increasingly used in emergency departments around the world. The HINTS exam has become a commonly used tool, but more recent publications have questioned its accuracy when used in the emergency department.
Several studies have shown that the HINTS examination is often applied to patients who have no signs or symptoms regarding an acute vestibular syndrome. The HINTS exam has little ability to provide meaningful clinical information in a patient without these signs. Dmitriew, et al., reported from a recent retrospective review that the HINTS exam was used in 19.5% of cases where a patient had dizziness. (Acad Emergency Med. 2021;28:387; https://bit.ly/3lIDTQc.)
Unfortunately, despite the widespread adoption of the HINTS exam, the authors found that 96.9% of patients who underwent the exam had no signs of nystagmus or consistent symptoms, meaning that the vast majority of patients with this cohort did not have SVA and were excluded from the studies that were used to derive and validate the HINTS review.
Selecting the right subset of patients is a key first step in using the HINTS exam, and the second major issue is that limited evidence suggests the exam can be reliably performed by physicians in emergency. Following the original Newman-Toker studies that had neuro-ophthalmologists perform the HINTS exam, subsequent studies have relied almost exclusively on physicians with specialized training. Chen, et al., relied on neurologists to perform the bedside exam in an early study of the HINTS exam. (J.Neurol. 2011;258:855.) A study by Batuecas-Caletrio, et al., found that all HINTS examinations were performed by ENT specialists. (Rev. Neurol. 2014;59:349.)
A study by Carmona, et al., had a neurologist and a resident perform all examinations. (Neurol before. 2016;7:125; https://bit.ly/3lGJbf4.) A recent meta-analysis by Ohle, et al., found only one study, by Kerber, et al., that included HINTS reviews performed by emergency physicians, but the review of this study was performed by neurologists trained in neurotology, neurologists trained in vascular neurology, or emergency physicians with postgraduate training in vascular neurology. (Neurology. 2015;85:1869; https://bit.ly/37rRbYW.)
At first glance, the HINTS exam does not appear to be a technically difficult test, but when used by physicians without specific training or additional tools, the available literature suggests that emergency physicians find it difficult to apply and interpret this test appropriately. Quimby et al. found in a study of emergency physicians that the HINTS exam, although used more frequently, was poorly documented or misinterpreted in about 46% of cases. (J Otolaryngol head and neck surgery. 2018;47:54; https://bit.ly/3ivwdyL.)
Ultimately, these issues of inappropriate patient selection and potential undertraining limit the usefulness of bedside HINTS examination. Dmitriew, et al., noted in a review of over 2300 patients that despite widespread use, although often in patients without signs of SIA, HINTS examination was unable to identify a single cases of central vertigo, leaving the authors unable to generate meaningful results. performance characteristics. (Acad Emergency Med. 2021;28:387.)
A nuanced review
A recent editorial promoting the use of the HINTS exam by Peter Johns, MD, and Robert Ohle, MD, asked, “Can an emergency physician learn to rapidly turn the head 20 degrees from midline to midline and observe the resulting eye? results?” (EPM. July 2, 2021; https://bit.ly/3fNTytH.) At first glance, it would seem that the obvious answer is yes, but the literature to date suggests that the process of learning and applying the HINTS exam correctly can be more nuanced.
Vanni, et al., found that emergency physicians were able to reliably perform various components of the HINTS test with a high degree of accuracy compared to an exam performed by a specialist audiologist with a reported sensitivity of 92 .9% and a specificity of 96.4%. with good interobserver agreement (k = 0.76). (Emerg Med Australia. 2015;27:126.)
The examination in this study was performed by five emergency physicians who had minimal prior specialist training. After completing five one-hour lectures and one hour of procedural instruction, the physicians completed 10 emergency department assessments under the supervision of a senior audiologist. More recently, Gerlier et al. found that emergency physicians without prior HINTS training were able to learn and apply the HINTS exam with a high degree of accuracy. The clinicians in the study had no prior training, and they had at least six hours of specific didactics before assessing a patient, and they used Frenzel glasses to assess patients for nystagmus, which essentially automated a key part of the HINTS exam. (Acad Emergency Med. July 10, 2021. https://bit.ly/3xwlF6z.)
Based on the available literature, we in the emergency department should view the HINTS exam with a healthy degree of skepticism. From a technical standpoint, I suspect the HINTS exam is a skill we could master. Emergency physicians appear to be able to perform and interpret the test with a high degree of accuracy in studies where they received targeted formal training or specialized tools. Studies without these specific tools and educational interventions that showed HINTS exam performance were unacceptable. To move from unacceptable to highly accurate, we need more studies to clarify the specifics of what we need as clinicians to apply and perform this test accurately.
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Dr. DeLaneyis Associate Professor and Associate Director of the Emergency Medicine Program at the University of Alabama at Birmingham. Follow him on Twitter at@mdelaneymd.