Diagnostic Accuracy of the HINTS Exam in an Emergency Department: A Retrospective Chart Review
Written by: Eugene W. Borst, MD, MPH; Edited by: Brian Smith, DO, MA, MMsc-Med
Background:
Dizziness is a common Emergency Department presentation comprising between 1% to 3% of all ED visits annually. Prior studies have shown that when utilized by a trained physician, the HINTS exam has excellent diagnostic accuracy for diagnosing central nervous system pathologies with a greater sensitivity and specificity than MRI. This is an important concept since up to one-third of cerebellar and brainstem strokes are missed on initial assessment. Therefore, the HINTS exam is a useful tool in helping to differentiate between peripheral causes for dizziness from central causes when patients present with symptoms of Acute Vestibular Syndrome (AVS).
The Study:
This study aimed to understand if the sensitivity and specificity of the HINTS exam was the same when utilized by emergency physicians in the emergency department, and to better understand the frequency of its use and the characteristics of the patients that received the exam.
It was designed as a retrospective chart review at a tertiary care ED in Ontario, Canada, between 2014 and 2018. Charts were reviewed based on triage diagnosis. Those that were included had a diagnosis of dizziness, vertigo, light-headedness, and/or unsteadiness (exclusion criteria found with the table below).
Primary outcome: Diagnostic Accuracy of the HINTS exam (those who had a “central” result for their exam and were diagnosed with a Central Nervous System (CNS) cause for their dizziness).
Secondary outcomes:
The number of patients that were appropriate for a HINTS exam (symptoms of AVS) and received one
The number of HINTS exams performed on inappropriate candidates
The number of patients that received both a HINTS exam and Dix-Hallpike test for BPPV (nonoverlapping patient populations)
Symptoms for AVS on chart review were approximated based on these three criteria:
Documentation of both Nystagmus and unsteady gait
Symptom timing was acute and was persistent/ongoing at the time of examination. If timing was not documented, it was assumed that symptoms were continuous and an analysis was run twice, with and without this population, to assess for sensitivity and specificity with strider and less strict criteria
Focal neurologic deficits consistent with central causes for vertigo (the literature is mixed regarding the utility of the HINTS exam in patients that have obvious neurologic deficits on exam pointing to a central cause)
Important to note is that the presence of Nystagmus is generally regarded as the defining indication to perform the HINTS exam.
HINTS results should also be documented as “central” or “peripheral”. They are never truly “positive” or “negative” because that is not the diagnostic purpose of the test. It is meant to either point to a central or peripheral cause of dizziness.
Results:
A total of 2,309 patients met the inclusion criteria for the study. Of those, 450 patients (19.5%) received all or part of the HINTS exam. Strikingly, 96.5% of those patients that received a HINTS exam did not meet the diagnostic criteria for receiving one. This was largely because either the symptoms were documented as being intermittent, or there was no documented presence of nystagmus. Only 6 patients in the study had a diagnosis of central cause for their dizziness, but none of those patients received the HINTS exam. Lastly, 49% of patients that received the HINTS exam also received the Dix-Hallpike exam.
Conclusion:
The HINTS Exam has limited utility in the Emergency Department. This study showed that the exam was often used incorrectly and on patients that did not meet criteria for the HINT exam. Based on the result of the study the investigators could not properly identify the sensitivity and specificity of the HINTS exam in the ED. ED physicians should undergo further training to identify proper candidates and to be able to interpret exam results.