My most recent blog discussed the state (or lack thereof) of the development of a Clinical Practice Guideline (CPG) for acute vertigo. I ended the blog with the following thought:
“Is it possible that a Clinical Practice Guideline for acute vertigo could result in more accurate diagnosis and more effective treatment, while at the same time dramatically reducing cost? There is only one way to find out.”
Earlier this year, a group out of Australia published the results of a study examining the impact of having trained clinicians, with the right equipment, doing the right exams, in the emergency department when a patient arrived with the complaint of vertigo. There were some expected and some unexpected results.
First, in their introduction, they note that “up to 55% of ER presentations receive no aetiological diagnosis and 20-35% an incorrect diagnosis”. Even with my limited math skills, that equates to a correct diagnosis rate of between 10% and 25%.
Can we not do better? Yes, we can. And they did.
Protocol for Patients with Acute Vertigo
The protocol used for acute vertigo involved a structured history and HINTS exam, viewing for nystagmus using infrared video-oculography, and video head impulse test (vHIT). They referred to this approach as a “Quantitative HINTS plus. The plus being positional testing in those with episodic vertigo. They also performed audiometry in those complaining of hearing changes.
In this study 148 patients were categorized as acute vestibular syndrome. This is the group of patients which would/should be addressed in a clinical practice guideline for acute vertigo. Of the 148 patient’s, 61 (41.3%) were diagnosed with vestibular neuritis and 46 (31.1%) were diagnosed with stroke. Of the 46 diagnosed with stroke, 38 had evidence of infarction on neuro imaging, either CT or MRI.
Again, utilizing my limited math skills, this looks like neuro imaging had an 82% yield in confirming stroke compared with historical yield of 1 to 12% reported in earlier studies of patients presenting with acute vertigo but not undergoing any type of preliminary structured screening.
This means that imaging was not required, therefore not performed, on 41% of patients presenting with acute vertigo. Stroke was separated from Vestibular Neuritis with 90% sensitivity and 92% specificity prior to imaging by using the clinical HINTS exam.
A number of things stand out from these findings. First is the increased yield of neuro imaging in selected patients, dramatically increasing the sensitivity of neuro imaging for posterior fossa stroke as compared to numbers reported in previous studies. Second is the higher percentage of stroke as compared to vestibular neuritis in patients with AVS, possibly explained by previous reports that many posterior fossa strokes are historically missed on initial presentation.
Third is the fact that this approach does not cost more money but actually saves money by eliminating much unnecessary imaging.
This blog only covers one aspect of this excellent study. Common vestibular conditions such as BPPV and migraine were also detected at a higher rate using this protocol.
So, rather than just speculate on the potential benefits of a clinical practice guideline for acute vertigo, this group has given us some evidence that modernizing our approach and equipping our emergency departments do, in fact, reduce cost and improve patient care.