This is the final installment of this series regarding my “faux” Clinical Practice Guideline (CPG) for Acute Vertigo.
Clinicians should use the HINTS protocol for increased efficiency in evaluating patients presenting with acute vertigo.
The HINTS protocol is a series of tests that have been developed, researched and is in the gradual process of being applied as a screening tool for patients presenting with acute vertigo. I have described this protocol in detail in an earlier blog, but I will review some more recent findings to wrap up this series.
Briefly, The HINTS protocol includes a quick examination including Head Impulse testing (HI), examination for Nystagmus (N), and an exam for ocular misalignment, also known as Test of Skew Deviation (TS). This protocol has been found to be the quickest, safest, most sensitive and cost effective method to identify whether a patient with acute vertigo may be having a stroke.
In one of the early reports regarding HINTS, in 2009, Kattah and colleagues reported
“The presence of normal horizontal head impulse test, direction-changing nystagmus in eccentric gaze, or skew deviation (vertical ocular misalignment) was 100% sensitive and 96% specific for stroke. “
The take home message is that MRI missed 12% of strokes and HINTS did not miss any. Are these findings reproducible? How reliable is it to separate stroke from acute vestibular crisis?
In 2013, Newman Toker and colleagues applied the HINTS protocol to a small group (only 12 patients), but were able to identify those with stroke with 100% accuracy. In a larger group, also led by Dr. Newman Toker, the HINTS protocol was able to detect stroke with sensitivity of 96.5%, and specificity of 84.4%
In 2014, a study out of Spain applied the HINTS protocol to a small group of patients ultimately determined to have suffered a stroke. The HINTS protocol was considered abnormal in seven of eight patients with one stroke patient having a normal HINTS exam.
“Altogether 91 patients were examined, with a mean age of 55.8 years. A cerebrovascular accident was observed in eight cases. Of these (mean age: 71 years), in seven of them there were alterations in some of the HINTS signs, and in one case the study was normal (sensitivity: 0.88; specificity: 0.96). All of them had some vascular risk factor.”
Are there any dissenters?
While acknowledging the accuracy and potential benefit of using the HINTS protocol as a screening tool for stroke, some in the area of Emergency Medicine feel that studies using more representative samples of the typical dizzy patient are needed.
There is a precedent for creating a clinical decision rule to help ED Physicians determine when to order a CT scan of the head, but it applies only to blunt head trauma. The HINTS protocol holds great promise as a method to transform the initial screening of patients with acute vertigo. It has the potential to save lives and health care dollars at the same time. It will be interesting to see if something with such great potential benefit is embraced by the medical community.
Photo courtesy of spellenrijk.nl