Benign Paroxysmal Positional Vertigo (BPPV) is the most common vestibular disorder and most common cause of episodic vertigo. Once identified, Canalith Repositioning procedures are very safe, fast and effective at resolving this condition. So effective, that when repositioning does not quickly relieve the symptoms, the most likely explanation is that the diagnosis is wrong, or the repositioning is being done incorrectly.
Diagnosis of BPPV can be challenging in that episodes are vertigo are not reliably triggered during the Dix-Hallpike (DH) test. A 2015 study documented 26% of active BPPV patients having a negative D-H at initial exam. My personal experience has been a bit higher than 26%.
This leads to two pertinent questions:
- Is there a way to increase the sensitivity of the DH test, and
- What do you do if you suspect BPPV but cannot trigger an episode on examination?
Different Techniques to Improve Sensitivity of Dix Hallpike
Two recent reports suggest different techniques for increasing the sensitivity of the D-H test. The first is based on the belief that a negative D-H might be the result of the otoconia being “stuck” in the canal, therefore, not moving when the patient is moved to supine. They recommended a brief period of head shake prior to performing the D-H, and triggered a positive response in 11 of 13 patients with initial negative D-H test. Compare this to a 2017 study out of Brazil reporting that simply doing a second D-H will trigger a positive response in about 40% of those initially testing negative.
The second technique, which I have been recently experimenting with and having some success, is described as the “loaded” Dix-Hallpike. This modification of the classic D-H involves having the patient tuck their chin forward 30 degrees in the plane of the posterior canal for 30 seconds prior to performing the D-H test. The authors describe the forward tilt as “facilitates otoconial migration towards the ampullated portion of the posterior canal” with the otoconia “moving a greater distance through the canal” and “potentially account for the longer duration of nystagmus, increased perceived severity of symptoms, and improved sensitivity.”
Thought Bubble: Tilting the head forward makes so much sense I am a little embarrassed I didn’t think of this years ago. I have had two patients in the past two weeks with initial negative D-H, followed by a positive D-H after using this technique. I think I will just routinely do this before every D-H test.
The “headshake” study is more difficult to understand, although it did work once out of several attempts for me. I have always believed the most likely cause of a negative D-H in a patient with active BPPV is the result of the patient fatiguing out the response as they move around prepping for and traveling to their appointment. Doing a headshake prior to performing the D-H seems counter-intuitive.
We typically ask patients to avoid head tilt for a few hours before their exam to avoid this. We put this in our instruction sheet that we send out along with the questionnaire to be filled out before their appointment. We also start our case history interview with the line. “Tell me everything, but show me nothing while we are talking. Don’t demonstrate any movements until we are ready to examine your eye movements.”
A positive positional test (Dix-Hallpike or lateral roll) makes the diagnosis of BPPV easy, so any techniques that might increase the odds of getting a positive test are worth the effort to explore.
I will be back with a response to the second question posed above.
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