Meniere’s disease (MD) is notoriously difficult to diagnose under the best of circumstances, as symptoms (tinnitus, vertigo and hearing loss) are transient. Vestibular tests and audiograms may be normal in the early stages. Caloric responses may be decreased or increased relative to the healthy ear depending on how recently the patient had an episode.
Because testing often fails to produce a firm diagnosis, the criteria developed by consensus opinion through the Barany Society for “Definite Meniere’s disease” is largely based on symptoms. Sometimes the circumstances for a clear diagnosis are not the best.
Diagnosing Meniere’s Disease
We recently saw a 68-year-old gentleman, describing a several month history of recurrent episodes of vertigo, lasting 30 to 60 minutes. The most recent episode was just a few days before his appointment. Prior VNG testing performed at the referring ENT office had demonstrated a 65% reduced vestibular response (RVR) on the right. He denied any associated auditory symptoms with the episodes, but he had a mod/severe flat SNHL on the right. He reported that the hearing had decreased progressively over a year or two, with onset of persistent tinnitus, TEN YEARS EARLIER.
And for those of you thinking, “Hmmmm, recurrent vertigo with no associated auditory symptoms. Sounds like migraine.” He had no history of migraine, and no associated migraine symptoms.
So, what we had here was someone who probably had endolymphatic hydrops who would not meet the established criteria for MD due to the pre-existing idiopathic unilateral SNHL. Would he be able to detect minor changes in hearing or tinnitus with the episodes? What could we do to clarify the picture?
We have noticed over the past few years that most MD patients, despite having a significant caloric weakness, typically have normal vHIT tests. Two recent papers back up our observation.
In 2014, Bidow et al demonstrated that only one in three MD patients with significant caloric asymmetry had an abnormal vHIT. Their study was primarily focused on the ability of vHIT to clarify MD from vestibular migraine patients.
A more recent study by Hannigan et al (2019) found normal vHIT with abnormal caloric test results in roughly 36% of patients diagnosed with MD. This pattern was noted in less than 2% of patients in the non-MD group.
vHIT a Complimentary Test, Not a Substitute for Calorics
Back to our patient. We decided to not repeat caloric testing. Rotational chair and vHIT were normal and symmetrical. Skull vibration elicited a time locked left beating nystagmus, consistent with the prior diagnosis of right hypofunction.
Our conclusion was that this test pattern most likely represented atypical MD on the right. If the right hypofunction had been associated with any disease other than MD, such as labyrinthitis, we would have expected an abnormal vHIT. In this situation, vHIT served as a complimentary test to caloric irrigation, not a substitute.
*featured image courtesy Micromedical Technologies