Timothy C. Hain, MD Page last modified: November 10, 2008
It is generally easy to find testimonials for various medical procedures, but unfortunately there are also some quite poor outcomes. In Chicago Dizziness and Hearing, we are often sent people in whom other doctor's have tried and failed to cure their dizziness. One should not draw the conclusion that the procedures being discussed are ineffective, but we hope that this will assist in keeping patients informed concerning the bad as well as good outcomes of a proposed intervention.
A woman in her 20's with a long history of migraine headache developed gradual onset of dizziness. This was in the context of long-standing headaches, thought to be migrainous due to exacerbation by bright sunlight, as well as being unusually prone to develop motion sickness.
She was sent for evaluation to a neurotologic surgeon, who did an ENG test on her, which documented a mild vestibular weakness (roughly 40-50%) on the right side. Hearing was normal as well as her MRI scan. The surgeon felt that she had a partially healed vestibular neuritis, and performed a vestibular nerve section on the right side. The surgeon subsequently also performed a "microvascular decompression" surgery on the other side.
Following the vestibular nerve section, as well as the second surgery after about 2 months of relief, she continued to experience dizziness and headaches, and ultimately became disabled. She was seen at several prominent tertiary care referral centers, with the overall conclusion that she had vestibular migraine.
Multiple studies documented complete loss of vestibular function on the operated side.
|Caloric testing documented no response on the right side. There was also no response to ice water. This is the expected result of a VNS.|
|VEMPs were absent on the right side. This is the expected outcome of a VNS.|
|Rotational chair testing documented reduced gain and a "tilting" of the phase as should be the case for unilateral loss. Notice that the asymmetry measure was normal here, in spite of a 100% asymmetry known from surgery. This shows that the asymmetry measurement of rotational testing cannot be relied upon.|
|Vibration over the SCM elicited a strong left-beating nystagmus. This is the expected outcome of a VNS. Cervical testing (turning the head to one side) elicited both left-beating and upbeating nystagmus.|
In this woman, it is obvious that her dizziness was not due to a partially healed vestibular neuritis, or due to microvascular compression, as surgery for these two conditions was ineffective. It seems most likely that her dizziness and headaches were due to intractable vestibular migraine. Hindsight is 20-20.
In the population, vestibular migraine is several ORDERS OF MAGNITUDE more common a source of dizziness than irritible vestibular nerves due to a previous vestibular neuritis. While the latter condition clearly does exist, and VNS does seem reasonable as a last resort (after medication has failed and a reasonable wait of several years), there are only a very few and rare cases in which these criteria are met.
We strongly suggest that persons with dizziness and migraine get a second opinion from a non-surgical dizziness specialist before proceeding with a VNS.