Noninvasive vagus nerve stimulation (VNS) provides rapid relief of vertigo and
headache in patients with acute vestibular migraine (VM), results of a small study suggest.
In the wake of these promising early findings, study investigator
Shin C. Beh, MD, assistant professor of neurology, University of Texas,
Southwestern Medical Center, Dallas, encourages clinicians to try novel
neuromodulatory approaches like vagus nerve stimulation for their VM
patients.
“It’s safe, with not much risk to the patient. I’d say go for it; try it out,” he told
Medscape Medical News.
The study was
published online September 25 in
Neurology.
Common Cause of Vertigo
VM is the most common neurologic cause of vertigo. All patients with
VM have vertigo as a manifestation of migraine, but they may or may not
have headache and, if they do, it is often less severe than pain
associated with typical migraine.
The cause of VM, which affects 1% to 2.5% of the population, is
primarily linked to genetics. Compared with other migraine types, it is
much more common among women than men.
There are no approved treatments for acute VM. Even though headache
may not accompany VM attacks, clinicians tend to extrapolate therapeutic
approaches from
migraine headache guidelines.
Analgesics may not be effective for acute VM. Antiemetics and
medications that quiet down the entire vestibular system are sometimes
used, said Beh, but these may cause sedation and impair engagement in
daily activities. In addition, although triptans may be useful, the
evidence for their use in VM is inconclusive.
VNS has been shown to be safe and effective for acute migraine. The US Food and Drug Administration has cleared the hand-held
gammaCore (electroCore) for migraine, as well as
cluster headache, in adults.
The retrospective study included 18 patients (16 women and two men),
with a mean age of 45.7 years, diagnosed with VM. The diagnostic
criteria include at least five episodes of moderate or severe vestibular
symptoms. Some patients in the study described these episodes as a
spinning or rocking sensation.
The criteria also require that 50% or more of these episodes be
associated with at least one of three migrainous features. These include
migraine headache, photophobia and phonophobia, and visual aura.
Study participants were all patients Beh was seeing in his clinic. Of
the 18 participants, 14 were in the midst of an acute VM attack.
“They happened to show up to clinic with an attack and had no
medication on hand. The best solution I could come up with was to offer
the stimulation,” he said.
Quick, Safe, Noninvasive
Prior to VNS treatment, patients graded the severity of their
vertigo/dizziness and headache, if present, using a visual analog scale
(VAS) with 0 representing no symptoms and 10 the worst imaginable.
Although some participants were on pharmacologic migraine prevention,
none had taken any migraine abortives, antiemetics, or vestibular
suppressants within 24 hours of the intervention.
Under supervision, patients used the device to deliver bilateral
120-second electrical stimulations to the right front and then to the
left front of the neck.
“It’s quick — 2 minutes on each side,” said Beh. “It doesn’t cause any sedation.”
Patients graded their vertigo/dizziness/headache using the same VAS 15 minutes after VNS treatment.
“The most significant finding was that the vertigo got better,” said Beh.
In the 14 participants who were having a VM attack, 13 reported the
vertigo improved and one reported no benefit. Of those who experienced
improvement, two had complete resolution and several described at least a
50% improvement in vertigo severity.
The mean vertigo intensity was 5.2 before VNS and 3.1 after treatment. The mean reduction in vertigo intensity was 46.9%.
Only five patients experienced a headache with their VM attack. One
experienced complete resolution after stimulation and four reported at
least a 50% improvement in headache intensity.
Potential Mechanisms
Mean headache severity was 6 prior to VNS and 2.4 after treatment. Mean reduction in headache intensity was 63.3%.
Four of the 18 participants who just had interictal dizziness reported no benefit from the treatment.
Beh believes that the stimulation may work through nuclei located in the brain stem.
“One of the nuclei, the nucleus tractus solitarius, is of particular
interest because the trigeminal system, vestibular system, and vagal
system all connect through that nucleus,” he said.
“That nucleus has been found to be responsible for nausea in migraine
and for motion sickness, so that may be the most likely candidate,” Beh
explained.
But there’s evidence that the effect may not be limited to the brain
stem. Beh cited research suggesting that VNS causes changes in multiple
areas of the brain, including the thalamus, parietal lobes, and temporal
lobes, which are areas involved in the processing of vestibular
information.
“I think what’s happening is that by stimulating the vagus nerve,
you’re altering the activity within the vestibular system. By doing
that, you shut down the spreading processes of a migraine, so whatever
electrical dysfunction was causing the migraine, stimulating the vagus
nerve somehow manages to shut that down,” he said.
Aside from patients reporting slight discomfort on the neck during
the stimulation, there were no side effects of the intervention, said
Beh.
“This is very safe and very well tolerated. None of my patients
complained about anything negative. The muscles of the face might pull a
little bit, but that’s about it.”
Beh hopes to carry out larger studies to test VNS for rescue
treatment of vestibular migraine, and possibly for prevention. Such
studies would need to have a sham-control design, he said.
Commenting on the findings for
Medscape Medical News, Ji-Soo
Kim, MD, PhD, professor, department of neurology, Seoul National
University College of Medicine, who, along with colleagues, recently
identified a new and possibly treatable type of vertigo known as
recurrent spontaneous vertigo. This disorder is not accompanied by
neurologic symptoms and does not meet diagnostic criteria for vestibular
migraine, Ménière disease, or
vestibular neuritis.
“Even though I don’t have any experience with VNS, this study may
provide a promising opportunity to develop a noninvasive therapy for
vestibular migraine,” said Kim.
“This advantage seems to balance the limitation of a retrospective design on a small number of patients,” he added.
Beh and Kim have reported no relevant financial disclosures.
Neurology. Published online September 25, 2019.
Abstract
https://www.medscape.com/viewarticle/919203#vp_1