A recent meta-analysis looked at noninvasive vagus nerve stimulation (nVNS), a nonpharmacologic method of acute pain relief for headaches.
The study investigated the effectiveness and safety of peripheral nerve stimulation of the cervical branch of the vagal nerve in primary headache disorders.
The authors note that primary headache disorders (migraines, cluster headaches, and tension‐type headaches) are a leading cause of disability. Globally, the prevalence of tension‐type headaches is about 20.1%, migraine is approximately 14.7%, and cluster headaches about 0.1%-0.4%.
The major parasympathetic branch of the autonomic nervous system, the vagus nerve transmits or mediates sensory information to the brain.
“The mechanism of action of nVNS in the treatment of headache is largely elusive and likely multifactorial,” said the authors, writing in Neuromodulation. To their knowledge, this is the first meta‐analysis to probe the effectiveness of nVNS in these types of headaches, they said.
The authors searched the Medline, Embase, and CENTRAL databases and used a random‐effects model to report all outcomes where nVNS was used to treat headaches in randomized controlled trials (RCTs).
Studies were included if the population included patients diagnosed with primary headache disorders, according to the International Classification of Headache Disorders (ICHD)‐II or ICHD‐III beta version); if the intervention compared cervical nVNS with sham‐device treatment or standard care; and if outcomes were measured by a reduction in headache days or attacks, pain‐free status, pain‐relief status, abortive medication use, ≥50% responder rates, adverse events, or satisfaction.
Researchers determined study quality with the Revised Cochrane tool for assessing the risk of bias.
The literature search yielded 746 articles, and of those the authors reviewed 51. Ultimately, 7 articles in 6 clinical trials were included in the review. The 6 trials included 983 randomized patients (486 to nVNS and 497 to a control).
Three trials enrolled migraineurs (n = 634) and 3 other trials recruited patients with cluster headache (n = 349). Females made up the majority of the migraine population, and males made up most of the cluster headache participants. The percentage of preventive medication use ranged from 28.5% to 90%.
In 5 trials, the control was sham treatment with an identical device and standard care while 1 trial used only standard care. Therapy lasted from 2 to 12 weeks.
Compared with sham‐device treatment, results showed that overall, nVNS was effective at providing acute pain relief. Specifically, the outcomes were:
There were no significant differences in decreased headache days, adverse events), or satisfaction between nVNS and sham‐device treatment. Additionally, the ≥50% responder rate could not be determined.
However, some unanswered questions remain due to limited data, and larger RCTs are needed, they said.
Lai YH, Huang Y, Huang LT, Chen RM, Chen C. Cervical noninvasive vagus nerve stimulation for migraine and cluster headache: A systematic review and meta-analysis. Neuromodulation. Published online March 12, 2020. doi: 10.1111/ner.13122