Vagus nerve stimulation shown to suppress CSDs – a trigger for migraine

According to a new study, vagus nerve stimulation (VNS) was found to suppress cortical spreading depression (CSD) – a trigger for migraine.

CSDs are believed to be responsible for the aura, or visual disturbance, that frequently precedes some migraines, and have been a significant target for pharmaceutical development.

The controlled study, led by scientists at Massachusetts General Hospital, Harvard Medical School, had five groups of animals; non-invasive VNS; surgically implanted VNS; sham group – electrodes were implanted but never stimulated; femoral nerve stimulation group; and naïve animals. CSD was elicited by either a continuous topical KCI application or by electrical stimulation.

In this study, VNS was shown to raise the level of resistance to electrically and chemically triggered CSDs by threefold.  The researchers also found that VNS suppressed CSD by this amount within 30 minutes of the first administration of the therapy, which is significantly superior to commonly used migraine prophylactic drugs that typically take several weeks to achieve comparable results.

This study further showed, for the first time, that non-invasive vagus nerve (nVNS) stimulation was as effective as surgically implanted vagus nerve stimulation (iVNS) in significantly reducing CSDs by, up to 40%. The non-invasive VNS treatment, which involves the delivery of two brief 2-minute doses, was able to suppress CSDs for the full three-hour duration of the study, with no indication that the efficacy had yet diminished.

Stimulating vagus on one side of the neck was sufficient

Interestingly, stimulating vagus on only one side of the neck was sufficient to suppress CSDs triggered on both sides of the brain suggesting that nVNS may be useful in treating unilateral or bilateral headaches, independent of which side of the neck is stimulated.

Dr Cenk Ayata, commented, “We have established that VNS reduces cerebral excitability as shown by CSD suppression, and that VNS has a strikingly rapid onset of action compared to traditional migraine prophylactic agents, such as topiramate and valproate. We also established that both the non-invasive hand held gammaCore device and surgically implanted device should be equally effective in reducing cortical spreading depression.”

Reducing CSD is a validated platform for screening pharmacological therapies for migraine with aura. The researchers believe that VNS works through the modification of neurotransmitter levels and potentially an affect on local and circulating cytokines.