Stimulation of Vagus Nerve may Prevent Migraine Attacks

A recent study indicates that stimulation of the vagus nerve could prevent migraine attacks. The study, which was conducted in animals, was published in the journal Pain. The study focused on an aspect noted in patients with migraine called cortical spreading depression. Cortical spreading depression is a brain phenomenon that consists of electrical changes in the brain during the aura phase of a classic migraine attack. During the aura phase, the patient experiences flashing lights, unpleasant smells or even hallucinations. It serves as a warning sign that the person is going to have a migraine attack.

Several drugs are available for the treatment of migraine. The most commonly used are painkillers and the triptans like sumatriptan, rizatriptan and naratriptan. Drugs are also available to prevent migraine attacks and include anti-seizure drugs, antidepressants and certain blood pressure medications. Some patients, however, suffer from severe forms of the condition and do not respond to treatment.

Researchers believe that stimulation of the vagus nerve can prevent migraine attacks. The vagus nerve is an important nerve that supplies to the heart, lungs and abdominal organs. Stimulation of the vagus nerve via a small stimulator surgically placed under the skin has been tried in patients with neurological conditions like epilepsy and depression who do not respond to conventional treatments.

In the experiment carried out in rats, cortical spreading depression was produced through the local application of potassium chloride solution or via electrical stimulation. Vagus nerve stimulation was administered either on the skin over the vagus nerve or directly on the vagus nerve. The researchers found that:

i) Cortical spreading depression was significantly reduced within 30 minutes of the vagus nerve stimulation. The preventive action of vagal nerve stimulation appears to be quicker than what is achieved with the medications used to prevent migraine like topiramate and valproate, which require a longer time to act.

ii) Stimulation of the vagal nerve through the skin had a similar effect as compared to when the nerve was directly stimulated. This implies that a surgery to insert the stimulator may not always be needed.

iii) Stimulation of the vagus only on one side was needed to bring about its effect, irrespective of which side of the head was affected by the migraine.

iv) Vagal nerve stimulation did not cause major changes in the heart rate and blood pressure of the rats. Thus, the procedure appears to be relatively safe in treating migraine.

If similar benefits are also noted in humans, vagal nerve stimulation without the need for surgical implantation of the device can emerge as an important preventive measure in migraine patients.

References

Chen SP, Ay I, Lopes de Morais A, Qin T, Zheng Y, Sadhegian H, Oka F, Simon B, Eikermann-Haerter K, Ayata C. Vagus Nerve Stimulation Inhibits Cortical Spreading Depression. Pain. 2015 Nov 25. http://www.ncbi.nlm.nih.gov/pubmed/26645547

Source - Medindia