Vagus nerve stimulation
This procedure involves the stimulation of the vagus nerve. Vagus nerve is one of the 12 pairs of nerves originating in the brain. It has motor functions in the voice box, stomach, diaphragm and heart and sensory functions in the ears and tongue. Stimulation of the vagus nerve is said to affect some of its connections in the brain that affect depression.
This procedure is recommended for patients 18 years and above and who have not responded to medications for depression for more than four years. Research proves that patients with chronic depression continue to respond to vagus nerve stimulation for up to two years. Sufferers either find a relief with total elimination or partial reduction of symptoms.
The surgical procedure explained
This surgery is performed under general anesthesia. Two incisions are required. One on the left side of the upper chest and the other at the neck where the lead is wrapped around the vegas nerve. A small stopwatch sized generator is implanted in the upper left portion of the chest. A thin wire runs just below the skin to the vagus nerve in the left part of the neck. The surgeon attaches three leads to this wire. The leads are wrapped around the left branch of the vagus nerve in the neck. The electrodes are connected to the generator. The generator sends electrical impulses according to the set programmed duration every five minutes. The duration of the stimulation lasts for not more than thirty seconds. The whole surgical procedure takes an hour.
The left vagus nerve is stimulated rather than the right because the right nerve plays an important role in the cardiac functions and stimulation might affect the heart.
Working of VNS
The exact working of VNS is unknown. It affects the blood flow to the different parts of the brain which affect neurotransmitters including serotonin and norepinephrine which are related to depression.
Benefits of VNS
- Depression when treated with antidepressants was effective for 1 out 8 people. VNS is effective for 1 out of 3 people.
- Effectiveness of VNS improves over time and longs for a longer duration.
- VNS therapy reduced the need for antidepressants for some people.
- Many people who did not show a marked change immediately after the VNS procedure showed much improvement after a year.
- Patients also report emotional well being and a greater mental health.
Side effects
Damage to the vagus nerve is a possibility.
Coughing, difficulty swallowing and changes in the voice quality are associated side effects. Typically these happen only when the stimulation is on.
Efficacy of VNS is proved for epileptic seizures. Its effectiveness as a cure for depression is still under study. Latest research proved that 40 out of 100 patients showed more than 50% of improvement. As the vagus nerve is associated with different functions of the brain further research is being carried out to see the usefulness of this treatment in treating Alzheimer’s, migraines and varied other brain disorders.