Psychiatrists at Rush University Medical Center are the first in Chicago to use a vagus nerve stimulator (VNS), an implantable, pacemaker-like device, as a therapy to treat long-term, treatment-resistant depression (TRD) in adults. Dr. John Zajecka led the VNS therapy clinical trial at Rush.
The procedure to place the device, which is usually performed under general anaesthesia on an outpatient basis, takes about an hour. Two small incisions are required: one on the upper chest area for the pulse generator and one on the left neck for the thin, flexible wires that connect the pulse generator to the vagus nerve. The incisions heal in one to two weeks, and the scars fade over time.
“The pulse generator, which is like a pacemaker, is implanted in the chest area and sends mild pulses to the brain via the vagus nerve in the neck. A thin, thread-like wire attached to the generator, runs under the skin to the left vagus nerve. The vagus nerve, one of the 12 cranial nerves, serves as the body’s ‘information highway’ connecting the brain to many major organs,” said Zajecka.
The device delivers very mild, intermittent, brief pulses to the left vagus nerve. The pulses are then transmitted via the nerve to the central nervous system, to specific areas in the central nervous system that control mood, motivation, sleep, appetite, and other symptoms that are relevant to depression. Several studies have shown that VNS Therapy may modulate neurotransmitters such as serotonin and norepinephrine thought to be involved in mood regulation, according to Zajecka.
VNS Therapy is approved by the Food and Drug Administration as a long-term adjunctive (add-on) treatment for patients 18 years of age and older who are experiencing a major depressive episode and have not had an adequate response to four or more antidepressant treatments. VNS Therapy was approved for the treatment for some patients with epilepsy in 1997, and is now the first treatment specifically studied and approved for treatment-resistant depression.
Major depressive disorder is one of the most prevalent and serious illnesses in the US, affecting nearly 19 million Americans every year. Of those, 20 percent experience depression that does not respond to multiple antidepressant treatments. For these people, attempts at treatment may have included psychotherapy, antidepressant medications and sometimes electro-convulsive therapy, but they are effective for a short while and stop working over time.
“Patients with TRD need additional options,” said Zajecka. “The availability of VNS Therapy is an important treatment option for millions of people who, until now, have not had access to a proven long-term option to control depressive symptoms. It is especially important to know that clinical study results have shown that patients achieve increasing benefits from VNS Therapy over time and experience sustained results. Additionally, VNS Therapy is very tolerable, and side effects typically diminish over time.”
Three percent of patients in the clinical trial experienced side effects of incision pain; voice alteration; incision site redness/itching, pain around the device and swelling and tenderness.
Zajecka says that in clinical studies of VNS Therapy, more than half of the patients who had experienced an average of 25 years of major depressive disorder and multiple treatment trials realised some clinical benefit, one third of the patients had at least a 50 percent improvement in their depression. One out of six patients were depression-free after one to two years of treatment with VNS Therapy. Patients also reported significant improvements in quality-of-life areas, such as vitality, mental health, emotional well-being and social functioning.