Vol. 4, No. 17, December 2005


Current Psychiatry September 2005                         


Vagus Nerve Stimulation:  Surgical Option for Treatment-Resistant Depression
by Jeffrey Rado, MD, MPH and Philip G. Janicek, MD, Dept. of Psychiatry,
Rush U. Medical Center, Chicago, Ill.

Clinical Applicability

* VNS is indicated for patients with chronic or recurrent
treatment-resistant depression that has not responded to at least 4
adequate
antidepressant treatment trials
* Implementation theoretically promotes 100% adherence and reduces
drug-drug interactions
* Interaction between VNS and nonpsychotropic medications are
possible, but unlikely
* Paradoxically, patients with low to moderate resistance to
antidepressant treatment (<3 treatment failures) are most likely to
benefit; patients who have never received ECT are 4 times more likely to
respond; and patients who have not responded to >7 trials of medications did not
respond

How VNS Works

* Vagus (10th cranial nerve) is a main efferent outflow tract for parasympathetic innervation of the abdomen and chest, regulating heart rate, acid secretion, and bowel motility
* 80% of the left vagus nerve conducts information about pain, hunger and satiety and are thought to contribute to VNS antidepressant effect via information to the solitary nucleus of the medulla; from there, fibers project to the median raphe nucleus and locus coeruleus, key areas of serotonergic and noradrenergic innervation relevant to depression
* VNS increases blood flow to the thalamus, hypothalamus and insula--also relevant to depression

* FDA approved VNS for epilepsy in 1997 - it was noted to improve epilepsy patients' moods; it could also help with anxiety disorders, obesity, pain syndromes and Alzheimer's Disease

Technique

* Subcutaneous implantation of pacemaker-like pulse generator into the upper left chest; wires extend from generator into left vagus nerve in neck; 1-2 hour operation usually by neurosurgeon

* Device sends electric pulse to vagus nerve every few seconds; stimulation paramet. programmed

 

Cost

* $25,000 for implantation including device, surgeons fee and facility charge; usually follows psychiatric referral; battery life is 6-8 years with follow-up surgery needed to replace battery
* Follow-up visits for epilepsy are $150 - $250 per visit; generally insurers cover VNS for epilepsy

 

Efficacy in Depression

* 3 months after implantation, 18/59 patients in open trial: (30.5%) showed >50% response
* Median time to first response 45.5 days (stimulator turned on after 2 wks, max dose 4 wks)
* Patients with mild to moderate depression had better response rate than severely depressed

* After 1 year, 46% better, 29% in remission; after 2 years, 44% better, 22% in remission
* 235 subjects in double-blind, sham controlled trial after 1 year: 29% response, 17% remission

 

Side Effects

* Voice alteration or hoarseness in 55%; headache 22%, cough 17%, SOB 15%; neck pain 17%, dysphagia 20% - all ameliorated by reducing the dose; infection and nerve damage 1%

Availability:  Device manufacturer plans to offer free VNS training to psychiatrists who practice at selected centers that accept treatment-resistant depression case referrals from primary care physicians, community psychiatrists and other providers.