Vagus Nerve Stimulator
The vagus nerve stimulator (VNS), manufactured by Cyberonics, is
a new and promising alternative for medically refractory seizures,
treatment-resistant depression and in one isolated case, the "hiccups".
Medically refractory seizures are those in which patients have tried two or more
medications and are still not satisfied with seizure control, side effects, and
the quality of their life. Treatment-resistant depression is where the
patient has exhausted all alternatives, including psychotherapy, multiple trials
of medications, and electroconvulsive therapy (ECT).
Similar to a stopwatch-sized pacemaker, a VNS is a small device
implanted under the skin near the collarbone, or close to the armpit. Two
tiny wires from the device wrap around the vagus nerve on the left side of
the neck. While this may sound serious, the procedure involves two small
incisions, takes about an hour, and is often done on an outpatient basis.
Once implanted in the body, the battery-powered device can be programmed from
outside the body by a doctor. A handheld magnet can also be used to turn
the device on such as in the case of a seizure patient feeling a seizure about
to start. The doctor programs the device to produce weak electrical
signals that travel along the vagus nerve to your brain at regular intervals.
These signals help prevent the electrical bursts in the brain that cause
seizures. For acute, chronic, treatment-resistant depression VNS is
something of a mystery to scientists. It is believed that electrical
stimulation alters the chemical neurotransmitters that carry messages across the
gaps, called synapses, between nerve cells.
The VNS is considered safe. It has been approved by the
U.S. Food and Drug Administration (FDA), and this type of treatment is an area
of ongoing research.
Mild side effects occur in some people when the device
stimulates the nerve. The most common side effects include coughing,
throat pain, hoarseness or slight voice change, a prickling feeling on the skin,
and shortness of breath. In children, VNS has caused hyperactivity.
These side effects become less noticeable over time. However, clinical
studies show that VNS has resulted in an improvement in alertness, memory, plus
more energy and a better mood.
In one isolated case, a man in New Orleans, after
suffering seven months of constant, bark-like hiccups has had the VNS device
implanted in his chest and now has returned to his normal life as a 50 year old.
His speech is now a hoarse whisper which is one of the side effects of the
treatment. But, for the first time since November 2003, he can eat, sleep
and no longer has to make himself gag to make the hiccups stop. He can
talk without a bark-like hiccup every three to four seconds.
In 2006, Cyberonics will invest aggressively in new studies to
test the effectiveness of VNS on Alzheimer's disease, anxiety and headaches.