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Vagus nerve stimulation . . .
At least 1 of every 100 Americans has epilepsy, a disturbance in the brain’s electrical activity causing recurrent seizures. These may be as mild as twitching fingers or as severe as violent muscle contractions causing unconsciousness. But we’ve come a long way since the disorder was considered demonic possession, and doctors have a slew of medicines that often keep the disorder in check.
Unfortunately, not every epileptic reacts well to medicine. In 25% to 40% of patients medications don’t effectively treat the disorder, either because they don’t reduce seizures or cause intolerable side effects. Many are thought to pose a risk of birth defects.
That’s where implantable vagus nerve stimulators (VNS) come in. Not to be confused with the ”Vegas nerve, ” which promotes a desire to play slot machines and roulette, the vagus nerve starts in the brainstem and extends down past the head to the abdomen.
You may think the bionic VNS devices are inserted into the brain, the thought of which gives many of us the heebie-jeebies. But actually it’s implanted just under the skin in the patient’s chest during an outpatient procedure. ”They’re not noticeable in adults or even small children, ” says Dr. Jim Wheless, Director of Le Bonheur Comprehensive Epilepsy Program at the University of Tennessee.
Small wires from the device, currently made only Cyberonics of Houston, Texas, are tunneled under the skin to the left vagus nerve in the neck. Through them are sent timed and measured electrical signals that, in pacemaker fashion, activate various areas of the brain.
But unlike with a pacemaker, recipients of VNS devices can temporarily adjust the strength of that pulse merely by running a magnet over the device. ”If you’re on medicine and feel a seizure coming on, there’s nothing you can do to abort it, ” Wheless told me. ”But patients can use that magnet to – in many cases – abort, shorten, or improve recovery from the seizure. ”
Ah, but too late if it’s a massive convulsion (called a ”grand mal seizure ”), right? Wrong. ”A family member can also use the magnet, ” Wheless points out.
. . . and the vagus nerve stimulator.
Wheless, a neurologist of 18 years who has used the VNS devices since they became available in the U.S. in 1997, nevertheless always begins with pharmaceutical therapy. ”Usually we consider that if patient hasn’t responded adequately to two to three drugs, VNS therapy may be appropriate, ” he says.
That’s sensible, because VNS epilepsy therapy costs $20,000 to $25,000, device and surgery included. Medicare and most insurance companies do cover it, though. And Wheless says while data from the US are varied because we don’t have a uniform health care system, ”In Europe, the device has been cost-effective ” because it reduces expense from hospitalizations and injuries in general.
Worldwide almost 40,000 VNS devices are in use. One major study showed that after three years, almost three-fourths of VNS implant recipients continued to receive the therapy. Further, for those whom it does help, the benefits tend to improve over time. ”We often see gradual improvement not just in the first weeks or months but sometimes out to even 18 months, ” says Wheless.
VNS devices can also be used in conjunction with epilepsy drugs, reducing the needed amount and thereby reducing the possibility of side effects.
For epileptics with the mildest of convulsion, VNS devices aren’t recommended but neither are they only for those who suffer seizures grand mal. Actually, ”Most of the devices are for complex partial seizures such as stopping activity, unresponsiveness, and confusion, ” says Wheless. ”These are no less devastating than grand mal seizures. ”
VNS therapy isn’t without side effects, but they tend to be mild including local irritation, hoarseness, and coughing, and these generally disappear with time. ”
Says Wheless, ”If you adjust the device properly you can get close to virtually no side effects. ” Further, ”You can make settings in office. I can determine results with patients standing in front of me. You can’t do that with medicine. ”
The FDA recently approved VNS therapy for severe clinical depression, and progress with other bionic implants shows we’re truly in an exciting new age therapies for mental disorders for which the ”treatment ” not so long ago was being chained to a sanitarium wall.