Originally created 05/08/02

Easing pain with brain implants



Brain surgeons are no longer content with mere cutting or burning. Now, they are increasingly turning to implanted electrical devices - battery- powered pacemakers for the brain - to tweak faulty neural circuits.

Electrical stimulation, or "neuromodulation" as the technique is called, is frequently used for Parkinson's and other movement disorders, and spinal cord stimulation is an accepted option for intractable back and limb pain.

Now, the approach is moving into new territory following the discovery that a little electrical stimulation, judiciously applied, can have some surprising effects.

An electrode planted just above the movement-controlling motor cortex, for instance, appears to generate changes deeper in the brain, perhaps increasing blood flow and quieting overactive nerves in an important message-relay area known as the thalamus.

The result, for at least a few patients, is an astonishing reduction in symptoms of chronic nerve pain. The technique has yet to be proven long term but is gathering some adherents, particularly in cases of hard-to-treat pain syndromes in the face and nerves hooking directly into the brain.

"This is not experimental," said Dr. Jeffrey Brown, neurosurgeon at Wayne State University School of Medicine in Detroit, among the pioneers of the modern form of "motor cortex stimulation," or MCS, for pain. "The reason it's been discovered lately is that we have computer navigation of the brain now, which allows us to accurately position the electrode and makes this surgery more practical."

It's considered reversible, and less potentially damaging to delicate brain structures than other surgical options.

Despite a long and sometimes scandalous history of botched "psychosurgeries, " some propose electrical repairs be tried for some psychiatric conditions, in particular the most difficult cases of obsessive-compulsive disorders and major depression that don't respond to medications or counseling.

Instead of making a permanent cut or lesion, the idea is to use precisely configured pulses of electric current from an implanted programmable device. Although it's often unclear how this might affect brain circuits, the basic idea of using an electric jolt for a neurological condition is hardly new.

Medical historians say it was mentioned in Roman times for rheumatic pain. The physician-philosopher Galen is said to have recommended the shock of the Mediterranean torpedo fish, a common electric ray, for migraines, while Hippocrates may have used it for treating asthma.

More traditional neurosurgery for pain typically involves cutting or burning a problem nerve pathway. That can often produce at least some temporary relief, and may remain the best alternative for treating late-stage cancer pain.

MCS has been around since the 1980s, originating in Japan, but has only lately become an accepted alternative in the United States. Brain imaging is used to identify the target area and plan the approach. A paddle-shaped electrode is then placed above that spot, just above the dura mater, the brain's protective covering beneath the skull.

One big advantage, Brown noted, is the ability to remove the stimulator if it proves ineffective. "Certainly you want to try to do nothing damaging to the brain if you can," he said. "You want to try to help the brain heal itself. "

Some patients describe the results as little short of astounding.

"It was the most remarkable thing," said Stuart Burnstein, 52, a Detroit salesman who suffered through years of excruciating nonstop pain after several failed eye operations. "For the first time in 15 years, I was out of pain."

Burnstein said he was willing to take the gamble - even if the payoff doesn't last. "Pain was consuming my life. Even if I get only two years of relief I would be a happy camper," Burnstein said.

Brain specialists said many more patients need to be followed to gauge long- term success. Meanwhile, the first small clinical trials are just under way in epilepsy and obsessive-compulsive disorders.

Pacemaker for pain

Electrical stimulation of the brain has become an important method for treating symptoms of Parkinson's disease and other movement disorders. Now, neurosurgeons are trying a modified form of the same system to alleviate chronic pain arising from the face or neck. Here's how it works:

1. An electrode is implanted beneath the skull against the dura, a protective membrane that covers the brain. The electrode delivers pulses of electrical stimulation through the membrane to an area known as the motor cortex, a part of the brain involved in movement and sensation.

2. A battery-powered neurostimulator is implanted near the collarbone. A wire beneath the skin connects the device to the wire lead in the head. The connecting wire goes up the back of the neck and under the scalp.

3. Physician uses an external radio transmitter to adjust the electrical pulses.

4. Signals from the motor cortex appear to trigger effects deeper in the brain, easing pain, by increasing blood flow and quieting overactive nerves in areas such as the thalamus and cingulate gyrus. But the long-term benefits are unproven.