Wednesday February 16 6:18 PM ET
BOSTON (Reuters) - When the tremors of people with Parkinson's disease or multiple sclerosis can't be controlled with drugs, doctors sometimes destroy a small portion of the brain in an effort to relieve the quivering.
But a study in Thursday's New England Journal of Medicine shows that delivering electrical impulses to that same area of the brain may be just as effective, with fewer serious side effects.
Researchers in Amsterdam tested 67 volunteers and found that electric stimulation dampens the tremors the same way that destroying a small area of the brain does. But the newer technique, thalamic stimulation, is less destructive than the traditional surgery, known as a thalamotomy.
"For the time being, thalamic stimulation is preferable to thalamotomy as a means of improving function with few adverse effects,'' researchers said.
However, researchers said, neither treatment is effective in all patients.
The focus of the research is the thalamus -- two joined walnut-sized bundles of nerves located near the core of the brain. They serve as a relay station for electrical impulses.
In a thalamotomy, doctors severely damage one bundle of nerves by inserting a probe and heating the tip to 175 degrees F. (80 degrees Celsius) for one minute. The procedure helps relieve incapacitating tremors in 73 to 93 percent of patients, but causes permanent complications in up to 41 percent of cases.
With the electrode procedure, surgeons insert a wire with four electrodes into the thalamus. The electrodes are connected to an implanted device that generates electrical pulses.
In the Amsterdam study, Dr. Richard Schuurman and his colleagues at the Academic Medical Center compared the results of 34 volunteers who underwent the traditional surgery with 34 treated with four implanted electrodes.
With both treatments, the results were dramatic. In the people with the thalamotomy, 26 said they had a complete suppression of their tremors after six months. The same was true for 28 volunteers treated with the electrodes.
One of the authors, Johannes D. Speelman, told Reuters that the effect of the electrodes did not wear off over time.
The treatments seemed to work best in patients with Parkinson's disease, and were less effective in volunteers with multiple sclerosis.
But there were side effects. One electrode recipient died from complications of the surgery. Some people who underwent the thalamotomy surgery couldn't reason as well afterward, one developed language problems, another felt decreased initiative.
Volunteers treated with the electrodes complained of fewer side effects, yet some reported slurred speech, tingling sensations, balance problems, or limb weakness. Those problems could be eliminated by turning off the electrodes, but many patients chose not to because they felt that the benefits were worth the side effects.
In an editorial in the Journal, Dr. Gunther Deuschl of Christian Albrechts University in Kiel, Germany, said the research offers "a strong argument for the use of deep-brain stimulation as the treatment of choice'' for patients like those involved in the Schuurman study.
"But patients so treated must be followed closely at specialized centers,
and the costs of therapy are much higher than those of thalamotomy'' because
of the need to adjust and maintain the stimulation equipment, Deuschl said.