Gamma Knife Relieves Uncontrollable Tremors

Radiation Technique Just as Effective, With Fewer Complications, Than Other Treatments

Medically Reviewed by Louise Chang, MD on November 03, 2009
From the WebMD Archives

Nov. 3, 2009 (Chicago) -- A high-tech procedure that delivers radiation deep within the brain relieved uncontrollable shaking and tremors in more than 80% of patients in whom it was tested.

The procedure uses a gamma knife to target brain cells that work overtime in people with tremors, says Rufus Mark, MD, of the Joe Arrington Cancer Center and Texas Tech University, both in Lubbock, Texas.

In some people, the tremors are a hallmark symptom of their Parkinson’s disease. Others have a condition called essential tremor that is associated "with incapacitating shaking. People can't hold a coffee cup and their handwriting in illegible," he tells WebMD.

Not really a knife, the gamma knife is a device that emits powerful, highly focused gamma radiation beams. This helps the doctors target a specific area of the brain while sparing healthy surrounding tissue. Also called stereotactic radiosurgery, it's used to treat people with brain tumors, Parkinson's disease, and other neurological disorders.

Gamma Knife Relieves Uncontrollable Tremors in 84% of Patients

Mark and colleagues studied 183 people who underwent radiosurgery for hard-to-treat tremors between 1991 and 2007.

Of the total, 116 people had tremors associated with Parkinson's disease and 67 people had essential tremors. None of their tremors could be controlled with medication.

An average of seven years after treatment, 84% of people had "significant or complete resolution" of tremors, Mark says.

The findings were presented at the annual meeting of the American Society for Radiation Oncology.

Mark says the results compare favorably with those obtained using the two other methods most commonly used to treat tremors that aren’t helped by medication -- deep brain stimulation, in which electrodes are surgically implanted in the brain, and radiofrequency ablation, which uses intense heat to burn tissue away.

But the gamma knife appears to be safer, he says. Only three people, or 1.5%, experienced serious side effects, all in the form of brain swelling that can lead to partial paralysis. All three were treated successfully.

In contrast, about 3% of people treated with deep brain stimulation experience brain bleeding and 5% of those treated with radiofrequency ablation develop serious infections, Mark says.

"None of our patients had hemorrhage or infection. Many patients tell us they prefer the gamma knife because of the favorable results and the fact that there is no incision," he says.

Iris C. Gibbs, MD, a radiation oncologist at Stanford University who is familiar with the technique, tells WebMD that the study "is excellent, offering confidence that this approach can be used for some patients."

But she cautions that patients need to make sure they are treated at medical centers whose doctors have experience with the technique.

"You need a collaborative group of specialists who understand the brain anatomy and the range of choices patients have," Gibbs says.

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51st Annual Meeting of the American Society for Radiation Oncology, Chicago, Nov. 1-5, 2009.

Rufus Mark, MD, Joe Arrington Cancer Center, Texas Tech University, Lubbock, Texas.

Iris C. Gibbs, MD, associate professor, radiation oncology, Stanford University.

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