Pallidotomy dramatically reduces symptoms
in appropriate Parkinson’s patients

BOSTON — June 12, 1998 — Pallidotomy, a surgical procedure designed to reduce symptoms of Parkinson’s disease, can produce a dramatic improvement in the quality of life for selected patients, says G. Rees Cosgrove, MD, a neurosurgeon at the Movement Disorders Center of the Massachusetts General Hospital (MGH). Speaking today at "Brain and Psyche 1998," a press seminar in Boston sponsored by the MGH, the Whitehead Institute and McLean Hospital, Cosgrove presented long-term results from the first five years of pallidotomy treatment at the hospital.

"Overall, neurologists evaluating our patients according to the Clinical Global Improvement Scale (CGIS) – a standard rating of Parkinson’s symptoms – classified 65 to 70 percent as having a good to excellent result," Cosgrove said. He also stressed that careful patient selection is crucial to identifying which individuals are most likely to benefit from the procedure. While the operation is most effective in reducing tremor and uncontrolled movements called dyskinesias that are a side-effect of medication, it is less useful in treating such symptoms as freezing and problems with walking and balance.

Parkinson’s is a progressive, degenerative disorder in which cells in a portion of the brain called the substantia nigra die, resulting in a serious deficiency in production of the neurotransmitter dopamine. Symptoms of Parkinson’s include tremor, rigidity or stiffness, difficulty walking or maintaining balance, and slowness of motion. Since the early 1960s, the primary treatment for Parkinson’s has been with drugs that restore the missing dopamine. After years of drug treatment, however, many patients develop a medication side-effect called dyskinesia, characterized by involuntary movements that can become as disabling as the original symptoms. Such patients may develop what are called "off/on fluctuations," in which they are either "off," totally immobilized by

Parkinson’s symptoms, or "on," uncontrollably moving because of dyskinesia – with no in-between periods of reasonably controlled movement.

Pallidotomy and a similar operation called thalamotomy were widely used to alleviate Parkinson’s symptoms in the 1940s and ’50s but fell into disuse after drug treatments were introduced in the ’60s. Pallidotomy was reintroduced in Europe in the late 1980s for patients with serious dyskinesia, and now is offered at several centers in the U.S. The MGH team began offering the procedure in 1993 and has completed more than 100 operations in about 85 patients.

In pallidotomy, a neurosurgeon creates a tiny lesion in a structure deep within the brain called the globus pallidus. Stereotactic surgical techniques, in which the patient’s head is immobilized in a metal frame, and advanced imaging scans to pinpoint the location of the globus pallidus allow precise placement of the lesion for the best results with a minimal chance of complications. While the mechanism by which the procedure works is still unknown, it is thought that it may partially restore the balance between competing neurochemical control systems in the brain.

In patients having the procedure at the MGH, Cosgrove said, there has been an overall improvement of about 30 percent in motor abilities, according to the CGIS. Dyskinesias are almost completely abolished on the side of the body opposite where the lesion is created. (Because pallidotomy’s effects generally are seen only on one side of the body, some patients may have a second procedure done on the opposite side of the brain.) In most patients, there also is a dramatic improvement in tremor symptoms.

Improved understanding of the specific symptoms alleviated by pallidotomy allows identification of those patients most likely to benefit from the procedure. "The ideal candidates are those who developed Parkinson’s symptoms at a relatively young age – during their 30s or 40s – have serious drug-induced dyskinesias, and frequent ‘on-off’ periods," Cosgrove explained. "It’s important that prospective patients be thoroughly evaluated by an experienced, multidisciplinary team to confirm that they are appropriate for the procedure."

He also stressed that pallidotomy does not produce a cure for Parkinson’s but a temporary improvement of symptoms. "Most of our patients tell us it’s like turning the clock back four or five years, something for which they’re very grateful. We know the disease will continue to progress and their symptoms will get worse again, although at this point we can’t predict how long that will take. But until we have a cure for Parkinson’s disease, this gives us a way to dramatically improve the quality of life in a group of people who would otherwise be totally disabled."

Contact Sue McGreevey in the MGH Public Affairs Office.

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