New screening tool prevents wrong patients from receiving Parkinson's surgery

Aug 9 2004

The allure of a new brain surgery technique to relieve the stiffness and shaking caused by Parkinson’s disease may lead to unnecessary operations, University of Florida researchers say, but a new screening tool they developed could prevent potentially dangerous procedures.

Researchers and clinicians affiliated with UF’s McKnight Brain Institute described in a recent issue of Neurology the first standardized method to help doctors triage patients who have the best chance to be helped by a promising treatment called deep brain stimulation.

“We all know this can be a dramatic therapy for patients, but we want the right type of patients to get the surgery because they are the only ones who are going to do well with it,” said Dr. Michael Okun, co-director of the UF Movement Disorders Center and a neurologist with the College of Medicine. “When you have so many centers doing the operation so rapidly after FDA approval, then you’re going to end up with a lot of patients who might not do well with the therapy or who could do worse.”

Since the Food and Drug Administration approved the treatment in 2002, about 25,000 patients have received deep brain stimulation to treat tremors and movement problems associated with Parkinson’s disease. About a half million Americans have Parkinson’s disease, and 50,000 new cases are diagnosed each year, according to the National Institute for Neurological Disorders and Stroke.

The surgery involves the implantation of small electrodes within the thalamus, subthalamus or globus pallidus, all structures deep in the brain. But the surgery only relieves Parkinson’s symptoms in a handful of patients who meet an array of requirements, among them good response to the drug levodopa, commonly prescribed to treat Parkinson’s disease. Of the first 174 patients referred to the UF Movement Disorders Center for evaluation for deep brain stimulation surgery, only eight would have benefited from the surgery, Okun said.

“Patients have come into our practice who have already received implants who would have never received this therapy if they had been screened properly,” Okun said. “Some of them even had diagnoses other than Parkinson’s disease. We realized all the doctors sending patients our way were trying to get the best possible care for their patients, but they didn’t have the information to evaluate candidates.”

As a result, Okun, in collaboration with UF Movement Disorder Center co-directors Drs. Kelly Foote, a neurosurgeon, and Hubert Fernandez, a neurologist, developed the Florida Surgical Questionnaire for Parkinson’s Disease, a five-section triage tool to help general neurologists and health-care professionals who see the vast majority of patients with Parkinson-like symptoms better determine which may benefit from the surgery.

Practitioners can use the assessment to confirm the initial diagnosis of Parkinson’s disease and take into account patient characteristics, information about the patient’s response to medications and factors that would make surgery inadvisable. It doesn’t replace a full interdisciplinary medical examination for Parkinson’s disease, Okun says, but it is a starting point.

And there’s hope for those whose first-time assessments may not indicate they are appropriate candidates to receive the surgery.

“Maybe a medical optimization score isn’t high enough the first time, but a patient can receive therapy so that in six months, or a year, or even later they become a candidate for the surgery,” Okun said.

In addition to the patients evaluated for deep brain stimulation procedures at UF, the questionnaire helped accurately pinpoint surgery candidates in a retrospective review of 55 patients at movement disorder medical centers at the University of Kansas and Brown University, and at Beth Israel Deaconess Medical Center at Harvard Medical School.

Good candidates for surgery tend to be without any cognitive problems or confusion related to Parkinson’s, under 80 and healthy - aside from their Parkinson’s symptoms. Generally, their disabling tremors cannot be controlled by medication, but they respond to levodopa, a drug that stimulates the production of the chemical messenger dopamine in the brain. Levodopa may cause side effects in some patients called on-off fluctuations, and these patients tend to be good candidates, Okun said.

“Ten times as many people who think they want this surgery won’t be helped by it,” said Dr. James Halsey, a clinical professor of neurology at the University of Alabama at Birmingham School of Medicine. “This is a useful screening tool for physicians who want to refer patients for deep brain stimulation. Physicians all want their helpless patients to be helped, but this treatment works well for some, doesn’t work for many and hurts a few. It (assessment) will also help patients decide whether it’s worth it to sit through a waiting list of four to six months, then to travel 200 or 2,000 miles, only to be disappointed.”