U.S. Okays New Brain Site for PD Surgery

In a step that reflects the importance of surgical procedures in the treatment of advanced Parkinson’s disease, the U.S. Food and Drug Administration (FDA) issued in January a general approval of the use of deep brain stimulation for patients of Parkinson’s disease.

Up to this point, deep brain stimulation was restricted to one brain site, the thalamus, and to stimulation on one side of the brain. It was approved only for the relief of tremors. The procedure is now FDA approved for a wide range of Parkinson’s symptoms and complications, including wearing-off motor fluctuations, episodes of extreme slowness and stiffness caused by a failure of medication, and dyskinesias, or twisting movements caused by excessive medication. The stimulation device can be implanted in additional brain sites on both sides of the brain.

The New England Journal of Medicine study on which the recent FDA action was based was sponsored by Medtronic, the medical technology company that developed the deep brain stimulator. The study was conducted at 18 surgical centers in North America, Europe, and Australia.

The data submitted to the FDA on 117 patients showed that the procedure had safety and effectiveness, improving movement control and mobility in patients with advanced stages of Parkinson’s.

The FDA approval is a welcome development. But surgery is not for everyone, says Blair Ford, M.D., Medical Director of the Center for Movement Disorder Surgery at Columbia-Presbyterian Medical Center in New York City and Scientific Advisor for PDF News & Review. He says that to be eligible for the procedure, a patient should demonstrate: Typical “classical” Parkinson’s disease, defined by the presence of tremor at rest, rigidity, slowness, and postural instability. Patients must still derive a good, even if short-lasting, response to each dose of their antiparkinsonian medications.

1. Disabling parkinsonian symptoms in the “off” state, when their medication effect wears off.
2. Disabling uncontrollable medication-induced movements, called dyskinesias.
3. A good understanding of the potential benefits and risks of the operative procedures and evaluation procedures, and the ability to give informed consent.
4. Good general health.
5. A good emotional support network of family and friends.

By contrast, a patient is not a good candidate if he or she demonstrates:

1. Atypical or rare forms of parkinsonism, such as progressive supranuclear palsy (PSP), multiple system atrophy (MSA), or corticobasoganglionic degeneration (CBGD); or a known acquired cause of parkinsonism, such as stroke or brain trauma.
2. Failure to experience any benefit from antiparkinsonian medication.
3. Severe memory loss, confusion, hallucinations, or apathy. In fact, patients with these problems may get worse as a result of brain surgery.
4. Severe chronic psychiatric disorder, such as psychosis, depression, bipolar disorder, alcoholism, or a personality disorder.
5. Inability to understand the potential benefits and risks of the operative procedures, or to give informed consent.
6. Significant medical problems that would unacceptably increase the surgical risk, such as cancer or serious heart disease.

Age, Dr. Ford added, is not necessarily a criterion for deep brain surgery or other forms of neurosurgery. An otherwise healthy older patient with PD can safely undergo and benefit from this type of surgery. On the other hand, while age is not an exclusion criterion, the best results are obtained in younger patients.

Dr. Ford emphasized the importance of recognizing that some symptoms of PD respond better to surgery than others. The effect of surgery on slowness and stiffness can be generally predicted from the response to medication.

Some patients, he said, have an excellent response to levodopa and other medications, with almost complete suppression of parkinsonism, but suffer from spells of wearing off, during which they become stiff, immobile, and frozen. These individuals should do well with surgery.

Other patients, he added, have an incomplete response to levodopa. Even when experiencing their maximal medication effect, they have some gait or balance or speech impairment. These patients will not do as well with surgery. They will probably experience relief only of the symptoms that their medication helps.

The exception to the medication response rule, in Dr. Ford’s opinion, is the patient who experiences severe tremors that are resistant to medication. Surgery can generally reduce even the most severe tremor, regardless of whether levodopa can help this symptom. Therefore, patients with severe tremors may anticipate relief from surgery even if their antiparkinsonian medication is not effective for tremor.