SURGERY FOR PARKINSON'S DISEASE

In 1961, neurosurgeon Irving Cooper published an authoritative monograph titled "Parkinsonism: Its Medical and Surgical Therapy." It devoted 2 of its 237 pages to medical therapy. The rest of the book was described neurosurgical procedures designed to alleviate intractable symptoms of advanced Parkinson’s disease (PD).

The almost magical effects of the drug levodopa, first successfully used by Dr. George Cotzias in 1967, pushed surgery into the background. In recent years however, neurosurgery has reestablished itself as an important strategy in treating advanced PD. Surgery does not cure the disease, however, it is a way of setting the clock back on the disease.

There are three main types of surgery:

• Deep Brain Stimulation (DBS)
• Transplantation
• Lesioning

Deep Brain Stimulation (DBS) involves placing an electrode in the brain to deliver continuous high-frequency electrical stimulation to various parts of the brain that control movement: thalamus, globus pallidus, or the subthalamic nucleus. This stimulation is thought to suppress overactivity in these areas and returns them closer to normal, although the exact mechanism of the DBSeffect is still not fully undersood. DBS can be performed on both sides of the brain. The effect of the DBS technique depends on the target area in the brain.

• DBS of the thalamus is useful for disabling tremor, especially if the tremor is most prominent on only one side of the body. Tremor may not be eliminated completely and may continue to cause some disability.
• DBS of the globus pallidus is useful in reducing dyskinesias (inability to control movements).. Like pallidotomy (described below), it also helps tremor, rigidity and bradykinesia (slowness of movements) to some extent.
• DBS of the subthalamic nucleus offers the greatest promise in reducing symptoms and may be the best target for this technique. It helps reduce most symptoms of Parkinson's disease, including bradykinesia, tremor, and rigidity. Many patients also report a reduced need for medications after surgery, although complete elimination is rare.

Transplantation techniques are experimental. They involve placement of embryonic dopamine tissue in the putamen. The first double-blind placebo-controlled trial of fetal graft transplantation surgery for advanced Parkinson's disease was reported in 2001. The study followed 40 patients with advanced Parkinson's disease. Fetal transplants resulted in modest improvement for younger patients in rigidity and bradykinesia. However, there was a risk of unpredictable and disabling dyskinesias. Older patients, 60 years or older, did not show significant benefit.

Lesioning involves destruction of a part of the brain that has become overactive or is functioning abnormally due to Parkninson's disease. In general, these procedures have been replaced by Deep Brain Stimulation (see above). Lesioning of the thalamus is called thalamotomy. Thalamotomy helps reduce tremor on the side of the body opposite to the surgical lesion. Lesioning of the globus pallidus is called pallidotomy. Pallidotomy has the greatest effect in reducing dyskinesias. It also helps tremor, rigidity and bradykinesia to some extent.

A more complete description of these surgical techniques is available in an article written by Dr. Penn, Professor of Neurosurgery at the University of Chicago Medical Center. Dr. Penn performs surgery for PD.