Parkinson's disease is a progressive neurological condition that affects movement. There are four main characteristics. Tremor is trembling, usually in the hand, but sometimes seen in a foot, jaw or head. The tremor is most noticeable when the limb is at rest or during periods of stress. Rigidity is a stiffness in the hands, arms, legs, jaw or head. Bradykinesia is slowed movement, or slowness in the initiation of movement. Postural instability is an impairment of balance, which increases the risk of falls.

The National Parkinson Foundation estimates 1.5 million Americans have Parkinson's disease. About 60,000 more people are diagnosed with the condition each year. Men and women are affected equally. Most cases occur after 60. However, about 15 percent of patients develop signs before 50.

Parkinson's disease occurs when certain nerve cells in an area of the brain, called the substantia nigra, stop working and begin to die. These nerve cells normally produce the chemical, dopamine, which brain cells controlling movement need to communicate. As these nerve cells die off, there is less dopamine available in the brain, causing abnormal communication signals and impaired movement. By the time patients develop symptoms they have lost 60 to 80 percent of their dopamine-producing cells.

Treating Parkinson's Disease

There is no cure for Parkinson's disease. But medication and surgery can often ease symptoms. Levodopa (L-dopa) is a drug that nerve cells can use to make dopamine. However, the medication doesn't readily cross the blood-brain barrier. So doctors most commonly prescribe dopamine precursors, medications that can be converted into dopamine in the brain. Levodopa can be very effective in treating some of the symptoms of Parkinson's disease - especially in the early stages of the disease. However, the drug can't replace lost nerve cells or stop progression of Parkinson's disease. Eventually, patients may develop fluctuating response to levodopa.

Deep Brain Stimulation for Parkinson's

Another treatment option for some patients is deep brain stimulation (DBS). DBS uses surgically implanted electrodes connected by wires to an implantable neurostimulator. The neurostimulator delivers controlled pulses of electricity to the electrodes into the target area of the brain. The impulses block electrical signals causing the abnormal movements.

DBS targets one of three areas in the brain. When placed in the thalamus, the treatment reduces only tremor. In the globus pallidus or the subthalamic nucleus, DBS can reduce tremor, rigidity, bradykinesia and/or gait problems.

DBS is a very effective treatment for some patients. It can reduce the need for medication and control the incidence of symptoms. But it doesn't work for everyone. Researchers say DBS is best for people who have had a good response to medication and are otherwise in good health. There are some risks associated with the surgery - most notably bleeding (which can lead to a stroke, occurring in about two percent of patients) and infection (affecting 4 percent of patients).

DBS for Early Stage Parkinson's Disease

The National Parkinson Foundation says patients typically have had the disease for at least five years before they are considered for brain stimulation. Now, researchers at Vanderbilt University want to find out if DBS can be useful in early stages of Parkinson's, when symptoms are still very mild.

David Charles, M.D., a Neurologist with Vanderbilt University Medical Center, says the FDA has issued an investigational device exemption to enable doctors to perform a small pilot study of DBS in 30 patients with early stage Parkinson's. Half the participants will receive the surgery plus medication; the other half will get only medication. Patients will be followed for two or more years and their symptoms and outcomes will be compared.

Just recently, French researchers announced their results of DBS for a group of 20 Parkinson's patients with early-stage disease. After 18 months, daily medication dose in those receiving surgery was reduced by 59 percent. Severity of symptoms during "off medication" periods decreased by 69 percent and levodopa-induced motor complications decreased by 83 percent. On the other hand, patients who only received medication (no surgery) had a 12 percent increase in medication dose, 29 percent increase in symptoms during "off medication" times and a 15 percent increase in motor complications.

Vanderbilt University is the only site in the U.S. conducting the DBS trial for early stage Parkinson's. However, they are accepting study participants from around the world. For information, call (615) 936-8225, or log onto the study website at http://www.vanderbiltdbs.com.

For information about the trial, call (615) 936-8225, or log onto the study website at http://www.vanderbiltdbs.com. Information is also available by logging onto: http://www.clinicaltrials.gov. In the search box, type in the study identification number: NCT00282152.

For general information on Parkinson's Disease or deep brain stimulation:

American Parkinson Disease Association, Inc.

National Institute of Neurological Disorders and Stroke

National Parkinson Foundation

Parkinson's Disease Foundation

We Move (Worldwide Education and Awareness for Movement Disorders)

Information about deep brain stimulation is also available from Medtronic at:

http://www.medtronic.com/neuro/parkinsons/activa_qa2.html