Parkinson’s disease is a progressive disorder that affects movement and coordination. It occurs when nerve cells that produce dopamine — which works with other neurotransmitters to coordinate movement. The most common symptoms are trembling in the hands, arms, legs, and jaw; rigidity or stiffness of the limbs; slowness of movement; and impaired balance and coordination.
The primary treatment of Parkinson’s is the use of medication to control symptoms. As the disease progresses, surgery may be considered to relieve the involuntary movements. By operating on the deep brain structures involved in motion control — the thalamus, globus pallidus and subthalamic nucleus — a neurosurgeon may help relieve Parkinson’s symptoms.
There are three basic types of surgery:
Pallidotomy is performed by inserting a wire probe into the globus pallidus, which is thought to become hyperactive in Parkinson’s patients due to the loss of dopamine. This can help restore the balance that normal movement requires.
Thalamotomy uses radiofrequency energy currents to destroy a small, but specific portion of the thalamus. This may benefit patients with disabling tremors in the hand or arm, but it does not relieve other.
The Deep Brain Stimulation (DBS) offers a safer alternative to pallidotomy and thalamotomy. It uses small electrodes which are implanted to provide an electrical impulse to either the subthalamic nucleus of the thalamus or the globus pallidus. Implantation of the electrode is guided through magnetic resonance imaging (MRI) and neurophysiological mapping, to pinpoint the correct location. The electrode is connected to wires that lead to an impulse generator or IPG (similar to a pacemaker) that is placed under the collarbone and beneath the skin. Patients have a controller, which allows them to turn the device on or off. The electrodes are usually placed on one side of the brain. An electrode implanted in the left side of the brain will control the symptoms on the right side of the body and vice versa. Some patients may need to have stimulators implanted on both sides of the brain.
This form of stimulation helps rebalance the control messages in the brain, thereby suppressing tremor. DBS of the subthalamic nucleus or globus pallidus may be effective in treating all of the primary motor features of Parkinson’s, and may allow for significant decreases in medication doses. For more information, visit www.parkinson.org.