Deep Brain Stimulation

Photo courtesy of Medtronic, Inc Brain pacemaker: Similar to a cardiac pacemaker, this one sends electrical impulses to electrodes in the brain.

In the case of Parkinson's disease, DBS stops the overactivity that causes muscle tremors and stiffness of limbs. These symptoms are caused by a lack of the neurotransmitter dopamine in the brain. Cells of the substantia nigra - an area of the brain just above the brain stem - normally make dopamine but Parkinson's causes these cells to die, resulting in a lack of dopamine. Since dopamine helps to regulate areas of the brain that control movement, like the thalamus, subthalamic nucleus and the globus pallidus, a lack of it causes some of these areas to go into overdrive. By targeting these areas, DBS can block the unwanted nerve traffic.

It may sound like a miracle treatment, but DBS does involve major surgery. Most seriously, any brain surgery carries a risk of cerebral haemorrhage - bleeding on the brain - and the impairment of other brain functions like speech and vision. With DBS surgery, there is the added possibility of the implant dislodging or becoming infected, the patient simply not responding to the treatment and the need to undergo further surgery to replace the pacemaker about every four years when the battery runs out.

In terms of post-operative care, it can sometimes be hard to find an electrical impulse with the right frequency and voltage for the patient. And although DBS may permanently remove the symptoms of Parkinson's, it also ties the patient to permanent aftercare.

There are other options for Parkinson's sufferers but these also have their drawbacks. Lesional surgery, in which the overactive areas of the brain are burned or cut, cannot be used for all patients since some areas of the brain are too sensitive to be treated in this manner. Drugs, many of which mimic the effects of dopamine, can also be used and are a successful treatment for some patients, though they can lose their effectiveness over time. Some patients suffer side effects from drugs such as involuntary movements, nausea, hallucinations and irregular heartbeat depending on the class of drug being taken. About one in five patients do not respond to drugs at all, and these are the patients most likely to be considered for DBS.