Deep Brain Stimulation or DBS refers to a surgical procedure that implants an electronic stimulator deep into the brain in order to treat motor complications of levodopa therapy. These complications are called dyskineasia and involve painful, involuntary and spasmodic movements of the hands, trunk and legs. Dyskinesias may develop in some persons with Parkinson's disease (PD) after years of treatment with levodopa. While most cases of dyskinesia can be treated by adjusting medications, such adjustments eventually fail to improve symptoms. That is when surgical options might help.
DBS involves implanting an electrical stimulator into either the subthalamic nucleus (STN) or a section of the Globus Pallidus (GPi). These brain sites normally play crucial roles in regulating movement. Thus, we can use a 'neurostimulator' -- a battery-operated medical device the size of a stopwatch. It is usually implanted under the skin near the collarbone, with a wire going to the brain to oversee the brain regions that regulate movement.
The Pros of Deep Brain Stimulation Include:
- Striking improvement of symptoms related to levodopa side effects, particularly with respect to dyskinesia, for most persons who undergo the procedure
- No ‘lesions’ or damage to the brain itself is incurred
- The patient himself controls the level of stimulation, thus allowing adjustment based on subjective need. Both DBS–STN and DBS–GPi seem to provide comparable benefits, though GPi seems to be associated with fewer side effects. Clinical trials that directly compare effects of stimulation of these two targets are now being performed and results should be available in 2009.
The Cons of Deep Brain Stimulation
DBS procedures carry some risks. After all, it is a surgical procedure involving cutting open the scalp and implanting a device deep into the brain. Some ‘cons’ of DBS include:
- DBS does not appear to improve “on" functions beyond what can be achieved with levodopa alone. That is, its benefits largely have to do with eliminating dyskinesia rather than with improving primary PD symptoms.
- Side effects can occur in relation to the surgical procedure, the stimulation system, stimulation itself, and the periodic need to replace the battery.
Bottom line: If you are having painful and uncontrollable dyskinesias, talk to your doctor about DBS and alternatives to DBS. Studies show that most people with severe dyskinesias can benefit from adjusting their medication ‘delivery system’ from oral doses of levodopa to ‘continuous delivery systems’ such as infusions into the stomach. But when a continuous delivery system is not an option, DBS may work.
The scientific and clinical basis for the treatment of Parkinson disease (2009). Olanow CW, Stern MB, Sethi K. Neurology. 2009 May 26;72(21 Suppl 4):S1-136. Review.