Deep Brain Stimulation (DBS) for Parkinson’s Disease
Most common symptoms of Parkinson’s Disease (PD) are tremors, slowness of body movements, rigidity of body and postural disturbances. Since PD is a neurodegenerative disease, it means that the disease slowly progresses and patient’s condition worsens over time. There is no cure for PD so far. The treatment given to patients only reduces the symptoms and makes life a little easier.
There are several medicines available for PD, each with its own problems. It is also seen that after taking medicines for several years, the response to the medicine does not give relief from symptoms for an entire day and some patients feel as if the effect of these medicines wane off in 2-3 hours, requiring frequent dosage of medicines.
In some patients, some bizarre movements appear such as restlessness or aggression in movements of limbs or trunk. These are Dyskinesia
(Dys = abnormal, Kinesia = movements). Once these develop, it becomes difficult to manage them, still keeping the patients active. It is at this time that we have a saviour in the form of Deep Brain Stimulation (DBS) operation. It is called DBS because deep structures in brain are stimulated with the help of fine wires connected to a pulse generator,
which contains a battery stimulating these areas in the brain.
This operation is done in two stages. In the first stage, the patient remains conscious and MRI of brain is done to locate the deep brain structure which is to be stimulated. It also oversees what the route of the stimulating electrodes will be and that there are no major blood vessels in the route. After that, the exact position of the deep nucleus is calculated and the electrodes are placed in it. The nucleus is stimulated slowly and the patient is assessed simultaneously.
During this period, the patient is awake and does some movements as told. Once the correct position is identified the electrode is left there and its position is fixed. This procedure is repeated on the second side as well. After this, the patient is put under anaesthesia and the wires from both sides are tunnelled under the skin and the pacemaker which generates the stimulation is connected to the wires and placed on the chest under the skin, in a way similar to the heart pacemaker.
The batteries are then programmed according to the needs of the patient. It takes several rounds of programming to calculate the right amount of current to be sent to the brain, which may take 3-6 months. There is one more issue here. There are two types of batteries, one which lasts 2-5 years after which the battery has to be replaced by and for a cost. The other type of battery is rechargeable and it can be charged periodically from outside. The life of this battery is about 10-20 years.
After optimum programming, patients generally feel very good. Their quality of life improves, slowness improves, Dyskinesia disappears and stiffness also reduces. The requirement of dose of medicines also reduces. All this to the tune of 60-70%. It must be remembered that it does not prevent progression of the disease and so regular programming is required, depending on needs of the individual. However, there are some problems which do not improve. These are falling, disorders of gait (walking), speech and memory disturbance and depression. Some patients who develop some features like suspicious nature or hallucinations due to high dosage of medicines also improve after DBS operation, which results in reduction in the dosage of the drugs.
Overall, one can say that DBS has come as a boon to the patients of Parkinson’s disease as it rescues the patients from load of high dosage of medicines, long term reduction of cost of therapy, treating almost all the main symptoms of PD. Tremors usually do not respond very dramatically, though there is still some reduction in tremors as well. In addition, dyskinesia is completely cured and several medicine dependent side-effects like psychosis and hallucinations are also treated. It must be remembered that one should not expect it to cure memory loss, depression, speech problem and falls. These symptoms are not treated by DBS.
Dr. Madhuri Behari