Deep brain stimulation offers hope for Parkinson's patients

Deep brain stimulation, a minimally invasive, high frequency in stimulation therapy, offers hope for patients suffering from Parkinson's disease, Dystonia, a muscular movement disorder, and essential tremors, a team of leading neurosurgeons of Chennai said on Tuesday.

Addressing a press conference, Dr. S Yogaraj, Consultant Neurologist with Apollo Hospitals said: “Those suffering from advanced stages of Parkinson's disease can now have electrode implants in the brain through a pacemaker to stimulate the neurons through mild current".

The disease occurs when cells in the substantia nigra region die, depriving the brain of a chemical called dopamine--a neuro-transmitter that keeps alive communication among brain cells.

Dr. Yogaraj and fellow consultant at the hospital, Dr. B. Chendilnathan, who are trained specially in these procedures from the University of Kiel, Germany and Netherlands, said Deep brain stimulation (DBS) is used to treat a variety of disabling neurological symptoms—most commonly the disabling symptoms of Parkinson’s disease such as tremor, rigidity, stiffness, slowed movement, and walking problems. The procedure is also used to treat essential tremor and Dystonia.

At present, the procedure is used only for patients whose symptoms cannot be adequately controlled with medications and those who desire a better quality of life.

DBS uses a surgically implanted, battery-operated medical device called a neuro-stimulator, similar to a heart pacemaker and approximately the size of a stopwatch, to deliver electrical stimulation to targeted areas in the brain that control movement. It blocks the abnormal nerve signals that cause tremor and PD symptoms.

Before the procedure, a neurosurgeon uses magnetic resonance imaging (MRI) or computed tomography (CT) scanning to identify and locate the exact target within the brain where electrical nerve signals generate the Parkinson's Disease symptoms.

The doctors said:" We use micro-electrode recording, which involves a small wire that monitors the activity of nerve cells in the target area, to more specifically identify the precise brain target that will be stimulated. We do a recording with five channels so that we have enough options to select the best channel to place the permanent lead.

Once the target is located, an electrode is inserted through a small opening in the skull and implanted in the brain. The tip of the electrode is positioned within the targeted brain area.

An insulated wire is passed under the skin of the head, neck, and shoulder, connecting the electrode to the neuro-stimulator. The neuro-stimulator (the "battery pack") is the third component and is usually implanted under the skin near the collarbone. In some cases it may be implanted lower in the chest or under the skin over the abdomen.

Generally the battery or the Pacemaker lasts for around five years, depending on the voltage to which the patient responds.

Once the battery expires, the old pacemaker will have to be replaced through another small surgery. Now there are rechargeable pacemakers available in the market with an average life of nine to ten years.

“Once the system is in place, electrical impulses are sent from the neuro stimulator into the brain. These impulses interfere with and block the electrical signals that cause PD symptoms” says Dr. B. Chendilnathan.

Unlike previous surgeries for Parkinson's disease, DBS does not damage healthy brain tissue by destroying nerve cells. Instead, the procedure blocks electrical signals from targeted areas in the brain. In other words, DBS does not cause any permanent damage to the brain and is a reversible procedure. Also, stimulation from the neuro-stimulator is easily adjustable without further surgery through telemetry, a handheld programmer that is placed on the battery over the skin and by exchange of radio frequency signals. Generally there would be a 50 per cent or more drop in drug intake after the procedure, depending on the individuals.

The reduction in dose of medication leads to a significant improvement in side effects such as dyskinesias (involuntary movements caused by long-term use of levodopa). In some cases, the stimulation itself can suppress dyskinesias without a reduction in medication.

Many think that oral drug is the only option to manage Parkinson’s disease. Deep Brain Stimulation has changed the scenario.

Deep brain stimulation modifies symptoms of disease, but does not stop the progress of the disease.

The cost of the surgery is high due to intense technological inputs. "We are working on bringing down the cost", the two doctors said.

- Asian Tribune -