Individuals suffering Parkinson’s disease face a number of debilitating motor skills-related symptoms, including stiffness, tremor, rigidity and slowed movement, that affect daily living. For those whose symptoms cannot be controlled solely by medications, deep brain stimulation has potential to serve as an effective additional treatment.
According to the National Parkinson Foundation, deep brain stimulation (DBS) is a widely used surgical procedure that “blocks electrical signals from targeted areas in the brain.” Because the procedure does not destroy nerve cells, it causes no damage to a patient’s healthy brain tissue.
The procedure process
As part of DBS, patients first receive a computed tomography (CT) or magnetic resonance imaging (MRI) scan so the neurosurgeon can locate where within the brain abnormal nerve signals are generating symptoms. In general, the foundation states, the three targeted areas approved by the U.S. Food and Drug Administration for use in PD patients include the sub-thalamic nucleus, the thalamus and a section of the globus pallidus.
During the DBS procedure, the neurosurgeon then implants a neuro-stimulator – a small medical device about the size of a stopwatch that can be programmed externally – in a patient, usually near the collarbone, chest or abdomen. The other parts of the DBS system include the lead (or electrode), a thin, insulated wire implanted in the brain with the tip positioned in the targeted area, and the extension, an insulated wire that connects the lead and the neuro-stimulator.
The three parts of the DBS system then work together to painlessly stimulate the targeted areas of the brain, delivering finely controlled electrical impulses to block the abnormal nerve signals that cause the PD symptoms.
According to the National Institute of Neurological Disorders and Stroke, “DBS requires careful programming of the stimulator device in order to work correctly.”
Candidates for DBS treatment
Not all PD patients are suitable for DBS treatment. In general, they must have experienced PD symptoms that interfere with daily activities for at least five years. Additionally, the foundation lists the following as necessary characteristics of candidates wanting to receive the procedure:
- Patients have a good response to PD medications – particularly carbidopa/levodopa – even if the response is insufficient.
- Patients have tried various combinations of carbidopa/levodopa and dopamine agonists while supervised by a movement disorders neurologist.
- Patients have tried other medications (tolcapone, entacapone, amantadine or selegiline) without beneficial results.
When either the globus pallidus or the subthalamic nucleus are targeted, patients generally see a reduction in motor-function symptoms such as rigidity, tremor and bradykinesia. Reducing tremor is the primary function of stimulating the thalamus.
The procedure usually doesn’t help with posture, balance, dementia, depression or anxiety and has not been demonstrated as beneficial for “atypical” parkinsonian syndromes, according to research done by the institute.
Prognosis and side effects
In general, many patients who receive DBS experience “considerable reduction of their PD symptoms and are able to greatly reduce their medications,” according to the foundation. By reducing the medication dose, many patients experience a notable decrease of side effects from levodopa, the most common of which is involuntary movements called dyskinesias.
That being said, most patients remain on prescribed medications after undergoing the procedure.
As with any surgical procedure, DBS can lead to potential complications, which include infection, stroke, cranial bleeding, brain hemorrhage or negative reactions to the anesthesia.
Patients are encouraged to discuss the risks associated with DBS with their neurologist, as underlying medical conditions and other issues can be risk factors, the foundation states.