Overview
Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterized by the loss of neuronal dopamine production in the brain, causing motor and non-motor symptoms.
Deep brain stimulation (DBS) was first used in the 1970s for the treatment of chronic pain. Mixed results and poor electrode design caused a cessation of significant activity in this field in the 1980s, but over the ensuing 25 years, DBS has become a safe and effective treatment for advanced movement disorders, including PD when symptoms are no longer managed adequately with medications.
DBS is currently approved by the US Food and Drug Administration for PD and essential tremor, as well as a humanitarian device exception for dystonia and obsessive-compulsive disorder. DBS is used for patients with PD of at least 4 years’ duration and 4 months of motor complications, and can improve tremor, rigidity, slowness of movement, and drug-induced dyskinesias.
DBS, a form of stereotactic surgery, has become the surgical procedure of choice for Parkinson disease (PD) because it does not involve destruction of brain tissue; it is reversible and can be adjusted as the disease progresses or adverse events occur. Bilateral DBS can be performed without a significant increase in adverse events.
Continued refinement of the knowledge of basal ganglia circuitry and PD pathophysiology of movement disorders has narrowed DBS surgery to 3 key gray matter structures: subthalamic nucleus (STN), pars interna of the globus pallidus (GPi), and intermediate thalamus (VIM) in the thalamus.
The STN and GPi are the preferred two targets for using DBS to treat PD, but VIM can also be utilized when tremor is the primary symptom.
There are evidences in the literature demonstrating the benefit of DBS for treatment of PD. Studies have showed that DBS plus best medical therapy is superior to best medical therapy alone for advanced PD in controlling motor symptoms and improving quality of life.
Moreover, a meta-analysis of randomized controlled trials of DBS in 1184 patients with PD showed that DBS significantly improves patients’ symptoms, functionality, and quality of life, in addition to the reduction of the required medication dose and its associated complications.
It has also been reported that the DBS benefits can be maintained for more than 10 years.
The long-term outcomes of DBS of GPi and STN for patients with PD were reported in a multicenter randomized controlled trial.
The results showed motor function improved between baseline and 36 months for GPi (41.1 to 27.1) and STN (42.5 to 29.7). Health-related quality of life improved at 6 months on all subscales, but improvement diminished over time. It is concluded that the beneficial effect of DBS on motor function was stable and comparable by target over 36 months.
Guidelines have been developed to help neurologists and general physicians identify PD patients who may benefit from referral to a specialized DBS team; these teams assess the likely benefits and risks of DBS for each referred patient.