Penn Medicine clinicians have a long history as leaders in deep brain stimulation (DBS) for movement disorders such as Parkinson's disease (PD) and Essential Tremor.
The management of PD typically begins with medications, primarily carbidopa-levodopa, to which an array of agents is added, as needed, over time. Like levodopa, these drugs either enhance the activity of dopamine in the brain, or act as adjuncts to drugs in the management profile. All of these medications wax and wane in efficacy over time, and all are attended by unpleasant side effects that further complicate the disease course and quality of life for individuals with PD. Eventually, for many patients, medications become intolerable due to side effects such as dyskinesias, or have variable effect ("motor fluctuations"), at which point other interventions, including DBS, become options for treatment.
DBS has been a part of the treatment paradigm at Penn Medicine for more than a decade, where it is now a treatment of choice for otherwise healthy patients with advanced PD. DBS involves the placement of electrodes in the thalamus, pallidum and subthalamic nucleus (STN) to treat the specific symptoms of PD. In the STN, DBS is an efficacious treatment for a range of symptoms in PD, including tremor, rigidity and dyskinesia, and the STN can be beneficial target for DBS when medication reduction is one of the goals of treatment. At Penn Medicine, candidates for DBS include patients in relatively good health with levodopa responsiveness, the presence of tremor, bradykinesia and/or rigidity, frequent on-off motor fluctuations, and decreased functional on-times.
Certain restrictions apply to the application of DBS, and it is not an appropriate approach for all individuals with PD. In addition, DBS for PD is generally available only at centers with the capacity to offer dedicated multidisciplinary teams of movement disorder neurologists, functional neurosurgeons, and specialized support staff.
About Parkinson's Disease
Parkinson's disease (PD) is an incurable, progressive neurodegenerative disorder that affects the basal ganglia and the substantia nigra (SN) of the deep brain; the SN is associated with production of the neurotransmitter dopamine. The progression of PD induces an attenuation of the dopamine-producing cells of the SN, resulting in erratic stimulation of the subthalamic nucleus (STN) of the basal ganglia and subsequent interruption of the globus pallidus interna (GPi). These events, in turn, bring about an array of motor symptoms, including tremor, bradykinesia, and rigidity. Eventually, these symptoms are joined by fatigue and other nonmotor issues.
Case Study
CW is a 59-year-old man with an 11-year history of Parkinson's disease first diagnosed after he began to have right-hand tremor and problems with dexterity. His symptoms were initially well controlled with medications, but over the last year, he began to experience unpredictable motor fluctuations despite increasing doses of medication.
As he increased the frequency of medication doses, CW noticed unwanted movements of his body and hands that were worse just after taking the medication. He also started to develop painful cramping in his right leg when medications were starting to work. Overall, CW felt that medications kept him in his best "ON" state about 50% of the day.
Because of these symptoms, Dr. Andres Deik, his Penn Medicine neurologist, discussed with CW the potential role of deep brain stimulation in increasing his best "ON" time, decreasing motor fluctuations, reducing dyskinesias, and potentially lowering medication doses.
Subsequently, CW had a thorough evaluation in the deep brain stimulation clinic by Dr. Meredith Spindler where he was found to have a 30% motor response to Sinemet (carbidopa/levodopa) on detailed testing OFF and ON medications. A good response on formal ON-OFF testing has been shown to be predictive of a good response to deep brain stimulation.
CW then underwent neuropsychological testing. Neuropsychological testing is an important part of the evaluation before deep brain stimulation as it can help identify subtle cognitive issues that may arise from Parkinson's disease, and helps inform the selection of the brain target for DBS. After a thorough evaluation, there were no cognitive concerns identified that would preclude deep brain stimulation.
The Movement Disorders DBS team then met to discuss the available information regarding CW. Potential treatment options included MRI-guided focused ultrasound (mg-FUS) thalamotomy, mg-FUS pallidotomy, and deep brain stimulation (DBS). Overall, given his relatively young age, motor fluctuations of advanced Parkinson's disease, and dose-dependent side effects, it was felt that CW would be a candidate for STN DBS, with the goal of decreasing his medication dosing and prolonging his best ON time.
Discussion focused upon the possibility of the GPi as a target to minimize the risk of worsening speech, since this side effect has never been reported with GPi. However, given CW's dose-dependent side effects and goal to decrease medications, the STN would be the most appropriate target. No concerns regarding bilateral surgery were raised from either the neuropsychological evaluation or DBS conference.
CW then saw neurosurgeon Dr. Iahn Cajigas who discussed the consensus from the team with him. He then decided to proceed with DBS.
The surgery was performed in two stages. First, CW had bilateral STN DBS electrodes placed. This surgery was performed while he was awake for short periods to confirm the benefit of DBS and test for any side effects. Additionally, special micro-electrode recordings were used to map the physiological boundaries of the STN and to guide the final position of the DBS electrodes (Figure 1). After surgery, CW obtained a high resolution CT. This information was used to determine the final orientation of the brain electrodes, and later used to guide DBS programming.
Figure 1: Views along the right sided DBS electrode superimposed on CW's MRI demonstrate location of the electrode with the dorsolateral STN. B) 3D view of the DBS electrodes relative to the STN and substantia nigra.
CW was discharged home the morning after surgery. He returned 10 days later for a short outpatient procedure to connect of the leads to a small pulse generator/battery placed subcutaneously just below his clavicle. A few weeks later, he met with Dr. Deik for initial programming of his DBS system.
Six months post-surgery, CW reports that he no longer experiences motor fluctuations and has been able to cut his Sinemet dose by more than 50%. Since decreasing the medication doses, he has not experienced any more dyskinesias.
About Deep Brain Stimulation at Penn Medicine
As one of the largest treatment programs for DBS in the United States, more than 1,200 DBS procedures have been performed at Penn Medicine. Our neurosurgery team consisting of Dr. Casey Halpern, Dr. H. Isaac Chen, and Dr. Iahn Cajigas, perform about five DBS procedures per week. Through robust research and high-volume expertise, Penn Medicine continues to expand the understanding and use of DBS therapy.
Refer a Patient
We understand that some providers only want a short-term surgical partner, while others seek a long-term care team for their patient. At Penn, we offer any component of our expertise in whatever capacity needed.
Call the 24/7 provider-only line at 877-937-7366 or submit a referral through our secure online referral form.