Parkinson disease is a chronic progressive disease with significant impairment and distress. A host of pharmacological options are available. Unfortunately, drug treatment often is only partially successful in reducing symptoms and can produce problematic adverse events. Deep brain stimulation (DBS) has emerged as a potential therapeutic option for those with severe Parkinson disease. DBS involves a neurosurgical procedure that places an electrode or electrodes into the brain with a device to modulate an electric current. The brain subthalamic nuclei has become the most common site for DBS electrode placement.
Many questions remain unanswered in DBS therapy for Parkinson disease. A recent consensus conference assembled 49 experts in the use and care of patients receiving DBS therapy. They have published their recommendations in a recent manuscript published in Archives of Neurology. I will summarize some of their recommendations:
Surgical Selection: Expert selection of candidates for DBS is viewed as the most important variable in getting a good DBS outcome. Best candidates for DBS include those with the following features:
- Excellent response to the drug levodopa
- Younger age
- No or few axial motor symptoms that do not respond to levodopa
- Limited cognitive impairment
- Limited or well-controlled psychiatric disease
Surgical Complications: Surgical complications are not common but are not trivial and need to be taken into account when considering DBS surgery. Complications can include intracranial hemorrhage (bleeding), stroke, infection, erosion of DBS leads, and death. Advanced age and medical comorbidities appear to increase the risks for surgical complications but should not be absolute contraindications. Surgical team experience is important and patients and their families should select centers with extensive experience with the procedure. There is a need for a standardized system of reporting DBS complications to allow for comparison across treatment sites.
Parkinson Disease Outcome: If a patient has improvement in gait and speech with levodopa, they are more likely to have improvement in these domains with DBS. Initial improvement in gait and speech with DBS may later fade as the disease progresses. Some patients experience increase in depression after DBS and this may be related to the site of the electrodes. Patients need to have depression, anxiety, apathy, psychosis and impulsivity levels assessed before surgery as these parameters may complicate outcome. Improvement in some aspects of Parkinson disease has been demonstrated for up to 5 years. Nevertheless, progression of disease commonly occurs in good DBS repsonders and DBS does not prevent the late stages of Parkinson disease including freezing of gait, postural instability and cognitive decline.
This expert consensus guideline will aid clinicians, patients and family members in considering DBS as a therapeutic option. A patient resource for those with Parkinson disease considering DBS can be found here (DBS-STN.org-an affiliate of the Parkinson Alliance).
Figure of coronal section of brain showing subthalamic nuclei (STN in yellow)--common electrode placement site in DBS for Parkinson disease. Figure courtesy of Creative Commons from Wikipedia, author Andrew Gillies.
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