In 2002, the FDA approved the use of deep brain stimulation (DBS) for patients with Parkinsons disease. Although it isn’t a cure, DBS has been shown to help manage symptoms of the disease. A workshop of experts was recently convened to create a consensus review of key issues involving DBS surgery. Published in the February 2011 Archives of Neurology, the review is designed to assist patients and physicians who are considering DBS based on clinical research and expert opinion.
One of the most important steps toward achieving consistently good outcomes with DBS is careful patient selection. Studies have suggested that more than 30% of failed DBS procedures can be attributed to inappropriate indications for surgery. Patient selection should be based on an individual risk-benefit evaluation for each patient. Good candidates for DBS include patients with Parkinson’s who do not have significant cognitive or psychiatric problems and medically intractable motor fluctuations, intractable tremor, or intolerance of medication adverse effects. DBS has yielded the best results in patients with advanced Parkinson’s and excellent levodopa response, younger age, no or few axial non–levodopa-responsive motor symptoms, no or very mild cognitive impairment, and absence of or well-controlled psychiatric disease.
Experience & Teamwork Matter
The surgical techniques for implanting DBS devices are continuing to evolve, but few studies directly compare the safety or effectiveness of these methods; the best techniques for DBS require more research. However, the workgroup did reach a consensus on the importance of having Parkinson’s patients receive care in expert centers that deliver DBS. A multidisciplinary team is essential; it should involve a movement disorder neurologist, a neurosurgeon, a neuropsychologist, an internist, and in many cases, a psychiatrist. Stimulation programming appears to be best accomplished by a highly trained clinician, but it should be noted that it can take 3 to 6 months to obtain optimal results.
“Patient selection should be based on an individual risk-benefit evaluation for each patient.”
Current data show that surgical complication rates with DBS vary widely. Infection has been the most commonly reported complication, but other surgical complications may occur with lesser frequency. These include intracranial hemorrhage, stroke, lead erosion without infection, lead fracture, lead migration, and death, but it should be noted that the rates vary widely within these complications.
A Look at Efficacy
The literature suggests that DBS improves levodopa responsive symptoms, dyskinesia, and tremor, and these benefits seem to be long-lasting in many motor domains. Long-term improvements have been demonstrated for up to 5 years for both subthalamic nucleus (STN) and globus pallidus pars interna (GPi) DBS, especially on motor fluctuations and for tremor with STN, GPi, and ventral intermediate nucleus of the thalamus DBS. STN DBS can allow patients to use less medication, but may be associated with worsening of non-motor symptoms and falls. STN DBS may also be complicated by depression, apathy, impulsivity, worsened verbal fluency, and executive dysfunction in some patients. Ablative therapy still appears to be an effective alternative, but should be considered only in a select group of patients.
Despite these largely positive results, Parkinson’s disease continues to progress after DBS, and there’s little evidence that surgery alters disease progression. Over time, patients who have the procedure often develop levodopa-resistant symptoms (eg, freezing of gait, postural instability, and cognitive decline). As such, long-term follow-up is essential. Postoperative brain MRIs can be performed safely and appear to be useful in monitoring patients who have received DBS.
Readings & Resources (click to view)
Bronstein JM, Tagliati M, Alterman RL, et al. Deep brain stimulation for Parkinson disease: an expert consensus and review of key issues. Arch Neurol. Published online Oct. 11, 2010. Available at: http://archneur.ama-assn.org/cgi/content/abstract/68/2/165.
Shih LC, Tarsy D. Deep brain stimulation for the treatment of atypical parkinsonism. Mov Disord. 2007;22:2149-2155.
Weaver FM, Follett K, Stern M, et al, CSP 468 Study Group. Bilateral deep brain stimulation vs best medical therapy for patients with advanced Parkinson disease: a randomized controlled trial. JAMA. 2009;301:63-73.
Derost PP, Ouchchane L, Morand D, et al. Is DBS-STN appropriate to treat severe Parkinson disease in an elderly population? Neurology. 2007;68:1345-1355.