According to this study:
• Deep brain stimulation improved motor function and quality of life but increased the risk of serious adverse events.
Weaver and colleagues enrolled 255 patients, 25% of whom were age 70 or older, with advanced Parkinson's disease that was responsive to levodopa. Deep brain stimulation patients had leads implanted in either the subthalamic nucleus (n = 60) or globus pallidus (n = 61). The care of the control group, patients receiving best medical therapy (n = 134), was managed by movement disorder neurologists.
Follow-up at six months showed an average gain of 4.6 hours per day of good motor function and symptom control, known as "on" time, in patients receiving deep brain stimulation, compared with no hours gained in the best-medical-therapy group. Improvement in motor function was significantly greater in the deep-brain-stimulation group (71%) than in the best-medical-therapy group (32%). Quality-of-life scores also improved significantly in the deep-brain-stimulation group while showing little change in the control group. However, deep brain stimulation produced small decreases in neurocognitive function and carried a risk of adverse events, such as pain, headache, and speech disorders, that was nearly four times higher than that with the best medical therapy. The risks and benefits of deep brain stimulation must be considered when choosing a treatment for advanced Parkinson's disease.—JC