A 2-year trial involving 251 patients with Parkinson's disease and early motor complications (mean age, 52 years; mean duration of disease, 7.5 years) has found that those given deep brain stimulation surgery significantly improved their quality of life, motor disability, activities of daily living, levodopa-induced motor complications, and time with good mobility and no dyskinesia. Those given normal medical therapy, on the other hand, declined or at best got no worse. Serious adverse events related to surgical implantation or the neurostimulation device occurred in 18% of patients.
“The study has confirmed the best medical practice for a person with Parkinson’s disease is to perform DBS surgery around 4 to 7 years into the condition, as opposed to waiting until the medications stop working.”
 Neurostimulation for Parkinson's Disease with Early Motor Complications. New England Journal of Medicine [Internet]. 2013 ;368(7):610 - 622. Available from: http://www.nejm.org/doi/full/10.1056/NEJMoa1205158