Long Term Response to Levodopa in Parkinson’s Disease

Background Levodopa is the most efficacious medication in controlling the motor symptoms of Parkinson's disease (PD). There continues to be a controversy as to whether levodopa remains effective after years of therapy. Objective To assess the long-term effectiveness of levodopa in PD patients. Methods The response to levodopa in PD patients undergoing a levodopa challenge for deep brain stimulation (DBS) surgery evaluation from June 1997 through March 2017 were evaluated. The patients were broken into four groups based on disease duration (Group I: 0- 5 years, Group II: 6- 10 years, Group III: 11- 15 years, and Group IV:≥16 years). Levodopa response was calculated based on the changes in Unified Parkinson's Disease Rating Scale (UPDRS) motor and activities of daily living (ADL) scores in the medication ON and OFF states. Results A total of 361 PD patients were included. The mean age in Group I was 59.4 years with a mean disease duration of 3.9 years (n = 29), Group II was 61 years with a mean disease duration of 8.1 years (n = 131), Group III was 64 years with a mean disease duration of 12.8 years (n = 143), and IV was 66.5 years with a mean disease duration of 18.5 years (n = 58). There was a significant improvement in UPDRS motor and ADL scores after the levodopa challenge for all groups. Conclusions In a subgroup of PD patients who were evaluated for DBS surgery, there was a marked improvement in UPDRS motor and ADL scores which did not decrease with disease progression.