Field H1 of Forel vs Subthalamic Nucleus Electrical Stimulation in Parkinson's Disease: Long-term Effects on Motor Symptoms and Quality of Life.

Background: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) relieves motor symptoms, including levodopa-responsive gait disorders in Parkinson's disease (PD). Traditionally, STN-DBS is not indicated to treat severe, clinically resistant axial symptoms. In this scenario, field H1 of Forel (FF) stimulation (FF-DBS) is likely a feasible option, given it improves motor symptoms, including freezing of gait (FOG), as shown by a short-term study. However, no data are available about the long-term effects of this therapy. Finally, no study has compared the long-term effects of FF and STN-DBS.

Objective: We report the long-term outcome (>five years) of bilateral FF-DBS in patients with PD. We also compare the effects of FF-DBS and STN-DBS on motor symptoms, cognition, and quality of life.

Materials and methods: We studied 22 patients (ten with FF-DBS and 12 with STN-DBS). Motor symptoms, cognition, quality of life, and gait symptoms were assessed using the motor part of the Movement Disorders Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS III), the Mattis Dementia Rating Scale, the 39-item PD quality of life (PDQ-39), and the FOG questionnaire (FOG score) respectively. The levodopa equivalent daily dose was recorded. Comparisons of the FF and STN-DBS results were conducted.

Result: The mean follow-up was 6.18 years (95% CI: 5.57-6.78). Compared with the preoperative period, patients with FF had an average reduction of 32.2% in the MDS-UPDRS III scores (p < 0.01), a decrease of 35.3% in the FOG scores (p < 0.01), and an improvement of 25.9% in the PDQ-39 (p < 0.01). There was a 7.5% decrease in cognition (p < 0.01). Levodopa equivalent dose (LED) was reduced by 26.3% (p < 0.01). The STN group had an average reduction of 39.4% in the MDS-UPDRS III scores (p < 0.01), a decrease of 23.7% in the FOG scores (p < 0.01), and an improvement of 33.2% in the PDQ-39 scores (p < 0.01). Cognition decreased by 1.6% (p < 0.01) and LED by 15.06% (p = 0.02). Patients with FF-DBS were older than those with STN-DBS at the time of surgery: 61.2 years and 55.7 years, respectively (p = 0.02), and had longer duration of disease (p = 0.02). Patients with FF-DBS had a greater reduction in FOG (p = 0.02) than did the STN group and presented with a greater decrease in cognition (p < 0.01) after five years. STN-DBS had a greater effect on quality of life.

Conclusions: Both FF-DBS and STN-DBS relieved motor symptoms and improved quality of life over a long-term period. Patients with FF-DBS had a higher reduction in both FOG and in LED than did those with STN-DBS. These data support our hypothesis that FF-DBS is a safe and efficient option for treating motor symptoms in PD, including FOG in advanced stages.