International Congress of Parkinsons Disease and Movement Disorders edition:13 location:Paris, France date:June 7-11 2009
Objective: (1) To investigate whether freezing of gait (FOG) is affected by bilateral subthalamic nucleus (STN) stimulation in comparison to medicated patients with a similar disease profile.
Background: Previous study suggests that STN-stimulation improves levodopa-responsive FOG in most patients, but induces FOG in some. However, this was never compared with a control group.
Methods: We consecutively recruited 13 patients who underwent STN stimulation and 15 controls, eligible for surgery but on regular drug treatment. Inclusion criteria were: disease duration >5 years and disturbing motor fluctuations, dyskinesias or medication resistant tremor. Exclusion criteria were: cognitive decline, Hoehn & Yahr IV-V in on and persistent psychosis or depression. A clinical test battery was performed before surgery (T1) and 6 months after (T2). Primary outcome was the new Freezing of Gait Questionnaire (NFOGQ). Secondary outcome was the UPDRS III. Statistical analysis included non-parametric tests.
Results: At T1 no significant differences were found between the control and STN group for age, sex, disease duration, UPDRS III and Hoehn & Yahr scores. Five out of 15 controls and 4/13 STN patients experienced on-FOG (P=0.88) at T1 and most patients in both groups (14/15 and 11/13) had off-FOG (P=0.46). At T2 11 controls and 10 STN patients were retested. Overall no group differences were observed in change scores over the study period. Within-group differences revealed that the STN group improved significantly at T2 on the NFOGQ score with 18% (P=0.01). In 4/10 patients off-FOG and in 5/10 on-FOG disappeared completely. However, 2/10 developed on-FOG and 1/10 off-FOG over the study period. Controls remained stable on the NFOGQ-score. The number of controls with off-FOG remained also constant over 6 months and in 1/11 on-FOG disappeared. Conversely, 3/11 controls developed on-FOG. UPDRS III scores improved significantly in the STN group (p=0.009) whereas controls tended to deteriorate with time (p=0.8).
Conclusions: It was confirmed that after STN stimulation subjects showed overall improvement of FOG, but also developed FOG as a new symptom in 2 cases. Although this pattern was not significantly different from controls, off-FOG remained stable in non-operated patients and on-FOG increased.