Quality of life in advanced Parkinson's disease after bilateral subthalamic stimulation: 2 years follow-up study.

OBJECTIVE

The aims of this study were to assess the quality of life (QoL) using Parkinson's Disease Questionnaire PDQ-39 after bilateral subthalamic deep brain stimulation (STN DBS), and to identify correlations between changes in UPDRS score and separate PDQ-39 QoL dimensions and PDQ summary index (SI) score at long-term follow-up.

METHODS

We evaluated 16 patients with advanced PD after bilateral STN DBS. All 16 patients were assessed 1 year after surgery and 14 were studied 2 years after surgery. The patients were assessed using Unified Parkinson's Disease Rating Scale (UPDRS) in medication-on and medication-off conditions, both preoperatively and postoperatively. All UPDRS evaluations were performed postoperatively during stimulation-on condition. QoL levels were determined by applying PDQ-39 questionnaire.

RESULTS

The UPDRS scores after 1 and 2 years in medication-off and -on conditions when bilateral STN DBS was switched on showed a significant difference between baseline scores and follow-up scores (both in -off and -on conditions) in every UPDRS measurement except for mentation after 2 years. Most of P-values indicated that the differences were highly significant (P<0.01) based on Wilcoxon signed-rank test. All dimensions of PDQ-39 as well PDQ-39 SI score were highly significantly improved after 1 year. The same improvements were visible in 2 years follow-up with the exception of social support and communication. We found a positive correlation between ADL UPDRS, motor off UPDRS scores and PDQ-39 ADL and PDQ-39 SI scores. A further analysis of separate motor PD features revealed that tremor, bradykinesia and axial features were correlated with improvements mostly seen in PDQ-39 ADL and PDQ-39 SI scores. Moreover, in medication-on condition, we found a strong correlation between dyskinesia UPDRS score and PDQ-39 mobility, ADL, and PDQ-39 SI score. We observed a negative correlation between improved fluctuation UPDRS score and PDQ-39 mobility. We identified no correlation between the duration of the off period and levodopa dose and changes in PDQ-39.

CONCLUSION

STN DBS significantly improved important aspects of QoL as measured by PDQ-39. The improvements were maintained at 2 years follow-up except for social support and communication. We demonstrated a positive correlation between changes in the off condition of motor UPDRS scores and dyskinesia UPDRS scores in several PDQ-39 dimensions, whereas fluctuation UPDRS scores were negatively correlated with PDQ-39 mobility scores.