Abstract

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has been gaining importance in the treatment of advanced Parkinson's disease. This study was undertaken to evaluate the beneficial effects of bilateral STN stimulation on patient's clinical symptoms and quality of life related to the potential risks and side effects of the treatment.

A consecutive series of 42 patients operated on for Parkinson's disease with STN DBS in Oulu University Hospital were included. A subgroup of these patients was evaluated using the Unified Parkinson's Disease Rating Scale (UPDRS), neuropsychological tests, and Health Related Quality of Life (HRQoL) instruments i.e. the Parkinson's Disease Questionnaire (PDQ-39) and the Finnish version of the Nottingham Health Profile (NHP). The costs of the treatment were calculated from the perspective of the health care provider. The possible effects of bilateral STN-operation on cardiovascular autonomic function were analyzed by measuring various time- and frequency domain indexes as well as non-linear indexes of heart rate variability (HRV) from 24-hour EKG recording before and 12 months after the operation.

This study showed that STN DBS significantly improves the clinical symptoms and HRQoL of parkinsonian patients. The dyskinesia and clinical fluctuation scores were reduced very significantly in the UPDRS IV subscale. The clinical fluctuations were reduced by 53 %. After DBS best motor response (UPDRS III) scores also improved significantly. The HRQoL measured with both instruments improved significantly. Improvement was seen in the PDQ-39 summary index and the subscales of activities of daily living, emotional well-being, stigma and bodily discomfort. Only communication became worse during the follow-up. There was a statistically significant improvement in the score of the subscales of NHP measuring problems with energy, sleep, emotional reactions and social isolation. One patient died from pulmonary embolism and another contracted a late postoperative intracerebral hemorrhage leading to a permanent deterioration of her neurological condition to the bedridden stage. Other complications were much milder.

Clinical improvement and improvement in HRQoL were positively correlated. STN DBS does not influence tonic autonomic cardiovascular regulation. The incremental costs of performing bilateral STN DBS in Finland compared to preoperative medical treatment amounted to an average of 25 591 EUR per patient during the first postoperative year.

The majority of parkinsonian patients experienced significant and long lasting relief in their motor symptoms and an improvement in HRQoL following STN stimulation.