Long-term effects of bilateral subthalamic nucleus stimulation in advanced Parkinson disease: a four year follow-up study.

In this study we aimed to investigate the effects of bilateral STN HFS in patients with advanced Parkinson disease (PD) at long-term, with a minimum follow-up of 4 years. Twenty patients (15 men, five women) were included, with a mean age of 60.9+/-8.1 years. Surgery was performed under local anesthesia. The target was defined on computerized tomography (CT). At 3 months, significant improvements were found on the total Unified Parkinson disease rating scale (UPDRS) III (motor) score, in the medication. off (from 42.3+/-9.3 to 19.5+/-6.4), as well as the medication on (from 18.6+/-12.1 to 10.1+/-5.9) phase. The UPDRS IVa (dyskinesias) and IVb (motor fluctuations) scores decreased significantly. At long-term follow-up, there were still significant improvements on the total UPDRS III motor score (from 42.3+/-9.3 to 24.2+/-13.2), as well as in all motor subscores, in the off phase, during stimulation. In the on phase, the only significant improvement was seen for rigidity. Complications included hypomania to mania in four patients. Our results indicate that HFS STN results in long-lasting improvement of the motor symptoms, ADL activities and functional performance in patients suffering from advanced PD. The stimulation induced behavioural changes need special consideration.