Bilateral high-frequency stimulation of the subthalamic nucleus in patients with multiple system atrophy--parkinsonism. Report of four cases.

The aim of this study was to investigate the effect of high-frequency stimulation (HFS) of the subthalamic nucleus (STN) in patients with a subtype of multiple system atrophy (MSA) in which levodopa-unresponsive MSA parkinsonism (MSA-P) is predominant. After a local anesthetic was administered, electrodes were stereotactically implanted bilaterally into the STN in four patients with MSA-P and predominantly akinetorigid symptoms. Unified Parkinson's Disease Rating Scale (UPDRS) scores were evaluated preoperatively, at 1 month, and at long-term follow up. At 1 month the median decrease in the UPDRS III motor score was 22 on the 56-point scale (decreases of 16, 13, 29, and 15 points compared with baseline for Cases 1, 2, 3, and 4, respectively). This was mainly due to an improvement in rigidity and akinesia. The median decrease in the UPDRS II score was 11 on the 52-point scale (respective decreases of 5, 7, 13, and 9 points). At 2 years (mean follow up 27 months) there was a median decrease in the UPDRS III score of 12 (respective decreases of 18, 13, 21, and 9 points), and in the UPDRS II score of 5 (with respective decreases of 2, 2, 17, and 2), both compared with the stimulation off state. At long-term follow up there was an increase in the individual Schwab and England scores of 10 to 15% in the stimulation on compared with the stimulation off condition. There was a beneficial effect of STN HFS in these four patients on both a short-term and a long-term basis. A larger prospective study is justified.