By Mashawnda Dowell
WASHINGTON, DC -- May 4, 2007 -- High-frequency stimulation (HFS) of the subthalamic nucleus (STN) is a safe, effective, and stable treatment for patients with advanced Parkinson's disease, according to a retrospective evaluation of this technique.
Lead author Alim L. Benabid, MD, PhD, director, department of neurosurgery, Centre Hospitalier Universitaire A. Michallon, Grenoble, France, discussed the study's results here at the American Association of Neurological Surgeons (AANS) annual meeting.
Currently, STN-HFS is the treatment of choice for treating patients with advanced Parkinson's disease. Dr. Benabid and colleagues studied the evolution of the cardinal features of this technique in a 14-year series that included 304 patients.
Enrolled patients underwent surgery in the STN since 1993 (296 bilaterally, 600 electrodes). The researchers retrospectively analyzed the duration of benefit, active contact coordinates, complications, and long-term changes in the nature of the disease.
Improvement in major symptoms was an average of 65% for the major Parkinson's symptoms as evaluated using the Unified Parkinson's Disease Rating Scale, Hoehn and Yahr Staging of Parkinson's Disease, and quality-of-life scales. Improvement in speech was an average of 35%.
Drug dosages, and subsequently the levodopa-induced dyskinesias, were decreased by an average of 65%. This was linearly correlated to the preoperative levodopa-induced improvement and was strictly dependent on the accurate placement of the leads, according to the researchers.
The benefit of STN-HFS persisted in levodopa-sensitive symptoms such as tremor, akinesia, and rigidity, but not for midline symptoms such as balance and gait. Patients' baseline condition (off medication, off stimulation) worsened in 25% of patients, was stable in 36% of patients, and improved in 38%. Improvements continued over 5 years in 19% of patients.
The researchers determined that mild and transient complications were due to pretargeting (5.7%), implantation (30%), stimulation (19.6%), and hardware failure (16.7%). Complications decreased by a ratio of 2.3 with the learning curve of operators who performed the procedure.
There were psychic disorders in 8.3%, one procedure-related death, and one suicide.
The researchers concluded that STN-HFS is safe, effective, and stable over time. "Careful surgical practice and patient selection improve the outcome," the noted.
[Presentation title: Retrospective Study of a 13 Year Series of 304 Parkinson's Disease Patients Treated by STN High Frequency Stimulation. Poster 1526]
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