Efficiency and safety of bilateral contemporaneous pallidal stimulation (deep brain stimulation) in levodopa-responsive patients with Parkinson's disease with severe motor fluctuations: a 2-year follow-up review

Object. The aim of this study was to evaluate the long-term safety and effi cacy of bilateral contemporaneous deep brain stimulation (DBS) in patients who have levodopa-responsive parkinsonism with untreatable motor fluctuatio ns. Bilateral pallidotomy carries a high risk of corticobulbar and cognitiv e dysfunction. Deep brain stimulation offers new alternatives with major ad vantages such as reversibility of effects, minimal permanent lesions, and a daptability to individual needs, changes in medication, side effects, and e volution of the disease. Methods. Patients in whom levodopa-responsive parkinsonism with untreatable severe motor fluctuations has been clinically diagnosed underwent bilatera l pallidal magnetic resonance image-guided electrode implantation while rec eiving a local anesthetic. Pre- and postoperative evaluations at 3-month in tervals included Unified Parkinson's Disease Rating Scale (UPDRS) scoring, Hoehn and Yahr staging, 24-hour self-assessments, and neuropsychological ex aminations. Six patients with a mean age of 55 years (mean 42-67 years), a mean duratio n of disease of 15.5 years (range 12-21 years), a mean "on/off" Hoehn and Y ahr stage score of 3/4.2 (range 3-5), and a mean "off" time of 40% (range 2 0-50%) underwent bilateral contemporaneous pallidal DBS, with a minimum fol low-up period lasting 24 months (range 24-30 months). The mean dose of levo dopa in these patients could not be changed significantly after the procedu re and pergolide was added after 12 months in five patients because of recu rring fluctuations despite adjustments in stimulation parameters. All but t wo patients had no fluctuations until 9 months. Two of the patients reporte d barely perceptible fluctuations at 12 months and two at 15 months; howeve r, two patients remain without fluctuations at 2 years. The mean improvemen ts in the UPDRS motor score in the off time and the activities of daily liv ing (ADL) score were more than 50%; the mean off time decreased from 40 to 10%, and the mean dyskinesia and complication of treatment scores were redu ced to one-third until pergolide was introduced at 12 months. No significan t improvement in "on" scores was observed. A slight worsening after 1 year was observed and three patients developed levodopa- and stimulation-resista nt gait ignition failure and minimal fluctuations at 1 year. Side effects, which were controlled by modulation of stimulation, included dysarthria, dy stonia, and confusion. Conclusions. Bilateral pallidal DBS is safe and efficient in patients who h ave levodopa-responsive parkinsonism with severe fluctuations. Major improv ements in motor score, ADL score, and off time persisted beyond 2 years aft er the operation, but signs of decreased efficacy started to be seen after 12 months.