Okun, M. S. et al. Subthalamic deep brain stimulation with a constant-current device in Parkinson's disease: an open-label randomised controlled trial. Lancet Neurol. 11, 140-149

Department of Neurology, Center for Movement Disorders and Neurorestoration, University of Florida College of Medicine, Gainesville, FL 32607, USA. .edu
The Lancet Neurology (Impact Factor: 21.9). 02/2012; 11(2):140-9. DOI: 10.1016/S1474-4422(11)70308-8
Source: PubMed


The effects of constant-current deep brain stimulation (DBS) have not been studied in controlled trials in patients with Parkinson's disease. We aimed to assess the safety and efficacy of bilateral constant-current DBS of the subthalamic nucleus.
This prospective, randomised, multicentre controlled trial was done between Sept 26, 2005, and Aug 13, 2010, at 15 clinical sites specialising in movement disorders in the USA. Patients were eligible if they were aged 18-80 years, had Parkinson's disease for 5 years or more, and had either 6 h or more daily off time reported in a patient diary of moderate to severe dyskinesia during waking hours. The patients received bilateral implantation in the subthalamic nucleus of a constant-current DBS device. After implantation, computer-generated randomisation was done with a block size of four, and patients were randomly assigned to the stimulation or control group (stimulation:control ratio 3:1). The control group received implantation without activation for 3 months. No blinding occurred during this study, and both patients and investigators were aware of the treatment group. The primary outcome variable was the change in on time without bothersome dyskinesia (ie, good quality on time) at 3 months as recorded in patients' diaries. Patients were followed up for 1 year. This trial is registered with, number NCT00552474.
Of 168 patients assessed for eligibility, 136 had implantation of the constant-current device and were randomly assigned to receive immediate (101 patients) or delayed (35 patients) stimulation. Both study groups reported a mean increase of good quality on time after 3 months, and the increase was greater in the stimulation group (4·27 h vs 1·77 h, difference 2·51 [95% CI 0·87-4·16]; p=0·003). Unified Parkinson's disease rating scale motor scores in the off-medication, on-stimulation condition improved by 39% from baseline (24·8 vs 40·8). Some serious adverse events occurred after DBS implantation, including infections in five (4%) of 136 patients and intracranial haemorrhage in four (3%) patients. Stimulation of the subthalamic nucleus was associated with dysarthria, fatigue, paraesthesias, and oedema, whereas gait problems, disequilibrium, dyskinesia, and falls were reported in both groups.
Constant-current DBS of the subthalamic nucleus produced significant improvements in good quality on time when compared with a control group without stimulation. Future trials should compare the effects of constant-current DBS with those of voltage-controlled stimulation.
St Jude Medical Neuromodulation Division.

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    • "Stimulation devices of the first generation delivered electrical stimulation in a voltage-controlled mode whereas following devices predominantly use the constant-current mode or can be switched into this mode. In comparison to constant-current devices, where the stimulation field is kept stable in size, the stimulation field produced by constant-voltage devices is vulnerable to changing tissue impedances (Lempka et al., 2010; Okun et al., 2012). The most frequent programming parameters are monopolar stimulation, impulse duration 60–90 µs and frequency 130 Hz (Volkmann et al., 2006). "
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    ABSTRACT: Deep brain stimulation has become a well-established symptomatic treatment for Parkinson's disease during the last 25 years. Besides improving motor symptoms and long-term motor complications, positive effects on patients' mobility, activities of daily living, emotional well-being and health-related quality of life have been recognized. Apart from that, numerous clinical trials analyzed effects on non-motor symptoms and side effects of deep brain stimulation. Several technical issues and stimulation paradigms have been and are still being developed to optimize the therapeutic effects, minimize the side effects and facilitate handling. This review summarizes current therapeutic issues, i.e., patient and target selection, surgical procedure and programming paradigms. In addition it focuses on neuropsychological effects and side effects of deep brain stimulation.
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    • "It should be noted, however, that clinically available anti-cholinergics (e.g., trihexyphenidyl, benztropine, etc.) mainly act as competitive antagonists at mAChRs. A stepwise executive dysfunction has been described in cognitively intact PD patients (Taylor et al., 1986) who suffer damage to the frontal lobes and/or fibers connecting the frontal lobes with the head of the caudate during electrode implantation for deep brain stimulation (Okun et al., 2012). The role of [ 123 I]5IA- SPECT as a screening tool for identifying patients at risk for (surgery-related) cognitive decline should be further investigated. "
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