Neuromodulation : journal of the International Neuromodulation Society
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Ever since its initial development in the late 1960s, spinal cord stimulation (SCS) has been used to treat a number of painful conditions. European practice, in contrast to that in North America, has used peripheral arterial disease (PAD) as a primary indication for SCS. First employed in patients with PAD in 1976, SCS was shown by Cook et al. to heal chronic leg ulcers. ⋯ Recent randomized prospective studies have questioned some of the conclusions from these preceding retrospective data. In addition to the questions related to outcomes, theories regarding exact mechanisms by which SCS improves circulatory parameters remain unclear. A thorough Medline literature review on the subject of SCS in peripheral vascular disease was thus undertaken to attempt to clarify questions regarding which patients are best suited for SCS therapy, pinpoint possible methodologic flaws in previous studies, and to review the background, outcomes, mechanisms of action, complications, and alternatives for SCS in patients with PAD.
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We present data collected from a multicenter study using a new neurostimulation system. This new system uses a current-shifting programming technique for spinal cord stimulation. The system maintains a continuous, suprathreshold stimulation field while adjusting the distribution of anodic and cathodic current among contacts along a multi-contact array. ⋯ This multicenter study evaluated the performance of the CEFA technique. The results of the study showed that paresthesia coverage could be shifted in real-time to different regions on the patient's body in a comfortable fashion, with the patient always feeling paresthesia during the adjustment process. The results of the study also show that the process was time-efficient: intraoperatively, the median time to assess 71 combinations on a single 8-contact lead across 18 patients was 4.1 (3.6-5.0) minutes.
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The objective of this study was to develop and test the feasibility of a model that employs electromyographic (EMG) signals to predict the occurrence of gait events in the child with cerebral palsy (CP). This model could be the basis of a future functional electrical stimulation (FES) control system to assist gait. Two children were implanted with bifilar intramuscular electrodes into the quadriceps muscle bilaterally. ⋯ For nine of the 10 gait events evaluated, the model predicted gait events to within 82 ms on average, as referenced to the VICON motion analysis system. For eight of the 10 events, prediction errors were 0.3% or less. Results indicate that EMG from the proximal musculature could be used to predict the occurrence of gait events in these two children with CP.
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This study investigated the activation dynamics of electrical stimulation-evoked muscle contractions performed by individuals with spinal cord injury (SCI). The purpose was to determine whether electrical stimulation (ES) firing patterns during cycling exercise should be altered in response to fatigue-induced changes in the time taken for force to rise and fall with ES. Seven individuals with SCI performed isometric contractions and pedaled a motorized cycle ergometer with stimulation applied to the quadriceps muscles. ⋯ Cycling power output fell approximately 50% during the five minutes of exercise, however, there was no change in the time taken for torque to rise or fall. The magnitude of ES-evoked muscle torques decline substantially with fatigue, however, the overall pattern of torque production remained relatively unchanged. These results suggest there is no need to alter stimulation firing patterns to accommodate fatigue during ES-evoked exercise.
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Phantom limb pain (PLP) is a type of neuropathic pain syndrome that has evoked much interest in scientific and clinical fields. The condition is often intractable and severely debilitating. Though there are anecdotal reports in the literature of successful management of individual cases with brain and spinal cord stimulation, it has not been possible to develop a system of management that is consistently successful, mainly due to the paucity of basic neurophysiological data about PLP and its pathways in the central nervous system (CNS). ⋯ We describe two cases of PLP that have been satisfactorily treated with CNS stimulation (motor cortex and then periventricular gray in one and spinal cord in the other) and have been subjected to single photon emission computed tomography (SPECT) studies when in pain and then during stimulation with recorded pain relief. We found that regardless of the site of stimulation in the CNS, pain relief is associated with blood flow changes in similar areas of the brain, mainly the parietal and cingulate cortex and also in the thalamic nuclei and the central gray matter. Further studies of this kind should reveal more about the complex mechanisms of PLP and other forms of neuropathic pain.