Neuromodulation : journal of the International Neuromodulation Society
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Objectives. The purpose of the present study was to show that the design of a neuroprosthesis for unsupported (arm-free) standing is feasible. We review findings suggesting that a closed-loop controlled functional electrical stimulation (FES) system should be able to facilitate arm-free quiet standing in individuals with spinal cord injury (SCI). Particularly, this manuscript identifies: 1) a control strategy that accurately mimics the strategy healthy individuals apply to regulate the ankle joint position during quiet standing and 2) the degrees of freedom (DOF) of the redundant, closed-chain dynamic system of bipedal stance that have to be regulated to facilitate stable standing. ⋯ Finally, perturbation simulations confirmed that the kinematics of this system are similar to those of healthy individuals during perturbed standing. Conclusions. The presented results suggest that stable standing can be achieved in individuals with SCI by controlling only six DOF in the lower limbs using FES, and that a PD controller actuating these DOF can stabilize the system despite a long sensory-motor time delay. Our finding that not all DOF in the lower limbs need to be regulated is particularly relevant for individuals with complete SCI, because some of their muscles may be denervated or difficult to access.
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Objective. This study aims to assess peripheral nerve field stimulation as a treatment option for chronic pain and test for indicators of outcome. Materials and Methods. We reviewed all patients permanently implanted with peripheral nerve field stimulators over the past 24 months. A questionnaire was used to assess outcomes. ⋯ Most patients reported decreases in analgesic use after treatment. Pain relief was significantly and highly correlated with reduced analgesic intake and patient satisfaction. Conclusion. Peripheral nerve field stimulation is a safe, reversible, and effective treatment option for patients with chronic pain, particularly those under 60 years.
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Objectives. The pain associated with herpes zoster can be classified as acute phase, persistent phase, or chronic phase, but if it is prolonged, it becomes resistant to treatment. It is clinically important to prevent transition to postherpetic neuralgia after the onset of herpes zoster, and the outcome depends on whether continuous and potent pain management can be achieved between the acute and persistent phases. We evaluated the effect of pain management leading to quick termination of pain using temporary spinal cord stimulation (SCS) which does not require implantation of a device. ⋯ Less epidural analgesia was required and the adverse reactions of lowered blood pressure in three cases and urinary retention in seven cases disappeared soon. The self-rated satisfaction was higher with SCS than with CEB in all 14 cases, because it is highly controllable and has minimal activities of daily living-lowering effects. Conclusion. Temporary SCS, which does not require implantation of a device, may have a potent analgesic effect on severe pain in patients in the persistent phase after herpes zoster, and prevent transition to postherpetic neuralgia.
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Among the surgical treatment options for patients with medically refractory dystonia chronic deep brain stimulation (DBS) of different targets in the basal ganglia circuitry has become one of the most important tools. The globus pallidus internus nowadays is the target of choice, while there is only limited experience with other targets. At this time, patients with primary (genetic or sporadic) generalized and segmental dystonia, and patients with (complex) cervical dystonia are thought to be the best candidates for pallidal DBS. ⋯ We also provide an overview on DBS surgery in less common dystonic syndromes, such as craniofacial dystonia, status dystonicus, task-specific dystonia, paroxysmal dystonia, camptocormia, and secondary dystonias, including choreoathetosis, hemidystonia, tardive dystonia, and pantothenate kinase-associated neurodegeneration. Furthermore, we discuss the implications of intra-operative microelectrode recordings and pallidal field potentials for the pathophysiology of dystonia and the particular possible mechanisms of DBS in dystonia. Finally, future perspectives are outlined.