Neuromodulation : journal of the International Neuromodulation Society
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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.
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Spinal cord stimulator lead migration is a common problem. Anchor design may be a factor in its prevention. We have undertaken a cadaveric and in vitro comparative investigation of the force required to cause lead migration with a variety of anchor types. ⋯ The titanium anchor prevents simulated lead movement at greater forces that the silastic anchors with a variety of leads. For silastic anchors, movement occurred at median force below that simulated with spinal movement; for the titanium anchor, movement occurred at a median force above that simulated with spinal movement. Further in vivo investigations are warranted to assess the potential of titanium anchoring to significantly reduce spinal cord stimulator lead migration.
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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.