Acta neurochirurgica. Supplement
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Acta Neurochir. Suppl. · Jan 2007
ReviewAn introduction to operative neuromodulation and functional neuroprosthetics, the new frontiers of clinical neuroscience and biotechnology.
Operative neuromodulation is the field of altering electrically or chemically the signal transmission in the nervous system by implanted devices in order to excite, inhibit or tune the activities of neurons or neural networks and produce therapeutic effects. It is a rapidly evolving biomedical and high-technology field on the cutting-edge of developments across a wide range of scientific disciplines. The authors review relevant literature on the neuromodulation procedures that are performed in the spinal cord or peripheral nerves in order to treat a considerable number of conditions such as (a) chronic pain (craniofacial, somatic, pelvic, limb, or due to failed back surgery), (b) spasticity (due to spinal trauma, multiple sclerosis, upper motor neuron disease, dystonia, cerebral palsy, cerebrovascular disease or head trauma), (c) respiratory disorders, (d) cardiovascular ischemia, (e) neuropathic bladder, and (f) bowel dysfunction of neural cause. ⋯ The authors highlight promising lines of research such as endoneural prostheses for peripheral nerve stimulation, closed-loop systems for responsive neurostimulation or implanted microwires for microstimulation of the spinal cord to enable movements of paralyzed limbs. The above growing scientific fields, in combination with biological regenerative methods, are certainly going to enhance the practice of neuromodulation. The range of neuromodulatory procedures in the spine and peripheral nerves and the dynamics of the biomedical and technological domains which are reviewed in this article indicate that new breakthroughs are likely to improve substantially the quality of life of patients who are severely disabled by neurological disorders.
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Functional neuroimaging has demonstrated that a relationship exists between the intensity of deafferentation pain and the degree of deafferentation-related reorganization of the primary somatosensory cortex. It has also revealed that this cortical reorganization can be reversed after the attenuation of pain. Deafferentation pain is also associated with hyperactivity of the somatosensory thalamus and cortex. ⋯ The first studies demonstrated a statistically significant pain suppression in all patients and a clinically significant pain suppression in 80% of them. This clinical experience suggests that somatosensory cortex stimulation may become a neurophysiology-based new approach for treating deafferentation pain in selected patients. In this chapter, we review the relevant recent reports and describe our studies in this field.
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Acta Neurochir. Suppl. · Jan 2007
ReviewSpinal cord stimulation in the treatment of chronic critical limb ischemia.
This paper reviews the clinical experience and proposed working mechanisms of spinal cord stimulation (SCS) in the treatment of chronic critical limb ischemia (CCLI). SCS appears to provide a significant long-term relief of ischemic pain and to improve healing of small ulcers, most likely due to effects on the nutritional skin blood flow. Despite these observations, randomized trials were not able to show limb salvage. Assessment of the microcirculatory skin blood flow, by means of transcutaneous oxygen pressure measurements and videocapillaromicroscopy, is necessary to evaluate the remaining microcirculatory reserve capacity likely to be exploited by SCS and to help identify patients that will benefit most from this treatment and in whom stimulation could lead to limb salvage.
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Vagus nerve stimulation (VNS) is an established treatment for selected patients with medically refractory seizures. Recent studies suggest that VNS could be potentially useful in the treatment of resistant depressive disorder. ⋯ VNS is currently investigated in clinical studies, as a potential treatment for essential tremor, cognitive deficits in Alzheimer's disease, anxiety disorders, and bulimia. Finally, other studies explore the potential use of VNS in the treatment of resistant obesity, addictions, sleep disorders, narcolepsy, coma and memory and learning deficits.
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For more than 20 years intrathecal opioid application with implantable pumps is an option for selected patients with malignant as well as non-malignant pain. In general, most types of pain should be treatable by opioid medication. However, the associated systemic side-effects such as nausea, vomiting, constipation or the risk of suppression of the central nervous system hinder the application of oral or intravenous opioid therapy as a sole, widely applicable treatment. ⋯ Intrathecal drug application is cost effective and can significantly improve the quality of life in selected patients. An intensive training in this method and awareness of its specific complications is necessary for everyone to participate in the consulting and implanting team. Pumps for chronic intrathecal opioid application should only be implanted in specialized centers.