Handbook of clinical neurology
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A variety of noninvasive brain stimulation techniques have been used to study neuronal plasticity. Mostly, noninvasive techniques have been employed, and the bulk of studies have focused on the motor system, because its physiology is more readily accessible and physiological properties can be studied with greater detail than in other systems. ⋯ Several of the phenomena induced by noninvasive brain stimulation have been mapped on to cellular physiological mechanisms such as synaptic long-term potentiation or long-term depression. Although some parallelisms are intriguing, this approach has also its limitations, and more direct verification of physiological phenomena by animal studies is needed.
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One of the most exciting areas in epilepsy has been the explosion in our understanding of the genetics of the epilepsies over the last decade. Built on a long history of careful clinical genetic studies of the epilepsies, the relatively recent discovery of epilepsy genes has enabled insights into pathways causing seizure disorders. A variety of mutational mechanisms can cause epilepsy resulting from different, and sometimes surprising, molecular processes such as copy number variation within the genome. ⋯ The architecture of the common genetic epilepsies following complex inheritance, where multiple genes are involved, is also beginning to be unraveled. The clinical approach to understanding the genetics of the epilepsies has matured and requires a detailed family history of seizures together with delineation of the child's epilepsy syndrome. Recognition of specific genetic epilepsy syndromes enables optimal treatment and prognostic and genetic counseling.
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Magnetic resonance imaging (MRI) has become the standard of care for the evaluation of different neurological disorders of the brain and spinal cord due to its multiplanar capabilities and excellent soft tissue resolution. With the large and increasing population of patients with implanted deep brain stimulation (DBS) devices, a significant proportion of these patients with chronic neurological diseases require evaluation of their primary neurological disease processes by MRI. ⋯ These include the potential for induction of electrical currents or heating in DBS devices, which can result in neurological tissue injury, magnetic field-induced device migration, or disruption of the operational aspects of the devices. In this chapter, we review the basic physics of potential interactions of the MRI environment with implanted DBS devices, summarize results from phantom studies and clinical series, and discuss present recommendations for safe MRI in patients with implanted DBS devices.
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Fabry disease results from deficient activity of the enzyme α-galactosidase A and progressive lysosomal deposition of globotriaosylceramide (GL-3) in cells throughout the body. The main neurological presentations of Fabry disease patients are painful neuropathy, hypohidrosis, and stroke. Fabry neuropathy is characterized as a length-dependent peripheral neuropathy affecting mainly the small myelinated (Aδ) fibers and unmyelinated (C) fibers. ⋯ Early initiation of ERT before irreversible organ failure is extremely important, and alternative therapeutic approaches are currently being explored. Heterozygotes suffer from peripheral neuropathy at a higher rate than previously shown, significant multisystemic disease, and severely decreased quality of life. As well as being carriers, heterozygotes also display symptoms of Fabry disease, and should be carefully monitored and given adequate therapy.
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Peripheral neuropathies are the most common neurological manifestations occurring in HIV-infected individuals. Distal symmetrical sensory neuropathy is the most common form encountered today and is one of the few that are specific to HIV infection or its treatment. The wide variety of other neuropathies is akin to the neuropathies seen in the general population and should be managed accordingly. ⋯ One is left with cannabis, which cannot be recommended as routine therapy, recombinant human nerve growth factor, which is unavailable, and topical capsaicin with its side-effects. Much has been done to and learned from HIV infection in humans; HIV-infected individuals, treated with ART, are now dying mostly from cardiovascular disease and non-AIDS-related cancers. It hence behooves us to find new approaches to mitigate the residual neurological morbidity that still impacts the quality of life of that population.