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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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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Neglected tropical diseases are a group of mostly infectious diseases that thrive among poor populations in tropical countries. A significant proportion of the conditions affecting the neurological system in such countries can be attributed to neglected tropical diseases of helminth, protozoan, bacterial, or viral origin. ⋯ In resource-poor settings it is likely that many infections will not be treated and will therefore progress into their advanced and severe stages, thus being increasingly associated with irreversible morbidity; this is also the case for neurological morbidity, which often entails permanent disability. Public health should aim at reducing the burden of tropical neurological diseases through interventions addressing the infection, the associated morbidity, and the disability deriving from it.
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The few reported controlled studies show that bilateral stimulation of the globus pallidus interna (GPi) is a safe and effective long-term treatment for hyperkinetic disorders. However, the recently published data on deep brain stimulation (DBS) applied to different targets or patients (especially those with secondary dystonia) are mainly uncontrolled case reports, precluding a clear determination of its efficacy, and providing little guidance as to the choice of a "good" target in a "good" patient. This chapter reviews the literature on DBS in primary dystonia, paying particular attention to the risk:benefit ratio in focal and segmental dystonias (cervical dystonia, cranial dystonia) and to the predictive factors for a good outcome. ⋯ This chapter provides a comprehensive analysis of the use of the treatment in various types of secondary dystonia, with little to moderate benefit in most cases, based on single cases or small series. Beyond the reduction in the severity of dystonia, the global motor and functional outcome is difficult to determine owing to the paucity of adequate evaluation tools. Because of the large interpatient variability, different targets may be effective depending on the symptoms in each individual.