Rinshō shinkeigaku = Clinical neurology
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Over the last few years, various autoantibodies against cell surface or intracellular antigens were identified in association with several forms of encephalitis, i.e. autoimmune encephalitis. Immunoprecipitaion and sequence analysis of the target protein (proteomics) provided the identification of the antigens corresponding to autoantibodies in autoimmune encephalitis. Appropriate preparation of antigens (synthesized peptides, or recombinant proteins prepared in E.coli or cultured mammalian cells) and assay systems (immunoblot, ELISA, immunoprecipitation or cell-based assay) should be selected for detection of each autoantibodies. ⋯ Cerebellar ataxia is a common form of autoimmune encephalitis (cerebellits). The autoimmune cerebellar ataxia consists of paraneoplastic ataxia (anti-Yo etc.), anti-GAD-autoantibodies associated ataxia, gluten ataxia (anti-gliadin) and ataxic form of Hashimoto's encephalitis (anti-NAE). The early and accurate diagnosis of autoimmune encephalitis is important because most patients show responses to immunotherapy.
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Over the past decade, genome-wide association studies (GWASs) using common polymorphisms have been conducted to identify genetic risks associated with sporadic diseases. Although GWASs have successfully revealed numerous susceptibility genes for neurodegenerative diseases, the odds ratios associated with these risk alleles are generally low and account for only a small proportion of estimated familial clustering. ⋯ Using the clues provided by rare familial cases, we have recently identified strong genetic factors in Parkinson diseases and in multiple system atrophy based on the candidate gene approach. Focusing on the familial aggregation may be an efficient approach to identifying risk alleles of large effect sizes in apparently sporadic neurodegenerative diseases.
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Neuralgic amyotrophy (NA, also known as Parsonage-Turner syndrome) is a distinct peripheral nervous system (PNS) disorder, characterized by sudden attacks of severe neuropathic pain usually in the shoulder and/or arm. The neuralgia commonly disappears after a few days to weeks, and consequently patchy paresis with amyotrophy appears. The available evidence suggests that NA is essentially idiopathic immune-mediated neuritis of the brachial plexus, and also has a complex pathogenesis that includes an underlying predisposition, susceptibility to dysfunction of some PNS structure, and a trigger for the attacks, such as viral infection, vaccination, trauma, surgery, and strenuous exercise. ⋯ However, recent studies have indicated that the long-term prognosis of NA is less favorable than has been assumed. In 2009, a Cochrane review identified one open label, retrospective series, the results of which suggested that administration of corticosteroids in the acute phase of NA could shorten the duration of painful symptoms and also accelerate recovery in some patients. We recently have reported that intravenous immunoglobulin (IVIg) with methylpredonisolone pulse therapy is effective for motor impairment of NA.
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Anti-glycine receptor (anti-GlyR) antibodies were first reported in 2008 in a case of progressive encephalomyelitis with myoclonus and rigidity (PERM), which is a variant of stiff-person syndrome (SPS). After that, the antibodies have been studied extensively. At least 40 patients have been reported or presented until May 2013. ⋯ Twenty-one patients (75%) treated with immunotherapy or thymectomy improved, but two of six patients without immunotherapy died or developed cardiac arrest. The clinical features suggested that antibody-mediated inhibition of the GlyR on the brainstem nuclei or spinal inhibitory interneurons may cause continuous firing of α motor neurons and paroxysmal excessive response to a variety of afferent impulses, leading to increased stiffness, brainstem signs, trismus, myoclonus, painful spasms or hyperekplexia. Phenotype associated with the anti-GlyR antibodies may be broader than previously thought, but among those PERM is the most common phenotype.
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Isaacs' syndrome is an antibody-mediated potassium channel disorder. Clinical symptoms of Isaacs' syndrome are characterized by muscle cramp, slow relaxation following muscle contraction, and hyperhidrosis. Hyperexcitability of the peripheral nerve cause these symptoms, which are relieved by administration of Na channel blockers and immunotherapy. ⋯ The "VGKC antibodies" are now usually known as VGKC-complex antibodies. In general, LGI-1 antibodies are most common in limbic encephalitis with SIADH. CASPR-2 antibodies are present in the majority of patients with Morvan syndrome.