Neuromyotonia.
There is increasing evidence that autoimmunity is implicated in the pathogenesis of peripheral nerve hyperexcitability (neuromyotonia, NMT and Cramp-fasciculation syndrome C-FS ) and in Maladie de Morvan in which CNS features are also present. All three conditions can associate with thymoma, myasthenia gravis and other autoimmune disorders, and can often respond to plasma exchange. In NMT, patient's plasma or IgG can transfer the electrophysiological features to mice, and can reduce voltage-gated potassium channel currents in vitro. Antibodies to voltage-gated potassium channels can be detected in the serum of many patients who have peripheral nerve hyperexcitability, and also in those with Maladie de Morvan. These latter patients have clinical features similar to limbic encephalitis in which VGKC antibodies can also occur. Thus neuromyotonia, cramp-fasciculation syndrome and Maladie de Morvan can occur as antibody-mediated autoimmune ion channelopathies like myasthenia gravis and the Lambert-Eaton myasthenic syndrome. These discoveries should aid diagnosis and offer new approaches to treatment.
Department of Clinical Neurology, University of Oxford, Radcliffe Infirmary, Oxford OX2 6HE, UK. john.newsomdavis@btinternet.com
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D000818:Animals; D001323:Autoantibodies / Q000032:analysis; D001327:Autoimmune Diseases / Q000188:drug therapy / Q000503:physiopathology; D004594:Electrophysiology; D005207:Fasciculation / Q000188:drug therapy / Q000503:physiopathology; D006801:Humans; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology; D009120:Muscle Cramp / Q000188:drug therapy / Q000503:physiopathology; D009125:Muscle Relaxants, Central / Q000627:therapeutic use; D009222:Myotonia / Q000188:drug therapy / Q000503:physiopathology*; D015221:Potassium Channels / Q000276:immunology / Q000502:physiology; D013595:Syringomyelia / Q000188:drug therapy / Q000503:physiopathology
D001323:Autoantibodies; D007473:Ion Channels; D009125:Muscle Relaxants, Central; D015221:Potassium Channels