Electromyography is an important element of clinical diagnostics and often helps physicians to find the appropriate diagnosis between different neuromuscular disorders. By having a closer look on electromyographical findings in myasthenia gravis, myopathic changes predominantly occur in proximal muscles next to a pathological decrement, which can underscore the diagnosis of this neuromuscular disorder. In polymyositis, next to myogenic changes more often signs of spontaneous activity like fibrillations and complex repetitive discharges are found as
signs of muscle inflammation. Myasthenia gravis (MG) is a disease with a prevalence of 20/100000 patients. It is caused by autoantibodies against postsynaptic acetylcholine receptors (AChR) or against muscle specific receptor tyrosine kinase (MuSK). Polymyositis (PM) is a more rare (incidence of 5-10/100000 patients per year) systemic auto-inflammatory disease of skeletal muscles with perivascular lymphocyte infiltration of cytotoxic CD8 (+) lymphocyteswith MHC I positive fibres. Polymyositis (PM) is a more rare systemic auto-inflammatory disease of skeletal muscles with perivascular lymphocyte infiltration of cytotoxic CD8 (+) lymphocytes with MHC I positive fibres.
Last date updated on July, 2014