七年制医学课件 神经病学 12Mopathy.ppt

Myasthenia Gravis重 症 肌 无 力(see P341~346) YAN YONG Dep. of Neurology, the 1st Hospital, Chongqing University of Medical Science The myasthenia gravis (MG，重症肌无力) is a neuromuscular-transmission disorders神经肌肉 传递障碍, and an acquired immunological获得性免疫 disorder (probably immune mediated), of unknown cause, in which antibodies are directed against the postsynaptic突触后 acetylcholine 乙酰胆碱 receptor (AChR). This results in weakness and fatigability of skeletal muscle groups; the most commonly affected muscles are the proximal limbs肢体近端 and ocular and bulbar眼和延髓muscles. Myopathic disorders肌病 includes skeletal muscles by gene, Inflammation, Metabolic or toxicity: Muscular dystrophies肌营养不良:Duchenne’肌营养不良，Becker’s Congenital myopathies先天性肌病:mitochondrial肌病、肌管肌病等 Myotonic disorders 肌强直 Inflammatory myopathies炎症性肌病 AIDS Metabolic myopathies：Hypo-hyperkalemia,osteomalacia等 Endocrine myopathies：Hyper-or hypothyroidism等 Alcoholic myopathies Drug-induced myopathies：corticosteroids, certain β- blockers,chloroquine,clofibrate,emetrine,colchicine,and so on. Myoglobinuria 肌红蛋白尿: by muscle injury or ischemia, Neuromuscular junction: MG,lambert-Eaton syndrome A. How do occur the MG? In motor nerves, when the stimulus reaches the end of the nerve terminal acetylcholine(Ach) is released from vesicles via voltage-gated calcium channels. The Ach crosses the synaptic cheft and binds AchRs on the postsynaptic muscle end-plate membrane. This results in depolarization and subsequent contraction of muscle. The Ach is then broken down by acetyl- cholinesterase,which is bound to the basal lamina in the synaptic folds. A. How do occur the MG? The MG results from the Ach decreased by acetylcholinesterase overdose or the sensitive reduced of the Ach receptors. B. Clinical manifestation 1.MG can occur at any age. There are two peaks of incidence for MG, split by age and sex: a.Young women(20~40 yrs),who tend to have