肌肉病

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肌肉病 (Muscular Diseases)
教学目的
掌握
周期性瘫痪 (临床表现 治疗原则) •熟悉 进行性肌营养不良 临床表现 诊断
了解 周期性瘫痪:病因和发病机理, 进行性肌营养不良:主要临床分型
进行性肌营养不良 progressive muscular dystrophy (PMD)
Definiቤተ መጻሕፍቲ ባይዱion
Etiology and pathogenesis
• • • • DMD:X连锁隐性遗传, 基因位点在Xp21 BMD: X连锁隐性遗传 面肩肱型:常染色体显性遗传,在4q35 肢带型:常染色体隐性遗传,在第15号染 色体 • 远端型和眼咽型:常染色体显性遗传 • 眼肌型;多为常染色体显性遗传
Etiology and pathogenesis
Diagnostic Criteria
Becker muscular dystrophy
Elements
1. Symptoms like in Duchenne. Weakness of quadriceps femoris may be the only manifestation for a long time. Some patients have cramps that are mostly induced by activity. Contractures of the elbow flexors occur late in the course of the disease. It may present with myalgia and cramps, exercise intolerance and myoglobinuria, asymptomatic hyperckaemia, cardiomyopathy, or cognitive dysfunction. Exclusions: fasciculations, loss of sensory modalities. No wheelchair dependency before 16th birthday. There is a more than 5-fold increase of SCK activity (in relation to age and mobility). Electromyography: short duration, low amplitude, polyphasic action potentials, fibrillations and positive waves. Normal motor and sensory nerve conduction velocities.
• 进行性肌营养不良 • ——腓肠肌假性肥大
• 进行性肌营养不良 ——近段肌肉萎缩 翼状肩胛
Clinical findings
• Duchenne muscular dystrophy( DMD) 肌电图:肌源性损害 血清酶学:肌酸磷酸激酶(CK)、乳酸 脱氢酶(LDH)、 GOT和GPT增高 心电图:多为异常
9. Positive family history, compatible with X-linked recessive inheritance.
Differential diagnosis
• 少年近端型脊髓性肌萎缩症
青少年起病,表现为四肢近端对称性肌萎缩有 肌束颤;肌电图为神经原性损害,肌肉病理为 群组性萎缩,符合失神经支配。基因检测:5 q11-13上的SMN基因异常
7. Muscle biopsy: dystrophin of abnormal molecular weight and/or amount.
8. DNA: Becker-type mutation within the dystrophin gene, identical haplotype, involving closly linked markers, as in previous cases in the family.
• 慢性多发性肌炎
主要侵犯骨骼肌,以四肢近端力弱为主,无感 觉障碍,血清肌酶正常或轻度升高,肌肉病理 符合肌炎改变,表现为骨骼肌纤维广泛破坏, 单核细胞和淋巴细胞浸润;皮质类固醇疗效好
Treatment and Prevention
• 无特效治疗。以一般支持疗法为主。 • 药物治疗
三磷酸酰苷、肌苷、肌生注射液、甘氨酸 别嘌呤醇 小剂量的强的松 注射人胚肌细胞
• 假肥大型肌营养不良症(DMD)的基因位 点在Xp21染色体,编码抗肌萎缩蛋白 (dystrophin, Dys) • Dys分布于骨骼肌和心肌细胞膜的质膜面, 起到细胞支架的作用 • 基因缺陷导致肌细胞内缺乏Dys,引起功 能缺失
Etiology and pathogenesis
• 细胞膜学说:肌细胞遗传性某种代谢缺 陷使细胞膜即肌纤维膜结构和功能发生 改变。 • DMD的基因突变与细胞骨架蛋白有关 • utrophin的序列与Dys有80%相同,正常 时位于神经肌肉接头处。在PMD患者, utrophin位于肌纤维膜
Diagnostic Criteria
Duchenne muscular dystrophy Elements
6. Muscle biopsy: abnormal variation in diameter of the muscle fibres (atrophic and hypertropic fibres), necrotic and regenerative fibres, hyalin fibres, increase of endmysial connective and fat tissue. 7. Muscle biopsy: almost no dystrophin demonstrable, except for an occasional muscle fibre (less than 5% of fibres).
• 预防PMD:检出携带者和产前诊断
周期性瘫痪 periodic paralysis
离子通道病(ion channel disease)
• 离子通道功能异常 • 主要侵及神经和肌肉系统,心脏和肾脏 等器官也可受累 • 离子通道病包括;低钾型周期性瘫痪 (钙离子通道异常)、先天性重症肌无 力(AChR基因突变)、先天性副肌强直 症(钠通道异常)、高钾型周期性瘫痪 (钠通道基因突变)
• 遗传性肌肉变性病 • 起病隐袭,进展缓慢
• 对称性肌无力和肌萎缩
• 头面部和肢体肌肉易受累,也可累及心 肌
Classification of PMD
• 假肥大型: Duchenne muscular dystrophy (DMD) Becker muscular dystrophy (BMD) • 面肩肱型 Facioscapulohumeral muscular dystrophy • 肢带型 (Limb-girdle muscular dystrophy) • 眼咽型 (Oculopharyngeal dystrophy) • 远端型 (Distal dystrophy) • 眼肌型 (Ocular dystrophy)
Clinical findings
• Becker muscular dystrophy(BMD) 具有DMD必有的特征 发病年龄较晚(12岁以后) 病情进展缓慢(病程可达25年以上) 多不伴有心肌受累或仅轻度受累 预后较好
Clinical findings
• facioscapulohumeral muscular dystrophy 发病年龄:以青春期为多见 早期为面部表情肌无力和萎缩,逐步累 及肩胛带、三角肌、肱二头肌和肱三头 肌等 一般不伴心肌损害 肌电图为肌源性损害 血清CK和LDH等可正常或轻度升高
• • • • • • • 临床表现 遗传方式,患者多有家族史 血清酶学 肌电图:肌源性损害 肌肉病理检查 基因检测 抗肌萎缩蛋白检测
Diagnostic Criteria Duchenne muscular dystrophy Elements
1. Symptoms are present before the age of 15 year.
2. Clinical signs comprise progressive symmetrical muscular weakness; proximal limb muscles more than distal muscles; initially only lower limb muscles. Calf hypertrophy is often present. 3. Exclusions: fasciculations, loss of sensory modalities. 4. Loss of unassisted ambulation before the age of 13 years. 5. There is at least 1 10-fold increase of serum creatinine kinase(SCK) activity (in relation to age and mobility).
Clinical findings
• limb-girdle muscular dystrophies 多在10~20岁发病,病情进展缓慢 首发症状为骨盆带肌肉萎缩,亦可累及 肩胛带肌肉,头面部肌肉不受累,可伴 有腓肠肌假性肥大 肌电图和肌活检示肌源性损害 血清肌酶常显著升高
Diagnosis
Etiology and pathogenesis
• Dystrophin(Dys)是肌细胞膜细胞骨架 的主要成分,与肌纤维膜糖蛋白紧密结 合为抗肌萎缩蛋白结合蛋白(dystrophinassociated protein, DAP),与细胞外基质 蛋白联结。 • Dys减少引起上述联结的失调,导致肌纤 维膜不稳定,引起肌纤维坏死
8. DNA: Duchenne-type mutation within the dystrophin gene, identical haplotype, involving closly linked markers, as in previous cases in the family. 9. Positive family history, compatible with X-linked recessive inheritance.
2. 3. 4.
5.
Diagnostic Criteria
Becker muscular dystrophy
Elements
6. Mucscle biopsy: abnormal variation in diameter of the muscle fibres (disseminated or small groups of atrophic and hypertropic fibres), regenerative fibres, mostly disseminated necrotic fibres, Dependent on stage and course of the disease, there may be a minor degree of grouping of histochemical fibreb types and increase of connective and fat tissue.
Pathology
• 基本病理改变:肌纤维坏死和再生,肌 膜核内移,出现肌细胞萎缩和代偿性肥 大镶嵌分布 • 肌细胞间质内有脂肪和结缔组织增生 • 肌活检组化检查见Dys缺失或异常
Clinical findings
• Duchenne muscular dystrophy( DMD) 儿童期起病,均为男性 肌无力起自躯干和四肢近端。Gower征 为特征性表现。 四肢近端肌萎缩明显,双腓肠肌假性肥 大 可有心肌受累,智力发育迟缓
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