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51 Cards in this Set
- Front
- Back
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What is the definition of a myopathy?
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A disease in which the structure of function of muscle is compromise
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What is the definition of muscular dystrophy?
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An inherited, progressive disorder of muscle, usually due to an abnormality in a structural protein
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What are the different kinds of muscuar dystrophies?
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Dystrophin deficiency
Limb-girdle muscular dystrophy Other reginal muscular dystrophies Myotonic dystrophy |
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What are the epinems associated with dystrophin deficiency?
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Duchenne's: the most serious
Becker's: less serious |
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What are the clinical features of Duchenne's Muscular dystrophy?
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Boys only
Normal at birth At the onset of walking -Remain clumsy longer than normal -Gower's sign -Can't run, jump Calf pseudohypertrophy: calves are filled with connective tissue |
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What is Gower's sign. Who shows it?
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Kids march up the legs with hands to stand up off the floor
Boys with Duchenne's Muscular dystrophy |
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As a kid ages, what are the different stages of Duchenne's Muscular dystrophy?
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2-6: Gain motor skills, they appear to improve
6-7: start to fall without warning 8-10: lose ability to climb stairs, stand from the floor 12: wheelchair dependent |
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What are the other systemic problems that are present in kids with Duchenne's Muscular dystrophy?
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Deterioration in respiratory function due to weakness, scoliosis
Cardiac abnormalities Cognitive impairment |
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What are some of the cardiac abnormalities found in Duchenne's Muscular dystrophy?
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Wall thickness, wall motion, valve motion abnormalitis
Intra-atrial conduction abnormalities |
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What are the two types of dystrophin deficiencies?
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Duchenne's
Becker's |
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What are the clinical features of Becker's?
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Average onset of muscular symptoms is at 12...can be as late as 40
Can walk until the late teens, may not need a wheelchair until 20's Cardiomyopathy is common Normal cognition |
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What's the prognosis for the different dystrophin deficiency?
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Duchenne's:
die in late teens/twenties from respiratory failure (usually) or cardiac failure (occasionally) Becker's: Die in the 5th decade, sometimes later |
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What's the pathology behind the dystrophin deficiency?
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Lack of the dystrophin protein (duchenne's) or mutations in it (Becker's) causes a lack of stabilization of the muscle fibers
As a result, you get focal tears in the muscle, resulting in more Ca influx, which leads to more tearing, which leads to necrosis due to the activation of proteolytic enzymes, ultimately |
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What changes in the muscles do you see in dystrophin deficiency?
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Initially:
-Degeneration and phagocytois of single muscle fibers or groups of fibers -Stimulation of regeneration: basophilia of cytoplasm, hyperplasia and nucleolation of nuclei As the disease progresses: -Loss of muscle fibers -Residual fibers that are variable in size -Fibrosis -Increased lipocytes |
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What is the histology of muscles with dystrophin deficiency?
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Lack of striation
Nuclei in the middle of the cells Lots of connective tissue LATE: -Adipocytes -Fibrosis |
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What genetic changes take place during Duchenne's? Beckers?
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Duchenne's: deletion of the dystrophin gene
Becker's: dystrophin mutations, but preservation of the correct ORF |
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What tests should you order for a diagnosis of dystrophin deficiency?
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Blood levels: increased creating kinase
EMG changes Genetic testing of the dystrophin gene |
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What's the management of the dystrophin deficiencies?
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Prednisone for Duchenne's, not for Becker's
-Benefit lasts for 3 years Supportive care |
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What is the cause of the limb-girdle muscular dystrophies?
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Mutations in the dystrophin-associated proteins, other muscle proteins
Based on the proteins mutated, you'll get a specific pattern of muscle involvement |
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What are some of the other regional muscular dystrophies?
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Emery-Dreifuss
Facio-scapulo-humeral Oculopharyngeal |
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What is the inheritance of Emery-Dreifuss regional muscular dystrophy? Where does it effect?
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X-linked recessive
Cardiac involvement |
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What is the inheritance of Facio-scapulo-humeral regional muscular dystrophy? Where does it effect?
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Autosomal dominant
Face and shoulder girdle, legs THE FOREARMS ARE SPARED: THEY LOOK LIKE POPEYE |
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What is the inheritance of oculopharyngeal regional muscular dystrophy? Where does it effect?
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Autosomal dominant (prominent in French-canadians)
Eye muscle weakness, ptosis, then dysphagia |
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What are the clinical features of myotonic dystrophy?
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Autosomal dominant
Weakness, atrophy Myotonia Multisystem abnormalities |
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What does it mean if someone has myotonia?
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You can't release the muscle after you contract it:
-Can't let go of the door handle -Legs freeze |
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What is the pattern of weakness in myotonic dystrophy?
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In order
Face: Ptosis Muscles of eye and mouth closure Temporalis Arms: Small muscles of hands Extensor muscles of forearms Neck: SCM Muscles of the larynx, pharynx |
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What kind of facial appearance does someone with Myotonic dystrophy have?
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Hatchet mouth
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What are some of the multisystem abnormalities that are present in myotonic dystrophy?
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Cataract
Cardiac conduction defects/arrhythmia Testicular atrophy Early male baldness DM Mild/moderate mental retardation |
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What's the pathogenesis of myotonic dystrophy?
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Elongated trinucleotide repeat (CUG
RNA transcripts stop splicing, leading into problems with receptors, ion channels It's this that causes the multisystem problems |
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What tests should you order if you suspect someone has myotonic dystrophy?
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EMG (for myotonia)
Genetic testing |
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How do you treat myotonic dystrophy?
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It's supportive
If the myotonia is bad enough, you give drugs that effect their sodium channels |
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What are some of the non-dystropic hereditary myopathies?
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They all impact energy metabolism
Abnormal glycogen metabolism Phosphofructokinase deficiency Mitochondrial myopathies Channelopathies |
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What causes problems in someone with abnormal glycogen metabolism?
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They cramp with exercise,but they're fine at rest
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What are the different kinds of abnormal glycogen metabolism?
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McArdles: myophosphorylase deficiency
CPT deficiency Acid maltase deficiency |
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How do you differentiate between McArdle's and CPT deficiency?
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McArdle's: you get a 2nd wind becase you can use FFAs
CPT: the deficiency is in the utilization of FFAs, so you don't get a second wind |
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What are the clinical features of acid maltase deficiency?
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Weakness that slowly progresses
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What other myopathy is similar to PRK deficiency?
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McArdle's
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What are the features of mitochondrial myopathies?
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migraine
Ataxia Periodic paralyses |
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What are the features of the channelopathies?
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Periodic paralyses
Myotonic disorders |
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Whatare some of the acquired metabolic myopathies?
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Hypo, hyperthyroidism
Hyperparathyroidism CUSHING'S EXOGENOUS STEROIDS Chronic alcohol use |
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What are some of the inflammatory acquired myopathies?
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Dermatomyositis
Inclusion body myositis Polymyositis |
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What are some of the clinical features of dermatomyositis and polymyositis?
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Symmetric proximal muscle wasting, weakness
Gradual progression Pain is sometimes present, but not severe |
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What findings are common in dermatomyositis?
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Rash on the face and hands
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What are the clinical features of inclusion body myositis?
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Forearm flexors, knee extensors
Asymmetric Dysphagia Facial muscle involvement |
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If you're young, what inflammatory myopathy do you get? After 50?
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Kids: dermatomyositis
After 50: IBM |
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If you're old and you've got dermatomyositis, what do you have to be concerned about?
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SYSTEMIC MALIGNANCIES!
It's present in 10-20% of people with this guy |
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What is the pathology that is present in the inflammatory myopathies?
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-Segmental muscle fiber necrosis
-Muscle fiber regeneration -Mononuclear cell inflammation |
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What's the difference between the pathology of polymyositis/IBM and dermatomyositis?
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PM/IBM: cell mediated
DM: humoraaly mediate |
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What are the changes that take place in the muscle fibers in IBM? What other disease processes show these proteins?
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Vaculolar inclusions in the muscle fibers of beta amyloid, tau, TDP-43!!
Alzheimers, other neural diseases |
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What tests should you order to make a diagnosis of the inflamamtory myopathies?
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Blood levels: Increased CK
EMG: Myopathic changes, inflammatory characteristics MUSCLE BIOPSY IS GOLD STANDARD |
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What kinds of inflammatory myopathies can you treat? What do you use?
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DM, PM: prednisone
IBM you can't do anything for In all of them, give symptomatic treatment |
