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This Concept Map, created with IHMC CmapTools, has information related to: Skeletal Muscle, Skeletal Muscle Myopathies due to IEMs MITOCHONDRIAL (OXPHOS DZs) 1/5 of oxphos proteins are mito-encoded-maternal Young adult onset Proximal mm weakness External ophthamoplegia in some MORPH-abnl mito aggregates ->blotchy red mm fibers -RAGGED RED FIBERS -mito are red w/ Gomori -"parking lot inclusions" Class I mutations-nuclear DNA -Leigh syndrome, Barth syn Class II muts-pt muts in mtDNA MERRF, LHON, MELAS Class III-del, duplicated mtDNA -CPEO, KSS, Skeletal Muscle Inflammatory SYSTEMIC INFLAM DZs, Skeletal Muscle Ion Channel Myopathies CHANNELOPATHIES-AD -myotonia -relapsing hypotonic paralysis (induced by cold, exercise, high CHO meal) -some variants w/ K ABNLities GENETICS -chrom 17 in hyperkalemic -Na channel protein -hypokalemic-voltage-gated Ca channel -chrom 7 MORPH-PAS(+) intermyofibril vacuoles -dilated sarcoplasmic reticulum, Skeletal Muscle Muscular Dystrophies X-LINKED MUSC DYSTROPHY (DUCHENNE, BECKER MD) BMD-near NL life span, slower DMD-most common, severe -onset 5yo, wheelchair 10yo death 20s -weakness in pelvic girdle -> shoulder -big calf-pseudohypertrophy-fat, CT -changes in heart->HF, arrhythmias -subendocard fibrosis -some w/ mental retardation -serum CK increased early on Death via resp insuff, pulm infx, cardiac decompensation GENETIC-Xp21-dystrophin deletions -1/3 w/ new mutation -BMD w/ mutations->ABNL protein -maintains memb integrity MORPH-varied fiber size, sm and giant -internalized nuclei -degen, necrosis, phagos of fibers -regen of fibers, CT proliferation, Skeletal Muscle Muscular Dystrophies AUTOSOMAL -LIMB GIRDLE MD-like DMD -AD (type 1) or AR (2) -SARCOGLYCAN muts in 4/10 -interact w/ dystrophin, Skeletal Muscle NMJ MYASTHENIA GRAVIS-AI -loss of ACh-receptors -ABs to AChR can be transferred ->inc'd rate of AChR degradation -if មyo, mostly FEMALE -if ᡠ M=F -thymic hyperplasia in 65% MORPH-disuse type 2 atrophy -ICs along post-syn membrane -AB level doesn't corr to severity CLINICAL-weakness -start w/ extraocular mm -drooping eyelids -may also be generalized -FLUCTUATING WEAKNESS -DTRs preserved -exacerbated by other illnesses -anti-AChE Rx help, prednisone, plasmapheresis, thymoma resection Dx-edrophonium-should improve (Tensilon test), Skeletal Muscle Denervation Atrophy -due to ant horn cell path SPINAL MUSCULAR ATROPHY-AR Infantile Motor Neuron Dz -AHC destruction -begins in childhood, teens GENETICS-chrom 5 -survival motor neuron SMN gene -deletion in 98% pts -most severe w/ NAIP deletion -(neuronal apop inhib protein) MORPH-lots of atrophic fibers -often panfascicular -scattered large fibers (2-4x NL) CLINICAL- WERDNIG-HOFFMAN DZ (SMA-1) -birth onset, death w/in 3yr SMA 2 - 3-15 mos, 4yr survival SMA 3 - ɮyrs ->adulthood, Skeletal Muscle Toxic DRUG-INDUCED Steroid myopathy (exogenous or Cushing) -prox mm weakness, atrophy -may have NL Type 1, atrophic Type 2 Chloroquine-vacuoles in myocytes -autophagic memb-bound vacs -curvilinear bodies -mostly in Type 1 fibers, Skeletal Muscle Inflammatory NON-INFX INFLAM MM DZ: POLYMYOSITIS DERMATOMYOSITIS INCLUSION BODY MYOSITIS, Skeletal Muscle NMJ LAMBERT-EATON MYASTHENIC - AI SYNDROME -paraneoplastic process -60% w/ SMALL CELL CA OF LUNG -can also be w/out CA ->prox mm weakness + AUTONOMIC DYSFCN (dry mouth, impotence) -DTRs NL NL AChR content FEWER ACh VESICLES RELEASED -some pts w/ ABs against presyn Ca channels Dx-no help w/ edrophonium -BUT enhanced neurotransmission w/ repetitive stimulation, Skeletal Muscle Myopathies due to IEMs LIPID -problems w/ carnitine xport system -in beta-oxidation of fatty acids -carnitine def mostly from MCAD def ->lipid droplet accumulation esp Type 1 fibers Sx-WEAKNESS -variable age at onset CPT II deficiency->MYOGLOBINURIA-DARK -teens, young adults -episodic, acute myonecrosis post-exercise CPT I def - more severe-infantile, Skeletal Muscle Congenital CENTRAL CORE DZ - AD, sporadic NEMALINE MYOPATHY - AR, AD CENTRONUCLEAR MYOPATHY - AR, X Common to most: -early life onset -nonprogressive or slow -proximal or generalized mm wkness -hypotonia-floppy babies -arthrogryposis-severe jt contractures, Skeletal Muscle Inflammatory INFECTIOUS MYOSITIS, Skeletal Muscle Toxic THYROTOXIC MYOPATHY -acute or chronic PROXIMAL weakness -exophthalmic ophthalmoplegia -swollen eyelids, edema, diplopia -extraocular mm only -myofiber necrosis, regen, lymphos Hypothyroidism-cramping, aching mm -mvmts, reflexes slowed -fiber atrophy -inc'd internal nuclei -glycogen aggs, MPS deposits in CT Thyrotoxic Periodic Paralysis -episodic weakness w/ hypokalemia -M=4xFM; JAPANESE, Skeletal Muscle Ion Channel Myopathies MALIGNANT HYPERPYREXIA (MALIG HYPERTHERMIA) -dramatic hypermetabolism ->tachycard, tachypnea, mm spasms->hyperpyrexia -via halogenated inhal anesthetics + succinylcholine -can also occur in hered mm dzs -suscep w/ genes for channels: voltage-gated Ca, L-type Ca, ryanodine receptor, Skeletal Muscle Tumors RHABDOMYOMA RHABDOMYOSARCOMA, Skeletal Muscle Muscular Dystrophies MYOTONIC DYSTROPHY-AD -sustained invol contraction -trouble releasing grip -ANTICIPATION-younger w/ each generation GENETICS-19q13.2-myotonin protein kinase -CTG trinucleotide repeat MORPH-can resemble DMD -inc'd internal nuclei -RING FIBER -atrophy of TYPE I FIBERS -pathology in INTRAFUSAL FIBERS (SPINDLES) CLINICAL-late childhood-ABNL gait -weak dorsiflexors -CATARACTS in almost all -facial mm atrophy -frontal balding, gonadal atrophy -cardiomyopathy, dementia -sm mm involvement -dec'd IgG, ABNL GTT -if congenital - maternal inher, Skeletal Muscle Toxic ETHANOL MYOPATHY -via binge drinking -acute toxic syndrome: rhabdomyolysis->myoglobinuria -can->renal failure -generalized or localized pain -proximal mm weakness MORPH -swollen myocytes, fiber necrosis -myophagocytosis, regeneration -some denervation