CH45: Muscle Flashcards by Robert Sarmiento

Muscles make how many percent of body weight of human beings (p. 1405)

40%

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interdigitating filaments
contractile proteins
structural proteins
regulatory proteins

(p. 1405)

myofilaments
actin and myosin
titin and nebulin
tropomyosin and troponin

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Basic physiologic unit in all reflex, postural and voluntary activities (p. 1405)

Motor unit

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Type I vs Type 2 Muscles (p. 1406)

Type 1: increase oxidation, decrease glycogen stores

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percussion myotonia vs myoedema (p. 1410)

myoedema are electrically silent

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brief fascicular contraction that is induced by tapping a anormal or partially denervated muscle (p. 1410)

idiomuscular contraction

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In this type of contracture, the muscles remain shortened for many minutes because of failre of the metabolic mechanism necessary for relaxation (p. 1410)

trye physiologic contracture

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There is fibrosis of muscle and surroinding tissues as a result of ischemic injury usually after a fracture of the elbow (p. 1410)

Volkmann contracture

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Form of fibrous contracture that is found in newborns involving two features: fibrosis of muscle and neural or muscular apparatus that results in muscular weakness (p. 1410)

Arthrogryposis

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Triad of Satayoshi syndrome (p. 1411)

pianful leg cramps
alopecia universalis
diarrhea

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Puffy face and tender muscles
Biopsy: segmental necrosis, interstitial infilammatory infiltrates, predominance of eosinophils
EMG: profuse fibrillation potentials
(p. 1415)

Trichinosis

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Treatment for Trichinosis

No treatment is required in most cases.

If with severe cases: thabendazole, predinisone or albendazole

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Weakness, wasting, myalgia, failure of other organs, increased CK
focal infammation where parasitic pseudocyst ruptures

Toxoplasmosis

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Treatment for Toxoplasmosis (p. 1415)

Sulfadiazine with Pyrimethamine or trisulfapyramide

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Parasitic infection wherein there is dramatic pseudohypertrophy of calf muscles (p. 1415)

cystecircosis

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HIV treatment with myopathy as side effect (p. 1416)

Zidovudine

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Pattern of weakness in early HIV patients (p. 1416)

painless wekaness of girdle and proxima limb muscles
Elevated CK
EMG: fibrillations, brief polyphasic motor units, complex repetitive discharges

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Pathologic findings in Zidovudine- induced myopathy (p. 1416)

Presence of ragged red fibers

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representative example of inflammatory myopathy
painbless weakness of the proximal limb muscles
ocular muscles are rarely affected
muscles are not tender
dermatologic findings:localized or diffuse erythema, maculopapular eruption, scaling eczematoid dermatitis, exfoliative dermatitis (p. 1417)

Dermatomyositis

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Dermatologic findings in dermatomyositis (p. 1417)

Gottron papules
- red, raised, papules on the elbows, knuckles and distal and proximal IPjoints

Heliotrope rash

Shawl sign

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Other physical findings in dermatomyositis (p. 1418)

periarticular and subcutatneous calcifications

Reynaud phenomenon

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Also check in patients with polymyositis (p. 1418)

Cardiac abnormalities
Interstitial lung disease with anti- Jo
Carcinoma (lung and colon in men; breast and ovarian in women)

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Gait in pediatric patients with dermatomyositis (p. 1418)

tiptoe gait because of the contractures of flexors of the ankles

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Specific antibodies in severe, necrotizing inflammatory myositis (p. 1419)

SRP (cytoplasmic ribonucleoprotein complex)

Mi-2 (nuclear helicase)

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anti tRNA synthetase (p. 1419)

anti-Jo

EMG findings in DM and PM (p. 1420)

polyphasic units that simulate denervation- reinnervation changes, juxtaposed with myopathic motor units

DM vs PM pathological findings (p. 1420)

DM- perifascicular muscle fiber atrophy PM- scattered Inflammatory infiltrates DM- perimysial connective tissue PM- endomysium

Principal changes in idiopathic PM (p. 1420)

widespread destruction of segments of muscle fibers with an inflammatory reaction phagocytosis of muscle fibers by mononuclear cells and infiltration with a varying number of lymphocytes and lesser numbers of other mononuclear and plasma cells

DM vs PM re etiology and pathogenesis (p. 1421)

PM- large number of activated T cells, mainly CD8 class whereas B cells are sparse DM- the percentage of B cells at all sites is significantly higher than it is in PM

Treatment for DM or PM (p. 1421)

prednisone 1mg/kg | acute or severe cases: MPPT 1g IV each day for 3 -5 days

Prognosis of DM or PM (p. 1422)

Good | extent of recovery depends on acuteness and severity of the disease

steadily progressive, painless, muscular weakness and modest atrophy usually distal in the arms and both proximal in the legs (p. 1422)

Inclusion Body Myositis

Contrast DM and IBM (p. 1422)

The deltoids are spared and the thumb flexors are weak in IBM (opposite to PM and and DM)

IBM vs ALS (p. 14223)

the EMG changes are restricted to the weakend muscles

Denominative finding in IBM (p. 1423)

intracytoplasmic, subsarcolemmal vacuoles, eosinophilic inclusions

Cystosolic antibodies found 2/3 of patietns with IBM (p. 1423)

anti-cN1

Treatment of IBM (p. 1423)

difficult; not responded in any consistent fashion to treatment with corticosteroids

Antibody directed to the signaling of TGF-b has shown the improvement of muscle mass; but no definitive clinical effect yet.

Bimagrumab

Features that virtually exclude myositis (p. 1424)

1. lack of reduced peak power of contraction | 2. normal EMG, serum enzymes and muscle biopsy

In eosinophilia-myalgia syndrome, severe eosinophilia and myalgia were found following the ingestion of which amino acid? (p. 1425)

L- tryptophan

``` dystrophy with rapid progressive course X linked recessive almost exclusively in amles symptoms show before learning to walk greatly elevated CK waddling gait ```

Duchenne muscular dystrophy

Muscles that are large in DMD (p. 1427)

gastrocnemii lateral vasti deltoids

Waddling gait in DMD is due to (p. 1427)

weakness of gluteus medius

Posture of DMD (p. 1427)

lumbar lordosis hip flexion and abduction knee flexion plantar flexion

ECG findings in DMD (p. 1427)

prominent Rwaves in R prevordial leads and deep Q waves in L precordial and limb leads

EMG findings in DMD (p. 1427)

fibrillations, positive wavesw, low- amplitude and brief polyphasic MUP, high frequency discharges

MD onset is later patient can walk into adult life retain their ability to raise the head fully off the bed (p. 1428)

Becker Muscular Dystrophy

most distinctive features of DMD and BMD (p. 1428)

prominent segmental degeneration and phagocytosis of single muscle fibers or groups of fibers and evidence of regeneerative activity necrosis excites a regenerative or restorative process which explains the forking of fibers and clustering of small fibers with prominent nuclei hyalinization of sarcoplasm contraction bands, expressive of the irritability of dystrophic muscle

Hypertrophy of muscle in DMD and BMD due to (p. 1428)

work-induced enlargement of the remainign sound fibers in the face of adjacent fiber injury

largest gene known to human, spanning more than 2Mb of DNA (p. 1428)

Dystrophin

X-linked muscular dystrophy special feature is muscle contractures early appearance of contractures in the flexors of the elbow, extensors of the neck and posterior calf muscles (p. 1429)

Emery-Dreifuss Muscular Dystrophy

Constituent of the nuclear membrane, encoded by EMD on the X chromosome (p. 1429)

emerin

slowly progressive dystrophy, with periods of complete arrest age of osnet 6-20 years old Weakness and atrophy are major physical findings present with difficulty raising the arms deltoids may seem to be unusually large and strong amyoplasia is associated (p .1430)

Fasciohumeral Muscular Dystrophy

Biceps waste less than the triceps and the brachioradialis muscles even less. Hence, upper arm may be thinner than fore arm. (p. 1430)

Popeye effect

FSHD1 gene (p. 1431)

DUX4, on tip of chromosome 4q

Early onset, relatively rapid progression of FSH Facial diplegia sensorineural deafness exudative retinal detachment (p. 1431)

Coats disease

Patients that dont fit to DMD, BMD, GSH; lack hypertrophy of calves

LGMD LGMD1- dominant 6 LGMD2- recessive 19

Achilles tendon contracture Very high serum CK levels Dysferlin

Calpainopathy

Problems of levators of the eyelids Simultaneous invlvement of all EOM permits the eye to remain in a central position hence diplopia is uncommon Hutchinsonian facies (p. 1433)

Kearns Sayre Syndrome

Kearns Sayre mutations (p. 1434)

twinkle ANT1 POLG

Oculopharyngeal Dystrophy gene (p. 1434)

PABN1

Unstable nucleotide sequence in Myotonic Dystrophy (p. 1434)

CTG

Myotonia +distal weakness Cardiac arrthythmias Small muscles of the hands along with extensor muscles of forearms atrophy hatchet facies Swan neck Progressive frontal alopecia, testicular atrophy, gynecomastia(p. 1434)

Myotonic Dystrophy 1

Myotonic dystrophy vs Myotonia congentia (p. 1434)

In myotonic dystrophy, the characteristic hypertrophy in myotonia congenita is absent

Pathologic feature in Myotonic Dystrophy (p. 1436)

peripherally placed sarcoplasmic masses and circular bundles of myofibrils (ringbiden)

Most prominent features of congenital myotonic dystrophy (p. 1436)

profound hypotonia | facial diplegia at birth

T/F Like the expanded CTG repeat in myotonic dystrophy, the CCTG expansion in PROMMis assocaited with intranuclear accumulation of the expanded RNAtranscript and like the CTG repeat of myotonic dystrophy, the CCTG segments do not code for a protein (p. 1436)

adult life onset weakness and atrophy of the leg muscles most prominent in the peroneal or the gastroneius and soleus muscles dysferlin

Miyoshi Myopathy

The major congenital muscular dystrophies share an improtant biologic attriubte: (p. 1439)

1. abnormality of a protein that binds to the dystrophin complex (laminin or merosin) 2. abnormality of a protein in the Golgi apparatus taht is important in processing proteins

Predominant isoform of alpha-laminin (p. 1439)

Merosin

Treatment of Myscular Dystrophies (p. 1440)

Prednisone 0.75mg/kg daily

This drug is shown to reduce myotonia (p. 1441)

Mexiletine

Enzyme that initiates the metabolism of glycogen (p. 1442)

Myophosphorylase

T/F All the glycogenoses are inherited as autosomal recessive traits (p. 1442)

Skeletal muscles are weak and hypotonic Tongue is enlarged giving the infant a cretinoid appearance Pompe Disease (p. 1442)

Acid maltase deficiency

Treatment for Acid Maltase deficiency (p. 1443)

Enzyme replacement therapy

Primary deficiency of myophophyrylase (which prevents the conversion glycogen to glucose 6-phosphate) Primary deficiency of phosphofructokinase deficiency (which converts glucose 6 phosphate to glucose 1 phosphate) p. 1443

McArdle disease Tarui disease

Test for McArdle disease and Trui disease (p. 1443)

forearm ischemic exercise test | lactate fails to rise

Treatment for McArdle and Tarui (p. 1444)

Sucrose 75g in a beverage

Carnitine is derived from (p. 1445)

lysine and methionine

Progressive lipid storage myopathy and cardiomyopathy No dicarboxylic aciduria (p. 1447)

Primary systemic carnitine deficiency | TX: L carnitine 2 to 6 g/d

Differentiate the Carnitine Palmitoyltransferase Deficiency (p. 1447)

I necrosis of muscle fiers; between attacks normal muscles IIA lipid bodies in liver IIB lipid bodies in liver, heart, kidneys, skeletal muscle

Recently, this drug has been helpful in patients with mild CPTII (p. 1447)

Bezafibrate

Muscle of the pelvic girdle and thigh are weakend more than others in thyroid myopathies (p. 1448)

Basedow paraplegia

EOM affected in thyroid myopathy (p. 1449)

inferior and medial recti

T/F pupillary and ciliary muscles are always spared (p. 1449)

How many percent of patients with MG have hyperthyroidism (p. 1449)

Cretinism +muscle abnormalities (p. 1450)

Kocher Debre Semelaigne syndrome

Myxedema + muscle hypertrophy (p. 1450)

Hoffman syndrome

Speed of contractile process is related to __ Speed of relaxation depends on ___ (p. 1450)

myosin adenosine triphosphatase | release and reaccumulation of calcium

EMG findings of corticosteroid myopathy (p. 1450)

mildly myopathic-- small and abundant action potentials but no fibrillations

Noted to be related in the incidence of critical illness myopathy (p. 1450)

intake of neuromuscular blockade

Identifying histologic feature in patients with critical illness myopathy (p. 1451)

striking loss of thick myosin filaments. Sevvere degrees of muscle necrosis; accompanied by elevated CK levels and myoglobinuria with renal failure

In hypoparathyroidism, this is prominent. | In hypo and hyperparathyroidism, this is prominent. (p. 1451)

Muscle cramping | Tetany

Biopsy findings in weakness in acromegaly (p. 1452)

atrophy and reduced numbers of type 2 fibers; necrosis of only a few fibers

statin myopathy noted to be worse when this drug was added (p. 1453)

gemfibrozil

gene carrying risk fo statin myopathy (p. 1453)

SLCO1B1

Pathologic finding in Colchicine neuromyopathy (p. 1454)

rimmed vacuoles on Gomori trichrome strain more central in the muscle fibers than those seen with IBM

Manifestation of acute alcohol myopathy (p. 1454)

severe pain, tenderness, edema of the muscles of the limbs and trunk

Muscles noted to be absent in amyoplasia (p. 1455)

``` Palmaris longus Pectoralis Trapezius Serratus anterior Quadriceps femoris ```

Agenesis of the pectoral muscle with scoliosis, webbed fingers, underdevelopment of ipsilateral arm and hand (p. 1455)

Poland syndrome

Gene associated with floppy infant and risk for malignant hyperthermia (p. 1457)

RYR1 Mutation of Central Core myopathy

EMG findings of central core myopathy (p. 1457)

brief, small- amplitude motor unit potentials with normal interference pattern

Unique feature of central core myopathy (p. 1457)

central portion of each musce fiber of a dense, amorphous condensation of myofibrils or myofibrillar material

Unlike the central core myopathy, the muscles of the trunk and limbs (proximal > distal) as well as the facial, lingual, and pharyngeal muscles are strikingly thin and hypoplastic. (p. 1457)

Nemaline (Rod-Body) Myopathy

Nemaline Rod Myopathy are genetically heterogenous but 20% are due to mutations in (p. 1458)

ACTA1

Myopathy with hypotonia, weakness. Limbs remain flexic throughout life. Motor development is slowed. Cerebral abnormality with seizures is noted. (p. 1458)

Centronuclear Myopathy

EMG findings in muscle cramps (p. 1460)

high frequency, high voltage action potentials and precramp phase with runs of activity in motor units

Mechanism of cramping is obscure but this enzyme is controversially included (p. 1460)

myoadenylate

Treatment for cramps (p. 1460)

Quinin sulfate but no longer recommended due to ventricular arrhythmia Diphenhydramine hydrochloride Phenytoin Carbamazepine

``` Universal alopecia Amenorrhea Intestinal malabsorption- diarrhea Epiphyseal destruction Retarded growth (p. 1460) ```

Stayoshi syndrome

Proximal muscle pain, sometimes asymmetrical Common in middle age Every movement reported is stiff and painful (p. 1461)

Polymyalgia rheumatica

Widespread pain | Focal areas produced by 4kg digital pressure in 11/18 typical locations over muscles, tendon and bones (p. 1461)

Fibromyalgia

Deposition of bone within substance of muscle (p. 1463)

Myositis ossificans

First symptom of myositis ossificans (p. 1463)

firm swelling and tenderness in a paracertebral or cervical muscle

Myositis ossificans vs calcinosis universalis (p. 1463)

Calcinosis universalis usually occurs in relation to scleroderma or polymyositis and is characterized by calcium deposits in the skin, SC tissues, and connective tissue sheaths round the muscles. In myositis ossificans, there is actual bone in the muscles.

Treatment for myositis ossificans (p. 1463)

Diphosphanate (inhibits deposition of calcium phosphate)