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Flashcards in Skeletal Muscle and PNS Deck (29):
1

Trichinosis

• Trichinella spiralis (nematode) from pigs/pork

• Dystrophic calcification in muscle

• Muscle pain, periorbital edema, splinter hemorrhages; possible myocarditis or encephalitis

2

Myotonic dystrophy

• Autosomal dominant

• Trinucleotide repeat disorder

• Facial muscle weakness, percussion and grip myotonia (can't relax muscles), cardiac conduction defects

• Frontal balding, testicular atrophy, glucose intolerance

• Increased serum CK

• Causes of death: muscle wasting, cardiac fxn defects

3

Amyotrophic lateral sclerosis

• Loss of upper and lower motor neurons (no sensory change)

• 40-60 yrs old

• Bad superoxide dismutase 1

• Begins as muscle wasting in one hand, fasciculations

• Spasticity, Babinski sign, muscle weakness, respiratory muscle paralysis

4

Acute intermittent porphyria

• Autosomal dominant

• Uroporphyrinogen synthase deficiency —> increased PBG and ALA

• Urine wine-red on exposure to light

• Increasing p450 (e.g. with alcohol) precipitates attacks

• Recurrent severe abd pain, peripheral neuropathy, psychosis, dementia

5

Vitamin B12 deficiency

• Posterior column and lateral corticospinal tract demyelination

• Dementia, peripheral neuropathy

6

Charcot-Marie-Tooth disease

• Autosomal dominant

• Peroneal nerve neuropathy

• Lower BLE muscle atrophy; "inverted bottle" appearance of legs

7

Guillain-Barré syndrome

• Autoimmune demyelination syndrome

• Common preceding infections: viruses, M. pneumoniae, Campylobacter jejuni

• Rapidly progressive ascending motor weakness starting in proximal muscles

• Depressed/absent DTRs

• Glove and stocking paresthesias

• Increased CSF proteins

8

Ulnar nerve injury (C8-T1)

• Medial epicondyle Fx

• "Claw hand"

9

Radial nerve injury (C5-T1)

• Midshaft humerus Fx or "Sunday morning palsy"

• Wrist drop

10

Axillary nerve injury (C5-6)

• Surgical neck of humerus Fx, anterior shoulder dislocation

• Can't abduct arm or hold horizontal position with downward force applied

11

Median nerve injury (C6-T1)

• Median nerve entrapment; RA, pregnancy, overuse

• Sensory abnormalities in 1st 3 fingers; may have "ape hand" with thenar atrophy

12

Common peroneal nerve injury (L4-S2)

• Lead poisoning, fibula neck Fx, cast tightness

• Loss of foot eversion/dorsiflexion, toe extension

• "Slapping gait" or "high-stepping gait"

• Plantar flexion with foot drop and inversion

• Loss of ankle jerk reflex

• Sensory deficits on anterolateral leg and dorsal foot

13

Erb-Duchenne palsy

• Brachial plexus lesion at C5-6

• "Waiter's tip" deformity

14

Duchenne and Becker muscular dystrophies

• Progressive muscle degeneration, esp. in pelvic and shoulder girdles

• XLR

• Decreased dystrophin on muscle biopsy, very high CK

15

Central core disease

• Autosomal dominant

• Ambulatory but weaker than normal; decreased DTRs

• Predominance of type I fibers

• Risk for malignant hyperthermia triggered by some anesthetics

16

Rod myopathy

• Rod-like inclusions accumulate w/in sarcoplasm

• Hypotonia, delayed motor development, kyphoscoliosis, involvement of face/pharynx/neck

17

Central nuclear myopathy

• Skeletal muscles w/ centrally located nuclei

• Facial muscle involvement w/ ptosis

• Dynamin 2 gene

• Type I fiber predominance

 

18

Polymyosotis

• Patients >20 yrs

• CD8 T cell autoimmune

• Proximal muscle weakness, dysphagia, difficulty holding head up

19

Inclusion body myositis

• Patients >50 yrs

• CD8 T cells

• Beta-amyloid inclusions (Congo red)

• Proximal OR distal muscle weakness, dysphagia

20

Dermatomyositis

• Rash on upper eyelids, face, trunk

• CD4 and CD8 T cells, immune complexes

21

Glycogen storage diseases

• Pompe disease: acid maltase deficiency, hypotonia, death <2 yrs

• McArdle disease: myophosphorylase deficiency, muscle cramps w/ exercise

• Tarui disease: PFK deficiency, muscle cramps w/ exercise

22

Lipid myopathies

• Carnitine deficiency: lipids in sarcoplasm, proximal muscle weakness + atrophy

• Carnitine palmitoyltransferase deficiency: muscle pain after exercise or fasting

23

Mitochondrial disease

• Accumulation of mitochondria —> ragged red fibers

• Cytochrome oxidase deficiency

24

Spinal muscular atrophy

• Autosomal recessive denervation disease

• Infantile (Werdnig-Hoffman): fatal w/in 1 yr, loss-of-fxn in apoptosis inhibitor gene

• Juvenile (Kugelberger-Welander): limb-girdle dystrophy; not necessarily progressive

25

Morton neuroma

• Swelling of plantar interdigital nerve b/w 2nd, 3rd, or 4th metatarsals 

• Repeated nerve compression from wearing high heels

26

Spinal and peripheral schwannomas

• Often from dorsal (sensory) spinal roots with radicular pain and SC compression

• Peripheral schwannomas: head, neck, extremities

• Firm and tan/gray w/ hemorrhae, necrosis, xanthomatous change, cystic degeneration; may have Verocay bodies

27

Encephalomyoneuritis

• Paraneoplastic syndrome 

• Sensory changes, gait change, confusion, weakness

• Small-cell lung cancer w/ anti-Hu Abs

28

Opsonus-myoclonus

• Children: neuroblastoma

• Adults: 10% of CA, often Hodgkin lymphoma

29

Eaton-Lambert syndrome (myasthenic-myopathic syndrome)

• Paraneoplastic syndrome often associated w/ small-cell lung CA

• Defect in Ach release from IgG targeting