Please enable JavaScript.
Coggle requires JavaScript to display documents.
Diseases of Skeletal Muscle & Peripheral Nerves (Muscular Myopathies…
Diseases of Skeletal
Muscle & Peripheral Nerves
Denervation Atropy
loss of LMNs
chemical release for surrounding neurons to connect to leftover muscle fibers
fiber type grouping pattern
A.
Loss of Motor Neuron Diseases
:
-
Amyotrophic Lateral Sclerosis
- neurons die, progressive, untreatable, fatal
-
Spinal Muscular Atrophy
: survival motor neuron mutation (
SMN gene
) > atrophic fasicles w/o reinnervation (SMA1 = most common, floppy baby; SMA2&3 = present later)
-
Peripheral Nervous System AXONAL Injury
- compression, infl, etc > 1. angular atrophy 2. fiber type grouping 3. target fibers (bullseye)
B. NMJ disorders - MG, LES
Muscular
Myopathies
Metabolic
Glycogen Storage Diseases:
accumulation in liver and skeletal muscle
a.
Pompe
(type II) - lysosomal storage (a1,4 glucosidase)
b. Forbes/Cori (type III) - debranching enzyme
c.
McArdle
- no myophorylase - myofiber necrosis, exercise cramps & rhabdo
Lipid Metabolism
- carnitine or carnitine palmitoyltransferase deficiency (lipid droplets in myofibrils)
Mitochondrial
- maternal inherirtance, lactica acidosis,
ragged-red fibers
(irregular trichrome stains of mito)
Congenital
floppy babies, early onset, joint contractures
central core disease - ryanodine receptor
mutation -
malignant hyperthermia
w certain inhaled anesthetics
Nemaline Rod Myopathy
- accumulation of Z-band material
Centronuclear/myotubular - central nuclei d/t mutations of myotylarin
Ion Channel
present as myotonia, hypotonic paralysis w
tubular aggregates on ECM
HypOkalemic Periodic Paralysis
- abdnormal VGCCs
HypERkalemic Periodic Paralysis
- abnormal Na+ channels
Inflammatory
Dermatomyositis
- infl around perimysium
Polymyositis
- CD8+ against endomysium >
lymphocytic myofibril infl
Inclusion Body
- finger flexors & quads - rimmed vacuoles
Muscular Dystrophies
Duchene's (Xp21), no dystrophin to anchor cytoplasm to ECM - no dystrophin seen when membrane stained
Becker's
Limb-Girdle - defects in dystrophin associated protein complex
Myotonic -
CTG
repeat in
DMPK gene
> type I fiber atrophy; numerous internalized nuclei,
ring fibers
Disorders of Peripheral Nerve
Inflammatory Neuropathies
Guillain-Barre Syndrome
- acute, demyelinating, ascending paralysis, recent "flu" (
camplobacter jejuni
); infiltration of nerves and roots by lymphocytes and macros > demyelination (axon untouched) (slowed conduction)
-
ascending paraysis, bilateral facial weakness, no reflexes, loss of vib/propio
Chronic Infl Demyelinating Polyradiculoneuropathy
-
onion bulbs
on ECM d/t demy/remy
Infectios Polyneuropathy
: leprosy, diptheria, HIV, etc
Hereditary
:
Charcot-Marie-Tooth
(HMSN I) - peroneal atrophy w
pes vacus
(high arch), nerves
hyperT & palpable
, onion bulbs, d/t abnormal peripheral myelin protein
HMSN II: axonal form - axons lost, minimal demy
HMSN III: Dejerine-Sottas Syndrome - U & L ext & trunk, axonal loss with onion bulb, myelin genes fucked up
Acquired
Neuropathies
Diabetic - 50% DM patients, distal, symetric, sensory, motor, ANS > loss of my & unmy axons w thickening of endomesial blood vesses
Traumatic
: extrinsic damage -
Wallerian degeneration
(axonal loss w myelin fragments)
Toxic - lead, aresenic
Malignancy - d/t compression, Abs, etx
Peripheral
Nerve Tumors
Schwanoma
- schwann cells only, commonly at cerebropontine angle (acoustic)
a.
Verocay bodies
- linear arrays
b.
Antoni
- hypercellular (A) next to hypocellular areas
c. benign aside from symptoms caused by compression, etc (
no malignent degernation
)
Neurofibroma
- many cell types, multiple tumors >
neurofibromatosis
;
malignent degernartion
(>cancer)