Skeletal Muscle & PNS pathology

Question 1

What indicates denervatoin with renervation?

Answer 1

grouping of muscle fibers

Question 2

When does muscle hypertrophy occur?

Answer 2

secondary to increased load due to exercise or pathologic conditions

Question 3

What does muscle degeneration/necrosis cause?

Answer 3

destruction of all or part of a myofiber, stimulates infiltration by macrophages

Question 4

How does regeneration of muscle occur?

Answer 4

satellite cells around degenerated fiber proliferate, regenerating fiber has blueish color & enlarged nuclei

Question 5

What does hypertrophied muscle look like on biopsy?

Answer 5

rounder/less polygonal

Question 6

What changes occur due to denervation atrophy?

Answer 6

clusters of fibers of one type become smaller and develop angular contours (group atrophy)

Question 7

What does lack of neural input result in on the cellular level?

Answer 7

breakdown of myosin and actin
resorption of myofibrils
decrease in cell size

Question 8

How does fiber type grouping occur?

Answer 8

with reinnervation neighboring axons sprout and reinnervate denervated myocytes, fiber assumes the fiber type conferred by the neighboring axonW

Question 9

What are the major differences between neurogenic and myopathis path?

Answer 9

neurogenic: bimodal size dist, angulated fibers, apparent increase in nuclei, no necrosis
myopathic: random size variation, round fibers, centralization of nuclei, necrosis

Question 10

Is ALS an UMN or LMN problem?

Answer 10

both!!

Question 11

Why does weakness occur in ALS?

Answer 11

loss of alpha motor neurons

Question 12

What are signs/sx of ALS?

Answer 12

flail arm
dysphagia/dysarthria/tongue atrophy
fasciulations
hyperreflexia
positive babinski
spasticity
pseudobulbar palsy
executive dysfunction

Question 13

Is SMA an UMN or LMN problem?

Answer 13

LMN

Question 14

How is SMA inherited?

Answer 14

Autosomal recessive

Question 15

What gene is deleted in SMA?

Answer 15

SMN1 (survival motor neuron) gene

Question 16

Where is there the most muscle weakness in SMA?

Answer 16

proximal muscles

Question 17

What leads to death in SMA?

Answer 17

respiratory weakness/hypercapnea

diaphragm fails, intercostal weakness

Question 18

What is seen on biopsy in SMA?

Answer 18

large groups of rounded atrophic fibers and sparse, scattered, markedly hypertrophic fibers

Question 19

What is the difference between Duchenne & becker muscular dystrophy?

Answer 19

duchene’s–>none/nearly no dystrohpin

becker’s–>abnormal dystrophin in reduced quantity (or normal dystrophin in reduced quantity)

Question 20

What gene is mutated in duchenne/becker MD?

Answer 20

Xp21

Question 21

What are signs/sx of duchenne’s MD?

Answer 21

proximal muscle weakness
slower movement than peers
large calves
gower's maneuver
face/eyes spared

Question 22

What CK value would you expect to find in DMD?

Answer 22

> 10,000

Question 23

What are signs/sx of becker’s MD?

Answer 23

late onset

similar to duchenne’s

Question 24

What is the genetic problem in myotonic dystrophy?

Answer 24

CTG repeat expression in DMK gene on chr 19

DM1 dystrophia myotonica type 1

Question 25

Who gets myotonic dystrophy?

Answer 25

adults

Question 26

How is myotonic dystrophy inherited?

Answer 26

autosomal dominant

Question 27

What are signs/sx of myotonic dystrophy?

Answer 27

difficulty releasing grip--->myotonia foot drop temporal wasting/elongated face endocrine abnormalities (test atrophy, balding, Diabetes) premature cataracts cardiac arrhythmias the higher the repeat number the lower the intelligence

Question 28

What characteristic sound is heard on EMG of a myotonic dystrophy patient?

Answer 28

divebomber

Question 29

What does myotonic dystrophy have in common with huntington's disease?

Answer 29

genetic anticipation

Question 30

What does MELAS stand for?

Answer 30

``` mitochondrial myopathy encephalopathy lactic acidosis stroke-like episodes ```

Question 31

What causes melas?

Answer 31

MtDNA mutation

Question 32

What is a myopathic form of a glycogen storage disease? What causes it?

Answer 32

V-McArdle's disease | phosphorylase deficiency

Question 33

What are the clinic sx of V-McArdle's disease?

Answer 33

exercise intolerance with cramps and intermittent myoglobinuria

Question 34

What is a generalized form of a glycogen storage disease? What causes it?

Answer 34

Pompe's disaese | acid maltase deficiency

Question 35

What do you see microscopically with pompe's disease?

Answer 35

vacuoles

Question 36

What are the 3 inflamatory myopathies?

Answer 36

inclusion body myositis dermatomyositis polymyositis

Question 37

What are the clinical findings of polymyositis?

Answer 37

symmetric proximal muscle weakness no rash F>M assoc w/other autoimmune diseses

Question 38

What cell type is dominent in the inflammation of polyomyositis?

Answer 38

CD8 T cells (endomysial infiltrattes)

Question 39

What is the pathology of dermatomyositis?

Answer 39

Microvasculature is attacked by antibodies and complement B cells predominate Ischemic atrophy and necrosis (perifascicular atrophy)

Question 40

What are signs/sx of dermatomyositis?

Answer 40

``` shawl sign heliotrope (violaceous) rash around eyes nail bed with thrombi and hemorrhages gottron's papules subcutaneous calcifications proximal weakness ```

Question 41

What is sign microscopically with dermatomyositis?

Answer 41

chronic inflammation perifascicular atrophy perivascular, perimysial and endomysial infiltrates

Question 42

Which inflammatory myopathies respond to immunosuppression?

Answer 42

Dermatomyositis and polymyositis

Question 43

What conditions are associated with polymyositis?

Answer 43

SLE PAN scleroderma

Question 44

What conditions are associated with dermatomyositis?

Answer 44

myocarditis interstitial lung disease malignancy vasculitis

Question 45

What are group is affected most my dermatomyositis?

Answer 45

children & adults

Question 46

Is there a rash associated with IBM?

Answer 46

no

Question 47

What is seen microscopically with IBM?

Answer 47

``` endomysial infiltrates (CD8) rimmed vacuoles amyloid depositis invasion of non-necrotic fibers tubulofilamentous inclusions ```

Question 48

What is the pattern of weakness in IBM?

Answer 48

proximal=distal deep finger flexors quads dysphagia

Question 49

Describe steroid induced myopathy?

Answer 49

proximal weakness high dose, prolonged steroid use type 2b atrophy

Question 50

What type of myopathy is induced by statins?

Answer 50

necrotizing immune mediated

Question 51

What is neuronopathy/axonopathy?

Answer 51

generalized abnormality affecting neuronal cell body and or axon

Question 52

What is wallerian degeneration?

Answer 52

focal lesion causing axonal injury | portion of fiber (axon and myelin) distal to focal injury degenerates (ie transection)

Question 53

What is another name for acute inflammatoroy demyelinating polyradiculoneuropathy?

Answer 53

guillain barre syndrome

Question 54

What are the symptoms of AIDP?

Answer 54

``` rapidly ascending weakness respiratory weakness bulbar weakness autonomic-cardiac rhythm preceeding viral illness areflexia ```

Question 55

What is seen in the CSF of AIDP & CIDP patients?

Answer 55

high protein, normal cells, cytoalbuminologic dissociation

Question 56

What do both AIDP and CIDP show on EMG/NCS?

Answer 56

demyelinating features

Question 57

What are the symptoms of CIDP?

Answer 57

slowly progressive weakness, moving from proximal to distal | no preceeding illness

Question 58

Is AIDP or CIDP monophasic?

Answer 58

AIDP

Question 59

How is AIDP treated?

Answer 59

IVIG | PLEX

Question 60

How is CIDP treated?

Answer 60

Prednisone IVIG PLEX

Question 61

Describe mononeuritis multiplex/vasculitis?

Answer 61

peripheral nerves are infarcted leading to foot drop and hand weakness

Question 62

What is seen on biopsy for mononeuritis multiplex?

Answer 62

inflammation of nerve | vascular necrosis

Question 63

What causes leprosy?

Answer 63

mycobacterium leprae

Question 64

What form of leprosy develops if patient mounts a T cell response?

Answer 64

tuberculoid

Question 65

What happens when mycobacterium leprae invade the nerves and skin?

Answer 65

they cause inflammation and caseating granulomas

Question 66

What is herpes zoster?

Answer 66

a VZV reactivation

Question 67

Where does VZV remain dormant?

Answer 67

satellite cells, DRG

Question 68

How is pain distributed in herpes zoster?

Answer 68

dermatomal distribution

Question 69

What is an example of a hereditary neuropathy?

Answer 69

charcot marie tooth type 1A

Question 70

What mutation causes CMT1A?

Answer 70

PMP22 mutation, Autosomal dominant

Question 71

What are the signs/sympomts of CMT1A?

Answer 71

``` onset early teens demyelinating disease foot drop "inverted champagne bottle/stork legs" tripping, falling, clumsy walk claw hands ataxia, loss of proprioception pes cavus, hammer toes ```

Question 72

What is the key histologic finding for CMT1A?

Answer 72

onion bulbs

Question 73

How does diabetic neuropathy present?

Answer 73

stocking/glove distribution OR diabetic amyotrophy (lumbosacral plexus lesion -> quad atrophy) Both: painful, tingling, numbness, foot drop, proprioceptive loss

Question 74

What nerve is impinged in carpal tunnel syndrome?

Answer 74

median

Question 75

What is a Morton's neuroma/traumatic neuroma?

Answer 75

intraneural scarring | caused by fracture, compression or surgical lesion of nerve

Question 76

what are the symptoms of morton's neuroma?

Answer 76

persisten, incapacitating pain & tingling at site of injury