Skeletal Muscle / PNS Pathology Flashcards Preview

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Flashcards in Skeletal Muscle / PNS Pathology Deck (30)
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1
Q

What do degenerating vs regenerating neurons in the periphery look like?

A

Degeneration – Macrophages invading numerous nuclei surrouding the axons
Regeneration – Enlarged Nuclei and blue cytoplasm

2
Q

What is a unique chracteristic of re-innervation of muscle fibers?

A

–Grouping of similar type of fibers, contrary to mixed types throughout

3
Q

How can you tell neurogenic or myopathic muscle reactions?

A

Neurogenic – angulated fibers, nuclear clumps, NO Necrosis or inflammation
Myopathic – round fibers - central nuclei - NECROSIS
EMG can be used for testing

4
Q

What syndrome causes degradation of upper and lower motor neurons that progresses over time with emotion lability?

A

Amyotrophic Lateral Sclerosis

5
Q

What are the most common neurons affects in ALS?

A
  • -Motor Neurons

- - Anterior Horn – atrophy of nerve roots

6
Q

What is the most likely diagnosis of a 7 year old with trunkal/proximal muscle weakness, progressive dysphasia, and needing help to breath on respiratory due to the proximal weakness?

A

Spinal Muscular Atrophy

  • -Deletion of SMN1 (Survival Motor Neuron)
  • -Autosomal Recessive – two deletions required
7
Q

What is the protein that maintains integrity of muscle cells from physical stress and torsion?

A

– Dystrophin

if missing, then any action of the muscle can induce damage

8
Q

If a 9 year old male experiences progressive proximal muscle weakness, wide gait, difficulty with Gower’s maneuver, winged scapula, and elevated CK levels in serum?

A

Duchenne Muscular Dystrophy

    • Very minimal amount of Dystrophin present
    • Upregulated Utropin in muscles (to compensate)
9
Q

If a 64 year old male presents with years of progressive proximal weakness, what might be a likely diagnosis?

A

Becker Muscular Dystrophy

–Abnormal Dystropin and reduced quantity

10
Q

How are Duchenne and Becker muscular dystrophies similar?

A

Both are X-linked Recessive

11
Q

If there is a finding of expanded CTG repeats of the DMPK gene, what might be the disorder?

A

Myotonic Dystrophy

–Dysfunction of the

12
Q

What is the most common muscular dystrophy in adults?

A

Myotonic Dystrophy

  • -Autodominant
  • -Genetic Anticipation, more repeats pass on
13
Q

What are unique exam findings with Myotonic Dystropy?

A
  • Difficulty Releasing Grip – impaired Cl- conduction
  • Distal hands and feet weakness
  • Elongated face - temporal wasting
  • cardiac arrthymias
14
Q

How is Myotonic Dystrophy different from other dystrophies?

A

Myotonic – there is nothing wrong with Dystrophin

    • no destruction of muscle fibers
    • internal nucleation
15
Q

How do mitocondrial myopathies lead to disease?

A
  • -Due to inefficient production of ATP and then the cell is unable to function normally and oxidative damage also builds up, b/c no energy to combat them.
  • -Causes degradation of the cells
16
Q

What condition is associated with mitochondrial myopathy?

A

MELAS
Mito Myopathy, Encephalopathy, Lactic acidosis, stroke-like episodes
Why? – Not enough ATP being produced and cells become ischemic intermittently, thus reason for lactic acidosis

17
Q

What are the main clinical criteria for MELAS?

A

Stroke-like episodes, non-vascular in origin
Encephalopathy – neurodegenerative
Lactic Acidosis, ragged red fibers

18
Q

What are the most common types of glycogen storage diseases?

A

Myopathic Form – problem in muscles and exercise intolerance with cramps and myoglobinuria
Generalized Forms – Pompe’s Disease
–effects many organs, mostly heart - early death

19
Q

What would a main histologic finding be of various tissues with Pompe’s Disease?

A

Vacuoles filled with glycogen-products

- pools of glycogen

20
Q

Which inflammatory myopathy is associated with females, erythematous lesions over the knuckles and rash on the eyes?

A

Dermatomyositis

21
Q

What kind of immune response is responsible for Polymyositis?

A

CD8+ T cells – attacking muscle fibers

  • -Symmetric proximal muscle weakness
  • -associated with other auto immune diseases
22
Q

What is the underlying pathology for Dermatomyositis?

A

Microvascular being attacked by complement and antibodies
Muscle Biopsy: Perifascicular Atrophy in the muscle
(Since that part of the muscle fibers only have single blood supply, so they die, deeper have dual)

23
Q

If a 56 year old male is evaluated by muscle biopsy and found to have rimmed vacuoles and tubulofilamentous inclusions, what might be a clinical symptom?

A

Dysphasia

–Deep finger flexor atrophy and quad atrophy

24
Q

Which of the inflammatory myopathies can be found in children?

A

Dermatomyositis

25
Q

What might happen if a patient has prolonged use of high dose steroids?

A
  • -Proximal Muscle Weakness

- -Atrophy of Type 2B Fibers

26
Q

What are the two types of peripheral nerve pathologies?

A

Neuronopathy – Axon degenerating back proximally

Wallerian – focal lesion degenerates distally

27
Q

Where does Mononeuritis Multiplex usually affect?

A

Vasculitis
–Ulnar nerve – hand weakness
–Distal sciatic – foot drop
Dx – via nerve biopsy with inflammation

28
Q

What are the common manifestations of Leprosy?

A
  • Exposure to Mycobacterium leprae
  • Usually coming from another country previously in their life and get it years later (incubation)
  • Hypopigmented Lesions
  • Neuromas
29
Q

What pathology common has an “onion bulb” formation on histology?

A

Charcot Marie Tooth Type 1A

  • -gradual myelin loss
  • -autodominant PMP22 mutation/duplication
  • -usually affects the LONGEST nerves
30
Q

What kind of distribution is Diabetic Neuropathy?

A

–Sock and Glove numbness/tingling