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System Pathology I -- Roecker > Exam 2: PNS Pt1 > Flashcards

Exam 2: PNS Pt1 Flashcards

1
Q

What are the two primary patterns of peripheral nerve injury?

A
  1. Axonal Neuropathy

2. Demyelinating Neuropathy

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2
Q

What describes the fragmentation of the axon and myeling that occurs distal to the area of the injured axon?

A

Wallerian degeneration

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3
Q

What does Axonal neuropathy manifest like?

A

direct injury to peripheral axon involving degeneration of distal portion of axon and eventually myelin

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4
Q

What describes the discontinuous internode demyelination caused by demyelinating neuropathies?

A

segmental demyelination

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5
Q

Is repair of axonal neuropathy or demyelinating neuropathy possible? If so, what is the result?

A

Yes, but…
- decrease in axonal density and nerve condution velocity test (NCV)

  • thin myelin and shorted internodes and decrease in NCV
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6
Q

What describe damage to a individual peripheral nerve? How do they manifest?

A

Mononeuropathy; isolated motor or sensory defects

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7
Q

What are some examples of trauma that may result in mononeuropathy?

A
  • carpal tunnel syndrome

- follow inf. disease–Lyme Disease

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8
Q

What describes damage to multiple peripheral nerves? How does it manifest

A

polyneuropathy; symmetric sensory or motor defects; longest axons–therefore begin in distal extremities (“stalking-and-glove”)

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9
Q

What is paraesthesia?

A

abnormal “pins and needles” sensation that is frequently ass. with numbness or burning

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10
Q

What are some conditions that may cause Polyneuropathy?

A
  • advanced diabetes mellitus
  • toxic exposures (led toxicity, binge drinking alc)
  • vitamin deficiencies
  • autoimmmune conditions
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11
Q

What syndrome is a poorly-understood immune-condition causing acute demyelination primarily of motor neurons in lower extremities?

A

Guillian-Barre Syndrome (GBS)

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12
Q

How does Gullian-Barre Syndrome manifest?

A
  • acute onset of lower extremity weakness and lack of stability standing/walking
  • *ascending paralysis–> “rubbery legs”
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13
Q

Can Gullain-Barre Syndrome be lethal?

A

yes, if ascending paralysis reaches muscles of respiration (diaphragm)

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14
Q

What PNS disorder has a bimodal distribution that most likely occurs in individuals b/w 15-35 or 50-60 years?

A

Gullian Barre Syndrome

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15
Q

What is the recovery rate from Gullian Barre Syndrome?

A

~90% self-recover, but may be weeks to years

younger–full recovery
older– may experience Chronic Inflam. Demyelinating Polyneuropathy

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16
Q

What inflammatory env. exposure is known to stimulate the majority of the infection related cases of GBS?

A 
Campylobacter jejuni 
(~30% of all cases)

–still 60% idopathic

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17
Q

What is a chronic immune-mediated demyelinating disorder that causes sensory and motor neuropathies that persists for at least 2 months in duration?

A

Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)

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18
Q

What age and sex does CIDP(chronic inflammatory demyelinating polyneuropathy) MC affect? How common is CIDP?

A

2x-males; ages 40-60

1 in 20,000

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19
Q

What is a characteristic feature of Schwann cells involved in chronic inflammatory demyelinating polyneuropathy?

A

“onion bulb” appearance due to replapsing of demyelination and remyelination that occurs

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20
Q

What are some risk factors for developing chronic inflammatory demyelinating polyneuropathy (CIDP)?

A
  • various forms of “immune dyregulations” - - history of Lupus (SLE) or HIV
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21
Q

What are the symptoms that manifest with chronic inflammatory demyelinating polyneuropathy (CIDP)?

A

insidious onset of:

  • limb weakness
  • ataxia
  • loss of balance
  • paresthesia
  • fatigue
  • muscle pain/cramping
  • radiculopathy (nerve pain)
  • decrease deep tendon reflexes
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22
Q

What involves axonal and demyelinating nerve damage in patients with long-term diabetes mellitus?

A

Diabetic Neuropathy

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23
Q

What is the MC form of peripheral neuropathy?

A

Diabetic Neuropathy

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24
Q

Even though completely not understood, what does Diabetic neuropathy develop in part from?

A

oxidative injury to body’s microvasculature (vasa nervorum) following prolonged periods of hyperglycemia

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25
Q

What is Diabetes mellitus?

A

(DM or diabetes) = metabolic disorder characterized by prolonged levels of hyperglycemia

involves type I DM, type 2 DM, and gestational diabetes

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26
Q

What are the small arteries that supply blood and nutrients to peripheral neurons called?

A

vasa nervorum

injuried in Diabetic neuropathy

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27
Q

What is the most common way that Diabetic neuropathy manifests?

A

effects longest neurons

  • MC way = distal symmetric sensorimotor polyneuropathy
  • beings as paresthesia and follows “stalking-and-glove” pattern
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28
Q

T/F. When it comes to paresthesia of different pathologies, motor dysfunction comes before sensory dysfunction.

A

False– sensory before motor

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29
Q

What do the sensory abnormalities associated with Diabetic neuropathy put the individual at risk for?

A

undetected wounds that become infected and cause gangrenous necrosis (typically toes or feet)

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30
Q

What individuals are prone to ulcerations on the skin (feet) due to poor wound healing from microvascular injury?

A

inds with Diabetic Neuropathy

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31
Q

What is the term for when the ANS is injured due to long-term diabetes? What may this cause?

A

Autonomic Neuropathy

  • bowel, bladder, cardiac, or sexual dysfunction
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32
Q

What are four pathologies that Diabetic Neuropathy may cause?

A
  1. Autonomic Neuropathy
  2. Lumbosacral Radiculopathy
  3. Diabetic Retinopathy
  4. Diabetic Nephropathy
33
Q

What will lumbosacral radiculopathy (a potential result from diabetic neuropathy) manifest as?

A

asymmetric pain, weakness, or atrophy in lower extremities

34
Q

What pathology may result in blindness that could be caused by Diabetic neuropathy?

A

Diabetic Retinopathy

35
Q

Diabetic Neuropathy may cause Diabetic Nephropathy. What does that put the individual at risk for?

A

(glomerulonephritis)–> kidney failure

36
Q

What is characterized by progressive joint destruction, dislocations, and pathologic fxs following a neuropathy that reduced lower extremity joint sensation?

A

Neuropathic arthropathy (Charcot joint or neuropathic joint)

37
Q

Where is neuropathic arthropathy lost likely to occur?

A

in weight-bearing joints; like foot, ankle, or hip following unperceived trauma

38
Q

What is the most common cause of someone developing a Neuropathic joint (neuropathic arthropathy)?

What could be other causes?

A

Diabetic Neuropathy

spinal cord injury, syphilis, leprosy

39
Q

How does Neuropathic arthropathy manifest/ what are the symptoms?

A
  • severe swelling
  • permanent joint destruction
  • severe disability
40
Q

What are additional causes of Peripheral Nerve Injury?

A
  • drugs/ toxic env. exposures (lead)–> may interfere with cytoskeleton of peripheral neurons (affect longest axons to distal extremities)
  • Systemic Vasculitis
41
Q

How would Systemic Vasculitis cause peripheral nerve injury?

A

inflam. may extend to peripheral nerves and cause injury or induce ischemia

42
Q

How many people with Systemic Vasculitis have peripheral nerve injuries at time of their Dx?

A

~1/3

43
Q

What conditions characteristically cause systemic vasculitis?

A
  • systemic lupus erythematosus
  • polyarteritis nodosa
  • rheumatoid arthritis
44
Q

What represents a related group of inherited neuropathies that collectively affect about 1 in 2,500 individuals?

A

Charcot-Marie-Tooth Disease (CMT)

45
Q

When does Charcot-Marie-Tooth Disease (CMT) most likely onset? What does it commonly present with?

A

first two decades of life

progressively worsening lower extremity weakness and difficulty walking (ataxia)

46
Q

What inherited disease as it gets more severe has a noticeable foot drop and a “steppage gait” that develops, and may involve pes cavus development?

A

Charcot-Marie-Tooth Disease (CMT)

47
Q

What is pes cavus?

A

a high arched foot that does not flatten wen weight-bearing

48
Q

What form of CMT disease develops following an inherited PMP22 gene mutation?

A

(CMT 1); mutation results in formation of abnormal myelin and causes demyelination atrophy

49
Q

Disorders of the neuromuscular junction produce a wide variety of what kind of defects?

A

motor defects

50
Q

What are the three characteristic examples that we are focusing on that cause neuromuscular disorders?

A

autoimmune, paraneoplastic, or infectious origin

51
Q

What are the four neuromuscular junction disorders we are discussing?

A
  1. Myasthenia gravis
  2. Lambert-Eaton syndrome
  3. Tetanus
  4. Botulism
52
Q

What autoimmune condition involving antibodies against an inds own postsynaptic ACh receptors? What does this cause?

A

Myasthenia Gravis

inhibits myocyte depolarization and causes painless muscle weakness (myasthenia)

53
Q

What is Myasthenia Gravis a classic example of?

A

a Type II Hypersensitivity Reaction

54
Q

What makes the muscle weakness ass. with Myasthenia Gravis worse? Better?

A

Worse– muscle activation, physical activity, and electrical simtulation

Better–rest

55
Q

What is the most characteristic feature of Myasthenia Gravis? What are some other features?

A

unilateral or bilateral ptosis (eyelid drooping)

also axial and limb girdle weakness

56
Q

In Myasthenia Gravis, weakness of extraocular eye muscles may cause what? What if face or throat muscles are effected?

A

diplopia

dysphagia, dysarthria, difficulty chewing, or inhibited facial expressions

57
Q

What is considered a “myasthenic crisis”?

A

when muscle of respiration become affected in Myasthenia Gravis, and cause dyspnea

this is a medical emergency requiring mechanical ventilation for survival

58
Q

Most patients with Myasthenia Gravis experience enlargement of what gland?

A

thymus gland, due to:

  • thymic hyperplasia (60% cases)
  • thymoma (20% cases)

(B cells play a role)

59
Q

What individuals are most likely to get Myasthenia Gravis?

A

reproductive age females OR older adult males

~2 in every 100,000

60
Q

What procedure may reduce the severity of Myasthenia Gravis or even cure it?

A

thymectomy

61
Q

What autoimmune condition involves formation of anitbodies against one’s own presynaptic calcium ion channels? What does this cause?

A

Lambert-Eaton Syndrome (LES)

inhibits release of ACh in neuromuscular junction–> preventing myocyte depolarization –> causing myasthenia

62
Q

What characteristic of Lambert-Eaton syndrome (LES) mimics Myasthenia Gravis? What makes these disease different?

A

limb girdle muscle weakness

LES improves with repetitive electronic stimulation

63
Q

What does Lambert-Eaton Syndrome improve with repetitive electronic stimulation?

A

intracellular calcium ions build up to cause ACh release

64
Q

T/F. Lambert-Eaton Syndrome is fairly common.

A

False– it is rare, ~5 per 1,000,000

65
Q

40% of people with Lambert-Eaton Syndrome also have what?

A

Small Cell Lung Cancer

this 40% also represent the 3% of all patients with small celll lung cancer

66
Q

What is it considered when LES (Lambert-Eaton Syndrome) develops in patients with small cell lung cancer?

A

paraneoplastic syndrome

67
Q

What age is LES (Lambert-Eaton Syndrome) most likely to affect?

A

older adults; average age of Dx is ~ 60

68
Q

What are two infectious neuromuscular disorders we are focusing on?

A
  1. Tetanus

2. Botulism

69
Q

What is Tetanus characterized by?

A

muscle spasms following an infection with Clostridium tetani found in soil, dust, and manure as an endospore and thrives in anaerobic env.

70
Q

How does an inf. with Clostridium tetani create these muscle spasms ass. with tenanus?

A

it produces naturally-occuring neurotoxin that binds to peripheral nerve terminals and blocks release of inhibitory NTs (glycine and GABA)–> therefore increase in ACh activity

71
Q

Where are the MC places for muscle spasms ass. with tetanus?

A
  • jaw –> “lockjaw”

- neck, back, abdomen muscles

72
Q

What percentage of cases is tetanus lethal? why?

A

10% all cases; if affects muscles of respiration or cardiac musculature

73
Q

When tetanic spasms involve the spinal muscles, a state of severe hyperextension may occur, what is that called?

A

opisthotonus

74
Q

What is Botulism?

A

a condition characterized by muscle flaccidity following an infection with Clostridium botulism, present in bee honey or improperly canned foods

75
Q

Why is it recommended to not give babies/infants honey?

A

could cause botulism–> “infant botulism” or “floppy baby syndrome”

90% of all cases in US are in infants

76
Q

How does Clostrium botulism actually cause muscle flaccid paralysis?

A
  • survives in intestines and produces natural-occuring neurotoxin
  • inhibits release of ACh into neuromuscular jxn —> therefore causing muscle weakness/flaccidity
77
Q

What are other symptoms/manifestations of botulism besides muscle flaccidity?

A
  • blurred vision
  • bilateral ptosis
  • difficultiy speaking, chewing
  • dysphagia
78
Q

What peripheral neuropathy tends to develop superior-to-inferior, aka “descending paralysis”?

A

Botulism

79
Q

What percentage of cases of Botulism are lethal?

A

5% due to muscles of respiration becoming involved and causing dyspnea or lethal respiratory paralysis

System Pathology I -- Roecker (14 decks)

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