Chapter 21 - Peripheral Nerves And Muscles Flashcards

0
Q

What is the function of the neuromusculoskeletal system?

A

Sensory & motor (CNS)

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1
Q

What makes up the neuromusculoskeletal system?

A

PNS, muscles, osseous tissue

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2
Q

What makes up the motor unit?

A

Lower motor neuron/peripheral axon, neuromuscular junction, innervated myocytes

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3
Q

What is the parenchyma of the PNS?

A

Neuron

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4
Q

What makes the myelin in the PNS?

A

Schwann cells

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5
Q

Pathology of any portion of a motor unit leads to what dysfunction?

A

Painless weakness (myasthenia)

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6
Q

What kind of peripheral neuropathy involves direct injury to the axon and degeneration of peripheral segments?

A

Axonal neuropathy

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7
Q

What is the secondary loss of myelin called with axonal neuropathy?

A

Wallerian degeneration

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8
Q

After repair of axonal neuropathy, how is the axon different from before?

A

Decreased axon density and overall amplitude is decreased, as well

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9
Q

What kind of peripheral nerve injury involves damage to Schwann cells or myelin?

A

Demyelinating neuropathy

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10
Q

What is the pattern of destruction for demyelinating neuropathy?

A

Random internode demyelination (segmental demyelination)

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11
Q

How is the myelin different after repair of demyelinating neuropathy?

A

Thinner myelin and shorter internodes leading to slowed nerve conduction velocity (NCV)

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12
Q

A shoulder dislocation can lead to which mononeuropathy?

A

Axillary nerve palsy

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13
Q

Carpal tunnel syndrome can lead to which mononeuropathy?

A

Thenar atrophy

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14
Q

What two things can cause mononeuropathies?

A

Entrapment or trauma

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15
Q

Diabetes and alcoholism can lead to what kind of peripheral nerve injury?

A

Polyneuropathy

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16
Q

Which axons are more at risk to be affected by polyneuropathies?

A

Distal segments of long axons

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17
Q

Stocking and glove paresthesia is seen among what kind of peripheral nerve injury?

A

Polyneuropathies

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18
Q

What kind of peripheral nerve injury damages random portions of individual nerves?

A

Polyneuritis multiplex

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19
Q

What type of peripheral nerve injury is common among autoimmune diseases?

A

Polyneuritis multiplex

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20
Q

What are various categories of causes of peripheral nerve injury?

A

Nutritional, toxic, vascular, inflammatory, genetic

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21
Q

What is the effect of Guillain-Barré syndrome on the nervous system?

A

Acute motor neuron demyelination

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22
Q

What is unique about the paralysis of Guillain-Barré syndrome?

A

Ascending paralysis leading to “rubbery legs”

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23
Q

How can Guillain-Barré syndrome be lethal?

A

Respiratory failure

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24
Q

What reflex is decreased with Guillain-Barré syndrome?

A

Deep tendon reflexes

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25
Q

Why is Guillain-Barré syndrome considered an auto immune disease?

A

Macrophages are seen near the nerve roots

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26
Q

What is the cause of Guillain-Barré syndrome?

A

60% the cause is unknown, but the remaining 40% are due to viruses such as C. jejuni, EBV, CMV, HIV (most of these except for HIV are minor viruses)

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27
Q

What is unique about the age range likelihood for diagnoses of Guillain-Barré syndrome?

A

Biphasic distribution (males ages 15-35 and 50-57)

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28
Q

What percentage of Guillain-Barré syndrome cases self-resolve?

A

90%

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29
Q

What is the treatment for Guillain-Barré syndrome?

A

Ventilation, plasmapheresis, IV antibodies

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30
Q

What is CIDP?

A

Chronic inflammatory demyelinating polyneuropathy

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31
Q

What is essentially the chronic and relapsing version of Guillain-Barré syndrome?

A

Chronic inflammatory demyelinating polyneuropathy (CIDP)

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32
Q

What genetic cause of peripheral nerve injury involves symmetric segmental demyelination giving off the appearance of “onion-skin” Schwann cells?

A

Chronic inflammatory demyelinating polyneuropathy

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33
Q

What gender is most like to get GBS or CIDP?

A

Males

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34
Q

What is the most common age range for CIDP?

A

40-60

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35
Q

CIDP is associated with which immune disorders?

A

Lupus, HIV

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36
Q

What is the treatment for chronic inflammatory demyelinating polyneuropathy?

A

Plasmapheresis, immunosuppression

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37
Q

What are symptoms for CIDP?

A

Pain, paresthesia, ataxia, decreased deep tendon reflexes

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38
Q

What would one be more likely to recover from: GBS or CIDP?

A

GBS

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39
Q

What is common in recovery of chronic inflammatory demyelinating polyneuropathy?

A

Loss of function (unable to get it back unlike GBS)

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40
Q

What is the #1 cause of peripheral neuropathy?

A

Diabetic peripheral neuropathy

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41
Q

Diabetic peripheral neuropathy is seen among what percentage of diabetes mellitus patients?

A

50%

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42
Q

What is the pattern of symptoms for diabetic peripheral neuropathy?

A

Symmetric

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43
Q

Vascular tissue injury as a result from hyperglycemia ultimately leading to nerve damage is associated with what cause of peripheral nerve injury?

A

Diabetic peripheral neuropathy

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44
Q

What is the name of the blood vessels that are damaged in diabetic peripheral neuropathy?

A

Vasa nervorum

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45
Q

What are the symptoms of diabetic peripheral neuropathy?

A

Decreased deep tendon reflexes along with decreased sensation of vibrations, soft touch, and pain

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46
Q

What is the treatment for diabetic peripheral neuropathy?

A

Blood glucose monitoring, daily inspection (analgesics and anticonvulsants)

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47
Q

What two possible signs of diabetic peripheral neuropathy are constantly checked for during daily inspections?

A

Gangrene and ulcers

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48
Q

How do environmental toxins lead to peripheral nerve injury?

A

Alter axonal transport or cytoskeleton damage of the longest neurons

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49
Q

ADRs, lead, and methyl-mercury are examples of what kind of cause of peripheral nerve injury?

A

Environmental toxins

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50
Q

What is the frequency of vasculitis patients have polyarteritis nodosa?

A

1/3

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51
Q

What is the genetic cause of periphery nerve injury?

A

Charcot-Marie-Tooth disease

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52
Q

What is the genetic mutation involved with Charcot-Marie-Tooth disease?

A

PMP22 gene

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53
Q

Charcot-Marie-Tooth disease is most common amount what population?

A

Young adults

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54
Q

What is the primary example of an inherited cause of peripheral neuropathy?

A

Charcot-Marie-Tooth disease

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55
Q

Extreme pes cavus is seen with what cause of peripheral nerve injury?

A

Charcot-Marie-Tooth disease

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56
Q

What is the pathway for myofiber depolarization?

A

Pre synaptic calcium influx —> acetylcholine release —> post synaptic ACh receptor

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57
Q

What neuromuscular junction disorder involves the degradation of post synaptic ACh receptors disabling the neuronal impulse?

A

Myasthenia gravis

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58
Q

What is the frequency of myasthenia gravis?

A

3:100,000 (not common)

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59
Q

What effects of the thymus can be see with myasthenia gravis?

A

Hyperplasia (60%) or a benign thymoma (20%)

60
Q

What is the result of thymic lesions from myasthenia gravis on the individual cells?

A

Autoreactive T cells and B cells

61
Q

What is the hallmark sign for myasthenia gravis?

A

Extraocular weakness, diplopia, and ptosis

62
Q

What gender is more likely to be affected by myasthenia gravis?

A

Females (auto immune condition)

63
Q

What is the typical age range for females acquiring myasthenia gravis?

A

20-30

64
Q

What is the typical age range for males acquiring myasthenia gravis?

A

50-70

65
Q

What effect does e-stimulation have on those with myasthenia gravis?

A

Worsened condition

66
Q

What is the survival rate of those with myasthenia gravis?

A

95% 5 year survival

67
Q

What neuromuscular junction disorder involves the degradation of pre synaptic calcium channels disabling the neuronal impulse?

A

Lambert-Eaton syndrome (LES)

68
Q

What effect does e-stimulation have on Lambert-Eaton syndrome?

A

Improves condition

69
Q

What is the frequency of Lambert-Eaton syndrome?

A

Extremely rare, 5:1 million

70
Q

What gender is more likely to have Lambert-Eaton syndrome?

A

Females

71
Q

What is the usual age range for Lambert-Eaton syndrome?

A

60 years of age

72
Q

Paraneoplastic syndrome or small cell lung cancer is associated with which neuromuscular junction disorder?

A

Lambert-Eaton syndrome

73
Q

What condition involves increased acetylcholine released to contract the muscles consistently leading to neuromuscular junction disorders?

A

Tetanus (Clostridium tetani)

74
Q

How do clostridium tetani and botulinum spread to cause infection and release neurotoxins?

A

Through soil

75
Q

What condition involves decreased acetylcholine release resulting in descending paralysis?

A

Botulism (clostridium botulinum)

76
Q

Does a peripheral axon innervate just one or multiple myocytes?

A

Multiple (in a checkerboard pattern)

77
Q

Which muscle fiber type involves slow twitch movement?

A

Type I

78
Q

Which muscle fiber type involves dark tissue?

A

Type I

79
Q

Which muscle fiber type is associated with fat metabolism and being aerobic?

A

Type I

80
Q

Why do type I muscle fibers appear dark?

A

Excess myoglobin

81
Q

Which muscle fiber type is associated with fast twitch movement?

A

Type II

82
Q

Which muscle fiber type appears white?

A

Type II

83
Q

What muscle fiber type is associated with glycogen metabolism and being anaerobic?

A

Type II

84
Q

What determines myofiber type?

A

Peripheral axons

85
Q

What is the definition of myopathy?

A

Disease of muscular origin, weakness

86
Q

What effect do neuropathic changes have on motor units?

A

They become fewer in number and larger in size

87
Q

Disuse atrophy primarily affects what type of muscle fibers?

A

Type II

88
Q

Glucocorticoid atrophy primarily affects which type of myofiber?

A

Type II

89
Q

What is the most common way to develop glucocorticoid atrophy?

A

Exogenously (endogenously would occur due to something like a pituitary tumor in Cushing’s disease)

90
Q

Static hypotonia is a characteristic of what kind of inherited disorder of skeletal muscle?

A

Congenital myopathies

91
Q

Is muscular dystrophy congenital?

A

No, rarely

92
Q

Which disorder of skeletal muscle is progressive in nature, inherited, but not congenital?

A

Muscular dystrophy

93
Q

What is the most common cause of muscular dystrophy?

A

Dystrophinopathies (dystrophin gene mutation on the X chromosome)

94
Q

What gender is more likely to be affected by muscular dystrophy?

A

Males (X-linked)

95
Q

What occurs with muscular dystrophy?

A

Myocyte degeneration outpaces repair

96
Q

What are the two types of muscular dystrophy?

A

Duchenne and Becker

97
Q

Which type of muscular dystrophy is associated with the complete absence of dystrophin?

A

Duchenne

98
Q

Which type of muscular dystrophy is more severe?

A

Duchenne

99
Q

What is the age and pattern of progression of Duchenne muscular dystrophy?

A

Weakness by age 5, wheelchair by teens, fatal by young adulthood

100
Q

Which type of muscular dystrophy involves abnormal dystrophin and variable severity?

A

Becker

101
Q

Which is more common: Duchenne of Becker muscular dystrophy?

A

Duchenne

102
Q

Which type of muscular dystrophy has an adolescent onset and usually a normal life span?

A

Becker

103
Q

What is the frequency of Duchenne muscular dystrophy?

A

1:3,500

104
Q

What specific areas exhibit extreme weakness in those with dystrophinopathies?

A

Pelvic girdle (also possible shoulder girdle weakness in advanced stages)

105
Q

What effect can be see in the calf muscles of those with dystrophinopathies?

A

Pseudohypertrophy involving fibro-fatty infiltrate buildup

106
Q

Elevation of what substance seen in a blood test can indicate dystrophinopathies?

A

Creatine kinase (indicates muscle breakdown)

107
Q

How do those with dystrophinopathies usually die?

A

Cardiorespiratory insuffiency (specifically cardiomyopathy, arrhythmia, pneumonia

108
Q

Gower’s sign is associated with what condition?

A

Muscular dystrophy

109
Q

What is Gower’s sign?

A

Using hands to push on legs “crawling up” on oneself in order to stand

110
Q

In polymyositis, T cells attack what structure to induce inflammation?

A

Endomysium

111
Q

What gender and age range are likely to develop polymyositis?

A

Males age 45-60

112
Q

What is the most common inflammatory myopathy in children?

A

Dermatomyositis

113
Q

Which inflammatory myopathy is also considered a paraneoplastic syndrome in adults?

A

Dermatomyositis

114
Q

What inflammatory myopathy involves tau proteins in the cytoplasm, progressive weakness, wasting, and dysphagia that may lead to degeneration?

A

Inclusion body myositis

115
Q

What is the most common inflammatory myopathy in the elderly (>60)?

A

Inclusion body myositis

116
Q

Which toxic myopathy involves the overproduction of thyroxine (thyrotoxicosis)?

A

Thyrotoxic myopathy

117
Q

Goiter and Graves’ disease are what kind of myopathy?

A

Thyrotoxic myopathy

118
Q

Rhabdomyolysis is associated with what toxic myopathy?

A

Ethanol myopathy

119
Q

Binge drinking can result in what toxic myopathy?

A

Ethanol myopathy

120
Q

Why can ethanol myopathy be lethal?

A

Can lead to renal failure

121
Q

What is the most common cause of drug myopathy?

A

Statins

122
Q

What are statins used for?

A

Cholesterol reduction

123
Q

Peripheral nerve sheath tumors are most common among what age group?

A

Adults

124
Q

What is the issue associated with a benign peripheral nerve sheath tumor?

A

Impingement can lead to pain and loss of function

125
Q

Are Schwannomas usually benign or malignant?

A

Benign

126
Q

What cranial nerve is most commonly involved with a Schwannoma?

A

VIII (vestibular Schwannoma)

127
Q

Which type of peripheral nerve sheath tumor is 90% sporadic?

A

Schwannoma

128
Q

Which type of peripheral nerve sheath tumor involves a genetic predisposition?

A

Schwannomatosis

129
Q

What is Schwannomatosis?

A

Multiple CNS and cutaneous Schwannomas

130
Q

Is cranial nerve VIII also usually affected by Schwannomatosis?

A

No, usually avoided

131
Q

What is a neurofibroma?

A

Benign and cutaneous nerve sheath tumor

132
Q

When can neurofibromas become a greater issue?

A

When involved in a plexiform area like the brachial or sacral plexus

133
Q

What condition involves bilateral vestibular Schwannomas?

A

Neurofibromatosis type 2 (NF2)

134
Q

What is the genetic pattern of neurofibromatosis type 2?

A

Autosomal dominant, Merlin gene involved

135
Q

What types of issues are seen with those with neurofibromatosis type 2?

A

Vision and hearing difficulties (no cutaneous lesions)

136
Q

What condition involves pronounced neurofibromas and vascular stenosis?

A

Neurofibromatosis type 1

137
Q

What are some effects of neurofibromatosis type 1?

A

Decreased condition and seizures

138
Q

What is the genetic pattern of neurofibromatosis type 1?

A

Autosomal dominant, mutation on chromosome 17

139
Q

What sign on the iris is associated with neurofibromatosis type 1?

A

Lisch nodules

140
Q

Axillary freckling, multiple neurofibromas, and cafe au lait spots are associated with what peripheral nerve sheath tumor condition?

A

Neurofibromatosis 1

141
Q

What is the most common location for malignant peripheral nerve sheath tumors?

A

Plexiform

142
Q

Malignant nerve sheath tumors are the result of the transformation of what previous condition?

A

Neurofibroma

143
Q

50% of all malignant peripheral nerve sheath tumors arise in patients with what condition?

A

Neurofibromatosis type 1

144
Q

What percentage of all neurofibromatosis type 1 patients will go on to develop malignant peripheral nerve sheath tumors?

A

3-10%

145
Q

What is the common location for traumatic neuroma?

A

Metacarpals and metatarsals

146
Q

Are traumatic neuromas malignant?

A

No, benign

147
Q

What makes up a traumatic neuroma?

A

Schwann cells, axons, and connective tissue