Chapter 21: Peripheral Nervous System Flashcards
1
Q
What makes the myelin in the PNS?
A
Schwann Cells
2
Q
Pathology of any portion of a motor unit leads to what dysfunction?
A
Painless weakness (myasthenia)
3
Q
What kind of peripheral neuropathy involves direct injury to the axon and degeneration of peripheral segments?
A
Axonal Neuropathy
4
Q
What is the secondary loss of myelin called with axonal neuropathy?
A
Wallisian degeneration
5
Q
After repair of the axonal neuropathy, how is the axon different from before?
A
Decreased axon density and overall amplitude is decreased
6
Q
What kind of peripheral nerve injury involves damage to Schwann cells or myelin?
A
Demyelinating neuropathy
7
Q
What is the pattern of destruction for demyelinating neuropathy?
A
random internode demyelination (segmental demyelination)
8
Q
How is the myelin different after repair for demyelinating neuropathy?
A
Thinner myelin and shorter internodes leading to slowed nerve conduction velocity (NCV)
9
Q
A shoulder dislocation could caused what type of mononeuropathy?
A
Axillary nerve palsy
10
Q
An example of an entrapment mononeuropathy is?
A
carpal tunnel syndrome
11
Q
What are the two primary causes of mononeuropathies?
A
entrapment or trauma
12
Q
Diabetes and alcoholism can lead to what kind of peripheral nerve injury?
A
polyneuropathy
13
Q
What type of damage is common among polyneuropathies?
A
Diffuse/symmetric damage
14
Q
Polyneuropathy has what characteristic paresthesia present?
A
Stocking and glove paresthesia
15
Q
What is the effect of Guillain-Barre syndrome on the nervous system?
A
Acute motor neuron demyelination
16
Q
What is unique about the paralysis associated with Guillain- Barre syndrome?
A
Ascending paralysis which leads to “rubbery legs” and decreased deep tendon reflexes
17
Q
How can Guillain-Barre syndrome be lethal?
A
Respiratory failure
18
Q
Why is Guillain- Barre syndrome considered an auto immune disease?
A
Presence of macrophages near the nerve roots
19
Q
What is the cause of Guillain-Barre 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)
20
Q
What is the age range likelihood for diagnoses of Guillain-Barre syndrome?
A
Males ages 15-35 and 50-57
21
Q
90%of those affected by Guillain-Barre’ syndrome self-resolve
T or F
A
True
22
Q
What is the treatment for Guillain-Barre’ Syndrome?
A
Ventilation, plasmapheresis, IV antibodies
23
Q
What is another name for Chronic Guillain-Barre syndrome?
A
Chronic Inflammatory demyelinating polyneuropathy (CIPD)
24
Q
What genetic peripheral nerve injury involves symmetric segmental demyelination and gives off the appearance of “onion-skin” Schwann cells?
A
Chronic inflammatory demyelinating polyneuropathy
25
What signs are associated with Chronic Inflammatory Demyelinating Polyneuropathy?
Paresthesia/Pain, ataxia, and decreased deep tendon reflexes
26
What age and gender are most likely to contract Chronic Inflammatory Demyelinating Polyneuropathy?
Males, 40-60 years old
27
In class, what two risk factors were associated with CIDP?
SLE and HIV
28
What is the treatment for chronic inflammatory demyelinating polyneuropathy?
Plasm apheresis, immunosuppression
29
Which are you more likely to recover from: Guillain-Barre Syndrome or Chronic Inflammatory Demyelinating Polyneuropathy?
Guillain-Barre Syndrome because CIPD is commonly associated with permanent loss of function
30
What leads to the nerve injury present in Diabetic Peripheral Neuropathy?
Microangiopathy
31
Which blood vessels are damaged in Diabetic Peripheral Neuropathy?
vasa nervorum
32
True or False: The damage to the myelin and axons in Diabetic Peripheral Neuropathy is asymmetrical?
False; it is symmetrical
33
What are the symptoms of diabetic peripheral neuropathy?
Decreased deep tendon reflexes along with decreased sensation of vibrations, soft touch, and pain
34
What is the treatment for diabetic peripheral neuropathy?
Blood glucose monitoring, daily inspection (analgesics and anticonvulsants)
35
What two possible signs of diabetic peripheral neuropathy are constantly checked for during daily inspections?
Gangrene and ulcers
36
What is it called if a patient with Diabetic Peripheral Neuropathy has microanigopathy that occurs in the retina? What are the conditions that can occur?
Diabetic Retinopathy
Vision problems; possible blindness
37
What is it called if a patient with Diabetic Peripheral Neuropathy has microanigopathy that occurs in the kidneys? What are the conditions that can occur?
Diabetic Nephorpathy
Glomerulonephritis
38
What is a possible complication of any neuropathy?
Neuropathic Arthropathy
39
What is the cause of Neuropathic Arthropathy?
Decreased sensation which means patient has unperceived trauma or injury
40
What is the most common cause of Neuropathic Arthropathy?
Diabetes mellitus
41
What are three other causes of Neuropathic Arthropathy besides Diabetes Mellitus?
Spinal cord injury, syphilis, leprosy
42
What is the generic location for Neuropathic Arthropathies?
progressive degeneration in weight-bearing joints such as foot and ankle; to a lesser degree hips
43
How do environmental toxins lead to peripheral nerve injury?
Alter axonal transport or cytoskeleton damage of the longest neurons
44
ADRs, lead, and methyl-mercury are examples of what kind of cause of peripheral nerve injury?
Environmental toxins
45
Vasculitis is present in how many vasculitis patients?
1/3
46
Vasculitis is present in what three conditions?
polyarteritis nodosa, SLE, and RA
47
What is an example of Inherited Peripheral Nerve Injury?
Charcot-Marie-Tooth Disease
48
What is a group of similar conditions that lead to axonal or demyelinating neuropathy and is caused by a PMP22 mutation?
Charcot-Marie-Tooth Disease
49
What type of neurons are affected by Charcot-Marie-Tooth Disease
motor and sensory neurons
50
When is Charcot-Marie-Tooth disease most likely to be seen?
Young Adulthood
51
What are the types of severity that can be noticed in Charcot-Marie-Tooth disease?
Variable severity such as altered gait or debilitating gate
52
What muscles are affected by Charcot-Marie-Tooth Disease?
Muscles innervated by the common fibular nerve
53
What is the pathway for myofiber depolarization?
pre-synaptic Ca++ influx -> ACh release -> post-synaptic ACh receptor -> myofiber depolarization
54
Which neuromuscular junction disorder is an autoimmune attack against the post-synaptic ACh receptors?
Myasthenia Gravis
55
Where is the most common site of lesion in Myasthenia Gravis?
Thymus
56
Which thymic lesions might be present in myasthenia Gravis and which is the most common?
Hyperplasia (60%, MC)
| Thymoma (20%)
57
Extreme pes cavus is seen with what cause of peripheral nerve injury?
Charcot-Marie-Tooth Disease
58
Thymic lesions from myasthenia gravis result from
autoreactive B and T cells
59
What is the hallmark sign of myasthenia gravis?
Extraocular weakness: diplopia and ptosis
60
What gender is more commonly affected by myasthenia gravis?
Females (age 20-30)
61
What is the typical age range for males acquiring myasthenia gravis
50-70 years
62
What affect does electronic stimulation have on patients with myasthenia gravis?
worsens the condition
63
What is the survival rate of those with myasthenia gravis?
95% 5 year survival rate
64
What test is administered to patients with myasthenia gravis that may actually temporarily relieve symptoms?
The Tensilon Test (which inhibits ACh receptor antibodies)
65
What treatments are available for myasthenia gravis patients?
tymectomy, ACHase inhibitor meds; immunosuppression, plasmapheresis
66
Which third trimester teacher suffered from a unique condition known as Juvenile Ocular Myasthenia Gravis?
Dr. Roecker
67
What neuromuscular junction disorder involves the degradation of pre-synaptic calcium channels?
Lambert-Eaton Syndrome (LES)
68
What affect does electronic stimulation have on Lambert-Eaton Syndrome?
Improves conditions
69
What gender is most likely to be diagnosed with Lambert-Eaton Syndrome?
Females (2x more likely)
70
What is the usual age range for Lambert-Eaton Syndrome?
60 years of age
71
Paraneoplastic syndrome (small cell lung cancer) is associated with which neuromuscular junction disorder?
Lambert-Eaton Syndrome
72
Which type of infectious neuromuscular junction disorder causes an increase in ACh release?
Tetanus (clostridium tetani)
73
What feature is commonly seen in patients diagnosed with Tetanus?
tetanic spasm
74
What is the mode by which clostridium tetani and clostridium botulinum spread to cause infection?
through the soil
75
What condition involves decreased ACh release resulting in descending paralysis?
Botulism (clostridium botulinum)
76
If an infant (younger than 1 years old) is exposed to clostridium botulinum, what condition can occur and what is the name of that condition?
Flaccid paralysis
Floppy Baby Syndrome
77
Peripheral axons innervate multiple ______ in a ______pattern.
myocytes; checkerboard
78
Type I fibers are (slow/fast) twitch, (white/dark), (aerobic/anaerobic), and use (fat/glycogen) for energy.
slow, dark, aerobic, fat
79
Type II fibers are (slow/fast) twitch, (white/dark), (aerobic/anaerobic), and use (fat/glycogen) for energy.
fast, white, anaerobic, use glycogen
80
What is the name of a primary muscle disease characterized by muscular origin and painless weakness?
myopathy
81
What is muscle tissue replaced by as it atrophies under neuropathies and myopathies?
it is replaced by fibrotic/fatty tissue
82
Define neuropathic changes in skeletal muscle disorders?
altered innervation
83
What effect do neuropathic changes have on motor units?
they become fewer in number and larger in size
84
Disuse atrophy affects primarily what type of fibers?
type II
85
Glucocorticoid atrophy affects primarily what type of fibers?
Type II
86
Localized fractures or generalized paralysis (such as quadriplegia) could lead to which type of skeletal muscle disorder?
Disuse atrophy
87
Name the endocrine disorder that is associated with increased levels of cortisol.
Cushing Syndrome
88
What is the most common cause of Cushing Syndrome?
External corticosteroids
89
Besides external corticosteroids, what is another cause of Cushing syndrome?
Pituitary or adrenal adenoma (causes increased levels of ACTH)
90
Features such as weight gain, moon facies, purple striae, buffalo hump, insomnia, hirsutism, and infertility are all associated with what disease?
Cushing Syndrome
91
What gender is most likely to have Cushing Syndrome
Young Adult Females
92
True or False: Neuropathy is most likely associated with grouped atrophy
True
93
True or False: Myopathy is most likely associated with segmental necrosis/regeneration.
True
94
What condition is associated with a group of inherited myopathies?
Muscular Dystrophy
95
What is the function of dystrophin?
protein that keeps muscles strong
96
Define dystrohinopathies
mutated dystrophin
97
What are the two categories of muscular dystrophy?
Duchenne and Becker Muscular Dystrophy
98
Which type of Dystophinopathy is associated with absent dystrophin, and is seen by weakness by age 5, wheelchair bound by teens?
Duchenne Muscular Dystrophy
99
Which dystrophinopathy is fatal by young adulthood?
Duchenne Muscular Dystrophy
100
Which dystrophinophathy is associated with abnormal dystrophin and has an adolescent onset?
Becker Muscular Dystrophy
101
Which dystrophinopathy may have a normal life span?
Becker Muscular Dystrophy
102
List the shared features between dystrophinopathies:
clumsiness, weakness, fatigue, pelvic girdle weakness, pseudohypertrophy of calf muscles, lethal cardio-respiratory insufficiencies,, labs that show increased creatine kinase.
103
Gower's sign is associated with what condition?
Duchenne Muscular Dystrophy
104
Which toxic myopathy involves the overproduction of thyroxine?
Thyrotoxic myopathy
105
Goiter and Graves' Disease are associated with which toxic myopathy?
Thyrotoxic myopathy
106
Which toxic myopathy can be acute or chronic, and is characterized by proximal muscle weakness and necrosis?
Thyrotoxic myopathy
| He also mentioned this is a type II hypersensitivity
107
Binge drinking or rhabdomyolysis is associated with which toxic myopathy?
ethanol myopathy
108
Why can ethanol myopathy be lethal?
progresses to acute renal failure
109
Acute myalgia, myocyte swelling and necrosis are all associated with which toxic myopathy?
Ethanol myopathy
110
What is the most common cause of drug myopathy?
statins
111
Peripheral Nerve Sheath tumors are most common in what age groups?
adults
112
How do peripheral nerve sheath tumors usually manifest?
manifest as pain or loss of function
113
Are schwannomas usually benign or malignant?
benign
114
What cranial nerve is most commonly involved with a schwannoma?
C.N. VIII
115
Which type of peripheral nerve sheath tumor is 90% sporadic?
Schwannoma
116
Which type of peripheral nerve sheath tumor involves multiple CNS and cutaneous schwannomas and is familial?
Schwannomatosis
117
True or False: Vestibular Schwannomas is associated with Schwannomatosis.
False, only with schwannomas
118
Possible hearing loss or tinnitus is associated with which kind of peripheral nerve tumor?
Schwannoma
119
What is a neurofibroma?
benign nerve sheath tumor
120
Which condition involves bilateral vestibular Schwannomas?
Neurofibromatosis type 2 (NF2)
121
What is the genetic pattern of Neurofibromatosis Type 2?
Austomsomal dominant, Merlin gene invovled
122
What are the problems often seen with Neurofibromatosis Type 2?
vision and hearing problems, but no cutaneous lesions
123
Which condition involves pronounced neurofibromas and vascular stenosis?
Neurofibromatosis Type 1
124
What is the genetic pattern of Neurofibromatosis Type 1?
Autosomal dominant, mutation on chromosome 17
125
What are three visible conditions associated with Neurofibromatosis Type 1?
Lisch nodules, axillary freckling, and cafe' au lait spots
126
What are some effects of neurofibromatosis type 1?
decreased cognition and seizures
127
What is the most common location for malignant peripheral nerve sheath tumors?
plexiform
128
Cancer of Schwann cells and/or neuronal connective tissue, as well as transformed neurofibromas all may be a sign of what condition?
Malignant Peripheral Nerve Sheath Tumor (MPNST)
129
Malignant Peripheral Nerve Sheath Tumor can be seen on what parts of the body?
Arms and legs; painless and edematous
130
50% of all MPNST cases arise from patients with:
NF1 (Neurofibromatosis 1)
131
MPNST affects what percentage of all NF1 patients?
10%
132
What is the most common cause of a traumatic neuroma?
surgery
133
What is a common location for traumatic neuromas?
feet
