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Robbins Pathology MSK (Chapters 24,25,26) > Chapter 26- Peripheral Nerves And Muscles > Flashcards

Chapter 26- Peripheral Nerves And Muscles Flashcards

(101 cards)

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1
Q

What are the portions of myelinated nerves separated by

A

Internodes called Nodes of Ranvier

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2
Q

What supplies the myelin sheat for each internode

A

Single schwann cell

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3
Q

What is the epineurium

A

Enclosed entire nerve

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4
Q

What is the perineurium

A

Multilayered, concentric connective tissue sheath that encloses each fascicle

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5
Q

What is the endometrium

A

Surrounds the individual nerve fiber

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6
Q

What is the result when there is Schwann cell demyelination

A

Segmental demyelination, with loss of myelin

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7
Q

What is the result when there is axonal degeneration

A

Primary involvement of the neuron and its axon

*May be followed by axonal regeneration and reinnervation of muscle

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8
Q

What is a denuded axon

A

Stimulus in the axon for remyelination

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9
Q

What is the length of neurons that have been remelinated following injury

A

Shorter than normal

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10
Q

What is the first thought when there is the appearance of onion bulbing of a neuron

A

There is degeneration of axon as it is losing and unraveling of the myelin

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11
Q

What is a traumatic neuroma

A

There is a trauma to the nerve, and rather than the repairing in the parallel normal fiber pattern, there is haphazard whirled proliferation that is prone to painful nodules

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12
Q

What are myelin ovoids

A

Schwann cell’s catabolize myelin and then later engulf the axon fragments, which produce small oval compartments

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13
Q

What is the result when muscles lose innervation due to axonal degeneration

A

Denervation atrophy

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14
Q

What are angulated fibers

A

Atrophic fibers are smaller and triangular shape when denervation atrophy

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15
Q

What are target fibers when there is axonal degeneration

A

Rounded zone of disorganized myofibers in center of the muscle fiber

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16
Q

What determines the muscle fiber type

A

The motor neuron, as all muscle fibers of a single unit are of the same type

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17
Q

What is steroid atrophy

A

During glucocorticoid therapy, type 2 muscles can atrophy

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18
Q

What is segmental necrosis

A

Destruction of a portion of myocyte, followed by myophagocytosis, which leads to the deposition of collagen and fat

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19
Q

During regeneration of muscle fibers, what changes are seen with regards to the nuclei

A

Regenerating portion has a large, internalized (central location) nuclei with Prominent nucleoli, and cytoplasm that is laden with RNA that is Red

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20
Q

What is mononeuritis pultiplex and what is a common cause

A

Several nerves damaged in a haphazard fashion

*Usually cause by vasculitis, such as polyarteritis nodosum.

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21
Q

What is the cranial nerve that can cause facial muscle paralysis

A

Cranial nerve 7

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22
Q

What is Bell’s palsy

A

One sided facial drooping

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23
Q

What is associated with causing Bell’s palsy

A
  • Upper respiratory infection

- Diabetes mellitus

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24
Q

What are the common causes for neurogenic bladder

A

Aka lack of control of urinary conditions due to an underlying issue

1) Nerve damage (seen in MS or parkinson, or DM)
2) Infection/injury of brain or SC
3) Heavy metal poisoning
4) Spina bifida and other congenital SC issues

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25
What are the state of the reflexes and order or paralysis in Guillain-Barre
Deep tendon reflexes disappear *Ascending paralysis
26
What are the common caused of GBS
*2/3 proceeded by acute influenza like illness - CMV - EBV - Mycoplasma - prior vaccination
27
What portion of the neuron tends to be affected by GBS
- Perivenular and endometrial infiltration with inflammatory cells - segmental demyelination
28
Are antibodies present in GBS
Yes, they are antimyelin Abs
29
What are the cytoplasmic processes involved in GBS
Macrophages penetrate basement membrane of Schwann cells, particularly near the Nodes of Ranvier
30
What are the lab CSF values in the cause of GBS
- Increased protein (due to permeability of spinal roots) | - Normal inflammatory cells (they are confined to the roots)
31
What are the common causes of death in GBS and what is the treatment
Respiratory paralysis Autonomic instability Cardiac arrest *Treatment is plasmaphareisis or IVIg
32
How is chronic inflammatory demyelination get polyradiculneuropathy differentiated from GBS
- It will respond to steroids | - symptoms will be present for >2 months
33
What is the classic histological finding in the case of chronic inflammatory demyelinating polyradiculoneuropathy
Onion bulbs
34
What are the characteristics at the neuron level in leprosy
- Segmental demyelination - remyelination - Loss of both myelination and unmyelinated axons -Endoneuronal fibrosis and multilayered thickening of perineural sheaths
35
Which neurons tend to be affected in leprosy
Cool extremities (lower temps for the Mycobacterium to growth)
36
Which fibers tend to be affected in leprosy
Pain fibers, with the loss of sensation contributing to injury
37
What are the neurons that tend to be affected during infection with diptheria
Selective demyelination of axons that extend into the anterior and posterior roots, along with mixed sensorimotor nerves q
38
How does VZV cause damage to neurons
Infects the neuron, then causes the loss of the affected ganglion, leading to regional necrosis and hemmorhage **Loss of the dorsal root sensory ganglion results in axonal degeneration of peripheral nerves
39
What kind of neuron damage is occuring in DM
Segmental demyelination with loss of small myelinated and unmyelinated fibers *Also loss of autonomic fibers
40
Which thyroid dysfunction can result in neuropathy
Hypothyroidism
41
Which paraneoplastic syndromes can cause neuropathy
Small cell lung cancer
42
Which neoplasms can cause neuropathy
B cell neoplasms (monoclonal gammopathies)
43
What are the syndromes that B cell neoplasms can cause
- Polyneuropathy - Orangomegaly - Endocrinopathy - Monoclonal gammopathy - skin changes
44
Which nerve is affected in saturday night palsy
Radial nerve upper arm
45
WHich nerve can be affected at the knee
Fibular nerve
46
What is Morton neuroma
- Metatarsalgia - Interdigital nerve @ intermetatarsal sites *Perineural fibrosis is histological findings
47
What is the most common inhereted peripheral neuropathy
Charcot-Marie-Tooth (CMT)
48
What is the inheritance pattern and gene in CMT1
Autosomal dominant -Chromosome 17, peripheral myelin protein (PMP22) *Seen in the second decade of life
49
What is the inheritance form of CMTX
X linked
50
What is the inheritance pattern and gene present in CMT2
Autosomal dominant Due to axonal injury - MDN2 gene, normal mitochondrial fusion * Seen in early childhood
51
What is the mechanism of disease in the case of myasthenia gravis
There are antibodies that target the acetylcholine receptors
52
What is the mechanism of disease in Lambert-Eaton
Antibodies block ACh release by inhibiting the presynaptic calcium channel
53
In those patients with myasthenia gravis who do not have Abs to AChR, what are they to
Sarcolemmal protein muscle specific receptor tyrosine kinase
54
What is the most common causes for Lambert-Eaton Myasthenic syndrome
Paraneoplastic conditions, with about 50 being from a small cell lung cancer
55
What is the staining in the cause of myocytes undergoing regenerations
Basophilic staining, aka RED due to the height number of RNA
56
When does dermatomyositis commonly occur
4th-6th decade
57
What conditions has a distinctive lilac or helipotrope discoloration of upper eyelids and periprbital edema
Dermatomyositis
58
Which lesions are commonly seen with dermatomyositis
- Lilac with eyelids - telangiectasias of nail folds, eyelids, and gums - Groton lesions
59
What are Groton lesions that are associated with dermatomyositis
Scaling erythematous eruptions or dusky patches over the knuckles, elbows, or knees
60
Which muscles tend to be affected first with dermatomyositis
Proximal muscles (raising chair or climbing stairs)
61
What conditions are those with dermatomyositis at an increased risk for
- dysphagia (oropharyngeal and esophageal muscles) - Interstitial lung disease - Cardiac involvement **Increased visceral cancer risk
62
What are the autoantibodies that are commonly present in dermatomyositis
Anti-Mi2 Anti-Jo1 AntiP155/P140
63
In those with dermatomyositis, which symptoms are expected in the presence of autoantibodies to: -Anti-Mi2
Heliotrope rash and Groton papules
64
In those with dermatomyositis, which symptoms are expected in the presence of autoantibodies to: -anti-Jo1
Mechanic hands
65
In those with dermatomyositis, which symptoms are expected in the presence of autoantibodies to: -antiP155/P140
Paraneoplastic and juvenile cases
66
What is the common histological findings in dermatomyositis
Perifascicular atrophy *Atrophic fibers grouped at the periphery of fascicles
67
In juvenile dermatomyositis, which organs are commonly affected
* most common myopathy of children | - Involves the GI (mucosal ulcers, perforation)
68
During polymyositis, which muscles are affected first
Symmetrical proximal muscle involvement
69
What is the clinical features seen in a patient with polymyositis
Myalgia and weakness Adult onset No Cutaneous features *Diagnosis of exclusion
70
What are the histological findings in polymyositis
CD7 T cells in the endometrium, necrotic and regenerating fiber scattered through the fascicle * endomysial mononuclear infiltrate (differentiated that dermatomyositis) * *Random distribution of affected fibers
71
What is the clinical features of inclusion body myositis
Slowly progression of muscle weakness, especially in the quadriceps and distal UE *Starts with the distal muscle and extensors of knees and flexors of wrists and fingers (asymmetric)
72
Rimmed vacuoles are seen in which condition
Aka inclusions with reddish granular rimming Highlighted by Basophilic granules around the periphery, endpmysial fibrosis seen in inclusion body myositis
73
What is the treatment for inflammatory myopathies
Usually responds poorly to steroids
74
Chloroquine and hydroxychloriquine commonly affect which part of the body
*Used in the treatment of malaria Causes lysosomal storage myopathy, leading to slowly progressing muscle weakness due to type 1 fiber disruptions
75
Alcohol binge drinking can have what effect on muscles
Rhabdomyolysis
76
What is the gene affected in DMD
Xp21, which codes of dystrophin
77
What is the level of dystrophin in the case of DMD
Absent
78
What is the level of dystrophin in the case of BMD
Decreased amount of DMD
79
Which complication tends to arise in those with DMD or BMD
Cardiac manifestations
80
What i sthe state of muscle size in those patients with DMD
Enlarged due to increased bulk that turns to fat and connective tissue
81
What is myotonia seen during myotonic dystrophy
Sustained contraction of a group of muscle *Can be elicited by percussion on the thenar eminence
82
What is the genetic component seen during myotonic dystrophy
CTG trinucleaotide repeats leading to DMPK
83
What are the symptoms in a patient with myotonic dystrophy
- Stiffness, difficulty releasing grip - Skeletal muscle weakness - cataracts - Endocrinopathy - Cardiomyopathy
84
Which condition can be described with: - Ring fiber - Sarciplasmic mass - Hatchet face
Myotonic dystrophy
85
Patients with emery dreifuss muscular dystrophy (EMD) have mutation in which gene
EMD1 (x linked) EMD2 (AD) *Both code for nuclear lamina proteins
86
What is the triad seen in those patients with emery dreifuss musclar dystrophy (EMD)
1) Slowly progressing hymeroperoneal weakness 2) Cardiomyopathy with conduction defects 3) Early contractures of the Achilles’ tendon, spine, and elbows
87
What is the most common disease of lipid or gylcogen metabolism
Carnitin palmitolytransferase 2
88
What are the symptoms seen in those with carnitine palmitolytransferase 2
Episodic muscle damage with exercise and fasting
89
What are the lab values that will be seen in those with mitochondrial myopathies
Weakness, increased serum creatinine kinase, rhabdomyolysis
90
What are the muscle commonly seen to be affected in those with mitochondrial myopathies
Extraocular muscle involvment *Chronic regressive external ophthalmologist common
91
What is the mutation in Levers
Point mutation in mitochondrial DNA leading to hereditary optic neuropathy
92
What is the conditions being caused by Leigh syndrome
Subacute necrotizing encephalopathy
93
What is the condition being caused during Barth syndrome
Infantile x linked cardio skeletal myopathy
94
What is the condition being caused during Kearns-Sayre syndrome
Weakness of the extraocular muscles Deletions or duplication of the mitochondrial DNA *Also will ahve ophthalmoplegia, pigmentary degeneration of retina, complete heart block
95
What does red, trichromatic stains showing “ragged” fibers mean
Aka aggreagated of abnormal mitochondria under the sarcolemma with distortion of myofibrils **aka parking Lot inclusions
96
What is the congenital cause of floppy infant due to
Spinal muscular atrophy
97
What are some of the symptoms seen in spinal muscular atrophy
``` Congenital: -Myotonia -Myopathy -muscular dystrophies Encephalopathy ```
98
Muscular trophy destroys what component
Anterior horn cell of the SC
99
What is the gene factor affected in spinal muscular atrophy
Survival motor neuron 1 (SMN1)
100
What is the most common form of spinal muscular atrophy
Wernig Hoffman (SMA type 1) * onset at birth, floppy baby and death <3 yo * Truncal weakness and loss of chewing swallowing, and breathing
101
Which gene and product is the result of malignant hyperthermia
RYR1 mutation, leading to events in the calcium channel

Robbins Pathology MSK (Chapters 24,25,26) (7 decks)

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