Robbins - Peripheral Nerves and Muscles (Ch. 27) Flashcards Preview

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Flashcards in Robbins - Peripheral Nerves and Muscles (Ch. 27) Deck (59)
1

3 common causes (general) of mononeuropathies

Trauma
Entrapment/impingement
Infections/malignancy

2

Polyneuropathies - how do they generally present?

Symmetric, start in hands/feet and ascend ("Stocking and glove" distribution)

3

Common cause of mononeuritis multiplex

Vasculitis

4

Polyradiculoneuropathies also involve the ____, leading to symmetric symptoms in the distal AND ___ body

Nerve roots

Proximal

5

Acute motor weakness or paralysis in hands and feet that rapidly progresses to proximal muscles. DTRs are absent. Recently was sick.

What is it?


What PMH questions would you ask?


Worst complication?

Guillain-Barré Syndrome (Acute Inflammatory Demyelinating Polyneuropathy)

Autoimmune-mediated inflammation and demyelination of peripheral nerves and spinal nerve roots

Recent pneumonia? Recent viral illness? Recent GI infection?

Respiratory paralysis

6

Guillan-Barré -- inciting incident? Which ones?

INFECTION
- Mycoplasma pneumonia
- C. jejuni enteritis
- HIV, CMV, EBV viral illness

7

Diagnosing Guillan-Barré (3)

- CSF protein elevated
- No CSF pleocytosis
- Slow nerve conduction

8

Treating Guillan-Barre´ (2)

- Plasmapheresis
- IVIG

9

Relapsing and remitting symmetric sensory and motor deficits in the extremities for the past 2+ months. IgG and IgM are found on the myelin sheaths of peripheral nerves. Responds well to steroids.

Chronic Inflammatory Demyelinating Polyradiculoneuropathy

10

Systemic autoimmune diseases that can cause sensorimotor neuropathy (3)

RA, Sjogren, SLE

11

Loss of pain and sensation in all distal extremities and face. Segmental demyelination is found. Large ulcers found on extremities.

Lepromatous leprosy (M. leprae)

12

Dermal nodules of granulomatous inflammation. Surrounding skin has loss of pain and sensation.

Tuberculoid leprosy (M. leprae -- cell-mediated immunity)

13

Bilateral bell's palsy, target-like lesion on skin

Lyme disease

14

Immigrant from S. America, fever, gray-white patches in throat, sudden peripheral muscle weakness and difficulty breathing.

Diphtheria

15

Painful, vesicular skin lesions within a band-like pattern on the thorax or face

VZV (shingles)

16

Most common cause of peripheral neuropathy

What kind of neuropathy is it? What is found on biopsy?

What is the cause?

Diabetes mellitus

Axonal (decreased number of axons)

Abnormal glycosylation of neural tissue, causing destruction

17

Patient with DM has distal polyneuropathy with numbness, difficulty w/ balance, paresthesias or dysesthesias. What other findings are common (20-40%)? Examples? (3)

Autonomic dysfunctions
- Postural hypotension
- Incomplete bladder empty
- Sexual dysfunction

18

A patient w/ DM develops neuropathies, some of which are unilateral and asymmetric. What is the cause for these ones?

Microvascular disease, causing ischemia to those particular nerves

19

Uremia produces what kind of peripheral neuropathy?

Symmetric axonal degeneration

20

Hypothyroidism causes what kinds of peripheral neuropathy? (2)

Compression neuropathies or distal symmetric sensory neuropathies

21

Most common toxic cause of peripheral neuropathy?

Alcohol abuse

22

Most common paraneoplastic form of peripheral neuropathy

What does the damage? To what?

Presentation?

Small cell lung cancer --> sensorimotor neuronopathy

CD8+ T cells on dorsal root ganglion cells

Distal, asymmetric, multifocal neuropathy that progresses

23

What are paraproteins? Do what?



Distinctive presentation of this?

Monoclonal Ig fragments from neoplastic B cells that bind to neurons and cause immune-mediated demyelination

POEMS syndrome -- polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, skin changes

24

Common neuropathies caused by physical forces (trauma or entrapment) (5)

Compression neuropathy
Carpal tunnel syndrome
Ulnar nerve entrapment
Saturday night palsy (Radial)
Peroneal nerve

25

An adult with a peripheral neuropathy. Do NOT rule out an _____ disease

Inherited - often present in adults

26

Distal LE muscle atrophy, sensory loss, and foot deformities. Leg has "inverted bottle" appearance.

What is it?

Genetics? (3)

Charcot-Marie-Tooth disease

Group of inherited disorders that cause PERONEAL nerve neuropathy.

CMT1 = AD, defective myelin

CMTX = X-linked, defective gap junction in schwann cells

CMT2 = AD, axonal injury due to defective mitochondrial fusion -- SEVERE, EARLY

27

Transient motor and sensory mononeuropathies triggered by compression at common sites of entrapment

Genetics? Causes what finding?

Hereditary neuropathy w/ pressure palsy

PMP22 (same as CMT1) -- myelin defect -- swollen bulbous myelin sheaths at ends of internodes

28

Painless weakness of a muscle...think what?

Most common cause?

NMJ impairment

Autoantibodies

29

Patient experiences progressive muscle weakness over the course of the day, worse with exercise or exertion. Can't keep her eyes open, and sees double.

Patient is young or middle age. What else to look for?

Relationship between these?

Myasthenia gravis

Thymoma or thymic hyperplasia (B-cell follicles in the thymus)

Thymic disease promotes formation of autoimmunity against acetylcholine receptors on thymic myoid cells

30

Myasthenia gravis is caused by what?

Autoantibodies against post-synaptic acetylcholine receptors

31

Patient has weakness of extremities that improves after a few seconds of activity. Dx?

Cause?

What else to look for?

Lambert-Eaton Myasthenic Syndrome

Autoantibodies against presynaptic calcium channels, preventing acetylcholine release

Neuroendocrine (small cell) carcinoma of the lung OR an autoimmune disease (vitiligo, thyroid disease, etc.)

32

Function of botulinum toxin


Function of curare

Block release of acetylcholine from presynaptic neurons

Block acetylcholine receptors, causing flaccid paralysis

33

Slow-onset symmetrical proximal muscle weakness and muscle aches. Has trouble getting up from a chair or walking up stairs. Rash around the upper eyelids with edema, or a red scaly rash over joints.

May see what on biopsy of muscle or skin? (2)

See what on labs? (2)

What are those skin rashes called? (2)

May also have what?

Dermatomyositis

- Perifascicular atrophy of muscle fibers
- Deposition of C5-C9 (MAC) within capillary beds

- Elevated CK
- Anti-Mi2/Jo1/P155 autoantibodies

Heliotrope rash (lilac-colored)
Gottron papules


Paraneoplastic-producing malignancy

34

How does polymyositis differ from dermatomyositis? (2)

- No cutaneous features
- No perifascicular atrophy

35

How does inclusion body myositis differ from polymyositis? (3)

- Late adulthood (65+)
- Quads and distal UE muscles
- cN1A antibody

36

How to treat inflammatory myopathies?

Corticosteroids

37

A patient with obesity and hypercholesterolemia is taking a statin to lower his cholesterol. What is the most common complication of this drug?

MYOPATHY (toxic)

38

Infant presents with severe hypotonia (floppy infant)...what disease class?

Most important genetic? Causes what in infants? (2)

Causes what in adults?

Congenital myopathies

RYR1 (ryanodine receptor) mutation -- hypotonia and skeletal abnormalities

MALIGNANT HYPERTHERMIA

39

Muscular dystrophies present when?

Childhood to adulthood (NOT INFANCY)

40

Young child (2-5), delayed walking, weakness and atrophy of pelvic muscles. Must place hands on knees to stand up. Labs show normal CK. Dx?

Cause?

Will see what else on observation? Why?

Will find what else on physical exam? (2)

Common causes of death?

Duchenne muscular dystrophy

X-linked frameshift mutation, causing absence of DYSTROPHIN gene

Fibrosis and fatty infiltration of muscle tissue, causing pseudohypertrophy of calf muscles

Cardiomyopathy/arrhythmias and cognitive impairment

Respiratory insufficiency, pulmonary infection, or HF

41

How does Becker muscular dystrophy differ from Duchenne?

- Later in childhood or adult
- Full life prognosis
- Defective but present dystrophin
- Much less severe

42

CK levels in muscular dystrophy


What part(s) of muscle is lost?

Elevated in 1st decade of life, then declines as muscle mass is lost

Type 1 AND Type 2 fibers

43

Sagging face, can't close mouth, sustained grip or involuntary contraction of muscles

Genetics?

What part(s) of muscle is lost?

Myotonic dystrophy

CTG trinucleotide repeats

Type 1 Fibers ONLY

44

Slowly progressive humeroperoneal weakness, cardiomyopathy, and early contractures of tendons

EMD1/2 mutation - what proteins?

Emery-Dreifuss Muscualr Dystrophy

Nuclear lamina protein mutations

45

Prominent weakness of facial muscles and muscles of shoulder girdle. DUX4 over-expression.

Fascioscapulohumeral dystrophy

46

Patient has episodes of severe muscle cramping and pain after exercise or during fasting. Most likely has a disease associated with defective ____

Severe cases may present with ____

Lipid or glycogen metabolism/storage


Rhabdomyolysis (necrosis)

47

Patient presents with chronic muscle weakness and elevate serum CK. On PE, extraocular eye muscles appear weak. Must think what kind of disease? Why?

Mitochondrial myopathies

Extraocular muscles have the most mitochondria per mass of any muscle

48

An infant presents with generalized hypotonia, especially of proximal (thorax) muscles and respiratory muscles. SMN1 mutation is found.

Cause?

Spinal muscular atrophy

Loss of motor neurons

49

Mutations in ion channels can cause what major clinical manifestations? (5)

- Epilepsy
- Migraine
- Cerebellar dysfunction
- Peripheral nerve disease
- Muscle disease

50

What is the ryanodine receptor?

2 diseases when dysfunctinal?

Regulator of calcium release from sarcoplasmic reticulum

Congenital myopathy
Malignant hyperthermia

51

Tachycardia, tachypnea, muscle spasms, hyperpyrexia

Triggered by what?

What causes the symptoms?

Malignant hyperthermia

Halogenated inhalational agents, succinylcholine

Excessive calcium efflux from SR --> tetany and excessive heat production

52

Well-circumscribed encapsulated mass that abuts a nerve without invading it. Palisading nuclei, Antoni A/B, Verocay bodies.

Most common nerves? (3)

Genetics?

Schwannoma

Vestibular br. of VIII
Branches of V
Branches of dorsal roots

NF2

53

Mass at the cerebellopontine angle, tinnitus and hearing loss

Common name?

Schwannoma

Acoustic neuroma

54

Mass of neoplastic Schwann cells, perineural cells, fibroblasts, mast cells, and CD34+ spindle cells

Genetics?

3 types


Bad prognosis?

Neurofibroma

NF1

- Superficial cutaneous (pedunculated nodules)
- Diffuse (large plaque-like)
- Plexiform (w/ nerve roots or large nerves)

PLEXIFORM --> MPNST

55

Poorly defined, infiltrative mass in the chest, abdomen, pelvis, neck, or limb girdle. Focal areas of random differentiation (glandular, cartilagenous, osseous).

2 types?

Malignant peripheral nerve sheath tumor

- NF1 - from plexiform neurofibroma
- Sporadic (de novo)

56

Poorly defined, infiltrative mass in the chest, abdomen, pelvis, neck, or limb girdle. Focal areas of rhabdomyoblastic morphology.

Triton tumor (MPNST)

57

NF1 - tumors (5)

- Neurofibromas
- MPNSTs
- Gliomas of optic nerve
- Glial/hamartomatous tumors
- Pheochromocytoma

58

NF1 - non-tumor features (4)

- Lisch nodules (pigmented spots on iris)
- Cafe au lait spots
- Mental retardation
- Seizures

59

NF2 - tumors (3)

- Bilateral 8th nerve schwannomas
- Multiple meningiomas
- Ependymomas of spinal cord