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Clin Med B 2 > Lecture 11: Peripheral Neuropathy Part 2 > Flashcards

Lecture 11: Peripheral Neuropathy Part 2 Flashcards

1
Q

What is Guillain Barre Syndrome?

A

Acute inflammatory demyelinating polyradiculoneuropathy resulting in symmetrical weakness and diminished reflexes

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2
Q

What breaks down myelin in GBS?

A

Antibodies

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3
Q

What are the two most common infections prior to GBS?

A
  1. Campylobacter jejuni
  2. CMV
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4
Q

What typically precipitates GBS?

A

Infectious illness in the weeks prior to onset.

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5
Q

What is the bimodal age range risk for GBS?

A
  • 15-35
  • 50-75
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6
Q

What is the MC variant of GBS?

A

Acute inflammatory demyelinating polyneuropathy

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7
Q

What are the initial symptoms of GBS?

A
  • Paresthesias moving proximally
  • Pain with minimal movement
  • Proximal muscle weakness of the LEs that ascends symmetrically
  • Muscle weakness => paralysis
  • ANS dysfunction (MC: tachycardia)
  • Diminished/absent DTRs
  • Impaired proprioception with normal sensory
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8
Q

What is the purpose of serologic studies in GBS?

A

Ruling out other DDx. They are normal in GBS

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9
Q

What would LP show for GBS?

A
  • Albuminocytologic dissociation
  • Elevated CSF protein with normal WBC count
  • Commonly positive within 1 week of onset
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10
Q

What studies confirm GBS and when are findings most prominent?

A

Electrodiagnostic studies after 2 weeks post onset

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11
Q

What findings in a MRI brain/spine with gadolinium may be seen in GBS?

A
  • Spine: Thickening and enhancement of intrathecal spine roots
  • Brain: Enhancement of cranial nerve roots
  • Highly sensitive but not specific
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12
Q

What is the managment for GBS?

A
  1. Hospitalize until plateau is achieved (12-28d)
  2. Serial bedside PFTs to check pulm muscle strength
  3. HTN: short acting BB (esmolol) or nitroprusside
  4. Hypotension via IV fluids and supine positioning
  5. Brady: atropine or pacemaker
  6. Tachy: rarely severe enough to treat
  7. Bowel sound assessments
  8. I&Os for urinary retention
  9. Immunotherapy: Plasmapheresis vs IVIG within 4 weeks
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13
Q

When is plasmapheresis or IVIG indicated in GBS management?

A
  • Non-ambulatory patients
  • Ambulatory patients that are not recovering within 4 weeks

Plasmapheresis is longer

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14
Q

How is initial pain controlled in GBS? Severe?

A
  1. Initial: NSAIDs, gabapentin, carbamazepine, amitriptyline
  2. Severe: Epidural Morphine
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15
Q

What therapists are recommended to help with GBS?

A
  • PT/OT
  • Speech therapy
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16
Q

What are the poor prognostic factors for GBS?

A
  • Old
  • Rapid onset < 1 week
  • Severe muscle weakness on administration
  • Need for vent
  • Diarrheal illness
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17
Q

How common is full recovery for GBS?

A

2/3 in 1 year

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18
Q

What is myasthenia gravis?

A

Autoimmune disorder presenting with progressively reduced muscle strength with repeated use and recovery of muscle after a period of rest.

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19
Q

What pathophysiology characterizes myasthenia gravis?

A
  1. Antibodies destroy ACh receptors and postsynaptic folds.
  2. Over-release of ACh to compensate, resulting in reduced strength and increased rest time.
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20
Q

What are the primary antibodies associated with myasthenia gravis?

A
  1. anti-AChR antibodies (MC)
  2. Anti-MuSK (Muscle-specific tyrosine kinase)
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21
Q

What organ disease is MC associated with myasthenia gravis?

A

Thymic disease

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22
Q

What drugs are known to induce or exacerbate MG?

A
  • ABX (aminoglycosides, polymyxins, cipro, erythro, and ampicillin)
  • BBs
  • Verapamil
  • Mg
  • Procainamide
  • Quinidine
  • Chloroquine
  • Penicillamine
  • Statins
  • Prednisone
  • Timolol (topical)
  • Anticholinergics
  • Lithium
  • Neuromuscular blocking agents
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23
Q

When is MG MC in males and females?

A
  • Females: 20-30 peak
  • Males: 50-70 peak
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24
Q

How does infantile MG occur?

A

Myasthenic mothers with anti-AChR antibodies that transfer via placental IgG

Transient

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25
Q

How does muscle weakness look like in MG?

A
  • Fluctuating skeletal muscle weakness
  • Worse in the evening/exercise
  • Improves with rest
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26
Q

What is the common initial presenting symptom in MG?

A
  • Ptosis
  • Diplopia
  • Weak EOM testing
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27
Q

What is bulbar weakness?

A
  • Weakness with prolonged chewing
  • Dysphagia
  • Dysarthria
  • Dysphonia

CN IX-XII

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28
Q

What happens to facial muscles in MG?

A
  • Flat affect
  • Unable to produce a smile or complete closure of eyes
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29
Q

What happens to the neck in MG later in the day?

A

Dropped head syndrome due to weakness of extensor muscles.

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30
Q

Where does muscle weakness tend to present first in MG?

A

Proximal UE

Different from GBS, which is LE.

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31
Q

What is a myasthenic crisis?

A
  • Weakness of the diaphragm and intercostal muscles
  • Preceded by increasing generalized muscle weakness and bulbar muscle weakness
  • Occurs spontaneously or precipitated by an event.
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32
Q

What is the progression of muscle weakness in MG?

A
  1. Eyes/face
  2. Neck
  3. UE
  4. Hands
  5. LE

Over 3 years

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33
Q

What is the ice-pack test?

A
  1. Ice-pack onto closed lid for 2 minutes
  2. Positive response (indicative of MG) would improve the ptosis.
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34
Q

What serology tests are used in the workup of MG?

A
  • AChR antibodies prior to starting immune modulating therapy
  • MuSK antibodies (positive => less likely to have thymic disease)
  • Seronegative MG (Most likely a purely ocular disease)
  • Anti-striated muscle Ab: MC in thymoma
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35
Q

What is a repetitive nerve stimulation study?

A
  • Modified motor NCS to stimulate the neuromuscular junction of a specific muscle.
  • Positive: smaller EPSPs
  • Negative: Normal EPSPs generate an AP.
  • MC used test for MG
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36
Q

What is a single-fiber electromyography? (SFEMG)

A
  • More Sensitive test
  • Records APs of two muscle fibers by the same axon.
  • Positive: increased interval between 1st and 2nd AP
  • NON-SPECIFIC
  • CI: people who have had botox in the past 12 months
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37
Q

What are the 4 general treatment modalities for MG?

A
  1. Sympatomatic therapy via anticholinesterase inhibitors
  2. Chronic immunomodulators (Glucocorticoids + immunosuppressants)
  3. Rapid immunomodulators (Plasmapheresis + IVIG)
  4. Surgical therapy (Thymectomy)
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38
Q

What is the first line anticholinesterase inhibitor for MG and what are the administration instructions?

A

Pyridostigmine bromide dose before eating or prior to muscle fatiguing activities

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39
Q

When do you use high dose prednisone for MG?

A
  • Hospitalized patients undergoing rapid immunomodulating therapy
  • High doses inhibit neuromuscular function
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40
Q

When do we use the other immunomodulators in chronic immunomodulating therapy?

A
  • Failure to control symptoms with just prednisone
  • CI to corticosteroids
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41
Q

When is rapid immunomodulating therapy indicated in MG?

A
  • Myasthenic crisis
  • Pre-op in MG to prevent post-op crisis
  • Bridging to chronic therapy
  • Maintaining remission when refractory to other treatment
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42
Q

When is thymectomy indicated in MG?

A
  • Thymoma
  • Young patient with generalized MG or disabling ocular MG
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43
Q

How do you treat mild-mod generalized MG?

A
  1. Symptomatic therapy
  2. Chronic immunomodulating if it remains uncontrolled
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44
Q

How do you treat severe generalized or rapidly progressing MG?

A

Rapid immunomodulating therapy + chronic + symptomatic

Add on rapid for severe

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45
Q

How do you manage ocular MG?

A
  1. Symptomatic + Chronic immunomodulating
  2. Thymectomy if needed
  3. Ptosis management (tape)
  4. Diplopia management (eye patch, opaque lens)
  5. Surgical intervention via opthalmology for stable ptosis or opthalmopheresis
46
Q

For a patient with refractory MG, how might they be treated?

A

Monthly IVIG

47
Q

How do we manage myasthenic crisis?

A
  • ICU admit
  • Rapid immunotherapy bridging with chronic immunotherapy
  • High dose glucocorticoids if no CI.
48
Q

What patient education is recommended for MG?

A
  • Avoid food that needs a lot of chewing
  • Thicken liquids
  • Exercise but avoid sustained
  • Written plan for patient
  • Avoid the meds
  • Discuss teratogenicity of pharm tx and increased risk of birth defects for MG mothers.
49
Q

What is muscular dystrophy?

A

Inherited group of progressive myopathic disorders resulting from defects in # of genes required for normal muscle function, characterized by progressive muscle weakness and wasting

50
Q

What are the two MC types of muscular dystrophy and how are they inherited?

A
  1. Duchenne type (rapid progression)
  2. Becker (slow progression)

Both are X-linked Recessive

51
Q

How do Duchenne (DMD) and Becker (BMD) differ in terms of protein?

A
  • DMD: markedly reduced or absent dystrophin resulting in rapid muscle damage with early use
  • BMD: normal dystrophin but altered shape, resulting in later onset and milder course
52
Q

What is dystrophin?

A

A protein responsible for muscle fiber strength

53
Q

Where does DMD tend to affect first?

A
  • Proximal muscles
  • LE before UE
  • Gower’s sign (hand support to get off the floor)
54
Q

What does a physical exam look like for DMD?

A
  • Unusual waddling gait
  • Lumbar lordosis
  • Pseudohypertrophy of calf
  • Shortened achilles
  • Decreased/absent DTRs
  • Mild cog impairment
55
Q

What are the complications of DMD?

A
  • DCM
  • Bone fx
  • Progressive scoliosis
  • Respiratory muscle weakness
  • Wheelchair bound by 12
56
Q

How does BMD tend to present?

A
  • Milder, later onset
  • Able to ambulate until age 15
  • Cardiac complications are more common due to retained ability to exercise
57
Q

What is the initial lab test to evaluate BMD in primary care?

A

Serum CK, which peaks by age 2 and is 10-20x ULN.

58
Q

What is the first-line diagnostic test for BMD?

A

Genetic analysis, which can confirm most cases.

59
Q

If we do a muscle biopsy for MD, what would we see?

A
  • Degeneration
  • Isolated “opaque” hypertrophic fibers
  • Replacement of muscle by fat and CT
  • Can analyze dystrophin

Muscle biopsy is rarely done now

60
Q

What is the mainstay of therapy for MD?

A

Glucocorticoids to decrease inflammation and help repair weakened muscle cell membranes

61
Q

What is the more novel treatment approach to MD?

A
  • Exon replacement therapy via Eteplirsen (Exon 51 skipping) only for DMD with specific gene mutations
  • Increased dystrophin + walking performance
62
Q

What are the two Exon 53 skippers?

A

Golodirsen & Vitolarsen

63
Q

What is the newest genetic therapy for DMD?

A
  • Creates microdystrophin
  • Only for ambulatory DMD boys aged 4-5y
  • No proven clinical benefit yet
64
Q

When is echo indicated in MD?

A

Annually

65
Q

When is cardiac MRI indicated in MD?

A

Annually once age 7.

66
Q

When are ACEIs/ARBs indicated in MD?

A

At 10 years old to reduce HF progression

67
Q

How do we prevent the osteoporosis of MD?

A
  • Calcium + Vit D supplementation
  • IV bisphosphonates (must be able to stand upright for 30 minutes to take)
  • PT and exercise
68
Q

What is the MCC of death in someone with BMD?

A

HF due to DCM

69
Q

What is Charcot-Marie-Tooth?

A

Spectrum of disorders due to mutation in myelin gene

70
Q

What is the MC type of hereditary neuropathy?

A

Charcot-Marie-Tooth (CMT)

71
Q

How is CMT inherited?

A

Autosomal dominant

MC in males

72
Q

How does CMT typically present?

A
  • Slow, progressive, distal leg weakness within 1st 3 decades
  • Foot drop
  • Pes cavus (high arch, hammer toes)
  • Foot deformities
73
Q

What happens to the legs in CMT?

A

Atrophy of the muscles, resulting in inverted champagne bottle legs or stork leg deformities

74
Q

What happens to the UE in CMT?

A
  • Hand weakness
  • Clumsiness is using small objects
  • Claw hand
75
Q

What happens to the senses and reflexes in CMT?

A
  • Diminished/absent DTRs
  • Diminished proprioception and vibratory sense
  • Pts don’t complain about subjective sensory symptoms
  • Sensory gait ataxia
  • Positive romberg
76
Q

How do we workup CMT?

A
  • EMG/NCS to confirm neuropathy.
  • Genetic testing after EMG to confirm dx of CMT
77
Q

How do we treat CMT?

A
  • Supportive
  • PT
  • Ankle-foot orthotics
  • Foot surgery
  • Avoid: Metro, macrobid, FQs, amiodarine, and colchicine (Neurotoxic drugs)
78
Q

What is the prognosis of CMT?

A

Full life span with diminished quality.

79
Q

What is the MC DM complication?

A

Diabetic neuropathy

80
Q

What exactly happens that causes DM neuropathy?

A

Vasa nervorum abnormalities occur

81
Q

How does distal symmetric polyneuropathy present?

A
  • MC form of DM neuropathy
  • Axonal neuropathy
  • Stocking-glove pattern
  • Dulled perception
  • Absent ankle DTRs
  • Calluses and ulcerations in high pressure areas
82
Q

How do we treat distal symmetric polyneuropathy?

A
  • Amitriptyline
  • Duloxetine
  • Pregabalin
  • Gabapentin
  • DM control
83
Q

What is the least common DM neuropathy?

A

Isolated peripheral neuropathy

Mainly seen in old pts

84
Q

What are the most common nerves affected in isolated peripheral neuropaty?

A
  • Ocular: CN III, IV, VI, or femoral nerves
  • Diabetic amyotrophy (lumbosacral radiculoplexus neuropathy) in anterior thigh with quads wasting
85
Q

How do you manage isolated peripheral neuropathy?

A

Same as distal + lidocaine patches

86
Q

What kind of DM typically causes autonomic neuropathy?

A

Long-term DM

87
Q

What is the primary symptom of autonomic neuropathy?

A

GI dysfunction => gastroparesis

88
Q

How do you manage GI dysfunction due to autonomic neuropathy?

A
  • Small, frequent meals
  • Metoclopramide (careful of tardive dyskinesia and extra pyramidal symptoms)
  • Loperamide for diarrhea
  • Fiber for constipation
89
Q

What medication may help with bladder dysfunction/urinary retention in autonomic neuropathy?

A

Bethanechol (cholinergic agonist) that increases detrusor muscle tone

90
Q

What medications may help with orthostasis in autonomic neuropathy?

A
  • Fludrocortisone
  • Midodrine (alpha agonist)
91
Q

How do you treat ED due to autonomic neuropathy?

A

PDE-5 inhibitors

92
Q

What body parts is alcoholic neuropathy MC in?

A

Legs

93
Q

What exactly is neurotoxic about alcohol?

A

Acetaldehyde, which is a metabolite of ethanol.

Impairs axonal transport

94
Q

What is the MC presenting complaint of alcoholic neuropathy?

A

Paresthesias of the feet and toes

95
Q

How do you manage alcoholic neuropathy?

A
  • Stop drinking
  • Thiamine supplementation
  • Low doses of TCAs or gabapentin
96
Q

What is beriberi more formally known as?

A

Thiamine/B1 deficiency

97
Q

What is thiamine’s use?

A
  • Coenzyme in carb metabolism
  • Water-soluble
98
Q

What is the primary risk factor for dry beriberi?

A

Chronic alcohol abuse

99
Q

Who does dry beriberi occur in?

A

Inactive patients with low caloric intakes

100
Q

How does dry beriberi present?

A

Symmetric peripheral sensorimotor neuropathy with loss of reflexes

101
Q

What are the more complicated CNS involvements of beriberi?

A
  • Wernicke-Korsakoff syndrome
  • Wernicke encephalopathy
  • Korsakoff syndrome
102
Q

What is the most reliable test for checking thiamine?

A
  • Thiamine loading test to assess erythrocyte transketolase activity (EKTA)
  • Positive: 10-25% increase in EKTA after thiamine administration
103
Q

How do you treat thiamine deficiency?

A

Thiamine until proper nutrition is restored

104
Q

What exactly occurs due to a lack of Vit B12?

A

Damage to the myelin sheath

105
Q

What is the MCC of Vit B12 deficiency?

A

Pernicious anemia

106
Q

How does a B12 deficiency present?

A
  • Paresthesias of the hand, followed by LE
  • Sensory changes
  • Sensory ataxia
  • Anemia
  • Glossitis
  • Optic atrophy
  • Behavioral changes in severe cases
107
Q

How do we confirm B12 deficiency?

A

Reduced serum B12/cobalamin levels

108
Q

What serologic tests may be ordered to check for pernicious anemia?

A
  1. Antiparietal cell antibodies (90%)
  2. Intrinsic factor antibodies (60%)
109
Q

What ist he standard treatment for B12 deficiency?

A
  • 1000 mcg of IM B12 weekly for 1 month
  • 1000mcg a month
110
Q

How does neuropathy associated with gastric surgery present?

A
  • Rapid, significant wt loss
  • Recurrent, protracted vomiting
  • Numbness and paresthesias in the feet is the initial symptom
111
Q

Why are the feet most commonly affected in neuropathies?

A

The longest nerve/axon is the sciatic nerve

112
Q

How do you treat gastric surgery neuropathy?

A

Vitamin supplements, especially thiamine

Clin Med B 2 (44 decks)

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