B2W2 Trans Phys

Question 1

Myasthenia Gravis

Answer 1

Autoimmune disorder caused by antibodies attacking the AChrs at the neuromuscular junction

Question 2

Pathophysiology of T-Cells binding to AChr

Answer 2

Activates complimentary membrane attack complexes
Decreases AChr’s effectiveness
Directly blocks AChr’s

Question 3

Non T-Cell MG

Answer 3

Caused by MuSK and LRP4

Question 4

Symptoms of MG

Answer 4

Initial signs may be droopy lids, double vision, and bulbar weakness.

Main symptom is generalized muscle weakness which worsens throughout the day but improves with rest

Question 5

Diagnoses of MG

Answer 5

Tensilon Test, AChr antibody serum test, MuSK serum test, and electrodiagnostic studies

Question 6

Electrodiagnostic studies

Answer 6

Nerve and Needle test, Slow repetitive nerve stimulation, and single fiber EMG

Question 7

Repetitive Nerve Stimulation

Answer 7

Slow RNS is used because it allows for the depletion of Primary ACh stores without the accumulation of Ca2+ in the presynaptic terminal

In about 60% of MG patients EPP will begin to decrease.

Question 8

Slow RNS in NMJ defect determinants

Answer 8

A 10% difference in amplitude between the 1st and 4th response

Question 9

Tensilon Test

Answer 9

Administration of an Acetyl Choline Esterase inhibitor prevents the ACh in the synaptic cleft from degrading which allows for more ACh to bind to receptors

~90% MG Patients

Question 10

AChR Serum Antibodies

Answer 10

Detects the presence of AChR Antibodies in MG Patients
80% in Generalized MG Patients
55% in Ocular MG Patients

Question 11

MuSK Antibodies

Answer 11

If AChR antibody test is negative MuSK is searched for instead.

Mainly Bulbar symptoms and not as many eye and limb symptoms

Question 12

Single Fiber EMG

Answer 12

Most Sensitive test for the presence of an NMJ defect, but not specific. Used if slow RNS in non conclusive.

Question 13

Voluntary SFEMG

Answer 13

Most widely used requires patient participation. Patient contracts muscle fiber

Question 14

Stimulation SFEMG

Answer 14

Nerves are stimulated without the need for patient participation

Question 15

Chest Imaging

Answer 15

CT/MRI used to determine the presence of a thymoma or thymus gland tumor

Question 16

Thymic hyperplasia

Answer 16

Enlarged thymus gland. Removal is recommended

Question 17

Myasthenia Exacerbation

Answer 17

Worsening symptoms without the need for intubation

Question 18

Myasthenia Crisis

Answer 18

Sever worsening of respiratory symptoms.
Requires incubation

Question 19

Causes of Myasthenia Crisis

Answer 19

Infection
Medication
Uncontrolled Disease
Stress

Question 20

Inpatient Treatment for MG

Answer 20

Difficulty breathing/swallowing
Moderate to severe exacerbation
Myasthenia Crisis

Question 21

Outpatient Treatment for MG

Answer 21

Pyridostigmine (Mestion) - Oral medication AChE inhibitor
Prednisone - Most common medication used for MG
Steroid Sparing Immunosuppressants (Cyclosporine) - Good in long term but takes time to work
Thymectomy - Thymus removal

Question 22

Absolute Contraindications (Life Threatening for MG patient)

Answer 22

Curare and Botox

Both cause paralysis which is not what you need when your muscles are weak

Question 23

Contraindications (Should Avoid for MG patients)

Answer 23

Antibiotics (Z-packs, Ciprofloxacin)
Anti-arhythmics
Magnesium
Antimalarials

Question 24

Use with caution for MG patients

Answer 24

Antihypertensives
Lithium
Statins

Question 25

Inpatient Treatment for MG

Answer 25

Airway assistance, cardiac monitoring, discontinue offending drugs, treat infection, and provide prophylaxis

Question 26

Specific Treatment

Answer 26

Rescue Therapy
Removal of 1-1.5x plasma volume on each session for 3-5 sessions
Intravenous immunoglobulin for 5 days

Question 27

Lambert Eaton Myasthenic Syndrome (LEMS)

Answer 27

Presynaptic NMJ disorder where the antibodies attach P/Q type voltage gated Ca2+ channels

Question 28

LEMS Symptoms

Answer 28

Similar symptoms to MG but muscle weakness improves with exercise

Question 29

LEMS Physical Exam

Answer 29

Proximal muscle weakness - muscles improve with repeated usage
Areflexia - muscles do not respond to stimuli
Dyspnea/dysphagia - shortness of breathe and trouble swallowing
Ataxia - lack of coordination

Question 30

LEMS Diagnostic Testing

Answer 30

Anti P/Q type voltage gated calcium channel serum antibodies. 85-90% LEMS patients

Rapid Repetitive Nerve Stimulation (20-50 Hz) - Increase mobilization of ACh Stores

Question 31

Rapid RNS

Answer 31

20-50 Hz
Promotes accumulation of Ca2+ in the presynaptic cleft promoting ACh release
In presynaptic defects EPPs do not reach threshold at baseline

Question 32

LEMS Treatment

Answer 32

3,4 diaminopyridine - K+ Channel blocker which prevents hyperpolarization which prolongs depolarization thus increasing the Ca2+ entry

Question 33

Botulism

Answer 33

A neurotoxin usually obtained from home canned food or unpasteurized honey

Question 34

Botulism Symptoms

Answer 34

24-36 hours Severe facial weakness
Oculobulbar weakness
Slurred Speech
Descending weakness

Question 35

Botulism Pathophysiology

Answer 35

At the presynaptic neuron of the NMJ botulism toxin cleaves SNARE proteins preventing vesicle fusion with the cell membrane
Less ACh is released resulting in a smaller CMAP
Exercise will improve CMAP

Question 36

Unique Botulism Symptom

Answer 36

Fixed Pupillary Dilation

Question 37

LEMS Vs. Botulism

Answer 37

LEMS repeated stimulation causes EPP increase of 150-300%
Botulism repeated stimulation causes mild EPP increase of 50-200%