MG

Question 1

A patient presents with ptosis, diplopia, difficulties with chewing and swallowing, and an expressionless face, what diagnosis?

Answer 1

Myasthenia Gravis

Question 2

What is MG?

Answer 2

(Rare) Autoimmune disease that involved antibodies against the Ach receptors at the neuromuscular junction and muscle specific receptor tyrosine kinase

Question 3

What lab abnormality is present in most patients with MG?

Answer 3

Thymic abnormalities (Thymus is where T cell mature)

Question 4

What must you always remember with MG?

Answer 4

“Ming to Ground” = It presents in a descending pattern

Question 5

What signs and symptoms are common with MG?

Answer 5

Fatigue, eye, speech, and swallowing difficulties. Can then progress down to the respiratory muscles.

Often better in the morning

Question 6

There are lots of triggers for MG, what are some general categories?

Answer 6

Anesthetics, neuromusclular blocking agents, Abx, anticonvulsants, Penacillamine, cardio meds, steroids, muscle relaxants, ophthalmic drugs.

Question 7

What is penicillamine?

Answer 7

A medication used as a form of immunosuppression to treat RA

Question 8

What might you find on PE in MG?

Answer 8

Fatigability of muscles! (lay down and then look up, the lids eventually drop). Normal sensation, normal reflexes. Slack jaw and ptosis on exam

Question 9

Put the MG patient’s head down and force them to look up, you notice lid fall. What’s the name of this test?

Answer 9

Simpson test

Question 10

If a MG patient’s follows your finger up and down, and as you go up one lid lags. What’s this test?

Answer 10

Cogan lid twitch sign

Question 11

What are two tests you can do to confirm the diagnosis of MG?

Answer 11

Tensilon Test (Short-acting Ach-esterase inhibitor) = if marked clinical improvement

Ice pack test = neuromuscular transmission is improved at cooler temperatures

Question 12

What blood tests can be done to confirm the diagnosis of MG?

Answer 12

Seropositive for Ab against Ach receptors (NACHR – nicotinic acetocholinesterase receptor) or Muscarinic Tyrosine Kinase (MUSK)

Mostly go with binding

Question 13

What if a patient is seronegative but still have the sxs and confirmatory tests are positive?

Answer 13

May still be MG but need to consider other autoimmune diseases

Can also do Electrophysiologic testing

Question 14

What if on a CT an incidental finding of thymus abnormalities is seen, what should you do?

Answer 14

Consider Ab testing for MG

Question 15

What electrophysiologic test finding would confirm MG?

Answer 15

Repetitive nerve stimulation = A “U” shape

Question 16

There is no cure for MG, but what are some treatment options?

Answer 16

Acetylcholinesterase inhibitors; immunomodulation; immunosuppression (corticosteroids); surgery; IV-Ig & PLEX (for respiratory distress)

Question 17

How does an Acetylcholinesterase inhibitor work?

Answer 17

Inhibits enzymes that breakdown Ach – works for about an hour

Question 18

What treatment is best for younger patients to create symptomatic relief and possibly lead to remission?

Answer 18

Thymectomy – but can take up to 10 years for remission

Question 19

If a patient has a slow progression of their FVC, as monitored in the ICU, what is going on?

Answer 19

Respiratory Crisis

Question 20

What are the treatment options for respiratory crisis?

Answer 20

IVIg - ~$10,000 per infusion

Plasma Exchange (PLEX) – primary choice

Question 21

How do you classify MG?

Answer 21

1-5 (5 = the worst with intubation)