Myasthenia Gravis Flashcards Preview

neuroinflammation > Myasthenia Gravis > Flashcards

Flashcards in Myasthenia Gravis Deck (14):
1

what is the prevalence of myasthenia gravis?

15 per 100,000 in the UK

2

what are the three different presentations of Myasthenia Gravis?

pure ocular Myasthenia Gracis

generalised Myasthenia Gravis

Crises (Myasthenic and cholinergic crisis)

3

what is one of the most common symptoms of ocular MG

ptosis (drooping /fatigue of eyelid)

4

what are some common features of Generalised Myasthenia Gravis?

usually ocular disease plus weakness of another muscle group such as :

bulbar function
proximal weakness
respiratory weakness

5

what clinical examination is useful in myasthenia gravis?

test for muscle fatigue

6

what investigations are useful when diagnosing myasthenia gravis?

antibody tests
edrophonium test
EMG

7

what is the ice test?

when ice is applied to the eye lids, the patient can open their eyes for around 40 seconds, then the eyes begin to fatigue

8

what antibodies can be tested for when looking for myasthenia gravis?

anti acetylcholine receptor (85%)

anti MUSK (7%)

around 7 % no antibody is found (suggest another unfound)

9

what is the edrophonium test and how does it work?

edrophonium is an acetly choline-esterase inhibitor

it can temporarily reverse myasthenia gravis signs

administed IV and in a double Blind fashion

10

what are the typical EMG features seen in myasthenia gravis?

decremental loss of the compound muscle action potential (CMAP)

and on a single fibre EMG, the phenomenon of jitter and block is seen

11

what is jitter and block?

jitter the phenomeneon of a delay between the firing of muscles more distal to the nerve.

block is when the more distal muscle fibres never actually fire.

12

what are the three treatment mechanisms for myasthenia gravis

increasing the synaptic cleft acetylcholine concentration

avoiding immune mediated end plate damage

removing antibodies and their production (plasmapherisis)

13

what two drugs can be used to test for Myasthenia Gravis

Neostigmine
pyridostigmine

block the breadown of acetylcholine by acetylcholine esterase in the synapse hence increasing the amount of acetylcholine available for the receptor

not used for treatment as they have cardiac risks

14

what treatments are used for myastenia gravis

steroids

azathioprine
methotrexate
cyclosporin
cyclophosphamide
rituximad

plasmaphoresis ( in severe cases)