Myasthenia Gravis Flashcards
What is it?
a post-synaptic NMJ disorder characterized by progressive muscular weakness and fatiguability on exertion
What is MG associated with?
thymus tumor, thyrotoxicosis, RA, and Lupus
MG is typically seen in
females 20-30 yo
equally in men and women 60-80 yo
what is the primary impairment reported by patients
fatigue or weakness with sustained activity
MG presentation
- diplopia (90% of cases involve extra ocular mm)
- ptosis (pupillary reflex not affected)
- dysarthria
- LE weakness
- generalized weakness
- dysphagia
- sustained muscular effort impaired, while brief effort is normal
- reflexes normal and little atrophy
may be fatal
pts die of respiratory infection or other complications
4 types
- ocular
- mild generalized
- severe generalized
- crisis
ocular myasthenia
confined to extra ocular muscles
mild generalized myasthenia/ severe generalized
involves bulbar and proximal limb-girdle muscles
crisis
with respiratory failure
- medical emergency
examining cranial nerves
examine for diplopia and ptosis; progressive dysarthria or nasal speech, difficulties in chewing and swallowing; difficulty in facial expression, drooping facial muscles
ice pack test
a positive test is decreased ptosis after a 2 min application of an ice pack to the affected eyelif
muscle strength
proximal muscles are more involves than distal
nerve conduction studies
show abnormal and decremented responses to repetitive nerve stimulation at baseline and 2-4 mins after isometric exercise
medical intervention
- Cholinesterase inhibitor: block breakdown of ach
- corticosteroids
- plasmapheresis
- thymectomy
