Myasenthis Gravis

Question 1

disorder of the neuromuscular junction resulting in a pure motor syndrome characterized by weakness and fatigue particularly of the extraocular, pharyngeal, facial, cervical, proximal limb and respiratory musculature

Answer 1

Myasenthia Gravis

Question 2

predominant age?

Answer 2

20-40 but at any age

Question 3

incidence peaks in females when and males when?

Answer 3

females: 3rd decade
males: 5th/6th decade

Question 4

humoral immune mediated injury of the postsynaptic ______ junction ______receptors

Answer 4

neuromuscular

acetylcholine

Question 5

MC associated condition?

Answer 5

thymoma

also thymic hyperplasia, thyrotoxicosis and other AI dx

Question 6

signs and symptoms?

Answer 6

PTOSIS 
diplopia
facial weakness 
fatigue on chewing 
dysphagia 
dysarthria 
dysphonia
neck weakness
proximal limb/respiratory/generalized weakness

Question 7

Ice pak test?

Answer 7

ice against eyelids for 2 min, “+” is improvement of Ptosis

Question 8

motor nerve conduction and sensory nerve conduction velocity should be what?

Answer 8

normal

Question 9

repetitive nerve stimulation: decremental response at 3 HZ, this is seen more frequently where?

Answer 9

proximal, cervical or facial muscles

Question 10

in the repetitive nerve stimulation, the decrement is less pronounced when and more pronounced when?

Answer 10

30 seconds

120 seconds

Question 11

Edrophonium (enlon,tensilon test): *****

Answer 11

initial dose 2 mg, then 3mg after 30 seconds, then 5mg after 40 seconds (10 mg total)

”+” is improvement of strength of striated muscle within 30 seconds

Question 12

Acetylcholine receptor antibody (AChR):

list the positive % values:

generalized myanthenia:

ocular myasthenia:

myasthenia and thymoma:

congential myasthenia:

Answer 12

80%
50%
100%
0%

(% does not mean severity)

Question 13

check (MuSK) muscle specific tyrosine kinase ab:

what % of NEGATIVE AChR pts have abs to MuSK?

Answer 13

40-50%

Question 14

imagine tests:

Answer 14

chest CT (to see thymoma)

Question 15

pathological findings:

muscle electron microscopy: receptor infolding and the tips of the folds are what? synaptic clefts are what?

Answer 15

lost

widened

Question 16

Pathological findings:

immunofluorsecence: what are on receptor membranes?

Answer 16

IgG abs

complement

Question 17

meds to avoid: (8)

Answer 17

aminoglcosides 
magnesium 
penicillinamine 
interferon alpha 
beta blockers 
quinidine 
quinine
procainamide

Question 18

tx: 3 basic approaches

symptomatic, immunosuppressive, supportive

symtomatic…

Answer 18

acetylcholinesteraase inhibitors (“stigmine”

Question 19

does symptomatic therapy stop the ongoing immunologically mediated damage to muscle receptor?

what happens in an overdose?

Answer 19

no

cholinergic crisis (excessive secretions, D, bradycardia)

Question 20

immunosuppressive therapy: thymectomy, steriods, plasmapheresis, immunosuppressive drugs like what?

Answer 20

mycophenolate!!

azathioprine, cyclophosphamide, cyclosporine, IV human gamma globulin

Question 21

pyridostigmine bromide: what do we have to do to the dose?

Answer 21

titrate dose

Question 22

Neostigmine methylsulfate:

what do we have to do to the dose?

would use this when?

Answer 22

titrate

thymectomy, plasmaphoresis

Question 23

what steroid can we use?

Answer 23

prednisone, must taper