myasthenia gravis

Question 1

in which muscles there is weakness in MG?

Answer 1

proximal muscles of limb, ocular muscles, bulbar muscles

Question 2

age and sex distribution of MG?

Answer 2

more common in women, peak incidence in 20-30 in women and in men 50

Question 3

pathogenesis?

Answer 3

igG antibodies against acteylcholine receptor at neuromuscular junction. receptor number is decrease due to antibody mediated autoimmune attack

Question 4

association with other diseases?

Answer 4

sle, RA, thyroid gland, pernicious anemia and treatment with penecillamine, thymic hyperplasia is found in 70% of patient

Question 5

clinical features?

Answer 5

relapse may be precipitated by emotional disturbance, infection, pregnancy, aminoglycosides, magnesium sulphate enema, diplopia, ptosis, weakness of lid, weakness in palate, tongue, pharynx, muscle of shoulder gridle affeted more, tendon reflex are normal,

Question 6

investigation?

Answer 6

achR antibodies in 90% cases, tensilon test, nerve stimulation test, chest xray Ct, MRI and tests for other autoimmune disease.

Question 7

tensilon test?

Answer 7

edorphonium (anticholinesterase) 2mg is given iv then weakness improve then test is positive

Question 8

D/D?

Answer 8

botulism, lambert eaten myasthenia syndrome, hyperthyroidism, intracranial mass, progressive external opthalmoplegia, excessive penecillamine

Question 9

treatment?

Answer 9

to maximize the activity of actylecholine or reduce the autoimmune reaction
pyridostigmine 30-120mg 6 hourly(side effect diarrhea, nausea, salivation, cholinergic crisis due to depolarization block.
thymectomy
steriods during hospital admission
azathioprine help to reduce the dose of steriods
cyclosporin has rapid effect than azathioprine
immunoglobulins and plasmapharesis in cholinergic crisis, or for pre-operative purpose.