49 Myasthenia Gravis Flashcards
Thymic tumors occur in what percentage?
10-15%
Usual sites of metastasis of thymomas
Lungs and Liver
Histologic characteristic of thymoma
Hyperplasia of the medulla characterized by lymphoid follicles with active germinal centers (p1475)
A second period of danger in progressive caes is from what year of onset?
4-7yrs of onset
Grading Classification of MG
Osserman
Most frequently affected trunk muscle in MG
Erector spinae
Prevalence of MG
43-84 per million persons (Epidemiology p.1473)
Peak age of first symptoms
20-30 women, 50-60 men
The main ultrastrucrural alterations occur in the?
Motor endplate
Changes in the motor endplate
Simplification in the surface area of the postsynaptic membrane (sparse,shallow, abnormally wide or absent synaptic cleft) and a widening of the synaptic cleft
Defect in myasthenia gravis?
Marked reduction in the number of ACh receptors of the postsyanptic membrane of the NMJ
Rapid reduction in the amplitude of compound muscle action potentials during a series of repetitive stimulation of a peripheral nerve at a rate of 3 per second
Decrementing response
Technique that demonstrated an inconstancy of the normally invariant interval between the firing of muscle fibers connected to the same motor unit
Single fiber EMG
A nonneoplastic lymphofollicular hyperplasia of the thymic medulla occurs in
65%
anticholinesterase inhibitors
Neostigmine
Endrophonium
This enzyme plays a role in supporting the normal structure of the postsynaptic membrane and in the arrangement of AChR but its main function may be in developmental synaptic differentiation.
IgG antibodies against intracellular muscle specific kinase (MuSK)
There is an increased representation of these Haplotypes in MG
HLA-B8 and DR3 (p1474)
Onset before age 40,no thymoma-female.
which antigens are involved?
HLA A1, B8, DRW3 Antigens (p1464)
onset after 40, no thymoma- male preponderance
which antigens are involved?
HLA A3, B7, DRW2, Low AChR ani body titer
