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7/27/2019 1.b.miyasteniagravis 02
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MYASTENA GRAVS(Myasthenia gravis)Anwar Wardy*
(07.30-08.20)anwar wardy.FKK-UMJNeurologist, DFM
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Dokter dengan Tingkat kemampuan3b.
Mampu membuat diagnosis klinik berdasarkanpemeriksaan fisik dan penunjang lain: Lab
sederhana dan X-rays.
Mampu memutuskan diagnoses danmemutuskan terapi pendahuluan, serta
merujuk ke spesialis yang relevan kasus gawatdarurat.
anwar wardy wfkk umj
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Myasthenia Gravis
Autoimmune
Incidence < 1/100,000
Prevalence 1/7500
Females 20s - 30s
Males 70s - 80s
anwar wardy.FKK-UMJNeurologist, DFM
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Myasthenia Gravis
Fatigue, Weakness
Proximal Muscles
Bulbar musclesptosis, diplopia, weakness, dysphagia, dysarthria
worst as day progresses, prolonged activity (reading,chewing)
anwar wardy.FKK-UMJNeurologist, DFM
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Myasthenia Gravis - Diagnosis
Edrophonium
Antibodies
EMG
anwar wardy.FKK-UMJNeurologist, DFM
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Myasthenic Crisis
Respiratory failure due to severity of symptoms
FVC < 1L - consider intubation
Ensure the known myasthenic patient receives their regulardosing while in the ED (ie. Pyridostigmine 60mg q4h)
anwar wardy.FKK-UMJNeurologist, DFM
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Myasthenic Crisis VersusCholinergic Crisis
Myasthenic : inadequate drug delivery
Cholinergic : excessive drug delivery
anwar wardy.FKK-UMJNeurologist, DFM
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Myasthenic Crisis VersusCholinergic Crisis
Edrophonium (Tensilon) 1-2mg IV (1/10thdose)
resolution (total/partial) suggests myastheniccrisis
give rest of dose (8mg) for full effect
follow with neostigmine IM/SC 0.5 - 2mg
doses q4h
anwar wardy.FKK-UMJNeurologist, DFM
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Myasthenic Crisis VersusCholinergic Crisis
Exacerbation, fasiculations, respiratorydepression suggests cholinergic crisis
beware possible need for intubation at thispoint
further Tensilon contraindicated effects
wear off quickly
anwar wardy.FKK-UMJNeurologist, DFM
7/27/2019 1.b.miyasteniagravis 02
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Tensilon
Cholinergic (muscarinic) agent
Atropine to treat bradycardia, AV block, cardiac
arrestMuscle paralysis (nicotinic) atropine not effective
Unpleasant side effects
anwar wardy.FKK-UMJNeurologist, DFM
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Treatment of MG
Neostigmine / Physostigmine
Plasmapheresis
Steroids
Thymectomy
anwar wardy.FKK-UMJNeurologist, DFM
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Myasthenia gravisneuromuscular junction
disorder
weakness and fatigue of
skeletal muscles
anwar wardy.FKK-UMJNeurologist, DFM
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Normal and myasthenicneuromuscular junctions
anwar wardy.FKK-UMJNeurologist, DFM
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Immunopathogenesis of MGantigen: acetylcholine receptor
antibody: IgG to Ach receptor (80% of cases)
passive transfer: injection of patients IgG into mice
reproduces disease
immunization with antigen reproduces disease
good correlation between antibody levels and clinical
disability in the same patient
anwar wardy.FKK-UMJNeurologist, DFM
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Origin of the autoimmune
response in myasthenia gravis
antibodies produced by B cells
T cell clones reactive to Ach receptors in blood and
thymuses of MG patients
75% of patients have thymus hyperplasia or thymoma
thymectomy improves clinical condition
thymus gland contains muscle-like cells with surface
Ach receptors
anwar wardy.FKK-UMJNeurologist, DFM
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MuSK antibodies in MG((Myastheniagravis)
70% of patients with former seronegative MG
antibody to the muscle specific tyrosin kinase (agrinreceptor)
Agrin mediates clustering of Ach receptors during synapse
formation
anwar wardy.FKK-UMJNeurologist, DFM
MuSK
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Acquired presynapticNMJ disorders
LEMS: idiopathic or paraneoplastic antibodies to
voltage-gated calcium channels on the presynaptic
membrane
Botulism: toxin inhibits release of Ach
from presynaptic vesicles
therapeutic use for muscle
overactivity disorders
anwar wardy.FKK-UMJNeurologist, DFM
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Congenital myasthenic disorders
anwar wardy.FKK-UMJNeurologist, DFM
Paucity of synaptic vesicles
Choline acetyltransferase def
Ach-esterase deficiency
Ach receptor deficiency
Rapsyn deficiency
presynaptic
synaptic
post-synaptic
basal lamina
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MG istirahat
anwar wardy.FKK-UMJNeurologist, DFM
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EMG
Normal
anormal
anwar wardy.FKK-UMJ Neurologist, DFM
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Wassalam, Wr,Wbr
Reference: Text Book of Neurology Gilroy. 2005
Thank U
anwar wardy.FKK-UMJ Neurologist, DFM
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