Myasthenia gravis resident survival guide

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Myasthenia gravis Resident Survival Guide Microchapters

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: , Moises Romo, M.D., Fahimeh Shojaei, M.D.

Synonyms and keywords:Myasthenia gravis management, Myasthenia gravis workup, Myasthenia gravis approach, approach to Myasthenia gravis, Myasthenia gravis treatment


Myasthenia gravis is a neuromuscular disease leading to fluctuating muscle weakness and fatiguability. It is an autoimmune disorder, in which weakness is caused by circulating antibodies that block acetylcholine receptors at the post-synaptic neuromuscular junction, inhibiting the stimulative effect of the neurotransmitter acetylcholine. The diagnosis is maily clinical, although ordering acetylcholine autoantibodies may sometimes be necessary. Physical examination of patients with myasthenia gravis is usually remarkable for: downward lip corners and depress face, asymmetrical ptosis, incomplete eye closure, Cogan's lid twitch, peek sign, weakness of oropharyngeal muscles, respiratory muscle weakness, dropped head syndrome, and proximal muscle weakness. Thoracic immaging may reveal a mediastinal mass (thymoma). Edrophonium test is used in patients with obvious ptosis or ophthalmoparesis. Myasthenia is treated medically with cholinesterase inhibitors or immunosuppressants and in selected cases with thymectomy.


Life Threatening Causes

Life-threatening causes include conditions that may result in death or permanent disability within 24 hours if left untreated.

  • Myasthenia gravis is not a life-threatening condition that may result in death or permanent disability within 24 hours if left untreated.

Common Causes


Shown below is an algorithm summarizing the diagnosis of Generalized weakness according to the American Academy of Neurology guidelines:

Generalized weakness symptoms
True motor weakness?
Evaluate for causes of fatigue or muscle pain
Myasthenia Gravis
Lambert-Eaton syndrome
Periodic paralysis
Metabolic myopathy
•Inclusion body myopathy
Amyotrophic lateral sclerosis
Multifocal motor neuropathy
Congenital myopathy
Congenital dystrophy
•Kearns-sayre syndrome
•Oculopharyngeal dystrophy
Ocular dystrophy
•Fascioscapulohumeral dystrophy
Myotonic dystrophy
Upper extremities
•Emery-Dreiffus dystrophy
•Hereditary distal myopathy
Lower extremities
Duchenne's muscular dystrophy
Becker's muscular dystrophy
Spinal muscular atrophy
•Limb girdle dystrophy


Shown below is an algorithm summarizing the treatment of myasthenia gravis according the the European Academy of Neurology guidelines:[18]

Myasthenia gravis
Considere early thymectomy
Ocular; mild symptoms
Moderate to severe symptoms
Impedeing myasthenic crisis
Start AChEI
Monitor FVC and clinically
Start AChEI (most patients will requiere steroids early)
Monitor close in HDU/ITU
Plasma exchange (5 cycles
IVIg 0.4g/kg/d x 5 days)
No improvement
Start steroids
Target dose ocular- 0.5mg/kg/day
Target dose generalized- 1mg/kg/day
Target dose achieved or in remission at a small dose for 2-3 months
Reduce prednisolone gradually<be> Taper by 10mg/month until on 30 mg OD; then by 5mg/month until on 15 mg OD; then by 1-2mg/month to the smallest possible dose
Unable to reduce prednisolone or frequent relapses
Start steroids-sparing drugs: azathioprine (check TPMT), mycophenolate or methotrexate
Unable to tolerate
Consider cyclosporin, tacrolimus, cyclophosphamide or rituximab
Treat as refractory myasthenia gravis if no improvement or undesirable side effects despite adequate dose and duration of 2 steroid-sparing agents




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