Myasthenic CrisisAdded by Matthew M Hastings , last edited by Matthew M Hastings on Feb 01, 2012

Monitoring

• IF IN ANY DOUBT, GO SEE THE PATIENT!!!

• Monitor respiratory parameters every few hours.
  • NIF (it should be more negative than -30 in general)
  • Vital cap (concerning when <10-12 mg/kg)
  • Other ways to assess respiratory status
    • Quality of cough
    • Ability to count out loud in one breath
  • These are partially driven by patient effort, so use these in combination. No single number or sign can substitute for a good exam and your general impression.

Time to move to the ICU?

• If you are worried about the patient's respiratory status at all, get them to the ICU. Myasthenia gravis patients can crash quickly and without much warning!

• Do NOT rely on the O2 sat or ABG to predict a crash. This may not change until it is too late!

• Consider BiPAP in ICU to try to avoid need for intubation.
  

  Work-up

• Perform infectious work-up for every myasthenic crisis with:
  • Blood cultures
  • Urine cultures
  • CXR
• Consider non-contrast chest CT for thymoma

  Treatment

• Acetylcholinesterase Inhibitors
  • Pyridostigmine (Mestinon and Mestinon Timespan (extended release))
    • Symptomatic treatment only.
    • Unnecessary in intubated patients; in fact, increase secretions.
    • You can provide mestinon, but not mestinon timespan, via dobhoff
    • Conversion of PO pyridostigmine:IV pyridostigmine is 30:1
• Glycopyrrolate (Robinul) to decrease secretions
• Steroids
  • High dose steroids can initially cause worsening! But later can help suppress immune response.
  • If already intubated, start high dose steroids (prednisone 60 mg PO qAM or solu-medrol 500 mg IV qAM)
• IVIg
  • Used acutely in crisis or for maintenance
  • Typical load for MG
    • If old, renal insufficiency, or severe cardiac disease & hypertension: 0.5 gram/kg over 4 days
    • If young and no renal or cardiac disease: 1 gm/kg daily x 2 days
  • If the patient has known renal disease and you must use IVIg:
    • Use the lysine based Gammagard formulation
    • Avoid concurrent use of nephrotoxic medications
    • Avoid concurrent IV contrast
    • Aggressively hydrate the patient during IVIg treatments
• Plasmapheresis
  • Used acutely in crisis or for maintenance
  • QOD x 5 treatments, and then reevaluate for need for further series
  • See AIDP section for more information on apheresis.
• Other immunosuppressants for maintenance
  • Mycofenolate mofetil (Cellcept)
  • Azathioprine (Imuran)