Myasthenic Crisis Flashcards
What is a myasthenic crisis?
Myasthenic crisis is a medical emergency. It is defined as an MG exacerbation requiring mechanical ventilation.
What are the indications for mechanical ventilation?
Indications for mechanical ventilation are forced vital capacity (FVC) of 15 mL/kg or less (normal ≥60 mL/kg) and/or negative inspiratory force (NIF) of 20 cm H₂O or less (normal ≥70 cm H₂O).
Serial measurements of FVC and NIF are taken.
What causes of myasthenic crisis?
Myasthenic crisis may be provoked by infections (particularly respiratory infections), aspiration, medicines including high-dose corticosteroids, surgery, medications that are contraindicated or relatively contraindicated in MG, failure to adhere to medications, administration of immune checkpoint inhibitors as cancer therapy, or trauma.
What are the clincal features of a myasthenic crisis?
A high index of clinical suspicion is necessary for myasthenic crisis because patients may initially appear stable.
Patients who develop myasthenic crisis typically experience increasing generalized or bulbar weakness as a warning. Occasionally, a patient presents with respiratory insufficiency out of proportion to limb or bulbar weakness.
How is a myasthenic crisis treated?
Initial treatment consists of intubation and mechanical ventilation. Some patients may require non-invasive ventilation with BiPAP or full intubation and ventilation.
Medical treatment of myasthenic crisis is with immunomodulatory therapies such as IV immunoglobulins and plasma exchange.
Supportive care includes deep venous thrombosis prophylaxis; ulcer prophylaxis; adequate nutrition and hydration; and avoidance of infections and drugs that may worsen myasthenia symptoms.
