Myasthenic crisis is usually associated with infection and is characterized by respiratory failure requiring invasive or noninvasive mechanical ventilation. This chapter presents a case study of a 46-year-old African-American female with a 9-year history of myasthenia gravis (MG) who developed a progressive bilateral lower extremity numbness and pain from a bulging lumbar disc. Myasthenic crises are often precipitated by pulmonary infections and result in respiratory failure requiring mechanical ventilation. Potential cardiac manifestations of MG include focal myocarditis, atrial fibrillation, atrioventricular conduction delay, and left ventricular diastolic dysfunction. In the approach to the patient with myasthenic crisis, (1) the diagnosis of MG should be confirmed; (2) respiratory failure should be evaluated and treated in the intensive care unit (ICU), while potential precipitating factors are identified and managed; (3) immunomodulatory treatment should be initiated; and (4) complications should be avoided or managed promptly.