An Adopted 42-Year-Old With Slurred Speech and Memory Loss

Catherine Divingian, MD, PhD; Beena Stanley, MD; Jeffrey Jordan, MD


September 15, 2021

The patient in this case was most likely in crisis, on the basis of her use of accessory muscles to breathe and her arterial blood gas values. There are academic discussions about assessing inspiratory and expiratory functions for myasthenic crisis. Inspiratory function can be determined by the patient's vital capacity, which would be < 1 L during a crisis. Alternatively, a negative inspiratory force < 20 cm H2O could indicate a crisis. Expiratory function is evaluated by positive expiratory force, which is < 40 cm H2O.[1,11]

However, the clinical presentation is sufficient to diagnose a crisis, particularly if the patient is known to have MG. Respiratory failure is indicative of myasthenic crisis. Intubation with mechanical ventilation is often necessary because patients can easily become exhausted from the respiratory effort. The use of accessory muscles in breathing can also indicate a crisis.[1,11]

In this case, the patient was intubated owing to acute hypoxemic hypercapnic respiratory failure and inability to maintain her airway. Because she presented at a rural hospital with limited resources, she was transported via helicopter to the nearest university center with adequate medical facilities. The patient received plasma exchange therapy. A few days after treatment, she was successfully extubated and eventually discharged. She is currently taking mycophenolate mofetil, with a concomitant reduction in her prednisone dose.

It is vital to keep myasthenic crisis as a differential diagnosis in patients who may present with respiratory failure, with or without bulbar symptoms. Although this condition is rarely seen in patients without a diagnosis of MG, maintaining a high index of suspicion can be useful in determining the appropriate treatment.[1]


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