In addition to pyridostigmine, immunosuppression with glucocorticoids or azathioprine is indicated for acute myasthenic flares. Second-line immunosuppressive agents include methotrexate and cyclophosphamide. For patients experiencing myasthenic crisis, intravenous immunoglobulin or plasmapheresis are indicated to prevent respiratory collapse due to their rapid onset. Thymectomy is recommended in patients with evidence of thymoma, seronegative disease, or anti-nicotinic-AcH subtype of disease if presentation occurs between the ages of 15 and 50.⁶

The initial diagnostic workup for patients with MG symptoms should include a complete neurological exam. Additionally, cranial imaging should be used to rule out stroke or intracranial mass, which may present with similar symptoms. Patients should also undergo CT or MR imaging of the thymus, as well as measurement of thyroid-stimulating hormone to investigate concomitant autoimmune thyroid disease. Differential diagnosis may include disorders of the neuromuscular junction or the peripheral nervous system, such as Lambert-Eaton Syndrome, botulism, Horner Syndrome, neuromyotonia, or Guillain-Barré Syndrome. Diagnosis may be confirmed by nerve conduction study or by the presence of anti-AcH or anti-MuSK antibodies, although a small percentage of patients are seronegative.⁸ Historically, checking for symptom improvement in response to intravenous edrophonium, a short-acting acetylcholinesterase inhibitor, was seen as the gold standard diagnostic test for MG, but this has since been supplanted by serologic and nerve conduction studies due to the concern for serious side effects, including bradycardia and bronchospasm.¹ The ice pack test has proven to be an effective initial method of diagnosis for ocular MG. When used to detect MG in patients presenting with diplopia, ptosis, or both, the ice pack test has been reported to demonstrate a sensitivity of 76.9 percent and a specificity of 98.3 percent.⁹ The authors of this study found the test to remain highly specific, even in patients with co-existing thyroid dysfunction.

Conclusion

Patients presenting with their first MG flare require prompt diagnosis and treatment to prevent progression of symptoms. The initial diagnosis of MG is largely clinical. Results from anti-AcH and Anti-MuSK serologic testing may take several days, and treatment should not be withheld for confirmatory testing. In this patient’s case, ice pack testing could have easily been done at the first ED. A correct diagnosis was made quickly at our facility, which allowed for rapid admission and initiation of treatment. With maintenance immunosuppression, the prognosis of individuals with ocular MG is good; most live a normal life expectancy with minimal disability.⁸

Dr. Cray is a first-year emergency medicine resident at Summa Health in Akron, Ohio, with interests in EMS and wilderness medicine.