Objectives: To investigate the frequency, causes, and characteristic features of the course of isolated myasthenic crisis (defined as acute respiratory failure with the need for mechanical ventilation). To compare the effectiveness of three different therapeutic regimens (i.e., continuous intravenous infusion of pyridostigmine, pyridostigmine plus prednisolone, and plasma exchange) in terms of duration of ventilation and outcome of patients with myasthenic crisis.
Design: Population-based retrospective study covering the period 1970 to 1995.
Setting: University hospital, center for myasthenia gravis in Saxony, Germany.
Patients: Of 235 patients with myasthenia gravis treated at our institution, 44 patients developed a total of 63 myasthenic crises (average annual incidence 2.5%).
Interventions: Myasthenic crises were treated with pyridostigmine (n = 24), pyridostigmine plus prednisolone (n = 18), and plasma exchange (n = 21).
Measurements and main results: There were no significant differences between the three treatment groups with respect to clinical characteristics, duration of mechanical ventilation, complications, and outcome on release from intensive care and after 3 months. Eleven (17%) patients had severe cardiac arrhythmia, which ended fatally for six patients.
Conclusions: None of the therapeutic regimens applied demonstrated any advantage over the others. All three regimens used were found to be effective and should be applied depending on the circumstances prevailing. Patients with myasthenic crisis must undergo careful cardiac monitoring, and temporary pace-making should be provided where clinically indicated.