Exacerbation of myasthenia gravis following corticosteroid treatment: what is the evidence? A systematic review.

Corticosteroids (CS) are among the most widely- used immunosuppressive agents for immune-mediated conditions, including myasthenia gravis (MG). While their effectiveness in MG is documented and supported in the clinical practice over several decades, one of the main drawbacks of treatment results from the notion that MG patients may experience symptom worsening following CS treatment initiation. This may lead to the administration of lower than necessary doses of CS for the disorder, or even avoiding them altogether. As a consequence, some patients may not receive the optimal treatment to control their disease. In the present review, we analyzed 27 relevant publications and determined the prevalence of clinical exacerbation following CS treatment, its' severity and relation to the type and dose of CS. The rate of MG exacerbation is highest with the administration of cortisone, intermediate with prednisone, and lowest with methylprednisolone. High dose daily or alternate-day prednisone is associated with exacerbation more frequently than low-dose treatment, but most exacerbations are of mild to moderate severity. Other factors related to increased risk of an initial exacerbation include older age, generalized MG, bulbar symptoms, disease severity, presence of thymoma, and thymectomy. However, the current information is based mostly on heterogeneous studies of low quality, and prospective clinical trials designed to compare between the various agents and doses and assess the rate and severity of the exacerbation by a unified scale are warranted.