See-Saw Relationship and its Reversal after Immunotherapy in a Case of Graves' Disease with Coexisting Myasthenia Gravis.

The unique association of myasthenia gravis (MG) with Graves' disease in clinical practice emphasizes that one autoimmune disease can coexist with another or many. The relationship between these two entities has remained controversial till date. Some authors have reported a see-saw relationship between these two entities, MG waning with hyperthyroidism and waxing with treatment of hyperthyroidism. Treatment of both these disorders concurrently may be challenging at times as treatment for one entity may worsen the other. The use of beta-blockers and steroids for Graves' disease may worsen myasthenic weakness. Antithyroid drugs can worsen myasthenia probably by immunomodulatory effects. We report a case of Graves' disease coexisting with MG in a reciprocal relationship which was subsequently reversed after immunotherapy.