Myasthenia Gravis, Guillain–Barré Syndrome, or Both?

Myasthenia gravis (MG) and Guillain-Barré syndrome (GBS) are autoimmune disorders that may cause weakness in the extremities. The coexistence of MG and GBS in the same patient has rarely been reported previously. A 52-year-old male presenting with ptosis of the left eye that worsened with fatigue, especially toward evening, was evaluated in our outpatient department. His acetylcholine receptor antibody results were positive, supporting the diagnosis of MG. His medical history revealed a post-infectious acute onset of weakness in four extremities, difficulty in swallowing and respiratory failure, which was compatible with a myasthenic crisis; however, his nerve conduction studies and albuminocytologic dissociation at the time were compatible with GBS. With this case report, we aimed to mention this rare coincidental state, discuss possible diagnoses and review all other similar cases in the literature with their main features.