P-PN015. Rituximab therapy in post thymectomy refractory myasthenia gravis: A case report

Abstract

Introduction . Myasthenia gravis (MG) is one of the autoimmune diseases caused by disruption of synaptic transmission at the neuromuscular junction. An estimated 10–20% patients with MG will still experience frequent relapses even after receiving the standard MG treatment with pyridostigmine and immunosuppressants. Rituximab can be considered as a therapeutic option in MG patients that show unsatisfactory response to standard therapy. Case report: A female patient, 31 years old, was diagnosed with myasthenia gravis in 2017, and tested positive for acetylcholine receptor antibody (AChR antibody). Upon diagnosis, her Myasthenia Gravis Composite (MGC) score was 22. She was administered with pyridostigmine 4x60 mg per oral (PO) and methylprednisolone 3x16 mg PO. She was hospitalized three times in two months due to MG relapses. In addition, the patient suffered an episode of myasthenic crisis with mechanical ventilator support one year after diagnosis, after which she had thymectomy. Post thymectomy, MGC score was 13, with medication pyridostigmine 4x60 mg PO, methylprednisolone 1x8 mg PO, and azathioprine 1x200 mg PO. The patient was still experiencing MG relapses and was admitted to hospital five times in two months. She was then administered rituximab. After rituximab therapy, her MGC score was 4, she only had relapse once within a year. Pyridostigmine 2x60 mg and methylprednisolone 1x8 mg PO were still continued. Results . A recent systematic review shows that rituximab administration gives satisfactory results in 72% of MuSK patient, 30% of AChR antibody patients, and 44% in combined both groups. In this patient, it was found that initial treatment with thymectomy surgery had unsatisfactory improvement, and relapses were remained relatively frequent. However, with additional treatment with rituximab, clinical improvement was significant. Conclusion . Rituximab is an effective therapeutic choice for refractory MG patients who fail to attain good disease control even after thymectomy.