Anti-MuSK myasthenia after allogeneic hematopoietic stem cell transplantation in acute myeloid leukemia

Abstract

Anti-MuSK myasthenia is a chronic autoimmune disease caused by violation of the function of the agrin-MuSK-Lrp4 complex, accompanied by the development of pathological muscle fatigue and often muscle atrophy. The disease can be a primary, as well as a complication of immunosuppressive therapy and hematopoietic stem cell transplantation. We present a case of anti-MUSK myasthenia gravis that developed after allogeneic HSCT due to acute myeloid leukemia in a 44-year-old patient (born in 1975). A distinctive feature of the case was a generalized injury, including not only extraocular, but also paravertebral muscles, dropped head syndrome in the evening. In addition, laboratory, electroneuromyographic and neuroimaging (MRI of muscles, MR-spectroscopy) data indicating the neurogenic reversible nature of changes in the involved musculature are presented.Results. This study presents MRI and EMG signs of neurogenic damage of axial musculature in a patient with weakness and swelling of the paravertebral muscles (edematous changes according to STIR, corresponding to MR signs of early functional denervation) for a period of 2–4 months, due to anti-MUSK myasthenia gravis. Clinical manifestations, as well as edematous neurogenic changes in the paravertebral muscles, regressed after pathogenetic therapy. Conclusion. The article presents up-to-date data on the clinical and instrumental characteristics of myasthenia gravis. The considered clinical example confirms the presence of neurogenic changes at an early stage of anti-MUSK myasthenia gravis and indicates the need for immediate initiation of pathogenetic therapy to avoid the development of atrophy and fatty infiltration of muscles.