Shiozumi Tadaharu, Okada Nobunaga, Matsuyama Tasuku, Yamahata Yoshihiro, Ohta Bon
Department of Emergency Medicine, Kyoto Prefectural University of Medicine, Kyoto, JPN.
Department of Emergency Medicine, Japanese Red Cross Society Kyoto Daiichi Hospital, Kyoto, JPN.
Cureus. 2023 Dec 13;15(12):e50480. doi: 10.7759/cureus.50480. eCollection 2023 Dec.
Myasthenia gravis (MG) is an autoimmune disease and represents one of the most common disorders associated with neuromuscular transmission defects. Within MG, the anti-muscle-specific kinase antibody-positive subtype (MuSK-positive MG) is rare. While it shares similarities with the common form of MG by presenting with ocular weakness, MuSK-positive MG typically presents with more atypical symptoms. Although MuSK-positive MG can lead to type 2 respiratory failure due to respiratory weakness, there have been limited reports where initial presentation involves only respiratory compromise. This study details a case of MuSK-positive MG presenting dyspnea. An 84-year-old female presented to the emergency department due to a three-day history of progressive respiratory distress, characterized by increased respiratory effort and shallow breathing, resulting in a diagnosis of type 2 respiratory failure. Despite the absence of neurological abnormalities, she tested positive for anti-muscle-specific kinase antibodies, confirming a diagnosis of MuSK-positive MG. This case highlights the significance of considering MG in the context of type 2 respiratory failure, even in the absence of typical neurological symptoms, especially in elderly patients.
重症肌无力（MG）是一种自身免疫性疾病，是与神经肌肉传递缺陷相关的最常见疾病之一。在重症肌无力中，抗肌肉特异性激酶抗体阳性亚型（MuSK阳性MG）较为罕见。虽然它与常见形式的重症肌无力有相似之处，表现为眼部无力，但MuSK阳性MG通常表现出更不典型的症状。尽管MuSK阳性MG可因呼吸肌无力导致Ⅱ型呼吸衰竭，但仅有有限的报告显示初始表现仅为呼吸功能不全。本研究详细介绍了一例以呼吸困难为表现的MuSK阳性MG病例。一名84岁女性因进行性呼吸窘迫3天就诊于急诊科，其特征为呼吸费力增加和呼吸浅快，最终诊断为Ⅱ型呼吸衰竭。尽管没有神经学异常，但她的抗肌肉特异性激酶抗体检测呈阳性，确诊为MuSK阳性MG。该病例强调了即使在没有典型神经症状的情况下，尤其是在老年患者中，在Ⅱ型呼吸衰竭背景下考虑重症肌无力的重要性。
