Anti-Muscle-Specific Kinase (MuSK) Antibody-Positive Myasthenia Gravis Presenting With Dyspnea in an Elderly Woman: A Case Report

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.