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Background Myasthenia gravis (MG) typically presents with fatigable muscle weakness, often involving ocular and bulbar muscles. Isolated respiratory failure is a unique and rare presentation of MuSK antibody-positive disease.Case Presentation A previously healthy 19-year-old male presented to the ED with a 3-day history of dyspnoea and headache. Initial examination revealed grade 5/5 global strength, brisk reflexes, and normal ocular and bulbar function. He rapidly became obtunded with severe bradypnoea and type 2 respiratory failure (pH 7.14, pCO2 122mmHg, HCO3 41mmol/L) requiring emergency intubation. Initial workup including biochemistry, autoimmune panels, cerebrospinal fluid analysis, chest imaging, and MRI brain were unremarkable. The provisional hypothesis was a central hypoventilation syndrome. Only on day 6 of his ICU admission did he develop ptosis, and complex ophthalmoplegia. A positive neostigmine test suggested neuromuscular junction dysfunction. Treatment with IVIG and prednisone were initiated, resulting in clinical improvement. MuSK antibodies returned positive three weeks later. Despite initial improvement, the patient experienced a further respiratory crisis prior to planned rituximab therapy and after further admission for BiPAP, was commenced on ongoing nocturnal non-invasive ventilation. At 6-week follow-up, the patient achieved complete clinical remission with a myasthenia composite score of 0.Discussion This case highlights the importance of considering neuromuscular junction disorders in unexplained respiratory failure, even in the absence of typical myasthenic symptoms. MuSK-positive MG can present atypically with isolated respiratory failure and carries a higher risk of respiratory crises compared to other MG subtypes. Early recognition, supportive therapy and appropriate immunotherapy are crucial for optimal outcomes.