When a patient comes to the emergency department with decreased sensorium, a thorough examination should be done in order to arrive at a proper diagnosis and treatment. This includes evaluation of cerebral vascular disorders like haemorrhage and infarct; metabolic and electrolyte abnormalities like hypoglycaemia, hyponatremia, hypercalcaemia, uraemic and hepatic encephalopathy; hypoxia; carbon dioxide narcosis; and carbon monoxide poisoning. We recently encountered an elderly male patient who came to the emergency department with unconsciousness and was found to have a raised carbon dioxide level in the blood and, subsequently, a high level of anti-acetylcholine receptor antibodies. The patient was treated in line for myasthenia gravis, following which he made a complete recovery.

Learning Points
• Myasthenia Gravis can present with decreased sensorium as an initial presentation.
• Myasthenia Gravis should be considered in any patient with unexplained difficulty weaning from ventilator support.
• High degree of suspicion and early diagnosis are required for a better outcome. Myasthenia Gravis, decreased sensorium, carbon dioxide narcosis.