Case summaryA 10-year-old boy presented with severe progressive generalised weakness on a background of 3 days of diarrhoea and vomiting. Vital signs were normal. Peripheral neurological examination revealed grade 1-2 power in all limbs, hypotonia and hyporeflexia. Sensation was fully intact. Cranial nerve examination and speech were normal. The ECG (figure 1) and initial venous blood gas (figure 2) are shown.edpract;107/1/21/F1F1F1Figure 1ECG.edpract;107/1/21/F2F2F2Figure 2Venous blood gas. QUESTION 1: What abnormalities are present on the ECG?Peaked T waves, prolonged PR segment and loss of P waves?Shortening of the QT interval and Osborn waves (J waves)?T wave flattening/inversion, prominent U waves and long QU interval?Prolonged QT interval with multiple atrial and ventricular ectopics? QUESTION 2: How would you manage this patient's hypokalaemia? QUESTION 3: What is the likely diagnosis?Conversion disorder.Myasthenia gravis.Periodic paralysis.Guillain-Barré syndrome.Botulism. QUESTION 4: What interventions can be considered for long-term treatment of this condition? .