Clinical case

A 24-year-old man of Nigerian heritage presented to the emergency department with a 1-day history of acute, ascending limb weakness. This had begun in both feet and ascended to the thighs, predominantly affecting the knees. He had a 1-day history of palpitation and a 2-day prodromal history of myalgia, cramps and stiffness involving the proximal lower limbs. There had been no recent trauma or infective symptoms, and no recent period of intense exercise, strenuous activity, heavy alcohol consumption or history of myoglobinuria. He studied from home and had been sedentary for most days before admission. There was no relevant family history. He was under the care of the mental health team for a previous episode of psychosis 6 years before, for which he was prescribed aripiprazole but had been non-compliant.

On examination, he was alert and very anxious, but with no respiratory distress and not requiring oxygen therapy. His heart rate was 180 beats/min and blood pressure was 180/85 mm Hg. He was afebrile. An ECG showed atrial fibrillation with fast ventricular response, presumed to be new. There was no cranial nerve disturbance, and specifically no exophthalmos, and with normal pharyngeal muscles and tongue movements. There was no muscle atrophy or hypertrophy. His tone was reduced in all limbs. He could not move his neck. His strength was grade 1 proximally and grade 3 distally in both upper and lower limbs. The weakness was not fatiguable. He was globally areflexic. There were no sensory deficits or cerebellar signs.

An hour into admission, his condition progressed rapidly. He developed worsening cardiac dysrhythmia and unstable blood pressure, unresponsive to beta blockers, amiodarone and inotropes. He reported an odd sensation in his throat and his cough appeared weak. His forced vital capacity was not measured but there were concerns that his airway was threatened …