A 29-year-old man presents with progressive ascending weakness over 3 days following a diarrhoeal illness 2 weeks ago. Reflexes are absent in all limbs and there is mild facial weakness. What is the most appropriate next investigation?ANerve conduction studies and urgent admission for monitoringBMRI spine with contrast onlyCLumbar puncture in the communityDOutpatient neurology review in 4 weeksEStart high-dose oral steroids without investigationCheck my answer