1 Royal National Throat, Nose and Ear Hospital, University College London Hospitals NHS Trust, 330 Grays Inn Road, WC1X 8DA, London, UK. bhik.kotecha@uclh.nhs.uk.
2 Royal National Throat, Nose and Ear Hospital, University College London Hospitals NHS Trust, 330 Grays Inn Road, WC1X 8DA, London, UK.