S C Leong1, T H Lesser1, P Andrews2, S R Saeed2,3. 1. The Skull Base Unit, Department of Otorhinolaryngology - Head and Neck Surgery, Aintree University Hospital, Liverpool, UK. 2. Department of Otorhinolaryngology - Head and Neck Surgery, The Royal National Throat, Nose & Ear Hospital, London, UK. 3. The Ear Institute, Faculty of Brain Sciences, University College London, London, UK.