1. Department of Neurosurgery, The Walton Centre for Neurology & Neurosurgery NHS Foundation Trust, Liverpool, UK
2. School of Medicine, University of Liverpool, Liverpool, UK
3. Institute of Ageing and Chronic disease, University of Liverpool, Liverpool, UK
4. Department of Otolaryngology and Head & Neck Surgery, Aintree University Hospitals NHS Foundation Trust, Longmoor Lane, Liverpool, UK
5. Clatterbridge Cancer Centre NHS Foundation Trust, Wirral, UK
6. Department of Neurosurgery, Beaumont Hospital, Dublin 9, Ireland