S K Chhetri1, S Khan2, J Nixon3. 1. From the The University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PL, UK Department of Neurology, Lancashire Teaching Hospitals NHS Foundation Trust, Preston PR2 9HT, UK chhetri@doctors.org.uk. 2. Department of Cardiology, Lancashire Teaching Hospitals NHS Foundation Trust, Preston PR2 9HT, UK. 3. Department of Neurology, Lancashire Teaching Hospitals NHS Foundation Trust, Preston PR2 9HT, UK.