1 Neurovascular Research Laboratory, University of South Wales, Glamorgan, Pontypridd, CF37 4AT, UK. Electronic address: damian.bailey@southwales.ac.uk.
2 Welsh Institute of Chiropractic, Faculty of Life Sciences and Education, University of South Wales, Glamorgan, Pontypridd, CF37 4AT, UK.
3 Department of Neurology, University Hospital of Wales, Heath Park, Cardiff, UK.