1 Department of Neurology, St George's University Hospitals NHS Foundation Trust, London, UK.
2 Department of Neurology, Ashford St. Peter's Hospital NHS Foundation Trust, Chertsey, UK.
3 Department of Neuroradiology, Atkinson Morley Regional Neuroscience Centre, St George's University Hospitals NHS Foundation Trust, London, UK.
4 Neurosciences Research Centre, Molecular and Clinical Sciences Research Institute, St George's, University of London, Cranmer Terrace, London, SW17 0RE, UK. fmorgant@sgul.ac.uk.
5 Department of Experimental and Clinical Medicine, University of Messina, Messina, Italy. fmorgant@sgul.ac.uk.