Diana Y Wei1, Mike Bradley2, Zsolt Orosz2, James C Stevens2. 1. From the Departments of Neurology (D.Y.W., J.C.S.) and Radiology (M.B.), North Bristol NHS Trust; and Department of Histopathology (Z.O.), Oxford University Hospitals, UK. dianawei@doctors.org.uk. 2. From the Departments of Neurology (D.Y.W., J.C.S.) and Radiology (M.B.), North Bristol NHS Trust; and Department of Histopathology (Z.O.), Oxford University Hospitals, UK.