[1] Hull & East Yorkshire Hosp NHS Trust, Dept Neurol, Kingston Upon Hull, N Humberside, England
[2] Univ Hull, Hull York Med Sch, Kingston Upon Hull, N Humberside, England
[3] Keele Univ, Sch Med, Keele, Staffs, England
[4] Keele Univ, Res Inst Primary Care & Hlth Sci, Keele, Staffs, England