[1] Univ Edinburgh, Western Gen Hosp, Div Clin Neurosci, Edinburgh EH4 2XU, Midlothian, Scotland
[2] So Gen Hosp, Inst Neurol Sci, Glasgow G51 4TF, Lanark, Scotland
[3] Aberdeen Royal Infirm, Dept Neurol, Aberdeen, Scotland
[4] Fauldhouse Hlth Ctr, Edinburgh, Midlothian, Scotland
[5] Univ Dundee, Ninewells Hosp & Med Sch, Dept Neurol, Dundee DD1 9SY, Scotland