title: Corrigendum.
authors.affiliation: Department of Clinical Neurosciences, Division of Neurosurgery, University of Cambridge, Box 167, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK.
authors.forename: Colin
authors.initials: C
authors.lastname: Watts
authors.affiliation: John van Geest Centre for Brain Repair, Department of Clinical, Neurosciences, University of Cambridge, Cambridge, CB2 0PY, UK.
authors.forename: Sara G M
authors.initials: SG
authors.lastname: Piccirillo