A longitudinal functional MRI study of non-arteritic anterior ischaemic optic neuropathy patients
- Maria Aguirregomozcorta1,2,
- Laura Mancini1,3,
- Thomas M Jenkins1,
- Simon J Hickman4,
- Olga Ciccarelli1,
- Gordon T Plant5,
- Alan J Thompson1,
- Ahmed T Toosy1
- 1Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, University College London, London, UK
- 2Grup de Neurodegeneració i Neuroinflamació de l'Àrea de Malaltia Metabòlica-Vascular de l'Institut d'Investigació Biomèdica de Girona, Hospital Universitari Dr Josep Trueta de Girona, Girona, Spain
- 3Lysholm Department of Neuroradiology, National Hospital for Neurology and Neurosurgery, UCLH NHS Foundation Trust, London, UK
- 4Department of Neuroinflammation, UCL Institute of Neurology, University College London, London, UK
- 5Moorfields Eye Hospital, London, UK
- Correspondence to Dr A T Toosy, Department of Brain Repair and Rehabilitation, Institute of Neurology, Queen Square, London WC1N 3BG, UK;
- Received 10 September 2009
- Revised 17 December 2010
- Accepted 20 December 2010
- Published Online First 1 February 2011
Background Non-arteritic anterior ischaemic optic neuropathy (NA-AION) can cause disabling visual loss and traditionally, visual prognosis has been considered poor, although recent studies have demonstrated improvements in visual acuity in about 30% of patients over time. The aim of the study was to determine whether there was significant cortical reorganisation with functional MRI (fMRI) after acute NA-AION by comparing affected individuals with healthy controls.
Methods 9 patients with NA-AION were studied acutely and then after 1, 2, 3 and 6 months. 23 healthy volunteers underwent scanning at least twice. At each time point, patients were assessed clinically and with fMRI. For the fMRI experiments, subjects underwent monocular visual stimulation (wearing goggles with flashing LED displays).
Results When stimulating the affected eye, occipital activation was reduced in patients compared with controls. Also, within the NA-AION group, activation in the right Brodmann areas (BA) 44 and 45 was seen during the early phase of the condition. The same areas were activated within the NA-AION group several months later for fellow eye stimulation. When the NA-AION and healthy control groups were formally compared however, these areas (BA 44/45) were not significantly different. NA-AION subjects did show greater activation in visual related areas compared with controls when stimulating the fellow eye. Visual acuity was correlated with more occipital cortex activation when stimulating the affected eye.
Conclusions There is cortical re-organisation of the fMRI response in extra-visual areas, seen when both affected and fellow eyes are stimulated after NA-AION.
Funding The MS NMR Research Unit is supported by the MS Society of Great Britain and Northern Ireland. This work was undertaken at UCLH/UCL who received a proportion of funding from the Department of Health's NIHR Biomedical Research Centres funding scheme.
Competing interests None.
Ethics approval This study was conducted with the approval of the the Joint UCL/UCLH Committees on the Ethics of Human Research, London, UK.
Provenance and peer review Not commissioned; externally peer reviewed.