Overview
Surgery is an important option for children with epilepsy that doesn’t respond to drug treatments. But, unfortunately, brain operations can damage the nerve cells and pathways involved in vision.
Studies in adults have shown that advanced magnetic resonance imaging (MRI) can be used to map the visual brain, but there haven’t been any studies in children yet. This is important because adult brains are different to children’s, including differences in the nature of epilepsy and visual problems after surgery.
The researchers have three aims in this study. 1) To find out whether they can use brain imaging to map the visual pathway in children. This needs both to be accurate and repeatable. 2) To see if they can use the imaging data to measure an important distance between a key part of the visual pathway and a part of the brain often removed during epilepsy surgery. This information will be given to the surgeon to help guide the operation. 3) To compare imaging data from before and after surgery. This will mean they can show how removing brain tissue affects the child’s vision.
This is the first study of its kind in children. At the end of the project the team should have enough evidence to pave the way for a clinical trial showing that this type of assessment can improve visual outcomes for children having this surgery.
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Scientific summary
Investigation of optic radiation mapping using MRI for surgical planning of children with epilepsy and avoidance of post-surgical visual field defect
The overall aim of the proposed research programme is to investigate mapping the optic radiations using an MRI technique called tractography for the purposes of planning surgery of the temporal/parietal/occipital lobes in children with intractable epilepsy in order to avoid post-surgical visual dysfunction. This investigation will evaluate a preventative measure that could help avoid or reduce damage to children’s vision as a result of an essential surgical procedure performed to reduce or eliminate harmful on-going epileptic seizures.
The team is testing the following hypotheses (i) that the optic radiations can be robustly and reproducibly mapped in children undergoing pre-surgical MRI scans prior to surgery; (ii) the distance between Meyer’s loop and the temporal pole can be measured and provided to the surgeon in all cases and the reconstructed optic radiation displayed in a neuro-navigation system; (iii) that the extent of optic-radiation involvement determined by comparison of the pre and post-surgical MRI data correlates with severity of visual dysfunction in children undergoing surgery.
This study is paving the way for a future clinical trial to show that imaging visual pathways before surgery can reduce problems with visual function following surgery.