Most children with epilepsy can control their seizures using anti-seizure drugs. However, about 30% will continue to have seizures despite taking medication, a condition known as drug-resistant epilepsy. Previous research has suggested that ongoing seizures may affect the structure of the brain, particularly in a region known as the hippocampus. The hippocampus is a structure deep within the brain that is important for memory function. Specifically, the hippocampus helps us to form new memories. Some studies have shown a reduction in the size of the hippocampus in children with epilepsy. This suggests that ongoing seizures may lead to structural changes, but it’s unclear if these changes are stable or if they progress over time.
EpLink researcher Dr. Elysa Widjaja and her colleagues at SickKids hospital scanned 37 children with drug-resistant epilepsy using magnetic resonance imaging, or MRI. They took high-resolution images of the children’s brains at two timepoints. The first scan served as a baseline, and the follow-up scan, which was on average 2.5 years later, was used to observe any changes in the size of the hippocampus.
The researchers analyzed these changes in two ways: first, they looked at the average change across the whole group of children, and then they looked at each child individually. When taken as a group, the researchers found the size of the hippocampus did not change over time. However, when looking at children individually, the researchers found that 25 of 37 had a 10% or more reduction in hippocampal size at the follow-up scan. This suggests that some children may be more likely to have a reduction in the size of the hippocampus due to seizures. However, the researchers found no links between changes in the size of the hippocampus and seizure frequency, type of seizures, duration of epilepsy, or use of anti-seizure drugs.
In conclusion, this study found no change in the size of the hippocampus over time in a group of children with drug-resistant epilepsy. However, changes may occur in individual children. Further studies are needed to better understand the impact of seizures on hippocampal size, and how these changes may influence memory function.