Network of brain connections linked to epileptic seizures

Researchers at the University of College London (UCL) Queen Square Institute of Neurology have discovered a network of connections in the brain linked to seizures in people with epilepsy. The team believe that their findings, published in the journal Brain, will help redesign neurological operations for patients whose epilepsy can’t be controlled by medication.

There are 50 million epilepsy patients worldwide, but one in three cannot control their condition with medication. For those patients where the source of epilepsy can be pinpointed, neurosurgery can be curative. However, currently only around 30% of patients remain seizure-free in the long term in the frontal lobe.

The UCL team analysed MRI scans of 47 patients who had received surgery to their frontal lobes for epilepsy, years earlier. They found that patients had longer-term seizure freedom when nerve pathways in the brain that link the frontal lobe to deep brain structures (the thalamus and striatum, which are responsible for relaying sensory and motor signals, motor control, emotion and reward) were disconnected — with 88% of patients seizure-free after three years and 80% seizure-free at five years, compared to typical outcomes for epilepsy-treating neurosurgery (30%) in the frontal lobe. Cutting these connections did not have any negative effects on language or executive functions.

“Neurosurgery can be very effective for people with epilepsy that is not controlled with medication. However, in some patients, seizures recur years after surgery and, until now, it has not been clear why this happens,” said lead author Davide Giampiccolo.

“We now think this might be related to connections in the brain that form a network that gives rise to epileptic seizures. If this is correct, disconnecting this frontal lobe network with surgery could prevent seizures recurring years later.

“This will allow us to redesign neurosurgical operations and personalise the operations for each patient, ensuring that the right connections are cut. We hope this will lead to a great improvement in the long-term results of epilepsy surgery.”

The researchers acknowledged that all 47 patients involved in the study had epilepsy due to lesions in the frontal lobe, so epilepsy due to lesions in other brain areas may impact differently on brain reorganisation. The impact of the surgery on brain functions such as mood or emotion remains to be tested, and confirmation of the results is also needed in a larger cohort.

Image credit: iStock.com/Sewcream