For medication-resistant epileptics, surgery is often the only way to stop seizures. However, for those with frontal lobe epilepsy, sometimes surgery doesn’t ensure the seizures stop. A new study has uncovered connections in the brain that go some way to explaining why some frontal lobe surgeries are more successful in stopping seizures long term.
As one of the most common neurological diseases, epilepsy affects around 50 million people worldwide. Frontal lobe epilepsy is a common form of epilepsy characterized by brief seizures that usually occur during sleep.
Medication- or drug-resistant epilepsy – also known as uncontrolled, intractable, or refractory epilepsy – is commonly treated surgically, where the portion of the brain generating the seizures is removed. The surgery is most effective when seizure activity is localized to a single location. But, for epileptics who undergo resection of the frontal lobe for seizures originating there, less than 30% remain seizure-free in the long term.
Researchers at University College London sought answers to this issue by delving into the frontal lobes of patients who’d undergone previous frontal lobe resection.
After analyzing the MRI scans of 47 patients who’d had frontal lobe surgery between 2007 and 2021, the researchers found that being free of seizures in the long term was associated with disconnection of the nerve pathways that link the frontal lobe to the thalamus and striatum of the brain.
The thalamus is an egg-shaped structure in the middle of the brain, a relay station for all incoming motor and sensory information. It’s also responsible for keeping you awake and is connected to the brain’s limbic system, which processes and regulates emotions, forms and stores memories, and is involved in learning. The striatum is a collection of structures – the caudate, putamen, and nucleus accumbens – best known for facilitating voluntary movement but also plays a role in the brain’s reward system.
The researchers found that, in patients where this particular nerve pathway had been severed, 88% were seizure-free after three years and 80% at five years, compared to typical outcomes for frontal lobe resection. Importantly, the surgery had not negatively affected the patients’ language or executive functioning – a set of mental skills that include working memory, flexible thinking, and self-control.
These findings go a long way to explaining why resection works for some and not for others, say the researchers.
“Neurosurgery can be very effective for people with epilepsy that is not controlled with medication,” said Davide Giampiccolo, lead author of the study. “However, in some patients, seizures recur years after surgery and, until now, it has not been clear why this happens. We now think this might be related to connections in the brain that form a network that gives rise to epileptic seizures.”
Identifying and then ‘disconnecting’ the problematic parts of the frontal lobe network could not only prevent epileptic seizures, the researchers say, but lead to more effective – and individualized – neurosurgical treatment.
“This will allow us to redesign neurosurgical operations and personalize the operations for each patient, ensuring that the right connections are cut,” Giampiccolo said. “We hope this will lead to a great improvement in the long-term results of epilepsy surgery.”
The researchers intend to confirm their findings using a larger cohort of patients.
The study was published in the journal Brain.
Source: University College London
