Patients with frontal lobe epilepsy may have effective compensatory mechanism to maintain memory function


A small study led by Matthias Koepp, UCL Institute of Neurology, London, UK, publishing ahead of print in Epilepsia, stated that, memory impairment in frontal lobe epilepsy remained unclear. Therefore, the authors aimed to find the underlying mechanism and remote effects of frontal lobe epilepsy on the temporal lobe regions. 

In order to assess this Keopp et al used a functional magnetic resonance imaging (fMRI) memory encoded paradigm to investigate in patients with frontal lobe epilepsy; memory encoding and recognition performance; characterisation of the brain regions involved in memory; the effect on frontotemporal brain networks and the remote effect on the medial temporal lobe; the effect of seizure focus lateralisation and how the functional brain correlates memory impairment.

In the study, 32 patients with drug-resistant frontal lobe epilepsy were diagnosed using prolonged video electroencephalography (EEG) monitoring, seizure semiology and fMRI memory encoding paradigm. The fMRI contained different types of visual stimuli in which the subjects were to actively memorise and underwent a recognition test 60 minutes post-scanning.

The results showed that, during encoding of stimuli, patients with frontal lobe epilepsy recruited more widely than the controls, which is suggestive that normal memory function which is recruited from frontal areas, that in patients with frontal lobe epilepsy there is an effective compensatory mechanism to maintain memory function.

“Our fMRI data provide provides evidence for the involvement of both the frontal and the medial temporal lobe areas,” Koepp et al said. “However our analysis did not reveal common areas of decreased activation within the front lobes across the whole frontal lobe epilepsy group for the sub-group of patients with memory impairment.”

“Studying memory in patients affected by epilepsy provides us with a window to the brain: it shows rich and complex connections between various brain regions and ability of the brain to compensate (or not) for disturbing interference from epilepsy.” added Koepp.