Altered intrinsic brain activity associated with outcome in frontal lobe epilepsy

Xintong Wu,Hui Gao,Qiyong Gong,Qiang Yue,Dong Zhou,Weina Wang,Wenyu Liu,Nanya Hao

doi:10.1038/s41598-019-45413-7

Abstract

Frontal lobe epilepsy (FLE) is the second most common type of the focal epilepsies. Our understanding of this disease has been revolutionized over the past decade, but variable treatment outcomes persist and the underlying functional mechanisms responsible for this have yet to be deciphered. This study was designed to determine how intrinsic brain connectivity related to treatment response in patients with FLE. 50 patients with FLE and 28 healthy controls were enrolled in this study and underwent functional MRI at baseline. At the end of 12-month follow up period, all patients with FLE were classified, based on their responses to AEDs treatment, into drug-responsive and drug-refractory groups. The amplitude of low-frequency fluctuation (ALFF) was calculated amongst the three groups in order to detect regional neural function integration. The responsive group showed decreased ALFF only in the left ventromedial prefrontal cortex (vmPFC), while the refractory group showed decreased ALFF in the left vmPFC, right superior frontal gyrus (SFG), and supramarginal gyrus (SMG) relative to healthy controls. In addition, both the responsive and refractory groups showed increased ALFF in the precuneus and postcentral gyrus when compared to the healthy controls. Furthermore, the refractory group exhibited significantly decreased ALFF in the left vmPFC, right SFG and SMG, relative to the responsive group. Focal spontaneous activity, as assessed by ALFF, was associated with response to antiepileptic treatment in patients with FLE. Patients with refractory frontal lobe epilepsy exhibited decreased intrinsic brain activity. Our findings provide novel neuroimaging evidence into the mechanisms of medically-intractable FLE at the brain level.

Highlights

Affecting about 50 million people worldwide, epilepsy has in recent years been recognized as a serious public health concern[1]
We used amplitude of low-frequency fluctuations (ALFF) to examine medically-responsive and refractory patients with Frontal lobe epilepsy (FLE) to demonstrate specific alteration patterns, revealing that varying responses to antiepileptic drugs may be attributed to different patterns of intrinsic regional brain dysfunction
Previous studies have supported the finding of abnormalities in ALFF measurements of local brain activity in patients with FLE14, which are thought to potentially result from seizure-induced damage to the epileptic brain

Summary

Introduction

Affecting about 50 million people worldwide, epilepsy has in recent years been recognized as a serious public health concern[1]. The interictal discharges arising from a unilateral focus in frontal lobe are more likely to spread to both hemispheres and result in secondary bilateral synchrony[7] These phenomena implicate abnormality in multiple functional systems in FLE patients. There is considerable heterogeneity in seizure response and little data are available to identify patients with FLE who may benefit from treatment This individual variability extends to the brain networks responsible for FLE. The associations between regional activity values and epilepsy duration were examined This will further characterize brain connections in a larger sample of patients with FLE in an effort to provide deep insights into the clinical implications and resulting medical interventions utilized in FLE treatment, and may contribute to better evaluating seizure prognosis

Methods

Results

Conclusion