Detrended fluctuation analysis in the presurgical evaluation of parietal lobe epilepsy patients

Sami Auno,Leena Lauronen,Juha Wilenius,Maria Peltola,Sampsa Vanhatalo,J Matias Palva

doi:10.1016/j.clinph.2021.03.041

Abstract

ObjectiveTo examine the usability of long-range temporal correlations (LRTCs) in non-invasive localization of the epileptogenic zone (EZ) in refractory parietal lobe epilepsy (RPLE) patients. MethodsWe analyzed 10 RPLE patients who had presurgical MEG and underwent epilepsy surgery. We quantified LRTCs with detrended fluctuation analysis (DFA) at four frequency bands for 200 cortical regions estimated using individual source models. We correlated individually the DFA maps to the distance from the resection area and from cortical locations of interictal epileptiform discharges (IEDs). Additionally, three clinical experts inspected the DFA maps to visually assess the most likely EZ locations. ResultsThe DFA maps correlated with the distance to resection area in patients with type II focal cortical dysplasia (FCD) (p<0.05), but not in other etiologies. Similarly, the DFA maps correlated with the IED locations only in the FCD II patients. Visual analysis of the DFA maps showed high interobserver agreement and accuracy in FCD patients in assigning the affected hemisphere and lobe. ConclusionsAberrant LRTCs correlate with the resection areas and IED locations. SignificanceThis methodological pilot study demonstrates the feasibility of approximating cortical LRTCs from MEG that may aid in the EZ localization and provide new non-invasive insight into the presurgical evaluation of epilepsy.

Highlights

More than 30% of all patients with epilepsy continue to have seizures despite medication (Del Felice et al, 2010)
The cornerstones of presurgical evaluation are seizure semiology, magnetic resonance imaging (MRI), positron emission tomography (PET), and scalp electroencephalography (EEG) that may be complemented with magnetoencephalography (MEG)
Akin to the clinical visual assessment of any processed neuroimaging data, we sought out to first determine whether a visual assessment of the detrended fluctuation analysis (DFA) maps could provide a reliable prediction of the epileptogenic zone (EZ)

Summary

Introduction

More than 30% of all patients with epilepsy continue to have seizures despite medication (Del Felice et al, 2010). Epilepsy surgery offers an important treatment option for these patients ⇑ Corresponding author at: BABA Center (www.babacenter.fi), Department of Clinical Neurophysiology, University of Helsinki, PO Box 280, 00029 HUS, Helsinki, Finland. The success of surgery is heavily dependent on the accuracy of presurgical localization of the epileptogenic zone (EZ). The cornerstones of presurgical evaluation are seizure semiology, magnetic resonance imaging (MRI), positron emission tomography (PET), and scalp electroencephalography (EEG) that may be complemented with magnetoencephalography (MEG).

Methods

Results

Conclusion