Cortical Thickness Changes as a Potential Biomarker for Epilepsy in People with First-Time Unprovoked Seizure
Abstract
Accurate epilepsy diagnosis after a First-Time Unprovoked Seizure (FTUS) remains challenging as the epileptogenic abnormalities and epileptiform EEG abnormalities used for such diagnoses infrequently occur and are often missed or misinterpreted. Expanding the scope of diagnostic abnormalities to include cortical thickness changes could enhance diagnostic efficacy. This is because cortical thickness changes are a significantly prevalent pathophysiological change that occurs in cases of epilepsy progressively, independent of seizure frequency, drug load and age. These changes are theorised to be a product of epileptogenesis, the process in which brain networks undergo disruptions becoming epileptic. This study aims to investigate whether these changes can be used for epilepsy diagnosis by determining if epileptogenic brain network changes and cortical thickness changes are present as early as the FTUS of epilepsy. In this study, 16 healthy controls and 16 FTUS patients were recruited and underwent 7T structural Magnetic Resonance Imaging (MRI) scans; of the 16 FTUS patients, six were confirmed to be epileptic (CE). The participants' MRI scans were parcellated using the 17-network Schaefer 200 and 100 parcellation maps. Within these maps, the average cortical thicknesses per region were measured for each participant group and used for between-group comparisons. These comparisons contrasted the cortical thicknesses of the FTUS patients with their age- and sex-matched healthy controls (HC) and the cortical thicknesses of solely the CE patients with their age- and sex-matched HC. Each between-group comparison included both mixed-sex and sex-based comparisons. The cortical thickness measures were used for structural covariance analysis, with the calculated nodal and global measures undergoing the same set of between-group comparisons conducted for the cortical thickness measures. No statistically significant differences in cortical thickness were observed in any of the comparisons. At both parcellation levels, the CE patients displayed sex-dependent statistically significant differences in their structural covariance nodal measures. These differences indicate that brain network changes are present as early as the FTUS and support the theory that the cortical thickness changes observed in people with epilepsy are a byproduct of the network disruptions observed in epilepsy. Indicating that cortical thickness changes are not an ideal diagnostic symptom for epilepsy.