Abnormal brain areas common to the focal epilepsies: Multivariate pattern analysis of fMRI.

Brain Connect. 2015 Nov 5;

Authors: Pedersen M, Curwood EK, Vaughan DN, Omidvarnia AH, Jackson G

Abstract
Individuals with focal epilepsy have heterogeneous sites of seizure origin. However, there may be brain regions that are common to most cases of intractable focal epilepsy. In this study we aim to identify these using multivariate analysis of task-free functional MRI. Fourteen subjects with extratemporal focal epilepsy and fourteen healthy controls were included in the study. Task-free functional MRI data was used to calculate voxel-wise regional connectivity with Regional Homogeneity (ReHo) and weighted Degree Centrality (DCw), in addition to regional activity using fraction of Amplitude of Low Frequency Fluctuations (fALFF). Multivariate pattern analysis was applied to each of these metrics to discriminate brain areas that differed between focal epilepsy subjects and healthy controls. ReHo and DCw classified focal epilepsy subjects from healthy controls with high accuracy (89.3 % and 75 % respectively). However, fALFF did not significantly classify patients from controls. Increased regional network activity in epilepsy subjects was seen in ipsilateral piriform cortex, insula and thalamus, in addition to dorsal anterior cingulate cortex and lateral frontal cortices. Decreased regional connectivity was observed in ventromedial prefrontal cortex, as well as lateral temporal cortices. Patients with extratemporal focal epilepsy have common areas of abnormality (ReHo and DCw measures) including the ipsilateral piriform cortex, temporal neocortex and ventromedial prefrontal cortex. ReHo shows additional increase in the 'salience network' that includes anterior insula and anterior cingulate cortex. DCw showed additional effects in the ipsilateral thalamus and striatum. These brain areas may represent key regional network properties underlying focal epilepsy.

PMID: 26537783 [PubMed - as supplied by publisher]