Seizure Frequency Can Alter Brain Connectivity: Evidence from Resting-State fMRI

Editor’s Choice

Editor’s Comments

Resting-state fMRI data from 36 patients with hot-water epilepsy (18 with infrequent seizures) and 18 healthy age- and sex-matched controls were analyzed for seed-to-voxel connectivity. Patients in the frequent-seizure group had increased connectivity within the medial temporal structures and widespread areas of poor connectivity, including the default mode network. Seizure frequency can alter functional brain connectivity, which can be visualized by resting-state fMRI.

Abstract

Whole-brain cluster-correlation maps of seed-to-voxel–based resting-state functional connectivity for the PCC seed region (FDR-corrected P < .001). Shown is DMN connectivity using PCC seed at 3 different axial levels: at the level of ventricles in the top row, midbrain in the middle row, and the cerebellum in the bottom row for healthy controls (A), the infrequent-seizure group (B), the frequent-seizure group (C), the infrequent-seizure group versus healthy controls (D), the frequent-seizure group versus healthy controls (E), and the infrequent-seizure group versus the frequent-seizure group (F). The colors represent the significance of connectivity; red indicates an increase in connectivity, and blue indicates a decrease in connectivity.
Whole-brain cluster-correlation maps of seed-to-voxel–based resting-state functional connectivity for the PCC seed region (FDR-corrected P < .001). Shown is DMN connectivity using PCC seed at 3 different axial levels: at the level of ventricles in the top row, midbrain in the middle row, and the cerebellum in the bottom row for healthy controls (A), the infrequent-seizure group (B), the frequent-seizure group (C), the infrequent-seizure group versus healthy controls (D), the frequent-seizure group versus healthy controls (E), and the infrequent-seizure group versus the frequent-seizure group (F). The colors represent the significance of connectivity; red indicates an increase in connectivity, and blue indicates a decrease in connectivity.

BACKGROUND AND PURPOSE

The frequency of seizures is an important factor that can alter functional brain connectivity. Analysis of this factor in patients with epilepsy is complex because of disease- and medication-induced confounders. Because patients with hot-water epilepsy generally are not on long-term drug therapy, we used seed-based connectivity analysis in these patients to assess connectivity changes associated with seizure frequency without confounding from antiepileptic drugs.

MATERIALS AND METHODS

Resting-state fMRI data from 36 patients with hot-water epilepsy (18 with frequent seizures [>2 per month] and 18 with infrequent seizures [≤2 per month]) and 18 healthy age- and sex-matched controls were analyzed for seed-to-voxel connectivity by using 106 seeds. Voxel wise paired t-test analysis (P < .005, corrected for false-discovery rate) was used to identify significant intergroup differences between these groups.

RESULTS

Connectivity analysis revealed significant differences between the 2 groups (P < .001). Patients in the frequent-seizure group had increased connectivity within the medial temporal structures and widespread areas of poor connectivity, even involving the default mode network, in comparison with those in the infrequent-seizure group. Patients in the infrequent-seizure group had focal abnormalities with increased default mode network connectivity and decreased left entorhinal cortex connectivity.

CONCLUSIONS

The results of this study suggest that seizure frequency can alter functional brain connectivity, which can be visualized by using resting-state fMRI. Imaging features such as diffuse network abnormalities, involvement of the default mode network, and recruitment of medial temporal lobe structures were seen only in patients with frequent seizures. Future studies in more common epilepsy groups, however, will be required to further establish this finding.

Read this article: http://bit.ly/BrainConnectivity

Seizure Frequency Can Alter Brain Connectivity: Evidence from Resting-State fMRI
jross
Jeffrey Ross • Mayo Clinic, Phoenix

Dr. Jeffrey S. Ross is a Professor of Radiology at the Mayo Clinic College of Medicine, and practices neuroradiology at the Mayo Clinic in Phoenix, Arizona. His publications include over 100 peer-reviewed articles, nearly 60 non-refereed articles, 33 book chapters, and 10 books. He was an AJNR Senior Editor from 2006-2015, is a member of the editorial board for 3 other journals, and a manuscript reviewer for 10 journals. He became Editor-in-Chief of the AJNR in July 2015. He received the Gold Medal Award from the ASSR in 2013.