Dynamic gray matter and intrinsic activity changes after epilepsy surgery

Abstract

Objectives To explore the dynamic changes of gray matter volume and intrinsic brain activity following anterior temporal lobectomy (ATL) in patients with unilateral mesial temporal lobe epilepsy (mTLE) who achieved seizure‐free for 2 years. Materials and Methods High‐resolution T1‐weighted MRI and resting‐state functional MRI data were obtained in ten mTLE patients at five serial timepoints: before surgery, 3, 6, 12, and 24 months after surgery. The gray matter volume (GMV) and amplitude of low‐frequency fluctuations (ALFF) were compared among the five scans to depict the dynamic changes after ATL. Results After successful ATL, GMV decreased in several ipsilateral brain regions: ipsilateral insula, thalamus, and putamen showed gradual gray matter atrophy from 3 to 24 months, while ipsilateral superior temporal gyrus, middle temporal gyrus, inferior temporal gyrus, middle occipital gyrus, inferior occipital gyrus, caudate nucleus, lingual gyrus, and fusiform gyrus showed significant GMV decrease at 3 months follow‐up, without further changes. Ipsilateral insula showed gradual ALFF decrease from 3 to 24 months after surgery. Ipsilateral superior temporal gyrus showed ALFF decrease at 3 months follow‐up, without further changes. Ipsilateral thalamus and cerebellar vermis showed obvious ALFF increase after surgery. Conclusions Surgical resection may lead to a short‐term reduction of gray matter volume and intrinsic brain activity in neighboring regions, while the progressive gray matter atrophy may be due to possible intrinsic mechanism of mTLE. Dynamic ALFF changes provide evidence that disrupted focal spontaneous activities were reorganized after successful surgery.

Structural and functional reorganization of contralateral hippocampus after temporal lobe epilepsy surgery

“…We previously explored the longitudinal diffusion and amplitude of low-frequency fluctuations (ALFF) alterations in mTLE patients and revealed postsurgical structural and functional reorganizations from the whole brain level ( Li et al, 2019 , Li et al, 2021 ). In this study, we focused on the key structure of mTLE and assessed the longitudinal GMV and FC changes of contralateral hippocampus in mTLE patients who achieved seizure-freedom after ATL for at least two years.…”

Relation of Brain Perfusion Patterns to Sudden Unexpected Death Risk Stratification: A Study in Drug Resistant Focal Epilepsy

“…Furthermore, no differences in the number and PI of the hyperperfused and hypoperfused subcortical and cortical structures between the evaluated epilepsy types were found. As can be seen in Table 2, there was a tendency towards a greater number of the hypoperfused subcortical structures (8)(9)(10)(11)(12) and hyperperfused cortical structures (10)(11)(12)(13).…”

“…Numerous advances in structural and functional neuroimaging and computational neuroscience suggest that neural dysfunction in focal epilepsy is not restricted to the epileptogenic zone (EZ) but can affect widespread networks throughout the brain. These findings may lead to improved strategies for outcome prediction in epilepsy and EZ localization [ 7 , 8 , 9 , 10 ].…”

Cortical remodeling before and after successful temporal lobe epilepsy surgery

“…16 Previously, we also found progressive gray matter atrophy in ipsilateral insula in patients achieved seizure freedom after surgery. 15 The possible reason of progressive cortical thinning may be the underlying pathologic mechanism of mTLE, similarly to the progression of gray matter atrophy in seizure-free TLE patients. 14 Another possibility may be the effects of ASMs since ASMs were thought to be associated with reduced cortical thickness and brain volume.…”

“…Structural MRI have revealed extensive gray matter atrophy 6–9 and cortical thinning 10–12 in mTLE. Longitudinal study demonstrated that mTLE may lead to progressive gray matter atrophy with the course of epilepsy, 13 even in patients who achieved seizure freedom for at least 2 years through antiseizure medications (ASMs) therapy 14 or epilepsy surgery, 15 suggesting a probable underlying pathological mechanism other than ongoing seizures. In addition, it was reported that progressive cortical thinning advanced in focal epilepsy patients at a rate more than twice that of normal aging, especially in the first five years after epilepsy onset 16 …”