Interactive effects of seizure frequency and lateralization on intratemporal effective connectivity in temporal lobe epilepsy

Abstract

SummaryObjective: Patients with temporal lobe epilepsy (TLE) show brain connectivity changes in association with cognitive impairment. Seizure frequency and lateralization are 2 important clinical factors that characterize epileptic seizures. In this study, we sought to examine an interactive effect of the 2 seizure factors on intratemporal effective connectivity based on resting-state functional magnetic resonance imaging (rsfMRI) in patients with TLE. Methods: For rsfMRI data acquired from 48 TLE patients and 45 healthy controls, we applied stochastic dynamical causal modeling to infer effective connectivity between 3 medial temporal lobe (MTL) regions, including the hippocampus (Hipp), parahippocampal gyrus (PHG), and amygdala (Amyg), ipsilateral to the seizure focus. We searched for the effect of the 2 seizure factors, seizure frequency (good vs poor seizure control) and lateralization (left vs right TLE), on connection strengths and their relationship with the level of verbal memory and language impairment. Results: Impairment of verbal memory and language function was mainly affected by seizure lateralization, consistent with preferential involvement of the left MTL in verbal mnemonic processing. For the fully connected model, which was selected as the effective connectivity structure that best explained the observed rsfMRI time series, alterations in connection strengths were primarily influenced by seizure frequency; there was an increase in the strength of the Hipp to PHG connection in TLE patients with poor seizure control, whereas the strength of the Amyg to PHG connection increased in those with good seizure control. Furthermore, the association between connection strength alterations and cognitive impairment was interactively affected by both seizure frequency and lateralization. Significance: These findings suggest an interactive effect as well as an individual effect of seizure frequency and lateralization on neuroimaging features and cognitive function. This potential interaction needs to be evaluated in the consideration of multiple seizure factors. K E Y W O R D Seffective connectivity, functional MRI, language, memory, seizure frequency, seizure lateralization, temporal lobe epilepsy

Hippocampal Interictal Spikes during Sleep Impact Long‐Term Memory Consolidation

“…This result is concordant with the improvement of cognitive impairment observed after reducing seizure frequency with antiepileptic drugs . Park et al (2018) recently showed that the number of seizures and the lateralization of epilepsy were the main factors impairing verbal memory in TLE . A recent study showed that seizure control was the main factor associated with the improvement of memory and executive functioning after surgery.…”

The effect of nocturnal epileptic seizures on cognitive functions in children with idiopathic epilepsy

“…Furthermore, the cognitive consequences of NES can depend on brain maturation at NES onset [4]. However, there is an ongoing debate regarding the causal relation between NES and cognitive impairment [10].…”

“…The disturbance of executive functions in epileptic children may be caused by a number of factors, such as the underlying lesion and/or its neuro-developmental effects, interictal epileptic activity, the total drug load, drug interactions, and the lack of drive and motivation due to depression [9][10][11][12][13][14]. Recently, impaired executive functions were reported in newly diagnosed drug naïve epileptic children [15].…”

Artificial Intelligence and Computational Approaches for Epilepsy

“…The parameters of each neural mass model that determine the local regional properties can be set through the analysis of individual functional imaging data or through the clinical findings. This personalized modeling approach can be applied to specific diseases, and the developed model could reproduce the pathological characteristics of each patient, such as structural and/or functional alteration of the brain, 17 , 91 – 93 and predict the effects of various therapeutic interventions via systematic simulations in a patient-specific environment. In this section, we briefly review the personalized modeling studies toward clinical application of epilepsy.…”

“… 9 – 13 The possibility of cognitive impairment after surgery caused by the removal or severance of specific brain areas is another important issue to consider. 14 – 17 …”