Structural connections of the centromedian nucleus of thalamus and their relevance for neuromodulation in generalized drug-resistant epilepsy: insight from a tractography study

Background: Epilepsy is a widespread neurologic disorder and almost one-third of patients suffer from drug-resistant epilepsy (DRE). Neuromodulation targeting the centromediannucleus of the thalamus (CM) has been showing promising results for patients with generalized DRE who are not surgical candid...

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Main Authors: Luigi G. Remore, Ziad Rifi, Hiroki Nariai, Dawn S. Eliashiv, Aria Fallah, Benjamin D. Edmonds, Joyce H. Matsumoto, Noriko Salamon, Meskerem Tolossa, Wexin Wei, Marco Locatelli, Evangelia C. Tsolaki, Ausaf A. Bari
Format: Article
Language:English
Published: SAGE Publishing 2023-10-01
Series:Therapeutic Advances in Neurological Disorders
Online Access:https://doi.org/10.1177/17562864231202064
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author Luigi G. Remore
Ziad Rifi
Hiroki Nariai
Dawn S. Eliashiv
Aria Fallah
Benjamin D. Edmonds
Joyce H. Matsumoto
Noriko Salamon
Meskerem Tolossa
Wexin Wei
Marco Locatelli
Evangelia C. Tsolaki
Ausaf A. Bari
author_facet Luigi G. Remore
Ziad Rifi
Hiroki Nariai
Dawn S. Eliashiv
Aria Fallah
Benjamin D. Edmonds
Joyce H. Matsumoto
Noriko Salamon
Meskerem Tolossa
Wexin Wei
Marco Locatelli
Evangelia C. Tsolaki
Ausaf A. Bari
author_sort Luigi G. Remore
collection DOAJ
description Background: Epilepsy is a widespread neurologic disorder and almost one-third of patients suffer from drug-resistant epilepsy (DRE). Neuromodulation targeting the centromediannucleus of the thalamus (CM) has been showing promising results for patients with generalized DRE who are not surgical candidates. Recently, the effect of CM- deep brain stimulation (DBS) in DRE patients was investigated in the Electrical Stimulation of Thalamus for Epilepsy of Lennox–Gastaut phenotype (ESTEL) trial, a monocentric randomized-controlled study. The same authors described a ‘cold-spot’ and a ‘sweet-spot’, which are defined as the volume of stimulation in the thalamus yielding the least and the best clinical response, respectively. However, it remains unclear which structural connections may contribute to the anti-seizure effect of the stimulation. Objective: We investigated the differences in structural connectivity among CM, the sweet-spot and the cold-spot. Furthermore, we tried to validate our results in a cohort of DRE patients who underwent CM-DBS or CM-RNS (responsive neurostimulation). We hypothesized that the sweet-spot would share similar structural connectivity with responder patients. Methods: By using the software FMRIB Software Library (FSL), probabilistic tractography was performed on 100 subjects from the Human Connectome Project to calculate the probability of connectivity of the whole CM, the sweet-spot and the cold-spot to 45 cortical and subcortical areas. Results among the three seeds were compared with multivariate analysis of variance (MANOVA). Similarly, the structural connectivity of volumes of tissue activated (VTAs) from eight DRE patients was investigated. Patients were divided into responders and non-responders based on the degree of reduction in seizure frequency, and the mean probabilities of connectivity were similarly compared between the two groups. Results: The sweet-spot demonstrated a significantly higher probability of connectivity ( p  < 0.001) with the precentral gyrus, superior frontal gyrus, and the cerebellum than the whole CM and the cold-spot. Responder patients displayed a higher probability of connectivity with both ipsilateral ( p  = 0.011) and contralateral cerebellum ( p  = 0.04) than the non-responders. Conclusion: Cerebellar connections seem to contribute to the beneficial effects of CM-neuromodulation in patients with drug-resistant generalized epilepsy.
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spelling doaj.art-5023ca5bb9534aecba77e29cd7380de82023-10-10T13:33:27ZengSAGE PublishingTherapeutic Advances in Neurological Disorders1756-28642023-10-011610.1177/17562864231202064Structural connections of the centromedian nucleus of thalamus and their relevance for neuromodulation in generalized drug-resistant epilepsy: insight from a tractography studyLuigi G. RemoreZiad RifiHiroki NariaiDawn S. EliashivAria FallahBenjamin D. EdmondsJoyce H. MatsumotoNoriko SalamonMeskerem TolossaWexin WeiMarco LocatelliEvangelia C. TsolakiAusaf A. BariBackground: Epilepsy is a widespread neurologic disorder and almost one-third of patients suffer from drug-resistant epilepsy (DRE). Neuromodulation targeting the centromediannucleus of the thalamus (CM) has been showing promising results for patients with generalized DRE who are not surgical candidates. Recently, the effect of CM- deep brain stimulation (DBS) in DRE patients was investigated in the Electrical Stimulation of Thalamus for Epilepsy of Lennox–Gastaut phenotype (ESTEL) trial, a monocentric randomized-controlled study. The same authors described a ‘cold-spot’ and a ‘sweet-spot’, which are defined as the volume of stimulation in the thalamus yielding the least and the best clinical response, respectively. However, it remains unclear which structural connections may contribute to the anti-seizure effect of the stimulation. Objective: We investigated the differences in structural connectivity among CM, the sweet-spot and the cold-spot. Furthermore, we tried to validate our results in a cohort of DRE patients who underwent CM-DBS or CM-RNS (responsive neurostimulation). We hypothesized that the sweet-spot would share similar structural connectivity with responder patients. Methods: By using the software FMRIB Software Library (FSL), probabilistic tractography was performed on 100 subjects from the Human Connectome Project to calculate the probability of connectivity of the whole CM, the sweet-spot and the cold-spot to 45 cortical and subcortical areas. Results among the three seeds were compared with multivariate analysis of variance (MANOVA). Similarly, the structural connectivity of volumes of tissue activated (VTAs) from eight DRE patients was investigated. Patients were divided into responders and non-responders based on the degree of reduction in seizure frequency, and the mean probabilities of connectivity were similarly compared between the two groups. Results: The sweet-spot demonstrated a significantly higher probability of connectivity ( p  < 0.001) with the precentral gyrus, superior frontal gyrus, and the cerebellum than the whole CM and the cold-spot. Responder patients displayed a higher probability of connectivity with both ipsilateral ( p  = 0.011) and contralateral cerebellum ( p  = 0.04) than the non-responders. Conclusion: Cerebellar connections seem to contribute to the beneficial effects of CM-neuromodulation in patients with drug-resistant generalized epilepsy.https://doi.org/10.1177/17562864231202064
spellingShingle Luigi G. Remore
Ziad Rifi
Hiroki Nariai
Dawn S. Eliashiv
Aria Fallah
Benjamin D. Edmonds
Joyce H. Matsumoto
Noriko Salamon
Meskerem Tolossa
Wexin Wei
Marco Locatelli
Evangelia C. Tsolaki
Ausaf A. Bari
Structural connections of the centromedian nucleus of thalamus and their relevance for neuromodulation in generalized drug-resistant epilepsy: insight from a tractography study
Therapeutic Advances in Neurological Disorders
title Structural connections of the centromedian nucleus of thalamus and their relevance for neuromodulation in generalized drug-resistant epilepsy: insight from a tractography study
title_full Structural connections of the centromedian nucleus of thalamus and their relevance for neuromodulation in generalized drug-resistant epilepsy: insight from a tractography study
title_fullStr Structural connections of the centromedian nucleus of thalamus and their relevance for neuromodulation in generalized drug-resistant epilepsy: insight from a tractography study
title_full_unstemmed Structural connections of the centromedian nucleus of thalamus and their relevance for neuromodulation in generalized drug-resistant epilepsy: insight from a tractography study
title_short Structural connections of the centromedian nucleus of thalamus and their relevance for neuromodulation in generalized drug-resistant epilepsy: insight from a tractography study
title_sort structural connections of the centromedian nucleus of thalamus and their relevance for neuromodulation in generalized drug resistant epilepsy insight from a tractography study
url https://doi.org/10.1177/17562864231202064
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