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Does the Thalamo-Cortical Synchrony Play a Role in Seizure Termination?

Evangelista E, Bénar C, Bonini F, Carron R, Colombet B, Régis J, Bartolomei F - Front Neurol (2015)

Bottom Line: We performed a measure of SEEG signal interdependencies (non-linear correlation), to estimate the functional connectivity between thalamus and cortical regions.Thalamus was consistently involved in the last phase of all analyzed seizures and thalamic synchronization index was significantly more elevated at the end of seizure than at the onset.We suggest that thalamo-cortical oscillations might contribute to seizure termination via modulation of cortical synchronization.

View Article: PubMed Central - PubMed

Affiliation: Service de Neurophysiologie Clinique, CHU Timone, Assistance Publique des Hôpitaux de Marseille , Marseille , France.

ABSTRACT
The mechanisms underlying seizure termination are still unclear despite their therapeutic importance. We studied thalamo-cortical connectivity and synchrony in human mesial temporal lobe seizures in order to analyze their role in seizure termination. Twenty-two seizures from 10 patients with drug-resistant mesial temporal lobe epilepsy undergoing pre-surgical evaluation were analyzed using intracerebral recordings [stereoelectroencephalography (SEEG)]. We performed a measure of SEEG signal interdependencies (non-linear correlation), to estimate the functional connectivity between thalamus and cortical regions. Then, we derived synchronization indices, namely global, thalamic, mesio-temporal, and thalamo-mesio temporal index at the onset and the end of seizures. In addition, an estimation of thalamic "outputs and inputs" connectivity was proposed. Thalamus was consistently involved in the last phase of all analyzed seizures and thalamic synchronization index was significantly more elevated at the end of seizure than at the onset. The global synchronization index at the end of seizure negatively correlated with seizure duration (p = 0.045) and in the same way the thalamic synchronization index showed an inverse tendency with seizure duration. Six seizures out of twenty-two displayed a particular thalamo-cortical spike-and-wave pattern at the end. They were associated to higher values of all synchronization indices and outputs from thalamus (p = 0.0079). SWP seizures displayed a higher and sustained increase of cortical and thalamo-cortical synchronization with a stronger participation of thalamic outputs. We suggest that thalamo-cortical oscillations might contribute to seizure termination via modulation of cortical synchronization. In the subgroup of SWP seizures, thalamus may exert a control on temporal lobe structures by inducing a stable hypersynchronization that ultimately leads to seizure termination.

No MeSH data available.


Related in: MedlinePlus

Comparison between group A and B. (A) Mean and standard deviation of synchronization indices derived from ES period for the two groups; all synchronization indices were significantly higher in pattern A than pattern B seizures (Mann–Whitney test, global index p = 0.0004, Th index p = 0.0004, Th-MT index p = 0.0063, and MT index p = 0.0015). (B) Mean and standard deviation of thalamic output graph measures (Th OUT) in group A and B (p = 0.0079). (C) Pattern A seizures showed higher thalamic synchronization indices (Th index) and thalamic output measures (Th OUT) than pattern B seizures in the ES period. (D) Mean of seizure duration in group A and group B. No statistical difference between seizure A and seizure B duration, but pattern A group had only short seizures, while pattern B included a wide range of seizure duration.
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Figure 4: Comparison between group A and B. (A) Mean and standard deviation of synchronization indices derived from ES period for the two groups; all synchronization indices were significantly higher in pattern A than pattern B seizures (Mann–Whitney test, global index p = 0.0004, Th index p = 0.0004, Th-MT index p = 0.0063, and MT index p = 0.0015). (B) Mean and standard deviation of thalamic output graph measures (Th OUT) in group A and B (p = 0.0079). (C) Pattern A seizures showed higher thalamic synchronization indices (Th index) and thalamic output measures (Th OUT) than pattern B seizures in the ES period. (D) Mean of seizure duration in group A and group B. No statistical difference between seizure A and seizure B duration, but pattern A group had only short seizures, while pattern B included a wide range of seizure duration.

Mentions: We compared the synchronization indices and the direction indices derived from ES period between pattern A and pattern B seizures. All synchronization indices were significantly higher in pattern A than pattern B group (global index p = 0.0004, Th index p = 0.0004, Th-MT index p = 0.0063, and MT index p = 0.0015) (Figure 4A).


Does the Thalamo-Cortical Synchrony Play a Role in Seizure Termination?

Evangelista E, Bénar C, Bonini F, Carron R, Colombet B, Régis J, Bartolomei F - Front Neurol (2015)

Comparison between group A and B. (A) Mean and standard deviation of synchronization indices derived from ES period for the two groups; all synchronization indices were significantly higher in pattern A than pattern B seizures (Mann–Whitney test, global index p = 0.0004, Th index p = 0.0004, Th-MT index p = 0.0063, and MT index p = 0.0015). (B) Mean and standard deviation of thalamic output graph measures (Th OUT) in group A and B (p = 0.0079). (C) Pattern A seizures showed higher thalamic synchronization indices (Th index) and thalamic output measures (Th OUT) than pattern B seizures in the ES period. (D) Mean of seizure duration in group A and group B. No statistical difference between seizure A and seizure B duration, but pattern A group had only short seizures, while pattern B included a wide range of seizure duration.
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Related In: Results  -  Collection

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Figure 4: Comparison between group A and B. (A) Mean and standard deviation of synchronization indices derived from ES period for the two groups; all synchronization indices were significantly higher in pattern A than pattern B seizures (Mann–Whitney test, global index p = 0.0004, Th index p = 0.0004, Th-MT index p = 0.0063, and MT index p = 0.0015). (B) Mean and standard deviation of thalamic output graph measures (Th OUT) in group A and B (p = 0.0079). (C) Pattern A seizures showed higher thalamic synchronization indices (Th index) and thalamic output measures (Th OUT) than pattern B seizures in the ES period. (D) Mean of seizure duration in group A and group B. No statistical difference between seizure A and seizure B duration, but pattern A group had only short seizures, while pattern B included a wide range of seizure duration.
Mentions: We compared the synchronization indices and the direction indices derived from ES period between pattern A and pattern B seizures. All synchronization indices were significantly higher in pattern A than pattern B group (global index p = 0.0004, Th index p = 0.0004, Th-MT index p = 0.0063, and MT index p = 0.0015) (Figure 4A).

Bottom Line: We performed a measure of SEEG signal interdependencies (non-linear correlation), to estimate the functional connectivity between thalamus and cortical regions.Thalamus was consistently involved in the last phase of all analyzed seizures and thalamic synchronization index was significantly more elevated at the end of seizure than at the onset.We suggest that thalamo-cortical oscillations might contribute to seizure termination via modulation of cortical synchronization.

View Article: PubMed Central - PubMed

Affiliation: Service de Neurophysiologie Clinique, CHU Timone, Assistance Publique des Hôpitaux de Marseille , Marseille , France.

ABSTRACT
The mechanisms underlying seizure termination are still unclear despite their therapeutic importance. We studied thalamo-cortical connectivity and synchrony in human mesial temporal lobe seizures in order to analyze their role in seizure termination. Twenty-two seizures from 10 patients with drug-resistant mesial temporal lobe epilepsy undergoing pre-surgical evaluation were analyzed using intracerebral recordings [stereoelectroencephalography (SEEG)]. We performed a measure of SEEG signal interdependencies (non-linear correlation), to estimate the functional connectivity between thalamus and cortical regions. Then, we derived synchronization indices, namely global, thalamic, mesio-temporal, and thalamo-mesio temporal index at the onset and the end of seizures. In addition, an estimation of thalamic "outputs and inputs" connectivity was proposed. Thalamus was consistently involved in the last phase of all analyzed seizures and thalamic synchronization index was significantly more elevated at the end of seizure than at the onset. The global synchronization index at the end of seizure negatively correlated with seizure duration (p = 0.045) and in the same way the thalamic synchronization index showed an inverse tendency with seizure duration. Six seizures out of twenty-two displayed a particular thalamo-cortical spike-and-wave pattern at the end. They were associated to higher values of all synchronization indices and outputs from thalamus (p = 0.0079). SWP seizures displayed a higher and sustained increase of cortical and thalamo-cortical synchronization with a stronger participation of thalamic outputs. We suggest that thalamo-cortical oscillations might contribute to seizure termination via modulation of cortical synchronization. In the subgroup of SWP seizures, thalamus may exert a control on temporal lobe structures by inducing a stable hypersynchronization that ultimately leads to seizure termination.

No MeSH data available.


Related in: MedlinePlus