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An EEG-fMRI Study on the Termination of Generalized Spike-And-Wave Discharges in Absence Epilepsy.

Benuzzi F, Ballotta D, Mirandola L, Ruggieri A, Vaudano AE, Zucchelli M, Ferrari E, Nichelli PF, Meletti S - PLoS ONE (2015)

Bottom Line: At GSWD termination we observed a decrease in BOLD signal over the bilateral dorsolateral frontal cortex respect to the baseline (and respect to GSWD onset).Parametric correlations between electro-clinical variables and BOLD signal at GSWD offset did not reveal significant effects.The role of the decreased neural activity of lateral prefrontal cortex at GSWD termination deserve future investigations to ascertain if it has a role in promoting the discharge offset, as well as in the determination of the cognitive deficits often present in patients with AS.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy.

ABSTRACT

Introduction: Different studies have investigated by means of EEG-fMRI coregistration the brain networks related to generalized spike-and-wave discharges (GSWD) in patients with idiopathic generalized epilepsy (IGE). These studies revealed a widespread GSWD-related neural network that involves the thalamus and regions of the default mode network. In this study we investigated which brain regions are critically involved in the termination of absence seizures (AS) in a group of IGE patients.

Methods: Eighteen patients (6 male; mean age 25 years) with AS were included in the EEG-fMRI study. Functional data were acquired at 3T with continuous simultaneous video-EEG recording. Event-related analysis was performed with SPM8 software, using the following regressors: (1) GSWD onset and duration; (2) GSWD offset. Data were analyzed at single-subject and at group level with a second level random effect analysis.

Results: A mean of 17 events for patient was recorded (mean duration of 4.2 sec). Group-level analysis related to GSWD onset respect to rest confirmed previous findings revealing thalamic activation and a precuneus/posterior cingulate deactivation. At GSWD termination we observed a decrease in BOLD signal over the bilateral dorsolateral frontal cortex respect to the baseline (and respect to GSWD onset). The contrast GSWD offset versus onset showed a BOLD signal increase over the precuneus-posterior cingulate region bilaterally. Parametric correlations between electro-clinical variables and BOLD signal at GSWD offset did not reveal significant effects.

Conclusion: The role of the decreased neural activity of lateral prefrontal cortex at GSWD termination deserve future investigations to ascertain if it has a role in promoting the discharge offset, as well as in the determination of the cognitive deficits often present in patients with AS. The increased BOLD signal at precuneal/posterior cingulate cortex might reflect the recovery of neural activity in regions that are "suspended" during spike and waves activity, as previously hypothesized.

No MeSH data available.


Related in: MedlinePlus

Brain regions showing BOLD signal changes at absence seizures termination.A. Areas of increased signal for the condition GSWD offset versus GSWD onset. B. Areas of decreased signal for the condition GSWD offset versus rest. Maps are superimposed on the template image MRICro (http://www.mccauslandcenter.sc.edu/mricro/index.html) and are thresholded at p ≤ 0.001 uncorrected for multiple comparisons, with a cluster extent threshold (k) of 10 voxels (p ≤ 0.05). Color bar represents T-values.
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pone.0130943.g001: Brain regions showing BOLD signal changes at absence seizures termination.A. Areas of increased signal for the condition GSWD offset versus GSWD onset. B. Areas of decreased signal for the condition GSWD offset versus rest. Maps are superimposed on the template image MRICro (http://www.mccauslandcenter.sc.edu/mricro/index.html) and are thresholded at p ≤ 0.001 uncorrected for multiple comparisons, with a cluster extent threshold (k) of 10 voxels (p ≤ 0.05). Color bar represents T-values.

Mentions: No significant BOLD increase was observed at spike-and-waves termination compared with the resting normal EEG background (GSWD offset versus rest). BOLD signal increases at spike-and-waves termination were found in the precuneus/posterior cingulate region comparing GSWD offset with respect to GSWD onset (Table 2; Fig 1A). On the contrary, frontal regions showed a decrease in BOLD signal either comparing GSWD offset with respect to the resting baseline, as well as with respect to the GSWD onset: clusters of decreased signal occurred in the dorso-lateral frontal cortex of both hemisphere and particularly in the left precentral, middle and inferior frontal gyrus (BA 4, 9) and in the right middle and inferior frontal gyrus (BA 9, 44, 8; Table 3; Fig 1B). A decrease of BOLD signal at GSWD offset involving the frontal cortex was consistently observed also at single-subject level. Indeed 12 out of 18 patients showed a deactivation of the dorsolateral prefrontal cortex at discharge offset at a threshold of p < 0.001 uncorrected (Fig 2).


An EEG-fMRI Study on the Termination of Generalized Spike-And-Wave Discharges in Absence Epilepsy.

Benuzzi F, Ballotta D, Mirandola L, Ruggieri A, Vaudano AE, Zucchelli M, Ferrari E, Nichelli PF, Meletti S - PLoS ONE (2015)

Brain regions showing BOLD signal changes at absence seizures termination.A. Areas of increased signal for the condition GSWD offset versus GSWD onset. B. Areas of decreased signal for the condition GSWD offset versus rest. Maps are superimposed on the template image MRICro (http://www.mccauslandcenter.sc.edu/mricro/index.html) and are thresholded at p ≤ 0.001 uncorrected for multiple comparisons, with a cluster extent threshold (k) of 10 voxels (p ≤ 0.05). Color bar represents T-values.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4496065&req=5

pone.0130943.g001: Brain regions showing BOLD signal changes at absence seizures termination.A. Areas of increased signal for the condition GSWD offset versus GSWD onset. B. Areas of decreased signal for the condition GSWD offset versus rest. Maps are superimposed on the template image MRICro (http://www.mccauslandcenter.sc.edu/mricro/index.html) and are thresholded at p ≤ 0.001 uncorrected for multiple comparisons, with a cluster extent threshold (k) of 10 voxels (p ≤ 0.05). Color bar represents T-values.
Mentions: No significant BOLD increase was observed at spike-and-waves termination compared with the resting normal EEG background (GSWD offset versus rest). BOLD signal increases at spike-and-waves termination were found in the precuneus/posterior cingulate region comparing GSWD offset with respect to GSWD onset (Table 2; Fig 1A). On the contrary, frontal regions showed a decrease in BOLD signal either comparing GSWD offset with respect to the resting baseline, as well as with respect to the GSWD onset: clusters of decreased signal occurred in the dorso-lateral frontal cortex of both hemisphere and particularly in the left precentral, middle and inferior frontal gyrus (BA 4, 9) and in the right middle and inferior frontal gyrus (BA 9, 44, 8; Table 3; Fig 1B). A decrease of BOLD signal at GSWD offset involving the frontal cortex was consistently observed also at single-subject level. Indeed 12 out of 18 patients showed a deactivation of the dorsolateral prefrontal cortex at discharge offset at a threshold of p < 0.001 uncorrected (Fig 2).

Bottom Line: At GSWD termination we observed a decrease in BOLD signal over the bilateral dorsolateral frontal cortex respect to the baseline (and respect to GSWD onset).Parametric correlations between electro-clinical variables and BOLD signal at GSWD offset did not reveal significant effects.The role of the decreased neural activity of lateral prefrontal cortex at GSWD termination deserve future investigations to ascertain if it has a role in promoting the discharge offset, as well as in the determination of the cognitive deficits often present in patients with AS.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy.

ABSTRACT

Introduction: Different studies have investigated by means of EEG-fMRI coregistration the brain networks related to generalized spike-and-wave discharges (GSWD) in patients with idiopathic generalized epilepsy (IGE). These studies revealed a widespread GSWD-related neural network that involves the thalamus and regions of the default mode network. In this study we investigated which brain regions are critically involved in the termination of absence seizures (AS) in a group of IGE patients.

Methods: Eighteen patients (6 male; mean age 25 years) with AS were included in the EEG-fMRI study. Functional data were acquired at 3T with continuous simultaneous video-EEG recording. Event-related analysis was performed with SPM8 software, using the following regressors: (1) GSWD onset and duration; (2) GSWD offset. Data were analyzed at single-subject and at group level with a second level random effect analysis.

Results: A mean of 17 events for patient was recorded (mean duration of 4.2 sec). Group-level analysis related to GSWD onset respect to rest confirmed previous findings revealing thalamic activation and a precuneus/posterior cingulate deactivation. At GSWD termination we observed a decrease in BOLD signal over the bilateral dorsolateral frontal cortex respect to the baseline (and respect to GSWD onset). The contrast GSWD offset versus onset showed a BOLD signal increase over the precuneus-posterior cingulate region bilaterally. Parametric correlations between electro-clinical variables and BOLD signal at GSWD offset did not reveal significant effects.

Conclusion: The role of the decreased neural activity of lateral prefrontal cortex at GSWD termination deserve future investigations to ascertain if it has a role in promoting the discharge offset, as well as in the determination of the cognitive deficits often present in patients with AS. The increased BOLD signal at precuneal/posterior cingulate cortex might reflect the recovery of neural activity in regions that are "suspended" during spike and waves activity, as previously hypothesized.

No MeSH data available.


Related in: MedlinePlus