Intracranial EEG analysis in tumor-related epilepsy: Evidence of distant epileptic abnormalities

Mittal, Sandeep; Barkmeier, Daniel; Hua, Jing; Pai, Darshan; Fuerst, Darren R.; Basha, Maysaa; Loeb, Jeffrey A.; Shah, Aashit

doi:10.1016/j.clinph.2015.06.028

Cited by 77 publications

(55 citation statements)

References 38 publications

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“…Patients with a tumor close to eloquent cortex have a diminished chance of seizure freedom a priori, because complete resection might be impossible. Studies that used staged surgery guided by invasive EEG, like the study of Mittal et al (2015), have found irritative cortex in situ after lesionectomy, and obtained good seizure outcome with additional resection of the irritative area (Rassi-Neto et al, 1999;Mikuni et al, 2006). These results are in line with the hypothesis that not the lesion per se, but the surrounding tissue could be epileptogenic (Rosenow and Luders, 2001).…”

supporting

confidence: 64%

“…They compared these patients with 14 patients with non-lesional refractory epilepsy, and found the seizure onset zone located in multiple lobes in both groups. Mittal et al (2015) conclude that the seizure onset zone in tumor related epilepsy is often distant from the tumor border and that lesionectomy alone is not enough if you aim for seizure freedom. They suggest that exploration of the epileptogenic area would be useful in all patients with tumor related refractory epilepsy.…”

mentioning

confidence: 94%

“…In this issue of Clinical Neurophysiology, Mittal et al (2015) describe long-term depth EEG findings in 11 patients with low grade primary brain tumors and refractory epilepsy. They looked at the seizure onset and early seizure spread zone, and interical epileptiform discharges, and compared these at different distances from the tumor border.…”

mentioning

confidence: 99%

“…We do this by studying the evidence from literature including the study by Mittal et al (2015), from our own database, and a common expert opinion in our center.…”

mentioning

confidence: 99%

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Brain surgery in tumor related epilepsy

Klink

Zijlmans

2016

Clinical Neurophysiology

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supporting

confidence: 64%

mentioning

confidence: 94%

mentioning

confidence: 99%

“…We do this by studying the evidence from literature including the study by Mittal et al (2015), from our own database, and a common expert opinion in our center.…”

mentioning

confidence: 99%

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Brain surgery in tumor related epilepsy

Klink

Zijlmans

2016

Clinical Neurophysiology

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“…However, at that time, study was descriptive and the lack of computer does not allow mapping or connectivity measures. Recent EcoG works focused on tumour related epilepsia (Tran et al 1997;Mittal et al 2015). Imaging tumours by intraoperative electrophysiology may allow better identification of the tumour from the eloquent healthy adjacent areas to improve the quality of surgical resection.…”

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confidence: 99%

In Vivo Tumour Mapping Using Electrocorticography Alterations During Awake Brain Surgery: A Pilot Study

et al. 2016

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During awake brain surgery for tumour resection, in situ EEG recording (ECoG) is used to identify eloquent areas surrounding the tumour. We used the ECoG setup to record the electrical activity of cortical and subcortical tumours and then performed frequency and connectivity analyses in order to identify ECoG impairments and map tumours. We selected 16 patients with cortical (8) and subcortical (8) tumours undergoing awake brain surgery. For each patient, we computed the spectral content of tumoural and healthy areas in each frequency band. We computed connectivity of each electrode using connectivity markers (linear and non-linear correlations, phase-locking and coherence). We performed comparisons between healthy and tumour electrodes. The ECoG alterations were used to implement automated classification of the electrodes using clustering or neural network algorithms. ECoG alterations were used to image cortical tumours.Cortical tumours were found to profoundly alter all frequency contents (normalized and absolute power), with an increase in the δ activity and a decreases for the other bands (P < 0.05). Cortical tumour electrodes showed high level of connectivity compared to surrounding electrodes (all markers, P < 0.05). For subcortical tumours, a relative decrease in the γ1 band and in the alpha band in absolute amplitude (P < 0.05) were the only abnormalities. The neural network algorithm classification had a good performance: 93.6 % of the electrodes were classified adequately on a test subject. We found significant spectral and connectivity ECoG changes for cortical tumours, which allowed tumour recognition. Artificial neural algorithm pattern recognition seems promising for electrode classification in awake tumour surgery.

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Objective 3D surface evaluation of intracranial electrophysiologic correlates of cerebral glucose metabolic abnormalities in children with focal epilepsy

Jeong

Asano

Pilli

et al. 2017

Human Brain Mapping

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To determine the spatial relationship between 2-deoxy-2[18F]fluoro-D-glucose (FDG) metabolic and intracranial electrophysiological abnormalities in children undergoing two-stage epilepsy surgery, we used statistical parametric mapping (SPM) to correlate hypo- and hypermetabolic cortical regions with ictal and interictal electrocorticography (ECoG) changes mapped onto the brain surface. Preoperative FDG-PET scans of 37 children with intractable epilepsy (31 with non-localizing MRI) were compared to age-matched pseudo-normal pediatric control PET data. Hypo-/hypermetabolic maps were transformed to 3D-MRI brain surface to compare the locations of metabolic changes with electrode coordinates of the ECoG-defined seizure onset zone (SOZ) and interictal spiking. While hypometabolic clusters showed a good agreement with the SOZ on the lobar level (sensitivity/specificity=0.74/0.64), detailed surface-distance analysis demonstrated that large portions of ECoG-defined SOZ and interictal spiking area were located at least 3cm beyond hypometabolic regions with the same statistical threshold (sensitivity/specificity=0.18–0.25/0.94–0.90 for overlap-3cm distance); for a lower threshold, sensitivity for SOZ at 3cm increased to 0.39 with a modest compromise of specificity. Performance of FDG-PET SPM was slightly better in children with smaller as compared to widespread SOZ. The results demonstrate that SPM utilizing age-matched pseudocontrols can reliably detect the lobe of seizure onset. However, the spatial mismatch between metabolic and EEG epileptiform abnormalities indicates that a more complete SOZ detection could be achieved by extending intracranial electrode coverage at least 3cm beyond the metabolic abnormality. Considering that the extent of feasible electrode coverage is limited, localization information from other modalities is particularly important to optimize grid coverage in cases of large hypometabolic cortex.

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Intracranial EEG analysis in tumor-related epilepsy: Evidence of distant epileptic abnormalities

Cited by 77 publications

References 38 publications

Brain surgery in tumor related epilepsy

Brain surgery in tumor related epilepsy

In Vivo Tumour Mapping Using Electrocorticography Alterations During Awake Brain Surgery: A Pilot Study

Objective 3D surface evaluation of intracranial electrophysiologic correlates of cerebral glucose metabolic abnormalities in children with focal epilepsy

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