Seizure semiology and scalp EEG in MRI-negative refractory focal epilepsy

OBJECTIVEThe authors sought to determine which neurophysiological seizure-onset features seen during scalp electroencephalography (EEG) and intracerebral EEG (iEEG) monitoring are predictors of postoperative outcome in a large series of patients with drug-resistant focal epilepsy who underwent resective surgery.METHODSThe authors retrospectively analyzed the records of 75 consecutive patients with focal epilepsy, who first underwent scalp EEG and then iEEG (stereo-EEG) for presurgical assessment and who went on to undergo resective surgery between 2004 and 2015. To determine the independent prognostic factors from the neurophysiological scalp EEG and iEEG seizure-onset information, univariate and standard multivariable logistic regression analyses were used. Since scalp EEG and iEEG data were recorded at different times, the authors matched scalp seizures with intracerebral seizures for each patient using strict criteria.RESULTSA total of 3057 seizures were assessed. Forty-eight percent (36/75) of patients had a favorable outcome (Engel class I–II) after a minimum follow-up of at least 1 year. According to univariate analysis, a localized scalp EEG seizure onset (p < 0.001), a multilobar intracerebral seizure-onset zone (SOZ) (p < 0.001), and an extended SOZ (p = 0.001) were significantly associated with surgical outcome. According to multivariable analysis, the following two independent factors were found: 1) the ability of scalp EEG to localize the seizure onset was a predictor of a favorable postoperative outcome (OR 6.073, 95% CI 2.011–18.339, p = 0.001), and 2) a multilobar SOZ was a predictor of an unfavorable outcome (OR 0.076, 95% CI 0.009–0.663, p = 0.020).CONCLUSIONSThe study findings show that localization at scalp seizure onset and a multilobar SOZ were strong predictors of surgical outcome. These predictors can help to select the better candidates for resective surgery.

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Detection of epileptic activity in presumably normal EEG

Brain Communications ◽

10.1093/braincomms/fcaa104 ◽

2020 ◽

Vol 2 (2) ◽

Author(s):

Sara Baldini ◽

Francesca Pittau ◽

Gwenael Birot ◽

Vincent Rochas ◽

Miralena I Tomescu ◽

...

Keyword(s):

Focal Epilepsy ◽

Epileptic Activity ◽

Scalp Eeg ◽

Vigilance State ◽

Explained Variance ◽

Long Term Monitoring ◽

Interictal Discharges ◽

The Individual ◽

Term Monitoring

Abstract Monitoring epileptic activity in the absence of interictal discharges is a major need given the well-established lack of reliability of patients’ reports of their seizures. Up to now, there are no other tools than reviewing the seizure diary; however, seizures may not be remembered or dismissed voluntarily. In the present study, we set out to determine if EEG voltage maps of epileptogenic activity in individual patients can help to identify disease activity, even if their scalp EEG appears normal. Twenty-five patients with pharmacoresistant focal epilepsy were included. For each patient, 6 min of EEG with spikes (yes-spike) and without visually detectable epileptogenic discharges (no-spike) were selected from long-term monitoring recordings (EEG 31–37 channels). For each patient, we identified typical discharges, calculated their average and the corresponding scalp voltage map (‘spike-map’). We then fitted the spike-map for each patient on their (i) EEG epochs with visible spikes, (ii) epochs without any visible spike and (iii) EEGs of 48 controls. The global explained variance was used to estimate the presence of the spike-maps. The individual spike-map occurred more often in the spike-free EEGs of patients compared to EEGs of healthy controls (P = 0.001). Not surprisingly, this difference was higher if the EEGs contained spikes (P < 0.001). In patients, spike-maps were more frequent per second (P < 0.001) but with a shorter mean duration (P < 0.001) than in controls, for both no-spike and yes-spike EEGs. The amount of spike-maps was unrelated to clinical variables, like epilepsy severity, drug load or vigilance state. Voltage maps of spike activity are present very frequently in the scalp EEG of patients, even in presumably normal EEG. We conclude that spike-maps are a robust and potentially powerful marker to monitor subtle epileptogenic activity.

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High-frequency oscillations in scalp EEG mirror seizure frequency in pediatric focal epilepsy

Scientific Reports ◽

10.1038/s41598-019-52700-w ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 4

Author(s):

Ece Boran ◽

Johannes Sarnthein ◽

Niklaus Krayenbühl ◽

Georgia Ramantani ◽

Tommaso Fedele

Keyword(s):

Seizure Frequency ◽

Epilepsy Surgery ◽

High Frequency ◽

Focal Epilepsy ◽

Low Noise ◽

Drug Resistant ◽

Scalp Eeg ◽

High Frequency Oscillations ◽

Custom Made ◽

Active Epilepsy

Abstract High-frequency oscillations (HFO) are promising EEG biomarkers of epileptogenicity. While the evidence supporting their significance derives mainly from invasive recordings, recent studies have extended these observations to HFO recorded in the widely accessible scalp EEG. Here, we investigated whether scalp HFO in drug-resistant focal epilepsy correspond to epilepsy severity and how they are affected by surgical therapy. In eleven children with drug-resistant focal epilepsy that underwent epilepsy surgery, we prospectively recorded pre- and postsurgical scalp EEG with a custom-made low-noise amplifier (LNA). In four of these children, we also recorded intraoperative electrocorticography (ECoG). To detect clinically relevant HFO, we applied a previously validated automated detector. Scalp HFO rates showed a significant positive correlation with seizure frequency (R2 = 0.80, p < 0.001). Overall, scalp HFO rates were higher in patients with active epilepsy (19 recordings, p = 0.0066, PPV = 86%, NPV = 80%, accuracy = 84% CI [62% 94%]) and decreased following successful epilepsy surgery. The location of the highest HFO rates in scalp EEG matched the location of the highest HFO rates in ECoG. This study is the first step towards using non-invasively recorded scalp HFO to monitor disease severity in patients affected by epilepsy.

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Lateralizing and localizing value of seizure semiology: Comparison with scalp EEG, MRI and PET in patients successfully treated with resective epilepsy surgery

Seizure ◽

10.1016/j.seizure.2018.08.026 ◽

2018 ◽

Vol 61 ◽

pp. 203-208 ◽

Cited By ~ 9

Author(s):

Sherif Elwan ◽

Andreas Alexopoulos ◽

Diosely C. Silveira ◽

Prakash Kotagal

Keyword(s):

Epilepsy Surgery ◽

Seizure Semiology ◽

Scalp Eeg

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Medically resistant pediatric insular-opercular/perisylvian epilepsy. Part 2: outcome following resective surgery

Journal of Neurosurgery Pediatrics ◽

10.3171/2016.4.peds15618 ◽

2016 ◽

Vol 18 (5) ◽

pp. 523-535 ◽

Cited By ~ 25

Author(s):

Alexander G. Weil ◽

Ngoc Minh D. Le ◽

Prasanna Jayakar ◽

Trevor Resnick ◽

Ian Miller ◽

...

Keyword(s):

Parietal Lobe ◽

Functional Neuroimaging ◽

Focal Epilepsy ◽

Intractable Epilepsy ◽

Neurological Deficits ◽

Seizure Freedom ◽

Incomplete Resection ◽

Seizure Onset ◽

Scalp Eeg ◽

Initial Surgery

OBJECTIVE Seizure onset in the insular cortex as a cause of refractory epilepsy is underrepresented in the pediatric population, possibly due to difficulties localizing seizure onset in deep anatomical structures and limited surgical access to the insula, a complex anatomical structure with a rich overlying vascular network. Insular seizure semiology may mimic frontal, temporal, or parietal lobe semiology, resulting in false localization, incomplete resection, and poor outcome. METHODS The authors retrospectively reviewed the records of all pediatric patients who underwent insular cortical resections for intractable epilepsy at Miami Children's Hospital from 2009 to 2015. Presurgical evaluation included video electroencephalography monitoring and anatomical/functional neuroimaging. All patients underwent excisional procedures utilizing intraoperative electrocorticography or extraoperative subdural/depth electrode recording. RESULTS Thirteen children (age range 6 months–16 years) with intractable focal epilepsy underwent insular-opercular resection. Seven children described symptoms that were suggestive of insular seizure origin. Discharges on scalp EEG revealed wide fields. Four patients were MRI negative (i.e., there were no insular or brain abnormalities on MRI), 4 demonstrated insular signal abnormalities, and 5 had extrainsular abnormalities. Ten patients had insular involvement on PET/SPECT. All patients underwent invasive investigation with insular sampling; in 2 patients resection was based on intraoperative electrocorticography, whereas 11 underwent surgery after invasive EEG monitoring with extraoperative monitoring. Four patients required an extended insular resection after a failed initial surgery. Postoperatively, 2 patients had transient hemiplegia. No patients had new permanent neurological deficits. At the most recent follow-up (mean 43.8 months), 9 (69%) children were seizure free and 1 had greater than 90% seizure reduction. CONCLUSIONS Primary insular seizure origin should be considered in children with treatment-resistant focal seizures that are believed to arise within the perisylvian region based on semiology, widespread electrical field on scalp EEG, or insular abnormality on anatomical/functional neuroimaging. There is a reasonable chance of seizure freedom in this group of patients, and the surgical risks are low.

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Temporal Lobe Epilepsy Semiology

Epilepsy Research and Treatment ◽

10.1155/2012/751510 ◽

2012 ◽

Vol 2012 ◽

pp. 1-10 ◽

Cited By ~ 19

Author(s):

Robert D. G. Blair

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Focal Epilepsy ◽

Intractable Epilepsy ◽

Febrile Seizures ◽

Mesial Temporal Sclerosis ◽

Careful Study ◽

Seizure Onset ◽

Seizure Semiology ◽

Seizure Onset Zone

Epilepsy represents a multifaceted group of disorders divided into two broad categories, partial and generalized, based on the seizure onset zone. The identification of the neuroanatomic site of seizure onset depends on delineation of seizure semiology by a careful history together with video-EEG, and a variety of neuroimaging technologies such as MRI, fMRI, FDG-PET, MEG, or invasive intracranial EEG recording. Temporal lobe epilepsy (TLE) is the commonest form of focal epilepsy and represents almost 2/3 of cases of intractable epilepsy managed surgically. A history of febrile seizures (especially complex febrile seizures) is common in TLE and is frequently associated with mesial temporal sclerosis (the commonest form of TLE). Seizure auras occur in many TLE patients and often exhibit features that are relatively specific for TLE but few are of lateralizing value. Automatisms, however, often have lateralizing significance. Careful study of seizure semiology remains invaluable in addressing the search for the seizure onset zone.

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The utility of arterial spin labeling in the presurgical evaluation of poorly defined focal epilepsy in children

Journal of Neurosurgery Pediatrics ◽

10.3171/2020.7.peds20397 ◽

2020 ◽

pp. 1-10

Author(s):

Jack Lam ◽

Patricia Tomaszewski ◽

Guillaume Gilbert ◽

Jeremy T. Moreau ◽

Marie-Christine Guiot ◽

...

Keyword(s):

Fdg Pet ◽

Arterial Spin Labeling ◽

Focal Epilepsy ◽

Spin Labeling ◽

Seizure Outcome ◽

Z Score ◽

Presurgical Evaluation ◽

3T Mri ◽

Scalp Eeg ◽

Intracranial Recording

OBJECTIVEThe authors sought to assess the utility of arterial spin labeling (ASL) perfusion 3T-MRI for the presurgical evaluation of poorly defined focal epilepsy in pediatric patients.METHODSPseudocontinuous ASL perfusion 3T-MRI was performed in 25 consecutive children with poorly defined focal epilepsy. ASL perfusion abnormalities were detected qualitatively by visual inspection and quantitatively by calculating asymmetry index (AI) maps and significant z-score cluster maps based on successfully operated cases. ASL results were prospectively compared to scalp EEG, structural 3T-MRI, FDG-PET, ictal/interictal SPECT, magnetoencephalography (MEG), and intracranial recording results, as well as the final surgically proven epileptogenic zone (EZ) in operated patients who had at least 1 year of good (Engel class I/II) seizure outcome and positive histopathology results.RESULTSQualitative ASL perfusion abnormalities were found in 17/25 cases (68%), specifically in 17/20 MRI-positive cases (85.0%) and in none of the 5 MRI-negative cases. ASL was concordant with localizing scalp EEG findings in 66.7%, structural 3T-MRI in 90%, FDG-PET in 75%, ictal/interictal SPECT in 62.5%, and MEG in 75% of cases, and with intracranial recording results in 40% of cases. Eleven patients underwent surgery; in all 11 cases the EZ was surgically proven by positive histopathology results and the patient having at least 1 year of good seizure outcome. ASL results were concordant with this final surgically proven EZ in 10/11 cases (sensitivity 91%, specificity 50%). All 10 ASL-positive patients who underwent surgery had positive surgical pathology results and good long-term postsurgical seizure outcome at a mean follow-up of 39 months. Retrospective quantitative analysis based on significant z-score clusters found 1 true-positive result that was missed by qualitative analysis and 3 additional false-positive results (sensitivity 100%, specificity 23%).CONCLUSIONSASL supports the hypothesis regarding the EZ in poorly defined focal epilepsy cases in children. Due to its convenience and noninvasive nature, the authors recommend that ASL be added routinely to the presurgical MRI evaluation of epilepsy. Future optimized quantitative methods may improve the diagnostic yield of this technique.

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Clinical utility of distributed source modelling of interictal scalp EEG in focal epilepsy

Clinical Neurophysiology ◽

10.1016/j.clinph.2010.04.002 ◽

2010 ◽

Vol 121 (10) ◽

pp. 1726-1739 ◽

Cited By ~ 26

Author(s):

C. Plummer ◽

M. Wagner ◽

M. Fuchs ◽

S. Vogrin ◽

L. Litewka ◽

...

Keyword(s):

Clinical Utility ◽

Focal Epilepsy ◽

Distributed Source ◽

Scalp Eeg

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Publisher Correction: High-frequency oscillations in scalp EEG mirror seizure frequency in pediatric focal epilepsy

Scientific Reports ◽

10.1038/s41598-020-58621-3 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Ece Boran ◽

Johannes Sarnthein ◽

Niklaus Krayenbühl ◽

Georgia Ramantani ◽

Tommaso Fedele

Keyword(s):

Seizure Frequency ◽

High Frequency ◽

Focal Epilepsy ◽

Scalp Eeg ◽

High Frequency Oscillations

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The Impact of Lesional Factors on Seizure Outcome Following Lesionectomy as a Surgical Management of Extratemporal Epilepsy, Case Series from a Developing Country and Review of Literature.

10.21203/rs.3.rs-685046/v1 ◽

2021 ◽

Author(s):

Amr Ali Hasanain ◽

Mohamed Sawan ◽

Ahmed Mohamed Ali

Keyword(s):

Focal Epilepsy ◽

Focal Lesion ◽

Seizure Outcome ◽

Seizure Freedom ◽

Low Grade ◽

Epileptogenic Zone ◽

Seizure Semiology ◽

Radiological Data ◽

The Impact

Abstract BACKGROUNDExtratemporal lesional epilepsy can be managed with various surgical techniques such as simple lesionectomy or more extensive resections, all of which aim at targeting the epileptogenic zone which is the key for achieving a favorable outcome. This study aimed at evaluating the effectiveness of lesionectomy in the treatment of extra-temporal epilepsy associated with a lesion on radiological imaging, and to show the effect of lesional factors on seizure outcome including the anatomical location, the relation to cerebral parenchyma, the extent of surgical excision and the histopathological nature of the lesion.METHODSA prospective study on 20 patients presenting with focal epilepsy, or focal epilepsy with secondary generalized seizures with evidence of focal lesion in an extratemporal location on MRI. Lesionectomy was done and we used the Engel’s classification for seizure outcome.RESULTSLesions were mostly tumors (85 %). The frontal lobe is the most frequent locations (60 %). Low-grade glioma represented 35 % while meningioma represented 45 % of all lesions (both intra-axial and extra-axial). Four patients were lost during follow up (mean 23.31 months). For the remaining 16 patients, 13 cases were tumors (81.25%). Lesionectomy achieved seizure freedom in 68.75 %.CONCLUSIONSIn a country with limited resources, lesionectomy is a valid technique for epilepsy surgery as long as the radiological data and the seizure semiology are concordant. Total lesionectomy provides good seizure control when the clinical and radiological data are concordant with seizure semiology, in particular with tumor-related epilepsy. A study comparing postoperative seizure outcome between intra-axial and extra-axial lesions on a larger scale and with a longer follow up period is recommended.

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