Minimally resective epilepsy surgery in MRI‐negative children

Aim. Performing epilepsy surgery on children with non‐lesional brain MRI often results in large lobar or multilobar resections. The aim of this study was to determine if smaller resections result in a comparable rate of seizure freedom. Methods. We reviewed 25 children who had undergone focal corticectomies restricted to one aspect of a single lobe or the insula at our institution within a 5.5‐year period. Data collected in the comprehensive non‐invasive pre‐surgical evaluation (including scalp video‐EEG, volumetric MRI, functional MRI, EEG source localization, and SPECT and PET), as well as from invasive recordings performed in each patient, was reviewed. Data from each functional modality was identified as convergent or divergent with the epileptogenic zone using image coregistration. Specific biomarkers (from extra‐operative and invasive testing) previously indicated to be indicative of focal epileptogenicity were used to further tailor each resection to an epileptogenic epicentre. Tissue pathology and postoperative outcomes were obtained from all 25 patients. Results. Two years postoperatively, 15/25 (60%) children were seizure‐free, three (12%) experienced >90% reduction in seizure frequency, two (8%) had a 50–90% reduction in seizure frequency, and the remaining five (20%) had no change in seizure burden. There was no significant difference in outcome based on numerous pre‐ and postoperative factors including location of resection, the number of preoperative functional tests providing convergent data, and tissue pathology. Conclusion. In MRI‐negative children with focal epilepsy, an epileptogenic epicentre within a larger epileptogenic zone can be identified when specific biomarkers are recognized on non‐invasive and invasive testing. When such children undergo resection of a small, well‐defined epileptogenic epicentre, favourable outcomes can be achieved.     

Epileptic networks in focal cortical dysplasia revealed using electroencephalography-functional magnetic resonance imaging

Objective:

Surgical treatment of focal epilepsy in patients with focal cortical dysplasia (FCD) is most successful if all epileptogenic tissue is resected. This may not be evident on structural magnetic resonance imaging (MRI), so intracranial electroencephalography (icEEG) is needed to delineate the seizure onset zone (SOZ). EEG‐functional MRI (fMRI) can reveal interictal discharge (IED)‐related hemodynamic changes in the irritative zone (IZ). We assessed the value of EEG‐fMRI in patients with FCD‐associated focal epilepsy by examining the relationship between IED‐related hemodynamic changes, icEEG findings, and postoperative outcome.

Methods:

Twenty‐three patients with FCD‐associated focal epilepsy undergoing presurgical evaluation including icEEG underwent simultaneous EEG‐fMRI at 3T. IED‐related hemodynamic changes were modeled, and results were overlaid on coregistered T1‐weighted MRI scans fused with computed tomography scans showing the intracranial electrodes. IED‐related hemodynamic changes were compared with the SOZ on icEEG and postoperative outcome at 1 year.

Results:

Twelve of 23 patients had IEDs during recording, and 11 of 12 had significant IED‐related hemodynamic changes. The fMRI results were concordant with the SOZ in 5 of 11 patients, all of whom had a solitary SOZ on icEEG. Four of 5 had >50% reduction in seizure frequency following resective surgery. The remaining 6 of 11 patients had widespread or discordant regions of IED‐related fMRI signal change. Five of 6 had either a poor surgical outcome (<50% reduction in seizure frequency) or widespread SOZ precluding surgery.

Interpretation:

Comparison of EEG‐fMRI with icEEG suggests that EEG‐fMRI may provide useful additional information about the SOZ in FCD. Widely distributed discordant regions of IED‐related hemodynamic change appear to be associated with a widespread SOZ and poor postsurgical outcome. ANN NEUROL 2011     

Ictal SPECT in Nonlesional Extratemporal Epilepsy

Summary:  Purpose: Ictal single-photon emission computed tomography (SPECT) may be a reliable indicator of the ictal onset zone in patients with intractable partial epilepsy who are being considered for epilepsy surgery. The rationale for the illustrated case report is to evaluate the use of an innovation in SPECT imaging in a patient with nonlesional extratemporal epilepsy.
Methods: We investigated the presurgical evaluation and operative outcome in a patient with intractable partial epilepsy. The ictal semiology indicated a "hypermotor" seizure with bipedal automatism. The electroclinical correlation and magnetic resonance imaging (MRI) did not suggest the appropriate localization of the epileptogenic zone. A subtraction periictal SPECT coregistered to MRI (SISCOM) was peformed.
Results: SISCOM revealed a region of localized hyperperfusion in the right supplementary sensorimotor area. Chronic intracranial EEG monitoring confirmed the relationship between the localized SISCOM alteration and the ictal onset zone. The patient was rendered seizure free after surgical treatment.
Conclusions: SISCOM may be used to identify potential candidates for surgical treatment of nonlesional extratemporal epilepsy. Periictal imaging may also alter the strategy for intracranial EEG recordings and focal cortical resection.     

Drug‐resistant parietal lobe epilepsy: clinical manifestations and surgery outcome

Aim. We reviewed a large surgical cohort to investigate the clinical manifestations, EEG and neuroimaging findings, and postoperative seizure outcome in patients with drug‐resistant parietal lobe epilepsy (PLE). Methods. All drug‐resistant PLE patients, who were investigated for epilepsy surgery at Jefferson Comprehensive Epilepsy Center between 1986 and 2015, were identified. Demographic data, seizure data, EEG recordings, brain MRI, pathological findings, and postsurgical seizure outcome were reviewed. Results. In total, 18 patients (11 males and seven females) were identified. Sixteen patients (88%) had tonic‐clonic seizures, 12 (66%) had focal seizures with impaired awareness, and 13 (72%) described auras. Among 15 patients who had brain MRI, 14 patients (93%) had parietal lobe lesions. Only three of 15 patients (20%) who had interictal scalp EEG recordings showed parietal interictal spikes. Of 12 patients with available ictal surface EEG recordings, only three patients (25%) had parietal ictal EEG onset. After a mean follow‐up duration of 8.6 years, 14 patients (77.7%) showed a favourable postoperative seizure outcome. Conclusion. In patients with PLE, semiology and EEG may be misleading and brain MRI is the most valuable tool to localize the epileptogenic zone. Postsurgical seizure outcome was favourable in our patients with drug‐resistant parietal lobe epilepsy.     

Resection of Frontal Encephalomalacias for Intractable Epilepsy: Outcome and Prognostic Factors

Summary: Purpose: Because focal encephalomalacia is an important cause of medically intractable partial epilepsy and few studies have evaluated the efficacy and the safety of resecting focal encephalomalacias to improve seizure control, we studied a cohort of 17 consecutive patients who underwent resection of encephalomalacias in the frontal lobes as a treatment of their intractable epilepsy. Methods: We evaluated several factors for their value in predicting postsurgical seizure control. Pre- and postsurgical magnetic resonance imaging (MRI) scans were reviewed independently by 2 blinded investigators. Results: At a median of 3 years of follow-up (range 0.6–7.5 years), 12 patients (70%) were seizure-free or had only rare seizures. The presence of a focal fast frequency discharge (focal ictal β pattern) at the beginning of seizures on scalp EEG was predictive of seizure-free outcome (p = 0.017), even among patients who had complete resection of their encephalomalacias (p = 0.016). There was no significant differences in outcome with regard to age at the time of the injury that caused encephalomalacia, interval between injury and onset of seizures, duration of presurgical seizure history, presurgical seizure frequency, age at surgery, or the completeness of encephalomalacia resection. The analysis regarding completeness of encephalomalacia resection almost reached significance, suggesting that it may also be an important predictive factor (p = 0.051). Conclusions: We conclude that surgery is a very effective treatment for intractable frontal lobe epilepsy (FLE) secondary to encephalomalacias. Patients are more likely to become seizure-free if they have a focal ictal β discharge on their scalp EEG. Complete resection of the encephalomalacia should be attempted, since our results suggest that this may be a favorable predictive factor. Moreover, the operative strategy for our patients entailed, whenever possible, complete resection of the encephalomalacias and of the adjacent electrophysiologically abnormal tissues.     

Ictal SPECT is useful in localizing the epileptogenic zone in infants with cortical dysplasia

Aims. To assess the localizing value of ictal SPECT in very young epilepsy surgery candidates when cerebral haemodynamic responses are known to be immature. Methods. We retrospectively studied 13 infants with intractable focal epilepsy caused by focal cortical dysplasia (FCD). Completeness of resection of the (1) ictal SPECT hyperperfusion zone and (2) cerebral cortex with prominent ictal and interictal abnormalities on intracranial EEG (ECoG or long‐term invasive monitoring) and the MRI lesion, when present, were correlated with postoperative seizure outcome. Results. All five patients with complete resection of the ictal SPECT hyperperfusion zone were seizure‐free compared to only one of eight patients with incomplete or no excision of hyperperfusion zones (p=0.00843). Similar results were noted for the MRI/iEEG‐defined epileptogenic region; five of six patients with complete removal were seizure‐free, whereas only one of seven incompletely resected patients was seizure‐free (p=0.02914). All four patients who underwent complete resection of both regions were seizure‐free compared to none of the six with incomplete resection (p=0.01179). Conclusion. Despite age‐related differences in cerebral perfusion, ictal SPECT provides useful localization data in infants with FCD. Complete resection of the hyperperfused regions is a strong predictor of favourable outcome. The added information may alleviate the need for invasive EEG evaluations in some patients.     

Magnetic source imaging and ictal SPECT in MRI‐negative neocortical epilepsies: Additional value and comparison with intracranial EEG

Purpose: To investigate the utility of magnetic source imaging (MSI) and ictal single photon emission computed tomography (SPECT), each compared with intracranial electroencephalography (EEG) (ICEEG), to localize the epileptogenic zone (EZ) and predict epilepsy surgery outcome in patients with nonlesional neocortical focal epilepsy. Methods: Studied were 14 consecutive patients with nonlesional neocortical epilepsy who underwent presurgical evaluation including ICEEG, positive MSI, and localizing subtraction Ictal SPECT coregistered to MRI (SISCOM) analysis. Follow‐up after epilepsy surgery was ≥24 months. ICEEG, MSI, and SPECT results were classified using a sublobar classification. Key Findings: Of 14 patients, 6 (42.9%) became seizure‐free after surgery. Sublobar ICEEG focus was completely resected in 11 patients; 5 (45.5%) of them became seizure‐ free. Concordance of ICEEG and MSI and complete focus resection was found in 5 (35.7%) patients; 80% of them became seizure‐free. Sublobar ICEEG‐MSI concordance and complete focus resection significantly increased the chance of seizure freedom after epilepsy surgery (p = 0.038). In contrast, of the 6 patients (42.9%) with concordant ICEEG and SISCOM and complete focus resection, only 66.7% became seizure‐free (p = 0.138). Assuming concordant results, the additive value to ICEEG alone for localizing the EZ is higher with ICEEG‐MSI (odds ratio 14) compared to ICEEG‐SISCOM (odds ratio 6). Significance: This study shows that combination of MSI and/or SISCOM with ICEEG is useful in the presurgical evaluation of patients with nonlesional neocortical epilepsy. Concordant test results of either MSI or SISCOM with ICEEG provide useful additive information for that provided by ICEEG alone to localize the EZ in this most challenging group of patients. When sublobar concordance with ICEEG is observed, MSI is more advantageous compared to SISCOM in predicting seizure‐free epilepsy surgery outcome.     

Prospective use of subtraction ictal SPECT coregistered to MRI (SISCOM) in presurgical evaluation of epilepsy

Purpose: In patients with drug‐refractory focal epilepsy, nonlesional magnetic resonance imaging (MRI) or discordant data of presurgical standard investigations leads to failure generating a sufficient hypothesis for electrode implantation or epilepsy surgery. The seizure‐onset zone can be further investigated by subtraction ictal single‐photon emission computed tomography (SPECT) coregistered to MRI (SISCOM). This is an observational study of a large consecutive cohort of patients undergoing prospective SISCOM to generate hypothesis for electrode implantation or site of epilepsy surgery. Methods: One hundred seventy‐five consecutive patients undergoing presurgical evaluation with either nonlesional MRI or discordant data of standard investigations preventing the generation of hypothesis for seizure onset were evaluated with SISCOM. Results were compared to gold standard for seizure onset detection, either electrocorticography (ECoG) and/or postoperative outcome. Key Findings: One hundred thirty patients had successful SPECT injection. Hypothesis for electrode implantation/site of surgery was generated in 74 patients. Forty patients had gold standard comparison. Twenty‐eight patients underwent resective surgery. SISCOM was concordant to site of surgery in 82%. An additional 12 patients underwent invasive EEG monitoring but were not suitable for surgery. SISCOM was concordant multifocal in 75%. Two years postsurgical follow‐up of 26 patients showed favorable outcome in 22 (Engel class I and class II). Significance: SISCOM is a highly valuable diagnostic tool to localize the seizure‐onset zone in nonlesional and extratemporal epilepsies. Outcome in this patient group was unexpectedly good, even in patients with nonlesional MRI. The high correlation with ECoG and site of successful surgery is a strong indicator that outcome prediction in this patient group should be adapted accordingly, which may encourage more patients to undergo electrode implantation and subsequent successful surgery. Statistical analysis showed that SISCOM with shorter duration of seizures, focal seizures, and lesional MRI was more likely to generate implantation hypothesis.     

Additional clinical value of voxel‐based morphometric MRI post‐processing for MRI‐negative epilepsies: a prospective study

Aims: Magnetic resonance imaging is of paramount importance in the presurgical evaluation of drug resistant epilepsy. Detection of a potentially epileptogenic lesion significantly improves seizure outcome after surgery. To optimize the detection of subtle lesions, MRI post‐processing techniques may be of essential help. Methods: In this study, we aimed to evaluate the detection rate of the voxel‐based morphometric analysis program (MAP) in a prospective trial. We aimed to study the MAP+ findings in terms of their clinical value in the decision‐making process of the presurgical evaluation. Results: We included, prospectively, 21 patients who had negative MRI by visual analysis. In a first step, results of the conventional non‐invasive presurgical evaluation were discussed, blinded to the MAP results, in multidisciplinary patient management conferences to determine the possible seizure onset zone and to set surgical or invasive evaluation plans. Thereafter, MAP results were presented, and the change of initial clinical plan was recorded. All MAP detections were reaffirmed by a neuroradiologist with epilepsy expertise. For the 21 patients included, mean age at the time of patient management conference was 26 years (SD 15 +/‐ years, range: 5–54 years). In total, 4/21 had temporal lobe epilepsy and 17/21 had extra‐temporal lobe epilepsy. MAP was positive in 10/21 (47%) patients and in 6/10 (60%) a diagnosis of focal cortical dysplasia was confirmed after neuroradiologist review, corresponding to a 28% detection rate. MAP+ findings had a clear impact on the initial management in 7/10 patients (7/21, 33% of all patients), which included an adaptation of the intracranial EEG plan (6/7 patients), or the decision to proceed directly to surgery (1/7 patients). Conclusion: MRI post‐processing using the MAP method yielded an increased detection rate of 28% for subtle dysplastic lesions in a prospective cohort of MRI‐negative patients, indicating its potential value in epilepsy presurgical evaluation.     

A population-based study of long-term outcomes of cryptogenic focal epilepsy in childhood: cryptogenic epilepsy is probably not symptomatic epilepsy

Purpose: To compare long‐term outcome in a population‐based group of children with cryptogenic versus symptomatic focal epilepsy diagnosed from 1980 to 2004 and to define the course of epilepsy in the cryptogenic group. Methods: We identified all children residing in Olmsted County, MN, 1 month through 17 years, with newly diagnosed, nonidiopathic focal epilepsy from 1980 to 2004. Children with idiopathic partial epilepsy syndromes were excluded. Medical records were reviewed to determine etiology, results of imaging and EEG studies, treatments used, and long‐term outcome. Children were defined as having symptomatic epilepsy if they had a known genetic or structural/metabolic etiology, and as cryptogenic if they did not. Key Findings: Of 359 children with newly diagnosed epilepsy, 215 (60%) had nonidiopathic focal epilepsy. Of these, 206 (96%) were followed for >12 months. Ninety‐five children (46%) were classified as symptomatic. Median follow‐up from diagnosis was similar in both groups, being 157 months (25%, 75%: 89, 233) in the cryptogenic group versus 134 months (25%, 75%: 78, 220) in the symptomatic group (p = 0.26). Of 111 cryptogenic cases, 66% had normal cognition. Long‐term outcome was significantly better in those with cryptogenic versus symptomatic etiology (intractable epilepsy at last follow‐up, 7% vs. 40%, p < 0.001; seizure freedom at last follow‐up, 81% vs. 55%, p < 0.001). Of those who achieved seizure freedom at final follow‐up, 68% of the cryptogenic group versus only 46% of the symptomatic group were off antiepileptic medications (p = 0.01). One‐third of the cryptogenic group had a remarkably benign disorder, with no seizures seen after initiation of medication, or in those who were untreated, after the second afebrile seizure. A further 5% had seizures within the first year but remained seizure‐free thereafter. With the exception of perinatal complications, which predicted against seizure remission, no other factors were found to significantly predict outcome in the cryptogenic group. Significance: More than half of childhood nonidiopathic localization‐related epilepsy is cryptogenic. This group has a significantly better long‐term outcome than those with a symptomatic etiology, and should be distinguished from it.     

Electrical source imaging for presurgical focus localization in epilepsy patients with normal MRI

Purpose: Patients with magnetic resonance (MR)–negative focal epilepsy (MRN‐E) have less favorable surgical outcomes (between 40% and 70%) compared to those in whom an MRI lesion guides the site of surgical intervention (60–90%). Patients with extratemporal MRN‐E have the worst outcome (around 50% chance of seizure freedom). We studied whether electroencephalography (EEG) source imaging (ESI) of interictal epileptic activity can contribute to the identification of the epileptic focus in patients with normal MRI. Methods: We carried out ESI in 10 operated patients with nonlesional MRI and a postsurgical follow‐up of at least 1 year. Five of the 10 patients had extratemporal lobe epilepsy. Evaluation comprised surface and intracranial EEG monitoring of ictal and interictal events, structural MRI, [¹⁸F]fluorodeoxyglucose positron emission tomography (FDG‐PET), ictal and interictal perfusion single photon emission computed tomography (SPECT) scans. Eight of the 10 patients also underwent intracranial monitoring. Results: ESI correctly localized the epileptic focus within the resection margins in 8 of 10 patients, 9 of whom experienced favorable postsurgical outcomes. Discussion: The results highlight the diagnostic value of ESI and encourage broadening its application to patients with MRN‐E. If the surface EEG contains fairly localized spikes, ESI contributes to the presurgical decision process.     

Surgery for drug‐resistant tuberous sclerosis complex‐associated epilepsy: who,when, and what

Objective: Tuberous sclerosis complex (TSC) is a multisystem genetic disorder associated with refractory early‐onset epilepsy. Current evidence supports surgery as the intervention most likely to achieve long‐term seizure freedom, but no specific guidelines are available on TSC pre‐surgical workup. This critical review assesses which TSC patients are suitable for surgical treatment, when pre‐surgical evaluation should start, and what degree of surgical resection is optimal for postsurgical outcome. Methods: We searched for publications from 2000 to 2020 in Pubmed and Embase using the terms “tuberous sclerosis,” “epilepsy,” and “epilepsy surgery”. To evaluate postsurgical seizure outcome, we selected only studies with at least one year of follow‐up. Results: Overall, we collected data on 1,026 patients from 34 studies. Age at surgery ranged from one month to 54 years. Mean age at surgery was 8.41 years. Of the diagnostic non‐invasive pre‐surgical tools, MRI and video‐EEG were considered most appropriate. Promising data for epileptogenic tuber detection is provided from invasive SEEG studies. Data on surgery and related outcome were available for 769 patients. Seizure freedom was seen in 64.4% of patients who underwent tuberectomy, 68.9% treated with lobectomy and 65.1% with multilobar resection. The most effective surgical approach was lobectomy, even though more recently tuberectomy associated with the resection of the perituberal area seems to be the best approach to reach seizure freedom. Published postsurgical seizure freedom rates in patients with TSC were between 65% and 75%, but reduced to 48%‐57% over longer follow‐up periods. Early surgery might positively affect neurodevelopmental trajectory in some patients, even though data on cognitive outcome are still to be confirmed with longitudinal studies. Significance: Considering the strong correlation between epilepsy duration and neurocognitive outcome, all patients with TSC ought to be referred early to a dedicated epilepsy centre for individually tailored pre‐surgical evaluation by a multi‐disciplinary epilepsy surgery team.     

Epilepsy surgery for patients with genetic refractory epilepsy: a systematic review

Aims. In recent years, many different DNA mutations underlying the development of refractory epilepsy have been discovered. However, genetic diagnostics are still not routinely performed during presurgical evaluation and reports on epilepsy surgery outcome for patients with genetic refractory epilepsy are limited. We aimed to create an overview of the literature on seizure outcome following epilepsy surgery in patients with different genetic causes of refractory epilepsy. Methods. We systematically searched PubMed and Embase prior to January 2017 and included studies describing treatment outcome following epilepsy surgery in patients with genetic causes of epilepsy. We excluded studies in which patients were described with epilepsy due to Tuberous Sclerosis Complex or Sturge‐Weber syndrome (since this extensive body of research has recently been described elsewhere) and articles in which surgery was aimed to be palliative. Results. We identified 24 eligible articles, comprising a total of 82 patients who had undergone surgery for (mainly childhood‐onset) refractory epilepsy due to 15 different underlying genetic causes. The success rate of surgery varied widely across these different genetic causes. Surgery was almost never effective in patients with epilepsy due to mutations in genes involved in channel function and synaptic transmission, whereas surgery was significantly more successful regarding seizure control in patients with epilepsy due to mutations in the mTOR pathway. Patients with a lesion on MRI tended to have higher seizure freedom rates than those who were MRI‐negative. Conclusion. Although the evidence is still scarce, this systematic review suggests that studying genetic variations in patients with refractory epilepsy could help guide the selection of surgical candidates.     

Seizure outcome after extratemporal epilepsy surgery in childhood

Aim The aim of the study was to describe seizure outcome following surgery for focal extratemporal epilepsy and identify factors associated with prolonged postsurgical freedom from seizures. Method In this retrospective cohort study, children with drug‐resistant focal extratemporal epilepsy were treated surgically and followed up in a single tertiary care centre between 1997 and 2008. Results Eighty children were identified for inclusion in the study (42 males, 38 females; median age 9y 1mo, range 3mo–18y 7mo). The aetiology was identified as focal cortical dysplasia (n=37), low‐grade tumour (n=22), tuberous sclerosis (n=9), or non‐specific (n=12). Children were followed for a median of 3 years 1 month (range 8mo–10y 7mo) after surgery. Overall, at last follow‐up, 50% of the children had been completely seizure free since surgery (Engel class Ia); of these 40 individuals, 15 had discontinued all antiepileptic drugs. Several presurgical factors were associated with a favourable outcome. However, after controlling for confounding factors, aetiology appeared to be the only determinant of long‐term seizure outcome as non‐specific lesion pathology was associated with seizure recurrence (hazard ratio 10.43; 95% confidence interval 3.26–33.39). Interpretation In 50% of cases, children with surgically treated drug‐resistant extratemporal epilepsies have an excellent long‐term outcome. The aetiology of the epileptogenic lesion appears to be the only significant determinant of surgical outcome in this population of children. It is difficult to correctly identify non‐specific pathology on presurgical magnetic resonance imaging.     

Outcomes of resective surgery in children and adolescents with focal lesional epilepsy: The experience of a tertiary epilepsy center

ObjectiveThis study aimed to investigate the efficacy of resective surgery in children with focal lesional epilepsy by evaluating the predictive value of pre- and postsurgical factors in terms of seizure freedom.MethodsThis study included 61 children aged between 2 and 18 years who were admitted to the pediatric video-EEG unit for presurgical workup. Each patient was evaluated with a detailed history, video-EEG, neuroimaging, and postsurgical outcomes according to Engel classification to predict postsurgical seizure freedom. All the possible factors including history, etiology, presurgical evaluation, surgical procedures, and postsurgical results were analyzed for their predictive value for postoperative seizure freedom.ResultsOf the 61 patients, 75% were diagnosed as having temporal lobe epilepsy (TLE), and 25% were diagnosed with extra-TLE. Two years after the surgery, 78.6% were seizure-free, of which 89% had TLE, and 50% had extra-TLE (p < 0.05). Patients were more likely to have a favorable outcome for seizure freedom if they had rare seizure frequency, focal EEG findings, and focal seizures; had a temporal epileptogenic zone; or had TLE and hippocampal sclerosis. On the other hand, patients were more likely to have unfavorable results for seizure freedom if they had younger age of seizure onset, frequent seizures before the surgery, a frontal or multilobar epileptogenic zone, secondarily generalized seizures, extra-TLE with frontal lobe surgery, or focal cortical dysplasia.SignificanceResective surgery is one of the most effective treatment methods in children with intractable epilepsy. A history of young age of seizure onset, frequent seizures before surgery, secondarily generalized seizures, a multilobar epileptogenic zone, frontal lobe surgery, and focal cortical dysplasia (FCD) are the most important predictive factors indicating that a patient would continue having seizures after surgery. On the other hand, focal seizure semiologies, temporal lobe localization, and hippocampal sclerosis indicate that a patient would have better results in terms of seizure freedom.     

Is streamlined evaluation of children for epilepsy surgery possible?

Background: The presurgical evaluation of children with intractable epilepsy includes evaluation by an experienced clinician, MRI, video EEG, and functional imaging techniques to localize seizure onset. However, the contributions of each investigation to surgical decision making has not been systematically assessed.
Method: Data used for decision on eligibility for surgery on 353 children was discussed at a presurgical multidisciplinary meeting and systematically recorded. The relationships between MRI, EEG, SPECT findings, and the probability of being offered epilepsy surgery were investigated retrospectively using a quick unbiased statistical tree (QUEST).
Results: Sixteen children were offered nonresective surgery. Of the remaining, 236 (70%) were offered resective surgery. The proportion of children with a localized lesion on MRI offered resective surgery was 92%[95% CI: 88 to 95%], and EEG telemetry did not modify decision making in this group (p < 0.001). In children with bilateral MRI changes or normal scan the probability of being offered resective surgery was 78% in those with localized ictal onset on EEG compared to 9% with nonlocalized EEG (p < 0.001). SPECT did not appear to systematically influence decision making in any group.
Conclusion: Children with medically intractable epilepsy and localized lesions on MRI may not necessarily need ictal EEG recordings or SPECT prior to offering resective surgery. More targeted use of EEG telemetry could allow more children with less obvious surgical targets to be investigated without increasing resources.     

Comparative role of neuropsychological testing in the presurgical evaluation of children with medically intractable epilepsies

Purpose

In the present study, we evaluated the preoperative demographic, clinical, and neuropsychological variables that could predict postoperative seizure outcome in a group of pediatric epileptic patients.

Materials and methods

We studied 40 consecutive pediatric patients, ages ranging from 6 to 16 years, that underwent resective surgery for the treatment of medically intractable epilepsy at the Clinical Hospital of Ribeirão Preto School of Medicine. We performed ictal electroencephalography (EEG), interictal EEG, magnetic resonance imaging (MRI), and a preoperative neuropsychological assessment in the presurgical workup.

Results

The following factors were correlated with seizure outcome: (1) duration of epilepsy, (2) surgery localization, (3) localized Neuropsychological (NPS) Evaluation, (4) ictal EEG, (5) interictal EEG, and (6) MRI. Mental retardation, NPS tests, and the other demographic variables failed to correlate with seizure reduction.

Conclusions

The identification of predictor variables of epilepsy surgery outcome could improve the epileptic prognosis and guarantee the children's full potential development.

     

External validation of the Epilepsy Surgery Grading Scale in a Japanese cohort of patients with epilepsy

Objective: The Epilepsy Surgery Grading Scale (ESGS) is a simple method to predict the likelihood of a patient with epilepsy proceeding to surgery and achieving seizure freedom. Usefulness of the ESGS has been confirmed in established epilepsy centres in the United States and Belgium for adult patients with drug‐resistant focal epilepsy undergoing presurgical evaluation. However, the applicability of the ESGS has not yet been evaluated in a wider range of epilepsy patients that may reflect the general spectrum of epilepsy. The present study validated the ESGS in a Japanese epilepsy centre in which admission‐based comprehensive epilepsy studies were indicated beyond presurgical evaluation. Methods: This single‐centre retrospective study included adult patients with epilepsy admitted to the Epilepsy Monitoring Unit from 2010 to June 2019. Patients were classified as ESGS Grade 1 (most favorable), Grade 2 (intermediate), and Grade 3 (least favourable). Patients were grouped into three cohorts: all patients, patients with drug‐resistant focal epilepsy, and patients who underwent resective epilepsy surgery. We assessed progression to surgery and seizure freedom at one year after surgery. Results: Of the 1,158 total admissions, 670 patients met the inclusion criteria and formed the total cohort. Of these, 435 (64.9%) had drug‐resistant focal epilepsy and 78 (11.6%) proceeded to resective surgery. Overall, progression to surgery was observed in 41.3%, 16.6%, and 4.8% of patients with Grade 1, 2, and 3, respectively. In the surgical cohort, seizure freedom was observed in 85.2%, 65.2%, and 31.3% of patients with Grade 1, 2, and 3, respectively. Significance: Our results indicate that the ESGS is effective in predicting whether a patient proceeds to epilepsy surgery and achieves seizure freedom even in the general population of epilepsy patients, regardless of type or resistance to antiepileptic drugs.     

Changing ictal-onset EEG patterns in children with cortical dysplasia

Purpose

Cortical dysplasia (CD) is intrinsically epileptogenic. We hypothesize that CDs clinically emerging in the early developing brain tend to extend into multifocal or larger epileptic networks to pronounce intractability in contrast to CDs which clinically emerge at a later age.

Methods

We evaluated the spatial and temporal profiles of ictal-onset EEG patterns in children with histopathologically confirmed CD. We designated Group A as children with changing ictal-onset EEG patterns over time, and Group B without change. We compared seizure profiles, consecutive scalp video-EEGs (VEEGs), MRI, MEG, and surgical outcomes.

Results

We found 14 children consisting of 10 Group A patients (7 girls) and 4 Group B patients (all boys). Eight (80%) Group A patients had their seizure onset < 5 years while all Group B patients had seizure onset ? 5 years (p < .05). Changes of ictal onset EEG pattern in Group A consisted of bilateral (4 patients), extending (2); extending and bilateral (2); and generalized (2). We saw MRI lesions (6) and single clustered MEG spike sources (MEGSSs) in (5). Six patients underwent surgery before 15 years of age, and 4 of them attained seizure freedom. All 4 Group B patients had MRI lesions and single clustered MEGSSs. Three patients underwent surgery after 15 years of age. All 4 patients attained seizure freedom.

Conclusion

Ictal-onset EEG patterns change over time in children with early seizure onset and intractable epilepsy caused by CD. Younger epileptic children with CD more frequently have multifocal epileptogenic foci or larger epileptogenic foci. Early resection of CD, guided by MRI, MEG, and intracranial video EEG, resulted in seizure freedom despite changes in ictal-onset EEG patterns.