Magnetoencephalography and ictal SPECT in patients with failed epilepsy surgery

Objective

Selected patients with intractable focal epilepsy who have failed a previous epilepsy surgery can become seizure-free with reoperation. Preoperative evaluation is exceedingly challenging in this cohort. We aim to investigate the diagnostic value of two noninvasive approaches, magnetoencephalography (MEG) and ictal single-photon emission computed tomography (SPECT), in patients with failed epilepsy surgery.

Utility of magnetoencephalography in the evaluation of recurrent seizures after epilepsy surgery

PURPOSE: To study the role of magnetoencephalography (MEG) in the surgical evaluation of children with recurrent seizures after epilepsy surgery. METHODS: We studied 17 children with recurrent seizures after epilepsy surgery using interictal and ictal scalp EEG, intracranial video EEG (IVEEG), MRI, and MEG. We analyzed the location and distribution of MEG spike sources (MEGSSs) and the relationship of MEGSSs to the margins of previous resections and surgical outcome. RESULTS: Clustered MEGSSs occurred at the margins of previous resections within two contiguous gyri in 10 patients (group A), extended spatially from a margin by < or =3 cm in three patients (group B), and were remote from a resection margin by >3 cm in six patients (group C). Two patients had concomitant group A and C clusters. Thirteen patients underwent second surgeries. IVEEG was used in four patients. Six of seven patients with group A MEGSS clusters did not require IVEEG for second surgeries. Follow-up periods ranged from 0.6 to 4.3 years (mean: 2.6 years). Eleven children, including eight who became seizure-free, achieved Engel class I or II. CONCLUSION: Our data demonstrate the utility of MEG for evaluating patients with recurrent seizures after epilepsy surgery. Specific MEGSS cluster patterns delineate epileptogenic zones. Removing cluster regions adjacent to the margins of previous resections, in addition to removing recurrent lesions, achieves favorable surgical outcome. Cluster location and extent identify which patients require IVEEG, potentially eliminating IVEEG for some. Patients with remotely located clusters require IVEEG for accurate assessment and localization of the entire epileptogenic zone.     

Estereoelectroencefalografía en la evaluación prequirúrgica de epilepsias focales refractarias: experiencia de un centro de epilepsia

ObjectiveStereoelectroencephalography (SEEG) is a technique for preoperative evaluation of patients with difficult-to-localise refractory focal epilepsy (DLRFE), enabling the study of deep cortical structures. The procedure, which is increasingly used in international epilepsy centres, has not been fully developed in Spain. We describe our experience with SEEG in the preoperative evaluation of DLRFE.Material and methodsIn the last 8 years, 71 patients with DLRFE were evaluated with SEEG in our epilepsy centre. We prospectively analysed our results in terms of localisation of the epileptogenic zone (EZ), surgical outcomes, and complications associated with the procedure.ResultsThe median age of the sample was 30 years (range, 4-59 years); 27 patients (38%) were women. Forty-five patients (63.4%) showed no abnormalities on brain MR images. A total of 627 electrodes were implanted (median, 9 electrodes per patient; range, 1-17), and 50% of implantations were multilobar. The EZ was identified in 64 patients (90.1%), and was extratemporal or temporal plus in 66% of the cases. Follow-up was over one year in 55 of the 61 patients undergoing surgery: in the last year of follow-up, 58.2% were seizure-free (Engel Epilepsy Surgery Outcome Scale class I) and 76.4% had good outcomes (Engel I-II). Three patients (4.2%) presented brain haemorrhages.ConclusionSEEG enables localisation of the EZ in patients in whom this was previously impossible, offering better surgical outcomes than other invasive techniques while having a relatively low rate of complications.     

Clinical phenotypes within non-surgical patients with mesial temporal lobe epilepsy caused by hippocampal sclerosis based on response to antiepileptic drugs

PurposeTo evaluate evolution and elucidate clinical phenotypes related to prognosis of patients with mesial temporal lobe epilepsy related to hippocampal sclerosis (MTLE-HS) treated exclusively with antiepileptic drugs (AED).MethodsForty-seven out of 68 MTLE-HS patients treated between January 2005 and June 2010 were retrospectively studied for demographic, clinical and outcome data. The population was divided into drug-responder and drug-resistant patients; the latter was divided, according to the duration of the seizure-free periods along their evolution, into patients with at least one seizure-free period longer than one year and those with shorter periods. Variables were compared between drug-responders vs drug-resistants and drug-resistants with long seizure-free periods vs drug-resistants without it.ResultsThere were 7 (15%) drug-responders, 39 (83%) drug-resistants and 1 patient (2%) with an undetermined response. Eighteen (46%) drug-resistant individuals had seizure-free periods longer than one year, with mean duration of 46 months (3.8 years). Since no factor was statistically associated with long seizure-free period within drug-resistants, we can clinically distinguish two phenotypes: women with left HS and late onset of seizures, with poor prognosis, and men with right HS and earlier appearance of seizures, attaining a better outcome. Twenty out of 47 (42.5%) patients followed an intermittent pattern of epilepsy.ConclusionsNon-surgical MTLE-HS drug-resistant patients can achieve long seizure-free periods with AED, but relapses are common. Female gender, left or bilateral lesion and later onset of seizures seem to be bad prognosis factors within MTLE-HS drug-resistant patients.     

Orbitofrontal epilepsy: Case series and review of literature

BackgroundOrbitofrontal epilepsy (OFE) is less known and is poorly characterized in comparison with temporal lobe epilepsy, partly because it is rare and possibly because it is unrecognized and therefore underestimated.ObjectiveThis paper aimed to better characterize seizure semiology, presurgical findings, and surgical outcomes in patients with OFE.MethodsWe retrospectively reviewed all confidently established OFE cases from six Canadian epilepsy monitoring units between 1988 and 2014, and in the literature between 1972 and 2017. Inclusion criteria were identification of an epileptogenic lesion localized in the OFC or if the patient was seizure-free after surgical removal of the OFC in nonlesional cases.ResultsSixteen cases were identified from our databases. Fifty percent had predominantly sleep-related seizures; 56% had no aura (the remaining had nonspecific or vegetative auras), and 62.5% featured hypermotor (mostly hyperkinetic) behaviors. Interictal epileptiform discharges over frontal and temporal derivations always allowed lateralization. Magnetic resonance imaging (MRI) identified an orbitofrontal lesion in 8/16, positron emission tomography (PET) identified a hypometabolism extending outside the orbital cortex in 4/9, ictal single-photon emission computed tomography (SPECT) identified an orbital hyperperfusion in 1/5, magnetoencephalography (MEG) identified lateral orbital sources in 2/4, and intracranial electroencephalography (EEG) identified an orbitofrontal onset in 9/10. Fourteen patients underwent surgery, all reaching a favorable outcome (71.4% Engel 1; 28.6% Engel 2; mean FU = 5.6 years). Pre- and postoperative neuropsychological assessments revealed heterogeneous findings. Our review of literature identified 71 possible cases of OFE, 32 with confident focus localization. Extracted data from these cumulated cases supported observations made from our case series.ConclusionsOrbitofrontal epilepsy should be suspected with sleep-related, hyperkinetic seizures with no specific aura, and frontotemporal interictal discharges. Several patients have nonmotor seizures with or without auras which may resemble temporal lobe seizures. Postoperative seizure outcome was favorable, but there is inherent bias as we only included patients with a seizure-free outcome if the MRI was negative. A larger study is required to address identified gaps in knowledge such as identifying discriminative features between medial and lateral OFE, evaluating the value of more recent diagnostic tools, and assessing the neuropsychological outcome of orbital epilepsy surgery.     

Retention rate of pregabalin in drug-resistant epilepsy: 1-year follow-up, single-centre observation in 105 consecutive, adult patients

ObjectivesPregabalin (PGB) is a newer antiepileptic drug (AED) licensed as add-on treatment for partial epilepsy in adults. Efficacy and safety have been proven in several controlled clinical studies. These trials, however, only partially reflect clinical practice. Retention rate has been established as a marker for efficacy and safety of AEDs in long-term follow-up studies.MethodsWe evaluated the data of the first 105 patients treated with PGB at Bethel Epilepsy Centre, a tertiary referral centre for epilepsy. The patients were interviewed after 3, 6 and 12 months.Results105 adult patients (aged 38 ± 13 years) were treated with PGB, on average in combination with 2.1 AEDs (mean observation period 232 days). 76.2% had focal epilepsy, 19.0 multifocal epilepsy, and 3.8% epilepsy with both focal and generalised seizures. 40% continued PGB with the following outcome: 5.7% seizure-free for at least 1 month (4.8% for at least 3 months, 2.4% for at least 6 months; one of the seizure-free patients, however, had had epilepsy surgery during the observational period), 17.1% responders (≥50% reduction of seizure frequency but not seizure-free), 13.3% with unchanged or increased seizure frequency. Reasons for withdrawal were lack of efficacy (47.6%) or side-effects (12.7%).ConclusionsPGB is a new therapeutic option as add-on therapy for patients with highly refractory focal epilepsies although the therapeutic success that can be expected in this group of patients is limited.     

Perisylvian vulnerability to postencephalitic epilepsy

ObjectivePostencephalitic epilepsy is often resistant to antiseizure medications, leading to evaluation for epilepsy surgery. Characterizing its localization carries implications for optimal surgical approach. We aimed to determine whether a prior history of encephalitis is associated with specific epileptogenic networks among patients with drug resistant epilepsy undergoing stereotactic EEG (SEEG).MethodsWe conducted a retrospective cohort study of drug resistant epilepsy, with and without a prior history of encephalitis. We analyzed SEEG recordings to identify patterns of seizure onset and organization. Seventeen patients with a history of encephalitis (of infectious etiology in two subjects) were identified from a database of patients undergoing SEEG and were compared to seventeen drug-resistant epilepsy controls without a history of encephalitis matched for confounding variables including pre-implantation hypotheses, epilepsy duration, age, and sex.ResultsIndependent bilateral seizures were noted in 65% of the postencephalitic epilepsy cohort. We identified four SEEG-ictal patterns in patients with a prior history of encephalitis: (1) anteromesial temporal onset (24%), (2) anteromesial temporal onset with early spread to the perisylvian region (29%), (3) perisylvian (59%) and (4) synchronized anteromesial temporal and perisylvian (29%) onsets. Patterns 3 and 4, with perisylvian involvement at onset, were unique to the encephalitis group (p = 0.0003 and 0.04 respectively) and exhibited a “patchwork” organization. None of the encephalitis patients vs 5/7 matched controls had Engel I outcome (p = 0.0048).ConclusionsPostencephalitic epilepsies involve anteromesial temporal and perisylvian networks, often in a bilateral independent manner. Unique ictal patterns involving the perisylvian regions was identified in the encephalitis group, but not in the matched control group. Significance: These findings may reflect a selective vulnerability of the perisylvian regions to epilepsy resulting from encephalitis, significantly mitigating the chances of success with SEEG-guided temporal resections.     

Ictal stereo-electroencephalography onset patterns of mesial temporal lobe epilepsy and their clinical implications

ObjectiveThe differences in mesial temporal epilepsy (MTE) stereo-electroencephalography (SEEG) seizure-onset patterns and their clinical implications remains unclear.MethodsWe analyzed consecutive patients with MTE undergoing non-invasive workup, SEEG evaluation and resective surgery. Cases were classified into either mesial temporal sclerosis (MTS) group or non-MTS group based on magnetic resonance imaging (MRI). Seizure-onset patterns of SEEG were classified to analyze their correlation with surgical outcome and clinical subtypes.ResultsTwenty-eight patients were studied. Twenty (71.4%) patients had Engel I outcome. Thirteen patients had one seizure-onset pattern, 15 had two or more patterns. Five patterns of seizure-onset were identified and seizure-onset zones differed significantly across the 5 patterns. No difference was observed in surgical outcome between patients with single or multiple seizure-onset patterns. Periodic spike-onset pattern was associated with MTS (P = 0.003) while burst-onset was associated with non-MTS lesions (P = 0.003). Patients with seizure-onsets outside the resected temporal lobe (multiple onsets) had poorer prognosis (P = 0.0046).ConclusionWe identified 5 distinct onset patterns of MTE and correlated two of them with MRI findings. Multiple seizure-onset patterns in MTE may not necessarily suggest poor outcome. Patients with multi-focal seizure-onsets including seizures originating outside the resected temporal lobe have poorer outcome.SignificanceThis study identifies distinct onset patterns of MTE and their clinical implications.     

Interictal spike localization for epilepsy surgery using magnetoencephalography beamforming

ObjectiveMagnetoencephalography (MEG) kurtosis beamforming is an automated localization method for focal epilepsy. Visual examination of virtual sensors, which are source activities reconstructed by beamforming, can improve performance but can be time-consuming for neurophysiologists. We propose a framework to automate the method and evaluate its effectiveness against surgical resections and outcomes.MethodsWe retrospectively analyzed MEG recordings of 13 epilepsy surgery patients who had one-year minimum post-operative follow-up. Kurtosis beamforming was applied and manual inspection was confined to morphological clusters. The region with the Maximum Interictal Spike Frequency (MISF) was validated against prospectively modelled sLORETA solutions and surgical resections linked to outcome.ResultsOur approach localized spikes in 12 out of 13 patients. In eight patients with Engel I surgical outcomes, beamforming MISF regions were concordant with surgical resection at overlap level for five patients and at lobar level for three patients. The MISF regions localized to spike onset and propagation modelled by sLORETA in two and six patients, respectively.ConclusionsAutomated beamforming using MEG can predict postoperative seizure freedom at the lobar level but tends to localize propagated MEG spikes.SignificanceMEG beamforming may contribute to non-invasive procedures to predict surgical outcome for patients with drug-refractory focal epilepsy.     

Insular and insulo-opercular epilepsy in childhood: An SEEG study

PurposeIn recent years, there have been series analysing the electro-clinical correlations of insular epilepsy in adult populations. In contrast, the ictal semiology in children with insular epilepsy is poorly described. Considering that early and successful surgery may greatly improve the cognitive outcome and quality of life, it is worthwhile to deepen our knowledge of insular epilepsy in children.MethodsWe retrospectively evaluated ten children with drug-resistant focal insular epilepsy who had been consecutively explored with stereoelectroencephalography (SEEG), followed by individually tailored resective surgery that included part of the insula in all cases. A detailed anatomo-electro-clinical analysis of non-invasive EEG and SEEG data was performed. At least one of the electrodes explored the insular cortex. SEEG analysis confirmed that the insular cortex was included in the ictal onset zone.ResultsEpilepsy onset was mostly during the first year of life, characterized by subtle seizures as well as spasms and myoclonic seizures. Later on, neurovegetative signs and asymmetric tonic and hypermotor seizures (HMS) dominated the ictal semiology. The epileptogenic zone was frequently wider than insular with frontal and central predominance. In eight patients, the tailored resection included a lesion. In seven patients, an Engel class 1 outcome as well as neuropsychological and behavioural improvement was obtained.ConclusionsSEEG is feasible and useful in children with drug-resistant insular epilepsy which is often characterized by autonomic symptoms as the initial symptoms and should be suspected in cases with HMS, asymmetric tonic seizures and even asymmetric spasms. Early propagation is mostly frontal and central. Analysis of a larger population is required to refine these findings.     

Functional hemispherectomy is safe and effective in adult patients with epilepsy

IntroductionFunctional hemispherectomy (FH) is a well-established therapeutic option for children with epilepsy with parenchymal damage confined to one hemisphere, yet its application in adults remains rare. The intention of our study was to investigate postoperative clinical and epileptological outcome in adults who received FH for intractable epilepsy.Materials and methodsWe retrospectively analyzed 12 adult patients (18–56 years) with intractable epilepsy due to unihemispheric pathology. All patients underwent FH. Postoperative neurological and cognitive outcome as well as seizure status were evaluated with a mean follow-up period of 4.9 years.ResultsTen patients (83%) were seizure-free (Engel I), and two (17%) had recurrent seizures at last follow-up. Apart from one patient requiring operative revision for bone flap infection, no perioperative morbidity or mortality occurred. Postoperative functional assessment revealed deterioration of motor function in 7 patients, whereas 5 remained unchanged. Language was unchanged in 8 patients. The absence of background slowing in preoperative electroencephalogram (EEG) as well as ictal and interictal EEG patterns located ipsilateral to the side of surgery was associated with favorable seizure outcome.ConclusionFavorable seizure control and acceptable functional outcome can be achieved by FH in adults with intractable epilepsy. The risk of postoperative deficits is moderate and even older patients are able to manage postoperative motor impairment. Therefore, FH should be considered in case of unihemispheric lesions also in adults.     

Factors predicting 10-year seizure freedom after temporal lobe resection

Background

Resective surgery is an established and evidence-based treatment approach in pharmacoresistant temporal lobe epilepsy (TLE). Extra-long-term follow-up data are important to allow for good patient counseling. So far, only few trials provide prospective or retrospective data exceeding 5 years.

Objective

This study aimed to present data of continuous seizure outcome over an extended time period, with a particular focus on patients who remained seizure free for 10 years.

Methods

We analyzed seizure outcome after epilepsy surgery for TLE in 46 consecutive patients, who were seen on an annual basis for 10 years in a single center (Epilepsy Center Berlin Brandenburg). Factors for remaining seizure free for 10 years were determined by univariate analysis.

Results

The class I outcome changed each year by 74–78%. Of the patients, 63% remained continuously in Engel class I (48% Engel Class IA for 10 years) for 10 years. Six patients were never seizure free (12.5%). After 10 years, 35% of the patients were cured (i.e., seizure-free without medication). A higher number of antiepileptic drugs and seizures before surgery as well as the indication for invasive presurgical monitoring were associated with “unsuccessful surgery.”

Conclusion

With almost half of the patients completely seizure free and more than a third “cured,” epilepsy surgery remains the mainstay of therapy for TLE patients. Analysis in larger cohorts with extra-long-term follow-up is needed to assess good prognostic factors and other postsurgical outcome issues such as neuropsychological, psychiatric, and psychosocial outcomes.

     

The effectiveness of cortico-cortical evoked potential in detecting seizure onset zones

Objective The aim of the study was to evaluate the parameters for localizing the seizure onset zone in refractory epilepsy patients using cortico-cortical evoked potentials (CCEP).

Methods Fifteen patients (nine females) with medically refractory partial epilepsy underwent stereo electro encephalography (SEEG) in Tsinghua University Yu-Quan Hospital from 2015 to 2016. Clinical semiology and, scalp electroencephalography (EEG) findings were analyzed during phase I preoperative evaluation. During phase II evaluation, localization of seizure onset zone (SOZ) was analyzed using SEEG by experienced epileptologists. Meanwhile, the cortico-cortical evoked potential (CCEP) paradigm was tested in all patients in phase II. The value of root-mean-square (RMS) of CCEPs amplitude from 7 ms to 300 ms after stimulation was analyzed to quantify the response.

Results RMS of CCEPs amplitude in SOZ was higher than in seizure propagation zone (SPZ) (P < 0.05) and non-seizure onset zone (NSOZ) (P < 0.05). RMS of CCEPs amplitude in SOZ was higher than in NSOZ in epilepsy patients with secondary generalized tonic-clonic seizures (SGTCS) (N = 6, P < 0.05); The RMS of CCEPs amplitude in SOZ was strikingly higher than SPZ in the repetitive spiking (RS) onset pattern, and the difference was significant (N = 5, P < 0.01).

Conclusions This data indicated that CCEP response is enhanced in SOZ despite different seizure types (with or without SGTCS). CCEP may be an effective method to locate SOZ.     

Clinical adult outcome 11–30 years after pediatric epilepsy surgery: Complications and other surgical adverse events,seizure control,and cure of epilepsy

Objective

Pediatric epilepsy surgery promises seizure freedom or even cure of epilepsy. We evaluated the long-term (≥10 years) adult clinical outcome including surgery-related adverse events and complications, which are generally underreported.

Methods

A monocentric, single-arm, questionnaire study in now adult patients who underwent epilepsy surgery during childhood. A novel ad hoc parental/patient questionnaire, which addressed diverse outcome domains was applied.

Results

From a total of 353 eligible patients, 203 could be contacted (3 patients died of causes unknown) and 101 (50%) returned appropriately filled-in surveys. No evidence for a survey-response bias was found. The rate of surgical complications according to the patient records was 9%. As regards the survey, half of the parents/patients reported surgical adverse events (expected and unexpected issues) and one-third reported permanent aversive sequels. Two-thirds of the patients were seizure-free during the last year before follow-up; 63% were Engel class 1A; favorable seizure outcomes (including auras only) were obtained in 73%; and 54% were seizure-free and off antiseizure medicine (ASM), that is, cured of epilepsy. In non–seizure-free patients, seizure relapse occurred at any time during the follow-up interval but 87% of those with a seizure-free first postoperative year were seizure-free at follow-up. One patient experienced a seizure relapse during the ASM withdrawal trial but became seizure-free again with ASMs. Eleven patients reported an increased number of ASMs as compared to the time before surgery. Earlier focal surgery did not affect the long-term clinical outcome.

Significance

Pediatric epilepsy surgery was capable of curing epilepsy in about one-half of the children and to significantly control seizures in about three-fourths. Long-term success of focal surgery did not depend on age at surgery or duration of epilepsy. Surgical adverse events including complications may be underreported and must be assessed more thoroughly.     

Intracranial EEG Seizure-Offset Termination Patterns: Relation to Outcome of Epilepsy Surgery in Temporal Lobe Epilepsy

Summary: Purpose: Studies using stereo-EEG (SEEG) and electrocorticography (ECoG) should not only identify a patient's epileptogenic zone, but also should provide prognostic information for surgical outcome. In this respect, seizure-offset patterns have so far been the subject of only one study, in which they were shown to be associated with poor outcome when recorded over cortical areas outside the temporal lobe of seizure onset. To clarify whether seizure-offset patterns are reliable in predicting seizure outcome, we studied SEEG/ECoG in a similar group of patients with temporal lobe epilepsy (TLE). Methods: SEEGECoG records of 44 patients with refractory TLE were analyzed. The areas of seizure termination were classified as ipsilateral or contralateral (mesial and/or lateral) temporal, (temporal and) frontal, and diffusehilateral. Patients were classified with respect to seizure outcome as either seizure-free (UCLA class la) or not seizure free (UCLA class 2–4); both groups were correlated with specific seizure-offset categories using Fisher's exact probability test and analysis of variance (ANOVA). Results: Of the 44 patients, the majority (n = 36) had at least part of their seizure offsets in the ipsilateral temporal lobe, whereas 8 patients manifested no seizure offsets in this lobe. Only 9 patients (20%) showed exclusive offsets in the ipsilateral temporal lobe. No statistically significant difference was evident between patients with all seizure offsets in the ipsilateral temporal lobe and those with offsets elsewhere. Similarly, no statistically significant difference was evident between patients with a diffuse seizure offset and those with seizure offsets of a different category. Conclusions: Seizure-offset patterns in SEEGECoG are unreliable in predicting seizure outcome after resective activity surgery for TLE.     

Outcomes after resective epilepsy surgery in patients over 50 years of age in Sweden 1990–2009 – A prospective longitudinal study

PurposeMost epilepsy surgery candidates are young adults. Outcome reports after epilepsy surgery in patients ≥50 years are few and varying. The aim of this study was to describe patient characteristics of older compared to younger adults and analyse seizure, complication and vocational outcomes in a large population-based series.MethodsWe analysed data from the Swedish National Epilepsy Surgery Register for 1990–2009 for patients ≥19 years at resective surgery who had completed two-year follow-up. Variables studied were seizure outcome, histo-pathological diagnoses, complications and vocational outcome. Data from patients ≥50 years and 19–49 years at surgery were compared.Results558 Adults underwent resective epilepsy surgery 1990–2009 and had two-year follow-up. 12% of the adults (67 patients) were ≥50 years at surgery. Patients ≥50 had longer epilepsy duration, more often had mesial sclerosis and less often had neurodevelopmental tumours and cortical malformations. The proportion of seizure-free patients at two-year follow-up did not differ between those ≥50 and 19–49 years (61% versus 61% seizure-free last year, 48% versus 43% completely seizure-free since surgery), neither did the occurrence of major complications (3% in both groups). The vocational situation was mainly stable between baseline and two-year follow-up in both groups, although older patients were less often employed than younger.Conclusion12% of adults in the Swedish series were ≥50 years at epilepsy surgery. Seizure outcome was as good for older as for younger adults, and there was no difference in the occurrence of major complications. This constitutes important information in the presurgical counselling process.     

Postsurgical outcome in patients with olfactory auras and drug-resistant epilepsy

ObjectivesWe investigated the clinical features associated with olfactory auras in patients with drug-resistant epilepsy and also hypothesized that this type of aura may predict worse postsurgical outcome in patients with drug-resistant temporal lobe epilepsy (TLE).MethodsIn this retrospective analysis, data from all patients with drug-resistant epilepsy who underwent epilepsy surgery were reviewed. Patients were prospectively registered in a database from 1986 through 2016. We assessed outcome in the first 5 years after surgery to produce a Kaplan–Meier estimate of seizure recurrence. Post-surgical outcome was classified into two groups; 1) seizure-free, with or without auras; or 2) relapse of complex partial or secondarily generalized seizures. We also investigated the clinical features of patients with TLE and olfactory auras compared with those without olfactory auras.ResultsWe studied 1186 patients. Thirty-seven patients (3.1%) reported olfactory auras with their seizures. Thirty-two patients had temporal lobe surgery. Intracranial video-EEG recording was performed in four patients. Three patients with lateral temporal neocortical seizures reported olfactory auras with their seizures; two of them were seizure-free after surgery. There were no significant clinical differences between patients with TLE and olfactory auras compared with those without. Seizure outcome after surgery was not significantly different between these two groups (p = 0.3; Cox–Mantel test).ConclusionThe rarity of olfactory auras makes it difficult to propose new diagnostic and treatment strategies. A multicenter approach, which can enroll more patients, is needed to devise better therapies for patients with drug-resistant epilepsy and this symptom.     

Seizure outcome after surgery for epilepsy due to malformation of cortical development

PURPOSE: To explore seizure outcome after surgery for focal epilepsy due to malformation of cortical development (MCD), with focus on the role of MRI. METHODS: Thirty-five patients who had surgery for intractable focal epilepsy due to MCD identified by preoperative MRI and confirmed by histopathologic analysis of resected tissue were studied. Patients were aged 3 months to 47 years (median, 14 years) at the time of surgery. Duration of follow-up was 1 to 7.9 (mean, 3.4) years. RESULTS: At latest follow-up, 17 patients (49%) had Engel Class I outcome with no seizures or auras only; eight patients (23%) had Class II outcome, with rare disabling seizures; seven patients (20%) had worthwhile improvement; and three patients (9%) had no improvement. Seizure-free outcome tended to be more frequent among patients who had complete resection of unilateral MCD (excluding hemimegalencephaly) based on postoperative MRI (7/12; 58%), compared with patients with unilateral MCD who had incomplete resection (3/11; 27%), but the difference was not significant. The frequency of seizure-free outcome did not differ significantly between children (8/14; 57%), adolescents (7/15; 47%) or adults (2/6; 33%); between patients who had daily (12/24; 50%), weekly (4/9; 44%), or monthly (1/2; 50%) seizures preoperatively; between patients who had temporal (2/6; 33%) or extratemporal or multilobar resections (14/28; 50%); or between patients who were (9/16; 56%) or were not (8/19; 42%) studied with subdural electrodes. Results for all analyses were similar when analyzed at latest available follow-up or at 1 year after surgery. CONCLUSIONS: Surgery can offer seizure-free outcome for approximately one half of carefully selected patients with intractable focal epilepsy due to MCD. Complete resection of the MRI-apparent lesion may improve the likelihood for favorable outcome. MRI evidence of hemimegalencephaly or bilateral MCD suggests a low likelihood for postoperative freedom from seizures.     

Prognostic factors in neocortical epilepsy surgery: multivariate analysis

PURPOSE: Defining prognostic factors for neocortical epilepsy surgery is important for the identification of ideal candidates and for predicting the prognosis of individual patients. We use multivariate analysis to identify favorable prognostic factors for neocortical epilepsy surgery. METHODS: One hundred ninety-three neocortical epilepsy patients, including 91 without focal lesions on MRI, were included. Sixty-one had frontal lobe epilepsy (FLE), 80 had neocortical temporal lobe epilepsy (nTLE), 21 had parietal lobe epilepsy (PLE), and 22 had occipital lobe epilepsy (OLE). The primary outcome variable was patient status >or=2 years after surgery (i.e., seizure free or not). Clinical characteristics and the recent presurgical diagnostic modalities were considered as probable prognostic factors. Univariate and standard multiple logistic regression analyses were used to identify favorable prognostic factors. RESULTS: The seizure-free rate was 57.5%. By univariate analysis, a focal lesion on MRI, localized ictal onset on surface EEG, epilepsies other than FLE, localized hypometabolism on fluorodeoxyglucose-positron emission tomography (FDG-PET), and pathologies other than cortical dysplasia were significantly associated with a seizure-free outcome (p<0.05). Multivariate analysis revealed that a focal lesion on MRI (p=0.003), correct localization by FDG-PET (p=0.007), and localized ictal onset on EEG (p=0.01) were independent predictors of a good outcome. CONCLUSIONS: The presence of a focal lesion on MRI, correct localized hypometabolism on FDG-PET, or localized ictal rhythms on EEG were identified as predictors of a seizure-free outcome. Our results suggest that these findings allow the selection of better candidates for neocortical epilepsy surgery.     

Neocortical temporal lobe epilepsy: intracranial EEG features and surgical outcome.

Patients with neocortical temporal lobe epilepsy (NTLE) may have less favorable outcome with anterior temporal lobectomy than those with mesial temporal foci. The authors analyzed ictal intracranial electroencephalograms (EEGs) in patients with NTLE to identify features that predict surgical outcome. The following intracranial ictal EEG features in 31 consecutive medically intractable NTLE patients were studied: Frequency (i.e., low-voltage fast [>20 Hz], recruiting ictal-onset spikes, ictal-onset rhythms less than 5 Hz, ictal-onset rhythms with repetitive sharp waves between 5 and 20 Hz); extent of ictal onset (focal, sublobar, and lobar); localization within the temporal lobe (anterior, posterior, or regional); and the time to seizure spread outside the temporal lobe (rapid, intermediate, and slow). The average follow-up period was 36.7 months (range, 18 to 60 months). Findings between two outcome groups were compared: class I group (seizure-free) and class II to IV group (persistent seizures). Twenty-one (66.7%) of 31 patients with NTLE were seizure-free. Intracranial EEG features which were significantly associated with seizure-free outcome were focal or sublobar onset, anterior temporal onset, and slow propagation time (P < 0.05). There was a trend for patients with ictal onset morphologies of slow ictal-onset rhythm and repetitive sharp waves to be seizure-free (P = 0.07). Intracranial EEG is helpful in predicting surgical outcome in NTLE patients.