Epilepsy Surgery Patients Research Articles

Cortical Dyplasia: Complete Resection Correlates with Outcome…But, Complete Resection of What?

Incomplete Resection of Focal Cortical Dysplasia Is the Main Predictor of Poor Postsurgical Outcome. Krsek P, Maton B, Jayakar P, Dean P, Korman B, Rey G, Dunoyer C, Pacheco-Jacome E, Morrison G, Ragheb J, Vinters HV, Resnick T, Duchowny M. Neurology 2009;72(3):217–223. BACKGROUND: Focal cortical dysplasia (FCD) is recognized as the major cause of focal intractable epilepsy in childhood. Various factors influencing postsurgical seizure outcome in pediatric patients with FCD have been reported. OBJECTIVE: To analyze different variables in relation to seizure outcome in order to identify prognostic factors for selection of pediatric patients with FCD for epilepsy surgery. METHODS: A cohort of 149 patients with histologically confirmed mild malformations of cortical development or FCD with at least 2 years of postoperative follow-up was retrospectively studied; 113 subjects had at least 5 years of postoperative follow-up. Twenty-eight clinical, EEG, MRI, neuropsychological, surgical, and histopathologic parameters were evaluated. RESULTS: The only significant predictor of surgical success was completeness of surgical resection, defined as complete removal of the structural MRI lesion (if present) and the cortical region exhibiting prominent ictal and interictal abnormalities on intracranial EEG. Unfavorable surgical outcomes are mostly caused by overlap of dysplastic and eloquent cortical regions. There were nonsignificant trends toward better outcomes in patients with normal intelligence, after hemispherectomy and with FCD type II. Other factors such as age at seizure onset, duration of epilepsy, seizure frequency, associated pathologies including hippocampal sclerosis, extent of EEG and MRI abnormalities, as well as extent and localization of resections did not influence outcome. Twenty-five percent of patients changed Engel's class of seizure outcome after the second postoperative year. CONCLUSIONS: The ability to define and fully excise the entire region of dysplastic cortex is the most powerful variable influencing outcome in pediatric patients with focal cortical dysplasia. FDG-PET/MRI Coregistration Improves Detection of Cortical Dysplasia in Patients with Epilepsy. Salamon N, Kung J, Shaw SJ, Koo J, Koh S, Wu JY, Lerner JT, Sankar R, Shields WD, Engel J Jr, Fried I, Miyata H, Yong WH, Vinters HV, Mathern GW. Neurology 2008;71(20):1594–1601. OBJECTIVE: Patients with cortical dysplasia (CD) are difficult to treat because the MRI abnormality may be undetectable. This study determined whether fluorodeoxyglucose (FDG)-PET/MRI coregistration enhanced the recognition of CD in epilepsy surgery patients. METHODS: Patients from 2004–2007 in whom FDG-PET/MRI coregistration was a component of the presurgical evaluation were compared with patients from 2000–2003 without this technique. For the 2004–2007 cohort, neuroimaging and clinical variables were compared between patients with mild Palmini type I and severe Palmini type II CD. RESULTS: Compared with the 2000–2003 cohort, from 2004–2007 more CD patients were detected, most had type I CD, and fewer cases required intracranial electrodes. From 2004–2007, 85% of type I CD cases had normal non–University of California, Los Angeles (UCLA) MRI scans. UCLA MRI identified CD in 78% of patients, and 37% of type I CD cases had normal UCLA scans. EEG and neuroimaging findings were concordant in 52% of type I CD patients, compared with 89% of type II CD patients. FDG-PET scans were positive in 71% of CD cases, and type I CD patients had less hypometabolism compared with type II CD patients. Postoperative seizure freedom occurred in 82% of patients, without differences between type I and type II CD cases. CONCLUSIONS: Incorporating fluorodeoxyglucose-PET/MRI coregistration into the multimodality presurgical evaluation enhanced the noninvasive identification and successful surgical treatment of patients with cortical dysplasia (CD), especially for the 33% of patients with nonconcordant findings and those with normal MRI scans from mild type I CD.

Bilateral and Independent Broca Areas Confirmed by Wada Test and Functional Magnetic Resonance Imaging

Accurate preoperative evaluation of language dominance is critical when evaluating potential patients for temporal lobe epilepsy surgery. Although most people have left-sided language dominance, a minority of patients have been described with either bilateral or right hemispheric dominance. We present a patient with right temporal lobe epilepsy who presented with bilateral and functionally independent Broca areas, as confirmed by Wada testing and functional magnetic resonance imaging.

Assessment and surgical outcomes for mild type I and severe type II cortical dysplasia: A critical review and the UCLA experience

Recent findings on the clinical, electroencephalography (EEG), neuroimaging, and surgical outcomes are reviewed comparing patients with Palmini type I (mild) and type II (severe) cortical dysplasia. Resources include peer-reviewed studies on surgically treated patients and a subanalysis of the 2004 International League Against Epilepsy (ILAE) Survey of Pediatric Epilepsy Surgery. These sources were supplemented with data from University of California, Los Angeles (UCLA). Cortical dysplasia is the most frequent histopathologic substrate in children, and the second most common etiology in adult epilepsy surgery patients. Cortical dysplasia patients present with seizures at an earlier age than other surgically treated etiologies, and 33-50% have nonlocalized scalp EEG and normal magnetic resonance imaging (MRI) scans. 2-((18)F)Fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) is positive in 75-90% of cases. After complete resection, 80% of patients are seizure free compared with 20% with incomplete resections. Compared with type I, patients with type II cortical dysplasia present at younger ages, have higher seizure frequencies, and are extratemporal. Type I dysplasia is found more often in adult patients in the temporal lobe and is often MRI negative. These findings identify characteristics of patients with mild and severe cortical dysplasia that define surgically treated epilepsy syndromes. The authors discuss future challenges to identifying and treating medically refractory epilepsy patients with cortical dysplasia.

Outcome of epilepsy surgery in patients investigated with subdural electrodes

Invasive intracranial electrodes (IE) are an important part of the work-up in many patients being considered for epilepsy surgery. Because IE are usually reserved for cases where seizure localization is ambiguous, one might expect that the eventual outcome of epilepsy surgery in these patients would be worse than in patients who did not require IE as part of their work-up. The purpose of this study was to specifically examine those patients who underwent insertion of subdural electrodes, to determine how many of these patients eventually underwent resective surgery of any type and to assess the eventual outcome. All cases admitted for subdural electrodes between January 2000 and June 2005 were reviewed. Surgical outcomes were reported using the Engel classification and a multivariate analysis was used to determine which factors were associated with successful surgery. 177 IE implantations were performed in 172 patients. Of these, 130 patients went on to have surgery. In the 113 of the 130 surgical patients in whom 1-year follow-up was available, 47% were seizure free at 1 year. Age was a major predictor of outcome with only 21% of patients over age 40 becoming seizure free with surgery compared to 58% in patients aged under 40 years (p=0.0004). Other predictors of an Engel I outcome included having a temporal lobectomy or supplementary motor area resection. Good results from eventual resective surgery can be achieved in patients needing invasive recordings. Younger patients with temporal lobe epilepsy seem to have the highest likelihood of seizure freedom.

Cortical neuronal loss and hippocampal sclerosis are not detected by voxel‐based morphometry in individual epilepsy surgery patients

Voxel‐based morphometry (VBM) has detected differences between brains of groups of patients with epilepsy and controls, but the sensitivity for detecting subtle pathological changes in single subjects has not been established. The aim of the study was to test the sensitivity of VBM using statistical parametric mapping (SPM5) to detect hippocampal sclerosis (HS) and cortical neuronal loss in individual patients. T1‐weighted volumetric 1.5 T MR images from 13 patients with HS and laminar cortical neuronal loss were segmented, normalised and smoothed using SPM5. Both modulated and non‐modulated analyses were performed. Comparisons of one control subject against the rest (n = 23) were first performed to ascertain the smoothing level with the lowest number of SPM changes in controls. Each patient was then compared against the whole control group. The lowest number of SPM changes in control subjects was found at a smoothing level of 10 mm full width half maximum for modulated and non‐modulated data. In the patient group, no SPM abnormalities were found in the affected temporal lobe or hippocampus at this smoothing level. At lower smoothing levels there were numerous SPM findings in controls and patients. VBM did not detect any abnormalities associated with either laminar cortical neuronal loss or HS. This may be due to normalisation and smoothing of images and low statistical power in areas with larger inter‐individual differences. This suggests that the methodology may currently not be suitable to detect particular occult abnormalities possibly associated with seizure onset zone in individual epilepsy patients with unremarkable standard structural MRI. Hum Brain Mapp, 2009. © 2009 Wiley‐Liss, Inc.

Increased activation of Iba1 + microglia in pediatric epilepsy patients with Rasmussen's encephalitis compared with cortical dysplasia and tuberous sclerosis complex

Microgliosis is prominent in Rasmussen's encephalitis (RE), a disease with severe seizure activity. However, it is unclear if microglial activation is similar with different histopathologic substrates. Iba1-immunolabelled microglial activation was assessed in neocortex from pediatric epilepsy surgery patients with RE ( n = 8), cortical dysplasia (CD; n = 6) and tuberous sclerosis complex (TSC; n = 6). Microglial reactivity was increased, in severely affected RE areas (29% labeling) compared with minimally affected areas of RE cases (15%) and cases of TSC (14%) and CD (12%). There was no qualitative association of Iba1 immunolabelling with the presence of CD8 + cytotoxic T-cells and no statistical association with clinical epilepsy variables, such as seizure duration or frequency. Iba1 appears to be an excellent marker for detecting extensive microglial activation in patients with RE. In addition, this study supports the notion that Iba1-labeled microglial activation is increased in patients with active RE, compared with cases of CD and TSC.

Epilepsy surgery in patients with multiple cerebral cavernous malformations

Purpose Cerebral cavernous malformations (CCMs) are frequently associated with intractable epilepsy. Whereas surgery indication in single CCMs is clear, data regarding the efficacy of epilepsy surgery in patients with multiple CCMs are scarce. We sought to clarify diagnostic requirements and postoperative outcome in patients with multiple CCMs and refractory epilepsy. Methods Retrospective analysis of clinical records of hospitalized patients who underwent comprehensive diagnostic work-up including long-term video-EEG monitoring. Results From a total of 63 consecutive patients with CCMs and medically refractory epilepsy, 11 (17%) had multiple CCMs and underwent epilepsy surgery. There were three females and eight males. Mean age at epilepsy onset was 28.3 years (S.D. 12.3), and at epilepsy surgery, 40.7 years (S.D. 10.3). On average, each patient had 3.7 (S.D. 2.2) supratentorial CCMs. In all cases we identified only one epileptogenic zone. The epileptogenicity was higher for the CCMs located within the temporal lobe. At 2 years follow-up, the outcome according to the Engel classification was Ia (seizure-free) in nine patients (81.8%) and IIb (rare seizures) and IVc (worsening) in two patients, respectively. In one patient, a dual pathology was present and, in another case, de novo appearance of CCMs was demonstrated. Conclusions Our results show that postoperative outcome in patients with multiple CCMs can be as good as in those with single malformations if proper presurgical identification of the epileptogenic CCMs is done. The possibility of the novo appearance of CCMs or dual pathology may occur and may affect long-term outcome negatively.

Epilepsy surgery patients with cortical dysplasia

Cortical dysplasia is the most common substrate in pediatric and the second or third most frequent etiology in adult epilepsy surgery patients.1 The histopathology was first described less than 30 years ago,2 and we are still learning about the clinical features of this disorder. Early surgical series involved few patients or focused on MRI positive cases,3,4 and reported inconsistent predictors of therapeutic success. Only recently have single centers published surgical cohorts of over 100 patients.5,6 This issue of Neurology® publishes two studies that together report on 315 epilepsy surgery patients with cortical dysplasia: Krsek et al., a mostly pediatric cohort from Miami Children's Hospital, and Kim et al., a generally adult population from Seoul, Korea.7,8 Both centers have previously published on their cohorts.9,10 From these and other reports emerges a clearer image of the electro-clinico-pathologic characteristics of patients with cortical dysplasia. For example, most surgical patients have mild compared with severe forms of cortical dysplasia on histopathology. This is defined as mild malformations of cortical development (mMCD; 16%) or mild type I (59%) cortical dysplasia using the Palmini classification system …

Is Seizure Surgery an Option for Patients with Very Low IQ?

Seizure Outcome after Resective Epilepsy Surgery in Patients with Low IQ. Malmgren K, Olsson I, Engman E, Flink R, Rydenhag B. Brain 2008;131(Pt 2):535–542. Epilepsy surgery has been questioned for patients with low IQ, since a low cognitive level is taken to indicate a widespread disturbance of cerebral function with unsatisfactory prognosis following resective surgery. The prevalence of epilepsy in patients with cognitive dysfunction is, however, higher than in the general population and the epilepsy is often more severe and difficult to treat. It is therefore important to try to clarify whether IQ predicts seizure outcome after resective epilepsy surgery. The Swedish National Epilepsy Surgery Register, which includes data on all epilepsy surgery procedures in Sweden since 1990, was analysed for all resective procedures performed 1990–99. Sustained seizure freedom with or without aura at the 2-year follow-up was analysed as a function of pre-operative IQ level categorized as IQ <50, IQ 50–69 and IQ ≥70 and was also adjusted for the following variables: age at epilepsy onset, age at surgery, pre-operative seizure frequency, pre-operative neurological impairment, resection type and histopathological diagnosis. Four hundred and forty-eight patients underwent resective epilepsy surgery in Sweden from 1990 to 1999 and completed the 2-year follow-up: 72 (16%) had IQ <70, (18 with IQ <50 and 54 with IQ 50–69) and 376 IQ ≥70. There were 313 adults and 135 children ≤18 years. Three hundred and twenty-five patients underwent temporal lobe resections (TLR) and 123 underwent various extratemporal resections (XTLR). At the 2-year follow-up, 56% (252/448) of the patients were seizure free: 22% (4/18) in the IQ <50 group, 37% (20/54) in the IQ 50–69 group and 61% (228β76) in the IQ ≥70 group. There was a significant relation between IQ category and seizure freedom [odds ratio (OR) 0.41, 95% confidence interval (CI) 0.27–0.62] and this held also when adjusting for clinical variables [OR 0.58 (95% CI 0.35–0.95)]. In this population-based epilepsy surgery series, IQ level was shown to be an independent predictor of seizure freedom at the 2-year follow-up. However, many of the low-IQ patients benefit from surgery, especially patients with lesions. Low IQ should not exclude patients from resective epilepsy surgery, but is an important prognostic factor to consider in the counselling process.

Pyramidal cell responses to γ‐aminobutyric acid differ in type I and type II cortical dysplasia

Abnormalities in the gamma-aminobutyric acid (GABA)-ergic system could be responsible for seizures in cortical dysplasia (CD). We examined responses of pyramidal neurons to exogenous application of GABA, as well as alterations of GABAergic interneuron number and size in pediatric epilepsy surgery patients with non-CD, type I CD, and type II CD pathologies. We used the dissociated cell preparation for electrophysiology along with immunohistochemistry to identify number and size of GABAergic cells. Pyramidal neurons from type I CD tissue showed increased EC(50) and faster kinetics compared with cells from non-CD and type II CD tissue. Cytomegalic pyramidal neurons showed increased GABA peak currents and decreased peak current densities, longer kinetics, and decreased sensitivity to zolpidem and zinc compared with normal pyramidal cells from non-CD and type I CD. There were fewer but larger glutamic acid decarboxylase (GAD)-containing cells in type II CD tissue with cytomegalic neurons compared with non-CD, type I CD, and type II CD without cytomegalic neurons. In addition, GABA transporters (VGAT and GAT-1) showed increased staining surrounding cytomegalic neurons in type II CD tissue. These results indicate that there are differences in GABA(A) receptor-mediated pyramidal cell responses in type I and type II CD. Alterations in zolpidem and zinc sensitivities also suggest that cytomegalic neurons have altered GABA(A) receptor subunit composition. These findings support the hypothesis that patients with type I and type II CD will respond differently to GABA-mediated antiepileptic drugs and that cytomegalic neurons have features similar to immature neurons with prolonged GABA(A) receptor open channel times.

Functional imaging: II. Prediction of epilepsy surgery outcome

To gain information on the value of magnetic source imaging (MSI), 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET), and ictal single photon emission computed tomography (SPECT) to predict seizure-free outcome following epilepsy surgery in patients who require intracranial electroencephalography (ICEEG). This work was part of a prospective observation study of epilepsy surgery candidates not sufficiently localized with scalp EEG and MRI. Of 160 patients enrolled 62 completed ICEEG and subsequent surgical resection. Sixty-one percent resulted in an Engel I seizure-free outcome at a minimum of one-year follow-up (mean = 3.4 years). Sensitivity, specificity, and predictive values were computed for each modality. Multivariate logistical regression was used to identify prediction of surgical outcome by imaging test. MSI sensitivity for a conclusively localized study was 55% with a positive predictive value of 78%. Eliminating non-diagnostic MSI cases (no spikes captured during recording) yielded a corrected negative predictive value of 64%. With available comparison subgroups FDG-PET and ictal SPECT values were similar to MSI. The OR (adjusted for epilepsy and MRI classification) for MSI prediction of seizure-free outcome was 4.4 (p =0.01). In cases with both PET and MSI, the adjusted OR for PET was 7.1 (p <0.01) and for MSI was 6.4 (p = 0.01). In the cases with all three tests (n = 27), ictal SPECT had the highest OR of 9.1 (p = 0.05). MSI, FDG-PET, and ictal SPECT each have clinical value in predicting seizure-free surgical outcome in epilepsy surgery candidates who typically require ICEEG.

Different features of histopathological subtypes of pediatric focal cortical dysplasia

Focal cortical dysplasia (FCD) is the most frequent pathological finding in pediatric epilepsy surgery patients. Several histopathological types of FCD are distinguished. The aim of the study was to define distinctive features of FCD subtypes. We retrospectively reviewed clinical, electroencephalographic, magnetic resonance imaging, neuropsychological, and surgical variables, and seizure outcome data in 200 children. Cortical malformations were histopathologically confirmed in all patients, including mild malformation of cortical development type II (mMCD) in 36, FCD type Ia in 55, FCD type Ib in 39, FCD type IIa in 35, and FCD type IIb in 35 subjects. Perinatal risk factors were more frequent in mMCD/FCD type I than FCD type II. Children with FCD type IIb had more localized ictal electroencephalographic patterns and magnetic resonance imaging changes. Increased cortical thickness, abnormal gyral/sulcal patterns, gray/white matter junction blurring, and gray matter signal abnormality in fluid-attenuated inversion recovery and T2-weighted sequences occurred more often in FCD type II, were infrequent in FCD type I, and rare in mMCD. Lobar hypoplasia/atrophy was common in FCD type I. Hippocampal sclerosis was most frequent in FCD type I. Neuropsychological testing demonstrated no significant differences between the groups. There was a trend toward better surgical outcomes in FCD type II compared with FCD type I patients. Different histopathological types of mMCD/FCD have distinct clinical and imaging characteristics. The ability to predict the subtype before surgery could influence surgical planning. Invasive electroencephalographic study should be considered when mMCD/FCD type I is expected based on noninvasive tests.

Predictors of outcome after temporal lobectomy for refractory temporal lobe epilepsy

To identify predictors of outcome after epilepsy surgery in patients with temporal lobe epilepsy (TLE). Seventy-six patients with normal magnetic resonance imaging (MRI) or hippocampal sclerosis on MRI who underwent anterior temporal lobe resections were included. Outcome 2 years after surgery was classified as good (Engel I and II) or poor (Engel III and IV). Gender, age at onset and duration of epilepsy, history of febrile convulsions, auras, right- or left-sided TLE, memory ipsilateral to seizure onset (Wada test), hippocampal asymmetry (HA) and T2 relaxation time, amygdala, temporal lobe and hemispheral volume were tested for associations with outcome. Sixty-seven percent had a good outcome. Of all parameters tested, only a history of febrile convulsions and HA on quantitative MRI were significantly associated with a good seizure outcome. The absence of these parameters did not exclude a good outcome, but only five of 18 patients (28%) without HA and without a history of febrile convulsions had a good outcome. Febrile convulsions and HA were predictors of outcome after epilepsy surgery in TLE. Subtle volume loss in amygdala, temporal lobe or hemispheres and the memory ipsilateral to the side of resection were not associated with outcome.

A survey of neurologists’ views on epilepsy surgery and medically refractory epilepsy

There is a 20-year delay between the diagnosis of epilepsy and surgical treatment. The aim of this study was to describe the different views held by neurologists regarding refractory epilepsy that may contribute to the delay in referring patients for epilepsy surgery. Neurologists in Michigan were mailed a 10-item survey inquiring about their definition of medically refractory epilepsy and their decision-making process in referring patients for epilepsy surgery. Eighty-four neurologists responded (20%). The majority defined medically refractory epilepsy as failure of three monotherapy antiepileptic drug (AEDs) trials and at least two polytherapy trials. Nineteen percent responded that all approved AEDs had to fail before a patient could be defined as medically refractory. Eighty-two percent of the respondents had referred patients for epilepsy surgery. Almost 50% were not satisfied with the level of communication from epilepsy centers. One-third reported serious complications resulting from surgery. These findings suggest that further education and improved communication from comprehensive epilepsy centers may shorten the time to referral and ultimately improve the lives of patients with epilepsy.

LONG-TERM SEIZURES AND QUALITY OF LIFE AFTER EPILEPSY SURGERY COMPARED WITH MATCHED CONTROLS

We compared long-term seizure outcome and health-related quality of life (HRQoL) of patients who underwent epilepsy surgery and matched medically treated nonsurgical controls with intractable epilepsy. Medically treated controls were identified for patients operated on for epilepsy between January 1, 1949 and December 31, 1992. We used a matched cohort design, matching for age, sex, and seizure type. The analysis was based on 70 complete matching pairs. HRQoL was assessed with the Quality of Life in Epilepsy Inventory 89 questionnaire an average of 15 years after surgery. Among surgery patients, 48% were seizure-free during the previous year compared with 19% of the controls (P = 0.0004). Fewer surgery patients used antiepileptic drugs (70%) than controls (93%). The odds of being seizure-free were higher for surgery patients in total and in subgroups divided according to length of follow-up. The mean HRQoL for surgery patients was higher in five of the 17 Quality of Life in Epilepsy Inventory 89 dimensions and worse in none. Among patients with more than 7 years of follow-up, HRQoL was better in three dimensions and worse in none. Among patients with 7 years of follow-up or less, HRQoL was better in two dimensions and worse in the language dimension of the Quality of Life in Epilepsy Inventory 89. After an average of more than 15 years of follow-up, epilepsy surgery patients had fewer seizures, used less antiepileptic medication, and had better HRQoL in several dimensions of the Quality of Life in Epilepsy Inventory 89 instrument than matched medically treated controls with refractory epilepsy, although possibly at a slight disadvantage in the language dimension among those with 7 years of follow-up or less.

Is it worth pursuing surgery for epilepsy in patients with normal neuroimaging?

Is it worth pursuing surgery for epilepsy in patients with normal neuroimaging?

Functional localization of auditory cortical fields of human: Click-train stimulation

Averaged auditory evoked potentials (AEPs) to bilaterally presented 100 Hz click trains were recorded from multiple sites simultaneously within Heschl’s gyrus (HG) and on the posterolateral surface of the superior temporal gyrus (STG) in epilepsy-surgery patients. Three auditory fields were identified based on AEP waveforms and their distribution. Primary (core) auditory cortex was localized to posteromedial HG. Here the AEP was characterized by a robust polyphasic low-frequency field potential having a short onset latency and on which was superimposed a smaller frequency-following response to the click train. Core AEPs exhibited the lowest response threshold and highest response amplitude at one HG site with threshold rising and amplitude declining systematically on either side of it. The AEPs recorded anterolateral to the core, if present, were typically of low amplitude, with little or no evidence of short-latency waves or the frequency-following response that characterized core AEPs. We suggest that this area is part of a lateral auditory belt system. Robust AEPs, with waveforms demonstrably different from those of the core or lateral belt, were localized to the posterolateral surface of the STG and conform to previously described field PLST.

Seizure outcome after resective epilepsy surgery in patients with low IQ

Epilepsy surgery has been questioned for patients with low IQ, since a low cognitive level is taken to indicate a widespread disturbance of cerebral function with unsatisfactory prognosis following resective surgery. The prevalence of epilepsy in patients with cognitive dysfunction is, however, higher than in the general population and the epilepsy is often more severe and difficult to treat. It is therefore important to try to clarify whether IQ predicts seizure outcome after resective epilepsy surgery. The Swedish National Epilepsy Surgery Register, which includes data on all epilepsy surgery procedures in Sweden since 1990, was analysed for all resective procedures performed 1990-99. Sustained seizure freedom with or without aura at the 2-year follow-up was analysed as a function of pre-operative IQ level categorized as IQ <50, IQ 50-69 and IQ >or=70 and was also adjusted for the following variables: age at epilepsy onset, age at surgery, pre-operative seizure frequency, pre-operative neurological impairment, resection type and histopathological diagnosis. Four hundred and forty-eight patients underwent resective epilepsy surgery in Sweden from 1990 to 1999 and completed the 2-year follow-up: 72 (16%) had IQ <70, (18 with IQ <50 and 54 with IQ 50-69) and 376 IQ >or=70. There were 313 adults and 135 children <or=18 years. Three hundred and twenty-five patients underwent temporal lobe resections (TLR) and 123 underwent various extratemporal resections (XTLR). At the 2-year follow-up, 56% (252/448) of the patients were seizure free: 22% (4/18) in the IQ <50 group, 37% (20/54) in the IQ 50-69 group and 61% (228/376) in the IQ >or=70 group. There was a significant relation between IQ category and seizure freedom [odds ratio (OR) 0.41, 95% confidence interval (CI) 0.27-0.62] and this held also when adjusting for clinical variables [OR 0.58 (95% CI 0.35-0.95)]. In this population-based epilepsy surgery series, IQ level was shown to be an independent predictor of seizure freedom at the 2-year follow-up. However, many of the low-IQ patients benefit from surgery, especially patients with lesions. Low IQ should not exclude patients from resective epilepsy surgery, but is an important prognostic factor to consider in the counselling process.

Epilepsy surgery in patients with coexisting psychogenic nonepileptic seizures: diagnosis and treatment

The prevalence of epileptic seizures among patients with psychogenic nonepileptic seizures may range from five to fifty percent. Diagnosis of both conditions occurring in association may be difficult and requires both clinical skills and prolonged video-EEG monitoring. Occurrence of seemingly psychogenic events during video-EEG monitoring should be interpreted with caution, and the relative role of both psychogenic and epileptic seizures in day-to-day living should be carefully evaluated for each individual patient. Surgery is not contraindicated in this setting, however patients and family members should be educated about both conditions before surgical decision. Psychogenic seizures and other psychiatric co-morbidities should be properly assessed and treated before surgery. Diagnosis and management of postoperative events (epileptic or psychogenic) is challenging. This difficulty can be minimized by appropriate presurgical management, that includes diagnostic testing, neurologic and psychiatric treatment and patient and family counseling.

Defining the spectrum of international practice in pediatric epilepsy surgery patients

The Pediatric Epilepsy Surgery Sub-commission of the International League Against Epilepsy conducted a survey to determine the frequency of epilepsy procedures and etiologies. Data were gathered from 20 programs in the United States, Europe, and Australia on 543 patients (<18 years) for calendar year 2004. Age at seizure onset was 1 year or less in 46% of patients. Intracranial electrodes were used in 27% of patients. The most common final operation was lobar and focal resections of the frontal and temporal lobes (41%), followed by cerebral hemispherectomy (16%), vagus nerve stimulator (16%), and multilobar resections (13%). Multiple-subpial transections were uncommon procedures (0.6%). The most frequent etiologies were cortical dysplasia (42%), tumors (19%), and atrophic lesions and strokes (10%). Less common were vascular lesions (1.5%), Rasmussen encephalitis (3%), Sturge-Weber (3%), and operations for infantile spasms (4%), and Landau-Kleffner/ESES (<2%). Children <4 years generally presented with daily seizures from cortical dysplasia and underwent multilobar or hemispherectomy. Previous surgeries before 2004 were reported in 22%, and occurred more commonly in patients with tumors (40%), hypothalamic hamartomas (47%), and vascular lesions (67%). U.S. centers reported more vagus nerve stimulator procedures, operated more often on children with no or subtle MRI findings, and used intracranial electrodes and functional neuroimaging more frequently than programs in Europe and Australia. The results of this international survey show the feasibility of international collaborations in determining epilepsy etiologies and procedures in children, and suggest differences in clinical practice between regions of the world. These results can guide the design of future studies in producing guidelines for therapy-resistant pediatric epilepsy surgery patients.