Role of concordance between ictal-subtracted SPECT and PET in predicting long-term outcomes after epilepsy surgery

Predictive factors for seizure freedom after epilepsy surgery for pediatric low-grade tumors and focal cortical dysplasia

Epilepsy may be drug-resistant in a third of patients necessitating alternative treatments, such as surgery. Among refractory epilepsy patients, the most common etiologies are tumors and focal cortical dysplasia (FCD). Surgical management of tumor-related epilepsy has one of the highest rates of seizure freedom, whereas FCD represents some of the lowest success rates in epilepsy treatment. This study investigates the pre-operative characteristics associated with differences in postsurgical seizure outcomes in patients with FCD and tumors. We completed a retrospective cross-sectional review of epilepsy surgery patients with tumors (n = 29) or FCD (n = 44). Participants had a minimum medical follow-up at least 6 months after surgery (FCD M = 2.1 years; Tumors M = 2.0 years). Patients with FCD trended toward an earlier age of onset (t = -4.19, p = 0.058) and longer epilepsy duration (t = 3.75, p < 0.001). Epilepsy surgery is highly effective in reducing seizures in patients with FCD or tumors with over 70 % of all patients achieving seizure freedom. We found a higher rate of seizure freedom in patients with tumors than FCD, but this difference did not reach significance (79 vs. 66 %). Predictive factors of outcomes for FCD and tumors differ. Findings indicate that diagnostic tests may be differentially sensitive to patients with tumors, and future research is needed.

Periodic cycles of seizure clustering and suppression in children with epilepsy strongly suggest focal cortical dysplasia

AIM

We investigated characteristic seizure patterns in epilepsy caused by focal cortical dysplasia (FCD), which differ from epilepsy by other aetiologies in surgical cases with lesions on magnetic resonance imaging (MRI), then examined if these features were applicable to patients with epilepsy without any lesions on MRI.

METHOD

We retrospectively studied clinicopathological features in 291 (143 females) children with epilepsy who had undergone resective surgery after comprehensive evaluation, including 277 cases with lesions on MRI (136 females, age at resection 0-17 years [mean 6 years 10 months, SD 5 years 7 months]) and 14 cases without any lesions on MRI (seven females, age 0-16 years [mean 7 years 8 months, SD 4 years 8 months]).

RESULTS

Among 277 patients with lesions on MRI, 87 cases exhibited recurrent periodic cycles of seizure clustering (≥5 seizures/day for ≥1 week) and suppression (no seizures for ≥1 week); of these, 80 cases (92%) were pathologically diagnosed with FCD. Other pathologies included glial scar, hippocampal sclerosis, hemimegalencephaly, and cortical tuber in three, two, one, and one case respectively. All 14 patients without any lesions on MRI had significant recurrent periodic seizure cycles and FCD histopathologically.

INTERPRETATION

Periodic seizure cycles characterized by clustering and suppression in patients with epilepsy strongly suggest the presence of FCD regardless of MRI findings, and comprehensive evaluations for epilepsy surgery should be proceeded.

Suppressing interferences of EIT on synchronous recording EEG based on comb filter for seizure detection

Background and objective

The purpose of this study was to eliminate the interferences of electrical impedance tomography (EIT) on synchronous recording electroencephalography (EEG) for seizure detection.

Methods

The simulated EIT signal generated by COMSOL Multiphysics was superimposed on the clinical EEG signal obtained from the CHB-MIT Scalp EEG Database, and then the spectrum features of superimposed mixed signals were analyzed. According to the spectrum analysis, in addition to high-frequency interference at 51.2 kHz related to the drive current, there was also low-frequency interference caused by switching of electrode pairs, which were used to inject drive current. A low pass filter and a comb filter were used to suppress the high-frequency interference and low-frequency interference, respectively. Simulation results suggested the low-pass filter and comb filter working together effectively filtered out the interference of EIT on EEG in the process of synchronous monitoring.

Results

As a result, the normal EEG and epileptic EEG could be recognized effectively. Pearson correlation analysis further confirmed the interference of EIT on EEG was effectively suppressed.

Conclusions

This study provides a simple and effective interference suppression method for the synchronous monitoring of EIT and EEG, which could be served as a reference for the synchronous monitoring of EEG and other medical electromagnetic devices.

Spatial normalization and quantification approaches of PET imaging for neurological disorders

Quantification approaches of positron emission tomography (PET) imaging provide user-independent evaluation of pathophysiological processes in living brains, which have been strongly recommended in clinical diagnosis of neurological disorders. Most PET quantification approaches depend on spatial normalization of PET images to brain template; however, the spatial normalization and quantification approaches have not been comprehensively reviewed. In this review, we introduced and compared PET template-based and magnetic resonance imaging (MRI)-aided spatial normalization approaches. Tracer-specific and age-specific PET brain templates were surveyed between 1999 and 2021 for ¹⁸F-FDG, ¹¹C-PIB, ¹⁸F-Florbetapir, ¹⁸F-THK5317, and etc., as well as adaptive PET template methods. Spatial normalization-based PET quantification approaches were reviewed, including region-of-interest (ROI)-based and voxel-wise quantitative methods. Spatial normalization-based ROI segmentation approaches were introduced, including manual delineation on template, atlas-based segmentation, and multi-atlas approach. Voxel-wise quantification approaches were reviewed, including voxel-wise statistics and principal component analysis. Certain concerns and representative examples of clinical applications were provided for both ROI-based and voxel-wise quantification approaches. At last, a recipe for PET spatial normalization and quantification approaches was concluded to improve diagnosis accuracy of neurological disorders in clinical practice.

Multimodal Image Integration for Epilepsy Presurgical Evaluation: A Clinical Workflow

Multimodal image integration (MMII) is a promising tool to help delineate the epileptogenic zone (EZ) in patients with medically intractable focal epilepsies undergoing presurgical evaluation. We report here the detailed methodology of MMII and an overview of the utility of MMII at the Cleveland Clinic Epilepsy Center from 2014 to 2018, exemplified by illustrative cases. The image integration was performed using the Curry platform (Compumedics Neuroscan^™, Charlotte, NC, USA), including all available diagnostic modalities such as Magnetic resonance imaging (MRI), Positron Emission Tomography (PET), single-photon emission computed tomography (SPECT) and Magnetoencephalography (MEG), with additional capability of trajectory planning for intracranial EEG (ICEEG), particularly stereo-EEG (SEEG), as well as surgical resection planning. In the 5-year time span, 467 patients underwent MMII; of them, 98 patients (21%) had a history of prior neurosurgery and recurring seizures. Of the 467 patients, 425 patients underwent ICEEG implantation with further CT co-registration to identify the electrode locations. A total of 351 patients eventually underwent surgery after MMII, including 197 patients (56%) with non-lesional MRI and 223 patients (64%) with extra-temporal lobe epilepsy. Among 269 patients with 1-year post-operative follow up, 134 patients (50%) had remained completely seizure-free. The most common histopathological finding is focal cortical dysplasia. Our study illustrates the usefulness of MMII to enhance SEEG electrode trajectory planning, assist non-invasive/invasive data interpretation, plan resection strategy, and re-evaluate surgical failures. Information presented by MMII is essential to the understanding of the anatomo-functional-electro-clinical correlations in individual cases, which leads to the ultimate success of presurgical evaluation of patients with medically intractable focal epilepsies.

Role of Neuromodulation for Treatment of Drug-Resistant Epilepsy

The choice of neuromodulation techniques has greatly increased over the past two decades. While vagal nerve stimulation (VNS) has become established, newer variations of VNS have been introduced. Following the SANTE's trial, deep brain stimulation (DBS) is now approved for clinical use. In addition, responsive neurostimulation (RNS) has provided exciting new opportunities for treatment of drug-resistant epilepsy. While neuromodulation mostly offers only a 'palliative' measure, it still provides a significant reduction of frequency and intensity of epilepsy. We provide an overview of all the techniques of neuromodulation which are available, along with long-term outcomes. Further research is required to delineate the exact mechanism of action, the indications and the stimulation parameters to extract the maximum clinical benefit from these techniques.

Potential surgical therapies for drug-resistant focal epilepsy

Drug-resistant focal epilepsy (DRFE), defined by failure of two antiepileptic drugs, affects 30% of epileptic patients. Epilepsy surgeries are alternative options for this population. Preoperative evaluation is critical to include potential candidates, and to choose the most appropriate procedure to maximize efficacy and simultaneously minimize side effects. Traditional procedures involve open skull surgeries and epileptic focus resection. Alternatively, neuromodulation surgeries use peripheral nerve or deep brain stimulation to reduce the activities of epileptogenic focus. With the advanced improvement of laser-induced thermal therapy (LITT) technique and its utilization in neurosurgery, magnetic resonance-guided LITT (MRgLITT) emerges as a minimal invasive approach for drug-resistant focal epilepsy. In the present review, we first introduce drug-resistant focal epilepsy and summarize the indications, pros and cons of traditional surgical procedures and neuromodulation procedures. And then, focusing on MRgLITT, we thoroughly discuss its history, its technical details, its safety issues, and current evidence on its clinical applications. A case report on MRgLITT is also included to illustrate the preoperational evaluation. We believe that MRgLITT is a promising approach in selected patients with drug-resistant focal epilepsy, although large prospective studies are required to evaluate its efficacy and side effects, as well as to implement a standardized protocol for its application.

ACR Appropriateness Criteria® Seizures-Child

In children, seizures represent an extremely heterogeneous group of medical conditions ranging from benign cases, such as a simple febrile seizure, to life-threatening situations, such as status epilepticus. Underlying causes of seizures also represent a wide range of pathologies from idiopathic cases, usually genetic, to a variety of acute and chronic intracranial or systemic abnormalities. This document discusses appropriate utilization of neuroimaging tests in a child with seizures. The clinical scenarios in this document take into consideration different circumstances at the time of a child's presentation including the patient's age, precipitating event (if any), and clinical and electroencephalogram findings and include neonatal seizures, simple and complex febrile seizures, post-traumatic seizures, focal seizures, primary generalized seizures in a neurologically normal child, and generalized seizures in neurologically abnormal child. This practical approach aims to guide clinicians in clinical decision-making and to help identify efficient and appropriate imaging workup. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Surgical outcome and prognostic factors in epilepsy patients with MR-negative focal cortical dysplasia

Objective

Focal cortical dysplasia (FCD) represents a heterogeneous group of disorders of the cortical formation and is one of the most common causes of epilepsy. Magnetic resonance imaging (MRI) is the modality of choice for detecting structural lesions, and the surgical prognosis in patients with MR lesions is favorable. However, the surgical prognosis of patients with MR-negative FCD is unknown. We aimed to evaluate the long-term surgical outcomes and prognostic factors in MR-negative FCD patients through comprehensive presurgical data.

Methods

We retrospectively reviewed data from 719 drug-resistant epilepsy patients who underwent resective surgery and selected cases in which surgical specimens were pathologically confirmed as FCD Type I or II. If the epileptogenic focus and surgical specimens were obtained from brain areas with a normal MRI appearance, they were classified as MR-negative FCD. Surgical outcomes were evaluated at 2 and 5 years, and clinical, neurophysiological, and neuroimaging data of MR-negative FCD were compared to those of MR-positive FCD.

Results

Finally, 47 MR-negative and 34 MR-positive FCD patients were enrolled in the study. The seizure-free rate after surgery (Engel classification I) at postoperative 2 year was 59.5% and 64.7% in the MR-negative and positive FCD groups, respectively (p = 0.81). This rate decreased to 57.5% and 44.4% in the MR-negative and positive FCD groups (p = 0.43) at postoperative 5 years. MR-negative FCD showed a higher proportion of FCD type I (87.2% vs. 50.0%, p = 0.001) than MR-positive FCD. Unilobar cerebral perfusion distribution (odds ratio, OR 5.41) and concordance of interictal epileptiform discharges (OR 5.10) were significantly associated with good surgical outcomes in MR-negative FCD.

Conclusion

In this study, MR-negative and positive FCD patients had a comparable surgical prognosis, suggesting that comprehensive presurgical evaluations, including multimodal neuroimaging studies, are crucial for obtaining excellent surgical outcomes even in epilepsy patients with MR-negative FCD.

Impact of ictal subtraction SPECT and PET in presurgical evaluation

OBJECTIVE

To assess the relative contribution of ictal subtraction single-photon emission computed tomography (ISSPECT) and ¹⁸ F-fluorodeoxyglucose positron emission tomography computed tomography (PET) in epilepsy surgery decision making.

MATERIALS AND METHODS

A retrospective 3-year study of consecutive patients with resistant focal epilepsy who underwent ISSPECT and PET to evaluate to what extent these modalities influence decisions in epilepsy surgery and outcomes. ISSPECT imaging was performed in 106 patients and 58 (55%) had PET also. The clinical consensus (ClinC) was the final arbiter for decisions. Post-surgical outcomes were collected from follow-up clinics. Non-parametric statistics were used to assess association and logistic regression to evaluate prediction of outcomes.

RESULTS

Of 106 patients, 60 were males (57%). MRI was non-lesional in 46 (43%). Concordance with ClinC was seen in 80 patients (76%) for ISSPECT, in 46 patients (79%) for PET, and in 37 patients (64%) for ISSPECT + PET. Fifty-six patients (53%) were planned for intracranial video-electroencephalography monitoring (IVEM). Those with ClinC-PET concordance were likely to proceed to IVEM (p = 0.02). ClinC-PET concordance and ClinC-ISSPECT concordance did not predict decision to proceed to surgery, but VEM-MRI concordance did in lesional cases (p = 0.018). Forty-five (42%) underwent surgery of which 29 had minimum follow-up for 1 year (mean, 20 months; SD, 8) and 22 (76%) had Engel class I outcomes. ClinC-ISSPECT concordance (p = 0.024) and VEM-MRI concordance (p = 0.016) predicted Engel class I outcomes.

CONCLUSION

Those with ClinC-PET concordance were more likely to proceed with IVEM. ClinC-ISSPECT concordance and VEM-MRI concordance predicted good surgical outcomes.

Relative contribution of individual versus combined functional imaging studies in predicting seizure freedom in pediatric epilepsy surgery: an area under the curve analysis

OBJECTIVE

The goal of this study was to evaluate the predictive value and relative contribution of noninvasive presurgical functional imaging modalities based on the authors' institutional experience in pursuing seizure-free surgical outcomes in children with medically refractory epilepsy.

METHODS

This was a retrospective, single-institution, observational cohort study of pediatric patients who underwent evaluation and surgical treatment for medically refractory partial epilepsy between December 2003 and June 2016. During this interval, 108 children with medically refractory partial epilepsy underwent evaluation for localization and resective epilepsy surgery. Different noninvasive functional imaging modalities, including ictal SPECT, FDG-PET, and magnetoencephalography-magnetic source imaging, were utilized to augment a standardized paradigm (electroencephalography/semiology, MRI, and neuropsychology findings) for localization. Outcomes were evaluated at a minimum of 2 years (mean 7.5 years) utilizing area under the receiver operating characteristic curve analysis. Localizing modalities and other clinical covariates were examined in relation to long-term surgical outcomes.

RESULTS

There was variation in the contribution of each test, and no single presurgical workup modality could singularly and reliably predict a seizure-free outcome. However, concordance of presurgical modalities yielded a high predictive value. No difference in long-term outcomes between inconclusive (normal or diffusely abnormal) and abnormal focal MRI results were found. Long-term survival analyses revealed a statistically significant association between seizure freedom and patients with focal ictal EEG, early surgical intervention, and no history of generalized convulsions.

CONCLUSIONS

Comprehensive preoperative evaluation utilizing multiple noninvasive functional imaging modalities is not redundant and can improve pediatric epilepsy surgical outcomes.

Comparative contribution of magnetoencephalography (MEG) and single-photon emission computed tomography (SPECT) in pre-operative localization for epilepsy surgery: A prospective blinded study

PURPOSE

The aim of this study was to compare the diagnostic value and accuracy of ictal SPECT and inter-ictal magnetoencephalography (MEG) in localizing the site for surgery in persons with drug resistant epilepsy.

METHOD

This was a prospective observational study. Patients expected to undergo epilepsy surgery were enrolled consecutively and the localization results from different imaging modalities were discussed in an epilepsy surgery meet. Odds ratio of good outcome (Engel I) were calculated in patients who underwent surgery in concordance with MEG and SPECT findings. Post-surgical seizure freedom lasting at least 36 months or more was considered the gold standard for determining the diagnostic output of SPECT and MEG.

RESULTS

MEG and SPECT were performed in 101 and 57 patients respectively. In 45 patients SPECT could not be done due to delay in injection or technical factors. The accuracy of MEG and SPECT in localizing the epileptogenic zone was found to be 74.26 % and 78.57 % respectively. The diagnostic odds ratio for Engel I surgical outcome was reported as 2.43 and 5.0 for MEG and SPECT respectively. The diagnostic odds ratio for MEG in whom SPECT was non-informative was found to be 6.57 [95 % CI 1.1, 39.24], although it was not significantly associated with good surgical outcome. MEG was useful in indicating sites for SEEG implantation.

CONCLUSION

SPECT was found to be non-informative for most patients, but reported better diagnostic output than MEG. MEG may be a useful alternative for patients in whom SPECT cannot be done or was non-localizing.

Clinical Diagnosis and Perioperative Management of Glioma-Related Epilepsy

Gliomas account for more than half of all adult primary brain tumors. Epilepsy is the most common initial clinical presentation in gliomas. Glioma related epilepsy (GRE) is defined as symptomatic epileptic seizures secondary to gliomas, occurring in nearly 50% in high-grade glioma (HGG) patients and up to 90% in patients with low-grade glioma (LGG). Uncontrolled seizures, which have major impact on patients’ quality of life, are caused by multiple factors. Although the anti-seizure medications (ASMs), chemotherapy and radiation therapy are also beneficial for seizure treatment, the overall seizure control for GRE continue to be unsatisfactory. Due to the close relationship between GRE and glioma, surgical resection is often the treatment of choice not only for the tumor treatment, but also for the seizure control. Despite aggressive surgical treatment, there are about 30% of patients continue to have poor seizure control postoperatively. Furthermore, the diagnostic criteria for GRE is not well established. In this review, we propose an algorithm for the diagnosis and perioperative management for GRE.

High-quality brain perfusion SPECT images may be achieved with a high-speed recording using 360° CZT camera

Objective

The aim of this study was to compare brain perfusion SPECT obtained from a 360° CZT and a conventional Anger camera.

Methods

The 360° CZT camera utilizing a brain configuration, with 12 detectors surrounding the head, was compared to a 2-head Anger camera for count sensitivity and image quality on 30-min SPECT recordings from a brain phantom and from ^99mTc-HMPAO brain perfusion in 2 groups of 21 patients investigated with the CZT and Anger cameras, respectively. Image reconstruction was adjusted according to image contrast for each camera.

Results

The CZT camera provided more than 2-fold increase in count sensitivity, as compared with the Anger camera, as well as (1) lower sharpness indexes, giving evidence of higher spatial resolution, for both peripheral/central brain structures, with respective median values of 5.2%/3.7% versus 2.4%/1.9% for CZT and Anger camera respectively in patients (p < 0.01), and 8.0%/6.9% versus 6.2%/3.7% on phantom; and (2) higher gray/white matter contrast on peripheral/central structures, with respective ratio median values of 1.56/1.35 versus 1.11/1.20 for CZT and Anger camera respectively in patients (p < 0.05), and 2.57/2.17 versus 1.40/1.12 on phantom; and (3) no change in noise level. Image quality, scored visually by experienced physicians, was also significantly higher on CZT than on the Anger camera (+ 80%, p < 0.01), and all these results were unchanged on the CZT images obtained with only a 15 min recording time.

Conclusion

The 360° CZT camera provides brain perfusion images of much higher quality than a conventional Anger camera, even with high-speed recordings, thus demonstrating the potential for repositioning brain perfusion SPECT to the forefront of brain imaging.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40658-020-00334-7.

EEG lateralization and seizure outcome following peri-insular hemispherotomy for pediatric hemispheric epilepsy

OBJECTIVE

To determine whether preoperative non-lateralizing scalp electroencephalography (EEG) influences seizure outcome following peri-insular hemispherotomy (PIH) in pediatric hemispheric epilepsy.

METHODS

Retrospective data was collected on all 45 pediatric patients who underwent PIH between 2005 and 2016. All underwent a basic pre-surgical evaluation consisting of detailed history and examination, neuropsychological assessment, MRI, and EEG. SPECT/PET, fRMI, or Wada testing were done in only eight patients. Seizure outcome was assessed using the Engel classification.

RESULTS

Among those who underwent hemispherotomy, 20 (44%) were females. Mean age at surgery was 8 ± 4.3 years and mean duration of symptoms was 5.2 ± 3.7 years. The most common etiologies of hemispheric epilepsy were hemiconvulsion-hemiplegia epilepsy syndrome, Rasmussen encephalitis, and post-encephalitic sequelae, together comprising 27 (60%) patients. Among the 44 patients with follow-up data (mean duration 48 ± 33 months), seizure freedom (Engel class I) was attained by 41 (93.2%). Anti-epileptic medications were stopped or decreased in 36 (82%). Seventeen (38.6%) patients had non-lateralizing EEG. Seizure outcome was not related to lateralization of EEG activity.

CONCLUSIONS

PIH provides excellent long-term seizure control in patients despite the presence of non-lateralizing epileptiform activity, although occurrence of acute postoperative seizures may be higher. Routine SPECT/PET may not be required in patients with a non-lateralizing EEG if there is good clinico-radiological concordance.

Clinical practice guidelines for the diagnosis and treatment of adult diffuse glioma-related epilepsy

BACKGROUND

Glioma-related epilepsy (GRE) is defined as symptomatic epileptic seizures secondary to gliomas, it brings both heavy financial and psychosocial burdens to patients with diffuse glioma and significantly decreases their quality of life. To date, there have been no clinical guidelines that provide recommendations for the optimal diagnostic and therapeutic procedures for GRE patients.

METHODS

In March 2017, the Joint Task Force for GRE of China Association Against Epilepsy and Society for Neuro-Oncology of China launched the guideline committee for the diagnosis and treatment of GRE. The guideline committee conducted a comprehensive review of relevant domestic and international literatures that were evaluated and graded based on the Oxford Centre for Evidence-Based Medicine Levels of Evidence, and then held three consensus meetings to discuss relevant recommendations. The recommendations were eventually given according to those relevant literatures, together with the experiences in the diagnosis and treatment of over 3000 GRE cases from 24 tertiary level hospitals that specialize in clinical research of epilepsy, glioma, and GRE in China.

RESULTS

The manuscript presented the current standard recommendations for the diagnostic and therapeutic procedures of GRE.

CONCLUSIONS

The current work will provide a framework and assurance for the diagnosis and treatment strategy of GRE to reduce complications and costs caused by unnecessary treatment. Additionally, it can serve as a reference for all professionals involved in the management of patients with GRE.

Epileptogenic Zone Localization With 18FDG PET Using a New Dynamic Parametric Analysis

Introduction: [¹⁸F]fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) is part of the regular preoperative work-up in medically refractory epilepsy. As a complement to visual evaluation of PET, statistical parametric maps can help in the detection of the epileptogenic zone (EZ). However, software packages currently available are time-consuming and little intuitive for physicians. We develop a user-friendly software (referred as PET-analysis) for EZ localization in PET studies that allows dynamic real-time statistical parametric analysis. To evaluate its performance, the outcome of PET-analysis was compared with the results obtained by visual assessment and Statistical Parametric Mapping (SPM). Methods: Thirty patients with medically refractory epilepsy who underwent presurgical ¹⁸F-FDG PET with good post-operative outcomes were included. The ¹⁸F-FDG PET studies were evaluated by visual assessment, with SPM8 and PET-analysis. In SPM, parametric T-maps were thresholded at corrected p < 0.05 and cluster size k = 50 and at uncorrected p < 0.001 and k = 100 (the most used parameters in the literature). Since PET-analysis rapidly processes different threshold combinations, T-maps were thresholded with multiple p-value and different clusters sizes. The presurgical EZ identified by visual assessment, SPM and PET-analysis was compared to the confirmed EZ according to post-surgical follow-up. Results: PET-analysis obtained 66.7% (20/30) of correctly localizing studies, comparable to the 70.0% (21/30) achieved by visual assessment and significantly higher (p < 0.05) than that obtained with the SPM threshold p < 0.001/k = 100, of 36.7% (11/30). Only one study was positive, albeit non-localizing, with the SPM threshold corrected p < 0.05/k = 50. Concordance was substantial for PET-analysis (κ = 0.643) and visual interpretation (κ = 0.622), being fair for SPM (κ = 0.242). Conclusion: Compared to SPM with the fixed standard parameters, PET-analysis may be superior in EZ localization with its easy and rapid processing of different threshold combinations. The results of this initial proof-of-concept study validate the clinical use of PET-analysis as a robust objective complementary tool to visual assessment for EZ localization.

Comparison of Autonomic Function before and after Surgical Intervention in Patients with Temporal Lobe Epilepsy

Background and Purpose

Refractory temporal lobe epilepsy (TLE) is commonly associated with imbalances in cardiovascular (CV) parasympathetic and sympathetic functions, which are treated using TLE surgery. We investigated the effect of hemispheric lateralization of seizure foci on autonomic CV functions before and after TLE surgery.

Methods

The study was conducted on patients with left TLE (LTLE, n = 23) and right TLE (RTLE, n = 30) undergoing unilateral TLE surgery. To assess the autonomic CV functions, changes in the heart rate (ΔHR) and blood pressure (BP) were measured using a standardized battery of autonomic reactivity tests before surgery and at 3 and 6 months after surgery.

Results

Before surgery, ΔHR and the expiration to inspiration ratio (E:I) during the deep breathing test were higher in the LTLE group than in the RTLE group (both p < 0.001), but both outcomes were comparable between the groups at 3 and 6 months. ΔHR decreased at 3 and 6 months (p < 0.001 and 0.01, respectively) compared with preoperative values. The E:I at 3 months in the LTLE group was lower (p = 0.04) than the preoperative values. Decrease in systolic BP during the head-up tilt test was greater in the LTLE group than in the RTLE group (p = 0.002) before surgery. The maximum increase in diastolic BP during the cold pressor test was lower in the RTLE group at 6 months than that before surgery (p = 0.001) and in the LTLE group (p = 0.002).

Conclusions

We found that hemispheric lateralization of seizure foci in the temporal lobe had a differential effect on autonomic CV functions before surgery. Before surgery, parasympathetic reactivity was higher in the LTLE group, and sympathetic reactivity was higher in the RTLE group. After surgery, autonomic CV functions were comparable between the groups, suggesting that TLE surgery stabilizes autonomic CV functions.

Automated Online Quantification Method for 18F-FDG Positron Emission Tomography/CT Improves Detection of the Epileptogenic Zone in Patients with Pharmacoresistant Epilepsy

Aims

To assess the validity of an online method to quantitatively evaluate cerebral hypometabolism in patients with pharmacoresistant focal epilepsy as a complement to the visual analysis of the ¹⁸F-FDG positron emission tomography (PET)/CT exam.

Methods

A total of 39 patients with pharmacoresistant epilepsy and probable focal cortical dysplasia [22 patients with frontal lobe epilepsy (FLE) and 17 with temporal lobe epilepsy (TLE)] underwent a presurgical evaluation including EEG, video-EEG, MRI, and ¹⁸F-FDG PET/CT. We conducted the automated quantification of their ¹⁸F-FDG PET/CT data and compared the results with those of the visual-PET analysis conducted by experienced nuclear medicine physicians. For each patient group, we calculated Cohen’s Kappa coefficient for the visual and quantitative analyses, as well as each method’s sensitivity, specificity, and positive and negative predictive values.

Results

For the TLE group, both the visual and quantitative analyses showed high agreement. Thus, although the quantitative analysis could be used as a complement, the visual analysis on its own was consistent and precise. For the FLE group, on the other hand, the visual analysis categorized almost half of the cases as normal, revealing very low agreement. For those patients, the quantitative analysis proved critical to identify the focal hypometabolism characteristic of the epileptogenic zone. Our results suggest that the quantitative analysis of ¹⁸F-FDG PET/CT data is critical for patients with extratemporal epilepsies, and especially those with subtle MRI findings. Furthermore, it can easily be used during the routine clinical evaluation of ¹⁸F-FDG PET/CT exams.

Significance

Our results show that quantification of ¹⁸F-FDG PET is an informative complementary method that can be added to the routine visual evaluation of patients with subtle lesions, particularly those in the frontal lobes.

Preoperative evaluation and surgical decision-making in pediatric epilepsy surgery

Epilepsy is a common disease in the pediatric population, and the majority of cases are controlled with medications and lifestyle modification. For the children whose seizures are pharmacoresistant, continued epileptic activity can have a severely detrimental impact on cognitive development. Early referral of children with drug-resistant seizures to a pediatric epilepsy surgery center for evaluation is critical to achieving optimal patient outcomes. There are several components to a thorough presurgical evaluation, including a detailed medical history and physical examination, noninvasive testing including electroencephalogram, magnetic resonance imaging (MRI) of the brain, and often metabolic imaging. When necessary, invasive diagnostic testing using intracranial monitoring can be used. The identification of an epileptic focus may allow resection or disconnection from normal brain structures, with the ultimate goal of complete seizure remission. Additional operative measures can decrease seizure frequency and/or intensity if a clear epileptic focus cannot be identified. In this review, we will discuss the nuances of presurgical evaluation and decision-making in the management of children with drug-resistant epilepsy (DRE).

A screening tool to identify surgical candidates with drug refractory epilepsy in a resource limited settings

OBJECTIVES

Access to epilepsy surgery remains a considerable challenge in contemporary healthcare systems. Given the limitations in resources and demand for Epilepsy Monitoring Unit (EMU) assessments, information that can be used to expedite the process is of great value. The purpose of this study was to identify variables prior to EMU admission that may be associated with candidacy for prospective epilepsy surgery.

METHODS

This was a prospective study conducted at the Department of Neurology, All India Institute of Medical Sciences, New Delhi, India. We identified two subgroups of patients from 501 drug refractory epilepsy (DRE) patients admitted in EMU of Neurology Department, AIIMS from 2006 onwards following validation of proposed tool in 40 patients. They on subsequent investigations were either cleared or not cleared for epilepsy surgery. A tool consisting of variables likely to predict surgical candidacy in persons with DRE in Indian settings was developed for identification of patients who might benefit from an early epilepsy surgery evaluation.

RESULTS

Statistical analysis revealed significant differences between the two groups for several variables. Non-surgical candidates had non-disabling seizures, seizures improved with a combination of drugs, had little/no AEDs side effects and had near normal or normal scalp EEG and MRI brain.

SIGNIFICANCE

Using the best available evidence, we developed a decision making tool which can provide a comprehensive quick guide for determining candidacy for epilepsy surgery evaluations in resource limited settings. Given the demand for EMU assessments, information that can be used to expedite the process is of value.

Neuroimaging in refractory epilepsy. Current practice and evolving trends

Identification of the epileptogenic zone is of paramount importance in refractory epilepsy as the success of surgical treatment depends on complete resection of the epileptogenic zone. Imaging plays an important role in the locating and defining anatomic epileptogenic abnormalities in patients with medically refractory epilepsy. The aim of this article is to present an overview of the current MRI sequences used in epilepsy imaging with special emphasis of lesion seen in our practices. Optimisation of epilepsy imaging protocols are addressed and current trends in functional MRI sequences including MR spectroscopy, diffusion tensor imaging and fusion MR with PET and SPECT are discussed.