Ictal SPECT Research Articles

Epileptic network of hypothalamic hamartoma: An EEG-fMRI study

ObjectiveTo investigate the brain networks involved in epileptogenesis/encephalopathy associated with hypothalamic hamartoma (HH) by EEG with functional MRI (EEG-fMRI), and evaluate its efficacy in locating the HH interface in comparison with subtraction ictal SPECT coregistered to MRI (SISCOM). MethodsEight HH patients underwent EEG-fMRI. All had gelastic seizures (GS) and 7 developed other seizure types. Using a general linear model, spike-related activation/deactivation was analyzed individually by applying a hemodynamic response function before, at, and after spike onset (time-shift model=−8–+4s). Group analysis was also performed. The sensitivity of EEG-fMRI in identifying the HH interface was compared with SISCOM in HH patients having unilateral hypothalamic attachment. ResultsEEG-fMRI revealed activation and/or deactivation in subcortical structures and neocortices in all patients. 6/8 patients showed activation in or around the hypothalamus with the HH interface with time-shift model before spike onset. Group analysis showed common activation in the ipsilateral hypothalamus, brainstem tegmentum, and contralateral cerebellum. Deactivation occurred in the default mode network (DMN) and bilateral hippocampi. Among 5 patients with unilateral hypothalamic attachment, activation in or around the ipsilateral hypothalamus was seen in 3 using EEG-fMRI, whereas hyperperfusion was seen in 1 by SISCOM. SignificanceGroup analysis of this preliminary study may suggest that the commonly activated subcortical network is related to generation of GS and that frequent spikes lead to deactivation of the DMN and hippocampi, and eventually to a form of epileptic encephalopathy. Inter-individual variance in neocortex activation explains various seizure types among patients. EEG-fMRI enhances sensitivity in detecting the HH interface compared with SISCOM.

Ratio Ictal SPECT Co-registered with MRI visualizes a greater extent of the ictal onset zone in focal refractory epilepsy

Background: Until recently, the main non-invasive technique to evaluate the ictal onset zone has been Subtraction ictal SPECT coregistered with MRI (SISCOM). While SISCOM provides useful information about the ictal onset zone, the case we report herein suggests the possibility that multiple regions are involved in a more complex network 7 , whose identification can improve the patient’s prospects for resective epilepsy surgery. Case: The 23 year old right handed female case under discussion illustrates how Ratio Ictal SPECT coregistered with MRI (RISCOM) findings better guided the invasive evaluation with a more precise targeting of the subdural grids. Here, the concordance between the noninvasive technique (RISCOM) and the invasive evaluation (chronic electrocorticography) allowed a better determination of the seizure onset zone for resective epilepsy surgery. In turn, the resected tissue included a more extended area (orbitofrontal), which was not seen by SISCOM. Importantly, the case also allows for a better understanding of the relationship between the epileptogenic lesion and the ictal onset zone, and their role in the postsurgical outcome. The patient achieved seizure freedom (Engel 1A). Conclusion: A more accurate determination of the ictal onset zone by this novel noninvasive technique not only greatly impact in the postsurgical outcome of patients with focal refractory epilepsy. It may also indicate that the ictal onset zone can be the expression of interlobar connections that does not necessarily include the epileptogenic lesion of patients with malformations of cortical development.

Nuclear medicine in pediatric refractory epilepsy

The nuclear medicine procedures 99mTc-ECD SPECT and 18F-FDG PET play an important diagnostic role in children with refractory seizures. In select patients, surgical removal of epileptogenic cortex is a therapeutic option. Magnetic resonance imaging (MRI) is the principal imaging method used to identify which patients would benefit from the surgery. However, there are cases when MRI does not detect an abnormality (MRI-negative epilepsy). Under these, and other circumstances, functional nuclear medicine studies are helpful in the workup of these patients. A combination of nuclear medicine procedures with MRI and CT depicts functional–anatomic relationships and assists in the non-invasive localization of epileptogenic cortex. Information derived from these procedures is valuable in the selection of candidates for surgical resection. Timing of tracer administration in relation to imaging and monitoring the state of brain activation are essential for accurate interpretation. Ictal and interictal perfusion single photon computed tomography (SPECT), with digital subtraction and registration to MRI can define the region of ictal cortical hyperperfusion more clearly than separate image interpretation. Ictal SPECT is more sensitive than interictal positron emission computed tomography (PET) and interictal PET is more sensitive than interictal SPECT. Interictal SPECT and PET are easier to obtain than ictal SPECT, since they do not require coordination between seizure onset and tracer administration. When surface electrode grids or depth electrodes are planned, anatomic-functional images can assist in their anatomic positioning. The best results are obtained when the planning, execution and interpretation of nuclear medicine procedures are carried out with the support of a well-trained multidisciplinary team familiar with children and refractory seizures.

Resecting critical nodes from an epileptogenic circuit in refractory focal-onset epilepsy patients using subtraction ictal SPECT coregistered to MRI.

OBJECTIVE The purpose of this study was to assess the positive predictive value of postresection outcomes obtained by presurgical subtracted ictal SPECT in patients with lesional (MRI positive) and nonlesional (MRI negative) refractory extratemporal lobe epilepsy (ETLE) and temporal lobe epilepsy (TLE). Specifically, outcomes were compared between partial versus complete resection of the regions of transient hyperperfusion identified using subtraction ictal SPECT coregistered to MRI (SISCOM) in relation to the ictal onset zone (IOZ) that was confirmed by electrocorticography (ECoG). That is, SISCOM was used to understand the long-term postsurgical outcomes following resection of the IOZ that overlapped with 1 or more regions of ictal onset-associated transient hyperperfusion. METHODS The study cohort included 44 consecutive patients with refractory ETLE or TLE who were treated between 2002 and 2013 and underwent presurgical evaluation using SISCOM. Concordance was determined between SISCOM localization and the IOZ on the basis of ECoG monitoring. In addition, the association between the extent of the resection site overlapping with the SISCOM signal and postresection outcomes were assessed. Postsurgical follow-up was longer than 24 months in 39 of 44 patients. RESULTS The dominant SISCOM signals were concordant with ECoG and overlapped the resection site in 32 of 44 (73%) patients (19 ETLE and 13 TLE patients), and 20 of 32 (63%) patients became seizure free. In all 19 ETLE patients with concordant SISCOM and ECoG results, the indicated location of ictal onset on ECoG was completely resected; 11 of 19 patients (58%) became seizure free (Engel Class I). In all 13 TLE patients with concordant SISCOM and ECoG results, the indicated ECoG focus was completely resected; 9 of 13 patients (69%) became seizure free (Engel Class I). Complete resection of the SISCOM signal was found in 7 of 34 patients (21%). Of these 7 patients, 5 patients (72%) were seizure free (Engel Class I). Partial resection of the SISCOM signal was found in 16 of 34 patients (47%), and 10 of these 16 patients (63%) were seizure free (Engel Class I) after more than 24 months of follow-up. CONCLUSIONS Concordance between 1 or more SISCOM regions of hyperperfusion with ECoG and at least partial resection of the dominant SISCOM signal in this refractory epilepsy cohort provided additional useful information for predicting long-term postresection outcomes. Such regions are likely critical nodes in more extensive, active, epileptogenic circuits. In addition, SPECT scanner technology may limit the sensitivity of meaningful SISCOM signals for identifying the maximal extent of the localizable epileptogenic network.

The effective connectivity of the seizure onset zone and ictal perfusion changes in amygdala kindled rhesus monkeys.

Epileptic seizures are network-level phenomena. Hence, epilepsy may be regarded as a circuit-level disorder that cannot be understood outside this context. Better insight into the effective connectivity of the seizure onset zone and the manner in which seizure activity spreads could lead to specifically-tailored therapies for epilepsy.We applied the electrical amygdala kindling model in two rhesus monkeys until these animals displayed consistent stage IV seizures. At this stage, we investigated the effective connectivity of the amygdala by means of electrical microstimulation during fMRI (EM-fMRI). In addition, we imaged changes in perfusion during a seizure using ictal SPECT perfusion imaging. The spatial overlap between the connectivity network and the ictal perfusion network was assessed both at the regional level, by calculating Dice coefficients using anatomically defined regions of interest, and at the voxel level.The kindled amygdala was extensively connected to bilateral cortical and subcortical structures, which in many cases were connected multisynaptically to the amygdala. At the regional level, the spatial extents of many of these fMRI activations and deactivations corresponded to the respective increases and decreases in perfusion imaged during a stage IV seizure. At the voxel level, however, some regions showed residual seizure-specific activity (not overlapping with the EM-fMRI activations) or fMRI-specific activation (not overlapping with the ictal SPECT activations), indicating that frequently, only a part of a region anatomically connected to the seizure onset zone participated in seizure propagation.Thus, EM-fMRI in the amygdala of electrically-kindled monkeys reveals widespread areas that are often connected multisynaptically to the seizure focus. Seizure activity appears to spread, to a large extent, via these connected areas.

Towards precision medicine in epilepsy surgery.

Up to a third of all patients with epilepsy are refractory to medical therapy even in the context of the introduction of new antiepileptic drugs (AEDs) with considerable advantages in safety and tolerability over the last two decades. It has been widely accepted that epilepsy surgery is a highly effective therapeutic option in a selected subset of patients with refractory focal seizure. There is no doubt that accurate localization of the epileptogenic zone (EZ) is crucial to the success of resection surgery for intractable epilepsy. The pre-surgical evaluation requires a multimodality approach wherein each modality provides unique and complimentary information. Accurate localization of EZ still remains challenging, especially in patients with normal features on MRI. Whereas substantial progress has been made in the methods of pre-surgical assessment in recent years, which widened the applicability of surgical treatment for children and adults with refractory seizure. Advances in neuroimaging including voxel-based morphometric MRI analysis, multimodality techniques and computer-aided subtraction ictal SPECT co-registered to MRI have improved our ability to identify subtle structural and metabolic lesions causing focal seizure. Considerable observations from animal model with epilepsy and pre-surgical patients have consistently found a strong correlation between high frequency oscillations (HFOs) and epileptogenic brain tissue that suggest HFOs could be a potential biomarker of EZ. Since SEEG emphasizes the importance to study the spatiotemporal dynamics of seizure discharges, accounting for the dynamic, multidirectional spatiotemporal organization of the ictal discharges, it has greatly deep our understanding of the anatomo-electro-clinical profile of seizure. In this review, we focus on some state-of-the-art pre-surgical investigations that contribute to the precision medicine. Furthermore, advances also provide opportunity to achieve the minimal side effects and maximal benefit individually, which meets the need for the current concept of precision medicine in epilepsy surgery.

Ictal SPECT in patients with REM sleep behavior disorder

Ictal SPECT in patients with REM sleep behavior disorder

Perfusion SPECT, SISCOM and PET (18)F-FDG in the assessment of drug- refractory epilepsy patients candidates for epilepsy surgery.

Brain perfusion SPECT (ictal-interictal), SPECT images and subtraction ictal SPECT coregistered to MRI (SISCOM) and (18)F-FDG-PET (interictal), play an important role in the pre-surgical diagnosis of patients with medically refractory epilepsy. This study aimed to establish: the reproducibility of visual ictal-interictal SPECT and SISCOM analysis altogether with the capacity of SPECT, SISCOM and PET to determine the epileptogenic zone. (99m)Tc-HMPAO SPECT ictal-interictal and SISCOM (Analyze 7.0) were performed on 47 refractory epilepsy patients (24 F, 19-60 yrs). In 13 patients, SISCOM was also performed using a new program (Focus DET). Ictal-interictal SPECT and SISCOM images were analysed independently by two nuclear medicine physicians (observer 1 and 2). Kappa concordance coefficient was used to evaluate the reproducibility. In sixteen patients, SPECT, SISCOM and PET findings were compared with the resected area during the surgery, and surgical outcome using Engel scale or with the stereo EEG-(SEEG). The ictal-interictal SPECT interobserver agreement was 91%, Kappa index 0.86, SISCOM (Analyze 7.0) interobserver agreement percentage was 82%, Kappa index 0.80, Analyze 7.0 showed a higher inconclusive results than visual SPECT analysis. SISCOM FocusDET interobserver agreement was 92%, Kappa index 0.87, with lower inconclusive results than Analyze 7.0. SPECT, SISCOM and PET combined findings identified 87% seizure onset zone: 79% temporal, 26% parieto-temporal and 7% frontal. Ictal-interictal SPECT and SISCOM showed a high reproducibility in this sample of patients with drug-refractory epilepsy. SPECT,SISCOM and PET combined findings improved detection of epileptogenic zone in comparison with the individual assessment.

Perfusion SPECT, SISCOM and PET 18F-FDG in the assessment of drug-refractory epilepsy patients candidates for epilepsy surgery

AimsBrain perfusion SPECT (ictal–interictal), SPECT images and subtraction ictal SPECT coregistered to MRI (SISCOM) and 18F-FDG-PET (interictal) play an important role in the pre-surgical diagnosis of patients with medically refractory epilepsy.This study aimed to establish the reproducibility of visual ictal–interictal SPECT and SISCOM analysis altogether with the capacity of SPECT, SISCOM and PET to determine the epileptogenic zone. Material and methods99mTc-HMPAO SPECT ictal–interictal and SISCOM (Analyze 7.0) were performed on 47 refractory epilepsy patients (24 F, 19–60 yrs). In 13 patients, SISCOM was also performed using a new programme (Focus DET). Ictal–interictal SPECT and SISCOM images were analyzed independently by two nuclear medicine physicians (observers 1 and 2). Kappa concordance coefficient was used to evaluate the reproducibility. In sixteen patients, SPECT, SISCOM and PET findings were compared with the resected area during the surgery, and surgical outcome using Engel scale or with the stereo EEG-(SEEG). ResultsThe ictal–interictal SPECT interobserver agreement was 91%, Kappa index 0.86, SISCOM (Analyze 7.0) interobserver agreement percentage was 82%, Kappa index 0.80, Analyze 7.0 showed a higher inconclusive results than visual SPECT analysis. SISCOM FocusDET interobserver agreement was 92%, Kappa index 0.87, with lower inconclusive results than Analyze 7.0. SPECT, SISCOM and PET combined findings identified 87% seizure onset zone: 79% temporal, 26% parieto-temporal and 7% frontal. ConclusionsIctal–interictal SPECT and SISCOM showed a high reproducibility in this sample of patients with drug-refractory epilepsy. SPECT, SISCOM and PET combined findings improved detection of epileptogenic zone in comparison with the individual assessment.

Focal epilepsies refractory to AEDs: Algorithms to identify treatable causes

Epilepsy can be due to CNS diseases or lesions, or systemic disorders. Patients with presumed focal epilepsy refractory to antiepileptic drugs need comprehensive revaluation. It is important to establish a patient is truly drug refractory. Current guidelines suggest that using two AEDs either sequentially or, preferably, in combination can establish drug failure, as long as drugs are given in adequate doses for enough time. Video-EEG recording can confirm a patient has focal rather than primary generalized epilepsy, and support focus localization. Family members may give clues to etiology such as a history of complex or prolonged febrile seizures, implying potential mesial temporal sclerosis. Family history may suggest heritable syndromes, such as Autosomal Dominant Partial Epilepsy with Auditory Features. History and physical examination may lead to appropriate studies to detect a systemic disorder. Limbic encephalitis is now recognized as a cause of refractory epilepsy, particularly if patients have subacute onset, and cognitive or psychiatric symptoms. MRI is increasingly sensitive for detecting drug-refractory focal epilepsy structural etiologies. MRI techniques such as magnetization transfer as well as novel approaches to post-processing may detect lesions such as focal cortical dysplasia not seen on standard scans. FDG-PET can detect focal hypometabolism, and subtraction ictal SPECT increased blood flow, in some patients with normal MRI, suggesting reasonable focal resection prognosis, or guiding intracranial EEG studies. Their value when MRI shows a lesion is less clear. Other PET ligands can image neurotransmitter receptor binding, serotonin precursor uptake or neuroinflammation with valuable research results but limited clinical application.

P93. Ictal SPECT in patients with REM sleep behavior disorder

Introduction Patients with idiopathic REM sleep behavior disorder (iRBD) have the same phenotype as those with Parkinson and RBD (PD + RBD) and narcolepsy and RBD (nRBD). Little is known if different types of RBD share the same pathways during their nocturnal activities. The aim of the study was to compare ictal SPECT of different types of RBD. Methods Recording was performed as 22 channel video-EEG polysomnography using an IT- Med system l. Ictal and interictal subtraction SPECT was performed after using a semiautomatic SPECT injection device permitting immediate intravenous application of the radioligand ECD with a latency or 10 epochs and complex behavior in REM sleep > 10 epochs. Ictal and interictal reconstructed datasets were subtracted pixelwise from each other, the difference images were coregistered to MRI images. Patients 2 iRBD, 2 with nRBD. 1 iRBD patient had converted to Parkinson’s disease (Hoehn & Yahr 4). Patients fulfilled RBD criteria according to the International Classification of Sleep Disorders 2 (2005). All patients gave their written consent. The study was approved by the Ethical Committee of the Chamber of Physicians of the state of Hessen/Germany. Results All patients independent of their RBD type displayed a similar pattern of activation in the ictal SPECT. The activation included the premotor areas bilaterally, the interhemispheric cleft, the periaqueductal area, the dorsal and ventral pons and the anterior part of the cerebellum. Conclusion The ictal pathway of RBD is the same in iRBD, PD + RBD and nRBD.

REM sleep behaviour disorder: a window on the sleeping brain.

This scientific commentary refers to ‘Ictal SPECT in patients with rapid eye movement sleep behaviour disorder’, by Mayer et al. (doi:10.1093/brain/awv042). REM sleep behaviour disorder (RBD) continues to serve as an increasingly instructive window on the sleeping brain. The identification of RBD in humans in 1986 was predicted by Michel Jouvet’s 1965 feline model produced by bilateral perilocus coeruleus lesions and subsequently replicated in the rat (Schenck et al. , 2002). Initially, human RBD was felt to be a curious and fascinating experiment in nature resulting in the isolated absence of atonia during REM sleep, permitting the ‘acting out of dreams’ (or, the ‘dreaming out of acts’). As more diverse groups of patients were studied, and as patients with RBD were followed over time, a number of interesting facts and correlations emerged. One of these was that the overwhelming majority (up to 90%) of patients with what initially appeared to be ‘idiopathic’ RBD would eventually develop a neurodegenerative disease (often following a delay of decades), particularly one of the synucleinopathies (Parkinson’s disease, dementia with Lewy bodies, or multiple system atrophy) (Iranzo et al. , 2014). Furthermore, waking motor manifestations of bradykinesia and hypophonia in patients with comorbid Parkinson’s disease and RBD were markedly improved during movements and vocalizations within episodes of RBD (De Cock et al. , 2007). Similar findings were reported for RBD associated with multiple system atrophy (De Cock et al. , 2011), with enhanced facial expression, improved speech and faster/stronger movements in REM sleep compared to wakefulness. These improvements were unlikely to be due to enhanced dopamine transmission because patients with multiple system atrophy are poorly …

Ictal SPECT in patients with rapid eye movement sleep behaviour disorder.

Rapid eye movement sleep behaviour disorder is a rapid eye movement parasomnia clinically characterized by acting out dreams due to disinhibition of muscle tone in rapid eye movement sleep. Up to 80-90% of the patients with rapid eye movement sleep behaviour disorder develop neurodegenerative disorders within 10-15 years after symptom onset. The disorder is reported in 45-60% of all narcoleptic patients. Whether rapid eye movement sleep behaviour disorder is also a predictor for neurodegeneration in narcolepsy is not known. Although the pathophysiology causing the disinhibition of muscle tone in rapid eye movement sleep behaviour disorder has been studied extensively in animals, little is known about the mechanisms in humans. Most of the human data are from imaging or post-mortem studies. Recent studies show altered functional connectivity between substantia nigra and striatum in patients with rapid eye movement sleep behaviour disorder. We were interested to study which regions are activated in rapid eye movement sleep behaviour disorder during actual episodes by performing ictal single photon emission tomography. We studied one patient with idiopathic rapid eye movement sleep behaviour disorder, one with Parkinson's disease and rapid eye movement sleep behaviour disorder, and two patients with narcolepsy and rapid eye movement sleep behaviour disorder. All patients underwent extended video polysomnography. The tracer was injected after at least 10 s of consecutive rapid eye movement sleep and 10 s of disinhibited muscle tone accompanied by movements registered by an experienced sleep technician. Ictal single photon emission tomography displayed the same activation in the bilateral premotor areas, the interhemispheric cleft, the periaqueductal area, the dorsal and ventral pons and the anterior lobe of the cerebellum in all patients. Our study shows that in patients with Parkinson's disease and rapid eye movement sleep behaviour disorder-in contrast to wakefulness-the neural activity generating movement during episodes of rapid eye movement sleep behaviour disorder bypasses the basal ganglia, a mechanism that is shared by patients with idiopathic rapid eye movement sleep behaviour disorder and narcolepsy patients with rapid eye movement sleep behaviour disorder.

The stereotactic approach for mapping epileptic networks: a prospective study of 200 patients.

Stereoelectroencephalography (SEEG) is a methodology that permits accurate 3D in vivo electroclinical recordings of epileptiform activity. Among other general indications for invasive intracranial electroencephalography (EEG) monitoring, its advantages include access to deep cortical structures, its ability to localize the epileptogenic zone when subdural grids have failed to do so, and its utility in the context of possible multifocal seizure onsets with the need for bihemispheric explorations. In this context, the authors present a brief historical overview of the technique and report on their experience with 2 SEEG techniques (conventional Leksell frame-based stereotaxy and frameless stereotaxy under robotic guidance) for the purpose of invasively monitoring difficult-to-localize refractory focal epilepsy. Over a period of 4 years, the authors prospectively identified 200 patients with refractory epilepsy who collectively underwent 2663 tailored SEEG electrode implantations for invasive intracranial EEG monitoring and extraoperative mapping. The first 122 patients underwent conventional Leksell frame-based SEEG electrode placement; the remaining 78 patients underwent frameless stereotaxy under robotic guidance, following acquisition of a stereotactic ROSA robotic device at the authors' institution. Electrodes were placed according to a preimplantation hypothesis of the presumed epileptogenic zone, based on a standardized preoperative workup including video-EEG monitoring, MRI, PET, ictal SPECT, and neuropsychological assessment. Demographic features, seizure semiology, number and location of implanted SEEG electrodes, and location of the epileptogenic zone were recorded and analyzed for all patients. For patients undergoing subsequent craniotomy for resection, the type of resection and procedure-related complications were prospectively recorded. These results were analyzed and correlated with pathological diagnosis and postoperative seizure outcomes. The epileptogenic zone was confirmed by SEEG in 154 patients (77%), of which 134 (87%) underwent subsequent craniotomy for epileptogenic zone resection. Within this cohort, 90 patients had a minimum follow-up of at least 12 months; therein, 61 patients (67.8%) remained seizure free, with an average follow-up period of 2.4 years. The most common pathological diagnosis was focal cortical dysplasia Type I (55 patients, 61.1%). Per electrode, the surgical complications included wound infection (0.08%), hemorrhagic complications (0.08%), and a transient neurological deficit (0.04%) in a total of 5 patients (2.5%). One patient (0.5%) ultimately died due to intracerebral hematoma directly ensuing from SEEG electrode placement. Based on these results, SEEG methodology is safe, reliable, and effective. It is associated with minimal morbidity and mortality, and serves as a practical, minimally invasive approach to extraoperative localization of the epileptogenic zone in patients with refractory epilepsy.

BRIEF REPORT ON REFLEX EPILEPSY

Reflex epilepsies are a rare, unusual, complex & bizarre group of epilepsies seen most commonly in adolescent females ,most probably due to the hyper synchronization & propagation of epileptic cortex which are connected to each other through functional network occurring in innocuous ways such as an olfactory stimuli or as common as a sensory, visual, somato-sensory or a proprioceptive stimuli either isolated or in combination. However, there could be other set of unusual, however more complex & well known precipitants such as praxis, listening to music or reading a book. These can be diagnosed through a combination of good clinical history, Video EEG monitoring & Imaging of the brain especially functional MRI, ictal SPECT. Avoiding exposure to inciting stimulus and adequate anti-epileptic medication, forms the corner stone of treatment of this condition.

Clinical Role of Subtraction Ictal SPECT Coregistered to MR Imaging and18F-FDG PET in Pediatric Epilepsy

A precise assessment of the drug-resistant epileptic pediatric population for surgical candidacy is often challenging, and to date there are no evidence-based guidelines for presurgical identification of the epileptogenic zone. To evaluate the usefulness of radionuclide imaging techniques for presurgical evaluation of epileptic pediatric patients, we compared the results of video-electroencephalography (EEG), brain MR imaging, interictal SPECT, ictal SPECT, subtraction ictal SPECT coregistered to MR imaging (SISCOM), and interictal PET with (18)F-FDG. Fifty-four children with drug-resistant epilepsy who had undergone video-EEG monitoring, brain MR imaging, interictal and ictal brain perfusion SPECT, SISCOM, and (18)F-FDG PET were included in this study. All abnormal findings revealed by these neuroimaging techniques were compared with the presumed location of the epileptogenic zone (PEZ) as determined by video-EEG and clinical data. The proportion of localizing studies for each technique was statistically compared. In the 18 patients who underwent resective brain surgery, neuroimaging results were compared with histopathology results and surgical outcome. SISCOM and (18)F-FDG PET concordance with the PEZ was significantly higher than MR imaging (P < 0.05). MR imaging showed localizing results in 21 of 54 cases (39%), SISCOM in 36 of 54 cases (67%), and (18)F-FDG PET in 31 of 54 cases (57%). If we consider SISCOM and (18)F-FDG PET results together, nuclear medicine imaging techniques showed coinciding video-EEG results in 76% of patients (41/54). In those cases in which MR imaging failed to identify any epileptogenic lesion (61% [33/54]), SISCOM or (18)F-FDG PET findings matched PEZ in 67% (22/33) of cases. SISCOM and (18)F-FDG PET provide complementary presurgical information that matched video-EEG results and clinical data in three fourths of our sample. SISCOM was particularly useful in those cases in which MR imaging findings were abnormal but no epileptogenic lesion was identified. Radionuclide imaging techniques are both useful and reliable, extending the possibility of surgical treatment to patients who may have been discouraged without a nuclear medicine approach.

PET and SPECT in epilepsy

Epilepsy is one of the most frequent chronic neurological disorders, affecting 1–2% of the population. Patients with complex partial drug resistant episodes may benefit from a surgical treatment consisting in the excision of the epileptogenic area. Localization of the epileptogenic area was classically performed with video-EEG and magnetic resonance (MR). Recently, functional neuroimaging studies of nuclear medicine, positron emission tomography (PET) and single photon emission tomography (SPECT) have demonstrated their utility in the localization of the epileptogenic area prior to surgery. Ictal SPECT with brain perfusion tracers show an increase in blood flow in the initial ictal focus, while PET with 18FDG demonstrates a decrease of glucose metabolism in the interictal functional deficit zone.In this review, the basic principles and methodological characteristics of the SPECT and PET in epilepsy are described. The ictal SPECT injection mechanism, different patterns of perfusion based on the time of ictal, postictal or interictal injection are detailed and the different diagnostic sensitivities of each one of these SPECT are reviewed. Different methods of analysis of the images by subtraction and fusion systems with the MR are described. Similarly, the injection methodology, quantification and evaluation of the images of the PET in epilepsy are described. Finally, the main clinical indications of SPECT and PET in temporal and extratemporal epilepsy are detailed.

Concomitant use of stereoelectroencephalography (SEEG) and magnetoencephalographic (MEG) in the surgical treatment of refractory focal epilepsy

In patients with refractory focal epilepsy, the success in localzing and completely resecting the epileptic focus has been shown o be the most important predictor of seizure freedom in patients houndergo surgical resections [1]. In order to achieve these goals, arious non-invasive conventional tools are available, including nalysis of seizure semiology, prolonged video-scalp electroenephalographic (video-EEG) recordings, ictal SPECT and PET scans. hen no non-invasive data congruency is achieved, additional ocalizing methods may be required. At our institution and others, tereoelectroencephalography (SEEG) and magenetoencephalogaphy (MEG) have increasingly been used as complimentary ocalizing tools to assist with the localization of the EZ in patients ith “difficult to localize” medically refractory focal epilepsy [2,3]. The authors report a case of a 29-year-old male with nonesional epilepsywho underwentmultiple non-invasive studies for reoperative work-up of epilepsy. After multidisciplinary Epilepsy anagement Conference, the decision was made to perform SEEG mplantation for the localization of the EZ. A MEG study was erformed with SEEG electrodes in place and both studies localzed the EZ to a small area in the right peri-rolandic opercular egion. Currently, there are no reports describing the utility of

Subtraction Imaging and MR Co-Registration To Increase Diagnostic Yield Of Ictal And Interictal SPECT In Localization Of Epileptogenic Foci In Patients With Intractable Seizures (P6.191)

Subtraction Imaging and MR Co-Registration To Increase Diagnostic Yield Of Ictal And Interictal SPECT In Localization Of Epileptogenic Foci In Patients With Intractable Seizures (P6.191)

Resective surgery in the treatment of super-refractory partial status epilepticus secondary to NMDAR antibody encephalitis

BackgroundAnti-NMDAR encephalitis is an increasingly described clinical entity in children, comprising 40% of all cases. We present a case of super-refractory status epilepticus secondary to anti-NMDAR encephalitis treated with emergent resective surgery. Case studyA 7 years-old boy presented with progressive abnormal irritability. On the day after admission he had multiple seizures, characterized by head and eye version to the right. EEG revealed left parietal-occipital continuous paroxysmal activity. Anti-NMDAR antibodies were positive in CSF and serum. After almost 3 months in the Intensive Care Unit, in barbituric coma, and given the failure of all treatment regimens, a preoperative evaluation was conducted. Ictal SPECT showed significant hiperperfusion and brain FDG-PET a cortical hypometabolism in the left occipital lobe; a left occipital lobectomy was performed. In the next days it was possible to progressively suspend Thiopental. Currently, patient presents right homonymous hemianopsia, eats by his own hand but needs help in almost all other activities. DiscussionStatus epilepticus (SE) in the setting of anti-NMDAR encephalitis is unusual but described. Whilst the role of surgery in the management of refractory focal epilepsy is established, it is seldom used in the treatment of SE. In the patient with refractory SE (RSE), awareness of surgery as a potentially life saving treatment is an important issue. To our knowledge, this is the first report of a partial RSE secondary to anti-NMDAR encephalitis treated with resective surgery and illustrates the need to consider anti-NMDAR encephalitis as a cause of super-refractory SE.