Resection Of Zone Research Articles

Indocyanine green in deep infiltrating endometriosis: a preliminary feasibility study to examine vascularization after rectal shaving

To evaluate the feasibility of using indocyanine green (ICG) to estimate the vascularization of the resected zone during a laparoscopic rectal shaving. Indocyanine green can highlight blood vascularization when injected intravenously. There is no relevant, objective, intraoperative method to assess the vascularity of the resected zone during a laparoscopic rectal shaving for deep infiltrating endometriosis (DIE) to prevent fistula. We conducted a registered clinical trial examining the feasibility of the use of ICG to evaluate the bowel vascularization after endometriosis rectal shaving (Institutional Review Board number 2016-002773-35). Tertiary university hospital. Twenty-one patients underwent laparoscopic surgery for DIE with a rectal shaving. Patients undergoing laparoscopic surgery for DIE received ICG intravenously at the end of the endometriosis resection. The main evaluation criteria was the fluorescence degree in the operated rectal area and in the vaginal suture. We used a visual assessment with a Likert-type scale from 0 to 4 (0 = no fluorescence; 4 = very good fluorescence). No adverse reaction was recorded. Most of the patients (81%) showed very good fluorescence levels at the rectal shaving area. The protocol did not increase the operating time. In one patient we changed the surgical strategy making two stitches to bring the rectal muscularis closer together, which improved the degree of fluorescence. There was no case of digestive fistula. Indocyanine green fluorescent imaging is feasible in endometriosis surgery and may be considered as a potential candidate to further enhance patient safety in endometriosis bowel surgery. NCT03080558.

Using intracorporeal hypothermic perfusion in removal of single kidney tumor with spread to the main renal vein

The paper presents the experience of using hypothermic cold perfusion of a kidney in situ when performing complex nephron-sparing surgery for a tumor of a single right kidney with spreading to the main renal vein. The technique of the operation included separate clamping on the renal artery and IVC in the area of the cavorenal segment. Then the renal artery was opened and cannulated, and a vena cava was opened as a longitudinal section. The kidney was washed with a solution of kustadiol cooled to 4 °C. Then we performed standard steps of kidney resection, removal of the arterial cannula and suturing of the renal artery and inferior vena cava (IVC) sections. The patient underwent extrarenal thrombectomy with reconstruction of the renal vein using a flap v. saphena magna. The time of cold ischemia was 76 minutes. The main advantages of this approach are good visibility of the resection zone, bloodless surgical field and the possibility of long-term safe renal ischemia. To assess the effectiveness of perfusion hypothermic kidney protection in situ, further accumulation of experience in conducting these operations is required.

Cortical high-frequency oscillation loops initiate spasm seizures

Some epileptic spasms are classified into focal-onset seizures. However, the cortical network underlying this kind of spasm seizure is not yet clear. Four patients with epileptic spasms who underwent intracranial electrode implantation and focal resection surgery were studied. All the patients had good outcomes, and three of them with intellectual disability showed improved intelligence after surgery. The power spectra characteristics of electrocorticography and the dynamic functional network changes of epileptic spasms were investigated. Electrocorticography power in the resected zone peaked 0.5 seconds before the clinical seizure onset and was especially prominent in the γ and ripple bands. The functional network analysis showed particular dynamic patterns of high-frequency activity among the resected zone, sensorimotor cortex, and the other region. In the gamma band, during the interictal segment, the information flow from the resected zone and the other region to the sensorimotor cortex was prominent. During the preictal segment, the information flow from the resected zone and sensorimotor cortex to the other region became stronger. In the ripple band, during the interictal segment, the information flow from the resected zone to the sensorimotor cortex and the other region was high. During the preictal segment, the information flow between the resected zone and sensorimotor cortex became stronger. Our results suggest that the sensorimotor cortex is a requisite for spasm seizure initiation, and the ripple activity loop between the resected zone and sensorimotor cortex may give rise to the seizure onset with the help of the gamma activity loop between the sensorimotor cortex and the other region for activation spreading.

Ictal EEG source imaging and connectivity to localize the seizure onset zone in extratemporal lobe epilepsy

PurposeTo evaluate the yield of Functional Connectivity (FC) in addition to low-density ictal Electrical Source Imaging (ESI) in extratemporal lobe epilepsy (ETLE), using an automated algorithm for analysis. MethodLong-term EEG monitoring of consecutive ETLE patients who underwent surgery was reviewed by epileptologists, and seizure onsets characterized by rhythmical activity were identified. A spectrogram-based algorithm was developed to select objectively the parameters of ESI analysis. Two methods for SOZ localization were compared: i) ESI power, based on LORETA exclusively; ii) ESI + FC, including a Granger causality-based connectivity analysis. Results were determined at a sublobar level. The resection zone, in relation to 1-year follow-up surgical outcome, was considered as reference standard for diagnostic accuracy analyses. ResultsNinety-four seizures from 24 patients were analyzed. At seizure-level, ESI power showed 36 % sensitivity and 72 % specificity (accuracy: 45 %). ESI + FC significantly improved the accuracy, with 52 % sensitivity and 84 % specificity (accuracy: 61 %, p = 0.04). Results of ESI + FC were equally valuable in patients with lateralized or bilateral/generalized visual interpretation of ictal EEG. In a patient level sub-analysis, upon blinded clinical interpretation, ESI + FC showed a correct localization in 67 % of patients and substantial inter-rater agreement (kappa = 0.64), against 27 % achieved by ESI power, with fair inter-rater agreement (kappa = 0.37). ConclusionFC significantly improves SOZ localization compared to ESI solely in ETLE. Ictal ESI + FC could represent a novel option in the armamentarium of presurgical evaluation, aiding also in patients with visually non-localizable scalp ictal EEG. Prospective studies evaluating the clinical added value of automated low-density ictal ESI may be justified.

Lesion-Constrained Electrical Source Imaging: A Novel Approach in Epilepsy Surgery for Tuberous Sclerosis Complex.

Electrical source imaging may yield ambiguous results in multilesional epilepsy. The aim of this study was to test the clinical utility of lesion-constrained electrical source imaging in epilepsy surgery in children with tuberous sclerosis complex. Lesion-constrained electrical source imaging is a novel method based on a proposed head model in which the source solution is constrained to lesions. Using a goodness of fit analysis, we rank-ordered individual tubers by their ability to approximate interictal and ictal EEG data. The overlap with the surgical resection cavity was determined qualitatively, and placed findings in the context of epilepsy surgical outcome, and compared with the low-resolution brain electromagnetic tomography solution. Low-resolution brain electromagnetic tomography predicted the surgical cavity in only one patient with good outcome (true positive) and localized to outside of the cavity in two patients with a good outcome (false negative). In one patient with a poor outcome, the interictal low-resolution brain electromagnetic tomography solution overlapped with the cavity (false positive). Lesion-constrained electrical source imaging of ictal EEG data identified tubers concordant with the resection zone in three patients with a good surgical outcome (true positive) and appropriately discordant in three other patients with a poor outcome (true negative). Lesion-constrained electrical source imaging on low-resolution EEG data provides complementary information in the presurgical workup for patients with tuberous sclerosis complex, although further validation is required. In the appropriate clinical context, the yield of source localization on low-resolution EEG data may be increased by reduction of the solution space.

Virtual resection predicts surgical outcome for drug-resistant epilepsy.

Patients with drug-resistant epilepsy often require surgery to become seizure-free. While laser ablation and implantable stimulation devices have lowered the morbidity of these procedures, seizure-free rates have not dramatically improved, particularly for patients without focal lesions. This is in part because it is often unclear where to intervene in these cases. To address this clinical need, several research groups have published methods to map epileptic networks but applying them to improve patient care remains a challenge. In this study we advance clinical translation of these methods by: (i) presenting and sharing a robust pipeline to rigorously quantify the boundaries of the resection zone and determining which intracranial EEG electrodes lie within it; (ii) validating a brain network model on a retrospective cohort of 28 patients with drug-resistant epilepsy implanted with intracranial electrodes prior to surgical resection; and (iii) sharing all neuroimaging, annotated electrophysiology, and clinical metadata to facilitate future collaboration. Our network methods accurately forecast whether patients are likely to benefit from surgical intervention based on synchronizability of intracranial EEG (area under the receiver operating characteristic curve of 0.89) and provide novel information that traditional electrographic features do not. We further report that removing synchronizing brain regions is associated with improved clinical outcome, and postulate that sparing desynchronizing regions may further be beneficial. Our findings suggest that data-driven network-based methods can identify patients likely to benefit from resective or ablative therapy, and perhaps prevent invasive interventions in those unlikely to do so.

Confocal-Assisted Fluorescence Resection of Low-Grade Gliomas

Abstract INTRODUCTION Low-grade gliomas (LGG) are the most common intra-axial brain tumors. Intraoperatively it's not possible to distinguish optically between the tumor and the normal tissue. Furthermore, it can not be detected with fluorescent agents like 5-aminolevulinacid (5-ALA). Those reasons often lead to inaccurate resection of the tumor. Confocal laser endomicroscopy (CLE) is a cellular imaging modality used for optical biopsies. The aim of this study was to use intraoperative CLE to differentiate tumor from normal tissue and to define borders during resection of LGG on a cellular level. METHODS We investigated the use of intraoperative CLE on 6 patients with LGG. We used a confocal system that is able to detect fluorescence on the infrared spectrum and we applied indocyanine green as a detecting fluorescent agent. We analyzed the accuracy of the intraoperative cellular CLE optical biopsies in comparison with the hematoxylin and eosin stains of the biopsies taken from the tumor and normal tissue borders area. RESULTS With CLE we were able intraoperatively to diagnose the tumor entity, normal brain structures, and vascularization modalities and to control the resection zone on a cellular level. Furthermore, CLE pictures showed exactly the cellular borders between tumor and normal tissue. The correlation of the CLE pictures with the H&E staining was 100%. CONCLUSION CLE, on one hand, allows intraoperative detection and differentiation of single tumor cells, while, on the other hand, it allows defining borders between tumor and normal tissue on a cellular level, dramatically improving the accuracy of surgical resection of LGG. The application and implementation of CLE-assisted surgery increases not only the options for real-tumor identification but also the therapeutic options by extending the resection borders of LGG on a cellular level and, more importantly, by protecting the functionality of normal tissue on the adjacent areas of the human brain.

Vascular involvement in anterior clinoidal meningiomas : Biting the ‘artery’ that feeds

ObjectivesAnterior clinoidal (AC) meningiomas often encase internal carotid artery (ICA) and it branches. The aim of this study was to determine the efficacy of preoperative angiogram as a predictor of vessel wall adherence and feeders. Furthermore, defining the dangerous areas would provide insights to decrease vascular injury and achieve maximal safe resection. Patients and methods21 cases of AC Meningiomas were evaluated for feeders, displacement, encasement/ narrowing of ICA and its branches. Intraoperative vascular involvement was noted. The reason and site of vascular injury, if any was evaluated. ResultsBlush from ICA was seen in 15 patients. The ICA in its entirety beyond the bifurcation was encased in 11 patients. The radiological vascular encasement including narrowing didn’t corroborate with intra-operative finding of vessel wall adherence. The tumor could be separated along the length of encased narrowed vessel except from ICA bifurcation in 6, where it had infiltrated adventitial layer. The adherent zone extended into anterior cerebral artery in 2 and middle cerebral artery in 2. There was major vessel injury in 2 patients and perforator injury in 2. GTR was achieved in 18 patients. ConclusionThese tumours are often fed by supraclinoid ICA. It is possible to resect the tumor from vessel wall despite complete encasement/ narrowing on preoperative angiograms. The tumor often lethally embraces the ICA bifurcation making it the most dangerous zone for resection. This is possibly due to an arterial twig that arises close to the bifurcation to irrigate the clinoidal dura and the tumor infiltrates the adventitia at its origin.

P20-T Networks associated with clinical responses evoked by high-frequency intracranial stimulation

Pre surgical evaluation in drug resistant epilepsy is based also on invasive EEG recordings in order to accurately establish the epileptogenic zone for surgical resection as well as the eloquent cortex that should be spared. During intracranial session we record ictal events and we apply different stimulation protocols to study functional cortex. In our centre we use the stereo-EEG method to identify the epileptogenic networks and mainly high frequency (50 Hz) stimulation for cortical mapping. By modulating the properties of the stimulation waveforms, in conjunction with the nonlinear response of the tissue to electrical stimulation, we were able to recover the physiological responses during the course of the stimulation train. The activation of the networks at stimulation levels evoking a clinical symptom was compared with the below-threshold stimulation, that did not elicit any clinical effects, allowing to evidence a selective recruitment of pathways associated with a particular symptom. The method is used for identification of physiologic networks associated with various somatosensory, motor or language-related symptoms, to investigate the impact of epileptogenic zone to functional cortex as well as to predict a possible post surgical deficit.

High interictal connectivity within the resection zone is associated with favorable post-surgical outcomes in focal epilepsy patients.

Patients with drug-resistant focal epilepsy are often candidates for invasive surgical therapies. In these patients, it is necessary to accurately localize seizure generators to ensure seizure freedom following intervention. While intracranial electroencephalography (iEEG) is the gold standard for mapping networks for surgery, this approach requires inducing and recording seizures, which may cause patient morbidity. The goal of this study is to evaluate the utility of mapping interictal (non-seizure) iEEG networks to identify targets for surgical treatment. We analyze interictal iEEG recordings and neuroimaging from 27 focal epilepsy patients treated via surgical resection. We generate interictal functional networks by calculating pairwise correlation of iEEG signals across different frequency bands. Using image coregistration and segmentation, we identify electrodes falling within surgically resected tissue (i.e. the resection zone), and compute node-level and edge-level synchrony in relation to the resection zone. We further associate these metrics with post-surgical outcomes. Greater overlap between resected electrodes and highly synchronous electrodes is associated with favorable post-surgical outcomes. Additionally, good-outcome patients have significantly higher connectivity localized within the resection zone compared to those with poorer postoperative seizure control. This finding persists following normalization by a spatially-constrained null model. This study suggests that spatially-informed interictal network synchrony measures can distinguish between good and poor post-surgical outcomes. By capturing clinically-relevant information during interictal periods, our method may ultimately reduce the need for prolonged invasive implants and provide insights into the pathophysiology of an epileptic brain. We discuss next steps for translating these findings into a prospectively useful clinical tool.

Вплив монополярного та біполярного методів резекції на відновні процеси в підшлунковій залозі

Мета. Порівняти особливості зміни тканин підшлункової залози після експериментальних хірургічних втручань, виконаних з використанням стандартної хірургічної техніки та біполярного і монополярного зварювання.
 Матеріали і методи. В умовах експерименту виконували резекцію підшлункової залози у білих лабораторних щурів з використанням стандартної хірургічної техніки, високоенергетичного електрохірургічного інструмента в біполярному режимі, високоенергетичного електрохірургічного інструмента в монополярному режимі. Гістологічні дослідження залози проводили безпосередньо після виконання операції та через 3, 7, 21 добу із застосуванням світлооптичного мікроскопа Leica DМ500.
 Результати. Після застосування стандартної хірургічної техніки в ранні терміни виникало більш виражене запалення та швидше наростав об’єм новоутвореної сполучної тканини, ніж після використання електрохірургічних методів у біполярному та монополярному режимах. Після обох видів електрорезекції в новоутвореній тканині на 7-му добу формувались протоки, чого не спостерігали після використання стандартної техніки. Після резекції, виконаної за допомогою монополярного зварювання, утворювався менш щільний коагуляційний прошарок, ніж після застосування біполярного методу. Через 21 добу в зоні резекції формувався більш значний об’єм сполучної тканини та зберігалися більш виражені ознаки запалення, ніж після використання біполярного методу.
 Висновки. У разі використання біполярної та монополярної техніки резекції скорочується тривалість виконання оперативного втручання, зменшується ризик виникнення кровотечі, утворюється більш герметичне з’єднання на резектованій поверхні, не ускладнюються процеси відновлення.

Експериментальне дослідження морфологічних змін у підшлунковій залозі після її резекції із застосуванням електрохірургічних інструментів

Мета. Визначити особливості морфологічних змін у підшлунковій залозі (ПЗ) після резекційних втручань із застосуванням високоенергетичних електрохірургічних інструментів (ВЕЕХІ) та стандартної хірургічної техніки.
 Матеріали і методи. В умовах експерименту виконували резекцію ПЗ білим лабораторним щурам, використовуючи стандартну хірургічну техніку та ВЕЕХІ в режимі зварювання (DA2), біполярному та монополярному режимах. Гістологічно ПЗ досліджували безпосередньо після виконання операції та через 3, 7 і 21 добу, застосовуючи світлооптичний мікроскоп Leica DМ500.
 Результати. Після застосування стандартної хірургічної техніки в ранні строки виникало більш виражене запалення та швидше збільшувався об’єм новоутвореної сполучної тканини, ніж після використання електрохірургічних методів. Після всіх видів електрорезекції в новоутвореній тканині формувались протоки, чого не спостерігали після використання стандартної техніки. Після біполярного зварювання резектована поверхня мала менше крововиливів, ніж після використання хірургічних ножиць. Після резекції, виконаної з використанням монополярного зварювання, утворювався менш щільний коагуляційний прошарок, ніж після резекції, виконаної з використанням біполярного зварювання, а через 21-у добу в зоні резекції формувався значно більший об’єм сполучної тканини та зберігалися більш виражені ознаки запалення, ніж після використання біполярного методу.
 Висновки. У разі використання всіх видів електрорезекції скорочується тривалість виконання оперативного втручання, зменшується ризик виникнення кровотечі, на резектованій поверхні утворюється герметичне з’єднання, не ускладнюючи процесів відновлення.

LASER EN-BLOC RESECTION OF NON-MUSCLE-INVASIVE BLADDER CANCER: CLINICAL AND MORPHOLOGICAL SPECIFICITIES

Objectives to enhance the morphological diagnostic complex in order to predict postoperative outcomes in a more accurate way and to optimize patients with non-muscular invasive bladder cancer treatment.Materials and methods. The study included 34 patients from 25 to 71 years old underwent laser en-block resection, the most of them were males – 28. In 9 cases multiple carcinomas (2 or more) were found. Huge tumors (2 cm or more in one dimension) were resected in 6 patients. Results. The major part of tumors removed (n = 22) histologically appeared to be papillary urothelial carcinomas with low grade of malignancy and PUNLMP; in 6 cases G2 was verified, one tumor with high malignancy potention – G3. In 3 patients intramuscular invasion was found (invasive carcinoma T2) excluding them from the study.Discussion. Laser en-block resection of non-muscle-invasive bladder cancer appears to be the most optimal approach in operative treatment that provides representative histological material. For correct morphological estimate we recommend either to expand the resection zone to 1 cm which allows to remove circular resection margin or to take extra pinch biopsy from tumor crater (vertical margin). In 3 patients from our study positive circular margin was revealed histologically whereas foci of perineural and perivascular invasion were found in one case. A new subgrading of stage T1 depending on intramuscular invasion depth was suggested whereas the main criteria is the muscularis mucosae involvement.Conclusion. Morphological estimate of circular resection margin provides an ability to predict postoperative outcomes and correct the treatment in one or another way. Subgrading for T1-stage tumors is recommended for following correct postoperative prognosis and possibility of tumor recurrence.

Nonictal EEG biomarkers for diagnosis and treatment.

SummaryThere are no reliable nonictal biomarkers for epilepsy, electroencephalography (EEG) or otherwise, but efforts to identify biomarkers that would predict the development of epilepsy after a potential epileptogenic insult, diagnose the existence of epilepsy, or assess the effects of antiseizure or antiepileptogenic interventions are relying heavily on electrophysiology. The most promising EEG biomarkers to date are pathologic high‐frequency oscillations (pHFOs), brief EEG events in the range of 100 to 600 Hz, which are believed to reflect summated action potentials from synchronously bursting neurons. Studies of patients with epilepsy, and experimental animal models, have been based primarily on direct brain recording, which makes pHFOs potentially useful for localizing the epileptogenic zone for surgical resection, but application for other diagnostic and therapeutic purposes is limited. Consequently, recent efforts have involved identification of HFOs recorded with scalp electrodes, and with magnetoencephalography, which may reflect the same pathophysiologic mechanisms as pHFOs recorded directly from the brain. The search is also on for other EEG changes that might serve as epilepsy biomarkers, and candidates include arcuate rhythms, which may reflect repetitive pHFOs, reduction in theta rhythm, which correlates with epileptogenesis in several rodent models of epilepsy, and shortened sleep spindles that correlate with ictogenesis.

Impact of the resection method on the structure–functional changes in pancreatic gland

Objective. To compare the changes in pancreatic tissues after еxperimental operative interventions, performed, using standard surgical technique and electric welding.
 Маterials and methods. In experimental conditions a pancreatic resection was performed on laboratory animals – white rats, using standard surgical technique and electrocoagulator «Patommed ЕКVZ-300» in a welding regime. Pancreatic tissue was investigated immediately and in 3, 7 and 21 days after the operation.
 Results. After resection, performed using standard surgical procedure, alternative changes have occurred, which were accompanied by circulatory disorders around foci of destruction in pancreatocytes, and the process progressing in a cascade-like character with formation of the colliquative necrosis foci. Partial restoration of functional state of parenchymatous cells with moderate reduction of a stromal signs of inflammation and microvascular reaction were observed on the 21-st day.
 In the resection zone immediately after the electric welding conduction the tissue have had condensed due to the liquid compression and evaporation. But, on the 3-d and 7-th day a square of a necrotic parenchymatous damage due to thermal affection was lesser, then after application of a standard technique. The coagulation necrosis area, created as a result of a thermal impact, had reduced in size due to restoration by connective tissue and resorption by macrophages.
 Conclusion. After applying of a standard surgical technique in early terms a more expressed inflammation have had occurred with a neutrophil infiltration predominance and more volume of a newly created connective tissue grown, than after electric welding, what might lead later to formation of cicatricial tissue in large volume. After the electric welding performance in a newly formatted tissue the ducts have evolved, what was not observed after usage of a standard surgical technique.

Histological Characterization of the Irritative Zones in Focal Cortical Dysplasia Using a Preclinical Rat Model.

Current clinical practice in focal epilepsy involves brain source imaging (BSI) to localize brain areas where from interictal epileptiform discharges (IEDs) emerge. These areas, named irritative zones, have been useful to define candidate seizures-onset zones during pre-surgical workup. Since human histological data are mostly available from final resected zones, systematic studies characterizing pathophysiological mechanisms and abnormal molecular/cellular substrates in irritative zones—independent of them being epileptogenic—are challenging. Combining BSI and histological analysis from all types of irritative zones is only possible through the use of preclinical animal models. Here, we recorded 32-channel spontaneous electroencephalographic data from rats that have focal cortical dysplasia (FCD) and chronic seizures. BSI for different IED subtypes was performed using the methodology presented in Bae et al. (2015). Post-mortem brain sections containing irritative zones were stained to quantify anatomical, functional, and inflammatory biomarkers specific for epileptogenesis, and the results were compared with those obtained using the contralateral healthy brain tissue. We found abnormal anatomical structures in all irritative zones (i.e., larger neuronal processes, glioreactivity, and vascular cuffing) and larger expressions for neurotransmission (i.e., NR2B) and inflammation (i.e., ILβ1, TNFα and HMGB1). We conclude that irritative zones in this rat preclinical model of FCD comprise abnormal tissues disregarding whether they are actually involved in icto-genesis or not. We hypothesize that seizure perpetuation happens gradually; hence, our results could support the use of IED-based BSI for the early diagnosis and preventive treatment of potential epileptic foci. Further verifications in humans are yet needed.

F162. Lesion-Constrained Electrical Source Imaging (LC-ESI) in epilepsy surgery for tuberous sclerosis complex: A pilot study

Tuberous Sclerosis Complex (TSC) is a genetic neurocutaneous disorder associated with multiple dysplastic lesions called tubers. Neurologically, up to 60% of children with TSC have refractory epilepsy, and are at risk for poor neurological outcome. In these patients epilepsy surgery should be explored, the success of which hinges on the identification of the epileptogenic tuber. Electrical source imaging (ESI) models the cerebral origin of scalp EEG data. In TSC, ESI can yield ambiguous results as the distributed source solution is typically constrained to the cortex, whereas the epileptogenic zone is in subcortical tubers. We tested the clinical utility of lesion-constrained electrical source imaging (LC-ESI) in epilepsy surgery in six children with TSC. LC-ESI is based on a proposed head model in which the source solution is constrained to multiple lesions, rather than to the cortical ribbon. We performed LC-ESI on the ictal and interictal EEG data from the presurgical workup of six patients with TSC. In addition, tubers were expanded in 3 directions to include an 8 mm perituber rim as a potential seizure onset zone. We used a goodness of fit analysis to quantify the ability of individual tubers to approximate the measured EEG data. Tubers were rank-ordered, and color-coded to determine the overlap of the LC-ESI solution maximum with the surgical resection cavity, in the context of surgical outcome. Comparison was made to Low Resolution Brain Electromagnetic Tomography (LORETA). Patients were grouped according to good outcome (Engel Class I or II, n = 3), and poor outcome (Engel Class III or IV, n = 3). LORETA predicted the surgical cavity in 1 patient with good outcome (true positive), and had a positive predictive value of 50% and 100% for interictal and ictal data, respectively. Due to a high number of false negatives (source outside of the cavity in patients with a good outcome), the negative predictive value was only 40% and 60% for interictal and ictal data, respectively. LC-ESI identified individual tubers concordant with the resection cavity in 2 (interictal, PPV 66%), and 3 (ictal, PPV 100%) out of 3 patients with a good outcome. Epileptogenic tubers were identified correctly outside of the resection cavity in 2 (interictal, NPV 66%) and 3 (ictal, NPV 100%) out of 3 patients with a poor outcome, where the resection did not include the epileptogenic tubers. There was no difference between solutions constrained to tubers only as compared to those also incorporating a perituber rim. This pilot study supports clinical utility of LC-ESI in the presurgical workup for patients with TSC. Ictal data was more accurate than interictal data in all models. The epileptogenic tuber identified by LC-ESI was concordant with the resection zone in patients with a good surgical outcome, and appropriately discordant in patients with a poor outcome. LC-ESI outperformed conventional LORETA, but further validation is required.

S127. Computer aided evaluation of intracerebral depth electrode recordings by automatic seizure detection

Introduction Preoperative evaluation of patients with medically intractable epilepsies requires accurate localization of the epileptogenic zone. Intracerebral depth electrodes are used to asses regions of interest and to enclose the resection zone during presurgical planning. Often a high number of needles is needed to accurately define the resection volume. Manual evaluation of these prolonged recordings including a large number of channels which is highly time consuming. To raise efficiency we developed a computer algorithm for automatic detection of epileptic seizures in depth electrode recordings. Primary goal was to detect seizures with high sensitivity without the need to set patient specific parameters. Methods The automatic seizure detection algorithm for depth electrode data was based on an existing seizure detection algorithm for surface EEG. Evaluation of the frequency and amplitude range was extended to allow detection of ictal activity of up to 25 Hz and amplitudes of up to 1 mV. To reduce the number of false detections a method to recognize loose contacts was implemented. For clinical validation, recordings of 11 patients that underwent depth electrode investigation in the Academic Centre of Epileptology, Kempenhaeghe were utilized. Recordings were evaluated manually by clinical neurophysiologists and seizures were annotated. For 10 patients the first 24 h of their depth electrode recording were analyzed, yielding in total 23 seizures detected for five of the patients studied. For one patient the complete recording was analyzed with a duration of 138 h, yielding 36 seizures. Manual seizure annotations were compared to computer detections for assessment of sensitivity and false detection rate. Results The automatic seizure detection algorithm found 84% of all seizures on average. All or more than 80% of the seizures were detected in the first 24 h of 10 patients. Analysis of the complete patient recording showed suppressed seizure onset activity of less than 2 s duration followed by paroxysmal fast activity. In this patient 14 out of the 36 seizures that evolved into a rhythmic ictal pattern were detected. The average false detection rate was 15 false detections in 24 h. Validation showed that most of the false positives either point to interictal activity or to background alpha activity. Conclusion We proposed a computer aided workflow for evaluation of depth electrode recordings. Our automatic seizure detection algorithm was able to detect either all or more than 7 seizures of a patient which allows deduction of important medical findings. The low false detection rate facilitates fast review of data. Our proposed approach showed that automatic evaluation of seizure activity in depth electrode recordings is feasible and will raise the overall efficiency of diagnostic.

Resection of Medial Talocalcaneal Coalition With Interposition of a Pediculated Flap of Tibialis Posterior Tendon Sheath.

The purpose of the study was to present a novel operative technique in the management of medial talocalcaneal coalition (TC) and to report our clinical and radiologic results after interposition of a pediculated flap (PF) of the tibialis posterior tendon sheath. Twelve feet of 10 patients with a medial TC were treated with the interposition of PF of the tibialis posterior tendon sheath following resection. Pre- and postoperative clinical examinations were performed to evaluate the range of motion and the function of the tibialis posterior muscle of the affected foot. Pain was registered by visual analog scale (VAS) and the function of the foot by the American Orthopaedic Foot & Ankle Society (AOFAS) hindfoot score. The mean follow-up duration was 57.2 months (SD ±37.2 range 12-128) after surgery. Magnetic resonance imaging (MRI) was carried out to assess the outcome. All patients reported a significant reduction of pain ( P = .002) at the final follow-up. The activity level had improved since the operation, and the subtalar joint motion was increased, but no weakness of the tibialis posterior muscle could be observed. The AOFAS hindfoot score was significantly improved ( P = .002). MRI did not reveal any migration of the tibialis posterior tendon sheath, and the interposed PF was confirmed at the resection zone. Furthermore, no TC relapse or ruptures of the functional anatomical structures could be observed. The resection combined with the interposition of a PF of the tendon sheath seems to avoid relapse of TC and improves symptoms and the function of the foot. Level IV, case series.

On the optimal z-score threshold for SISCOM analysis to localize the ictal onset zone

BackgroundIn epilepsy patients, SISCOM or subtraction ictal single photon emission computed tomography co-registered to magnetic resonance imaging has become a routinely used, non-invasive technique to localize the ictal onset zone (IOZ). Thresholding of clusters with a predefined number of standard deviations from normality (z-score) is generally accepted to localize the IOZ. In this study, we aimed to assess the robustness of this parameter in a group of patients with well-characterized drug-resistant epilepsy in whom the exact location of the IOZ was known after successful epilepsy surgery. Eighty patients underwent preoperative SISCOM and were seizure free in a postoperative period of minimum 1 year. SISCOMs with z-threshold 2 and 1.5 were analyzed by two experienced readers separately, blinded from the clinical ground truth data. Their reported location of the IOZ was compared with the operative resection zone. Furthermore, confidence scores of the SISCOM IOZ were compared for the two thresholds.ResultsVisual reporting with a z-score threshold of 1.5 and 2 showed no statistically significant difference in localizing correspondence with the ground truth (70 vs. 72% respectively, p = 0.17). Interrater agreement was moderate (κ = 0.65) at the threshold of 1.5, but high (κ = 0.84) at a threshold of 2, where also reviewers were significantly more confident (p < 0.01).ConclusionsSISCOM is a clinically useful, routinely used modality in the preoperative work-up in many epilepsy surgery centers. We found no significant differences in localizing value of the IOZ using a threshold of 1.5 or 2, but interrater agreement and reader confidence were higher using a z-score threshold of 2.