Impaired awareness in mesial temporal lobe epilepsy: Network analysis of foramen ovale and scalp EEG.

OBJECTIVE: We use co-registration of foramen-ovale and scalp-EEG to investigate network alterations in temporal-lobe epilepsy during focal seizures without (aura) or with impairment of awareness (SIA). METHODS: One aura and one SIA were selected from six patients. Temporal dynamic among 4 epochs, as well as the differences between aura and SIA, were analyzed through partial directed coherence and graph theory-based indices of centrality. RESULTS: Regarding the auras temporal evolution, fronto-parietal (FP) regions showed decreased connectivity with respect to the interictal period, in both epileptogenic (EH) and non-epileptogenic hemisphere (nEH). During SIAs, temporal dynamic showed more changes than auras: centrality of mesial temporal (mT) regions changes during all conditions, and nEH FP centrality showed the same dynamic trend of the aura (decreased centrality), until the last epoch, close to the impaired awareness, when showed increased centrality. Comparing SIA with aura, in proximity of impaired awareness, increased centrality was found in all the regions, except in nEH mT. CONCLUSIONS: Our findings suggested that the impairment of awareness is related to network alterations occurring first in neocortical regions and when awareness is still retained. SIGNIFICANCE: The analysis of 'hub' alteration can represent a suitable biomarker for scalp EEG-based prediction of awareness impairment.

Highly consistent temporal lobe interictal spike networks revealed from foramen ovale electrodes.

OBJECTIVE: A major challenge that limits understanding and treatment of epileptic events from mesial temporal structures comes from our inability to detect and map interictal networks reproducibly using scalp electrodes. Here, we developed a novel approach to map interictal spike networks and demonstrate their relationships to seizure onset and lesions in patients with foramen ovale electrode implantations. METHODS: We applied the direct Directed Transfer Function to reveal interictal spike propagation from bilateral foramen ovale electrodes on 10 consecutive patients and co-registered spatially with both seizure onset zones and temporal lobe lesions. RESULTS: Highly reproducible, yet unique interictal spike networks were seen for each patient (correlation: 0.93 ±â€¯0.13). Interictal spikes spread in both anterior and posterior directions within each temporal lobe, often reverberating between sites. Spikes propagated to the opposite temporal lobe predominantly through posterior pathways. Patients with structural lesions (N = 4), including tumors and sclerosis, developed reproducible spike networks adjacent to their lesions that were highly lateralized compared to patients without lesions. Only 5% of mesial temporal lobe spikes were time-locked with scalp electrode spikes. Our preliminary observation on two lesional patients suggested that along with lesion location, Interictal spike networks also partially co-registered with seizure onset zones suggesting interrelationship between seizure onset and a subset of spike networks. CONCLUSIONS: This is the first demonstration of patient-specific, reproducible interictal spike networks in mesial temporal structures that are closely linked to both temporal lobe lesions and seizure onset zones. SIGNIFICANCE: Interictal spike connectivity is a novel approach to map epileptic networks that could help advance invasive and non-invasive epilepsy treatments.

Fetal echocardiographic predictors of biventricular circulation in hypoplastic left heart complex.

OBJECTIVES: To determine which echocardiographic features of hypoplastic left heart complex (HLHC) in the fetal period are predictive of biventricular (BV) circulation and to evaluate the long-term outcome of patients with HLHC, including rates of mortality, reintervention and development of further cardiac disease. METHODS: Echocardiograms of fetuses with HLHC obtained at 18-26 weeks and 27-36 weeks' gestation between 2004 and 2017 were included in the analysis. The primary outcome was successful BV circulation (Group 1). Group 2 included patients with single-ventricle palliation, death or transplant. Univariate analysis was performed on data obtained at 18-26 and 27-36 weeks and multivariate logistic regression was performed on data obtained at 27-36 weeks only. RESULTS: Of the 51 included cases, 44 achieved successful BV circulation (Group 1) and seven did not (Group 2). Right-to-left/bidirectional foramen ovale (FO) flow and a higher mitral valve (MV) annulus Z-score were associated with successful BV circulation on both univariate and multivariate analysis. Bidirectional or left-to-right FO flow, left ventricular length (LVL) Z-score of < -2.4 and a MV Z-score of < -4.5 correctly predicted 80% of Group 2 cases. Late follow-up was available for 41 patients. There were two late deaths in Group 2. Thirteen patients in Group 1 required reintervention, 12 developed mitral stenosis and five developed isolated subaortic stenosis. CONCLUSIONS: BV circulation is common in fetuses with HLHC. Higher MV annulus and LVL Z-scores and right to left direction of FO flow are important predictors of BV circulation. Long-term sequelae in those with BV circulation may include mitral and subaortic stenosis. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Urgent neonatal balloon atrial septostomy in simple transposition of the great arteries: predictive value of fetal cardiac parameters.

OBJECTIVES: To investigate the impact of abnormal perinatal loading conditions on cardiac geometry and function in term fetuses and neonates with transposition of the great arteries with intact interventricular septum (simple TGA), and to explore the predictive value of fetal cardiac parameters for an urgent balloon atrial septostomy (BAS) after birth. METHODS: This was a prospective longitudinal follow-up study of women delivering at term, including both uncomplicated pregnancies with normal outcome and pregnancies affected by fetal simple TGA. Conventional, spectral-tissue Doppler and speckle-tracking echocardiographic parameters were obtained within 1 week before delivery and within the first few hours after delivery. Neonates with simple TGA that required urgent BAS were assessed after the procedure and before corrective arterial switch surgery. Cardiac parameters were normalized by cardiac cycle length, ventricular end-diastolic length or end-diastolic dimension, as appropriate. Fetal and neonatal cardiac parameters were compared between simple-TGA cases and controls, and perinatal changes in the simple-TGA group were assessed. Receiver-operating-characteristics (ROC)-curve analysis was used to assess the predictive value of fetal cardiac parameters for urgent BAS after birth in the simple-TGA group. RESULTS: A total of 67 pregnant women delivering at term were included in the study (54 normal pregnancies and 13 with a diagnosis of fetal simple TGA). Compared with normal term fetuses, term fetuses with simple TGA exhibited more globular hypertrophied ventricles, increased biventricular systolic function and diastolic dysfunction (right ventricular (RV) sphericity index (SI), 0.58 vs 0.54; left ventricular (LV)-SI, 0.55 vs 0.49; combined cardiac output (CCO), 483 vs 406 mL/min/kg; LV torsion, 4.3 vs 3.0 deg/cm; RV isovolumetric relaxation time (IVRT'), 127 vs 102 ms; P < 0.01 for all). Compared with normal neonates, neonates with simple TGA demonstrated biventricular hypertrophy, a more spherical right ventricle and altered systolic and diastolic functional parameters (RV-SI, 0.61 vs 0.43; RV myocardial performance index, 0.47 vs 0.34; CCO, 697 vs 486 mL/min/kg; LV-IVRT', 100 vs 79 ms; RV-IVRT', 106 vs 71 ms; P < 0.001 for all). Paired comparison of neonatal and fetal cardiac indices in the simple-TGA group showed persistence of the fetal phenotype, increased biventricular systolic myocardial contractility and CCO, and diastolic dysfunction (RV systolic myocardial velocity (S'), 0.31 vs 0.24 cm/s; LV-S', 0.23 vs 0.18 cm/s; CCO, 697 vs 483 mL/min/kg; LV torsion, 1.1 vs 4.3 deg/cm; P < 0.001 for all). Several fetal cardiac parameters in term fetuses with simple TGA demonstrated high predictive value for an urgent BAS procedure after birth. Our proposed novel fetal cardiac index, LV rotation-to-shortening ratio, as a potential marker of subendocardial dysfunction, for a cut-off value of ≥ 0.23, had an area under the ROC curve (AUC) of 0.94, sensitivity of 100% and specificity of 83%. For RV/LV end-diastolic area ratio ≥ 1.33, pulmonary-valve-to-aortic-valve-dimension ratio ≤ 0.89, RV/LV cardiac output ratio ≥ 1.38 and foramen-ovale-dimension-to-total-interatrial-septal-length ratio ≤ 0.27, AUC was 0.93-0.98, sensitivity was 86% and specificity was 83-100% for all. CONCLUSIONS: Simple-TGA fetuses exhibited cardiac remodeling at term with more profound alterations in these cardiac parameters after birth, suggestive of adaptation to abnormal loading conditions and possible adaptive responses to hypoxemia. Perinatal adaptation in simple TGA might reflect persistence of the abnormal parallel arrangement of cardiovascular circulation and the presence of widely patent fetal shunts imposing volume load on the neonatal heart. The fetal cardiac parameters that showed high predictive value for urgent BAS after birth might reflect the impact of late-gestation pathophysiology and progressive hypoxemia on fetal cardiac geometry and function in simple TGA. If these findings are validated in larger prospective studies, detailed cardiac assessment of fetuses with simple TGA near term could facilitate improvements in perinatal management and refinement of the timing of postnatal intervention strategies to prevent adverse pregnancy outcomes. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Papel de la radiología en el síndrome de pseudotumor cerebral / Role of Imaging in pseudotumor cerebri syndrome

El síndrome de pseudotumor cerebral (SPTC) es una alteración caracterizada por el aumento de presión intracraneal que afecta predominantemente a mujeres jóvenes obesas. El objetivo del trabajo es definir los conceptos de SPTC primario, sin causa identificable y denominado también hipertensión intracraneal idiopática (HII), y de SPTC secundario, con etiología identificable. Se revisa el papel actual de las pruebas de imagen en su diagnóstico y los hallazgos por imagen típicos del SPTC, algunos de los cuales se incluyen entre los criterios diagnósticos propuestos en 2013. También se remarca el papel fundamental de la radiología intervencionista en el tratamiento, puesto que la colocación de stent en las estenosis de senos venosos constituye una alternativa terapéutica novedosa en pacientes resistentes al tratamiento clásico. Por último, se describen aquellos biomarcadores de imagen que han sido evaluados para aproximar el diagnóstico de la HII y predecir la respuesta al tratamiento

Pseudotumor cerebri is a disorder characterized by increased intracranial pressure that predominantly affects obese young women. This paper aims to define the concepts of primary pseudotumor cerebri, in which the cause cannot be identified (also known as idiopathic intracranial hypertension), and secondary pseudotumor cerebri, in which the cause can be identified. We review the current role of imaging techniques in diagnosing pseudotumor cerebri and describe and illustrate the most characteristic imaging findings of the disorder, some of which are included in the diagnostic criteria proposed in 2013. We also consider the fundamental role of interventional radiology in the treatment of pseudotumor cerebri because placing a stent in stenosed venous sinuses is a novel treatment option in patients who are refractory to classical treatment. Finally, we describe the imaging biomarkers that have been evaluated for diagnosing primary pseudotumor cerebri and predicting the response to treatment

Presumed prenatal closure of foramen ovale and persistent pulmonary hypertension of the newborn.

Prenatal closure of foramen ovale without CHD is a rarely reported entity. Therefore, clinical and echocardiographic findings are poorly defined in these patients. We report a patient with prenatal closure of foramen ovale that presented with severe pulmonary hypertension of the newborn and left ventricular failure. Judicious management strategies were utilised to successfully treat both life-threatening conditions.

Detection of mesial temporal lobe epileptiform discharges on intracranial electrodes using deep learning.

OBJECTIVE: Develop a high-performing algorithm to detect mesial temporal lobe (mTL) epileptiform discharges on intracranial electrode recordings. METHODS: An epileptologist annotated 13,959 epileptiform discharges from a dataset of intracranial EEG recordings from 46 epilepsy patients. Using this dataset, we trained a convolutional neural network (CNN) to recognize mTL epileptiform discharges from a single intracranial bipolar channel. The CNN outputs from multiple bipolar channel inputs were averaged to generate the final detector output. Algorithm performance was estimated using a nested 5-fold cross-validation. RESULTS: On the receiver-operating characteristic curve, our algorithm achieved an area under the curve (AUC) of 0.996 and a partial AUC (for specificity > 0.9) of 0.981. AUC on a precision-recall curve was 0.807. A sensitivity of 84% was attained at a false positive rate of 1 per minute. 35.9% of the false positive detections corresponded to epileptiform discharges that were missed during expert annotation. CONCLUSIONS: Using deep learning, we developed a high-performing, patient non-specific algorithm for detection of mTL epileptiform discharges on intracranial electrodes. SIGNIFICANCE: Our algorithm has many potential applications for understanding the impact of mTL epileptiform discharges in epilepsy and on cognition, and for developing therapies to specifically reduce mTL epileptiform activity.

[Intrauterine restrictive foramen ovale: cause of neonatal pulmonary hypertension]. / Foramen oval restrictivo intraútero: causa de hipertensión pulmonar neonatal.

Premature closure of the foramen ovale (FO) or intrauterine restrictive FO is a rare entity of unknown etiology. This pathology is associated with an elevated risk of pulmonary hypertension, which can cause congestive heart failure with hydrops and fetal death. Patients with restrictive intrauterine FO may develop left ventricle diastolic dysfunction and pulmonary edema. A newborn with increased right cavities in the prenatal ultrasound is presented. In postnatal echocardiogram, dilatation of right cavities was confirmed with pulmonary hypertension in the systemic range and immobile interatrial septum with closed FO. After 9 days of persistent respiratory distress, an echocardiogram was performed with improvement of pulmonary hypertension but with mild biventricular and diastolic and systolic dysfunction of the left ventricle with pulmonary edema. Diuretic treatment was decided, with normalization of ventricular function.

El cierre prematuro del foramen oval o foramen oval restrictivo intraútero es una entidad rara de etiología desconocida. Dicha patología se asocia a un riesgo elevado de hipertensión pulmonar y puede ocasionar insuficiencia cardíaca congestiva con hidrops y muerte fetal. También, se puede asociar con disfunción diastólica en el período neonatal. Se presenta a un recién nacido en el que, en una ecografía prenatal, se visualizó un aumento de las cavidades derechas. En el ecocardiograma posnatal, se confirmó la dilatación de las cavidades derechas con hipertensión pulmonar en rango sistémico y septo interauricular inmóvil con foramen oval cerrado. A los 9 días, ante la persistencia de dificultad respiratoria, se realizó un ecocardiograma, con mejoría de la hipertensión pulmonar, pero con disfunción sistólica biventricular leve y diastólica del ventrículo izquierdo con edema pulmonar. Se indicó el tratamiento diurético, con normalización de la función ventricular.

Provocative maneuvers to improve patent foramen ovale detection: A brief review of the literature.

Patent foramen ovale (PFO) is the most common type of inter-atrial shunt, with prevalence as high as 30%. Detection of PFO has implications in patients with stroke, peripheral embolism, decompression illness, and other conditions. Transesophageal echo (TEE) with saline contrast injection is the current standard for PFO detection, but even with TEE, PFOs are sometimes missed. With advances in percutaneous PFO closure therapies and proven long-term benefit of closure, accurate PFO detection takes on cardinal importance. Various provocative maneuvers to enhance PFO detection are in clinical use and have been studied. The Valsalva maneuver has long-held position as the ideal provocation to unmask PFO, but other maneuvers such as cough, sniff, Müller's, and more have gained relevance. In this article, we will examine various maneuvers and discuss their utility in PFO detection.

Prenatal diagnosis of congenital absence of aortic valve associated with restrictive foramen ovale: Hemodynamic features and clinical outcome.

We present the case of a fetus with absent aortic valve (AAV), mitral regurgitation (MR), and restrictive foramen ovale (FO) who survived in utero but died of severe hypoxia after birth. We reported previously two cases of "inverse circulatory shunt" in AAV with MR, that is, blood from the ascending aorta flowing into the left ventricle through aortic regurgitation, to the left atrium due to MR, to the right atrium through FO, to the right ventricle, then to the pulmonary arteries, and to the ascending aorta through the ductus. In the present case, restrictive FO prevented inverse circulatory shunt, but resulted in postnatal death.

Inspiratory and expiratory resistance cause right-to-left bubble passage through the foramen ovale.

A patent foramen ovale (PFO) is linked to increased risk of decompression illness in divers. One theory is that venous gas emboli crossing the PFO can be minimized by avoiding lifting, straining and Valsalva maneuvers. Alternatively, we hypothesized that mild increases in external inspiratory and expiratory resistance, similar to that provided by a SCUBA regulator, recruit the PFO. Nine healthy adults with a Valsalva-proven PFO completed three randomized trials (inspiratory, expiratory, and combined external loading) with six levels of increasing external resistance (2-20 cmH2 O/L/sec). An agitated saline contrast echocardiogram was performed at each level to determine foramen ovale patency. Contrary to our hypothesis, there was no relationship between the number of subjects recruiting their PFO and the level of external resistance. In fact, at least 50% of participants recruited their PFO during 14 of 18 trials and there was no difference between the combined inspiratory, expiratory, or combined external resistance trials (P > 0.05). We further examined the relationship between PFO recruitment and intrathoracic pressure, estimated from esophageal pressure. Esophageal pressure was not different between participants with and without a recruited PFO. Intrasubject variability was the most important predictor of PFO patency, suggesting that some individuals are more likely to recruit their PFO in the face of even mild external resistance. Right-to-left bubble passage through the PFO occurs in conditions that are physiologically relevant to divers. Transthoracic echocardiography with mild external breathing resistance may be a tool to identify divers that are at risk of PFO-related decompression illness.

Echocardiographic features of PFOs and paradoxical embolism: a complicated puzzle.

Patent foramen ovale (PFO) is a residual, oblique, slit or tunnel like communication in the atrial septum that persists into adulthood. It is usually an incidental finding with no clinical repercussions. Nevertheless, recent evidence supports the association between the presence of a PFO and a number of clinical conditions, most notably cryptogenic stroke (CS). There is enough evidence that paradoxical embolism is a mechanism which can explain this association. Patient characteristics and certain echocardiography-derived anatomical and hemodynamic features of PFO provide great assistance in estimating the probability of paradoxical embolism. In this review, we initially describe PFO embryology and anatomy. We extensively present the available data on clinical, anatomical and hemodynamic features of PFOs which have been correlated with increased likelihood of paradoxical embolism and recent evidence of therapeutic management.

Atrial myxoma in a patient with patent foramen ovale: evaluation with multimodal imaging. Case report / Mixoma auricular en un paciente con foramen oval permeable: evaluación con imágenes multimodales. Reporte de un caso

Abstract: Primary cardiac tumors in adults are rare and mostly benign, approximately 75%, being the myxoma the most frequent in half of that percentage. One-fourth of the primary cardiac tumors are malignant and 95% of the cases are sarcomas. Metastases are more frequent than primary tumors. Cardiac surgery is indicated specially in benign masses and therapies such as chemotherapy and/or radiotherapy should be reserved for unresectable or metastatic malignancies. Hence the importance of a diagnostic approach, which leads to the best therapeutic conduct and in many cases, a multimodal image approach is necessary, as it is exposed in our case.(AU)

Resumen: Los tumores cardiacos primarios en adultos son raros y en su mayoría benignos, aproximadamente el 75%, siendo el mixoma el más frecuente en la mitad de ese porcentaje. Un cuarto de los tumores cardiacos primarios son malignos y el 95% de los casos son sarcomas. Las metástasis son más frecuentes que los tumores primarios. La cirugía cardiaca está indicada especialmente en masas benignas y las terapias como la quimioterapia y/o la radioterapia deben reservarse para tumores malignos o metástasis irresecables. De ahí la importancia de un enfoque de diagnóstico, que conduzca a la mejor conducta terapéutica y, en muchos casos, es necesario un enfoque de imagen multimodal, como está expuesto en nuestro caso.(AU)

Transthoracic contrast echocardiography using vitamin B6 and sodium bicarbonate as contrast agents for the diagnosis of patent foramen ovale.

To evaluate the utility of transthoracic contrast echocardiography (cTTE) using vitamin B6 and sodium bicarbonate as contrast agents for diagnosing right-to-left shunt (RLS) caused by patent foramen ovale (PFO) compared to that of transesophageal echocardiography (TEE). We investigated 125 patients admitted to our neurology department with unexplained cerebral infarction and migraine. All patients underwent cTTE using vitamin B6 and sodium bicarbonate as contrast agents, after which they underwent transthoracic echocardiography. The Doppler signal was recorded during the Valsalva maneuver, and TEE examinations were performed. The feasibility, diagnostic sensitivity, and safety of cTTE and TEE for PFO recognition were compared. Evidence of PFO was found in 49 (39.20%) patients with cTTE, more than were detected with TEE (39, 31.20%) (χ2=5.0625, P=0.0244). cTTE had a sensitivity of 92.31% and a specificity of 84.88% for diagnosing PFO, showing high concordance with TEE for PFO recognition (κ=0.72). Further, results of a semi-quantitative evaluation of PFO-RLS by cTTE were better than those with TEE (Z=-2.011, P=0.044). No significant adverse reaction was discovered during cTTE examination. cTTE using vitamin B6 and sodium bicarbonate as contrast agents has relatively good sensitivity and specificity for diagnosing RLS caused by PFO when compared with those for TEE. Using vitamin B6 and sodium bicarbonate as contrast agents to perform cTTE is recommended for detecting and diagnosing the PFO due to its simplicity, non-invasive character, low cost, and high feasibility.

Platypnea-Orthodeoxia Syndrome: A Case of Chronic Paroxysmal Hypoxemia.

A 75-year-old man with chronic (30-year) unexplained paroxysmal hypoxemia presented with postural hypoxemia and desaturation consistent with a clinical manifestation of platypnea-orthodeoxia syndrome. His history included a lack of significant past pulmonary disease, yet with intermittent need for oxygen supplementation. On admission he was found to have an interatrial shunt through a patent foramen ovale. Device closure by percutaneous catheterization led to sustained resolution of symptoms. Platypnea-orthodeoxia syndrome is a rare but important consideration in the differential diagnosis of hypoxemia, as it represents a potentially curable cause of hypoxemia, with missed diagnosis leading to possible patient morbidity if untreated. Even more importantly, an astute and careful history and physical examination are integral to the diagnosis of this rare but likely under-recognized syndrome.

Hipoxemia grave por shunt derecha-izquierda a través del foramen oval en ausencia de hipertensión pulmonar. Existe y se puede tratar con éxito / Patent Foramen Ovale Causing Severe Hypoxemia Due to Right-to-left Shunting in Patients Without Pulmonary Hypertension. Clinical Suspicion Clues for Diagnosis and Treatment

No disponible

Diagnostic ultrasound features and outcome of restrictive foramen ovale in fetuses with structurally normal hearts.

Intrauterine foramen ovale (FO) restriction in association with congenital heart disease (CHD) carries a poor prognosis. However, in the absence of CHD, the clinical importance of restrictive FO in the fetus is not well understood. We evaluated the antenatal prevalence, clinical presentation, diagnostic ultrasound features, and outcome of restrictive FO in fetuses without CHD. We reviewed the echocardiographic and clinical records of 23 fetuses diagnosed with a restrictive FO and structurally normal heart between 2001 and 2012. The atrial septum, dimensions of cardiac structures, left and right cardiac output and Doppler interrogation of cardiac flows were examined. The clinical outcomes of all fetuses with restrictive FO were analysed. Restrictive FO was identified in 23 of 1,682 (1.4%) fetuses with no CHD. Enlarged right heart structures (100%), hypermobile or redundant primum atrial septum (91%), increased right-to-left ventricular cardiac output ratio (91%), and posteriorly angulated ductus arteriosus (68%) were the most common echocardiographic findings associated with this rare phenomenon. Additional noncardiac systemic abnormalities were identified in 13 (56%) babies. Seven (30%) neonates developed persistent pulmonary hypertension, and 7 infants died. Antenatal restrictive FO is an underrecognised entity despite being a common cause of right heart dilatation in the fetus. In the absence of CHD, restrictive FO is well tolerated antenatally, but its frequent association with noncardiac abnormalities and pulmonary hypertension in the neonate are noteworthy.

Utility of foramen ovale electrodes in mesial temporal lobe epilepsy.

OBJECTIVES: To determine the ability of foramen ovale electrodes (FOEs) to localize epileptogenic foci after inconclusive noninvasive investigations in patients with suspected mesial temporal lobe epilepsy (MTLE). METHODS: We identified patients with medically intractable epilepsy who had undergone FOE investigation for initial invasive monitoring at our institution between 2005 and 2012. Indications for initiating FOE investigation were grouped into four categories: (1) bilateral anterior temporal ictal activity on scalp electroencephalography (EEG), (2) unclear laterality of scalp EEG onset due to muscle artifact or significant delay following clinical manifestation, (3) discordance between ictal and interictal discharges, and (4) investigation of a specific anatomic abnormality or competing putative focus. The FOE investigation was classified as informative if it provided sufficient evidence to make a treatment decision. RESULTS: Forty-two consecutive patients underwent FOE investigation, which was informative in 38 patients (90.5%). Of these 38 patients, 24 were determined to be appropriate candidates for resective surgery. Five were localized sufficiently for surgery, but were considered high risk for verbal memory deficit, and nine were deemed poor surgical candidates because of bilateral ictal origins. The remaining 4 of 42 patients had inconclusive FOE studies and were referred for further invasive investigation. Of the 18 patients who underwent resective surgery, 13 (72%) were seizure-free (Engel class I) at last follow-up (mean 22.5 months). SIGNIFICANCE: More than 90% of our 42 FOE studies provided sufficient evidence to render treatment decisions. When undertaken with an appropriate hypothesis, FOE investigations are a minimally invasive and efficacious means for evaluating patients with suspected MTLE after an inconclusive noninvasive investigation.