Long-term seizure outcome after mesial temporal lobe epilepsy surgery: corticalamygdalohippocampectomy versus selective amygdalohippocampectomy

Current state of the art of traditional and minimal invasive epilepsy surgery approaches

Introduction

Open resective surgery remains the main treatment modality for refractory epilepsy, but is often considered a last resort option due to its invasiveness.

Research question

This manuscript aims to provide an overview on traditional as well as minimally invasive surgical approaches in modern state of the art epilepsy surgery.

Materials and methods

This narrative review addresses both historical and contemporary as well as minimal invasive surgical approaches in epilepsy surgery. Peer-reviewed published articles were retrieved from PubMed and Scopus. Only articles written in English were considered for this work. A range of traditional and minimally invasive surgical approaches in epilepsy surgery were examined, and their respective advantages and disadvantages have been summarized.

Results

The following approaches and techniques are discussed: minimally invasive diagnostics in epilepsy surgery, anterior temporal lobectomy, functional temporal lobectomy, selective amygdalohippocampectomy through a transsylvian, transcortical, or subtemporal approach, insulo-opercular corticectomies compared to laser interstitial thermal therapy, radiofrequency thermocoagulation, stereotactic radiosurgery, neuromodulation, high intensity focused ultrasound, and disconnection surgery including callosotomy, hemispherotomy, and subpial transections.

Discussion and conclusion

Understanding the benefits and disadvantages of different surgical approaches and strategies in traditional and minimal invasive epilepsy surgery might improve the surgical decision tree, as not all procedures are appropriate for all patients.

Hippocampal and neocortical BRAF mutant non-expansive lesions in focal epilepsies

OBJECTIVE

Mesial Temporal Lobe Epilepsy-associated Hippocampal Sclerosis (MTLE-HS) is a syndrome associated with various aetiologies. We previously identified CD34-positive extravascular stellate cells (CD34+ cells) possibly related to BRAFV600E oncogenic variant in a subset of MTLE-HS. We aimed to identify the BRAFV600E oncogenic variants and characterise the CD34+ cells.

METHODS

We analysed BRAFV600E oncogenic variant by digital droplet Polymerase Chain Reaction in 53 MTLE-HS samples (25 with CD34+ cells) and nine non-expansive neocortical lesions resected during epilepsy surgery (five with CD34+ cells). Ex vivo multi-electrode array recording, immunolabelling, methylation microarray and single nuclei RNAseq were performed on BRAFwildtype MTLE-HS and BRAFV600E mutant non-expansive lesion of hippocampus and/or neocortex.

RESULTS

We identified a BRAFV600E oncogenic variant in five MTLE-HS samples with CD34+ cells (19%) and in five neocortical samples with CD34+ cells (100%). Single nuclei RNAseq of resected samples revealed two unique clusters of abnormal cells (including CD34+ cells) associated with senescence and oligodendrocyte development in both hippocampal and neocortical BRAFV600E mutant samples. The co-expression of the oncogene-induced senescence marker p16INK4A and the outer subventricular zone radial glia progenitor marker HOPX in CD34+ cells was confirmed by multiplex immunostaining. Pseudotime analysis showed that abnormal cells share a common lineage from progenitors to myelinating oligodendrocytes. Epilepsy surgery led to seizure freedom in eight of the 10 patients with BRAF mutant lesions.

INTERPRETATION

BRAFV600E underlies a subset of MTLE-HS and epileptogenic non-expansive neocortical focal lesions. Detection of the oncogenic variant may help diagnosis and open perspectives for targeted therapies.

Microsurgery for drug resistance epilepsy due to temporal lobe lesions in a resource limited condition: a cross-sectional study

Epilepsy is a prevalent neurological condition that affects individuals of all ages and genders worldwide. Surgical intervention for drug-resistant epilepsy has been found to improve quality of life, with patient independence being of utmost importance.

METHODS

The study was a retrospective and prospective cross-sectional study of 35 cases of drug-resistant temporal lobe epilepsy. All patients were operated on by the primary author between May 2018 and September 2022. The study evaluated various factors including clinical characteristics, electroencephalogram, magnetic resonance imaging, surgical outcomes, and histopathology.

RESULTS

The success rate of the surgeries (74.3%) is similar to those reported in high-income countries. 51.4% underwent selective amygdalohippocampectomy for cases that localized to the mesial temporal lobe. Lateral/neocortical lesions underwent lesionectomy (48.6%). Our study found a complication rate of 17.1%: meningitis (8.5%), trainset focal paralysis (2.9%), and soft tissue infection (5.7%). There were no mortalities.

CONCLUSIONS

The article showcases an international collaborative effort that demonstrates the possibility of providing highly effective and safe surgical care for temporal lobe epilepsy even in low-resource environments. The authors hope that this model can be replicated in other areas with similar resource limitations.

Exoscope improves visualization and extent of hippocampal resection in temporal lobectomy

INTRODUCTION

Anterior temporal lobectomy (ATL) is a safe and well-validated procedure in the treatment of temporal lobe epilepsy (TLE), but is a challenging technique to master and still confers a risk of morbidity and mortality due to the complex anatomy of the mesial temporal lobe structures. Automated robotic 3D exoscopes have been developed to address limitations traditionally associated with microscopic visualization, allowing for ergonomic, high-definition 3D visualization with hands-free control of the robot. Given the potential advantages of using such a system for visualization of complex anatomy seen during mesial structure resection in ATL, this group sought to investigate impact on the percentage of hippocampal resection in both exoscope and microscope guided procedures.

METHODS

We conducted a retrospective analysis of 20 consecutive patients undergoing standard ATL for treatment of medically refractory TLE at our institution. Using pre-operative and post-operative imaging, the coronal plane cuts in which either the head, body, or tail of the hippocampus appeared were counted. The number of cuts in which the hippocampus appeared were multiplied by slice thickness to estimate hippocampal length.

RESULTS

Mean percentage of hippocampal resection was 61.1 (SD 13.1) and 76.5 (SD 6.5) for microscope and exoscope visualization, respectively (p = 0.0037).

CONCLUSION

Use of exoscope for mesial resection during ATL has provided good visualization for those in the operating room and the potential for a safe increase in hippocampal resection in our series. Further investigation of its applications should be evaluated to see if it will improve outcomes.

Right temporal lobe epilepsy surgery activates suppressed post-traumatic stress disorder 31 years after a robbery

Hippocampus and amygdala play central roles in the development of post-traumatic stress disorder (PTSD). Changes in neurological structures due to surgery leading to PTSD have previously been reported. In this case, we present a patient that develops PTSD right after epilepsy surgery in the right temporal lobe. The case adds knowledge to the mechanisms of storage of PTSD memories. A 56-year-old male suffering from refractory temporal lobe epilepsy was treated with an anteromesial temporal lobe resection on the right side. A few weeks after the surgery, he developed strong PTSD symptoms. They included flashbacks from a robbery he was subjected to three decades ago when he was 25 years old. In addition, he suffered from hypervigilance, irritability, and avoidance behavior. Psychotherapy eventually eased his symptoms. No previous disorders were recorded. No psychiatry symptoms were present before surgery. This case is one of few reports on the sudden occurrence of PTSD after epilepsy-surgery in the form of right-sided anteromesial temporal lobe resection. The disorder may not have been detected if not included in the Danish Epilepsy-Surgery-Protocol, among them both the pre-surgery psychiatric management and in the post-operative monitoring.

Surgery procedures in temporal lobe epilepsies

Temporal lobe epilepsy (TLE) is the most common cause of refractory epilepsy amenable for surgical treatment and seizure control. Surgery for TLE is a safe and effective strategy. The seizure-free rate after surgical resection in patients with mesial or neocortical TLE is about 70%. Resective surgery has an advantage over stereotactic radiosurgery in terms of seizure outcomes for mesial TLE patients. Both techniques have similar results for safety, cognitive outcomes, and associated costs. Stereotactic radiosurgery should therefore be seen as an alternative to open surgery for patients with contraindications for or with reluctance to undergo open surgery. Laser interstitial thermal therapy (LITT) has also shown promising results as a curative technique in mesial TLE but needs to be more deeply evaluated. Brain-responsive stimulation represents a palliative treatment option for patients with unilateral or bilateral MTLE who are not candidates for temporal lobectomy or who have failed a prior mesial temporal lobe resection. Overall, despite the expansion of innovative techniques in recent years, resective surgery remains the reference treatment for TLE and should be proposed as the first-line surgical modality. In the future, ultrasound therapies could become a credible therapeutic option for refractory TLE patients.

Focal to bilateral motor seizures in temporal lobe epilepsy during video-EEG monitoring: effects on surgical outcome

The aim of this study was to determine whether the occurrence of focal to bilateral motor seizures in the course of partial drug withdrawal during video-EEG monitoring (FTBMS-M) had a predictive value for seizure recurrence in surgically treated patients with mesial temporal lobe epilepsy (MTLE). We analyzed the outcomes of 59 patients who underwent temporal lobe resection at 12 month postoperative follow up. In total, 48 out of 59 patients were rendered seizure free (81.4%). We analyzed seizure recurrence after surgery with reference to: (i) occurrence of seizures after partial drug withdrawal during video-EEG monitoring (FTBMS-M); (ii) history of secondarily generalized seizures during antiepileptic drug treatment prior to presurgical evaluation (FTBMS-H) and (iii) other possible confounding factors (sex, age, epilepsy duration, side of surgery, presence of hippocampal sclerosis, and history of febrile seizures). We found no differences in the frequency of seizure recurrences between patients with FTBMS-M and patients without FTBMS-M (4/20 vs. 7/39; p = 0.848). Conversely, the frequency of seizure recurrence was significantly higher among the patients with FTBMS-H than among the patients without FTBMS-H (7/20 vs. 4/39; p = 0.021). The predictive value of FTBMS-H for postoperative seizure recurrence was confirmed in logistic regression analysis. We found a statistically significant influence of FTBMS-H on poor outcome after surgery, but not of FTBMS-M or other confounding variables, which suggests that withdrawal seizures do not affect postsurgical seizure control.

The importance of preoperative planning to perform safely temporal lobe surgery

Neurosurgeons should know the anatomy required for safe temporal lobe surgery approaches. The present study aimed to determine the angles and distances necessary to reach the temporal stem and temporal horn in surgical approaches for safe temporal lobe surgery by using a 3.0 T magnetic resonance imaging technique in post-mortem human brain hemispheres fixed by the Klingler method. In our study, 10 post-mortem human brain hemisphere specimens were fixed according to the Klingler method. Magnetic resonance images were obtained using a 3.0 T magnetic resonance imaging scanner after fixation. Surgical measurements were conducted for the temporal stem and temporal horn by magnetic resonance imaging, and dissection was then performed under a surgical microscope for the temporal stem. Each stage of dissection was achieved in high-quality three-dimensional images. The angles and distances to reach the temporal stem and temporal horn were measured in transcortical T1, trans-sulcal T1-2, transcortical T2, trans-sulcal T2-3, transcortical T3, and subtemporal trans-collateral sulcus approaches. The safe maximum posterior entry point for anterior temporal lobectomy was measured as 47.16 ± 5.00 mm. Major white-matter fibers in this region and their relations with each other are shown. The distances to the temporal stem and temporal horn, which are important in temporal lobe surgical interventions, were measured radiologically, and safe borders were determined. Surgical strategy and preoperative planning should consider the relationship of the lesion and white-matter pathways.

New Horizons in Temporal Lobe Seizure Control

SUMMARY

In patients with mesial temporal lobe epilepsy, high-frequency, low-amplitude electrical stimulation (ES) was applied during 3 weeks through contacts of intracranial electrodes that defined the epileptogenic zone. This subacute ES induced cessation of spontaneous seizures, decreased the number of EEG interictal spikes, caused a 10-fold increase in threshold to induce postdischarges, and showed a profound decrease in regional blood flow of the stimulated area in SPECT studies. Autoradiography analysis of surgical specimens from these patients demonstrated increased expression of benzodiazepine receptors and in gamma-aminobutyric acid content, particularly in the parahippocampal cortex. These observations provided evidence of a gamma-aminobutyric acid-mediated antiepileptic effect induced by ES. Several reports of long-term hippocampal ES through internalized neurostimulators have confirmed the antiepileptic effect on mesial temporal lobe-initiated seizures, with preservation of neuropsychological performance, in particular memory functions. The experience of the authors is that the response is optimal in patients without hippocampal sclerosis evidenced by MRI, whereas it is less significant and delayed in patients with hippocampal sclerosis. Other studies reported the best result stimulating through the contacts in the subiculum, the transition between the hippocampus and parahippocampal cortex, that usually escapes to the hippocampal sclerosis. Currently, the effect of ES directed at the subiculum and the parahippocampal cortex in patients with hippocampal sclerosis is under investigation.

[Invasive EEG for temporal lobe epilepsy: selection of technique]

BACKGROUND

Non-invasive EEG reveals epileptogenic zone in 70% of patients. In other cases, invasive EEG monitoring is indicated. Various implantation strategies and techniques of intracranial EEG (icEEG) potentially provide different outcomes. Choosing the optimal icEEG technique may be challenging.

OBJECTIVE

To analyze the results of icEEG in adults with temporal lobe epilepsy and to determine the algorithm for selection of optimal invasive EEG technique.

MATERIAL AND METHODS

The study included 82 patients with temporal lobe epilepsy who underwent invasive EEG. Effectiveness of invasive EEG was determined by detection of epileptogenic zone and post-resection outcomes. Postoperative results were analyzed throughout more than 6-month follow-up period using the Engel grading system. Statistical analysis was conducted using the Fisher's exact test.

RESULTS

Epileptogenic zone was revealed in 72 (88%) cases. Invasive EEG was supplemented by another modality in 3 (4%) patients. Mean follow-up period after resection was 17 months in 45 patients. Favorable outcomes were achieved in 31 (69%) cases. Statistical analysis showed that identification of epileptogenic zone depends existing of lesion and symptoms of seizures. Selection algorithm for optimal technique of invasive EEG was determined considering own results and literature data.

CONCLUSION

Invasive EEG results and post-resection outcomes demonstrated favorable efficacy of original algorithm. The last one may be used in decision-making on optimal technique of invasive EEG in adults with temporal lobe epilepsy.

Experience From 211 Transcortical Selective Amygdalohippocampectomy Procedures: Relevant Surgical Anatomy and Review of the Literature

BACKGROUND

Selective amygdalohippocampectomy (SelAH) is designed to treat medically refractory mesial temporal lobe epilepsy with reduced morbidity compared to standard anterior temporal lobectomy. At our institution, we perform SelAH via a transcortical approach via small corticectomy in the middle temporal gyrus.

OBJECTIVE

To discuss the surgical anatomy and nuances of SelAH, share our institutional experience, and perform a review of literature.

METHODS

Institutional experience was recorded by collecting demographic and outcome data from 1999 to 2017 under an Institutional Review Board protocol in a prospective manner using a REDCap database.

RESULTS

A total of 211 SelAH procedures were performed at our institution between 1999 and 2017. Of these patients, 54% (113/211) were females. The average age at surgery was 39.4 yr. Two-year Engel outcome data were available for 168 patients, of which 73% (123/168) had Engel I outcomes. Engel II outcomes were reported in 16.6% (28/168), III in 4.7% (8/168), and IV in 5.3% (9/168). Our review of literature showed that this is comparable to the seizure freedom rates reported by other groups. We then reviewed our surgical methodology based on operative reports and created illustrations of the surgical anatomy of temporal lobe approach. These illustrations were compared with postoperative magnetic resonance imaging to provide a better 3D understanding of the complex architecture of mesial temporal structures.

CONCLUSION

SelAH is a minimally invasive, safe, and effective approach for the treatment of medically refractory epilepsy with good surgical outcomes and low morbidity. We feel that mastering the complex anatomy of this approach helps achieve successful outcomes.

Stereoelectroencephalography versus Subdural Electrode Implantation to Determine Whether Patients with Drug-resistant Epilepsy Are Candidates for Epilepsy Surgery

Epilepsy is a chronic condition that affects about 50 million individuals worldwide. While its challenges are profound, there are increasing instances where antiepileptic drugs (AEDs) fail to provide relief to epileptic manifestations. For these pharmacoresistant cases, epilepsy surgery often is an effective route for treatment. However, the complexity and challenges associated with presurgical evaluations have prevented more widespread utilization of epilepsy surgery in pharmacoresistant cases. While preliminary work-ups and non-invasive diagnostic imaging have allowed for limited identification of the epileptogenic zone (EZ), there is yet to be an established pre-determined algorithm for surgical evaluation of patients with epilepsy. However, two modalities are currently being used for localization of the EZ and in determining candidates for surgery: stereoelectroencephalography (SEEG) and subdural electrodes (SDEs). SDE has been used in the United States for decades; however, SEEG now provides a less invasive option for mapping brain regions. We seek to address which intracranial monitoring technique is superior. Through a review of the outcomes of various clinical studies, SEEG was found to have greater safety and efficiency benefits than SDE, such as lower morbidity rates, lower prevalence of neurological deficits, and shorter recovery times. Moreover, SEEG was also found to have further functional benefits by allowing for deeper targeting of cerebral tissue along with bilateral hemispheric monitoring. This has led to increased rates of seizure freedom and control among SEEG patients. Nevertheless, further studies on the limitations and advancements of SEEG and SDE are still required to provide a more comprehensive understanding regarding their application.

Comparison of minimally invasive and traditional surgical approaches for refractory mesial temporal lobe epilepsy: A systematic review and meta-analysis of outcomes

Magnetic resonance-guided laser interstitial laser therapy (MRgLITT) and radiofrequency ablation (RFA) represent two minimally invasive methods for the treatment of drug-refractory mesial temporal lobe epilepsy (mTLE). We performed a systematic review and a meta-analysis to compare outcomes and complications between MRgLITT, RFA, and conventional surgical approaches to the temporal lobe (i.e., anterior temporal lobe resection [ATL] or selective amygdalohippocampectomy [sAHE]). Forty-three studies (13 MRgLITT, 6 RFA, and 24 surgery studies) involved 554, 123, 1504, and 1326 patients treated by MRgLITT, RFA, ATL, or sAHE, respectively. Engel Class I (Engel-I) outcomes were achieved after MRgLITT in 57% (315/554, range = 33.3%-67.4%), RFA in 44% (54/123, range = 0%-67.2%), ATL in 69% (1032/1504, range = 40%-92.9%), and sAHE in 66% (887/1326, range = 21.4%-93.3%). Meta-analysis revealed no significant difference in seizure outcome between MRgLITT and RFA (Q = 2.74, p = .098), whereas ATL and sAHE were both superior to MRgLITT (ATL: Q = 8.92, p = .002; sAHE: Q = 4.33, p = .037) and RFA (ATL: Q = 6.42, p = .0113; sAHE: Q = 5.04, p = .0247), with better outcome in patients at follow-up of 60 months or more. Mesial hippocampal sclerosis (mTLE + hippocampal sclerosis) was associated with significantly better outcome after MRgLITT (Engel-I outcome in 64%; Q = 8.55, p = .0035). The rate of major complications was 3.8% for MRgLITT, 3.7% for RFA, 10.9% for ATL, and 7.4% for sAHE; the differences did not show statistical significance. Neuropsychological deficits occurred after all procedures, with left-sided surgeries having a higher rate of verbal memory impairment. Lateral functions such as naming or object recognition may be more preserved in MRgLITT. Thermal therapies are effective techniques but show a significantly lower rate of Engel-I outcome in comparison to ATL and sAHE. Between MRgLITT and RFA there were no significant differences in Engel-I outcome, whereby the success of treatment seems to depend on the approach used (e.g., occipital approach). MRgLITT shows a similar rate of complications compared to RFA, whereas patients undergoing MRgLITT may experience fewer major complications compared to ATL or sAHE and might have a more beneficial neuropsychological outcome.

Robot Assisted MRI-Guided LITT of the Anterior, Lateral, and Medial Temporal Lobe for Temporal Lobe Epilepsy

Robotic systems have fundamentally altered the landscape of functional neurosurgery. These allow automated stereotaxy with high accuracy and reliability, and are rapidly becoming a mainstay in stereotactic surgeries such as deep brain stimulation (DBS), stereoelectroencephalography (SEEG), and stereotactic laser ablation/MRI guided laser interstitial thermal therapy (MRgLITT). Robotic systems have been effectively applied to create a minimally invasive approach for diagnostics and therapeutics in the treatment of epilepsy, utilizing robots for expeditious and accurate stereotaxy for SEEG and MRgLITT. MRgLITT has been shown to approach open surgical techniques in efficacy of seizure control while minimizing collateral injury. We describe the use of robot assisted MRgLITT for a minimally invasive laser anterior temporal lobotomy, describing the approach and potential pitfalls. Goals of MRgLITT are complete ablation of the epileptogenic zone and avoiding injury to uninvolved structures. In the middle fossa these include structures such as cranial nerves in the skull base and cavernous sinus and the thalamus. These can be mitigated with careful trajectory planning and control of laser ablation intensity.

Focal-to-bilateral motor seizures in temporal lobe epilepsy during video-EEG monitoring: effects on surgical outcome

The aim of this study was to determine whether the occurrence of focal-to-bilateral motor seizures in the course of partial drug withdrawal during video-EEG monitoring (FTBMS-M) had a predictive value for seizure recurrence in surgically treated patients with mesial temporal lobe epilepsy (MTLE). We analyzed the outcomes of 59 patients who underwent temporal lobe resection and had postoperative follow-up from 6 to 58 months. In total, 48 out of 59 patients were rendered seizure free (81.4%). We analyzed seizure recurrence after surgery with reference to: (i) occurrence of seizures after partial drug withdrawal during video-EEG monitoring (FTBMS-M); (ii) history of secondarily generalized seizures during antiepileptic drug treatment prior to presurgical evaluation (FTBMS-H) and (iii) other possible confounding factors (sex, age, epilepsy duration, side of surgery, presence of hippocampal sclerosis, and history of febrile seizures). We found no differences in the frequency of seizure recurrences between patients with FTBMS-M and patients without FTBMS-M (4/20 vs. 7/39; p = 0.848). Conversely, the frequency of seizure recurrence was significantly higher among the patients with FTBMS-H than among the patients without FTBMS-H (7/20 vs. 4/39; p = 0.021). The predictive value of FTBMS-H for postoperative seizure recurrence was confirmed in logistic regression analysis. We found a statistically significant influence of FTBMS-H on poor outcome after surgery, but not of FTBMS-M or other confounding variables, which suggests that withdrawal seizures do not affect post-surgical seizure control.

Temporal lobe structural evaluation after transsylvian selective amygdalohippocampectomy

OBJECTIVE

Mesial temporal lobe epilepsy (MTLE) is the most common type of focal epilepsy in adolescents and adults, and in 65% of cases, it is related to hippocampal sclerosis (HS). Selective surgical approaches to the treatment of MTLE have as their main goal resection of the amygdala and hippocampus with minimal damage to the neocortex, temporal stem, and optic radiations (ORs). The object of this study was to evaluate late postoperative imaging findings on the temporal lobe from a structural point of view.

METHODS

The authors conducted a retrospective evaluation of all patients with refractory MTLE who had undergone transsylvian selective amygdalohippocampectomy (SAH) in the period from 2002 to 2015. A surgical group was compared to a control group (i.e., adults with refractory MTLE with an indication for surgical treatment of epilepsy but who did not undergo the surgical procedure). The inferior frontooccipital fasciculus (IFOF), uncinate fasciculus (UF), and ORs were evaluated on diffusion tensor imaging analysis. The temporal pole neocortex was evaluated using T2 relaxometry.

RESULTS

For the IFOF and UF, there was a decrease in anisotropy, voxels, and fibers in the surgical group compared with those in the control group (p < 0.001). An increase in relaxometry time in the surgical group compared to that in the control group (p < 0.001) was documented, suggesting gliosis and neuronal loss in the temporal pole.

CONCLUSIONS

SAH techniques do not seem to totally preserve the temporal stem or even spare the neocortex of the temporal pole. Therefore, although the transsylvian approaches have been considered to be anatomically selective, there is evidence that the temporal pole neocortex suffers structural damage and potentially functional damage with these approaches.

Selective posterior cerebral artery amobarbital test: a predictor of memory following subtemporal selective amygdalohippocampectomy

BACKGROUND

The selective posterior cerebral artery (PCA) amobarbital test, or PCA Wada test, is used to predict memory impairment after epilepsy surgery in patients who have previously had a failed internal carotid artery (ICA) amobarbital test.

METHODS

Medical records from 2012 to 2018 were retrospectively reviewed for all patients with seizures who underwent a selective PCA Wada test at our institution following a failed or inconclusive ICA Wada test. Standardized neuropsychological testing was performed before and during the Wada procedure and postoperatively in patients who underwent resection.

RESULTS

Thirty-three patients underwent a selective PCA Wada test, with no complications. Twenty-six patients with medically refractory epilepsy had a seizure focus amenable to selective amygdalohippocampectomy (AHE). Six patients (23%, n=26) had a failed PCA Wada test and did not undergo selective AHE, seven (27%) declined surgical resection, leaving 13 patients who underwent subtemporal selective AHE. Hippocampal sclerosis was found in all 13 patients (100%). Twelve patients (92%) subsequently underwent formal neuropsychological testing and all were found to have stable memory. Ten patients (77%) were seizure-free (Engel Class I), with average follow-up of 13 months.

CONCLUSION

The selective PCA Wada test is predictive of memory outcomes after subtemporal selective AHE in patients with a failed or inconclusive ICA Wada test. Furthermore, given the low risk of complications and potential benefit of seizure freedom, a selective PCA Wada test may be warranted in patients with medically intractable epilepsy who are candidates for a selective AHE and who have a prior failed or inconclusive ICA Wada test.

Systematic review and network meta-analysis of resective surgery for mesial temporal lobe epilepsy

OBJECTIVE

To evaluate the effectiveness of anterior temporal lobectomy (ATL) versus selective amygdalohippocampectomy (SAH) on seizure-free outcome in patients with temporal lobe epilepsy, using both direct and indirect evidence from the literature.

METHODS

MEDLINE, Embase and Cochrane databases were searched for original research articles and systematic reviews comparing ATL versus SAH, and ATL or SAH versus medical management (MM). The outcome was seizure freedom at 12 months of follow-up or longer. Direct pairwise meta-analyses were conducted, followed by a random-effect Bayesian network meta-analysis (NMA) combining direct and indirect evidence.

RESULTS

Twenty-eight articles were included (18 compared ATL vs SAH, 1 compared ATL vs SAH vs MM, 8 compared ATL vs MM, and 1 compared SAH vs MM). Direct pairwise meta-analyses showed no significant differences in seizure-free outcome of ATL versus SAH (OR 1.14, 95% CI 0.93 to 1.39; p=0.201), but the odds of seizure-free outcome were higher for ATL versus MM (OR 29.16, 95% CI 10.44 to 81.50; p<0.00001), and SAH versus MM (OR 28.42, 95% CI 10.17 to 79.39; p<0.00001). NMA also showed that the odds of seizure-free outcome were no different in ATL versus SAH (OR 1.15, 95% credible interval (CrI) 0.84-1.15), but higher for ATL versus MM (OR 27.22, 95% CrI 15.38-27.22), and SAH versus MM (OR 23.57, 95% CrI 12.67-23.57). There were no significant differences between direct and indirect comparisons (all p>0.05).

CONCLUSION

Direct evidence, indirect evidence and NMA did not identify a difference in seizure-free outcome of ATL versus SAH.

Surgical and neurological complications in temporal lobe epilepsy surgery in modern era

Background

Temporal lobe epilepsy is the most common form of focal epilepsy, and surgical treatment has been proven to be an effective and safe management. Despite its safety, it is important to know that some complications and/or even death can be seen after surgery. Neurosurgeons should be able to precisely inform epilepsy surgery candidates about the possible unwanted/unexpected conditions after surgery.

Methods

Fifty-three patients who underwent anterior temporal lobe resection due to temporal lobe epilepsy by a single surgeon were investigated retrospectively regarding postoperative surgical and neurological complications.

Results

Overall complication rate was found to be 19%, surgical complications comprised 13.2% whereas neurological complications were 5.8%. Three patients underwent a second surgery whereas the rest had medical treatment or recovered spontaneously. Fortunately persistent complication rate was found to be 0%, and there was no mortality.

Conclusions

Anterior temporal lobe resection is a safe and very effective surgical modality for the treatment of temporal lobe epilepsy. However, unexpected complications may be possible in this modern era and a surgeon should trust in him/herself not in modern equipments.

[Seizure outcome after surgery for medically intractable mesial temporal lobe epilepsy and its predictors]

OBJECTIVE

To evaluate seizure outcome in patients receiving surgery for chronic medically intractable mesial temporal lobe epilepsy (MTLE) and analyze its possible predictors.

METHODS

This retrospective study was conducted in patients with chronic medically intractable MTLE undergoing anterior temporal lobectomy (ATL) or selective amygdalohippocampectomy (SAH) in our department between September, 2011 and October, 2013. The patients were followed up for 3.5 to 5.5 years, during which the seizure outcome was evaluated according to Engel's classification. The clinical data were collected from the patients to identify the possible predictors that affected the outcome of the patients using Mann-Whitney U test or Kruskal-Wallis test.

RESULTS

Atotal of 34 patients were included in this study with a definite diagnosis of chronic medically intractable MTLE after preoperative noninvasive and invasive evaluation. In 4 of these patients, invasive EEG monitoring confirmed that epileptic discharges originated from the bilateral mesial temporal lobe, and hence surgical resection of the epileptogenic zone was not performed. The other 30 patients underwent surgical resection of the epileptogenic zone with ALT or SAH, and favorable outcomes were achieved in 23 (76.7%) of the patients. Of the 7 (23.3%) patients with poor outcomes, 6 patients presented with typical automatism and aura with frequent secondary generalized tonic-clonic seizure, and the other one patient exhibited impaired intelligence. Statistical analysis suggested that the patients without a special disease history (trauma, febrile seizure, or encephalitis) tended to have a more favorable seizure outcome.

CONCLUSIONS

Surgical interventions can achieve good therapeutic effect on chronic medically intractable MTLE, and patients without a special disease history may have more favorable outcomes after the surgery. SAH via the superior temporal sulcus approach can be a better surgical option for intractable MTLE.

Surgical treatment for refractory epilepsy

The goal of any epilepsy surgery is to improve patient's quality of life by achieving seizure freedom or by reducing the frequency of severely debilitating seizures. To achieve this goal, non-invasive and invasive diagnostic methods must precisely delineate the epileptogenic zone (EZ), which is defined as the area that needs to be resected to obtain seizure freedom. At the same time, the correct identification of eloquent brain areas is inevitable to avoid new neurological deficits from surgery. In recent years, the technical advances in diagnostics have enabled us to achieve these goals in an increasing number of cases. As a consequence, and with new surgical treatment options available, the number of patients who might benefit from epilepsy surgery is constantly increasing. Especially in pediatric epilepsy, early surgical intervention is becoming frequently advocated as it has been shown to improve cognitive and behavioral outcome. Specialized epilepsy centers and multidisciplinary teams are required to provide adequate care and treatment. The goal of this review is to describe important diseases that are accessible to epilepsy surgery and to give an overview of current diagnostic methods. The focus lies on established as well as novel techniques in epilepsy surgery. The presurgical work-up and patient selection is outlined.

Diagnosis and Surgical Treatment of Drug-Resistant Epilepsy

Despite appropriate trials of at least two antiepileptic drugs, about a third of patients with epilepsy remain drug resistant (intractable; refractory). Epilepsy surgery offers a potential cure or significant improvement to those with focal onset drug-resistant seizures. Unfortunately, epilepsy surgery is still underutilized which might be in part because of the complexity of presurgical evaluation. This process includes classifying the seizure type, lateralizing and localizing the seizure onset focus (epileptogenic zone), confirming the safety of the prospective brain surgery in terms of potential neurocognitive deficits (language and memory functions), before devising a surgical plan. Each one of the above steps requires special tests. In this paper, we have reviewed the process of presurgical evaluation in patients with drug-resistant focal onset epilepsy.

Surgical Considerations of Intractable Mesial Temporal Lobe Epilepsy

Surgery of temporal lobe epilepsy is the best opportunity for seizure freedom in medically intractable patients. The surgical approach has evolved to recognize the paramount importance of the mesial temporal structures in the majority of patients with temporal lobe epilepsy who have a seizure origin in the mesial temporal structures. For those individuals with medically intractable mesial temporal lobe epilepsy, a selective amygdalohippocampectomy surgery can be done that provides an excellent opportunity for seizure freedom and limits the resection to temporal lobe structures primarily involved in seizure genesis.

Intraoperative hippocampal electrocorticography frequently captures electrographic seizures and correlates with hippocampal pathology

OBJECTIVE

Relationship between electrographic seizures on hippocampal electrocorticography (IH-ECoG) and presence/type of hippocampal pathology remains unclear.

METHODS

IH-ECoG was recorded for 10-20 min from the ventricular surface of the hippocampus following removal of the temporal neocortex in 40 consecutive patients. Correlation between intraoperative hippocampal seizures and preoperative MRI, hippocampal histopathology, and EEG from invasive monitoring was determined.

RESULTS

IH-ECoG captured electrographic seizures in 15/40 patients (in 8/23 with abnormal hippocampal signal on MRI and 7/17 patients without MRI abnormality). Hippocampal neuronal loss was observed in 22/40 (Group 1), while 18/40 had no significant neuronal loss (Group 2). In Group 1, 4/22 had seizures on IH-ECoG, while 11/18 had electrographic seizures in Group 2. In 24/40 patients who underwent prolonged extraoperative intracranial EEG (IC-EEG) recording, hippocampal seizures were captured in 14. Of these, 7 also had seizures during IH-ECoG. In 10/24 IC-EEG patients without seizures, 3 had seizures on IH-ECoG.

CONCLUSIONS

IH-ECoG frequently captures spontaneous electrographic seizures. These are more likely to occur in patients with pathologic processes that do not disrupt/infiltrate hippocampus compared to patients with intractable epilepsy associated with disrupted hippocampal architecture.

SIGNIFICANCE

Intraoperative hippocampal seizures may result from deafferentation from the temporal neocortex and disinhibition of the perforant pathway.

A classification system for verifying the long-term efficacy of resective surgery for drug-resistant seizures

OBJECTIVE

To verify the long-term efficacy of resective surgery, we created a classification system in which strictly defined patterns of postoperative seizure emergence are incorporated as basic components and the seizure states throughout the entire follow-up period are assessed comprehensively.

METHODS

In our system, Class I has three subclasses (A-C); subclasses A and B are identical to Engel I-A and I-B, respectively. Subclass C comprises patients whose disabling seizures remit within the first 2 years postoperatively. Patients in Class II have only 1-3 days with disabling seizures throughout follow-up after the first 2 years. Patients in Class III have a maximum of 3 seizure days annually, and those in Class IV have ≥4 seizure days annually after the first 2 years. Classes II-IV each have 2 subclasses (A and B): subclass A, late recurrence (i.e., the first seizure occurs after 2 years postoperatively); and subclass B, early recurrence (i.e., first seizure within 2 years). In 646 patients who underwent resective surgery (temporal lobe resection, 74.6%) and were followed for at least 8 years (mean, 14.6 years), we analyzed three patterns of postoperative seizures: early remission, late recurrence, and occasional seizures. In addition, we investigated the differences between the long-term seizure outcomes of the cohort as determined according to our system and the Engel scale.

RESULTS

Overall, 52.9% of the cohort experienced at least one disabling seizure postoperatively throughout the follow-up period; in 1/3 of these patients, the first seizure occurred after 2 years. In 73.8% of the 80 patients who manifested the running-down phenomenon, seizure remission occurred within the first 2 years. In addition, 36.7% of the 283 patients who had disabling seizures after 2 years experienced only 1-3 seizure days. Engel Class I-C included about 30% of the patients who had ≥4 seizure days after 2 years. The long-term seizure outcomes, determined according to our system, were: Class I, 56.2% (C, 9.1%) of the overall cohort; Class II, 16.1% (A, 11.0%); and Class III/IV, 27.7% (A, 6.6%).

CONCLUSION

Our system clarifies the actual effect of resective surgery more precisely than the Engel scale and thus may be useful for comparing outcomes between different surgical procedures or for identifying potential risk factors predicting unfavorable outcome.

Does early postoperative drug regimen impact seizure control in patients undergoing temporal lobe resections?

OBJECTIVE

To evaluate the impact of postoperative antiepileptic drug (AED) load on seizure control in patients who underwent surgical treatment for pharmacoresistant mesiotemporal lobe epilepsy during the first two postoperative years.

PATIENTS AND METHODS

532 consecutive patients (48.7% males and 51.7% females) who underwent surgical treatment for mesiotemporal lobe epilepsy were retrospectively evaluated regarding effects of AED load on seizures control during the first 2 years following epilepsy surgery. We analyzed whether postoperative increases in postoperative AED load are associated with better seizure control in patients initially not seizure free, and if postoperative decreases in postoperative AED load would increase the risk for seizure persistence or recurrence. For statistical analyses, Fisher's exact and Wilcoxon test were applied.

RESULTS

68.9, 64.0 and 59.1% of patients were completely seizure free (Engel Ia) at 3, 12 and 24 months after surgery, respectively. Patients in whom daily drug doses were increased did not have a higher rate of seizure freedom at any of the three follow-up periods. Of 16 patients achieving secondary seizure control at 12 months after surgery, only one did so with an increase in drug load in contrast to 15 patients who experienced a running down of seizures independent of drug load increases. Decreases in drug load did not significantly increase the risk for seizure recurrence. Of postoperatively seizure free patients at 3 months after surgery in whom AED were consequently reduced, 85% remained completely seizure free at 1 year and 76% at 1 year after surgery, respectively, as opposed to 86% each when AED was not reduced (differences n.s.). Mean daily drug load was significantly lower in seizure free patients at 12 and 24 months compared to patients with ongoing seizures.

CONCLUSION

In this large patient cohort stratified to the epilepsy syndrome neither did a postoperative reduction in drug load significantly increase the risk for seizure relapse nor did increases in drug dosages lead to improved seizure control. Mean drug load was on average lower in seizure free- than non-seizure free patients at 12 and 24 months of follow-up. Secondary seizure control after initial postoperative seizures in > 90% of cases occurred as a running down, independent of an AED increase. Thus, the effect of the surgical intervention rather than the postoperative drug regimen was the key determinant for seizure control. This finding supports a curative role of temporal lobe surgery rather than an effect rendering the majority of patients' pharmacoresponsive with a critical role of the antiepileptic drug regime for seizure control.

Transtemporal amygdalohippocampectomy: a novel minimally-invasive technique with optimal clinical results and low cost

Mesial temporal sclerosis creates a focal epileptic syndrome that usually requires surgical resection of mesial temporal structures.

OBJECTIVE

To describe a novel operative technique for treatment of temporal lobe epilepsy and its clinical results.

METHODS

Prospective case-series at a single institution, performed by a single surgeon, from 2006 to 2012. A total of 120 patients were submitted to minimally-invasive keyhole transtemporal amygdalohippocampectomy.

RESULTS

Of the patients, 55% were male, and 85% had a right-sided disease. The first 70 surgeries had a mean surgical time of 2.51 hours, and the last 50 surgeries had a mean surgical time of 1.62 hours. There was 3.3% morbidity, and 5% mild temporal muscle atrophy. There was no visual field impairment. On the Engel Outcome Scale at the two-year follow-up, 71% of the patients were Class I, 21% were Class II, and 6% were Class III.

CONCLUSION

This novel technique is feasible and reproducible, with optimal clinical results.

Role of the temporal pole in temporal lobe epilepsy seizure networks: an intracranial electrode investigation

OBJECTIVE A convergence of clinical research suggests that the temporal pole (TP) plays an important and potentially underappreciated role in the genesis and propagation of seizures in temporal lobe epilepsy (TLE). Understanding its role is becoming increasingly important because selective resections for medically intractable TLE spare temporopolar cortex (TPC). The purpose of this study was to characterize the role of the TPC in TLE after using dense electrocorticography (ECoG) recordings in patients undergoing invasive monitoring for medically intractable TLE. METHODS Chronic ECoG recordings were obtained in 10 consecutive patients by using an array customized to provide dense coverage of the TP as part of invasive monitoring to localize the epileptogenic zone. All patients would eventually undergo cortico-amygdalohippocampectomy. A retrospective review of the patient clinical records including ECoG recordings, neuroimaging studies, neuropathology reports, and clinical outcomes was performed. RESULTS In 7 patients (70%), the TP was involved at seizure onset; in 7 patients (70%), there were interictal discharges from the TP; and in 1 case, there was early spread to the TP. Seizure onset in the TP did not necessarily correlate with preoperative neuroimaging abnormalities of the TP. CONCLUSIONS These data demonstrate that TPC commonly plays a crucial role in temporal lobe seizure networks. Seizure onset from the TP would not have been predicted based on available neuroimaging data or interictal discharges. These findings illustrate the importance of thoroughly considering the role of the TP prior to resective surgery for TLE, particularly when selective mesial resection is being considered.

Mesial temporal lobe epilepsy: long-term seizure outcome of patients primarily treated with transsylvian selective amygdalohippocampectomy

OBJECTIVE The aim of this study was to present long-term seizure outcome data in a consecutive series of patients with refractory mesial temporal lobe epilepsy primarily treated with transsylvian selective amygdalohippocampectomy (SAHE). METHODS The authors retrospectively analyzed prospectively collected data for all patients who had undergone resective surgery for medically refractory epilepsy at their institution between July 1994 and December 2014. Seizure outcome was assessed according to the International League Against Epilepsy (ILAE) and the Engel classifications. RESULTS The authors performed an SAHE in 158 patients (78 males, 80 females; 73 right side, 85 left side) with a mean age of 37.1 ± 10.0 years at surgery. Four patients lost to follow-up and 1 patient who committed suicide were excluded from analysis. The mean follow-up period was 9.7 years. At the last available follow-up (or before reoperation), 68 patients (44.4%) had achieved an outcome classified as ILAE Class 1a, 46 patients (30.1%) Class 1, 6 patients (3.9%) Class 2, 16 patients (10.4%) Class 3, 15 patients (9.8%) Class 4, and 2 patients (1.3%) Class 5. These outcomes correspond to Engel Class I in 78.4% of the patients, Engel Class II in 10.5%, Engel Class III in 8.5%, and Engel Class IV in 2.0%. Eleven patients underwent a second surgery (anterior temporal lobectomy) after a mean of 4.4 years from the SAHE (left side in 6 patients, right side in 5). Eight (72.7%) of these 11 patients achieved seizure freedom. The overall ILEA seizure outcome since (re)operation after a mean follow-up of 10.0 years was Class 1a in 72 patients (47.0%), Class 1 in 50 patients (32.6%), Class 2 in 7 patients (4.6%), Class 3 in 15 patients (9.8%), Class 4 in 8 patients (5.2%), and Class 5 in 1 patient (0.6%). These outcomes correspond to an Engel Class I outcome in 84.3% of the patients. CONCLUSIONS A satisfactory long-term seizure outcome following transsylvian SAHE was demonstrated in a selected group of patients with refractory temporal lobe epilepsy.

Prognostic significance of postoperative spikes varied in different surgical procedures for mesial temporal sclerosis

PURPOSE

We conducted this study to compare the occurrence and prognostic significance of early postoperative interictal epileptiform discharges (IEDs) on seizure outcomes between corticoamygdalohippocampectomy (CAH) and selective amygdalohippocampectomy (SAH).

METHODS

We reviewed our database of patients who had epilepsy surgery with hippocampus atrophy or signal changes on brain MRIs and pathology of mesial temporal sclerosis. One hundred and seventy-seven CAH and 39 SAH patients were enrolled. Postoperative EEG within 30days, other preoperative variables and seizure outcome 2years after surgery were obtained for analysis. Engel's IA and IB were defined as seizure-free.

RESULTS

There was no significant difference in the seizure-free rate between the two procedures (127 (71.8%) of CAH vs 30 (76.9%) of SAH, p=0.51). Postoperative IEDs were more frequently seen in the SAH group (64.1%) than in the CAH group (29.9%), p<0.001. The IEDs in the SAH group did not show correlation with the seizure outcome 2 years after surgery. In the CAH group, patients who had no postoperative IEDs showed a higher seizure-free rate compared to those with IEDs (78.2% vs 56.6%, p=0.003; OR 2.267, 95% CI 1.09-4.73, p=0.029 in multivariate logistic regression).

CONCLUSIONS

Early postoperative IEDs are more frequently seen in SAH than in CAH. Unlike in patients with CAH, the presence of IEDs after SAH was not a predictor of seizure recurrence. The type of surgery should be considered while utilizing postoperative IEDs for evaluating the prognosis.

Usefulness of StereoEEG-based tailored surgery for medial temporal lobe epilepsy. Preliminary results in 11 patients

OBJECTIVE

Surgical options for medial temporal lobe epilepsy (MTLE) include anterior temporal lobectomy (ATL) and selective amygdalohippocampectomy (SAH). Optimal criteria for choosing the appropriate surgical approach remain uncertain. This article reports 11 consecutive cases in which electrophysiological findings of stereoelectroencephalography (SEEG) were used to determine the optimal surgical approach.

PATIENTS AND METHODS

Eleven consecutive patients with MTLE underwent SEEG evaluation and were placed in either the medial or the medial+lateral group based on the findings. Patients in the medial group underwent SAH using the subtemporal approach, and patients in the medial+lateral group underwent SEEG-guided anterior temporal lobectomy. SEEG findings were also compared with other examinations including flumazenil (FMZ)-positron emission tomography (PET), fluorine-18 labeled fluorodeoxyglucose (FDG)-PET, and magnetoencephalography (MEG). Results were evaluated to determine which examinations most consistently identified the epileptogenic zone.

RESULTS

Of the 11 cases, 4 patients were placed in the medial group, and 7 patients in the medial+lateral group. Of patients, 90.9% were classified in class I of the Engel Epilepsy Surgery Outcome Scale, while 72.7% were classified in class I by the International League Against Epilepsy (ILAE) system. Analyzed by group, 100% of the medial group experienced an Engel class I outcome in the medial group, compared to 85.7% in the medial+lateral group. SEEG findings were comparable with FDG-PET results (10 of 11, 91%).

CONCLUSION

Tailored surgery guided by SEEG is an electrophysiologically feasible treatment for MTLE that can result in favorable outcomes. Although seizures are thought to originate in the medial temporal lobe in MTLE, it is important for involvement of the lateral temporal cortex to be also considered in some cases.

Pediatric Epilepsy: Neurology, Functional Imaging, and Neurosurgery

In this chapter we provide a comprehensive review of the current role that functional imaging can have in the care of the pediatric epilepsy patient from the perspective of the epilepsy neurologist and the epilepsy neurosurgeon. In the neurology section, the diagnosis and classification of epilepsy adapted by the International League Against Epilepsy as well as the etiology and incidence of the disease is presented. The neuroimaging section describes how advanced nuclear medicine imaging methods can be synergized to provide a maximum opportunity to localize an epileptogenic focus. This section described the value of FDG-PET and regional cerebral blood flow SPECT in the identification of an epileptogenic focus. The imaging section also emphasizes the importance on developing a dedicated epilepsy management team, comprised of an epilepsy imaging specialist, epilepsy neurologist and epilepsy neurosurgeon, to provide the maximum benefit to each child with epilepsy. An emphasis is placed on preparation for ictal SPECT injection procedures, including the critical role of an automated injector well as the use of state-of-the-art dedicated nuclear medicine imaging and analysis protocols to correctly localize the epileptogenic focus location. In the final section, surgical options, approaches and expected outcomes for the different classes of epilepsy is presented.

Metabolic Therapy for Temporal Lobe Epilepsy in a Dish: Investigating Mechanisms of Ketogenic Diet using Electrophysiological Recordings in Hippocampal Slices

The hippocampus is prone to epileptic seizures and is a key brain region and experimental platform for investigating mechanisms associated with the abnormal neuronal excitability that characterizes a seizure. Accordingly, the hippocampal slice is a common in vitro model to study treatments that may prevent or reduce seizure activity. The ketogenic diet is a metabolic therapy used to treat epilepsy in adults and children for nearly 100 years; it can reduce or eliminate even severe or refractory seizures. New insights into its underlying mechanisms have been revealed by diverse types of electrophysiological recordings in hippocampal slices. Here we review these reports and their relevant mechanistic findings. We acknowledge that a major difficulty in using hippocampal slices is the inability to reproduce precisely the in vivo condition of ketogenic diet feeding in any in vitro preparation, and progress has been made in this in vivo/in vitro transition. Thus far at least three different approaches are reported to reproduce relevant diet effects in the hippocampal slices: (1) direct application of ketone bodies; (2) mimicking the ketogenic diet condition during a whole-cell patch-clamp technique; and (3) reduced glucose incubation of hippocampal slices from ketogenic diet–fed animals. Significant results have been found with each of these methods and provide options for further study into short- and long-term mechanisms including Adenosine triphosphate (ATP)-sensitive potassium (K_ATP) channels, vesicular glutamate transporter (VGLUT), pannexin channels and adenosine receptors underlying ketogenic diet and other forms of metabolic therapy.

Neuropsychological outcomes of subtemporal selective amygdalohippocampectomy via a small craniotomy

OBJECT

The objectives of this study were to describe a novel minimal-access subtemporal approach for selective resection of the amygdala and hippocampus in patients with medically refractory mesial temporal lobe epilepsy (MTLE) due to hippocampal sclerosis, and to analyze the related outcomes.

METHODS

The authors analyzed data from all cases involving patients with unilateral MTLE due to hippocampal sclerosis who were treated with selective amygdalohippocampectomy via the posterior subtemporal approach through a relatively small craniotomy, without a neuronavigation system, at their institution during the period from September 2010 to September 2012. Data were obtained on baseline characteristics, preoperative evaluations of unilateral mesial temporal sclerosis, surgical complications, and Engel class seizure outcomes. All patients underwent memory testing, IQ testing, and language testing.

RESULTS

The mean duration of follow-up was 33.6 months (range 24–48 months). There were no deaths and no cases of significant postoperative morbidity. One patient had a mild complication. At 2-year follow-up, 19 patients were seizure free (Engel Class I outcome). Verbal memory scores obtained at 3 months and at 2 years after surgery were significantly lower than preoperative scores for patients who underwent surgery on the left side of the brain (p < 0.05). Pictorial memory scores were higher following surgery compared with before surgery regardless of whether patients underwent left- or right-sided brain surgery. There was also improvement in performance IQ and total IQ following surgery in both groups. For patients who underwent right-sided brain surgery, verbal comprehension and semantic fluency testing scores were significantly higher at both 3 months and 2 years after surgery than before surgery. For patients who underwent left-sided brain surgery, scores on all language tests were significantly lower at 3 months after surgery than before surgery. Verbal comprehension testing scores returned to the preoperative level at 2 years after surgery.

CONCLUSIONS

The posterior subtemporal approach through a relatively small craniotomy allows adequate exposure and safe resection of mesial temporal structures and effectively reduces medically intractable MTLE. It preserves IQ but may have a detrimental effect on verbal memory and language ability.

Current Topics in Epilepsy Surgery

This article reviews the current topics in the field of epilepsy surgery. Each type of epilepsy is associated with a different set of questions and goals. In mesial temporal lobe epilepsy (MTLE) with hippocampal sclerosis (HS), postoperative seizure outcome is satisfactory. A recent meta-analysis revealed superior seizure outcome after anterior temporal lobectomy compared with selective amygdalohippocampectomy; in terms of cognitive outcome; however, amygdalohippocampectomy may be beneficial. In temporal lobe epilepsy with normal magnetic resonance imaging (MRI), postoperative seizure outcome is not as favorable as it is in MTLE with HS; further improvement of seizure outcome in these cases is necessary. Focal cortical dysplasia is the most common substrate in intractable neocortical epilepsy, especially in children, as well as in MRI-invisible neocortical epilepsy. Postoperative seizure-free outcome is approximately 60–70%; further diagnostic and therapeutic improvement is required. Regarding diagnostic methodology, an important topic currently under discussion is wideband electroencephalogram (EEG) analysis. Although high-frequency oscillations and ictal direct current shifts are considered important markers of epileptogenic zones, the clinical significance of these findings should be clarified further. Regarding alternatives to surgery, neuromodulation therapy can be an option for patients who are not amenable to resective surgery. In addition to vagus nerve stimulation, intracranial stimulation such as responsive neurostimulation or anterior thalamic stimulation is reported to have a modest seizure suppression effect. Postoperative management such as rehabilitation and antiepileptic drug (AED) management is important. It has been reported that postoperative rehabilitation improves postoperative employment status. Pre- and post-operative comprehensive care is mandatory for postoperative improvement of quality of life.

[Amygdalohippocampectomy in treatment of epilepsy in patients with temporal lobe cavernomas]

BACKGROUND

In some cases, single-stage or delayed amygdalohippocampectomy (AHE) can be used for effective treatment of epileptic syndrome upon resection of temporal lobe cavernomas. The efficacy of AHE in treatment of temporal epilepsies is proved in general; however, the indications for surgery in patients with cavernomas are not developed.

OBJECTIVE

The study objective was to evaluate the efficacy and safety AHE in the treatment of epilepsy in patients with temporal lobe cavernomas and to define the indications for surgery.

MATERIAL AND METHODS

Of 14 patients with temporal lobe cavernomas, which manifested as epileptic seizures, 10 patients underwent selective AHE, and 4 patients underwent anteromedial temporal lobectomy. In 12 cases, AHE was performed simultaneously with cavernoma resection. Delayed AHE was carried out in 2 cases. All patients underwent preoperative MRI and EEG. Preoperative video-EEG monitoring was performed in 3 cases. The duration of postoperative follow-up was at least 1 year (mean follow-up was 3.3 years).

RESULTS

Improvement in the epileptic syndrome was observed in all patients. In the postoperative period, 7 patients had no seizures (Engel class IA); of them, 3 patients discontinued anticonvulsants. The surgery outcome depended on the disease duration. Significant postoperative complications in the form of reversible hemiparesis were observed in 1 case.

CONCLUSION

Amygdalohippocampectomy is highly efficient in treatment of severe forms of epilepsy in patients with temporal lobe cavernomas. In the case of long history of typical temporal seizures and pharmacoresistant epilepsy, AHE can be performed simultaneously with cavernoma resection.

Anterior temporal lobectomy versus selective amygdalohippocampectomy in patients with mesial temporal lobe epilepsy

ABSTRACT Objective To contribute our experience with surgical treatment of patients with mesial temporal lobe epilepsy (mTLE) undergoing anterior temporal lobectomy (ATL) or selective amygdalohippocampectomy (SelAH). Method This is a retrospective observational study. The sample included patients with medically refractory mTLE due to unilateral mesial temporal sclerosis who underwent either ATL or SelAH, at Hospital de Clinicas – UFPR, from 2005 to 2012. We report seizure outcomes, using Engel classification, cognitive outcomes, using measurements of verbal and visuospatial memories, as well as operative complications. Result Sixty-seven patients (33 ATL, 34 SelAH) were studied; median follow-up was 64 months. There was no statistically significant difference in seizure or neuropsychological outcomes, although verbal memory was more negatively affected in ATL operations on patients’ dominant hemispheres. Higher number of major complications was observed in the ATL group (p = 0.004). Conclusion Seizure and neuropsychological outcomes did not differ. ATL appeared to be associated with higher risk of complications.

Minimally Invasive Transpalpebral Endoscopic-Assisted Amygdalohippocampectomy

BACKGROUND: Although anterior temporal lobectomy may be a definitive surgical treatment for epileptic patients with mesial temporal sclerosis, it often results in verbal, visual, and cognitive dysfunction. Studies have consistently reported the advantages of selective procedures compared with a standard anterior temporal lobectomy, mainly in terms of neuropsychological outcomes.

OBJECTIVE: To describe a new technique to perform a selective amygdalohippocampectomy (SAH) through a transpalpebral approach with endoscopic assistance.

METHODS: A mini fronto-orbitozygomatic craniotomy through an eyelid incision was performed in 8 patients. Both a microscope and neuroendoscope were used in the surgeries. An anterior SAH was performed in 5 patients who had the diagnosis of temporal lobe epilepsy with mesial temporal sclerosis. One patient had a mesial temporal lesion suggesting a ganglioglioma. Two patients presented mesial temporal cavernomas with seizures originating from the temporal lobe.

RESULTS: The anterior approach allowed removal of the amygdala and hippocampus. The image-guided system and postoperative evaluation confirmed that the amygdala may be accessed and completely removed through this route. The hippocampus was partially resected. All patients have discontinued medication with no more epileptic seizures. The patients with cavernomas and ganglioglioma also had their lesions completely removed. One-year follow-up has shown no visible scars.

CONCLUSION: The anterior route for SAH is a rational and direct approach to the mesial temporal lobe. Anterior SAH is a safe, less invasive procedure that provides early identification of critical vascular and neural structures in the basal cisterns. The transpalpebral approach provides a satisfactory cosmetic outcome.

Gray matter structural compromise is equally distributed in left and right temporal lobe epilepsy

In drug-resistant temporal lobe epilepsy (TLE), MRI studies have shown consistent mesiotemporal and neocortical structural alterations when comparing patients to healthy controls. It remains, however, relatively unclear whether the side of seizure focus differentially impacts the degree of structural damage. This work performed a comprehensive surface-based analysis of mesiotemporal and neocortical morphology on preoperative 1.5 T MRI in 25/35 LTLE/RTLE patients that achieved seizure freedom after surgery (i.e., Engel-I outcome; 7 ± 2 years follow-up), an imaging-independent confirmation of focus lateralization. Compared to 46 age- and sex-matched controls, both TLE groups displayed marked ipsilateral atrophy in mesiotemporal regions, while cortical thinning was bilateral. Direct contrasts between LTLE and RTLE did not reveal significant differences. Bootstrap simulations indicated low reproducibility of observing a between-cohort difference; power analysis revealed that more than 110 patients would be necessary to detect subtle differences. No difference between LTLE and RTLE was confirmed when using voxel-based morphometry, an independent proxy of gray matter volume. Similar results were obtained analyzing a separate 3 T dataset (15/15 LTLE/RTLE patients; Engel-I after 4 ± 2 years follow-up; 42 controls). Our results strongly support equivalent gray matter compromise in left and right TLE. The morphological profile of seizure-free patients, presenting with ipsilateral mesiotemporal and bilateral cortical atrophy, motivates the development of neuromarkers of outcome that consider both mesiotemporal and neocortical structures. Hum Brain Mapp 37:515-524, 2016. © 2015 Wiley Periodicals, Inc.