Directed and acyclic synaptic connectivity in the human layer 2-3 cortical microcircuit

The computational capabilities of neuronal networks are fundamentally constrained by their specific connectivity. Previous studies of cortical connectivity have mostly been carried out in rodents; whether the principles established therein also apply to the evolutionarily expanded human cortex is unclear. We studied network properties within the human temporal cortex using samples obtained from brain surgery. We analyzed multineuron patch-clamp recordings in layer 2-3 pyramidal neurons and identified substantial differences compared with rodents. Reciprocity showed random distribution, synaptic strength was independent from connection probability, and connectivity of the supragranular temporal cortex followed a directed and mostly acyclic graph topology. Application of these principles in neuronal models increased dimensionality of network dynamics, suggesting a critical role for cortical computation.

Defining benchmark outcomes for mesial temporal lobe epilepsy surgery: A global multicenter analysis of 1119 cases

OBJECTIVE

Benchmarking has been proposed to reflect surgical quality and represents the highest standard reference values for desirable results. We sought to determine benchmark outcomes in patients after surgery for drug-resistant mesial temporal lobe epilepsy (MTLE).

METHODS

This retrospective multicenter study included patients who underwent MTLE surgery at 19 expert centers on five continents. Benchmarks were defined for 15 endpoints covering surgery and epilepsy outcome at discharge, 1 year after surgery, and the last available follow-up. Patients were risk-stratified by applying outcome-relevant comorbidities, and benchmarks were calculated for low-risk ("benchmark") cases. Respective measures were derived from the median value at each center, and the 75th percentile was considered the benchmark cutoff.

RESULTS

A total of 1119 patients with a mean age (range) of 36.7 (1-74) years and a male-to-female ratio of 1:1.1 were included. Most patients (59.2%) underwent anterior temporal lobe resection with amygdalohippocampectomy. The overall rate of complications or neurological deficits was 14.4%, with no in-hospital death. After risk stratification, 377 (33.7%) benchmark cases of 1119 patients were identified, representing 13.6%-72.9% of cases per center and leaving 742 patients in the high-risk cohort. Benchmark cutoffs for any complication, clinically apparent stroke, and reoperation rate at discharge were ≤24.6%, ≤.5%, and ≤3.9%, respectively. A favorable seizure outcome (defined as International League Against Epilepsy class I and II) was reached in 83.6% at 1 year and 79.0% at the last follow-up in benchmark cases, leading to benchmark cutoffs of ≥75.2% (1-year follow-up) and ≥69.5% (mean follow-up of 39.0 months).

SIGNIFICANCE

This study presents internationally applicable benchmark outcomes for the efficacy and safety of MTLE surgery. It may allow for comparison between centers, patient registries, and novel surgical and interventional techniques.

Deep histopathology genotype-phenotype analysis of focal cortical dysplasia type II differentiates between the GATOR1-altered autophagocytic subtype IIa and MTOR-altered migration deficient subtype IIb

Focal cortical dysplasia type II (FCDII) is the most common cause of drug-resistant focal epilepsy in children. Herein, we performed a deep histopathology-based genotype-phenotype analysis to further elucidate the clinico-pathological and genetic presentation of FCDIIa compared to FCDIIb. Seventeen individuals with histopathologically confirmed diagnosis of FCD ILAE Type II and a pathogenic variant detected in brain derived DNA whole-exome sequencing or mTOR gene panel sequencing were included in this study. Clinical data were directly available from each contributing centre. Histopathological analyses were performed from formalin-fixed, paraffin-embedded tissue samples using haematoxylin-eosin and immunohistochemistry for NF-SMI32, NeuN, pS6, p62, and vimentin. Ten individuals carried loss-of-function variants in the GATOR1 complex encoding genes DEPDC5 (n = 7) and NPRL3 (n = 3), or gain-of-function variants in MTOR (n = 7). Whereas individuals with GATOR1 variants only presented with FCDIIa, i.e., lack of balloon cells, individuals with MTOR variants presented with both histopathology subtypes, FCDIIa and FCDIIb. Interestingly, 50% of GATOR1-positive cases showed a unique and predominantly vacuolizing phenotype with p62 immunofluorescent aggregates in autophagosomes. All cases with GATOR1 alterations had neurosurgery in the frontal lobe and the majority was confined to the cortical ribbon not affecting the white matter. This pattern was reflected by subtle or negative MRI findings in seven individuals with GATOR1 variants. Nonetheless, all individuals were seizure-free after surgery except four individuals carrying a DEPDC5 variant. We describe a yet underrecognized genotype-phenotype correlation of GATOR1 variants with FCDIIa in the frontal lobe. These lesions were histopathologically characterized by abnormally vacuolizing cells suggestive of an autophagy-altered phenotype. In contrast, individuals with FCDIIb and brain somatic MTOR variants showed larger lesions on MRI including the white matter, suggesting compromised neural cell migration.

Hemispherotomy in Children: A Retrospective Analysis of 152 Surgeries in a Single Center and Predictors for Long-Term Seizure Outcome

OBJECTIVE

Completeness as a predictor of seizure freedom is broadly accepted in epilepsy surgery. We focused on the requirements for a complete hemispherotomy and hypothesized that the disconnection of the insula contributes to a favorable postoperative seizure outcome. We analyzed surgical and non-surgical predictors influencing long-term seizure outcome before and after a modification of our hemispherotomy technique.

METHODS

We retrospectively studied surgical procedures, electro-clinical parameters, MRI results, and follow-up data in all children who had undergone hemispherotomy between 2001 and 2018 at our institution. We used logistic regression models to analyze the influence of different factors on seizure outcome.

RESULTS

152 patients were eligible for seizure outcome analysis only. Of these, 140 cases had complete follow-up data for ≥24 months and provide the basis for the following results. The median age at surgery was 4.3 years (range 0.3-17.9 years). Complete disconnection (including the insular tissue) was achieved in 63.6% (89/140). At two-year follow-up, seizure freedom (Engel class IA) was observed in 34.8% (8/23) with incomplete insular disconnection while this was achieved in 88.8% (79/89) with complete surgical disconnection (p<0.001, OR=10.41). In the latter group (N=89), a potentially epileptogenic contralateral MRI lesion was the strongest predictor for postoperative seizure recurrence (OR=22.20).

SIGNIFICANCE

Complete surgical disconnection is the most important predictor of seizure freedom following hemispherotomy and requires disconnection of the insular tissue at the basal ganglia level. Even if the hemispherotomy is performed completely surgically, a potentially epileptogenic contralateral lesion on preoperative MRI significantly reduces the chances of postoperative seizure freedom.

Ganglioglioma with adverse clinical outcome and atypical histopathological features were defined by alterations in PTPN11/KRAS/NF1 and other RAS-/MAP-Kinase pathway genes

Exome-wide sequencing studies recently described PTPN11 as a novel brain somatic epilepsy gene. In contrast, germline mutations of PTPN11 are known to cause Noonan syndrome, a multisystem disorder characterized by abnormal facial features, developmental delay, and sporadically, also brain tumors. Herein, we performed a deep phenotype-genotype analysis of a comprehensive series of ganglioglioma (GG) with brain somatic alterations of the PTPN11/KRAS/NF1 genes compared to GG with common MAP-Kinase signaling pathway alterations, i.e., BRAFV600E. Seventy-two GG were submitted to whole exome sequencing and genotyping and 84 low grade epilepsy associated tumors (LEAT) to DNA-methylation analysis. In 28 tumours, both analyses were available from the same sample. Clinical data were retrieved from hospital files including disease onset, age at surgery, brain localization, and seizure outcome. A comprehensive histopathology staining panel was available in all cases. We identified eight GG with PTPN11 alterations, copy number variant (CNV) gains of chromosome 12, and the commonality of additional CNV gains in NF1, KRAS, FGFR4 and RHEB, as well as BRAFV600E alterations. Histopathology revealed an atypical glio-neuronal phenotype with subarachnoidal tumor spread and large, pleomorphic, and multinuclear cellular features. Only three out of eight patients with GG and PTPN11/KRAS/NF1 alterations were free of disabling-seizures 2 years after surgery (38% had Engel I). This was remarkably different from our series of GG with only BRAFV600E mutations (85% had Engel I). Unsupervised cluster analysis of DNA methylation arrays separated these tumours from well-established LEAT categories. Our data point to a subgroup of GG with cellular atypia in glial and neuronal cell components, adverse postsurgical outcome, and genetically characterized by complex alterations in PTPN11 and other RAS-/MAP-Kinase and/or mTOR signaling pathways. These findings need prospective validation in clinical practice as they argue for an adaptation of the WHO grading system in developmental, glio-neuronal tumors associated with early onset focal epilepsy.

The genomic landscape across 474 surgically accessible epileptogenic human brain lesions

Understanding the exact molecular mechanisms involved in the etiology of epileptogenic pathologies with or without tumor activity is essential for improving treatment of drug-resistant focal epilepsy. Here, we characterize the landscape of somatic genetic variants in resected brain specimens from 474 individuals with drug-resistant focal epilepsy using deep whole-exome sequencing (>350×) and whole-genome genotyping. Across the exome, we observe a greater number of somatic single-nucleotide variants (SNV) in low-grade epilepsy-associated tumors (LEAT; 7.92 ± 5.65 SNV) than in brain tissue from malformations of cortical development (MCD; 6.11 ± 4 SNV) or hippocampal sclerosis (HS; 5.1 ± 3.04 SNV). Tumor tissues also had the largest number of likely pathogenic variant carrying cells. LEAT had the highest proportion of samples with one or more somatic copy number variants (CNV; 24.7%), followed by MCD (5.4%) and HS (4.1%). Recurring somatic whole chromosome duplications affecting Chromosome 7 (16.8%), chromosome 5 (10.9%), and chromosome 20 (9.9%) were observed among LEAT. For germline variant-associated MCD genes such as TSC2, DEPDC5, and PTEN, germline SNV were frequently identified within large loss of heterozygosity regions, supporting the recently proposed 'second hit' disease mechanism in these genes. We detect somatic variants in twelve established lesional epilepsy genes and demonstrate exome-wide statistical support for three of these in the etiology of LEAT (e.g., BRAF) and MCD (e.g., SLC35A2 and MTOR). We also identify novel significant associations for PTPN11 with LEAT and NRAS Q61 mutated protein with a complex MCD characterized by polymicrogyria and nodular heterotopia. The variants identified in NRAS are known from cancer studies to lead to hyperactivation of NRAS, which can be targeted pharmacologically. We identify large recurrent 1q21-q44 duplication including AKT3 in association with focal cortical dysplasia type 2a with hyaline astrocytic inclusions, another rare and possibly under-recognized brain lesion. The clinical genetic analyses showed that the numbers of somatic SNV across the exome and the fraction of affected cells were positively correlated with the age at seizure onset and surgery in individuals with LEAT. In summary, our comprehensive genetic screen sheds light on the genome-scale landscape of genetic variants in epileptic brain lesions, informs the design of gene panels for clinical diagnostic screening, and guides future directions for clinical implementation of epilepsy surgery genetics.

Epilepsy Surgery in Extratemporal vs Temporal Lobe Epilepsy: Changes in Surgical Volumes and Seizure Outcome Between 1990 and 2017

Objective:

Seizure outcome after extratemporal lobe epilepsy (exTLE) surgery has often been poorer than after temporal lobe epilepsy (TLE) surgery, but recent improvements in diagnostics and surgery may have changed this. Our aim was to analyze the changes in presurgical and surgical volumes and seizure outcome two years after surgery for patients with exTLE compared to those with TLE.

Methods:

We performed a retrospective, single-center cohort study including patients from the Bethel presurgical-surgical-postsurgical database from 1990 to 2017. We used logistic regression to analyze factors influencing the odds for surgery and the odds for seizure freedom after surgery.

Results:

We included 3822 patients with presurgical evaluation, 2404 of whom had subsequently undergone surgery. The proportion of exTLE patients in presurgical evaluation increased from 41% between 1990-1993 to 64% in 2014-2017. The odds for surgery decreased over time (2003-2011: OR=0.50 [95%CI 0.36-0.70]; 2012-2017: OR=0.24 [CI 0.17-0.35]; reference: 1990-2002), and patients with exTLE had lower odds for surgery than TLE patients, but this difference diminished over time (exTLE vs. TLE 1990-2002: OR=0.14 [CI 0.09-0.20]; 2003-2011: OR=0.32 [CI 0.24-0.44]; 2012-2017: OR=0.46 [CI 0.34-0.63]). Etiology, the side of the epileptogenic lesion and invasive recordings additionally influenced the odds for surgery. The most frequent reasons for not undergoing surgery were the missing identification of a circumscribed epileptogenic zone or an unacceptable risk of postsurgical deficits in exTLE patients and the patient’s decision in TLE patients. Compared to TLE patients, the odds for seizure freedom after surgery started lower for patients with exTLE in earlier years, but increased (≤2 lobes 1990-2002: OR=0.47 [CI 0.33-0.68]; 2003-2011: OR=0.62 [CI 0.44-0.87]; 2012-2017: OR=0.78 [CI 0.53-1.15]; ≥3 lobes 1990-2002: OR=0.37 [CI 0.22-0.62]; 2003-2011: OR=0.73 [CI 0.43-1.23]; 2012-2017: OR=1.46 [CI 0.91-2.42]). Etiology, age at surgery and invasive recordings were further predictors for the odds for seizure freedom.

Conclusion:

Over the past 28 years, the success of resective surgery for patients with exTLE has improved. At the same time, the number of exTLE patients being evaluated for surgery increased as well as their odds for undergoing surgery.

DNA methylation-based classification of malformations of cortical development in the human brain

Malformations of cortical development (MCD) comprise a broad spectrum of structural brain lesions frequently associated with epilepsy. Disease definition and diagnosis remain challenging and are often prone to arbitrary judgment. Molecular classification of histopathological entities may help rationalize the diagnostic process. We present a retrospective, multi-center analysis of genome-wide DNA methylation from human brain specimens obtained from epilepsy surgery using EPIC 850 K BeadChip arrays. A total of 308 samples were included in the study. In the reference cohort, 239 formalin-fixed and paraffin-embedded (FFPE) tissue samples were histopathologically classified as MCD, including 12 major subtype pathologies. They were compared to 15 FFPE samples from surgical non-MCD cortices and 11 FFPE samples from post-mortem non-epilepsy controls. We applied three different statistical approaches to decipher the DNA methylation pattern of histopathological MCD entities, i.e., pairwise comparison, machine learning, and deep learning algorithms. Our deep learning model, which represented a shallow neuronal network, achieved the highest level of accuracy. A test cohort of 43 independent surgical samples from different epilepsy centers was used to test the precision of our DNA methylation-based MCD classifier. All samples from the test cohort were accurately assigned to their disease classes by the algorithm. These data demonstrate DNA methylation-based MCD classification suitability across major histopathological entities amenable to epilepsy surgery and age groups and will help establish an integrated diagnostic classification scheme for epilepsy-associated MCD.

Enhancing Safety in Epilepsy Surgery (EASINESS): Study Protocol for a Retrospective, Multicenter, Open Registry

Introduction: Optimizing patient safety and quality improvement is increasingly important in surgery. Benchmarks and clinical quality registries are being developed to assess the best achievable results for several surgical procedures and reduce unwarranted variation between different centers. However, there is no clinical database from international centers for establishing standardized reference values of patients undergoing surgery for mesial temporal lobe epilepsy.

Design: The Enhancing Safety in Epilepsy Surgery (EASINESS) study is a retrospectively conducted, multicenter, open registry. All patients undergoing mesial temporal lobe epilepsy surgery in participating centers between January 2015 and December 2019 are included in this study. The patient characteristics, preoperative diagnostic tools, surgical data, postoperative complications, and long-term seizure outcomes are recorded.

Outcomes: The collected data will be used for establishing standardized reference values (“benchmarks”) for this type of surgical procedure. The primary endpoints include seizure outcomes according to the International League Against Epilepsy (ILAE) classification and defined postoperative complications.

Discussion: The EASINESS will define robust and standardized outcome references after amygdalohippocampectomy for temporal lobe epilepsy. After the successful definition of benchmarks from an international cohort of renowned centers, these data will serve as reference values for the evaluation of novel surgical techniques and comparisons among centers for future clinical trials.

Clinical trial registration: This study is indexed at clinicaltrials.gov (NT 04952298).

Development and Validation of Prediction Models for Developmental and Intellectual Outcome Following Pediatric Epilepsy Surgery

BACKGROUND AND OBJECTIVES

To (1) identify predictors of postoperative intelligence and developmental quotients (IQ/DQ) and (2) develop and validate clinically applicable IQ/DQ prediction models.

METHODS

We retrospectively analyzed neuropsychological outcomes and their possible determinants for children treated in Bethel and Utrecht since 1990. We performed separate analyses for patients with IQ and those with only DQ available. We developed prediction models based on presurgical determinants to predict dichotomized levels of performance (IQ≥85, IQ≥70, DQ≥50).

RESULTS

IQ/DQ data before and two years after surgery were available for 492 patients (IQ n=365, DQ n=127). At a cutoff-level ±10 points, the chance of improvement was considerably higher than the chance of deterioration (IQ 37.3% vs. 6.6% and DQ 31.5% vs. 15.0%, respectively). Presurgical IQ/DQ was the strongest predictor of postoperative cognition (IQ r=0.85, p<.001, DQ: r=0.57, p<.001).Two IQ models were developed in the Bethel cohort (n=258) and externally validated in the Utrecht cohort (n=102). For DQ, we developed the model in the Bethel cohort and used 10-fold cross-validation. Models allowed good prediction at all three cutoff-levels (correct classification for IQ≥85=86%, IQ≥70=91%, DQ≥50=76%). External validation of the IQ models showed high accuracy (IQ≥85: 0.82, CI 0.75-0.91, IQ≥70: 0.84, CI 0.77-0.92) and excellent discrimination (ROC curves IQ≥85: AUC 0.90, CI 0.84-0.96; IQ≥70: AUC 0.92, CI 0.87-0.97).

DISCUSSION

After epilepsy surgery in children, the risk of cognitive deterioration is very low. Presurgical development has a strong impact on the postoperative trajectory. The presented models can improve presurgical counseling of patients and parents by reliably predicting cognitive outcomes.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that for children undergoing epilepsy surgery presurgical IQ/DQ was the strongest predictor of postoperative cognition.

Clinical characteristics and postoperative seizure outcome in patients with mild malformation of cortical development and oligodendroglial hyperplasia

OBJECTIVE

We describe for the first time clinical characteristics in a series of 20 pre-surgically investigated patients with mild malformation of cortical development with oligodendroglial hyperplasia (MOGHE) who were operated on in our epilepsy center. We aimed to better diagnose this entity and help surgical planning.

METHODS

Data on 20 patients with histologically confirmed MOGHE were retrospectively evaluated as to age at epilepsy onset and operation, seizure semiology, magnetic resonance imaging (MRI) localization, electroencephalography (EEG) patterns, extent of the operative resection, and postoperative seizure outcome.

RESULTS

Epilepsy began mainly in early childhood; however, symptoms did not manifest until adolescence or adulthood in 30% of patients. All patients had pathologic MRI findings. In 45% of patients the lesion was initially overlooked. Most commonly, the lesion was seen in the frontal lobe. Seizure semiology was characterized as follows: (1) epileptic spasms at epilepsy onset were common and (2) nocturnal hyperkinetic seizures during the course of the disease were rare. EEG always showed frequent interictal epileptic discharges. Two peculiar patterns were observed: (1) during sleep stage I-II, sub-continuous repetitive (0.5-1.5/s) unilateral plump spike/polyspike slow waves were seen and (2) during wakefulness, unilateral paroxysms of 2-2.5/s spike-wave complexes occurred. In total, 60% of patients were seizure-free 1 year postoperatively. Postoperative seizure outcome was positively correlated with the extent of resection, age at epilepsy onset, and age at operation. Postoperative long-term outcomes remained stable in patients undergoing larger operations.

SIGNIFICANCE

MRI, EEG, and semiology already contribute to the diagnosis of probable MOGHE preoperatively. Because postoperative seizure outcomes depend on the extent of the resection, prior knowledge of a probable MOGHE helps to plan the resection and balance the risks and benefits of such an intervention. In patients undergoing larger operations, epilepsy surgery achieved good postoperative results; the first long-term outcome data were stable in these patients.

Reading and the visual word form area (VWFA) - Management and clinical experience at one epilepsy surgery center

OBJECTIVE

Presurgical evaluation has no established routine to assess reading competence and to identify essential "not to resect" reading areas. Functional models describe a visual word form area (VWFA) located in the midfusiform gyrus in the dominant ventral occipito-temporal cortex (vOTC) as essential for reading. We demonstrate the relevance and feasibility of invasive VWFA-mapping.

METHODS

Four patients with epilepsy received invasive VWFA-mapping via left temporo-basal strip-electrodes. Co-registration of the results and additional data from the literature led to the definition of a region of interest (ROI) for a retrospective assessment of postoperative reading deficits by a standardized telephone-interview in patients with resections in this ROI between 2004 and 2018.

RESULTS

Electrical cortical stimulation disturbed whole word recognition and reading in four patients with structural epilepsy. Stimulation results showed distribution in the basal temporal lobe (dorsal mesencephalon to preoccipital notch). We identified 34 patients with resections in the ROI of the dominant hemisphere. Of these, 15 (44.1%) showed a postoperative reading deficit with a mean duration of 18.2 months (+/-32.4, 0.5-122). Six patients suffered from letter-by-letter (LBL) reading. Two patients had permanent LBL reading after resection in the ROI.

SIGNIFICANCE

We present evidence on the functional relevance of the vOTC for reading by (1) extra-operative cortical stimulation of the VWFA and by (2) a retrospective case study of reading deficits in patients operated in this area. Reading assessments and data concerning essential reading structures should be included in the presurgical evaluation of patients with lesions in the left vOTC.

Stereotactic depth electrode placement surgery in paediatric and adult patients with the Neuromate robotic device: Accuracy, complications and epileptological results

OBJECTIVE

The number of patients requiring depth electrode implantation for invasive video EEG diagnostics increases in most epilepsy centres. Here we report on our institutional experience with frameless robot-assisted stereotactic placement of intracerebral depth electrodes using the Neuromate® stereotactic robot-system.

METHODS

We identified all patients who had undergone robot-assisted stereotactic placement of intracerebral depth electrodes for invasive extra-operative epilepsy monitoring between September 2013 and March 2020. We studied technical (placement) and diagnostic accuracy of the robot-assisted procedure, associated surgical complications and procedural time requirements.

RESULTS

We evaluated a total of 464 depth electrodes implanted in 74 patients (mean 6 per patient, range 1-12). There were 27 children and 47 adults (age range: 3.6-64.6 yrs.). The mean entry and target point errors were 1.82±1.15 and 1.98±1.05 mm. Target and entry point errors were significantly higher in paediatric vs. adult patients and for electrodes targeting the temporo-mesial region. There were no clinically relevant haemorrhages and no infectious complications. Mean time for the placement of one electrode was 37±14 min and surgery time per electrode decreased with the number of electrodes placed. 55 patients (74.3%) underwent definitive surgical treatment. 36/51 (70.1%) patients followed for >12 months or until seizure recurrence became seizure-free (ILAE I).

CONCLUSION

Frameless robot-guided stereotactic placement of depth electrodes with the Neuromate® stereotactic robot-system is safe and feasible even in very young children, with good in vivo accuracy and high diagnostic precision. The surgical workflow is time-efficient and further improves with increasing numbers of implanted electrodes.

Hyperkinetic Seizures with Ictal Fear as Localizing Ictal Signs in MRI-Negative Medial Frontal Lobe Epilepsy

PURPOSE

Hyperkinetic seizures are described as seizure onset in the frontal or temporal lobe. Additional localizing information is important for diagnostic workup and surgical therapy. We describe diagnostic workup and surgical outcomes in three patients with pharmacoresistant focal emotional seizures with hyperkinetic elements.

METHODS/RESULTS

High-resolution 3 Tesla (T) magnetic resonance imaging (MRI) did not reveal clear-cut lesions. Invasive video-electroencephalography (EEG) with depth electrodes along the cingulate sulcus (bilateral; patients 1 and 3), right; patient 2 provided congruent results for a circumscribed seizure onset zone within the medial frontal lobe (right: patients 1 and 2; left: patient 3). Topectomies were performed in all patients. Histopathology revealed a small focal cortical dysplasia in the three cases (focal cortical dysplasia [FCD] IIA: patient 1; FCD IIB: patients 2 and 3). All patients remained completely seizure-free since surgery (Engel 1A; follow-up: 9-28 months).

CONCLUSION

Ictal fear associated with hyperkinetic semiology points to a seizure-onset zone within the anteromedial frontal lobe (anterior cingulate gyrus). Ictal semiology is crucial for the placement of depth electrodes, especially in MRI-negative cases. These cases illustrate a clinical advantage to the new International League against Epilepsy (ILAE) seizure classification, emphasizing initial clinical symptoms.

Mosaic trisomy of chromosome 1q in human brain tissue associates with unilateral polymicrogyria, very early-onset focal epilepsy, and severe developmental delay

Polymicrogyria (PMG) is a developmental cortical malformation characterized by an excess of small and frustrane gyration and abnormal cortical lamination. PMG frequently associates with seizures. The molecular pathomechanisms underlying PMG development are not yet understood. About 40 genes have been associated with PMG, and small copy number variations have also been described in selected patients. We recently provided evidence that epilepsy-associated structural brain lesions can be classified based on genomic DNA methylation patterns. Here, we analyzed 26 PMG patients employing array-based DNA methylation profiling on formalin-fixed paraffin-embedded material. A series of 62 well-characterized non-PMG cortical malformations (focal cortical dysplasia type 2a/b and hemimegalencephaly), temporal lobe epilepsy, and non-epilepsy autopsy controls was used as reference cohort. Unsupervised dimensionality reduction and hierarchical cluster analysis of DNA methylation profiles showed that PMG formed a distinct DNA methylation class. Copy number profiling from DNA methylation data identified a uniform duplication spanning the entire long arm of chromosome 1 in 7 out of 26 PMG patients, which was verified by additional fluorescence in situ hybridization analysis. In respective cases, about 50% of nuclei in the center of the PMG lesion were 1q triploid. No chromosomal imbalance was seen in adjacent, architecturally normal-appearing tissue indicating mosaicism. Clinically, PMG 1q patients presented with a unilateral frontal or hemispheric PMG without hemimegalencephaly, a severe form of intractable epilepsy with seizure onset in the first months of life, and severe developmental delay. Our results show that PMG can be classified among other structural brain lesions according to their DNA methylation profile. One subset of PMG with distinct clinical features exhibits a duplication of chromosomal arm 1q.

Operative posterior disconnection in epilepsy surgery: Experience with 29 patients

OBJECTIVE

It has been suggested that multilobar epilepsies caused by lesions restricted to the posterior cerebral quadrant (ie, the parietal, temporal, and occipital lobes) can be treated successfully by a procedure termed posterior disconnection. The objective of the present paper was to identify determinants of the epileptological outcome following posterior disconnection surgery.

METHODS

The authors retrospectively analyzed a series of 29 consecutive patients undergoing posterior disconnection surgery between 2005 and 2017 for the treatment of refractory posterior quadrantic epilepsy. Specifically, all presurgical and postoperative magnetic resonance (MR) studies were reviewed to identify cases with an incomplete disconnection, or the presence of a more widespread pathology involving the whole hemisphere rather than only its posterior quadrant. In addition, we reevaluated all presurgical video-electroencephalography (EEG) reports.

RESULTS

Seizure-free (International League Against Epilepsy [ILAE] 1) after surgery were 3/3 patients with EEG findings restricted to the posterior quadrant, 0/7 patients who had propagation of epileptic activity to the contralateral frontal lobe, and 11/19 (57.9%) who showed propagation to ipsilateral frontal and/or contralateral posterior. Eleven of 13 (84.6%) patients with purely posterior quadrantic magnetic resonance imaging (MRI) findings (as retrospectively diagnosed by neuroimaging) vs 3/16 (18.8%) cases with additional subtle abnormalities outside the posterior quadrant became seizure-free (P = .001). Eleven of 16 (68.8%) patients with complete disconnections were seizure-free vs only 3/13 (23.0%) cases with leftover temporal lobe tissue with contact to the insula (P = .025, both Fisher's exact test).

SIGNIFICANCE

A posterior disconnection is a technically demanding but very effective operation for posterior quadrantic epilepsy. Good epileptologic outcomes require not only that the epileptogenic lesion does not extend beyond the confines of the disconnected cerebral volume but also the absence of subtle MRI abnormalities, more widespread than the clear-cut lesion of the posterior quadrant. Hemispheric or contralateral (particularly frontal) propagation of the epileptic activity may also indicate the presence of a hemispheric rather than posterior quadrantic pathology.

Partial resection of presurgical fMRI activation is associated with a postsurgical loss of language function after frontal lobe epilepsy surgery

We describe five patients with frontal lobe epilepsy who underwent electrocortical stimulation (ES) for language localization and language functional magnetic resonance imaging (fMRI) prior to epilepsy surgery. Six months after surgery, three patients suffered from a drop of verbal fluency. In all of them, frontal areas with presurgical language fMRI activity were resected. Our results suggest that resection in regions of areas with presurgical fMRI activation is not without risk for a postsurgical loss of function, even when ES results were negative for language function in these areas. Using fMRI activations might be specifically helpful to plan the resection when ES delivered inconclusive results.

Trends in epilepsy surgery: stable surgical numbers despite increasing presurgical volumes

INTRODUCTION

Despite the success of epilepsy surgery, recent reports suggest a decline in surgical numbers. We tested these trends in our cohort to elucidate potential reasons.

PATIENTS AND METHODS

Presurgical, surgical and postsurgical data of all patients undergoing presurgical evaluation in between 1990 and 2013 were retrospectively analysed. Patients were grouped according to the underlying pathology.

RESULTS

A total of 3060 patients were presurgically studied, and resective surgery was performed in 66.8% (n=2044) of them: medial temporal sclerosis (MTS): n=675, 33.0%; benign tumour (BT): n=408, 20.0%; and focal cortical dysplasia (FCD): n=284, 13.9%. Of these, 1929 patients (94.4%) had a follow-up of 2 years, and 50.8% were completely seizure free (Engel IA). Seizure freedom rate slightly improved over time. Presurgical evaluations continuously increased, whereas surgical interventions did not. Numbers for MTS, BT and temporal lobe resections decreased since 2009. The number of non-lesional patients and the need for intracranial recordings increased. More evaluated patients did not undergo surgery (more than 50% in 2010-2013) because patients were not suitable (mainly due to missing hypothesis: 4.5% in 1990-1993 up to 21.1% in 2010-2013, total 13.4%) or declined from surgery (maximum 21.0% in 2010-2013, total 10.9%). One potential reason may be that increasingly detailed information on chances and risks were given over time.

CONCLUSIONS

The increasing volume of the presurgical programme largely compensates for decreasing numbers of surgically remediable syndromes and a growing rate of informed choice against epilepsy surgery. Although comprehensive diagnostic evaluation is offered to a larger group of epilepsy patients, surgical numbers remain stable.

Mild Malformation of Cortical Development with Oligodendroglial Hyperplasia in Frontal Lobe Epilepsy: A New Clinico-Pathological Entity

The histopathological spectrum of human epileptogenic brain lesions is widespread including common and rare variants of cortical malformations. However, 2-26% of epilepsy surgery specimens are histopathologically classified as nonlesional. We hypothesized that these specimens include also new diagnostic entities, in particular when presurgical magnetic resonance imaging (MRI) can identify abnormal signal intensities within the anatomical region of seizure onset. In our series of 1381 en bloc resected epilepsy surgery brain specimens, 52 cases could not be histopathologically classified and were considered nonlesional (3.7%). An increase of Olig2-, and PDGFR-alpha-immunoreactive oligodendroglia was observed in white matter and deep cortical layers in 22 of these patients (42%). Increased proliferation activity as well as heterotopic neurons in white matter were additional histopathological hallmarks. All patients suffered from frontal lobe epilepsy (FLE) with a median age of epilepsy onset at 4 years and 16 years at epilepsy surgery. Presurgical MRI suggested focal cortical dysplasia (FCD) in all patients. We suggest to classify this characteristic histopathology pattern as "mild malformation of cortical development with oligodendroglial hyperplasia (MOGHE)." Further insights into pathomechanisms of MOGHE may help to bridge the diagnostic gap in children and young adults with difficult-to-treat FLE.

Muscle and nerve pathology in Dunnigan familial partial lipodystrophy

OBJECTIVE

To characterize muscle and nerve pathology in Dunnigan familial partial lipodystrophy (FPLD).

METHODS

We used conventional histology, immunohistochemistry, messenger RNA (mRNA) expression, gene sequencing, and clinical studies of 13 patients with neuromuscular involvement.

RESULTS

The clinical findings consisted of muscle hypertrophy (12/13), severe myalgias (9/13), and multiple nerve entrapment syndromes (8/13). Skeletal muscle histology demonstrated marked Type 1 and 2 muscle fiber hypertrophy and nonspecific myopathic changes, whereas numerous paranodal myelin swellings (tomacula) were found in sural nerve biopsies. We found that myostatin mRNA expression was reduced in patients with FPLD vs controls. We sequenced the myostatin gene in our subjects, but found no mutations. We then investigated whether or not SMAD, the intracellular mediator of myostatin signaling, might be impaired in patients with FPLD. We found that in FPLD muscle, a large number of SMAD molecules adhered to the nuclear membrane and were not found within the nucleus, compared with normal muscle or muscle from a patient with a non-FPLD lamin A/C disease.

CONCLUSION

The myopathy and neuropathy associated with Dunnigan familial partial lipodystrophy are distinct from other lamin A/C disorders. We hypothesize that the lipodystrophy-associated mutation interferes with SMAD signaling, linking this type of lipodystrophy to the phenotypically similar myostatin deficiency.

Spontaneous intracerebral hemorrhage and multiple infarction in Williams-Beuren syndrome

A 7-year-old boy diagnosed with Williams-Beuren syndrome was admitted for spontaneous right hemispheric intracerebral hemorrhage. Cerebral angiography did not reveal any source of bleeding. After a short period of clinical improvement under conservative treatment, the boy deteriorated rapidly. CT showed the beginning of a complete infarction of both hemispheres. Operative evacuation of the bleeding and bilateral osteoclastic decompression had no perceptible influence on the clinical course. To the present day, the boy has remained in a vegetative state. Reports in the literature suggest that Williams syndrome with cerebral infarction is associated with a markedly poorer prognosis when there is additional intracerebral bleeding.

Late neurological deterioration 30 years following conservative treatment of a lower cervical spine fracture--a case report

A today 44 years old man suffered from a compression and subluxation fracture of C 4 and C 5 vertebral body during a swimming accident in 1971. The primary therapy was conservative and the patient was rehabilitated. Since 1997 the patient showed a slowly progressive right hemiparesis with signs of cervical myelopathy. The diagnostic procedures revealed a severe deformity of the cervical spine with myelon compression. We performed an operation with replacement of C4 and C5 and dorsal stabilization at the same time. This very impressive case shows the risk of a late and slowly onset of myelopathic deterioration while latent bony instability persist post traumatic. The authors think in agreement with the actual literature that the early operative stabilization of instable fractures of the lower cervical spine is inevitable. According to the grade of neurological and bony damage the operation should not be performed later than 8-12 hours after injury.

Local immunosuppression with budesonide after liver transplantation in the rat: a preliminary histomorphological analysis

BACKGROUND

In this study we have analyzed the local immunosuppression with budesonide, a topically selective glucocorticosteroid, in rats after orthotopic liver transplantation. Because of its high first-pass hepatic clearance budesonide can be given orally, achieving high intrahepatic and low systemic concentrations.

METHODS

Using an acute rejection model from Dark Agouti (DA) to Lewis rats, the histomorphological degree of rejection was assessed on histological sections at the ninth postoperative day.

RESULTS

Livers of the DA to Lewis study group without immunosuppression revealed severe allograft rejection with vast cellular infiltrates, massive endothelialitis, and hepatocyte necrosis. In the three budesonide study groups (250 microg, 500 microg, and 1 mg/kg/day) a moderate to mild liver allograft rejection was seen. Rejection was most prominent in the 250 microg group, whereas the 1 g group showed almost no signs of rejection, similar to the Lewis to Lewis control group. Aspartate and alanine transaminase (sGOT, sGPT) as well as alkaline phosphatase serum levels correlated with the degree of rejection, achieving highest levels in the DA to Lewis group without immunosuppression. Animals treated with 1 g of budesonide had serum levels similar to Lewis to Lewis control animals.

CONCLUSIONS

These results implicate a beneficial effect of local immunosuppression with budesonide in rats based on the histomorphological degree of liver allograft rejection.