Location of periventricular nodular heterotopia is related to the malformation phenotype on MRI

Laser Ablation of Periventricular Nodular Heterotopia for Medically Refractory Epilepsy

OBJECTIVE

Periventricular nodular heterotopia (PVNH) is the most common neuronal heterotopia, frequently resulting in pharmaco-resistant epilepsy. Here, we characterize variables that predict good epilepsy outcomes following surgical intervention using stereo-electroencephalography (SEEG) -informed magnetic resonance-guided laser interstitial thermal therapy (MRgLITT).

METHODS

A retrospective review of consecutive cases from a single high-volume epilepsy referral center identified patients who underwent SEEG evaluation for PVNH to characterize the intervention and outcomes.

RESULTS

Thirty-nine patients underwent SEEG-guided MRgLITT of the seizure onset zone (SoZ) in PVNH and associated epileptic tissue. PVNH and polymicrogyria (PMG) were densely sampled with a mean of 16.5 (SD = 2)/209.4 (SD = 36.9) SEEG probes/recording contacts per patient. Ablation principally targeted just the PVNH and cortex that was abnormal on imaging was ablated (5 patients) only if implicated in the SoZ. Volumetric analyses revealed a high percentage of PVNH SoZ ablation (96.6%, SD = 5.3%) in unilateral and bilateral (92.9%, SD = 7.2%) cases. Mean follow-up duration was 31.4 months (SD = 20.9). Seizure freedom (ILAE 1) was excellent: unilateral PVNH without other imaging abnormalities, 80%; PVNH with mesial temporal sclerosis (MTS) or PMG, 63%; bilateral PVNH, 50%. SoZ ablation percentage significantly impacted surgical outcomes (p < 0.001).

INTERPRETATION

PVNH plays a central role in seizure genesis as revealed by dense recordings and selective targeting by LITT. MRgLITT represents a transformative technological advance in PVNH-associated epilepsy with seizure control outcomes consistent with those seen in focal lesional epilepsies. In localized unilateral cases and otherwise normal imaging, PVNH ablation without invasive recordings may be considered, and this approach deserves to be explored further. ANN NEUROL 2024;96:1174-1184.

Anomalies of Midbrain/Hindbrain Development: Malformations of Cerebellum: Diagnosis, Classification, and Rehabilitative Hypothesis

Extensive research has been conducted on the cerebellum, making it one of the most thoroughly investigated regions of the brain. It plays a fundamental role not only in motor control but also in motor learning and cognition. The development of the cerebellum is a lengthy process, beginning during the embryonic period up to the first years of life. This slow and protracted process makes it a vulnerable organ liable to different insults, responsible for many developmental disorders such as Dandy–Walker syndrome, medulloblastoma, dystroglicanopathy, pontocerebellar hypoplasia, thubulinopathies, and Jubert syndrome. Due to several factors, the true prevalence of cerebellar malformations is not known in most cases. The cerebellum undergoes development through following four fundamental stages:

(1) Identification of the cerebellar region at the boundary between the midbrain and hindbrain.

(2) Establishment of two cell proliferation compartments: firstly, Purkinje cells and deep cerebellar nuclei emerge from the ventricular zone of the metencephalic alar plate; secondly, granule cell precursors are generated from a separate proliferation compartment known as the upper rhombic lip.

(3) Migration of granule cells toward the interior: granule precursor cells constitute the external granular layer (EGL), and during the initial postnatal year, granule cells migrate inward to their final position in the internal granular layer.

(4) Formation of cerebellar circuitry and subsequent differentiation.

Based on different types of involvement of the structures detected in the brain magnetic resonance, the classification of brainstem and cerebellar anomalies is divided into three categories: (1) mainly the cerebellum, (2) mainly the brain stem, and (3) both involved. This review will outline the developmental processes of the cerebellum and delve into common developmental disorders associated with it, including the Dandy–Walker syndrome, cerebellar hypoplasia, rhomboencephalosynapsis, lissencephaly, and gray matter heterotopias.

Periventricular Heterotopias: Neuroependymal Abnormalities

Periventricular nodular heterotopia (PVNH) is a group of malformation of cortical development characterized by ectopic neuronal nodules, located along the lateral ventricles. Magnetic resonance imaging can identify gray matter nodules located in wall of ventricles, which appear as island having the same signal of gray matter within white matter. The symptomatological spectrum is various, but the most common clinical presentation is with epileptic seizures, often a drug-resistant type. Features as severity, age of presentation, and associated malformations depend on the underlying etiology. From a genetic point of view, FLNA1 and ERMARD are acknowledged to be the main target of mutations that cause PVNH, although recently many other genes have shown a clear pathogenetic involvement. PVNH may manifest as a solitary discovery in brain imaging or present in conjunction with various other brain or systemic abnormalities. The diagnosis of PVNH is mainly carried out with electroneurophysiological and neuroimaging examinations, while the etiological diagnosis is made with genetic investigations. Treatment consists of use of anticonvulsant drugs, but no significant difference exists among them. In addition, frequently, PVNH-related seizures show poor response to drug, leading to requirement for surgical treatment, performed taking advantages from stereotactic ablative techniques that have a meaningful impact on surgical outcome.

Stereo-electroencephalography-guided radiofrequency thermocoagulation restricted to periventricular nodular heterotopias in patients with drug-resistant epilepsy: A single center experience

INTRODUCTION

Periventricular nodular heterotopias (PVNH) are developmental abnormalities with neurons abnormally clustered around the cerebral ventricles. Patients frequently present with focal drug-resistant epilepsy (DRE). However, the relationship between PVNH and the seizure onset zone (SOZ) is complex. Stereo-electroencephalography (SEEG) is an invasive diagnostic procedure for patients with DRE. In selected patients, the SEEG may be converted into a therapeutic procedure, lesioning the probable (SOZ) with pulsed radiofrequency thermocoagulation (RFTC). The aim of our study was to evaluate the efficacy and safety of SEEG-RFTC in a series of DRE patients with PVNH.

METHODS

Twenty-four patients with focal DRE related to PVNH and treated with SEEG-guided-RFTC restricted to nodules were prospectively collected between 2016 and 2023 and retrospectively analyzed after a follow-up of at least 12 months.

RESULTS

Seventeen patients (71 %) responded (ILAE class 1-4) after SEEG-guided RFTC of whom eleven (46 %) became seizure-free (class 1) at last follow up, nine (45 %) despite residual PVNH tissue on MRI. SEEG seizure onset was restricted to PVNH in eleven patients (class 1 in 45 %) and simultaneously in PVNH and other cortical areas in thirteen patients (class 1 in 46 %). Out of 31 SEEG-RFTC procedures in twenty-four patients, adverse events, related to RFTC, were recorded in eight (26 %), of which two patients (8 %) had predicted permanent visual complaints whilst the other five had transient complaints.

SIGNIFICANCE

This study demonstrates that a considerable percentage of patients, even with bilateral, multiple PVNH and involvement of adjacent cortical regions can be rendered seizure-free with SEEG-guided-RFTC restricted to the nodules. Furthermore, this study delivers evidence that the complete destruction of the entire nodule is not necessary to render a patient seizure free. This justifies the use of SEEG in patients with single, multiple or bilateral PVNHs to provide insight into the epileptogenic organization in and around these lesions.

Stereo-EEG-based ictal functional connectivity in patients with periventricular nodular heterotopia-related epilepsy

Nodular heterotopia (NH)-related drug-resistant epilepsy is challenging due to the deep location of the NH and the complexity of the underlying epileptogenic network. Using ictal stereo-electroencephalography (SEEG) and functional connectivity (FC) analyses in 14 patients with NH-related drug-resistant epilepsy, we aimed to determine the leading structure during seizures. For this purpose, we compared node IN and OUT strength between bipolar channels inside the heterotopia and inside gray matter, at the group level and at the individual level. At seizure onset, the channels within NH belonging to the epileptogenic and/or propagation network showed higher node OUT-strength than the channels within the gray matter (p = .03), with higher node OUT-strength than node IN-strength (p = .03). These results are in favor of a "leading" role of NH during seizure onset when involved in the epileptogenic- or propagation-zone network (50% of patients). However, when looking at the individual level, no significant difference between NH and gray matter was found, except for one patient (in two of three seizures). This result confirms the heterogeneity and the complexity of the epileptogenic network organization in NH and the need for SEEG exploration to characterize more precisely patient-specific epileptogenic network organization.

Case report: Periventricular heterotopia and early-onset bipolar disorder in adolescent patient with history of childhood attention deficit hyperactivity disorder

Periventricular heterotopia (PH) is a developmental malformation in the brain. Because the clinical symptoms are heterogeneous, few studies have investigated the psychiatric symptoms associated with PH. We describe the case of a 17-year-old male with bipolar disorder (BD), who had been treated for attention deficit-hyperactivity disorder (ADHD) and developmental delay in childhood. He had experienced depression for 1 year and was admitted to the emergency room following a suicide attempt. He was admitted to the psychiatric ward for further evaluation and treatment for elated mood, decreased need for sleep, increased sexuality, and delusion. The patient was diagnosed with BP-I disorder and PH via brain magnetic resonance imaging. After combined treatment with valproic acid and aripiprazole, his manic symptoms stabilized. To our knowledge, this is the first report of an adolescent PH case with a history of early onset BD and ADHD in childhood.

Unveiling the intriguing puzzle: Nodular heterotopia and Mega Cisterna Magna in an adult female

The co-occurrence of Mega Cisterna Magna and Periventricular Nodular Heterotopia in an adult female patient is an uncommon and intriguing observation. Most instances are X-linked, typically with the Xq28-localized filamin A gene FLNA as the culprit. In this case study, we present a 52-year-old female patient who sought medical care for recurring headaches and epilepsy. The present case emphasizes the necessity for ongoing study and exploration into the clinical trajectory and imaging of uncommon correlations between nodular heterotopia and mega cisterna magna.

X-linked neuronal migration disorders: Gender differences and insights for genetic screening

Cortical development depends on neuronal migration of both excitatory and inhibitory interneurons. Neuronal migration disorders (NMDs) are conditions characterised by anatomical cortical defects leading to varying degrees of neurocognitive impairment, developmental delay and seizures. Refractory epilepsy affects 15 million people worldwide, and it is thought that cortical developmental disorders are responsible for 25% of childhood cases. However, little is known about the epidemiology of these disorders, nor are their aetiologies fully understood, though many are associated with sporadic genetic mutations. In this review, we aim to highlight X-linked NMDs including lissencephaly, periventricular nodular heterotopia and polymicrogyria because of their mostly familial inheritance pattern. We focus on the most prominent genes responsible: including DCX, ARX, FLNA, FMR1, L1CAM, SRPX2, DDX3X, NSHDL, CUL4B and OFD1, outlining what is known about their prevalence among NMDs, and the underlying pathophysiology. X-linked disorders are important to recognise clinically, as females often have milder phenotypes. Consequently, there is a greater chance they survive to reproductive age and risk passing the mutations down. Effective genetic screening is important to prevent and treat these conditions, and for this, we need to know gene mutations and have a clear understanding of the function of the genes involved. This review summarises the knowledge base and provides clear direction for future work by both scientists and clinicians alike.

Stereo-EEG Evaluation and Surgical Treatment in Patients With Drug-Resistant Focal Epilepsy Associated With Nodular Heterotopia

PURPOSE

Nodular heterotopia (NH) is a common cause of drug-resistant epilepsy. Only limited studies detail the treatment of NH with laser interstitial thermal therapy and none analyze the relation between epileptogenicity and NH location.

METHODS

We retrospectively studied nine patients with drug-resistant epilepsy and NH who underwent stereoelectroencephalography and subsequent epilepsy surgery. Nodular heterotopia in the frontal lobes or along the bodies of the lateral ventricles was classified as anterior NH. Nodular heterotopia in the trigones, temporal or occipital horns, or temporal lobes was classified as posterior NH. Nodular heterotopia in both anterior and posterior locations was classified as diffuse NH. Interictal and ictal stereoelectroencephalography were analyzed, and patients were followed postoperatively to assess outcomes.

RESULTS

Of the six patients who underwent nine laser interstitial thermal therapy procedures either in isolation or in combination with other surgical therapies, four patients were Engel Ia, one was Engel IIb, and one was Engel IIIa, with an average follow-up of 22.8 months. All patients with posterior NH had interictal epileptiform abnormalities and seizures originating from the posterior NH. None of the patients with anterior NH had epileptiform activity recorded from their NH.

CONCLUSION

Laser interstitial thermal therapy alone or in combination with other surgical therapies is an effective treatment in those with drug-resistant epilepsy because of NH, even in those with extensive NH and broad seizure onset. We observed a trend suggesting that posterior NH are more likely to be epileptogenic compared with anterior NH and recommend that in patients with anterior NH, alternative epilepsy etiologies and stereoelectroencephalography implantation strategies be considered.

The analysis of 18 F-FDG PET/MRI, electroencephalography, and semiology in patients with gray matter heterotopia: A pilot study

OBJECTIVES

To describe ¹⁸ F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (¹⁸ F-FDG PET/MRI) along with semiology and electroencephalography (EEG) in patients with gray matter heterotopia (GMH); to evaluate the concordance between ¹⁸ F-FDG PET/MRI and clinical epileptogenic zone (EZ).

MATERIALS & METHODS

GMH (subcortical heterotopia [SCH] and periventricular nodular heterotopia [PNH]) patients with epilepsy who underwent ¹⁸ F-FDG PET/MRI were retrospectively enrolled. Two radiologists evaluated brain MRI, while two nuclear medicine specialists assessed the ¹⁸ F-FDG PET. The SUVmax values of visually hypometabolic cortical areas were compared to the contralateral cortex using a SUVmax threshold value of 10%; the SUVmax values of GMH lesions were compared with that of the right precentral gyrus. The cortex or GMH with hypometabolism on ¹⁸ F-FDG PET/MRI was considered representative of the EZ. The clinical EZ was identified using EEG and semiology.

RESULTS

Thirty patients (19 PNH; 11 SCH) with a mean age of 28.46 ± 9.52 years were enrolled. The heterotopic nodules were ametabolic in 3 patients (10%), hypometabolic in 16 (33.33%), isometabolic in 13 (26.66%), and hypermetabolic in 4 (10%). ¹⁸ F-FDG PET/MRI demonstrated hypometabolism in the cortex and GMH in 22/30 (73.33%) and 16/30 (53.33%). We could identify a clinical EZ in 18 patients, and 15 out of 18 (83.33%) had concordant ¹⁸ F-FDG PET/MRI findings.

CONCLUSION

Heterotopic nodules in GMH patients show different metabolic patterns on ¹⁸ F-FDG PET/MRI, with nearly three-quarters of the patients having cortical hypometabolism. ¹⁸ F-FDG PET/ MRI findings are mostly concordant with the clinical EZ.

Long-term Outcome of Epilepsy and Cortical Malformations Due to Abnormal Migration and Postmigrational Development: A Cohort Study

OBJECTIVE

To evaluate the long-term outcome of patients with epilepsy and malformations of cortical development (MCD).

METHODS

We conducted a historical cohort study of patients with epilepsy and MCD due to impaired neuronal migration and postmigration organization, and with a follow-up period of ≥5 years. For each patient, MCD was classified after accurate neuroimaging reappraisal by an expert neuroradiologist. The primary outcome was remission, defined as a period of seizure freedom ≥5 years at any time from epilepsy onset. We used Kaplan-Meier estimates for survival analysis, and univariate and multivariate Cox regression analyses to evaluate baseline variables as possible factors associated with remission.

RESULTS

The cohort included 71 patients (M/F=31/40) with a 17-year median follow-up (1506 person-years). About half (49.3%) had heterotopia, 35.2% polymicrogyria, 7% lissencephaly and 8.5% had the combination of two MCD. The mean age at seizure onset was 12.4±7.2 years. Intellectual disability and neurological deficits were observed in 30.4% and 40.9%, respectively. More than 60% of patients had refractory epilepsy. In three patients who underwent epilepsy surgery, MCD diagnosis was confirmed by histology. At last visit, 44% of patients had been seizure-free during the previous year, however none of them had stopped anti-seizure medication. Thirty patients achieved remission (Remission group, 42.2%) at some point in their disease history, whereas 41 individuals (Non Remission group, 57.8%) had never been in remission for ≥5 years. The cumulative remission rate was 38% by 20 years from inclusion. In the Cox model, unilateral distribution of MCD (HR: 2.68, 95% CI: 1.04-6.92) and a low seizure frequency at onset (HR: 5.01, 95% CI: 1.12-22.5) were significantly associated with remission.

CONCLUSIONS

Patients with epilepsy and MCD showed a remission rate of 38% by 20 years from onset. Unilateral distribution of the MCD is associated with a three-fold probability of achieving remission. About 40% of patients showed a drug-sensitive condition with risk of relapse during their epilepsy course.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that in patients with epilepsy and MCD, unilateral MCD and low seizure frequency at onset are associated with achieving epilepsy remission.

Neuroimaging of Childhood Epilepsy: Focal versus Generalized Epilepsy

Neuroimaging plays an increasingly crucial role in delineating the pathophysiology, and guiding the evaluation, management and monitoring of epilepsy. Imaging contributes to adequately categorizing seizure/epilepsy types in complex clinical situations by demonstrating anatomical and functional changes associated with seizure activity. This article reviews the current status of multimodality neuroimaging in the pediatric population, including focal lesions which may result in focal epileptic findings, focal structural abnormalities that may manifest as generalized epileptiform discharges, and generalized epilepsy without evidence of detectable focal abnormalities.

Fetal magnetic resonance imaging: supratentorial brain malformations

Fetal MRI is the modality of choice to study supratentorial brain malformations. To accurately interpret the MRI, the radiologist needs to understand the normal sequence of events that occurs during prenatal brain development; this includes familiarity with the processes of hemispheric cleavage, formation of interhemispheric commissures, neuro-glial proliferation and migration, and cortical folding. Disruption of these processes results in malformations observed on fetal MRI including holoprosencephaly, callosal agenesis, heterotopic gray matter, lissencephaly and other malformations of cortical development (focal cortical dysplasia, polymicrogyria). The radiologist should also be familiar with findings that have high association with specific conditions affecting the central nervous system or other organ systems. This review summarizes and illustrates common patterns of supratentorial brain malformations and emphasizes aspects that are important to patient care.

Whole-brain multimodal MRI phenotyping of periventricular nodular heterotopia

OBJECTIVE

To test the hypothesis that in periventricular nodular heterotopia (PVNH) structure and function of cortical areas overlying the heterotopic gray matter are preferentially affected.

METHODS

We studied a group of 40 patients with PVNH and normal-appearing cortex and compared their quantitative MRI markers of brain development, structure, and function to those of 43 age- and sex-matched healthy controls. Inspired by models of neocortical development suggesting that neuronal migration follows a curvilinear path to preserve topologic correspondence between the outer ventricular zone and the cortical surface, we computationally defined the overlying cortex using the Laplace equation and generated synthetic streamlines that link the ventricles, where nodules are located, and the neocortex.

RESULTS

We found multilobar cortical thickening encompassing prefrontal, latero-basal temporal, and temporoparietal cortices largely corresponding with the PVNH group-averaged map of the overlying cortex, the latter colocalized with areas of abnormal function, as defined by resting-state fMRI. Patients also presented hippocampal functional hyperconnectivity and malrotation, the latter positively correlating with neocortical maldevelopment indexed by increased folding complexity of the parahippocampus. In clusters of thickness and curvature findings, there were no significant differences between unilateral and bilateral PVNH; contrasting brain-wide metrics between cohorts was also unrevealing. There was no relationship between imaging markers and disease duration except for positive correlation with functional anomalies.

CONCLUSION

Our quantitative image analysis demonstrates widespread structural and functional alterations in PVNH with differential interaction with the overlying cortex and the hippocampus. Right hemispheric predominance may be explained by an early insult, likely genetically determined, on brain morphogenesis.

Agenesis of the corpus callosum with interhemispheric cyst: clinical implications and outcome

We describe two cases of agenesis of the corpus callosum (ACC) with interhemispheric cyst (IHC). Case 1: a male infant was born at 36 weeks gestation with a history of second trimester fetal ultrasound (US) scan and MRI showing ACC with IHC. His head circumference at birth and 5 months was at 90th centile. He developed infantile spasm and electroencephalogram showed hypsarrhythmia at 5 months of age. Seizures were controlled. He is under evaluation for surgical treatment. Case 2: ACC with a midline cyst was reported in the midtrimester US scan of a male infant. Subsequent fetal scans showed increasing size of the cyst. At birth, he had macrocephaly with a head circumference above 97th centile. MRI of the brain confirmed ACC with IHC. The parents refused a cystoperitoneal shunt offered. The child displayed gross neurodevelopmental delay with progressive hydrocephalus on follow-up and succumbed to aspiration pneumonia at 22 months of age.

Prenatally diagnosed periventricular nodular heterotopia: Further delineation of the imaging phenotype and outcome

OBJECTIVES

Periventricular nodular heterotopia (PNH) is a malformation of cortical development which presents with heterogeneous imaging, neurological phenotype and outcome. There is a paucity of comprehensive description detailing the prenatal diagnosis of PNH. The aim of this study is to report neuroimaging features and correlated outcomes in order to delineate the spectrum of prenatally diagnosed PNH.

METHODS

It was a retrospective study over 15 years in five tertiary centers. All fetuses with prenatally diagnosed PNH were collected. Fetal ultrasound and MRI were reviewed and genetic screening collected. Prenatal findings were analyzed in correlation to fetopathological analyses and post-natal follow up.

RESULTS

Thirty fetuses (22 females and 8 males) with PNH were identified. The two major ultrasound signs were ventriculomegaly associated with dysmorphic frontal horns (60%) and posterior fossa anomalies (73.3%). On MRI, two groups of PNH were identified: the contiguous and diffuse PNH (n = 15, 50%), often associated with megacisterna magna, and the non-diffuse, either anterior, posterior or unilateral PNH. FLNA mutations were found in 6/11 cases with diffuse PNH. Additional cortical malformations were exclusively observed in non diffuse PNH (9/15; 60%). Twenty-four pregnancies (80%) were terminated. Six children aged 6 months to 5 years are alive. Five have normal neurodevelopment (all had diffuse PNH) whereas one case with non diffuse PNH has developmental delay and epilepsy.

CONCLUSION

PNH is heterogeneous but patients with diffuse PNH are a common subgroup with specific findings on prenatal imaging and implications for prenatal counseling.

Germline and somatic mutations in cortical malformations: Molecular defects in Argentinean patients with neuronal migration disorders

Neuronal migration disorders are a clinically and genetically heterogeneous group of malformations of cortical development, frequently responsible for severe disability. Despite the increasing knowledge of the molecular mechanisms underlying this group of diseases, their genetic diagnosis remains unattainable in a high proportion of cases. Here, we present the results of 38 patients with lissencephaly, periventricular heterotopia and subcortical band heterotopia from Argentina. We performed Sanger and Next Generation Sequencing (NGS) of DCX, FLNA and ARX and searched for copy number variations by MLPA in PAFAH1B1, DCX, POMT1, and POMGNT1. Additionally, somatic mosaicism at 5% or higher was investigated by means of targeted high coverage NGS of DCX, ARX, and PAFAH1B1. Our approach had a diagnostic yield of 36%. Pathogenic or likely pathogenic variants were identified in 14 patients, including 10 germline (five novel) and 4 somatic mutations in FLNA, DCX, ARX and PAFAH1B1 genes. This study represents the largest series of patients comprehensively characterized in our population. Our findings reinforce the importance of somatic mutations in the pathophysiology and diagnosis of neuronal migration disorders and contribute to expand their phenotype-genotype correlations.

Sporadic periventricular nodular heterotopia: Classification, phenotype and correlation with Filamin A mutations

OBJECTIVE

The purpose of this study was to better delineate the clinical spectrum of periventricular nodular heterotopia (PNH) in a large patient population after long term follow up. Specifically, this study aimed to relate PNH subtypes to clinical or epileptic outcomes, epileptic discharges and underlying Filamin A (FLNA) mutations by analyzing anatomical features.

METHODS

The study included 100 patients with radiologically confirmed nodular heterotopia. Patients' FLNA gene sequences and medical records were analyzed. Two-sided Chi-square test and Fisher's exact t-test were used to assess associations between the distribution of PNHs and specific clinical features.

RESULTS

Based on imaging data, patients were subdivided into three groups: (a) classical (bilateral frontal and body, n=41 patients), (b) bilateral asymmetrical or posterior (n=16) and (c) unilateral heterotopia (n=43). Most patients with classical heterotopia were females (P=0.033) and were likely to have arachnoid cysts (P=0.025) and cardiac abnormalities (P=0.041), but were mostly seizure-free. Additionally, hippocampal abnormalities (P=0.022), neurological deficits (P=0.028) and cerebellar abnormalities (P=0.005) were more common in patients with bilateral asymmetrical heterotopia. Patients with unilateral heterotopia were prone to develop refractory epilepsy (P=0.041). FLNA mutations were identified in 8 patients.

CONCLUSIONS

Each group's distinctive genetic mutations, epileptic discharge patterns and overall clinical outcomes confirm that the proposed classification system is reliable. These findings could not only be an indicator of a more severe morphological and clinical phenotype, but could also have clinical implications with respect to the epilepsy management and optimization of therapeutic options.

Evaluation of Subependymal Gray Matter Heterotopias on Fetal MRI

BACKGROUND AND PURPOSE

Subependymal grey matter heterotopias are seen in a high proportion of children with Chiari II malformation and are potentially clinically relevant. However, despite its growing use, there is little in the literature describing its detection on fetal MRI. Our aim was to evaluate the accuracy in diagnosing subependymal gray matter heterotopias in fetuses with spinal dysraphism on fetal MR imaging.

MATERIALS AND METHODS

This study is a retrospective analysis of 203 fetal MRIs performed at a single institution for spinal dysraphism during a 10-year period. Corresponding obstetric sonography, postnatal imaging, and clinical/operative reports were reviewed.

RESULTS

Of the fetal MRIs reviewed, 95 fetuses were included in our analysis; 23.2% (22/95) were suspected of having subependymal gray matter heterotopias on fetal MR imaging prospectively. However, only 50% (11/22) of these cases were confirmed on postnatal brain MR imaging. On postnatal brain MR imaging, 28.4% (27/95) demonstrated imaging findings consistent with subependymal gray matter heterotopia. Only 40.7% (11/27) of these cases were prospectively diagnosed on fetal MR imaging.

CONCLUSIONS

Fetal MR imaging is limited in its ability to identify subependymal gray matter heterotopias in fetuses with spinal dysraphism. It is believed that this limitation relates to a combination of factors, including artifacts from fetal motion, the very small size of fetal neuroanatomy, differences in imaging techniques, and, possibly, irregularity related to denudation of the ependyma/subependyma in the presence of spinal dysraphism and/or stretching of the germinal matrix in ventriculomegaly.

Massive obesity and hyperphagia in posterior bilateral periventricular heterotopias: case report

Background

Bilateral posterior periventricular nodular heterotopia PNH is a complex malformation of cortical development with imaging features distinguishing it from classic bilateral PNH associated with filamin (FLNA) mutations. It distinctively consists of variably sized nodules of neurons along the trigones and temporal or occipital horns of the lateral ventricles and spectrum of developmental disorders of the mid-/hindbrain. This association suggests that pPNH is part of a more diffuse process of posterior or infrasylvian brain developmental abnormalities other than just a disorder of neuronal migration.

Case presentation

This report describes the first case of an Italian young girl featuring pPNH and severe hyperphagic obesity. At the time of our first examination at age 3 years of age she was severely obese (body mass index, BMI 45.9 Kg/m²) and food-seeking behavior in the free-living situation was reported by the relatives. She showed normal linear growth and cognition, but mildly dysmorphic facial traits including deeply-set eyes, prominent zygomatic bones, downturned mouth corners and low-set ears. Over the years, the patient progressively developed further massive weight gain (at age 9 years, her BMI was 60.4 Kg/m²) and hyperphagia was confirmed by an ad libitum test meal. During follow-up, she presented limitations in walking capacity and in physical functioning due to the disabling obesity. On the basis of distinctive neuro-radiological findings pPNH was diagnosed, in absence of history of seizures.

Conclusion

The present case may contribute to the expansion of the phenotypic expressions of this distinctive complex malformation.

47 patients with FLNA associated periventricular nodular heterotopia

Background

Heterozygous loss of function mutations within the Filamin A gene in Xq28 are the most frequent cause of bilateral neuronal periventricular nodular heterotopia (PVNH). Most affected females are reported to initially present with difficult to treat seizures at variable age of onset. Psychomotor development and cognition may be normal or mildly to moderately impaired. Distinct associated extracerebral findings have been observed and may help to establish the diagnosis including patent ductus arteriosus Botalli, progressive dystrophic cardiac valve disease and aortic dissection, chronic obstructive lung disease or chronic constipation. Genotype-phenotype correlations could not yet be established.

Methods

Sanger sequencing and MLPA was performed for a large cohort of 47 patients with Filamin A associated PVNH (age range 1 to 65 years). For 34 patients more detailed clinical information was available from a structured questionnaire and medical charts on family history, development, epileptologic findings, neurological examination, cognition and associated clinical findings. Available detailed cerebral MR imaging was assessed for 20 patients.

Results

Thirty-nine different FLNA mutations were observed, they are mainly truncating (37/39) and distributed throughout the entire coding region. No obvious correlation between the number and extend of PVNH and the severity of the individual clinical manifestation was observed. 10 of the mutation carriers so far are without seizures at a median age of 19.7 years. 22 of 24 patients with available educational data were able to attend regular school and obtain professional education according to age.

Conclusions

We report the clinical and mutation spectrum as well as MR imaging for a large cohort of 47 patients with Filamin A associated PVNH including two adult males. Our data are reassuring in regard to psychomotor and cognitive development, which is within normal range for the majority of patients. However, a concerning median diagnostic latency of 17 to 20 years was noted between seizure onset and the genetic diagnosis, intensely delaying appropriate medical surveillance for potentially life threatening cardiovascular complications as well as genetic risk assessment and counseling prior to family planning for this X-linked dominant inherited disorder with high perinatal lethality in hemizygous males.

Brain imaging and genetic risk in the pediatric population, part 1: inherited metabolic diseases

In this article, the genotype-MR phenotype correlation of the most common or clinically important inherited metabolic diseases (IMD) in the pediatric population is reviewed. A nonsystematic search of the PubMed/Medline database of relevant studies about "genotype-phenotype correlation" in IMD was performed. Some MR phenotypes related to specific gene mutations were found, such as bilateral hypertrophy of inferior olives in patients harboring POLG and SURF1 mutations, and central lesions in the cervical spinal cord in patients with nonketotic hyperglycinemia harboring GLRX5 gene mutation.

Unilateral periventricular heterotopia and epilepsy in a girl with Ehlers-Danlos syndrome

Purpose

Ehlers–Danlos syndrome (EDS), comprising a variety of inherited connective tissue disorders, has already been described in association with various neurological features, particularly with epilepsy and periventricular heterotopia (PH). Until now, there are reports of only bilateral periventricular heterotopia associated with Ehlers–Danlos syndrome.

Methods and results

Here we describe a 1-year, 4-month-old female who came under our care in the Pediatric Emergency Room because of prolonged afebrile generalized seizures, whose clinical picture allowed us to suspect a diagnosis of Ehlers–Danlos syndrome. Neuroradiological investigations showed unilateral periventricular heterotopias, and genetic analyses confirmed the hypothesized diagnosis, identifying in particular a mutation in the COL5A1 gene. After starting anticonvulsant therapy, her seizures showed a good response with seizure control and she had a favorable long-term course.

Conclusion

To our knowledge, this is the first report of unilateral periventricular heterotopia associated with Ehlers–Danlos syndrome. We first hypothesized a mosaicism as the cause of both, a unilateral localization of the heterotopias and a favorable long-term course with good response to anticonvulsant therapy; however, intriguingly, we could not demonstrate a mosaicism as the genetic condition in our patient and the neuroradiological findings and the favorable clinical outcome still remain unexplained.

Malformations of cortical development and epilepsy

Malformations of cortical development (MCDs) are an important cause of epilepsy and an extremely interesting group of disorders from the perspective of brain development and its perturbations. Many new MCDs have been described in recent years as a result of improvements in imaging, genetic testing, and understanding of the effects of mutations on the ability of their protein products to correctly function within the molecular pathways by which the brain functions. In this review, most of the major MCDs are reviewed from a clinical, embryological, and genetic perspective. The most recent literature regarding clinical diagnosis, mechanisms of development, and future paths of research are discussed.

Quantitative assessment of corpus callosum morphology in periventricular nodular heterotopia

We investigated systematic differences in corpus callosum morphology in periventricular nodular heterotopia (PVNH). Differences in corpus callosum mid-sagittal area and subregional area changes were measured using an automated software-based method. Heterotopic gray matter deposits were automatically labeled and compared with corpus callosum changes. The spatial pattern of corpus callosum changes were interpreted in the context of the characteristic anterior-posterior development of the corpus callosum in healthy individuals. Individuals with periventricular nodular heterotopia were imaged at the Melbourne Brain Center or as part of the multi-site Epilepsy Phenome Genome project. Whole brain T1 weighted MRI was acquired in cases (n=48) and controls (n=663). The corpus callosum was segmented on the mid-sagittal plane using the software "yuki". Heterotopic gray matter and intracranial brain volume was measured using Freesurfer. Differences in corpus callosum area and subregional areas were assessed, as well as the relationship between corpus callosum area and heterotopic GM volume. The anterior-posterior distribution of corpus callosum changes and heterotopic GM nodules were quantified using a novel metric and compared with each other. Corpus callosum area was reduced by 14% in PVNH (p=1.59×10(-9)). The magnitude of the effect was least in the genu (7% reduction) and greatest in the isthmus and splenium (26% reduction). Individuals with higher heterotopic GM volume had a smaller corpus callosum. Heterotopic GM volume was highest in posterior brain regions, however there was no linear relationship between the anterior-posterior position of corpus callosum changes and PVNH nodules. Reduced corpus callosum area is strongly associated with PVNH, and is probably associated with abnormal brain development in this neurological disorder. The primarily posterior corpus callosum changes may inform our understanding of the etiology of PVNH. Our results suggest that interhemispheric pathways are affected in PVNH.

Periventricular nodular heterotopia and dystonia due to an ARFGEF2 mutation

BACKGROUND

Heterotopias are a neuronal migration disorder caused by extrinsic factors or by genetic mutations. When the location is periventricular, the most frequent genetic cause is the mutation in the "filamin A2 gene", which is X-linked. New genes for periventricular nodular heterotopia with an autosomal inheritance pattern have been recently discovered.

PATIENTS

We describe two siblings. The girl, who was prenatally diagnosed ventriculomegaly, had delayed development. At 6 months, she had no head control and variable muscle tone, alternating low axial tone with jerking movements. She became microcephalic. Magnetic resonance imaging at 12 months of age revealed enlarged lateral ventricles, periventricular nodular heterotopia, thin corpus callosum, a T2-hyperintensity of the putamen and the thalamus, and a loss of volume of lenticular nucleus. At 18 months, she developed sporadic myoclonic seizures that were well controlled with valproic acid. Her younger brother also developed progressive microcephaly and psychomotor delay by 6 months. He exhibited axial hypotonia with a prominent dystonic-athetoid component. Magnetic resonance imaging at 15 months of age revealed asymmetric ventriculomegaly plus diffuse nodules lining the temporal horns, a thin corpus callosum, and hyperintensity signal in putamens. He had no seizures.

RESULTS

Because of the association of microcephaly, developmental delay with dystonic movements, the imaging results, and the probable autosomal recessive inheritance pattern, genetic analysis was requested. This detected a homozygous nonsense mutation in ARFGEF2 gene, at the DNA level c.388C>T in exon 4.

CONCLUSIONS

The presence of dyskinetic movements in individuals with acquired microcephaly could be a manifestation of periventricular nodular heterotopia due to ARFGEF2 mutation.

Corpus callosum and epilepsies

Introduction.Corpus callosum (CC) is the largest forebrain commissure. Structural anomalies and accompanying clinical symptoms are not in the focus of neurologists, epileptologists or neurosurgeons.

Aim and method.Anatomy, embryological development, normal functions, structural abnormalities, additional malformations, clinical symptoms and seizure disorders with CC anomalies are reviewed from the literature.

Review.The detection of callosal anomalies increased rapidly with widespread use of brain imaging methods. Agenesis or dysgenesis of corpus callosum (AgCC) might be considered an accidental finding. Epileptic seizures occur in up to 89% of patients with AgCC. The causal relationship correctly is questioned. However, additional causative malformations of midline and/or telencephalic structures can be demonstrated in most seizure patients. The interruption of bilateral spread of seizure activities acts as the concept for callosotomy as epilepsy surgery. Indications are drug-resistant generalized, diffuse, or multifocal epilepsies. A resectable seizure onset zone should be excluded. Most treated patients are diagnosed as Lennox-Gastaut or Lennox-like syndrome.

Conclusions.In cases with callosal abnormalities and clinical symptoms additional malformations are frequently observed, especially with seizure disorders. Callosotomy is the most effective option against drop attacks. The method probably is underused. After callosotomy a circumscript seizure focus might be unveiled and a second step of resective epilepsy surgery can be successful.

Posterior fossa malformation associated with cerebral anomalies: genetic and imaging features

Many posterior fossa malformations are associated with other malformations particularly supratentorial ones, which tend to affect the prognosis of these patients. The role of the cerebellum in higher learning is just beginning to be understood, but it is obvious that cerebellar abnormalities may result in higher-cognition defects. Studies have demonstrated cerebellar abnormalities in patients with developmental encephalopathies, such as autism, mental retardation, and Rett syndrome. Disorders that affect cell life cycles and result in abnormal cell proliferation and abnormal cell migration disorders (hemimegalencephaly, dystroglicanopathy, lissencephaly, and gray matter heterotopia) can also be accompanied by posterior fossa malformations. In this article, we discuss hindbrain-midbrain malformations associated with developmental encephalopathies and with supratentorial brain abnormalities that result from abnormal cell proliferation and cell migration.