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.

An Independent Seizure-Onset Zone in Medial Temporal Lobe Found by 18 F-FDG PET Imaging Besides Epileptogenic Periventricular Nodular Heterotopia

ABSTRACT

A 23-year-old man with drug-resistant epilepsy was admitted for presurgical evaluation. The epileptogenic zone could not be derived from seizure semiology and scalp electroencephalographic monitoring definitely. MRI showed periventricular nodular heterotopia in occipital horn of left lateral ventricle with high FDG uptake on interictal 18 F-FDG PET scan, whereas the hypometabolic zone in the left medial temporal lobe was also found on PET with no abnormality on MRI. Stereoelectroencephalographic implantation was performed to identify the seizure-onset zone. Two independent epileptogenic foci located in periventricular nodular heterotopia and left hippocampus were validated by stereoelectroencephalographic monitoring and the outcome of subsequent thermocoagulation.

Phenotypic manifestations in FLNA-related periventricular nodular heterotopia: a case report and review of the literature

Periventricular nodular heterotopia (PVNH) is an X-linked disease caused by loss-of-function variants in the filamin A (FLNA) gene. FLNA-PVNH is a heterogeneous disorder, and the phenotype is associated with neurological and non-neurological features including cardiovascular, gastrointestinal, pulmonary, haematological, cutaneous and skeletal manifestations. No clear definition of the FLNA-PVNH phenotype has been established, but the patients are predominantly females with seizures, cardiovascular manifestations, and normal intelligence or mild intellectual disability. Herein, we describe a PVNH patient diagnosed with a novel heterozygous missense variant in FLNA after an atypical presentation of deep vein thrombosis and thrombocytopenia. Clinical evaluation found hypermobility, cardiovascular and skin manifestations. Moreover, we conducted a literature review of 186 FLNA-PVNH patients to describe the phenotypic spectrum. In conclusion, our patient highlights the importance of thorough clinical evaluation to identify manifestations in this very heterogeneous disorder. The phenotypic review may guide clinicians in the assessment and follow-up of FLNA-PVNH patients.

Three Different FDG Patterns in Periventricular Nodular Heterotopia Correlated to Video Stereoelectroencephalography

ABSTRACT

A 40-year-old woman with a drug-resistant focal epilepsy underwent cerebral FDG PET in phase 1 presurgical epilepsy study. MRI essentially showed multiple periventricular nodular heterotopias. The stereoelectroencephalography coupled to MRI and FDG PET helped to define the anatomofunctional correlation of the epileptogenic zone network. This procedure brought to light 3 distinct patterns of FDG consumption, corresponding to different anatomoelectroclinical features. This pattern was already found in a previous FDG PET reflecting a "stable" permanent intralesional intercritical stereoelectroencephalography activity, an electrical "signature" of the lesion. Finally, functional imaging improved thermocoagulation in this patient and emphasized the use of FDG in drug-resistant epilepsy.

Periventricular nodular heterotopia

BACKGROUND

Periventricular nodular heterotopia (PNH) is an embryonal neuronal migration disturbance of the brain. The condition is rare and genetically heterogeneous, often caused by mutations in the FLNA gene. The most common symptoms are epileptic seizures. PNH is often associated with other conditions such as cardiovascular abnormalities.

CASE PRESENTATION

A young man was admitted to hospital after a first episode of loss of consciousness. The patient was in normal general condition upon admission, and the clinical examination revealed no abnormalities. However, cerebral imaging performed upon admittance showed PNH, while an extended cardiac examination revealed atrioventricular block with the indication for a pacemaker. After pacemaker implantation and introduction of antiepileptic drug therapy, the patient has been free of symptoms.

INTERPRETATION

PNH is a condition that needs multidisciplinary assessments.

Reading deficits correlate with cortical and subcortical volume changes in a genetic migration disorder

Periventricular nodular heterotopia (PNH) is the most common type of epileptogenic neuronal migration disorder, and often presents with epilepsy and reading disability. The functional role of ectopic nodules has been widely studied. However, the associated structural cortical and subcortical volumetric alterations have not been well characterized. Moreover, it is unknown whether a correlation between volumetric changes and behavioral problems exists.40 subjects with bilateral PNH and 40 matched healthy controls were enrolled in this study. The total cerebral, gray matter, white matter, and cerebrospinal fluid (CSF) volumes were compared between the two groups. Furthermore, structural and functional correlations were evaluated between volumetric changes and reading disability.There were no significant differences detected in total cerebral, gray matter or CSF volumes between the two groups, but there was a significant trend of larger gray-matter volume in PNH. Specifically, smaller white matter volumes were found in the PNH patients. Moreover, the volume of white matter was negatively related to time in the digit rapid naming task and a similar but insignificant trend was seen between the volume of gray matter and backward digit span.These findings suggest that reading disability exists in our sample of bilateral PNH. Periventricular nodules would have normally migrated to the overlying cortex. However, the total cerebral, gray matter, and CSF volumes were unaffected. Alterations in neuronal migration may have an impact in the white matter associated reading dysfluency, that is, visually normal.

[Periventricular nodular heterotopia : a pediatric case]

Periventricular nodular heterotopia (PVNH) is a cerebral cortex malformation, due to a deletion/duplication in the FLNA gene, located on the chromosome X. The gene is coding a cytoskeleton protein. The transmission is dominant. It enters the heterogeneous group of philaminopathies. There is a feminine predominance. Males most often show early lethality. The clinical presentation is characterised by a seizure disorder ranging from mild to intractable, a mental retardation, hypotonia, cardiovascular abnormalities, vasculopathy and/or coagulopathy leading to stroke. The surveillance must be made by a pluridisciplinary team and the genetic counseling is necessary. We present here a paediatric case.

Phenotypic and imaging features of FLNA-negative patients with bilateral periventricular nodular heterotopia and epilepsy

PURPOSE

Periventricular nodular heterotopia (PVNH) is a malformation of cortical development due to impaired neuronal migration resulting in the formation of nodular masses of neurons and glial cells in close proximity to the ventricular walls. We report the clinical characteristics of the largest case series of FLNA-negative patients with seizures and bilateral periventricular heterotopia.

METHODS

Participants were recruited through the Epilepsy Phenome/Genome Project (EPGP), a multicenter collaborative effort to collect detailed phenotypic data and DNA on a large number of individuals with epilepsy, including a cohort with symptomatic epilepsy related to PVNH. Included subjects had epilepsy, and MRI confirmed bilateral PVNH. Magnetic resonance imaging studies were visually and quantitatively reviewed to investigate the topographic extent of PVNH, symmetry, and laterality.

KEY FINDINGS

We analyzed data on 71 patients with bilateral PVNH. The incidence of febrile seizures was 16.6%. There was at least one other family member with epilepsy in 36.9% of this population. Developmental delay was present in 21.8%. Focal onset seizures were the most common type of seizure presentation (79.3%). High heterotopia burden was strongly associated with female gender and trigonal nodular localization. There was no evidence for differences in brain volume between PVNH subjects and controls. No relationship was observed between heterotopic volume and gender, developmental delay, location of PVNH, ventricular or cerebellar abnormalities, laterality of seizure onset, age at seizure onset, and duration of epilepsy.

SIGNIFICANCE

A direct correlation was observed between high heterotopia burden, female gender, and trigonal location in this large cohort of FLNA-negative bilateral PVNH patients with epilepsy. Quantitative MRI measurements indicated that this correlation is based on the diffuse nature of the heterotopic nodules rather than on the total volume of abnormal heterotopic tissue.

Integration of gray matter nodules into functional cortical circuits in periventricular heterotopia

Alterations in neuronal circuitry are recognized as an important substrate of many neurological disorders, including epilepsy. Patients with the developmental brain malformation of periventricular nodular heterotopia (PNH) often have both seizures and dyslexia, and there is evidence to suggest that aberrant neuronal connectivity underlies both of these clinical features. We used task-based functional MRI (fMRI) to determine whether heterotopic nodules of gray matter in this condition are integrated into functional cortical circuits. Blood oxygenation level-dependent (BOLD) fMRI was acquired in eight participants with PNH during the performance of reading-related tasks. Evidence of neural activation within heterotopic gray matter was identified, and regions of cortical coactivation were then mapped systematically. Findings were correlated with resting-state functional connectivity results and with performance on the fMRI reading-related tasks. Six participants (75%) demonstrated activation within at least one region of gray matter heterotopia. Cortical areas directly overlying the heterotopia were usually coactivated (60%), as were areas known to have functional connectivity to the heterotopia in the task-free resting state (73%). Six of seven (86%) primary task contrasts resulted in heterotopia activation in at least one participant. Activation was most commonly seen during rapid naming of visual stimuli, a characteristic impairment in this patient population. Our findings represent a systematic demonstration that heterotopic gray matter can be metabolically coactivated in a neuronal migration disorder associated with epilepsy and dyslexia. Gray matter nodules were most commonly coactivated with the anatomically overlying cortex and other regions with resting-state connectivity to heterotopia. These results have broader implications for understanding the network pathogenesis of both seizures and reading disabilities.

Abnormal structural and functional brain connectivity in gray matter heterotopia

PURPOSE

Periventricular nodular heterotopia (PNH) is a malformation of cortical development associated with epilepsy and dyslexia. Evidence suggests that heterotopic gray matter can be functional in brain malformations and that connectivity abnormalities may be important in these disorders. We hypothesized that nodular heterotopia develop abnormal connections and systematically investigated the structural and functional connectivity of heterotopia in patients with PNH.

METHODS

Eleven patients were studied using diffusion tensor tractography and resting-state functional connectivity MRI with bold oxygenation level-dependent (BOLD) imaging. Fiber tracks with a terminus within heterotopic nodules were visualized to determine structural connectivity, and brain regions demonstrating resting-state functional correlations to heterotopic nodules were analyzed. Relationships between these connectivity results and measures of clinical epilepsy and cognitive disability were examined.

KEY FINDINGS

A majority of heterotopia (69%) showed structural connectivity to discrete regions of overlying cortex, and almost all (96%) showed functional connectivity to these regions (mean peak correlation coefficient 0.61). Heterotopia also demonstrated connectivity to regions of contralateral cortex, other heterotopic nodules, ipsilateral but nonoverlying cortex, and deep gray matter structures or the cerebellum. Patients with the longest durations of epilepsy had a higher degree of abnormal functional connectivity (p = 0.036).

SIGNIFICANCE

Most heterotopic nodules in PNH are structurally and functionally connected to overlying cortex, and the strength of abnormal connectivity is higher among patients with the longest duration of epilepsy. Along with prior evidence that cortico-cortical tract defects underlie dyslexia in this disorder, the current findings suggest that altered connectivity is likely a critical substrate for neurologic dysfunction in brain malformations.

Periventricular nodular heterotopia and cardiovascular defects

BACKGROUND

Periventricular nodular heterotopia (PNH) is a rare congenital anomaly of the brain presenting as nodular heterotopia along the paraventricular region. Ten cases of PNH complicated by aortic aneurysm have been reported in the literature, and 9 of them also had symptoms of Ehlers-Danlos syndrome (EDS). This study investigated the association of PNH and cardiovascular anomalies in Asians.

METHODS

Patients with a diagnosis of brain heterotopia on magnetic resonance imaging at Chang Gung Memorial Hospital between 1994 and 2010 were screened for both typical PNH and cardiovascular anomalies. The family members of the index cases were also evaluated.

RESULTS

One family (5 patients) and a sporadic case were found to have both typical PNH and cardiovascular anomalies. Two of them had aortic root aneurysm, one had aortic regurgitation, and one had minor valvular disease. Two patients had a history of seizures, but none of them had EDS.

CONCLUSIONS

Clinical heterogeneity exists in the patients with PNH. Overlap in the symptoms of PNH, cardiovascular anomalies, aortic aneurysm, and EDS were reviewed. EDS is unusual in Asians with PNH. Aortic aneurysm and other valvular heart diseases are common cardiovascular anomalies in PNH patients.