Frontal Focal Cortical Dysplasia Research Articles

Cortical and subcortical morphometric changes in patients with frontal focal cortical dysplasia type II

Cortical and subcortical morphometric changes in patients with frontal focal cortical dysplasia type II

Brain network analysis of interictal epileptiform discharges from ECoG to identify epileptogenic zone in pediatric patients with epilepsy and focal cortical dysplasia type II: A retrospective study.

ObjectiveFor patients with drug–resistant focal epilepsy, intracranial monitoring remains the gold standard for surgical intervention. Focal cortical dysplasia (FCD) is the most common cause of pharmacoresistant focal epilepsy in pediatric patients who usually develop seizures in early childhood. Timely removal of the epileptogenic zone (EZ) is necessary to achieve lasting seizure freedom and favorable developmental and cognitive outcomes to improve the quality of life. We applied brain network analysis to investigate potential biomarkers for the diagnosis of EZ that will aid in the resection for pediatric focal epilepsy patients with FCD type II.MethodsTen pediatric patients with focal epilepsy diagnosed as FCD type II and that had a follow–up after resection surgery (Engel class I [n = 9] and Engel class II [n = 1]) were retrospectively included. Time–frequency analysis of phase transfer entropy, graph theory analysis, and power spectrum compensation were combined to calculate brain network parameters based on interictal epileptiform discharges from ECoG.ResultsClustering coefficient, local efficiency, node out–degree, and node out–strength with higher values are the most reliable biomarkers for the delineation of EZ, and the differences between EZ and margin zone (MZ), and EZ and normal zone (NZ) were significant (p < 0.05; Mann–Whitney U-test, two–tailed). In particular, the difference between MZ and NZ was significant for patients with frontal FCD (MZ > NZ; p < 0.05) but was not significant for patients with extra–frontal FCD.ConclusionsBrain network analysis, based on the combination of time–frequency analysis of phase transfer entropy, graph theory analysis, and power spectrum compensation, can aid in the diagnosis of EZ for pediatric focal epilepsy patients with FCD type II.

Small Lesion Size Is Associated with Sleep-Related Epilepsy in Focal Cortical Dysplasia Type II.

To investigate the neuroimaging and clinical features associated with sleep-related epilepsy (SRE) in patients with focal cortical dysplasia (FCD) type II. Patients with histopathologically proven FCD type II were included from three epilepsy centers. SRE was defined according to the video EEG findings and seizure history. Cortical surface reconstruction and volume calculation were performed using FreeSurfer. The lesions were manually delineated on T1 volumetric MRI using the ITK-SNAP software. The lesion volumes were normalized by the intracranial volume of each patient. The lesions were classified as small or large by placing a threshold based on quantitative (whether the lesion was detected on MRI report) and qualitative (volume) criteria. A total of 77 consecutive patients were included. Of them, 36 had SRE and 41 had non-SRE. An earlier age of epilepsy onset, high seizure frequency, regional interictal EEG findings, and favorable surgical outcome were characteristic in both groups. Small lesions were defined as those having a volume <3,217 mm3. In total, 60.9% of the patients with SRE (25/41) had small FCD lesion, which was significantly higher than the non-SRE group (9/34, 26.5%, p = 0.005). Small lesion size was the only predictor significantly associated with SRE in the overall type II group by multivariate analyses (p = 0.016). Although the proportion of patients who had frontal FCD and SRE was higher than non-frontal FCD (54.5 vs. 27.3%, p = 0.043), the relationship between SRE and lesion location was not confirmed by multivariate analysis. Thalamic volume and seizure semiology were not statistically different between the SRE and non-SRE group. The significant association between lesion size and SRE was reproducible in type IIb and IIa subgroups. SRE is common in patients with FCD type II. Small FCD type II lesions are significantly associated with SRE. Although our findings cannot be applied to the entire spectrum of SRE, potential existence of small FCD lesions should be considered when evaluating patients with SRE, and utilization of all other supportive electroclinical information for lesion detection is highly desirable.

Characteristics of EEG Seizure-Onset Patterns Recorded From Subdural Electrodes Over MRI-Visible Frontal Focal Cortical Dysplasia Type IIb Lesions.

Focal cortical dysplasia (FCD) is intrinsically epileptogenic, and an MRI-visible lesion typically constitutes the core part of the epileptogenic zone. We aimed to identify ictal EEG patterns that represent the epileptogenic zone by using subdural electrodes placed over the MRI-visible FCD lesion. We selected seven patients with frontal lobe epilepsy caused by pathologically proven FCD type IIb who underwent preoperative intracranial EEG evaluation with subdural electrodes followed by resection surgery with seizure-free outcome. The characteristics of ictal EEG patterns, interictal/ictal high-frequency oscillations, and ictal direct current shifts from intracranial electrodes placed over the MRI-visible lesion were analyzed. Two seizure-onset patterns (low voltage fast activity and fast spike activity) were identified. Low voltage fast activity was seen in all patients with a lateral frontal lesion, and it was always preceded by preictal spikes. Fast spike activity occurred only in patients with a mesial frontal lesion. Interictal/ictal high-frequency oscillations and ictal direct current shifts were seen in all patients. The epileptogenic zone of frontal FCD type IIb may be characterized by EEG seizure-onset patterns consisting of low voltage fast activity and fast spike activity accompanied by ictal high-frequency oscillations and ictal direct current shifts. Further study is needed to determine whether other seizure-onset patterns exist in patients with FCD type IIb.

Zoomed MRI Guided by Combined EEG/MEG Source Analysis: A Multimodal Approach for Optimizing Presurgical Epilepsy Work-up and its Application in a Multi-focal Epilepsy Patient Case Study

In recent years, the use of source analysis based on electroencephalography (EEG) and magnetoencephalography (MEG) has gained considerable attention in presurgical epilepsy diagnosis. However, in many cases the source analysis alone is not used to tailor surgery unless the findings are confirmed by lesions, such as, e.g., cortical malformations in MRI. For many patients, the histology of tissue resected from MRI negative epilepsy shows small lesions, which indicates the need for more sensitive MR sequences. In this paper, we describe a technique to maximize the synergy between combined EEG/MEG (EMEG) source analysis and high resolution MRI. The procedure has three main steps: (1) construction of a detailed and calibrated finite element head model that considers the variation of individual skull conductivities and white matter anisotropy, (2) EMEG source analysis performed on averaged interictal epileptic discharges (IED), (3) high resolution (0.5 mm) zoomed MR imaging, limited to small areas centered at the EMEG source locations. The proposed new diagnosis procedure was then applied in a particularly challenging case of an epilepsy patient: EMEG analysis at the peak of the IED coincided with a right frontal focal cortical dysplasia (FCD), which had been detected at standard 1 mm resolution MRI. Of higher interest, zoomed MR imaging (applying parallel transmission, ‘ZOOMit’) guided by EMEG at the spike onset revealed a second, fairly subtle, FCD in the left fronto-central region. The evaluation revealed that this second FCD, which had not been detectable with standard 1 mm resolution, was the trigger of the seizures.

Focal seizures versus epileptic spasms in children with focal cortical dysplasia and epilepsy onset in the first year

Focal cortical dysplasia (FCD) has been recognized as one of the most frequent causes of drug resistant epilepsy, especially in children. In infancy, onset of FCD-related epilepsy is substantially characterized by epileptic spasms (ES) or focal seizures. Which elements pertaining to the FCD are responsible for the onset of one type of seizure over the other is still unclear. Purpose of our study was to compare the characteristics of FCDs in terms of lateralization and site in patients with epileptic spasms versus patients with focal seizures. We retrospectively reviewed data from 41 patients with FCD related epilepsy with onset during the first 14 months of life. Seizure semeiology and drug resistance were analyzed, as were age at onset and FCD site and lateralization. Twenty-one children had focal seizures, 11 had ES and nine had focal seizures followed by ES. Mean age at onset was respectively 8.2, 5.1 and 1.8 months. Drug resistance was present in respectively 38.5%, 34.6% and 26.9% of children. Among patients with only ES, 90.9% had an exclusively frontal FCD localization, versus 42.9% of patients with focal seizures and 11.1% of patients with focal seizures followed by ES. FCD lateralization was right sided respectively in 47.6%, 81.8% and 66.7% of patients. Frontal lobe localization of FCDs was closely associated with ES (p=0.001). Moreover we also found that patients with focal seizures followed by ES had a significantly earlier age at onset compared to patients with focal seizures only (p<0.001). The association between ES and right-sided FCD lateralization, even if numerically suggestive, did not reach statistical significance (p=0.16). There was no significant association between seizure type and drug resistance (p=0.08).

Value of video electroencephalogram and magnetoencephalography in diagnosing and localizing image-negative frontal focal cortical dysplasia

Value of video electroencephalogram and magnetoencephalography in diagnosing and localizing image-negative frontal focal cortical dysplasia

Mystery Case: Cowden syndrome presenting with partial epilepsy related to focal cortical dysplasia

A 55-year-old man presented with seizures characterized by "tightening" of the right side and variable loss of awareness. EEG showed focal epileptogenic abnormalities over left and midline central regions. MRI showed left frontal focal cortical dysplasia (figure 1). He had multiple skin lesions (figure 2) and colonoscopy revealed gastrointestinal mucosal ganglioneuromas. Genetic testing of PTEN gene confirmed a diagnosis of Cowden syndrome (CS).

Epileptic monocular nystagmus and ictal diplopia as cortical and subcortical dysfunction.

We present the case of a patient with ictal monocular nystagmus and ictal diplopia who became seizure-free after resection of a right frontal focal cortical dysplasia (FCD), type 2B. Interictal neuroophthalmological examination showed several beats of a monocular nystagmus and a spasm of the contralateral eye. An exclusively ictal monocular epileptic nystagmus could be an argument for an exclusively cortical involvement in monocular eye movement control. The interictal findings in our patient, however, argue for an irregular ictal activation of both the cortical frontal eye field and the brainstem.

Clinical profile of patients with nascent alcohol related seizures

Aim:The aim of this study is to characterize the clinical profile of patients with alcohol related seizures (ARS) and to identify the prevalence of idiopathic generalized epilepsy (IGE) in the same.Materials and Methods:100 consecutive male patients presenting to a tertiary care center in South India with new onset ARS were analyzed with alcohol use disorders identification test (AUDIT) score. All underwent 19 channel digital scalp electroencephalography (EEG) and at least computed tomography (CT) scan.Results:A total of 27 patients (27%) who had cortical atrophy on CT had a mean duration of alcohol intake of 23.62 years compared with 14.55 years in patients with no cortical atrophy (P < 0.001). Twenty-two patients (22%) had clustering in the current episode of whom 18 had cortical atrophy. Nearly, 88% patients had generalized tonic clonic seizures while 12% who had partial seizures underwent magnetic resonance imaging (MRI), which identified frontal focal cortical dysplasia in one. Mean lifetime duration of alcohol intake in patients presenting with seizures within 6 hours (6H-gp) of intake of alcohol was significantly lower (P = 0.029). One patient in the 6H-gp with no withdrawal symptoms had EEG evidence for IGE and had a lower AUDIT score compared with the rest.Conclusion:CT evidence of cortical atrophy is related to the duration of alcohol intake and portends an increased risk for clustering. Partial seizures can be a presenting feature of ARS and those patients may benefit from MRI to identify underlying symptomatic localization related epilepsy (8.3% of partial seizures). IGE is more likely in patients presenting with ARS within first 6 hours especially if they do not have alcohol withdrawal symptoms and scalp EEG is helpful to identify this small subgroup (~1%) who may require long-term anti-epileptic medication.

Alteraciones de la migración neuronal: una causa de epilepsia farmacorresistente curable

Focal cortical dysplasia is a neuronal migration disorder that appears with bouts of epileptic seizures that are usually medication resistant. The improvements introduced into neuroimaging techniques in recent years have made it possible to diagnose and offer surgical treatment to certain patients who have been under polytherapy for many years with poor control over their seizures. We report the case of a 22-year-old male with epileptic fits since the age of 18 months, who was refractory to multiple combinations of oral antiepileptic drugs (AEDs) with electroencephalograms that displayed frontal, fast spike-wave discharges, with greater expression on the left side and findings from neuroimaging techniques that were repeatedly normal. After being readmitted to hospital because his seizures had got worse, the neuroimaging study was repeated and left frontal focal cortical dysplasia was observed, which led us to start considering neurosurgery. At present, six months after the intervention, the patient has had no further convulsive fits and therapy with oral AEDs is being reduced. Neuroimaging studies must be repeated in patients that have already been examined because in this way it may be possible to save a group of patients (who would otherwise have to resign to poor control over their seizures as well as the side effects of many AEDs) from becoming medication resistant.

Atypical case of hemiconvulsions‐hemiplegia‐epilepsy syndrome revealing contralateral focal cortical dysplasia

Hemiconvulsions‐hemiplegia‐epilepsy syndrome (HH/HHE) is a rare epileptic syndrome consisting of a prolonged unilateral convulsion producing a persisting hemiplegia, sometimes followed by epilepsy. We report on a 13‐month‐old male who presented with febrile left‐sided HH syndrome with right hemispheric unilateral cytotoxic oedema followed by hemispheric atrophy on magnetic resonance imaging (MRI). Six months later the child progressively developed refractory focal epilepsy, including right hemiclonic seizures, and nearly continuous left frontal rhythmic spikes, suggesting the presence of a focal cortical dysplasia (FCD). A repeat MRI at 2 years of age showed left frontal FCD. This unusual case of dual pathology ‐ right HH syndrome and left FCD ‐ suggests that some other factor than the malformation determined the prolonged status and brain atrophy. The kinetics of regional cortical maturation could explain this unusual condition.

Atypical case of hemiconvulsions-hemiplegia-epilepsy syndrome revealing contralateral focal cortical dysplasia

Hemiconvulsions-hemiplegia-epilepsy syndrome (HH/HHE) is a rare epileptic syndrome consisting of a prolonged unilateral convulsion producing a persisting hemiplegia, sometimes followed by epilepsy. We report on a 13-month-old male who presented with febrile left-sided HH syndrome with right hemispheric unilateral cytotoxic oedema followed by hemispheric atrophy on magnetic resonance imaging (MRI). Six months later the child progressively developed refractory focal epilepsy, including right hemiclonic seizures, and nearly continuous left frontal rhythmic spikes, suggesting the presence of a focal cortical dysplasia (FCD). A repeat MRI at 2 years of age showed left frontal FCD. This unusual case of dual pathology--right HH syndrome and left FCD--suggests that some other factor than the malformation determined the prolonged status and brain atrophy. The kinetics of regional cortical maturation could explain this unusual condition.