The Use of Magnetic Resonance Spectroscopy in the Evaluation of Pediatric Patients With Seizures

BackgroundThe objective was to determine if it is useful to routinely add magnetic resonance spectroscopy (MRS) to magnetic resonance imaging (MRI) in the evaluation of seizure in the pediatric patient. Specifically, how often does MRS contribute information to conventional MRI?MethodsA retrospective search, over a period of 3 years, of patients <18 years of age who underwent both MRI and MRS as part of the evaluation of seizures yielded a total of 233 cases in 216 patients. The medical records were reviewed to determine how many patients carried a diagnosis relevant to seizures. The MRIs and MRSs were reviewed by two neuroradiologists and an MR physicist/spectroscopist who determined by consensus in how many cases MRS contributed information regarding management, diagnosis, or prognosis, in addition to the findings on MRI alone.ResultsIn 100 of 233 cases (43%), MRS contributed information additional to MRI. In 40 cases, MRS contributed information relevant to patient management by prompting an evaluation for an underlying inborn error of metabolism. MRS contributed information relevant to diagnosis in 24 of 100 cases (e.g., neoplasm versus dysplasia). MRS contributed information relevant to prognosis in 36 cases (e.g., hypoxic-ischemic injury). MRS added more information in cases where the patients had a diagnosis relevant to seizure before imaging. Interestingly, in 25 cases where the MRI was normal, MRS was found to be abnormal, which prompted evaluation for an inborn error of metabolism.ConclusionsThese results suggest that MRS is a useful evaluation tool in addition to MRI for children undergoing imaging for the evaluation of seizures.     

Clinical and Surgical Factors Associated With Increased Epilepsy Risk in Children With Hydrocephalus

BackgroundChildren with hydrocephalus are at risk for epilepsy both due to their underlying condition and as a consequence of surgical treatment; however, the relative contributions of these factors remain unknown.ObjectiveThe authors sought to characterize epilepsy among children with infancy-onset hydrocephalus and to examine the risks of epilepsy associated with hydrocephalus subtype and with factors related to surgical treatment.MethodsWe conducted a longitudinal cohort study of all children with infancy-onset hydrocephalus treated at a major regional children's hospital during 2002 to 2012, with follow-up to ascertain risk factors and epilepsy outcome through April 2015. Poisson regression was used to calculate adjusted risk ratios and 95% confidence intervals for associations.ResultsAmong 379 children with hydrocephalus, 86 (23%) developed epilepsy (mean onset age = 2.7 years), almost one fifth of whom had a history of infantile spasms. Relative to spina bifida–associated hydrocephalus, children with other major hydrocephalus subtypes had fourfold higher risks of developing epilepsy. Among children who underwent surgery, surgical infection doubled the risk of epilepsy (risk ratio = 2.0, 95% confidence interval = 1.4 to 3.0). Epilepsy was associated with surgical failure for intracranial reasons but not extracranial reasons (risk ratio = 1.7, 95% confidence interval = 1.1 to 2.7; risk ratio = 1.1, 95% confidence interval = 0.7 to 1.9, respectively).ConclusionsEpilepsy is common among children with hydrocephalus. Compared with children with spina bifida–associated hydrocephalus, children with other major hydrocephalus subtypes have a markedly increased risk of epilepsy. Surgical infection doubles the risk of epilepsy.     

Predictors of Cognitive Functions in Children With Sturge–Weber Syndrome: A Longitudinal Study

BackgroundSturge–Weber syndrome is often accompanied by seizures and neurocognitive deterioration, although previous studies have suggested that early functional brain reorganization may diminish the cognitive sequelae in some children with unilateral Sturge–Weber syndrome. The “rules” governing these plasticity mechanisms are poorly understood. In this study, we evaluated longitudinal changes of cognitive functioning (intelligence quotient [IQ]) and assessed the performance of clinical, electroencephalography (EEG), and magnetic resonance imaging (MRI) variables for predicting IQ in children with Sturge–Weber syndrome.MethodsThirty-three young children (mean age: 3.3 years at baseline) with unilateral Sturge–Weber syndrome underwent MRI, scalp EEG, and neuropsychology evaluation twice, with a median follow-up of 2 years. None of the children had epilepsy surgery. Longitudinal IQ changes were calculated. Seizure variables, interictal EEG abnormalities, and extent and location of MRI brain involvement were correlated with IQ assessed at follow-up.ResultsGlobal IQ showed a highly variable course with both increases and decreases over time. Lower IQ at baseline was associated with interval IQ increase. In univariate analyses, lower outcome IQ was associated with baseline EEG abnormalities (P < 0.001), young age at seizure onset (P = 0.001), high seizure frequency (P = 0.02), and early frontal-lobe involvement on MRI (P = 0.01). In multivariate analysis, EEG abnormalities at baseline remained a robust, independent predictor of outcome IQ.ConclusionsThe early trajectory of cognitive changes in children with unilateral Sturge–Weber syndrome is highly variable; children with improving IQ likely undergo effective unimpeded functional reorganization. Early onset, frequent seizures, and interictal epileptiform abnormalities on EEG likely interfere with this process resulting in poor cognitive functions. Future studies assessing interventions should target this high-risk subgroup to optimize cognitive outcome in Sturge–Weber syndrome.     

Predictive Factors for Epilepsy in Pediatric Patients With Sturge–Weber Syndrome

BackgroundSturge–Weber syndrome is characterized by a facial port-wine stain associated with either or both a retinal angioma and a cerebral pial angioma. Because a pial angioma may not be evident on the initial imaging studies, individuals at risk for epilepsy are often not identified before their first seizure. The aim of this study is to identify predictive factors predisposing Sturge–Weber patients to epilepsy.MethodsThe medical archives and photography database of our institution were reviewed to identify Sturge–Weber Syndrome patients followed up between 1990 and 2015. Patients without epilepsy were compared with patients with epilepsy based on the location of the port-wine stain, its extent and cerebral imaging.ResultsTwenty-four patients were included in the study. Thirteen did not develop epilepsy. Patients with bilateral port-wine stain were at higher risk of epilepsy (P = 0.03). Unilateral port-wine stain did not increase the risk of epilepsy (P = 0.29) regardless of its extent. The presence of developmental venous anomalies on brain imaging was also associated with a higher risk of epilepsy (P = 0.03).ConclusionsBilateral facial port-wine stain and cerebral developmental venous anomalies increase the risk of epilepsy in Sturge–Weber syndrome patients. Because they can be detected at birth, they might guide preventive management and follow-up.     

Anticonvulsant Efficacy in Sturge-Weber Syndrome

ObjectiveWe analyzed individuals with epilepsy due to Sturge-Weber syndrome to determine which anticonvulsants provided optimal seizure control and which resulted in the fewest side effects.MethodsOne-hundred-eight records from a single center were retrospectively analyzed for Sturge-Weber syndrome brain involvement, epilepsy, Sturge-Weber syndrome neuroscores, and currently used anticonvulsants.ResultsOf the fourteen anticonvulsants that had been employed, the most often used agents were oxcarbazepine or carbamazepine, and levetiracetam. Individuals whose seizures at the most recent visit were fully controlled (seizure-free) for 6 months or longer were more likely to have ever tried, or currently used, oxcarbazepine or carbamazepine than those with uncontrolled seizures. Thirty-nine of 69 individuals (56.5%) were seizure-free with oxcarbazepine or carbamazepine history versus 11 of 35 individuals (31.4%) who had not taken these agents (P < 0.05); 38 of 62 patients (61.3%) were seizure-free while currently taking these anticonvulsants versus 12 of 42 (28.6%) not taking them (P < 0.01). Patients with seizure control for 6 months or longer were less likely to have ever tried, or to currently be taking, levetiracetam than those without control. Sixteen of 56 individuals (28.6%) were seizure-free with levetiracetam history versus 34 of 48 (70.8%) without it (P < 0.001); 14 of 43 individuals (32.6%) were seizure-free and currently taking levetiracetam versus 36 of 61 (59.0%) not taking it (P < 0.01). When topiramate was added as second-line medication, five of nine patients (55.6%) experienced decreased seizure severity, and worsening of glaucoma was not reported.ConclusionsCarbamazepine and oxcarbazepine were associated with better seizure control than levetiracetam in this Sturge-Weber syndrome cohort and so may be preferred as the initial therapy. When used as adjunctive therapy, topiramate was effective in this limited analysis without a clear increased incidence of glaucoma.     

Clinical characteristics and post-surgical outcomes of focal cortical dysplasia subtypes

We retrospectively studied 105 patients with a focal cortical dysplasia (FCD) diagnosed on pathological examination, and investigated the long term postoperative seizure outcomes, different clinical characteristics of the three FCD subtypes, particularly type I and II, and surgical outcomes for each group. FCD is a common cause of drug-resistant epilepsy, which is divided into three different subtypes according to its involvement at different stages of brain development. Each of these groups may have different characteristics and may even have different surgical outcomes. After treatment, 55% of patients were completely seizure-free, with two significant predictive variables for poorer outcomes: focal MRI findings and electrode implantation. FCD type I had relatively poor surgical outcomes compared to FCD type II and type IIIa. Compared with FCD type I, type II, particularly IIb, had a higher frequency of seizure attacks, predominantly located in the extratemporal lobes, and was more readily detected and diagnosed via focal lesions on MRI and localized electroencephalogram abnormalities. FCD type II patients seem to show better surgical outcomes than FCD type I, but the difference was not significant. Larger cohort studies are needed for further evaluation of the seizure outcomes of different FCD subtypes.     

Intracranial EEG potentials estimated from MEG sources: A new approach to correlate MEG and iEEG data in epilepsy

Detection of epileptic spikes in MagnetoEncephaloGraphy (MEG) requires synchronized neuronal activity over a minimum of 4cm2. We previously validated the Maximum Entropy on the Mean (MEM) as a source localization able to recover the spatial extent of the epileptic spike generators. The purpose of this study was to evaluate quantitatively, using intracranial EEG (iEEG), the spatial extent recovered from MEG sources by estimating iEEG potentials generated by these MEG sources. We evaluated five patients with focal epilepsy who had a pre‐operative MEG acquisition and iEEG with MRI‐compatible electrodes. Individual MEG epileptic spikes were localized along the cortical surface segmented from a pre‐operative MRI, which was co‐registered with the MRI obtained with iEEG electrodes in place for identification of iEEG contacts. An iEEG forward model estimated the influence of every dipolar source of the cortical surface on each iEEG contact. This iEEG forward model was applied to MEG sources to estimate iEEG potentials that would have been generated by these sources. MEG‐estimated iEEG potentials were compared with measured iEEG potentials using four source localization methods: two variants of MEM and two standard methods equivalent to minimum norm and LORETA estimates. Our results demonstrated an excellent MEG/iEEG correspondence in the presumed focus for four out of five patients. In one patient, the deep generator identified in iEEG could not be localized in MEG. MEG‐estimated iEEG potentials is a promising method to evaluate which MEG sources could be retrieved and validated with iEEG data, providing accurate results especially when applied to MEM localizations. Hum Brain Mapp 37:1661–1683, 2016. © 2016 Wiley Periodicals, Inc .     

Automated alignment of perioperative MRI scans: A technical note and application in pediatric epilepsy surgery

Conventional image registration utilizing brain voxel information may be erroneous in a neurosurgical setting due to pathology and surgery‐related anatomical distortions. We report a novel application of an automated image registration procedure based on skull segmentation for magnetic resonance imaging (MRI) scans acquired before, during and after surgery (i.e., perioperative). The procedure was implemented to assist analysis of intraoperative brain shift in 11 pediatric epilepsy surgery cases, each of whom had up to five consecutive perioperative MRI scans. The procedure consisted of the following steps: (1) Skull segmentation using tissue classification tools. (2) Estimation of rigid body transformation between image pairs using registration driven by the skull segmentation. (3) Composition of transformations to provide transformations between each scan and a common space. The procedure was validated using locations of three types of reference structural landmarks: the skull pin sites, the eye positions, and the scalp skin surface, detected using the peak intensity gradient. The mean target registration error (TRE) scores by skull pin sites and scalp skin rendering were around 1 mm and <1 mm, respectively. Validation by eye position demonstrated >1 mm TRE scores, suggesting it is not a reliable reference landmark in surgical scenarios. Comparable registration accuracy was achieved between opened and closed skull scan pairs and closed and closed skull scan pairs. Our procedure offers a reliable registration framework for processing intrasubject time series perioperative MRI data, with potential of improving intraoperative MRI‐based image guidance in neurosurgical practice. Hum Brain Mapp 37:3530–3543, 2016. © 2016 Wiley Periodicals, Inc.