PRRT2 mutations in familial infantile seizures, paroxysmal dyskinesia, and hemiplegic migraine

Objective: To perform a clinical and genetic study of a family with benign familial infantile seizures (BFIS) and, upon finding a PRRT2 gene mutation, to study a cohort of probands with a similar phenotype. We extended the study to all available family members to find out whether PRRT2 mutations cosegregated with additional symptoms. Methods: We carried out a clinical and genealogic study of a 3-generation family and of 32 additional probands with BFIS (11 families), infantile convulsions and paroxysmal choreoathetosis (ICCA) (9 families), BFIS/generalized epilepsy with febrile seizures plus (5 families), and sporadic benign neonatal or infantile seizures (7 probands/families). We performed a genetic study consisting of linkage analysis and PRRT2 screening of the 33 probands/families. Results: We obtained a positive linkage in the 16p11.3-q23.1 chromosomal region in the large BFIS family. Mutation analysis of PRRT2 gene revealed a c.649dupC (p.Arg217Profs*8) in all affected individuals. PRRT2 analysis of the 32 additional probands showed mutations in 10, 8 familial and 2 sporadic, probands. Overall we found PRRT2 mutations in 11 probands with a mutation rate of 11 out of 33 (33%). BFIS co-occurred with migraine and febrile seizures in 2 families, with childhood absence epilepsy in one family and with hemiplegic migraine in one family. Conclusion: Our results confirm the predominant role of PRRT2 mutations in BFIS and expand the spectrum of PRRT2-associated phenotypes to include febrile seizures, childhood absence seizures, migraine, and hemiplegic migraine. Neurology  2012;79:2109–211

SYNGAP1-DEE: A visual sensitive epilepsy

International audienceObjective: To further delineate the electroclinical features of individuals with SYNGAP1 pathogenic variants.Methods: Participants with pathogenic SYNGAP1 variants and available video-electroencephalogram (EEG) recordings were recruited within five European epilepsy reference centers. We obtained molecular and clinical data, analyzed EEG recordings and archived video-EEGs of seizures and detailed characteristics of interictal and ictal EEG patterns for every patient.Results: We recruited 15 previously unreported patients and analyzed 72 EEGs. Two distinct EEG patterns emerged, both triggered by eye closure. Pattern 1 (14/15 individuals) consisted of rhythmic posterior/diffuse delta waves appearing with eye-closure and persisting until eye opening (strongly suggestive of fixation-off sensitivity). Pattern 2 (9/15 individuals) consisted of diffuse polyspike-and-wave discharges triggered by eye closure (eye-closure sensitivity). Both patterns presented in 8/15. Including archived video-EEG clips of seizures from 9/15 patients, we analyzed 254 seizures. Of 224 seizures experienced while awake, 161 (72%) occurred at or following eye closure. In 119/161, pattern 1 preceded an atypical absence, myoclonic seizure or myoclonic absence; in 42/161, pattern 2 was associated with eyelid myoclonia, absences and myoclonic or atonic seizures.Conclusions: Fixation-off and eye closure were the main triggers for seizures in this SYNGAP1 cohort.Significance: Combining these clinical and electroencephalographic features could help guide genetic diagnosis

Abnormal Spontaneous Blood Oxygenation Level Dependent Fluctuations in Children with Focal Cortical Dysplasias:Initial findings in surgically confirmed cases

Background  Focal cortical dysplasias (FCD) are a frequent cause of drug-resistant epilepsy in children but are often undetected on structural magnetic resonance imaging (MRI). We aimed to measure and validate the variation of resting state functional MRI (rs-fMRI) blood oxygenation level dependent (BOLD) metrics in surgically proven FCDs in children, to assess the potential yield for detecting and understanding these lesions. Methods  We prospectively included pediatric patients with surgically proven FCD with inconclusive structural MRI and healthy controls, who underwent a ten-minute rs-fMRI acquired at 3T. Rs-fMRI data was pre-processed and maps of values of regional homogeneity (ReHo), degree centrality (DC), amplitude of low frequency fluctuations (ALFF) and fractional ALFF (fALFF) were calculated. The variations of BOLD metrics within the to-be-resected areas were analyzed visually, and quantitatively using lateralization indices. BOLD metrics variations were also analyzed in fluorodeoxyglucose-positron emission tomography (FDG-PET) hypometabolic areas. Results  We included 7 patients (range: 3-15 years) and 6 aged-matched controls (range: 6-17 years). ReHo lateralization indices were positive in the to-be-resected areas in 4/7 patients, and in 6/7 patients in the additional PET hypometabolic areas. These indices were significantly higher compared to controls in 3/7 and 4/7 patients, respectively. Visual analysis revealed a good spatial correlation between high ReHo areas and MRI structural abnormalities (when present) or PET hypometabolic areas. No consistent variation was seen using DC, ALFF, or fALFF. Conclusion  Resting-state fMRI metrics, noticeably increase in ReHo, may have potential to help detect MRI-negative FCDs in combination with other morphological and functional techniques, used in clinical practice and epilepsy-surgery screening.</p

Complete hemispherotomy leads to lateralized functional organization and lower level of consciousness in the isolated hemisphere

International audienceObjectiveTo quantify whole-brain functional organization after complete hemispherotomy, characterizing unexplored plasticity pathways and the conscious level of the dissected hemispheres.MethodsEvaluation with multimodal magnetic resonance imaging in two pediatric patients undergoing right hemispherotomy including complete callosotomy with a perithalamic section. Regional cerebral blood flow and fMRI network connectivity assessed the functional integrity of both hemispheres after surgery. The level of consciousness was tested by means of a support vector machine classifier which compared the intrinsic organization of the dissected hemispheres with those of patients suffering from disorders of consciousness.ResultsAfter hemispherotomy, both patients showed typical daily functionality. We found no interhemispheric transfer of functional connectivity in either patient as predicted by the operation. The healthy left hemispheres displayed focal blood hyperperfusion in motor and limbic areas, with preserved network-level organization. Unexpectedly, the disconnected right hemispheres showed sustained network organization despite low regional cerebral blood flow. Subcortically, functional connectivity was increased in the left thalamo-cortical loop and between the cerebelli. One patient further showed unusual ipsilateral right cerebello-cortical connectivity, which was explained by the mediation of the vascular system. The healthy left hemisphere had higher probability to be classified as in a minimally conscious state compared to the isolated right hemisphere.SignificanceComplete hemispherotomy leads to a lateralized whole-brain organization, with the remaining hemisphere claiming most of the brain's energetic reserves supported by subcortical structures. Our results further underline the contribution of nonneuronal vascular signals on contralateral connectivity, shedding light on the nature of network organization in the isolated tissue. The disconnected hemisphere is characterized by a level of consciousness which is necessary but insufficient for conscious processing, paving the way for more specific inquiries about its role in awareness in the absence of behavioral output.Key PointComplete hemispherotomies are rare operations permitting the evaluation of functional processing in both hemispheres as compared to other surgical proceduresAfter hemispherotomy, no interhemispheric transfer was identified in two pediatric patients evaluated with multimodal MRICortical connectivity was lateralized, with preserved network organization in the defected right hemisphere despite hypoperfusionThalamo-cortical and cerebello-cortical connectivity was preserved in the healthy hemispheres; intercerebellar connectivity was unaffectedThe defected right hemisphere resembled less the conscious capacities of patients in minimally conscious stat

Posterior resection for childhood lesional epilepsy: neuropsychological evolution

The aim of this study was to provide information on the neuropsychological evolution of children with symptomatic epilepsy who have undergone surgical resection of posterior (occipitoparietal) lesions. Twelve children with epilepsy with parietal and/or occipital lesions were enrolled in the study and followed after surgical resection: full clinical and epileptic examinations were performed before and after surgery, as was a neuropsychological study of both general and specific cognitive abilities. Epilepsy evolution was generally good (Engel classification IA in nine cases) with persistent selective neurological impairments (eye field defects, sensory unilateral spatial neglect) in some cases, consistent with the lesion site. Neuropsychological defects before surgery in the absence of refractory epilepsy were minimal with a normal global cognitive competence; yet, the relatively low performance scores with some impairment of specific cognitive skills were strictly correlated with defects in visual perceptive skills in both right- and left-sided lesions. Surgery seems to have improved performance abilities, whereas other abnormal specific skills did not change with the exception of working memory that in some cases was defective before surgery and normalized after lesion removal. Our study in this particular cohort of children with epileptogenic occipitoparietal lesions thus confirmed a trend toward a benign epileptic and neurodevelopmental outcome after surgical resection of the lesion

Sleep-potentiated epileptiform activity in early thalamic injuries: Study in a large series (60 cases)

OBJECTIVE: The study aims at a better definition of continuous spike-waves during sleep (CSWS) with an early thalamic lesion, focusing on various grades of sleep-potentiated epileptiform activity (SPEA). Their possible relationship with different clinical features was studied to try to define prognostic factors of the epileptic disorder, especially relating to behavior/cognitive outcome, in order to improve prevention and treatment strategies. METHODS: Sixty patients with early thalamic injury were followed since the first registration of SPEA with serial neurological, long term EEG monitoring and neuropsychological examinations, as well as neuroimaging and a detailed clinical history. They were classified in three different groups according to the sleep spike-waves (SW) quantification: electrical status epilepticus during sleep (ESES), more than 85% of slow sleep; overactivation between 50% and 85% and simple activation between 10 and 50%). Results were then examined also with a statistical analysis. RESULTS: In our series of CSWS occurring in early brain injured children with unilateral thalamic involvement there is a common neuropathologic origin but with various grades of SPEA severity. Statistical analysis showed that patients evolving toward ESES presented more commonly the involvement of the mediodorsal part of thalamus nuclei and a bilateral cortico-subcortical brain injury, epilepsy was more severe with a delayed onset; moreover, in the acute stage .ESES patients presented the worst behavior/cognitive performances. As to cognitive and behavior outcome, longer SPEA duration as well as bilateral brain injury and cognitive/behavior impairment in acute phase appear linked to a poor outcome; some particular neuropathology (ischemic stroke and haemorrhagic infarction) as well as hydrocephalus shunting are associated with behavior disorders. CONCLUSIONS: Discrete features seem to support different underlying mechanisms in ESES patients in comparison with less severe SPEA; they represent negative prognostic factors. Longer SPEA duration as well as bilateral brain injury and cognitive/behavior impairment in acute phase seem predictive of a worse cognitive/behavior outcome