Marie-Odile Livet

EPILEPSY AND FOCAL GYRAL ANOMALIES DETECTED BY MRI: ELECTROCLINICO-MORPHOLOGICAL CORRELATIONS AND FOLLOW-UP

The authors studied 10 patients (mean age 15 years 6 months) with localized developmental gyral disorder detected by MRI. There were two groups of major malformations. Seven patients (group 1) had unilateral ‘macrogyric‐like’ insulo‐opercular changes, one of whom died early in life and had extensive microgyria. The six others had mental retardation and epilepsy, three of whom had focal neurological signs. Age at onset of epilepsy varied greatly. Clinical arid EEG data suggested a wider cerebral involvement than recognized on MRI. The remaining three patients (group 2) had abnormal gyri of variable topography and extension, with bulging grey matter and ventricular deformity. One had mental retardation, another had neurological signs. All had intractable complex partial seizures and focal EEG anomalies correlating with the MRI lesion site, pointing to a well‐defined epileptogenic zone. No clinical or EEG evidence of significant malformation in the remaining brain tissue was observed. Ablative surgery was beneficial for one patient; focal cortical dysplasia was the pathological substrate.

Mechanisms for variable expressivity of inherited SCN1A mutations causing Dravet syndrome

Background Mutations in SCN1A can cause genetic epilepsy with febrile seizures plus (GEFS+, inherited missense mutations) or Dravet syndrome (DS, de novo mutations of all types). Although the mutational spectra are distinct, these disorders share major features and 10% of DS patients have an inherited SCN1A mutation. Objectives and patients 19 selected families with at least one DS patient were studied to describe the mechanisms accounting for inherited SCN1A mutations in DS. The mutation identified in the DS probands was searched in available parents and relatives and quantified in the blood cells of the transmitting parent using quantitative allele specific assays. Results Mosaicism in the blood cells of the transmitting parent was demonstrated in 12 cases and suspected in another case. The proportion of mutated allele in the blood varied from 0.04–85%. In the six remaining families, six novel missense mutations were associated with autosomal dominant variable GEFS+ phenotypes including DS as the more severe clinical picture. Conclusion The results indicate that mosaicism is found in at least 7% of families with DS. In the remaining cases (6/19, 32%), the patients were part of multiplex GEFS+ families and seemed to represent the extreme end of the GEFS+ clinical spectrum. In this latter case, additional genetic or environmental factors likely modulate the severity of the expression of the mutation.

Neurological findings and seizure outcome in children with bilateral opercular macrogyric-like changes detected by MRI.

The authors studied 10 patients aged between six and 23 years (mean age 14 years 5 months) with magnetic resonance imaging, which detected bilateral ‘macrogyric‐like’ maldevelopment of the insulo‐opercular regions. The data confirm that biopercular gyral anomaly, associated with mental retardation, pseudobulbar palsy (cortical or central) and epilepsy, represents an anatomo‐clinical syndrome. Nevertheless, a wide clinical spectrum was found varying from pictures correlating with the topography and extent of the MRI‐detected anomaly to conditions indicating wider cerebral involvement. Epilepsy, varying greatly in age at onset and severity, consistently influenced the prognosis for five patients with diffuse EEG abnormalities and intractable seizures with falls. Anterior callosotomy relieved such seizures in one case.

Transient Brain Magnetic Resonance Imaging Hyperintensity in Basal Ganglia and Brain Stem of Epileptic Infants Treated With Vigabatrin

Vigabatrin is an antiepileptic drug that produces intramyelinic edema in several animal models. This study investigates the effect of vigabatrin on the developing human brain. The authors retrospectively blindly review 34 brain magnetic resonance imaging of 22 epileptic infants (age: 9 ± 1 months) that received vigabatrin, focusing on the presence of hyperintensity on T2- and diffusion-weighted images. Patients treated with vigabatrin displayed significant magnetic resonance imaging hyperintensity of basal ganglia and brain stem (P < .001, Wilcoxon test). This hyperintensity was transient and maximal 3 to 6 months after the beginning of vigabatrin. Hyperintensity was independent from duration and type of epilepsy, and from the presence or absence of seizures. The authors conclude that vigabatrin treatment is associated with transient hypersignal of the basal ganglia and brain stem in epileptic infants. Such transient hyperintensity is likely to be age-dependent and time-dependent because it has never been observed in adult patients.

Retard mental et phénotypes comportementaux

La notion de phenotype comportemental est maintenant bien admise, c’est une realite clinique indiscutable. Il s’agit d’un ensemble de comportements incluant processus cognitifs et interactions sociales qui est associe de facon significative a un syndrome genetique. Le point essentiel est que certains comportements sont assez caracteristiques pour faire evoquer immediatement le diagnostic de plusieurs syndromes neurogenetiques. L’interet clinique des phenotypes comportementaux est donc indiscutable pour le diagnostic, la prise en charge precoce des enfants ainsi que le soutien familial. Ils doivent etre bien connus des pediatres et des professionnels concernes.

Épilepsies de l’enfant : quelles informations pour l’enseignant ?

Les enfants epileptiques rencontrent souvent d’importantes difficultes a l’ecole : ils ont encore des restrictions excessives du fait des peurs multiples attachees a l’epilepsie et d’autre part ils ont souvent des difficultes d’apprentissage scolaire et de comportement, d’origine complexe. L’enseignant peut jouer un role tres important pour favoriser leur scolarisation, a condition d’etre suffisamment informe sur l’epilepsie et sur les crises propres a l’enfant ainsi que sur ses difficultes cognitives specifiques. Ce travail d’information fait partie du role du medecin avec l’accord des parents et en lien avec les differents partenaires.