Malformations cérébrales et épilepsie : présentations radiocliniques et implications pour le diagnostic génétique

Genetic and clinical variations of developmental epileptic encephalopathies

OBJECTIVE

The concept of 'developmental and epileptic encephalopathy (DEE)' recognises that in infants presenting with severe early-onset epilepsy, neurodevelopmental comorbidity may be attributable to both the underlying cause and to adverse effects of uncontrolled epileptic activity. There is no direct genotype - phenotype correlation in DEEs. This study aimed to report the genetic and phenotypic differences in patients with DEE.

METHODS

Genetic evaluations of the patients were performed due to epilepsy combined with developmental delay, epileptic encephalopathy, motor deficits, autistic features, or cognitive impairment. Patients were assessed for demographic characteristics, medical history, family history, psychomotor development, seizure control interventions, electroencephalogram (EEG) and magnetic resonance imaging (MRI) findings.

RESULTS

This study included 20 children aged 0-16 years who were diagnosed as having DEE.The types of DEE detected in our study were DEE 2, 4, 6B, 7, 11, 26, 30, 33, 35, 42, 58, 62, and 67.Status epilepticus was recorded in only DEE7. The most common EEG abnormality was multifocal epileptic discharges (35%,) followed by burst-suppression patterns in patients with neonatal-onset seizures. Thirteen of the children were aged over 2 years, two (15%) were non-ambulatory and six (46%) were non-verbal. MRI scans were normal in 80% of the patients. Refractory epilepsy seen in 33% of cases.De-novo mutation, microcephaly and dysmorphic findings accompany resistant seizures and are associated with poor prognosis.

DISCUSSION

For patients with movement disorders, developmental delay, autism, and ID with or without epilepsy in any period of their life, next-generation sequencing is the only diagnostic technique available, with genetic analysis often being the only diagnostic method.

Pregnancy denial and unplanned home delivery: Considerations about fetal death causes and maternal drug use imputability

Determining fetal death causes is a complex problem for the forensic pathologist. Beyond the medico-legal context, the expert must be able to evaluate the viability of the fetus at the time of death, to eliminate in-utero fetal death and to determine if the death is related to a fetal, a maternal, a placental cause, or simply related to obstetrical complications. The authors present the case of a 21-year-old woman who unexpectedly gave birth to a fetus during a party. As pregnancy was not acknowledged by the mother (regular menstrual cycles and use of hormonal contraception), no obstetrical check-up had been performed. She would have presented violent abdominal pain and expelled a mass in the toilet. The fetus body, enclosed in the amniotic pouch, and the placenta were found in the toilet. A forensic autopsy was performed jointly by a forensic pathologist and a specialist in fetal pathology. Histological, toxicological and genetic samples were collected. Body morphometry and bone maturation indicated a gestational age of 31-32 weeks of amenorrhea. A significant asphyxia syndrome and non-specific multi-visceral congestion were noted at autopsy. Histological analysis of the fetal tissues revealed a lung and skeletal muscle maturation in accordance with the estimated term. At the brain level, there were signs of anoxia and abnormal cortical development with periventricular nodular heterotopia areas. The placenta microscopic analysis revealed acute chorioamniotitis, the probable cause of the premature fetal expulsion. Toxicological analyses revealed the presence of ecstasy (48 ng/mL) and its metabolite MDA (2 ng/mL) in fetal blood. Although negative in blood, THC-COOH tested positive in urine (9 ng/mL). The fetus was repetitively exposed to cannabis, as Δ9-THC tested positive in hair (51 pg/mg). Maternal hair analysis on 4 × 3 cm evidenced a long-term use of cannabis, while results support single massive exposure to ecstasy. In this article, the authors try to explain the reflexive pathway carried out to establish death causes and the maternal toxic consumption imputability on the cerebral malformations and fetal death. This case illustrates both the interest of toxicological analyses in cases of fetal death and the importance of a collaborative work between forensic and fetal pathologists and toxicologists, which appeared critical to answer in the best conditions to the magistrates questions, as well as to the bereaved families.

X-linked ataxias

X-linked cerebellar ataxias (XLCA) are an expanding group of genetically heterogeneous and clinically variable conditions characterized by cerebellar dysgenesis (hypoplasia, atrophy, or dysplasia) caused by gene mutations or genomic imbalances on the X chromosome. The neurologic features of XLCA include hypotonia, developmental delay, intellectual disability, ataxia, and other cerebellar signs. Normal cognitive development has also been reported. Cerebellar defects may be isolated or associated with other brain malformations or extraneurologic involvement. More than 20 genes on the X chromosome, mainly encoding for proteins involved in brain development and synaptic function that have been constantly or occasionally associated with a pathologic cerebellar phenotype, and several families with X-linked inheritance have been reported. Given the excess of males with ataxia, this group of conditions is probably underestimated and families of patients with neuroradiologic and clinical evidence of a cerebellar disorder should be counseled for high risk of X-linked inheritance.

Malformations of cortical development and epilepsy in adult patients

OBJECTIVE

To describe clinical features of epilepsy secondary to Malformation of Cortical Development (MCD) in a series of adult patients.

MATERIALS AND METHODS

We searched our database for all cases with confirmed epilepsy and MCD and included in the study only those with complete data. Mean age, sex, age at seizure onset (ASO), seizure types, abnormal neurological exam (ANE), mental retardation, family history, gestational or perinatal insults (G-PI), interictal EEG and response to treatment were analyzed. Cases were classified into the 3 main groups (G) according to the Barkovich classification (BC) and then compared: (G1) "malformations due to abnormal cell proliferation", (G2) "malformations due to abnormal migration" and (G3) "malformations due to abnormal cortical organization".

RESULTS

We identified 152 (5.06%) patients with MCD from a total of 3000 with epilepsy. In total, 138 patients with complete medical data were included in this study. The mean age of patients was 36.2 years, 52.2% were female, the mean ASO was 12.3 years, 5.1% of cases had a positive family history and 21% had G-PI. An ANE was observed in 21% and mental retardation in 31.9%. Most of the patients (84.8%) had refractory epilepsy. The distribution of cases according to the BC was: 51.4% in G1, 28.9% in G2 and 19.6% in G3. Comparing the 3 groups, we found that an ANE was statistically more frequent in G3 and was present in 70.4% of cases.

CONCLUSION

Our series of adult patients with epilepsy and MCD suggests that MCD are identified as commonly in a developing country as in previous "first world" series. Neurological deficits were more common in the subgroup of patients with polymicrogyria and schizencephaly (BC Group 3).

X-linked disorders with cerebellar dysgenesis

X-linked disorders with cerebellar dysgenesis (XLCD) are a genetically heterogeneous and clinically variable group of disorders in which the hallmark is a cerebellar defect (hypoplasia, atrophy or dysplasia) visible on brain imaging, caused by gene mutations or genomic imbalances on the X-chromosome. The neurological features of XLCD include hypotonia, developmental delay, intellectual disability, ataxia and/or other cerebellar signs. Normal cognitive development has also been reported. Cerebellar dysgenesis may be isolated or associated with other brain malformations or multiorgan involvement. There are at least 15 genes on the X-chromosome that have been constantly or occasionally associated with a pathological cerebellar phenotype. 8 XLCD loci have been mapped and several families with X-linked inheritance have been reported. Recently, two recurrent duplication syndromes in Xq28 have been associated with cerebellar hypoplasia. Given the report of several forms of XLCD and the excess of males with ataxia, this group of conditions is probably underestimated and families of patients with neuroradiological and clinical evidence of a cerebellar disorder should be counseled for high risk of X-linked inheritance.

Bilateral perisylvian polymicrogyria with cerebellar dysplasia and ectopic neurohypophysis

Polymicrogyria (involving or not the sylvian scissure) with cerebellar cortical dysplasia or vermis hypoplasia has been reported in few cases. In addition, the association between ectopic neurohypophysis and other cortical malformations, including bilateral perisylvian polymicrogyria, has been documented. We describe a girl affected by focal epilepsy since the age of 2 years. Magnetic resonance imaging (MRI) at 11 and 22 years of age showed bilateral perisylvian polymicrogyria, dysplasia of the left cerebellar hemisphere, and ectopic neurohypophysis. Genetic tests, including fluorescent in situ hybridization 22q11.2 and array-comparative genomic hybridization, and pituitary hormones (at the age of 20 years) were normal. The patient is now 22 years old, and she is seizure free under therapy with lamotrigine and levetiracetam. To the best of our knowledge, this is the first description of this complex cerebral malformation. This finding confirms that bilateral perisylvian polymicrogyria can be associated with other cerebral malformations; cerebellum and neurohypophysis must be carefully evaluated in patients with polymicrogyria.