Neurosurgical management of medically intractable epilepsy associated with hypomelanosis of Ito

Megalencephaly syndromes associated with mutations of core components of the PI3K-AKT-MTOR pathway: PIK3CA, PIK3R2, AKT3, and MTOR

Megalencephaly (MEG) is a developmental abnormality of brain growth characterized by early onset, often progressive, brain overgrowth. Focal forms of megalencephaly associated with cortical dysplasia, such as hemimegalencephaly and focal cortical dysplasia, are common causes of focal intractable epilepsy in children. The increasing use of high throughput sequencing methods, including high depth sequencing to more accurately detect and quantify mosaic mutations, has allowed us to identify the molecular etiologies of many MEG syndromes, including most notably the PI3K-AKT-MTOR related MEG disorders. Thorough molecular and clinical characterization of affected individuals further allow us to derive preliminary genotype-phenotype correlations depending on the gene, mutation, level of mosaicism, and tissue distribution. Our review of published data on these disorders so far shows that mildly activating variants (that are typically constitutional or germline) are associated with diffuse megalencephaly with intellectual disability and/or autism spectrum disorder; moderately activating variants (that are typically high-level mosaic) are associated with megalencephaly with pigmentary abnormalities of the skin; and strongly activating variants (that are usually very low-level mosaic) are associated with focal brain malformations including hemimegalencephaly and focal cortical dysplasia. Accurate molecular diagnosis of these disorders is undoubtedly crucial to more optimally treat children with these disorders using PI3K-AKT-MTOR pathway inhibitors.

Hypomelanosis of Ito

Hypomelanosis of Ito, initially referred to as incontinentia pigmenti achromians, is a rare neurocutaneous disorder. Hypopigmented lesions following the lines of Blaschko are usually the presenting feature. Multiple organ systems can be involved including brain, musculoskeletal, cardiovascular, eyes, kidneys, and teeth. The neurologic complications can include seizures, hemimegalencephaly, developmental delay and abnormalities in tone. Genetic mosaicism is the most likely explanation for its inheritance. It must be distinguished from incontinentia pigmenti because at early stages, skin lesions can appear similar between the two conditions. Consensus recommendations for screening of associated extracutaneous conditions do not exist and management is symptomatic, but regular evaluation of somatic growth, neurodevelopment, endocrine status, eyes, and teeth should occur. Initial screening of renal function has also been recommended. Awareness of this disorder will allow for diagnosis, genetic counseling and appropriate screening.

Seizure outcomes in children with epilepsy after resective brain surgery

PURPOSE

To assess the role of resective brain surgery in childhood epilepsy.

METHODOLOGY

We retrospectively analysed the seizure outcomes in 55 children with epilepsy who had resective brain surgery between 1997 and 2012, at our centre. The children were 1.5-18 years at the time of surgery; their seizure onset was between 0.2 andto 15 years of age. 48 had refractory epilepsy. One child died of tumour progression. Follow-up duration in the survivors ranged from 2 to -16 years (mean: 9).Presurgical evaluation included clinical profiles, non-invasive V-EEG monitoring, neuroimaging with MRIs in all; SPECT and PET in selected patients. 54 had intraoperative ECoG.

RESULTS

An Engel Class 1 outcome was seen in 78% of the cohort, with 67% being off all AEDs at the most recent follow-up. Children with tumours constituted the majority (56%), with 87% of this group showing a Class 1 outcome and 84% being off AEDs. Children with cortical dysplasia had a Class 1 outcome in 56%.

CONCLUSION

Resective brain surgery is an efficacious option in some children with epilepsy. We found ECoG useful to tailor the cortical resection and in our opinion ECoG contributed to the good seizure outcomes.

Incontinentia pigmenti and hypomelanosis of Ito

Incontinentia pigmenti (IP) is a rare X-linked dominant neurocutaneous disorder affecting ectodermal tissue: skin, eyes, central nervous system, hair, nails, and teeth. It is usually lethal for males in utero. The involved gene is NEMO, an essential component of the nuclear factor-kappa B (NF-κB) signaling pathway. Skin lesions are highly diagnostic, occurring in neonates, with a particular distribution on Blaschko lines. The severity of the disease is related to ocular and neurological impairment. The hallmark of ocular IP is retinal vasculopathy including peripheral retinal vascular nonperfusion, macular infarction and neovascularization, and preretinal neovascularization. CNS involvement consists of seizures, mental retardation, hemiparesis, spasticity, microcephaly, cerebellar ataxia, and coma. It often occurs in neonates. Some patients have persistent pharmacoresistant seizures throughout life. MRI findings consist essentially in: white-matter lesions; scattered cortical neuronal necrosis; multiple cerebral infarctions; cerebral atrophy, hypoplasia of the corpus callosum, encephalomalacia and neuronal heterotopia. A predominant role of vascular occlusive phenomena in small vessels is highly suspected. In fact several intricate mechanisms could be discussed: vascular, inflammatory, developmental mechanisms. Their role and predictive factors of IP CNS involvement in neonatal IP need to be better understood to identify effective innovative therapies. Hypomelanosis of Ito can occur in the neonate, infancy, or childhood, be isolated or diffuse, often following the Blaschko lines, and can fade in childhood or adulthood. It is due to reduced melanin in the epidermis. Eye, central nervous (mental retardation, epilepsy, language disabilities, motor system dysfunction, psychiatric symptoms including autism - with frequent cortical malformations including hemimegalencephaly and white matter involvement), and musculoskeletal systems can also be affected. Mosaicism with various chromosomal rearrangements has been reported.

New association between ring chromosome 20 syndrome and hypomelanosis of Ito

Hypomelanosis of Ito is an uncommon neuroectodermal disease associated with a wide range of cytogenetic abnormalities. Ring chromosome 20 is a rare chromosomal disorder characterized by severe, refractory epilepsy, cognitive delay, and unspecific dysmorphic traits. An association between the hypomelanosis of Ito and ring chromosome 20 syndrome was never reported peviously. We describe a young girl who has ring chromosome 20 and who also has clinical symptoms of hypomelanosis of Ito. After her diagnosis of epilepsy, she was submitted to neurologic and genetic testing, a skin biopsy, and repeated neuropsychologic examinations. Karyotyping revealed a 46 XX, r(20) with mosaicism in 34% of peripheral blood lymphocytes and 8% of skin fibroblasts. A severe, progressive cognitive deterioration was evident. The epilepsy was refractory to antiepileptic drugs, in apparent contrast with the evidence that both telomeric regions were preserved. The percentage of mosaicism seems unrelated to the severity of the clinical phenotype.

Heterogeneous seizure manifestations in Hypomelanosis of Ito: report of four new cases and review of the literature

Hypomelanosis of Ito (HI) is a rare neuroectodermal disorder often associated with mental retardation and epilepsy. We report on four new HI patients presenting with heterogeneous seizure manifestations and we review the literature concerning epileptic seizures in HI. At one extreme, there are patients with generalized seizures well controlled by drug treatment, whereas at the opposite there are patients with severe, often pharmacoresistant, focal seizures. The genetic substrate for HI syndrome is not homogenous and only partially understood. Further researches are required to shed light on the pathogenesis of HI phenotypes.

Psychosis related to neurological conditions: pro and cons of the dis- / mis-connectivity models of schizophrenia

Schizophrenia is still a condition with obscure causes and psychopathology. This paper aims to discuss the “disconnectivity” hypothesis in relation to some neurological conditions which are known to alter brain connectivity, as well as mimicking some aspects of the disorder. After a short historical introduction to the concept, we will examine the evidence for connectivity problems in schizophrenia, separating the anatomical level from the functional level. Then, we will discuss three different issues concerning connectivity: i) local reduction in connectivity without neuronal loss (within the gray matter); ii) reduction in or alteration of long-range connectivity (within the white matter); and iii) abnormal targets for connections. For each of these aspects, we will look at the conditions able to reproduce anomalies capable of increasing susceptibility to schizophrenia. We conclude that psychosis is more likely to occur: i) when long-range connectivity is concerned; ii) when lesions result in lengthening and scattering of conduction times; and iii) when there are high dopamine levels, shedding light on or adding weight to the idea of an interaction between dopamine and connectivity.

Epilepsy surgery for the neurocutaneous disorders

Patients with neurophakomatoses were not always considered to be candidates for surgical resection of epileptogenic foci, given the multifocal nature of their disease. Advances in imaging, monitoring, and surgical technique have allowed the identification of particularly active areas of cortex that may provide these patients with better seizure control than medications alone. Options for surgical resection range from focal resections (in those with localized disease) to hemispherectomies (in those with hemispheric involvement).