Search

In 2018, I was honored to receive the Bernard Sachs Award for a lifetime of work expanding knowledge of diverse neurodevelopmental disorders. Summarizing work over more than 30 years is difficult but is an opportunity to chronicle the dramatic changes in the medical and scientific world that have transformed the field of Child Neurology over this time, as reflected in my own work. Here I have chosen to highlight five broad themes of my research beginning with my interest in descriptive terms that drive wider understanding and my choice for the title of this review. From there I will go on to contrast the state of knowledge as I entered the field with the state of knowledge today for four human brain malformations–lissencephaly, megalencephaly, cerebellar malformations, and polymicrogyria. For all, the changes have been dramatic.

Objective We describe the case of a boy with a TUBA1A mutation presenting with microphthalmia and congenital cataracts in addition to microcephaly and severe brain malformation. Methods A boy presented in early infancy with microphthalmia, congenital cataracts, and microcephaly. His neurological course included severe hypotonia and drug-resistant epilepsy. Magnetic resonance imaging of the brain revealed a complex malformation that included agenesis of the corpus callosum, severely hypoplastic cerebellar vermis, mildly hypoplastic and dysplastic cerebellar hemispheres, mildly hypoplastic brainstem, mild posterior simplified cerebral gyral pattern, dysplastic basal ganglia and thalami, hypoplastic optic nerves, and absent olfactory bulbs. Results TUBA1A genetic testing was conducted and revealed a previously unreported heterozygous 808G>T missense mutation. Parental genetic testing was negative, indicating that the child's mutation was de novo . Conclusion The TUBA1A gene encodes tubulin alpha-1A, a protein with an important role in microtubule function and stability. Human mutations can result in a wide spectrum of brain malformations including lissencephaly, microlissencephaly, cerebellar hypoplasia, agenesis of the corpus callosum, pachygyria and polymicrogyria. Although TUBA1A is expressed in both developing brain and retinal tissue, there are no reported cases of TUBA1A mutations in association with major developmental ophthalmologic abnormalities.

Malformations of cortical development include a wide range of brain developmental anomalies that commonly lead to developmental delay and epilepsy. Lissencephaly and subcortical band heterotopia are major malformations of cortical development due to abnormal neuronal migration and several genes have been identified including ARX, DCX, LIS1, RELN, TUBA1A, and VLDLR. Traditionally, genetic testing for lissencephaly and subcortical band heterotopia has been done in the order of the probability of detection of mutation according to the radiologic features, but the success rate could be variable with this time-consuming approach. In this study we used whole-exome sequencing to identify mutations in a 5-year-old girl with lissencephaly spectrum with subcortical band heterotopia. After excluding lissencephaly-related genes, one deleterious mutation (NM_178153.2:c.665C > T, p.Thr222Ile) in the DCX gene was identified. Further Sanger sequencing validated the variant in the patient but not in both parents indicating a de novo mutation. The present report demonstrates that whole-exome sequencing may be a useful tool for the identification of mutations in patients with lissencephaly and subcortical band heterotopias as well as malformations of cortical development.

Lissencephaly is a disorder of neuronal migration resulting in abnormal cerebral cortical sulcation and gyration. Affected children present with microcephaly, developmental delay, and early-onset epileptic seizures. Recently, de novo missense mutations in the tubulin α-1A (TUBA1A) gene were identified as causing a distinctive radiologic phenotype comprising of posteriorly predominant lissencephaly with dysgenetic corpus callosum, cerebellar and brainstem hypoplasia, and more recently, polymicrogyria. We describe a 14-month-old girl with TUBA1A mutation-associated lissencephaly, and summarize the clinical and neuroradiologic findings of 19 cases in the literature.

This study investigates the clinical features of epilepsy in 20 patients with brain malformation. Epileptic seizures were recognized in 15 patients, 12 of whom had their first seizure by 1 year of age. Partial seizure was the initial seizure type in 10 patients. Epileptic seizures were controlled in only four patients. Patients with holoprosencephaly and lissencephaly had seizure onset by 3 months of age, resulting in the most severe neurologic outcome. Only two patients with porencephaly had epileptic seizures, and in one of those patients the seizures were well controlled. A wide variety of clinical features of epilepsy in patients with brain malformation was found. More immature anomalous brain lesions may be associated with an enhanced capacity of epilepsy and resultant refractory seizures.

Background Brain malformations represent a major cause of refractory seizures. Standardized protocols to treat status epilepticus of newborn are not available in the literature. Patient We present a case report of use of ketamine administered to a late preterm with Pierre Robin sequence, lissencephaly, polymicrogyria, and severe epilepsy. Results The infusion of ketamine permitted resolution of status epilepticus, cardiorespiratory stabilization, and improved parental care for 15 days. No significant side effects were noted. Conclusion In the literature there are few studies regarding the use of ketamine for refractory status epilepticus, and only in nine of these described the use of, ketamine in children (2 months-18 years). This is the first report to document the effective use of ketamine in the newborn with status epilepticus.

The association of septo-optic dysplasia and cortical dysplasia is described as septo-optic dysplasia-plus. Reports on patients with septo-optic dysplasia-plus have been rare. We describe a 4-year-old girl with septo-optic dysplasia-plus syndrome, characterized by septo-optic dysplasia with schizencephaly, pachygyria, and diabetes insipidus.

In this study, technetium-99 ((99)Tc)-hexamethylpropyleneamine-oxine single-photon emission computed tomography (SPECT) was performed on 13 children with classic lissencephaly (nine with epileptic seizures, four without seizures). Focal or multifocal hypoperfusions were observed in 12 patients. The hypoperfused areas observed on SPECT scanning did not correlate with the localization of agyric-pachygyric regions in all patients. The distribution of perfusion abnormalities by SPECT and the localization of agyria-pachygyria as detected by magnetic resonance imaging did not correlate strongly. All nine patients with seizures and three of the four patients without seizures had focal or multifocal cerebral blood flow abnormalities on the SPECT scans. The presence of brain perfusion abnormalities detected by SPECT and the occurrence of epileptic seizures did not have a significant relationship. These results suggest that the role of SPECT studies in classic lissencephaly is not clearly defined. More sophisticated methods are needed to clarify the correlation between structural and functional abnormalities of patients diagnosed with lissencephaly.

Miller-Dieker syndrome represents a microdeletion syndrome spanning the LIS1 locus at 17p13.3, the deletion of which leads to lissencephaly. A fluorescence in situ hybridization study using an LIS1 probe is considered the standard laboratory diagnostic method for Miller-Dieker syndrome. This report documents a Miller-Dieker syndrome patient who tested normal when a commercially available LIS1 fluorescence in situ hybridization study probe was used but was later demonstrated to have a partial deletion of the LIS1 locus. The present case exemplifies a major shortcoming of commercially available fluorescence in situ hybridization studies for the diagnosis of microdeletion syndromes such as Miller-Dieker syndrome: that is, relatively small deletion can potentially remain undetected.

The authors describe an 11-year-old male with severe mental retardation, hypotonia, and arthrogryposis, with both type I lissencephaly and a congenital peripheral neuropathy, probably hypomyelinating with axonal involvement. To the best of the authors' knowledge, this is the first report involving the co-occurrence of these two developmental disorders. A viral, metabolic, or nutritional insult acting throughout the period of migration and myelination or a contiguous gene linkage are possible explanations for this disorder.

An 8-year-old female was diagnosed with Miller-Dieker syndrome with typical facial presentation. Brain magnetic resonance imaging disclosed lissencephaly, and chromosome study revealed 17p13.3 deletion. She developed infantile spasms at an early age, and her seizures were poorly controlled by multiple antiepileptics. Recurrent urinary tract infections were diagnosed during routine out-patient department follow-up. Urodynamic study disclosed a neurogenic bladder. Spinal magnetic resonance imaging revealed a tethered cord resulting from tight filum terminale, and untethering surgery was performed. Four months after the surgery, repeated urine cultures indicated that she was free from the urinary tract infection. Urodynamic study after untethering surgery demonstrated improved compliance of the urinary bladder.

A 2-month-old girl presented for neurologic evaluation secondary to mild facial dysmorphism, feeding difficulties, and failure to thrive. She was born at 39 weeks gestation following an uncomplicated pregnancy and delivery, with a birth weight of 2155 grams (small for gestational age). Documented at physical examination were a large anterior fontanel, a prominent and wrinkled forehead, a wide nasal bridge, low-set ears, upturned nares, and a sacral dimple. Magnetic resonance imaging of the lumbosacral plexus was consistent with a low-lying conus and a tethered spinal cord. Cranial magnetic resonance imaging (Fig 1) showed complete absence of sulcation with a smooth brain surface consistent with classical (Type I) lissencephaly. Electroencephalography indicated low-amplitude background activity over the posterior head regions, also consistent with lissencephaly. Chromosomal analysis revealed a deletion of the terminal region of the short arm of chromosome 17 (17p13.3), which contains the LIS1 gene (HGNC gene symbol PAFAH1B1) gene (alias LIS1), consistent with Miller-Dieker syndrome. Parental chromosomal findings were normal, indicating a de novo deletion. Transthoracic echocardiography yielded normal findings. She developed problems with gastroesophageal reflux, aspiration, and partial complex seizures by 3 months of age. By 6 months of age, she was noted to have distended forehead veins, central hypotonia, global developmental delay, and clusters of seizures suggestive of infantile spasms. Electroencephalography indicated frequent multi

We investigated the clinical characteristics of children with continuous spike waves during slow-wave sleep syndrome and their treatment response to levetiracetam. Five boys and one girl, diagnosed with epilepsy with continuous spike waves during slow-wave sleep syndrome, were enrolled. Their clinical characteristics, including neuroimaging findings, were reviewed. The signs related to continuous spike waves during slow-wave sleep included increased seizure frequency (6/6), impaired responsiveness (3/6), and psychomotor regression (2/6). Magnetic resonance imaging disclosed lissencephaly in one patient, and porencephaly of the left hemisphere in another. The number of antiepileptic drugs before the use of levetiracetam was 0-4 (mean +/- SD, 2.3 +/- 1.5). Five of 6 children demonstrated a good response to levetiracetam, whereas 2 (40%) underwent a relapse of electrical status epilepticus during sleep pattern on electroencephalograms 4 and 5 months after clinical improvement. Both were 5 years old. The most common presenting sign in children with continuous spike waves during slow-wave sleep syndrome is increasing seizure frequency. Levetiracetam is effective in treating children with continuous spike waves during slow-wave sleep syndrome. However, the relapse rate of continuous spike waves during slow-wave sleep syndrome remains high in young children.

The brains of patients with lissencephaly were examined by peroxidase-antiperoxidase immunohistochemical staining of synaptophysin, myelin basic protein, and glial fibrillary acidic protein. In contrast to the normal cortical pattern, the cortex, with a smooth surface, demonstrated quite different staining patterns in the molecular, superficial cellular, sparsely cellular, and deep cellular layers. The molecular layer was abnormally positive with synaptophysin staining. The superficial cellular layer was also diffusely stained for synaptophysin; there was a positive reaction in the linearly arranged myelin sheaths. The sparsely cellular layer revealed less staining for synaptophysin, but was perivascularly positive for glial fibrillary acidic protein. In the deep cellular layer, synaptophysin staining had multiple neuronal columns and myelin basic protein-staining had a reticular pattern around neuronal columns. These results suggest that the sparsely cellular layer may correspond to the molecular layer and white matter in normal brain; neurons with forming myelin sheaths in the superficial cellular layer regularly penetrate the surface of the molecular layer, forming arrested cortical columns in the deep cellular layer.

Classical lissencephaly is a neuroblast migration disorder that occurs either as isolated lissencephaly sequence or in association with malformation syndromes, such as the Miller-Dieker syndrome. In this work, alterations of the LIS1 gene in patients diagnosed as having isolated lissencephaly sequence were investigated. Ten patients were evaluated for the following aspects: classical cytogenetics by karyotyping using solid staining and G-banding; molecular cytogenetics using fluorescent in situ hybridization with a specific probe for the critical region of isolated lissencephaly sequence; and molecular analysis using deoxyribonucleic acid sequencing. Classical cytogenetic analysis indicated apparently normal karyotypes in all patients, but fluorescent in situ hybridization revealed a 17p13.3 microdeletion in one. In another patient, deoxyribonucleic acid sequencing disclosed a 1 base pair insertion in exon 4 within a sequence of eight consecutive adenine residues (162-163insA), a mutation that predicts a truncated protein. Two different polymorphisms were also detected: a T>C substitution in intron 6 (c.568 + 27bp T>C) and a C>T substitution in the nontranslated region of exon 11 (1250 C>T). These results indicate that cytogenetic analysis and molecular investigation of the LIS1 gene are not always sufficient to determine the disease etiology. These findings are consistent with previous studies and suggest the involvement of other genes in cortical malformation.

Hurler disease or syndrome is a disorder of mucopolysaccharide metabolism, inherited as an autosomal recessive trait. We describe a case of a 15-month-old female exhibiting with clinical and laboratory characteristics of the syndrome, central nervous system lesions (lissencephaly, excessive ventricular enlargement and Dandy Walker malformation with vermis atrophy, cerebellar cyst) and mongolian spots in the trunk and extremities. The combination of mongolian spots and severe central nervous system lesions in Hurler syndrome is considered a rare clinical occurrence, while the association with lissencephaly has never been reported.

To reveal the functional organization of the somatosensory area in the dysgenetic cortex, somatosensory-evoked potentials were examined in seven patients with congenital brain anomalies diagnosed by magnetic resonance imaging, including six patients in whom multichannel recordings over the scalp were used. In four patients with polymicrogyria/pachygyria and two with lissencephaly, the early cortical responses, frontal P20 and parietal N20, were absent in the cortex contralateral to the stimulated side. The first cortical response was a positive wave that appeared predominantly over the centroparietal area in five patients, and in the frontal area in the other patient with polymicrogyria/pachygyria. These findings suggest that the differentiated somatosensory function is distributed normally in the centroparietal cortex in most cases of widespread cortical dysplasia. However, the absence of P20/N20 may indicate a hypoplastic central sulcus or functionally undifferentiated subdivision of the somatosensory cortex in these patients. The absence of cortical responses in the patient with holoprosencephaly may correspond with growth failure of the thalamocortical afferent projections in this disorder.

Miller-Dieker syndrome (MDS) is a prototype of brain malformations characterized by abnormal neuronal migration. To clarify the pathomechanisms underlying these anomalies, we performed immunohistochemical studies using specific antibodies against the protein product of LIS-1, the candidate gene responsible for the MDS phenotype. The LIS-1 protein was present abundantly and ubiquitously in normally developing brains. Loss of LIS-1 immunoreactivity was observed in brains with MDS, but not in brains with other malformations, such as isolated lissencephaly, holoprosencephaly, Fukuyama-type congenital muscular dystrophy, and Zellweger syndrome. These results suggest that the pathomechanism underlying abnormal neuronal migration in MDS may be specific to this particular type of malformation.

Twenty-one neonates with subependymal cysts detected by neurosonography soon after birth were prospectively examined. The clinical and cranial sonographic findings were evaluated with respect to short-term prognosis. The prognosis was poor in 6 patients with congenital viral infection (4 with cytomegalovirus infection and 2 with rubella infection). Five patients also had neurodevelopmental abnormalities (2 with neonatal epileptic seizures, 2 with chromosomal abnormalities, and 1 with lissencephaly). The remaining 10 patients had normal psychomotor development. The incidence of congenital viral infection was statistically correlated with a poor neurodevelopmental outcome. A correlation did not exist between the short-term prognosis and each of the other clinical factors or cranial sonographic findings. Our evidence suggests that further investigation of possible subependymal cyst etiologies is required during a careful, long-term follow-up period.