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Results for “Megalencephaly”

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8 recordsLinked to original sources
PubMed1978

Megalencephaly in infants and children. The possible role of increased dural sinus pressure.

Seven children studied because of clinical macrocephaly and suspected hydrocephalus ultimately proved to have megalencephaly apparently due to an increase in sagittal sinus venous pressure as established from infusion studies. Unexplainably, these patients were all males. All were seen initially between 2 and 8 months of age. Head enlargement exceeded two standard deviations in all seven. Pneumoencephalography, ventriculography, or computerized tomography demonstrated normal or minimally enlarged ventricles that did not progress in size. Isotope cisternography was abnormal. Studies of CSF formation and absorption demonstrated normal absorption rates but high calculated sagittal sinus pressures. Though therapy was usually not required, in one unusual infant, severe progressive macrocephaly with minimal hydrocephalus required a shunt. Another had a transient episode of acute hydrocephalus associated with a low CSF absorption rate and ventricular enlargement. In this report, we review the intracranial hydrodynamics of benign intracranial hypertension (BIH), communicating hydrocephalus, and the pathogenesis of megalencephaly. Benign intracranial hypertension and the type of megalencephaly demonstrated by our patients appear to develop similarly except that the presence of open cranial sutures may allow a transient nonhydrostatic loading of brain parenchyma in infants, resulting in mild, nonprogressive macrocephaly.

Brain↗
PubMed1978

Megalencephaly and chromosomal anomaly.

A 6-year-old mentally retarded boy died after cardiac surgery for Fallot's tetralogy. The brain was of enormous size, weighing 2230 grams and showing widespread polymicrogyria and dysdifferentiation to regular large pyramidal neurons without increased DNA content. Nuclear Barr bodies indicated a XXY-chromosomal (Klinefelter) syndrome, which has not been previously reported in megalencephaly. True megalencephaly (excluding the symptomatic forms) should remain a pathological diagnosis and restricted to cases with an abnormally high brain weight in addition to morphological alterations. There is evidence for a genetic base in many cases of megalencephaly, and chromosomal studies may yield more information in this respect

Autopsy↗
PubMed1978

The radiographic features of unilateral megalencephaly.

Unilateral megalencephaly is a rare anomaly of the brain which causes enlargement of a lobe or an entire hemisphere. The radiological features of the disease are a poorly defined unusual mass effect on PEG, angiography and CT scan. Pathologically, the disease is thought to be due to abnormal cell migration in the 3rd month in utero.

Brain↗
PubMed1979

Unilateral megalencephaly, cerebral cortical dysplasia, neuronal hypertrophy, and heterotopia: cytomorphometric, fluorometric cytochemical, and biochemical analyses.

A 13-month-old boy with intractable seizures, left hemiparesis, and psychomotor retardation due to right unilateral megalencephaly, died in hypovolemic shock 1 day after hemispherectomy. The gyral pattern of the hypermegalic hemisphere was simplified and coarse. The cortical cytoarchitecture was disarrayed by a population of giant neurons. Hippocampus and calcarine cortex were cytoarchitectonically normal, as was the entire left cerebral hemisphere. Neuronal heterotopias were present in the right centrum semiovale and both cerebellar hemispheres. Cytomorphometric study of parietal cortex of each cerebral hemisphere revealed a 4-fold increase in neuronal nuclear, and 11-fold increase in neuronal nucleolar, volume in the hypermegalic hemisphere, whereas glial nuclear volume was only one-third as great, in part because of edema of the left hemisphere. Microfluorometric cytochemical analysis demonstrated a 16% increase in neuronal DNA, 40% increase in total neuronal RNA, 12% increase in glial DNA, and 15% increase in glial RNA on the right. Biochemical analysis of tissue extracts disclosed increases in the right hemisphere of 40%, 56%, and 66%, respectively, for DNA, RNA, and protein. The data suggest heteroploidy of chromosomal DNA and enhanced transcription and translation in the hypermegalic hemisphere. Thus, a defect in regulation of cell metabolism may account for the morphologic and clinical abnormalities.

Brain↗
PubMed1979

Normal children with large heads--benign familial megalencephaly.

Fifteen normal children with large heads (circumference greater than 0.5 cm above the 98th centile) were studied. CAT scans were pefrormed to exclude hydrocephalus, and ventricular size was compared with that of hydrocephalic children. In 11 of the 13 families in which the parents' heads were measured, one parent (10 fathers and one mother) was found to have a large head, as had 6 of 17 siblings. Head circumference at birth was large in 7 of 10 babies and rate of head growth was excessive in 8 of 13. Skull x-ray showed suture diastasis in 7 infants. These families have a benign familial megalencephaly. It is important to recognise this so as to avoid unnecessary investigation and anxiety about normal children with large heads.

Brain↗
PubMed1978

Malformation of the cerebral cortex with heterotopia of the gray matter.

Developmental malformation of the cerebral cortex with heterotopia of the gray matter is a rare condition. It can present as unilateral megalencephaly, a localized mass, or focal cortical dysplasia. Four histologically confirmed cases are described in this report, and the findings from computed tomography as well as from other radiological diagnostic procedures are discussed.

Brain Neoplasms↗
PubMed2024

Expanding the phenotype and genotype spectrum of TAOK1 neurodevelopmental disorder and delineating TAOK2 neurodevelopmental disorder.

PURPOSE: The thousand and one kinase (TAOK) proteins are a group of serine/threonine-protein kinases involved in signaling pathways, cytoskeleton regulation, and neuronal development. TAOK1 variants are associated with a neurodevelopmental disorder (NDD) characterized by distinctive facial features, hypotonia, and feeding difficulties. TAOK2 variants have been reported to be associated with autism and early-onset obesity. However, a distinct TAOK2-NDD has not yet been delineated. METHODS: We retrospectively studied the clinical and genetic data of individuals recruited from several centers with TAOK1 and TAOK2 variants that were detected through exome and genome sequencing. RESULTS: We report 50 individuals with TAOK1 variants with associated phenotypes, including neurodevelopmental abnormalities (100%), macrocephaly (83%), and hypotonia (58%). We report male genital anomalies and hypoglycemia as novel phenotypes. Thirty-seven unique TAOK1 variants were identified. Most of the missense variants clustered in the protein kinase domain at residues that are intolerant to missense variation. We report 10 individuals with TAOK2 variants with associated phenotypes, including neurodevelopmental abnormalities (100%), macrocephaly (75%), autism (75%), and obesity (70%). CONCLUSION: We describe the largest cohort of TAOK1-NDD to date, to our knowledge, expanding its phenotype and genotype spectrum with 30 novel variants. We delineated the phenotype of a novel TAOK2-NDD associated with neurodevelopmental abnormalities, autism, macrocephaly, and obesity.

Humans↗