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Assessment of fetal brain abnormalities
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
Neuronal migration disorders are caused by the abnormal migration of neurons in the developing brain and nervous system. Neurons must migrate from the areas where they are born to the areas where they will settle into their proper neural circuits. Neuronal migration, which occurs as early as the second month of gestation, is controlled by a complex assortment of chemical guides and signals. When these signals are absent or incorrect, neurons do not end up where they belong. This can result in structurally abnormal or missing areas of the brain in the cerebral hemispheres, cerebellum, brainstem, or hippocampus, including schizencephaly, porencephaly, lissencephaly, agyria, macrogyria, pachygyria, microgyria, micropolygyria, neuronal heterotopias (including band heterotopia), agenesis of the corpus callosum, and agenesis of the cranial nerves. Symptoms vary according to the specific disorder and the degree of brain abnormality and subsequent neurologic losses, but often feature poor muscle tone and motor function, seizures, developmental delays, mental retardation, failure to grow and thrive, difficulties with feeding, swelling in the extremities, and a smaller than normal head. Most infants with a neuronal migration disorder appear normal, but some disorders have characteristic facial or skull features.
Assessment of fetal wellbeing
Published in Louise C Kenny, Jenny E Myers, Obstetrics, 2017
Detection rates of between 40 and 90% have been reported at the 20-week ‘anomaly’ scan. This means that a ‘normal scan’ is not a guarantee of a normal baby. A number of factors can influence the success of detecting an abnormality. Some are very difficult to visualize or to be absolutely certain about. Some conditions, for example hydrocephalus, may not have been obvious at the time of early scans. Neuronal migration disorders that affect cerebral development may not manifest until the third trimester. Women should be informed of the limitations of routine ultrasound screening and that detection rates vary by the type of fetal anomaly, the woman’s body mass index and the position of the unborn baby at the time of the scan. The position of the baby in the uterus will influence visualization of organs such as the heart, face and spine. Repeat scans are sometimes required if visualization is a problem in anticipation that the fetus will be in a more accessible position.
Combined exome analysis and exome depth assessment achieve a high diagnostic yield in an epilepsy case series, revealing significant genomic heterogeneity and novel mechanisms
Published in Expert Review of Molecular Diagnostics, 2023
Danai Veltra, Faidon-Nikolaos Tilemis, Nikolaos M. Marinakis, Maria Svingou, Anastasios Mitrakos, Konstantina Kosma, Irene Tsoutsou, Periklis Makrythanasis, Virginia Theodorou, Marina Katsalouli, Pelagia Vorgia, Georgios Niotakis, Georgios Vartzelis, Argirios Dinopoulos, Athanasios Evangeliou, Stella Mouskou, Anastasia Korona, Sotiria Mastroyianni, Antigone Papavasiliou, Maria Tzetis, Roser Pons, Joanne Traeger-Synodinos, Christalena Sofocleous
The application of NGS technologies, such as CES or WES, has raised the diagnostic yield in cases with epilepsy syndromes with substantial benefits to both the scientific and the patient communities. In this study, diligent clinical examination and multidisciplinary collaborations supported a phenotype driven interpretation of variants, resulting in a diagnostic yield of almost 60% (59.8%). The highest diagnostic yield was achieved for patients with genetic epilepsy with febrile seizures + (GEFS+, 5/5, 100%), followed by infantile spasms syndrome (ISS, 9/13, 69.2%), multiple seizure types (MST) and developmental and/or epileptic encephalopathy with spike-wave activation in sleep (D/EE-SWAS, 2/3, 66.6% for each syndrome) and DEE (34/52, 65.3%). No genetic diagnosis was reached in patients referred with sleep-related hypermotor epilepsy (SHE) and only one case with brain malformations of cortical development and epilepsy was resolved. Since low-level mosaicism in blood samples may escape WES diagnosis, possible underdiagnosis of cases associated with brain malformations or neuronal migration disorders could be hypothesized.
Neuropsychological and Social Characteristics of a 7 Year Old Child with Hypomelanosis of Ito Followed for 11 Years
Published in Developmental Neuropsychology, 2022
George P. Prigatano, Alexandra Novak, Vinodh Narayanan
The underlying brain mechanisms responsible for these developmental changes remain undetermined. Somatic mosaicism has been sufficiently thought to influence brain development that an NIMH-funded Brain Somatic Mosaicism Network (BSMN) has been established (Paquola, Erwin, & Gage, 2017). Disturbances in normal neuronal thinning or loss during brain development may contribute to cortical dysplasia reported in some patients with HI (Carmignac et al., 2021). Mosaic chromosomal anomalies may also contribute to specific cell abnormalities, especially those involving frontal cortex neurons (Paquola et al., 2017). These disturbances can further lead to neuronal migration disorders, which may contribute to neurodevelopmental disease (D’Gama & Walsh, 2018). It is interesting to note that, while rote verbal learning and memory appeared relatively unaffected in this patient with HI, the ability of this patient to recall multiple details and accurately relate and remember details and concepts of a story read to him did not appear to develop normally via teacher and parent’s descriptions of his academic difficulties. Frontal cortex mediated brain systems have been repeatedly implicated in this type of complex memory function (Moscovitch & Winocur, 2002).
De novo intracerebral arteriovenous malformations and a review of the theories of their formation
Published in British Journal of Neurosurgery, 2018
A. Dalton, G. Dobson, M. Prasad, N. Mukerji
MRI sensitivity ranges between 83–97% for AVM detection, with the greatest threat of a false negative resulting from compression of the shunt in ruptured AVMs. In the UK, DSA remains the gold standard for investigating AVMs, as with intracranial aneurysms. It is a possibility that in some of these reported cases there was some kind of pre-existing occult AVM that merely progressed. In 9 cases, however, DSA was shown to be negative on the initial workup and in six of these, there were no associated mass lesions that could be argued to be compressing a small pre-existing shunt. It is also interesting to note that, virtually, in all cases there was some prior insult to the brain including vascular problems (16 cases), trauma (2 cases) and radiation therapy (2 cases), inflammatory conditions (2 cases), epilepsy (5 cases) and two isolated cases of neuronal migration disorder and congenital hydrocephalus.