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Mejia M, Vargas Arango S, Vargas Vélez S, Pimiento Figueroa J. Prenatal Diagnosis of Hemimegalencephaly Using Radiological Methods: A Case Report. Cureus 2024; 16:e54456. [PMID: 38510871 PMCID: PMC10951679 DOI: 10.7759/cureus.54456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/19/2024] [Indexed: 03/22/2024] Open
Abstract
Hemimegalencephaly is a rare congenital anomaly characterized by an increase in the size and dysplastic involvement of one cerebral hemisphere, which can be partial or complete. It may also be associated with anomalies in the cerebellum and brainstem and, in some cases, be a part of different syndromes. The result of these abnormalities leads to intractable epilepsy and developmental delay. Diagnosis is typically made through imaging studies in the postnatal period, but it can also be done before birth. We present the case of a 23-week pregnant patient in whom a prenatal diagnosis of hemimegalencephaly was made, highlighting the need for fetal magnetic resonance imaging (MRI) to confirm the diagnosis.
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Affiliation(s)
- Marcia Mejia
- Radiology, Universidad de Antioquia, Medellin, COL
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Hart AR, Vasudevan C, Griffiths PD, Foulds N, Piercy H, de Lacy P, Boxall S, Howe D, Vollmer B. Antenatal counselling for prospective parents whose fetus has a neurological anomaly: part 2, risks of adverse outcome in common anomalies. Dev Med Child Neurol 2022; 64:23-39. [PMID: 34482539 DOI: 10.1111/dmcn.15043] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 07/31/2021] [Accepted: 08/02/2021] [Indexed: 12/14/2022]
Abstract
After diagnosis of a fetal neurological anomaly, prospective parents want to know the best and worst-case scenarios and an estimation of the risk to their infant of having an atypical developmental outcome. The literature on developmental outcomes for fetal neurological anomalies is poor: studies are characterized by retrospective design, small sample size, often no standardized assessment of development, and differing definitions of anomalies. This review provides an aide-memoir on the risks of adverse neurodevelopmental outcome for ventriculomegaly, cortical anomalies, microcephaly, macrocephaly, agenesis of the corpus callosum, posterior fossa anomalies, and myelomeningocele, to assist healthcare professionals in counselling. The data in this review should be used alongside recommendations on counselling and service design described in part 1 to provide antenatal counselling.
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Affiliation(s)
- Anthony R Hart
- Department of Perinatal and Paediatric Neurology, Sheffield Children's NHS Foundation Trust, Ryegate Children's Centre, Sheffield, UK
| | - Chakra Vasudevan
- Department of Neonatology, Bradford Royal Infirmary, Bradford, UK
| | - Paul D Griffiths
- Academic Unit of Radiology, Royal Hallamshire Hospital, University of Sheffield, Sheffield, UK
| | - Nicola Foulds
- Department of Clinical Genetics, Princess Anne Hospital, University Southampton NHS Foundation Trust, Southampton, UK
| | - Hilary Piercy
- The Centre for Health and Social Care, Sheffield Hallam University, Sheffield, UK
| | - Patricia de Lacy
- Department of Paediatric Neuosurgery, Sheffield Children's NHS Foundation Trust, Sheffield, UK
| | - Sally Boxall
- Wessex Fetal Medicine Unit, Princess Anne Hospital, Southampton, UK
| | - David Howe
- Wessex Fetal Medicine Unit, Princess Anne Hospital, Southampton, UK
| | - Brigitte Vollmer
- Clinical and Experimental Sciences, Faculty of Medicine, Paediatric and Neonatal Neurology, Southampton Children's Hospital, University Hospital Southampton NHS Foundation Trust, University of Southampton, Southampton, UK
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Mühlebner A, Bongaarts A, Sarnat HB, Scholl T, Aronica E. New insights into a spectrum of developmental malformations related to mTOR dysregulations: challenges and perspectives. J Anat 2019; 235:521-542. [PMID: 30901081 DOI: 10.1111/joa.12956] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/15/2019] [Indexed: 12/20/2022] Open
Abstract
In recent years the role of the mammalian target of rapamycin (mTOR) pathway has emerged as crucial for normal cortical development. Therefore, it is not surprising that aberrant activation of mTOR is associated with developmental malformations and epileptogenesis. A broad spectrum of malformations of cortical development, such as focal cortical dysplasia (FCD) and tuberous sclerosis complex (TSC), have been linked to either germline or somatic mutations in mTOR pathway-related genes, commonly summarised under the umbrella term 'mTORopathies'. However, there are still a number of unanswered questions regarding the involvement of mTOR in the pathophysiology of these abnormalities. Therefore, a monogenetic disease, such as TSC, can be more easily applied as a model to study the mechanisms of epileptogenesis and identify potential new targets of therapy. Developmental neuropathology and genetics demonstrate that FCD IIb and hemimegalencephaly are the same diseases. Constitutive activation of mTOR signalling represents a shared pathogenic mechanism in a group of developmental malformations that have histopathological and clinical features in common, such as epilepsy, autism and other comorbidities. We seek to understand the effect of mTOR dysregulation in a developing cortex with the propensity to generate seizures as well as the aftermath of the surrounding environment, including the white matter.
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Affiliation(s)
- A Mühlebner
- Department of Neuropathology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - A Bongaarts
- Department of Neuropathology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - H B Sarnat
- Departments of Paediatrics, Pathology (Neuropathology) and Clinical Neurosciences, University of Calgary Cumming School of Medicine and Alberta Children's Hospital Research Institute (Owerko Centre), Calgary, AB, Canada
| | - T Scholl
- Department of Paediatric and Adolescent Medicine, Medical University of Vienna, Vienna, Austria
| | - E Aronica
- Department of Neuropathology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,Stichting Epilepsie Instellingen Nederland (SEIN), Amsterdam, The Netherlands
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Andescavage NN, du Plessis A, McCarter R, Serag A, Evangelou I, Vezina G, Robertson R, Limperopoulos C. Complex Trajectories of Brain Development in the Healthy Human Fetus. Cereb Cortex 2018; 27:5274-5283. [PMID: 27799276 DOI: 10.1093/cercor/bhw306] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 09/10/2016] [Indexed: 11/13/2022] Open
Abstract
This study characterizes global and hemispheric brain growth in healthy human fetuses during the second half of pregnancy using three-dimensional MRI techniques. We studied 166 healthy fetuses that underwent MRI between 18 and 39 completed weeks gestation. We created three-dimensional high-resolution reconstructions of the brain and calculated volumes for left and right cortical gray matter (CGM), fetal white matter (FWM), deep subcortical structures (DSS), and the cerebellum. We calculated the rate of growth for each tissue class according to gestational age and described patterns of hemispheric growth. Each brain region demonstrated major increases in volume during the second half of gestation, the most pronounced being the cerebellum (34-fold), followed by FWM (22-fold), CGM (21-fold), and DSS (10-fold). The left cerebellar hemisphere, CGM, and DSS had larger volumes early in gestation, but these equalized by term. It has been increasingly recognized that brain asymmetry evolves throughout the human life span. Advanced quantitative MRI provides noninvasive measurements of early structural asymmetry between the left and right fetal brain that may inform functional and behavioral laterality differences seen in children and young adulthood.
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Affiliation(s)
- Nickie N Andescavage
- Division of Neonatology, Children's National Health System, Washington, DC 20010, USA.,Department of Pediatrics, George Washington University School of Medicine, Washington, DC 20052, USA
| | - Adre du Plessis
- Department of Pediatrics, George Washington University School of Medicine, Washington, DC 20052, USA.,Division of Fetal and Translational Medicine, Children's National Health System, Washington, DC 20010, USA
| | - Robert McCarter
- Division of Biostatistics and Informatics, Children's National Health System, Washington, DC 20010, USA
| | - Ahmed Serag
- Division of Diagnostic Imaging and Radiology, Children's National Health System, Washington, DC 20010, USA
| | - Iordanis Evangelou
- Division of Diagnostic Imaging and Radiology, Children's National Health System, Washington, DC 20010, USA
| | - Gilbert Vezina
- Division of Diagnostic Imaging and Radiology, Children's National Health System, Washington, DC 20010, USA.,Department of Radiology, George Washington University School of Medicine, Washington, DC 20052, USA
| | - Richard Robertson
- Department of Radiology, Children's Hospital Boston, Boston, MA 02115, USA.,Department of Radiology, Harvard Medical School, Cambridge, MA 02115, USA
| | - Catherine Limperopoulos
- Division of Fetal and Translational Medicine, Children's National Health System, Washington, DC 20010, USA.,Division of Diagnostic Imaging and Radiology, Children's National Health System, Washington, DC 20010, USA.,Department of Radiology, George Washington University School of Medicine, Washington, DC 20052, USA
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Somatic mosaicism: implications for disease and transmission genetics. Trends Genet 2015; 31:382-92. [PMID: 25910407 DOI: 10.1016/j.tig.2015.03.013] [Citation(s) in RCA: 190] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 03/17/2015] [Accepted: 03/18/2015] [Indexed: 11/21/2022]
Abstract
Nearly all of the genetic material among cells within an organism is identical. However, single-nucleotide variants (SNVs), small insertions/deletions (indels), copy-number variants (CNVs), and other structural variants (SVs) continually accumulate as cells divide during development. This process results in an organism composed of countless cells, each with its own unique personal genome. Thus, every human is undoubtedly mosaic. Mosaic mutations can go unnoticed, underlie genetic disease or normal human variation, and may be transmitted to the next generation as constitutional variants. We review the influence of the developmental timing of mutations, the mechanisms by which they arise, methods for detecting mosaic variants, and the risk of passing these mutations on to the next generation.
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