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hemimegalencephaly

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https://www.readbyqxmd.com/read/29778488/the-2016-bernard-sachs-lecture-timing-in-morphogenesis-and-genetic-gradients-during-normal-development-and-in-malformations-of-the-nervous-system
#1
REVIEW
Harvey B Sarnat
Nervous system development is quadradimensional. Both normal ontogenesis and developmental malformations are explained in the context of the fourth dimension, timing. Timing of the onset of either the genetic expression of a mutation or an epigenetic event that may be teratogenic is primordial in determining morphogenesis and the forms of malformations with their functional consequences. Multiple genotypes may cause similar phenotypes or a single genotype with different degrees of retained normal genetic expression may result in variable phenotypes...
March 30, 2018: Pediatric Neurology
https://www.readbyqxmd.com/read/29594439/dysplastic-megalencephaly-phenotype-presenting-with-prenatal-high-output-cardiac-failure
#2
Fernanda Del Campos Braojos, Carolina V A Guimaraes
Dysplastic megalencephaly, also known as bilateral hemimegalencephaly, is a rare cerebral malformation characterized by bilateral cerebral hemisphere overgrowth and extensive malformation of cortical development. Affected patients present clinically with intractable seizures, severe neurological impairment and global developmental delay. There is a small body of literature reporting megalencephaly's association with neonatal high-output cardiac failure and a lack of literature describing prenatal findings. We report a case of dysplastic megalencephaly presenting with progressive high-output cardiac failure during fetal life...
March 28, 2018: Pediatric Radiology
https://www.readbyqxmd.com/read/29444762/hemimegalencephaly-with-bannayan-riley-ruvalcaba-syndrome
#3
Ryan Ghusayni, Monisha Sachdev, William Gallentine, Mohamad A Mikati, Marie T McDonald
Hemimegalencephaly is known to occur in Proteus syndrome, but has not been reported, to our knowledge, in the other PTEN mutation-related syndrome of Bannayan-Riley-Ruvalcaba. Here, we report a patient with Bannayan-Riley-Ruvalcaba syndrome who also had hemimegalencephaly and in whom the hemimegalencephaly was evident well before presentation of the characteristic manifestations of Bannayan-Riley-Ruvalcaba syndrome. An 11-year-old boy developed drug-resistant focal seizures on the fifth day of life. MRI revealed left hemimegalencephaly...
February 1, 2018: Epileptic Disorders: International Epilepsy Journal with Videotape
https://www.readbyqxmd.com/read/29359340/review-mechanistic-target-of-rapamycin-mtor-pathway-focal-cortical-dysplasia-and-epilepsy
#4
REVIEW
E Marsan, S Baulac
Over the last decade, there has been increasing evidence that hyperactivation of the mechanistic target of rapamycin (mTOR) pathway is a hallmark of malformations of cortical development such as focal cortical dysplasia (FCD) or hemimegalencephaly. The mTOR pathway governs protein and lipid synthesis, cell growth and proliferation as well as metabolism and autophagy. The molecular genetic aetiology of mTOR hyperactivation has only been recently clarified. This article will review the current and still evolving genetic advances in the elucidation of the molecular basis of FCD...
February 2018: Neuropathology and Applied Neurobiology
https://www.readbyqxmd.com/read/29281825/somatic-mutations-activating-the-mtor-pathway-in-dorsal-telencephalic-progenitors-cause-a-continuum-of-cortical-dysplasias
#5
Alissa M D'Gama, Mollie B Woodworth, Amer A Hossain, Sara Bizzotto, Nicole E Hatem, Christopher M LaCoursiere, Imad Najm, Zhong Ying, Edward Yang, A James Barkovich, David J Kwiatkowski, Harry V Vinters, Joseph R Madsen, Gary W Mathern, Ingmar Blümcke, Annapurna Poduri, Christopher A Walsh
Focal cortical dysplasia (FCD) and hemimegalencephaly (HME) are epileptogenic neurodevelopmental malformations caused by mutations in mTOR pathway genes. Deep sequencing of these genes in FCD/HME brain tissue identified an etiology in 27 of 66 cases (41%). Radiographically indistinguishable lesions are caused by somatic activating mutations in AKT3, MTOR, and PIK3CA and germline loss-of-function mutations in DEPDC5, NPRL2, and TSC1/2, including TSC2 mutations in isolated HME demonstrating a "two-hit" model...
December 26, 2017: Cell Reports
https://www.readbyqxmd.com/read/29279945/dysplasia-and-overgrowth-magnetic-resonance-imaging-of-pediatric-brain-abnormalities-secondary-to-alterations-in-the-mechanistic-target-of-rapamycin-pathway
#6
REVIEW
Shai Shrot, Misun Hwang, Carl E Stafstrom, Thierry A G M Huisman, Bruno P Soares
The current classification of malformations of cortical development is based on the type of disrupted embryological process (cell proliferation, migration, or cortical organization/post-migrational development) and the resulting morphological anomalous pattern of findings. An ideal classification would include knowledge of biological pathways. It has recently been demonstrated that alterations affecting the mechanistic target of rapamycin (mTOR) signaling pathway result in diverse abnormalities such as dysplastic megalencephaly, hemimegalencephaly, ganglioglioma, dysplastic cerebellar gangliocytoma, focal cortical dysplasia type IIb, and brain lesions associated with tuberous sclerosis...
February 2018: Neuroradiology
https://www.readbyqxmd.com/read/29246093/targeting-the-mammalian-target-of-rapamycin-for-epileptic-encephalopathies-and-malformations-of-cortical-development
#7
Anna Jeong, Michael Wong
Malformations of cortical development represent a common cause of epileptic encephalopathies and drug-resistant epilepsy in children. As current treatments are often ineffective, new therapeutic targets are needed for epileptic encephalopathies associated with cortical malformations. The mechanistic/mammalian target of rapamycin (mTOR) pathway constitutes a signaling pathway that drives cellular and molecular mechanisms of epileptogenesis in a variety of focal cortical malformations. mTOR inhibitors prevent epilepsy and associated pathogenic mechanisms of epileptogenesis in mouse models of tuberous sclerosis complex and are currently in clinical trials for drug-resistant seizures in these patients...
January 2018: Journal of Child Neurology
https://www.readbyqxmd.com/read/28969385/mutations-of-akt3-are-associated-with-a-wide-spectrum-of-developmental-disorders-including-extreme-megalencephaly
#8
Diana Alcantara, Andrew E Timms, Karen Gripp, Laura Baker, Kaylee Park, Sarah Collins, Chi Cheng, Fiona Stewart, Sarju G Mehta, Anand Saggar, László Sztriha, Melinda Zombor, Oana Caluseriu, Ronit Mesterman, Margot I Van Allen, Adeline Jacquinet, Sofia Ygberg, Jonathan A Bernstein, Aaron M Wenger, Harendra Guturu, Gill Bejerano, Natalia Gomez-Ospina, Anna Lehman, Enrico Alfei, Chiara Pantaleoni, Valerio Conti, Renzo Guerrini, Ute Moog, John M Graham, Robert Hevner, William B Dobyns, Mark O'Driscoll, Ghayda M Mirzaa
Mutations of genes within the phosphatidylinositol-3-kinase (PI3K)-AKT-MTOR pathway are well known causes of brain overgrowth (megalencephaly) as well as segmental cortical dysplasia (such as hemimegalencephaly, focal cortical dysplasia and polymicrogyria). Mutations of the AKT3 gene have been reported in a few individuals with brain malformations, to date. Therefore, our understanding regarding the clinical and molecular spectrum associated with mutations of this critical gene is limited, with no clear genotype-phenotype correlations...
October 1, 2017: Brain: a Journal of Neurology
https://www.readbyqxmd.com/read/28924292/hemimegalencephaly-with-intractable-epilepsy-a-case-report
#9
Prem Chand, Muhammad Faraz Raghib, Muhammad Sohail Salat, Fazal Manzoor Arain
Isolated Hemimegalencephaly (iHME) is a rare form of congenital malformation of cortical development.It is characterized by enlargement of all or part of one cerebral hemisphere. It typically presents with intractable seizures, mental retardation, developmental delay, contralateral hemiparesis and hemianopia. The patient was a five and half month's old baby girl who presented first with focal seizures at 10th day of life. No other physical or behavioral abnormality was noted. However, Initial EEG showed excessive sharp EEG transients more over the right hemisphere, repeated EEG showed spikes, polyspikes, sharps and slow wave discharges predominately over right hemisphere...
September 2017: JPMA. the Journal of the Pakistan Medical Association
https://www.readbyqxmd.com/read/28904588/a-case-of-epilepsia-partialis-continua-due-to-linear-nevus-syndrome-with-hemimegalencephaly
#10
Leema Pauline Cornelius, Vivekasaravanan Raju, Ravi A Lalapet
Epilepsia partialis continua (EPC) is a form of focal status epilepticus often refractory to anticonvulsant therapy. A wide range of abnormalities such as inflammatory, vascular, metabolic-toxic, developmental malformations, and neoplasia cause EPC. Linear nevus syndrome with hemimegalencephaly is one of the developmental malformations that can present with EPC.
April 2017: Journal of Pediatric Neurosciences
https://www.readbyqxmd.com/read/28864461/somatic-uniparental-disomy-of-chromosome-16p-in-hemimegalencephaly
#11
Nicole G Griffin, Kenneth D Cronin, Nicole M Walley, Christine M Hulette, Gerald A Grant, Mohamad A Mikati, Heather G LaBreche, Catherine W Rehder, Andrew S Allen, Peter B Crino, Erin L Heinzen
Hemimegalencephaly (HME) is a heterogeneous cortical malformation characterized by enlargement of one cerebral hemisphere. Somatic variants in mammalian target of rapamycin (mTOR) regulatory genes have been implicated in some HME cases; however, ∼70% have no identified genetic etiology. Here, we screened two HME patients to identify disease-causing somatic variants. DNA from leukocytes, buccal swabs, and surgically resected brain tissue from two HME patients were screened for somatic variants using genome-wide genotyping arrays or sequencing of the protein-coding regions of the genome...
September 2017: Cold Spring Harbor Molecular Case Studies
https://www.readbyqxmd.com/read/28799142/what-to-do-in-failed-hemispherotomy-our-clinical-series-and-review-of-the-literature
#12
REVIEW
Andrea Bartoli, Y El Hassani, B Jenny, S Momjian, C M Korff, M Seeck, S Vulliemoz, K Schaller
Hemispherotomy is an established surgical technique to cure or palliate selected, mostly young patients suffering from refractory epilepsy. However, a few patients continue to have seizures despite the surgical hemispherical disconnection. We present a case series of patients who underwent redo hemispherotomy after a first unsuccessful hemispherical disconnection and provide a roadmap for subsequent workup and treatment. The institutional database of epilepsy surgery was reviewed. Twenty-four patients who underwent hemispherotomies for refractory epilepsy were identified between 2007 and 2016...
January 2018: Neurosurgical Review
https://www.readbyqxmd.com/read/28553400/proteus-syndrome-with-neurological-manifestations-a-rare-presentation
#13
Pallavi Sachdeva, Priyanka Minocha, Rohit Jain, Sadasivan Sitaraman, Manisha Goyal
Proteus syndrome (PS) is an extremely rare and complex disorder. Approximately 200 cases have been reported, and it seems to affect people of all ethnic and racial groups. PS is characterized by segmental overgrowth of multiple tissues and organs including vascular malformations, lipomatous overgrowth, hyperpigmentation, and various types of nevi. We hereby present a 7-year-old boy who presented with seizures and overgrowth of one-half of the body. Although classical physical features have been described, epilepsy and other neurological manifestations are rarely reported features of PS...
January 2017: Journal of Pediatric Neurosciences
https://www.readbyqxmd.com/read/28427592/pathologic-active-mtor-mutation-in-brain-malformation-with-intractable-epilepsy-leads-to-cell-autonomous-migration-delay
#14
Sae Hanai, Sayuri Sukigara, Hongmei Dai, Tomoo Owa, Shin-Ichi Horike, Taisuke Otsuki, Takashi Saito, Eiji Nakagawa, Naoki Ikegaya, Takanobu Kaido, Noriko Sato, Akio Takahashi, Kenji Sugai, Yuko Saito, Masayuki Sasaki, Mikio Hoshino, Yu-Ichi Goto, Schuichi Koizumi, Masayuki Itoh
The activation of phosphatidylinositol 3-kinase-AKTs-mammalian target of rapamycin cell signaling pathway leads to cell overgrowth and abnormal migration and results in various types of cortical malformations, such as hemimegalencephaly (HME), focal cortical dysplasia, and tuberous sclerosis complex. However, the pathomechanism underlying abnormal cell migration remains unknown. With the use of fetal mouse brain, we performed causative gene analysis of the resected brain tissues from a patient with HME and investigated the pathogenesis...
May 2017: American Journal of Pathology
https://www.readbyqxmd.com/read/28424599/electrophysiological-sequelae-of-hemispherotomy-in-ipsilateral-human-cortex
#15
Ammar H Hawasli, Ravi Chacko, Nicholas P Szrama, David T Bundy, Mrinal Pahwa, Chester K Yarbrough, Brian J Dlouhy, David D Limbrick, Dennis L Barbour, Matthew D Smyth, Eric C Leuthardt
Objectives: Hemispheric disconnection has been used as a treatment of medically refractory epilepsy and evolved from anatomic hemispherectomy to functional hemispherectomies to hemispherotomies. The hemispherotomy procedure involves disconnection of an entire hemisphere with limited tissue resection and is reserved for medically-refractory epilepsy due to diffuse hemispheric disease. Although it is thought to be effective by preventing seizures from spreading to the contralateral hemisphere, the electrophysiological effects of a hemispherotomy on the ipsilateral hemisphere remain poorly defined...
2017: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/28377884/evolution-of-epilepsy-in-hemimegalencephaly-from-infancy-to-adulthood-case-report-and-review-of-the-literature
#16
Kristin M Ikeda, Seyed M Mirsattari
Hemimegalencephaly (HME) is a rare disorder of cortical development with overgrowth of one cerebral hemisphere. Patients have intellectual delay, hemiparesis and severe epilepsy. Drug-resistant epilepsy is often treated with a hemispherectomy. We review the literature on HME natural history and report a 26-year-old man with HME who did not undergo hemispherectomy in childhood with recurrent focal convulsive or non-convulsive status epilepticus. Few patients with HME have been followed into adulthood. Reported adult cases have milder epilepsy or underwent hemispherectomy in childhood...
2017: Epilepsy & Behavior Case Reports
https://www.readbyqxmd.com/read/28348960/delayed-diagnosis-of-shunt-overdrainage-following-functional-hemispherotomy-and-ventriculoperitoneal-shunt-placement-in-a-hemimegalencephaly-patient
#17
Yasunori Nagahama, David Peters, Sho Kumonda, Adam Vesole, Charuta Joshi, Brian J Dlouhy, Hiroto Kawasaki
Shunt overdrainage represents a nebulous condition of variable clinical and imaging presentations, where the diagnosis is primarily clinical. The condition presents a diagnostic challenge particularly in patients with cognitive impairment and developmental delays. Here we present a 3-year-old boy with drug-resistant focal onset seizures due to hemimegalencephaly who previously underwent functional hemispherotomy followed by ventriculoperitoneal shunt placement for postoperative hydrocephalus. The subsequent clinical course was complicated by delayed diagnosis of shunt overdrainage in the absence of significant image findings...
2017: Epilepsy & Behavior Case Reports
https://www.readbyqxmd.com/read/28195914/ictal-pet-in-ohtahara-syndrome-with-hemimegalencephaly
#18
Shambo Guha Roy, Madhavi Tripathi, Manjari Tripathi, Bhargavi Ramanujam, Abhinav Singhal, Chandrasekhar Bal
Ohtahara syndrome is one of the causes of infantile epilepsies, which presents with refractory seizures and characteristic EEG changes. It is often associated with structural anomalies in the brain. We report a case of 5-month-old girl with Ohtahara syndrome with hemimegalencephaly who presented with refractory seizures and ictal FDG PET/CT helped in localizing the seizure focus.
May 2017: Clinical Nuclear Medicine
https://www.readbyqxmd.com/read/27796549/-endovascular-embolic-hemispherectomy-a-strategy-for-the-initial-management-of-catastrophic-holohemispheric-epilepsy-in-the-neonate
#19
Chima Oluigbo, Monica S Pearl, Tammy N Tsuchida, Taeun Chang, Cheng-Ying Ho, William D Gaillard
PURPOSE: Conflicting challenges abound in the management of the newborn with intractable epilepsy related to hemimegalencephaly. Early hemispherectomy to stop seizures and prevent deleterious consequences to future neurocognitive development must be weighed against the technical and anesthetic challenges of performing major hemispheric surgery in the neonate. METHODS: We hereby present our experience with two neonates with hemimegalencephaly and intractable seizures who were managed using a strategy of initial minimally invasive embolization of the cerebral blood supply to the involved hemisphere...
March 2017: Child's Nervous System: ChNS: Official Journal of the International Society for Pediatric Neurosurgery
https://www.readbyqxmd.com/read/27781032/genetic-basis-of-brain-malformations
#20
REVIEW
Elena Parrini, Valerio Conti, William B Dobyns, Renzo Guerrini
Malformations of cortical development (MCD) represent a major cause of developmental disabilities, severe epilepsy, and reproductive disadvantage. Genes that have been associated to MCD are mainly involved in cell proliferation and specification, neuronal migration, and late cortical organization. Lissencephaly-pachygyria-severe band heterotopia are diffuse neuronal migration disorders causing severe global neurological impairment. Abnormalities of the LIS1, DCX, ARX, RELN, VLDLR, ACTB, ACTG1, TUBG1, KIF5C, KIF2A, and CDK5 genes have been associated with these malformations...
September 2016: Molecular Syndromology
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