DOCSLIB.ORG

Hemimegalencephaly: a Longitudinal MR Study

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Hemimegalencephaly: a Longitudinal MR Study Hemimegalencephaly: A Longitudinal MR Study Samuel M. Wolpert, Alan Cohen, and Mark H. Libenson Summary: An infant with hemimegalencephaly was studied with Seizures persisted, occurring many times daily. Two clin­ MR at 5 days and again at 10 months of age. The initial scan ical seizure types were recognized: one consisted of forced showed an abnormally large left cerebral hemisphere. At the age eye deviation to the right associated with clonic move­ of 10 months, the left cerebral hemisphere was smaller than the ments of the right side, and the other consisted of blinking, right-an apparent left-sided micrencephaly caused by normal facial twisting, and clonic movement of all limbs. growth of the right hemisphere and arrested growth of the left. Initial neurologic examination showed mild doli ­ The age of imaging of a patient with hemimegalencephaly can be chocephaly with a head circumference in the 50th to 75th important if the correct diagnosis is to be made. percentile and mild axial hypotonia. MR images obtained when the patient was 5 days old demonstrated an abnor­ Index terms: Megalencephaly; Brain, abnormalities and anoma­ mally large left cerebral hemisphere with pachygyria, lies; Brain, magnetic resonance; Pediatric neuroradiology thickened cortex, and periventricular cortical heterotopias (Fig 1 ). A diagnosis of left unilateral megalencephaly was Hemimegalencephaly, or unilateral megalen­ made. cephaly, is a rare anomaly of neuronal migra­ Electroencephalography demonstrated virtually contin­ tion and proliferation that usually presents with uous electrographic seizure activity referable to the left macrocephaly, intractable seizures, and devel­ hemisphere. Seizures remained refractory to multiagent opment of later contralateral hemiparesis and pharmacotherapy that included phenobarbital, phenytoin, mental retardation. Although usually unassoci­ valproic acid, and carbamazepine. The patient remained ated with other conditions, it has been described severely developmentally delayed. Head control was poor, in association with the linear sebaceous nevus and a left gaze preference and right homonymous hemi­ syndrome (1), the Klippel-Trenaunay-Weber anopsia were evident. A dense right hemiparesis devel­ syndrome (2), neurofibromatosis (3), and the oped with fisting of the right hand. MR images were re­ epidermal nevus syndrome (4). Somatic hemi­ peated when the patient was 10 months old (Fig 2). These hypertrophy generally is absent in the isolated demonstrated apparent asymmetric growth of the brain: form of the disease (5-13) but may occur in the previously described enlarged left cerebral hemisphere some patients (14, 15). There are autopsy (6), was now smaller than the right cerebral hemisphere, with evidence of central and peripheral atrophy of the left ce­ computed tomography (CT) (8), and magnetic rebral hemisphere. resonance (MR) (5) reports of the anomaly. In A left hemispherectomy was performed when the pa­ this paper, we report on an infant studied with tient was 1 0 months old. Intraoperative electrocorticogra­ MR at the age of 5 days and again at 10 months. phy demonstrated continuous multifocal seizure activity During this period, striking changes in the ap­ occurring over the left hemisphere convexity. The left pearance of the brain occurred. hemisphere appeared bosselated, and pathologic exami­ nation revealed polymicrogyria with gray matter heteroto­ pias. A calcarine cortex could not be identified. The sylvian Case Report fissure was abnormall y wide and the ventricle extreme ly The patient was the product of an uncomplicated preg­ large. nancy and presented with prolonged seizure activity on the The patient's seizures resolved after hemispherectomy, first day of life. He was born via spontaneous vaginal and he demonstrated dramatic neurologic improvement. delivery at 7 pounds 4 ounces to a healthy 26-year-old Two months after surgery a ventricular shunt was inserted mother. There was no family history of neurologic disease. to control hydrocephalus. At follow-up examination at 23 Seizures first developed when the patient was 2 hours old. months of age, he had remained seizure-free since the Received September 21 , 1992; accepted after rev ision February 22, 1993. From the Section of Neuroradiology (S.M.W.), Depa rtment of Neurosurgery (A.C.) , and Division of Pediatric Neurology (M.H.L.) , New England Med ical Center Hospitals, Boston. Address reprint requests to Samuel M. Wolpert, MD, 750 Washington St. Boston, MA 02111. AJNR 15:1 479-1482, Sep 1994 0195-6108/94/1508-1 479 © American Society of Neu roradiology 1479 1480 WOLPERT AJNR: 15, September 1994 Fig 1. A and B, 5 days of age. A xial T l -weighted MR image, 650/20/ 1 (repeti­ tion time/echo time/excitations) through central white m atter dem onstrates enlarged abnormal left hemisphere with thic k gray m atter and pachygyria ( w hite arrows) and hyperintense white matter (blac/c arrows). B is 8 mm, higher than A . Note also en­ larg ed left lateral ventricle. (Right lateral ventricle, not shown here, was seen on lower sections.) C and 0 , A xial T2-weighted images, 3000/1 40/1 , at sa m e levels as A and B dem onstrates thick pachygyri c gray m atter (open arrows), enlarg ed left lateral ventri­ cle, and minimal hyperintensity of sur­ rounding white m atter (arrows) caused pre­ sumably by gliosis. D immediate postoperative peri od, was able to sit if placed, swelling is usually present (17). In unilateral used three words specifi call y, and demonstrated a mild megalencephaly (hemimegalencephaly), the right hemiparesis and a left gaze preference. The electro­ white matter is usually excessive, and the nerve encephalogra m showed a normal posterior rh ythm on the right a nd voltage depression on the left ; there was no cells are larger and less densely packed than on residual epile ptiform activity. the normal half of the brain ( 6), and polymicro­ gyria, neuronal heterotopias (11), and lissen­ cephaly occur. Unilateral megalencephaly is Discussion probably related to an interference in normal Unilateral megalencephaly is considerably neuronal migration along radially oriented glial less common than the generalized fo rm , which fibers (18, 19). Gliosis and/or heterotopic gray has been divided into anatomic megalen­ matter may occur in the white matter (5). cephaly (including the neurocutaneous syn­ Brain growth after birth is largely determined dromes and a variety of genetic syndromes) by glial rather than by neuronal growth (20). In and metabolic megalencephaly (1 6). In this lat­ an infant with hemimegalencephaly, it is ex­ ter group of disorders, which includes Tay­ pected that through childhood the normal hemi­ Sachs disease and other gangliosidoses , Cana­ sphere should undergo normal growth, matura­ van disease, Alexander disease, and some of tion, and myelination. The MR appearances in the mucopolysaccharidoses, white matter this case report are consistent with normal neu- AJNR: 15, September 1994 HEMIMEGALENCEPHALY 1481 Fig 2. A and B, 10 m onths of age. Axial T1-weighted MR image 650/20/1 at ap­ proximately the same levels as Figure 1 A and B dem onstrate a sm aller left than right hemisphere. Again left-sided pachygyria is seen (arrows) . The subarachnoid spaces surrounding the hemisphere are wider on the left than on the right side. Note that the left hemicranium remains larger than the right des pite the atrophic underl ying hemisphere. C and 0 , Axial T2-weighted images, 3000/ 140/1 at the same levels as A and B demonstrate again a smaller left than right hemisphere. Again left-sided pachygyria is noted. There are hyperintense areas (arrows) surrounding the left occipital horn because of gliosis. D ronal and glial proliferation in the "normal" with hemimegalencephaly. The child did not hemisphere. It is not clear what later effect the in experience any clinical event during his course utero event that lead to the subsequent malde­ that would account for the failure of the affected velopment and abnormal prenatal enlargement hemisphere to grow. One could speculate that of the left hemisphere (likely occurring in the the patient's poorly controlled seizures were re­ second trimester of pregnancy) should have on sponsible for some portion of the growth arrest later brain growth. It would not be unexpected of the involved hemisphere, but the extent of the that such a severely disorganized region of ce­ growth differential makes seizures as the sole rebrum would have limited future growth poten­ explanation for the discrepancy implausible. tial. A review of the literature, either through longitudinal studies or in studies of patients di­ References agnosed in the first years of life, however, fails to demonstrate this consequence of differential 1. Hag er BC , Dyme lZ, Guertin SR, Tyler RJ, Tryciecky EW, Fratkin brain growth in patients with hemimegalen­ JD. Linear nevus seba ceous sy ndrome: megalenceph aly and het­ erotopic gray matter. Ped iatr f'leuro/1991 ;7:45-49 cephaly. We cannot account for the lack of sim­ 2. Burke JP, West NF, Strachan IM. Congenital nysta gmus, ani ­ ilar descriptions in the literature of differential somyopia , and hemimega lence phaly in the Klippei-Trenaunay­ growth of the cerebral hemispheres in patients Weber syndrome. J Pediatr Ophthal Strabis 1991 ;28:41 - 44 1482 WOLPERT AJNR: 15, September 1994 3. Cusmai R, Curatolo P, Mangano S, Cheminal R, Echenne B. Hemi­ 12. Tijiam AT, Stefanko S, Schenk VWD, de Vlieger M. Infantile megalencephaly and neurofibromatosis. Neuropediatrics 1990; spasm associated with hemihypsarrhythmia and hemimegalen­ 21 :179-182 cephaly. Deu fvled Child Neurol1978;20:779-798 4. Pavone L, Curatolo P, Rizzo R, et al. Epidermal nevus syndrom e: 13. Townsend JJ, Nielsen SL, Malamud N. Unilateral m ega len­ a neurologic variant with hemimegalencephaly, gyral malforma­ cephaly: hamartoma or neoplasm? Neurology 1975;25:448-453 tion, mental retardation, seizures, and facial hemihypertrophy. 14. Hallervorden J . Microscopic findings in brain in case of congenital Neurology 1991 ;41(Part 1):266-271 hemihypertrophy of left side of body including brain.
Load more

Recommended publications
  • Paternal Factors and Schizophrenia Risk: De Novo Mutations and Imprinting
    Paternal Factors and Schizophrenia Risk: De Novo Mutations and Imprinting by Dolores Malaspina Downloaded from https://academic.oup.com/schizophreniabulletin/article/27/3/379/1835092 by guest on 23 September 2021 Abstract (Impagnatiello et al. 1998; Kao et al. 1998), but there is no consensus that any particular gene plays a meaning- There is a strong genetic component for schizophrenia ful role in the etiology of schizophrenia (Hyman 2000). risk, but it is unclear how the illness is maintained in Some of the obstacles in genetic research in schiz- the population given the significantly reduced fertility ophrenia are those of any complex disorder, and include of those with the disorder. One possibility is that new incomplete penetrance, polygenic interaction (epista- mutations occur in schizophrenia vulnerability genes. sis), diagnostic instability, and variable expressivity. If so, then those with schizophrenia may have older Schizophrenia also does not show a clear Mendelian fathers, because advancing paternal age is the major inheritance pattern, although segregation analyses have source of new mutations in humans. This review variably supported dominant, recessive, additive, sex- describes several neurodevelopmental disorders that linked, and oligogenic inheritance (Book 1953; Slater have been associated with de novo mutations in the 1958; Garrone 1962; Elston and Campbell 1970; Slater paternal germ line and reviews data linking increased and Cowie 1971; Karlsson 1972; Stewart et al. 1980; schizophrenia risk with older fathers. Several genetic Risch 1990a, 1990fc; reviewed by Kendler and Diehl mechanisms that could explain this association are 1993). Furthermore, both nonallelic (Kaufmann et al. proposed, including paternal germ line mutations, 1998) and etiologic heterogeneity (Malaspina et al.
    [Show full text]
  • Bhagwan Moorjani, MD, FAAP, FAAN • Requires Knowledge of Normal CNS Developmental (I.E
    1/16/2012 Neuroimaging in Childhood • Neuroimaging issues are distinct from Pediatric Neuroimaging in adults Neurometabolic-degenerative disorder • Sedation/anesthesia and Epilepsy • Motion artifacts Bhagwan Moorjani, MD, FAAP, FAAN • Requires knowledge of normal CNS developmental (i.e. myelin maturation) • Contrast media • Parental anxiety Diagnostic Approach Neuroimaging in Epilepsy • Age of onset • Peak incidence in childhood • Static vs Progressive • Occurs as a co-morbid condition in many – Look for treatable causes pediatric disorders (birth injury, – Do not overlook abuse, Manchausen if all is negative dysmorphism, chromosomal anomalies, • Phenotype presence (syndromic, HC, NCS, developmental delays/regression) systemic involvement) • Predominant symptom (epilepsy, DD, • Many neurologic disorders in children weakness/motor, psychomotor regression, have the same chief complaint cognitive/dementia) 1 1/16/2012 Congenital Malformation • Characterized by their anatomic features • Broad categories: based on embryogenesis – Stage 1: Dorsal Induction: Formation and closure of the neural tube. (Weeks 3-4) – Stage 2: Ventral Induction: Formation of the brain segments and face. (Weeks 5-10) – Stage 3: Migration and Histogenesis: (Months 2-5) – Stage 4: Myelination: (5-15 months; matures by 3 years) Dandy Walker Malformation Dandy walker • Criteria: – high position of tentorium – dysgenesis/agenesis of vermis – cystic dilatation of fourth ventricle • commonly associated features: – hypoplasia of cerebellum – scalloping of inner table of occipital bone • associated abnormalities: – hydrocephalus 75% – dysgenesis of corpus callosum 25% – heterotropia 10% 2 1/16/2012 Etiology of Epilepsy: Developmental and Genetic Classification of Gray Matter Heterotropia Cortical Dysplasia 1. Secondary to abnormal neuronal and • displaced masses of nerve cells • Subependymal glial proliferation/apoptosis (gray matter) heterotropia (most • most common: small nest common) 2.
    [Show full text]
  • Description Treatment
    Description Megalencephaly, also called macrencephaly, is a condition in which an infant or child has an abnormally large, heavy, and usually malfunctioning brain. By definition, the brain weight is greater than average for the age and gender of the child. Head enlargement may be evident at birth or the head may become abnormally large in the early years of life. Megalencephaly is thought to be related to a disturbance in the regulation of cell production in the brain. In normal development, neuron proliferation - the process in which nerve cells divide to form new generations of cells - is regulated so that the correct number of cells is produced in the proper place at the appropriate time. In a megalencephalic brain, too many cells are produced either during development or progressively as part of another disorder, such as one of the neurofibromatoses or leukodystrophies. Symptoms of megalencephaly include delayed development, seizures, and corticospinal (brain cortex and spinal cord) dysfunction. Megalencephaly affects males more often than females. Unilateral megalencephaly or hemimegalencephaly is a rare condition that is characterized by the enlargement of one side of the brain. Children with this disorder may have a large, asymmetrical head accompanied by seizures, partial paralysis, and impaired cognitive development. Megalencephaly is different from macrocephaly (also called megacephaly or megalocephaly), which describes a big head, and which doesn’t necessarily indicate abnormality. Large head size is passed down through the generations in some families. Treatment There is no standard treatment for megalencephaly. Treatment will depend upon the disorder with which the megalencephaly is associated and will address individual symptoms and disabilities.
    [Show full text]
  • Mutation in Genes FBN1, AKT1, and LMNA: Marfan Syndrome, Proteus Syndrome, and Progeria Share Common Systemic Involvement
    Review Mutation in Genes FBN1, AKT1, and LMNA: Marfan Syndrome, Proteus Syndrome, and Progeria Share Common Systemic Involvement Tonmoy Biswas.1 Abstract Genetic mutations are becoming more deleterious day by day. Mutations of Genes named FBN1, AKT1, LMNA result specific protein malfunction that in turn commonly cause Marfan syndrome, Proteus syndrome, and Progeria, respectively. Articles about these conditions have been reviewed in PubMed and Google scholar with a view to finding relevant clinical features. Precise keywords have been used in search for systemic involvement of FBN1, AKT1, and LMNA gene mutations. It has been found that Marfan syndrome, Proteus syndrome, and Progeria commonly affected musculo-skeletal system, cardiovascular system, eye, and nervous system. Not only all of them shared identical systemic involvement, but also caused several very specific anomalies in various parts of the body. In spite of having some individual signs and symptoms, the mutual manifestations were worth mentio- ning. Moreover, all the features of the mutations of all three responsible genes had been co-related and systemically mentioned in this review. There can be some mutual properties of the genes FBN1, AKT1, and LMNA or in their corresponding proteins that result in the same presentations. This study may progress vision of knowledge regarding risk factors, patho-physiology, and management of these conditions, and relation to other mutations. Keywords: Genetic mutation; Marfan syndrome; Proteus syndrome; Progeria; Gene FBN1; Gene AKT1; Gene LMNA; Musculo-skeletal system; Cardiovascular system; Eye; Nervous system (Source: MeSH, NLM). Introduction Records in human mutation databases are increasing day by 5 About the author: Tonmoy The haploid human genome consists of 3 billion nucleotides day.
    [Show full text]
  • Megalencephaly and Macrocephaly
    277 Megalencephaly and Macrocephaly KellenD.Winden,MD,PhD1 Christopher J. Yuskaitis, MD, PhD1 Annapurna Poduri, MD, MPH2 1 Department of Neurology, Boston Children’s Hospital, Boston, Address for correspondence Annapurna Poduri, Epilepsy Genetics Massachusetts Program, Division of Epilepsy and Clinical Electrophysiology, 2 Epilepsy Genetics Program, Division of Epilepsy and Clinical Department of Neurology, Fegan 9, Boston Children’s Hospital, 300 Electrophysiology, Department of Neurology, Boston Children’s Longwood Avenue, Boston, MA 02115 Hospital, Boston, Massachusetts (e-mail: [email protected]). Semin Neurol 2015;35:277–287. Abstract Megalencephaly is a developmental disorder characterized by brain overgrowth secondary to increased size and/or numbers of neurons and glia. These disorders can be divided into metabolic and developmental categories based on their molecular etiologies. Metabolic megalencephalies are mostly caused by genetic defects in cellular metabolism, whereas developmental megalencephalies have recently been shown to be caused by alterations in signaling pathways that regulate neuronal replication, growth, and migration. These disorders often lead to epilepsy, developmental disabilities, and Keywords behavioral problems; specific disorders have associations with overgrowth or abnor- ► megalencephaly malities in other tissues. The molecular underpinnings of many of these disorders are ► hemimegalencephaly now understood, providing insight into how dysregulation of critical pathways leads to ►
    [Show full text]
  • Polymicrogyria (PMG) ‘Many–Small–Folds’
    Polymicrogyria Dr Andrew Fry Clinical Senior Lecturer in Medical Genetics Institute of Medical Genetics, Cardiff [email protected] Polymicrogyria (PMG) ‘Many–small–folds’ • PMG is heterogeneous – in aetiology and phenotype • A disorder of post-migrational cortical organisation. PMG often appears thick on MRI with blurring of the grey-white matter boundary Normal PMG On MRI PMG looks thick but the cortex is actually thin – with folded, fused gyri Courtesy of Dr Jeff Golden, Pen State Unv, Philadelphia PMG is often confused with pachygyria (lissencephaly) Thick cortex (10 – 20mm) Axial MRI 4 cortical layers Lissencephaly Polymicrogyria Cerebrum Classical lissencephaly is due Many small gyri – often to under-migration. fused together. Axial MRI image at 7T showing morphological aspects of PMG. Guerrini & Dobyns Malformations of cortical development: clinical features and genetic causes. Lancet Neurol. 2014 Jul; 13(7): 710–726. PMG - aetiology Pregnancy history • Intrauterine hypoxic/ischemic brain injury (e.g. death of twin) • Intrauterine infection (e.g. CMV, Zika virus) TORCH, CMV PCR, [+deafness & cerebral calcification] CT scan • Metabolic (e.g. Zellweger syndrome, glycine encephalopathy) VLCFA, metabolic Ix • Genetic: Family history Familial recurrence (XL, AD, AR) Chromosomal abnormalities (e.g. 1p36 del, 22q11.2 del) Syndromic (e.g. Aicardi syndrome, Kabuki syndrome) Examin - Monogenic (e.g. TUBB2B, TUBA1A, GPR56) Array ation CGH Gene test/Panel/WES/WGS A cohort of 121 PMG patients Aim: To explore the natural history of PMG and identify new genes. Recruited: • 99 unrelated patients • 22 patients from 10 families 87% White British, 53% male ~92% sporadic cases (NB. ascertainment bias) Sporadic PMG • Array CGH, single gene and gene panel testing - then a subset (n=57) had trio-WES.
    [Show full text]
  • Level Estimates of Maternal Smoking and Nicotine Replacement Therapy During Pregnancy
    Using primary care data to assess population- level estimates of maternal smoking and nicotine replacement therapy during pregnancy Nafeesa Nooruddin Dhalwani BSc MSc Thesis submitted to the University of Nottingham for the degree of Doctor of Philosophy November 2014 ABSTRACT Background: Smoking in pregnancy is the most significant preventable cause of poor health outcomes for women and their babies and, therefore, is a major public health concern. In the UK there is a wide range of interventions and support for pregnant women who want to quit. One of these is nicotine replacement therapy (NRT) which has been widely available for retail purchase and prescribing to pregnant women since 2005. However, measures of NRT prescribing in pregnant women are scarce. These measures are vital to assess its usefulness in smoking cessation during pregnancy at a population level. Furthermore, evidence of NRT safety in pregnancy for the mother and child’s health so far is nebulous, with existing studies being small or using retrospectively reported exposures. Aims and Objectives: The main aim of this work was to assess population- level estimates of maternal smoking and NRT prescribing in pregnancy and the safety of NRT for both the mother and the child in the UK. Currently, the only population-level data on UK maternal smoking are from repeated cross-sectional surveys or routinely collected maternity data during pregnancy or at delivery. These obtain information at one point in time, and there are no population-level data on NRT use available. As a novel approach, therefore, this thesis used the routinely collected primary care data that are currently available for approximately 6% of the UK population and provide longitudinal/prospectively recorded information throughout pregnancy.
    [Show full text]
  • CONGENITAL ABNORMALITIES of the CENTRAL NERVOUS SYSTEM Christopher Verity, Helen Firth, Charles Ffrench-Constant *I3
    J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.74.suppl_1.i3 on 1 March 2003. Downloaded from CONGENITAL ABNORMALITIES OF THE CENTRAL NERVOUS SYSTEM Christopher Verity, Helen Firth, Charles ffrench-Constant *i3 J Neurol Neurosurg Psychiatry 2003;74(Suppl I):i3–i8 dvances in genetics and molecular biology have led to a better understanding of the control of central nervous system (CNS) development. It is possible to classify CNS abnormalities Aaccording to the developmental stages at which they occur, as is shown below. The careful assessment of patients with these abnormalities is important in order to provide an accurate prog- nosis and genetic counselling. c NORMAL DEVELOPMENT OF THE CNS Before we review the various abnormalities that can affect the CNS, a brief overview of the normal development of the CNS is appropriate. c Induction—After development of the three cell layers of the early embryo (ectoderm, mesoderm, and endoderm), the underlying mesoderm (the “inducer”) sends signals to a region of the ecto- derm (the “induced tissue”), instructing it to develop into neural tissue. c Neural tube formation—The neural ectoderm folds to form a tube, which runs for most of the length of the embryo. c Regionalisation and specification—Specification of different regions and individual cells within the neural tube occurs in both the rostral/caudal and dorsal/ventral axis. The three basic regions of copyright. the CNS (forebrain, midbrain, and hindbrain) develop at the rostral end of the tube, with the spinal cord more caudally. Within the developing spinal cord specification of the different popu- lations of neural precursors (neural crest, sensory neurones, interneurones, glial cells, and motor neurones) is observed in progressively more ventral locations.
    [Show full text]
  • Classification of Congenital Abnormalities of the CNS
    315 Classification of Congenital Abnormalities of the CNS M. S. van der Knaap1 A classification of congenital cerebral, cerebellar, and spinal malformations is pre­ J . Valk2 sented with a view to its practical application in neuroradiology. The classification is based on the MR appearance of the morphologic abnormalities, arranged according to the embryologic time the derangement occurred. The normal embryology of the brain is briefly reviewed, and comments are made to explain the classification. MR images illustrating each subset of abnormalities are presented. During the last few years, MR imaging has proved to be a diagnostic tool of major importance in children with congenital malformations of the eNS [1]. The excellent gray fwhite-matter differentiation and multi planar imaging capabilities of MR allow a systematic analysis of the condition of the brain in infants and children. This is of interest for estimating prognosis and for genetic counseling. A classification is needed to serve as a guide to the great diversity of morphologic abnormalities and to make the acquired data useful. Such a system facilitates encoding, storage, and computer processing of data. We present a practical classification of congenital cerebral , cerebellar, and spinal malformations. Our classification is based on the morphologic abnormalities shown by MR and on the time at which the derangement of neural development occurred. A classification based on etiology is not as valuable because the various presumed causes rarely lead to a specific pattern of malformations. The abnor­ malities reflect the time the noxious agent interfered with neural development, rather than the nature of the noxious agent. The vulnerability of the various structures to adverse agents is greatest during the period of most active growth and development.
    [Show full text]
  • Unilateral Megalencephaly. Correlates
    523 Unilateral Megalencephaly: Correlation of MR Imaging and Pathologic Characteristics A. James Barkovich 1 Unilateral megalencephaly is a rare and poorly understood malformation resulting in Sylvester H. Chuang2 the enlargement of all or part of a cerebral hemisphere. The clinical and radiologic features of 12 patients with unilateral megalencephaly are presented; pathologic cor­ relation was available in four. All patients had seizures and developmental delay. Two were in congestive heart failure as a result of arteriovenous shunting through the abnormal hemisphere. The affected hemispheres showed a wide spectrum of involve­ ment. Anomalies of neuronal migration were present, and there was a roughly inverse correlation between the severity of hemispheric involvement and the magnitude of enlargement. This correlation is explained via a proposed mechanism of a mild hemi­ spheric insult in the middle-to-late second trimester. One patient had an extremely anomalous hemisphere that did not have characteristics of a neuronal migration anomaly and may have been a hamartomatous malformation. Our correlation of the clinical, radiologic, and pathologic features of unilateral mega­ lencephaly, together with a theory of pathogenesis, should help elucidate this rare malformation. AJNR 11:523-531, May{June 1990 Unilateral megalencephaly is a rare anomaly of the brain in which all or part of one hemisphere is enlarged in the absence of somatic hemihypertrophy [1- 8). We recently reviewed the imaging studies of 12 patients with this anomaly; histologic material was available in four of these. In this report, we describe the clinical , radiologic, and pathologic features of this anomaly and relate the pathologic anatomy to a proposed theory of pathogenesis.
    [Show full text]
  • Supratentorial Brain Malformations
    Supratentorial Brain Malformations Edward Yang, MD PhD Department of Radiology Boston Children’s Hospital 1 May 2015/ SPR 2015 Disclosures: Consultant, Corticometrics LLC Objectives 1) Review major steps in the morphogenesis of the supratentorial brain. 2) Categorize patterns of malformation that result from failure in these steps. 3) Discuss particular imaging features that assist in recognition of these malformations. 4) Reference some of the genetic bases for these malformations to be discussed in greater detail later in the session. Overview I. Schematic overview of brain development II. Abnormalities of hemispheric cleavage III. Commissural (Callosal) abnormalities IV. Migrational abnormalities - Gray matter heterotopia - Pachygyria/Lissencephaly - Focal cortical dysplasia - Transpial migration - Polymicrogyria V. Global abnormalities in size (proliferation) VI. Fetal Life and Myelination Considerations I. Schematic Overview of Brain Development Embryology Top Mid-sagittal Top Mid-sagittal Closed Neural Tube (4 weeks) Corpus Callosum Callosum Formation Genu ! Splenium Cerebral Hemisphere (11-20 weeks) Hemispheric Cleavage (4-6 weeks) Neuronal Migration Ventricular/Subventricular Zones Ventricle ! Cortex (8-24 weeks) Neuronal Precursor Generation (Proliferation) (6-16 weeks) Embryology From ten Donkelaar Clinical Neuroembryology 2010 4mo 6mo 8mo term II. Abnormalities of Hemispheric Cleavage Holoprosencephaly (HPE) Top Mid-sagittal Imaging features: Incomplete hemispheric separation + 1)1) No septum pellucidum in any HPEs Closed Neural
    [Show full text]
  • MR Imaging of N Euronal Migration Anomaly
    대 한 방 사 선 의 학 회 지 1991; 27(3) : 323~328 Journal of Korean Radiological Society. May. 1991 MR Imaging of N euronal Migration Anomaly Hyun Sook Hong, M.D., Eun Wan Choi, M.D., Dae Ho Kim, M.D., Moo Chan Chung, M.D., Kuy Hyang Kwon, M.D., Ki Jung Kim, M.D. Department o[ RadíoJogy. Col1ege o[ Medícine. Soonchunhyang University patients ranged in age from 5 months to 42 years with Introduction a mean of 16 years. The mean age was skewed by 2 patients with schizencephaly who were 35 and 42 Abnormalities of neuronal migration Sl re years old. characterized by anectopic location of neurons in the MR was performed with a 0:2T permanent type cerebral cortex (1-9). This broad group of anomalies (Hidachi PRP 20). Slice thickness was 5mm with a includes agyria. pachygyria. schizencephaly. 2.5mm interslice gap or 7.5mm thickness. Spin echo unilateral megalencephaly. and gray matter axial images were obtained. including Tl weighted hcterotopia. Patients with this anomaly present images (TIWI) with a repetition time (TR) of clinically with a variety of symptoms which are pro­ 400-500ms and echo time (TE) of 25-40ms. in­ portional to the extent of the brain involved. These termediate images of TR/TE 2000/38. and T2 abnormalities have been characterized pathologically weighted images (T2Wl) with a TR/TE of 2000/110. in vivo by sonography and CT scan (2. 3. 10-14. Occasionally. sagittal and coronal images were ob­ 15-21). tained. Gd-DTPA enhanced Tl WI were 려 so obtain­ MR appears to be an imaging technique of choice ed in 6 patients.
    [Show full text]