LISSENCEPHALY
 
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    LISSENCEPHALY

     

    DEFINITION:

    A disorder of neuronal migration characterized by the absence of sulcation of the cerebral hemispheres resulting in a "smooth brain".

    EPIDEMIOLOGY:

    • incidence: ?
    • age of onset:
      • infancy to childhood
    • risk factors:
      • an in utero insult to the developing brain (see below)
      • clinical subtypes of lissencephaly have various inheritance patterns
    • associated anomalies:
      • other migration disorders
        • gray matter heterotopias
        • macrogyri or micropolygyri
      • nonneural congenital anomalies
        • cataracts & other ocular anomalies
        • congenital heart disease
        • cryptorchidism
        • duodenal atresia
        • renal agenesis
        • polydactyly or syndactyly

    PATHOGENESIS:

    1. Background

    • an insult before 12 weeks gestational age prevents successive waves of migrating neurons from reaching the cerebral cortex resulting in agyria and a thickened cortical surface -> smooth cerebral cortical surface

    2. Insults

    1. Infections

    • congenital CMV infection

    2. Genetic or Chromosomal Disorders

    • autosomal recessive (25% recurrence rate)
    • syndromes
      • Miller-Dieker Syndrome
      • Walker-Warburg Syndrome (WWS)

    TYPES:

    1. Type I (Classic) Lissencephaly

    • pathologically distinct from Type II
    • associated with various syndromes
      • Miller-Dieker Syndrome
    • strong association between Miller-Dieker syndrome and terminal
    • 17p deletion

    2. Type II Lissencephaly

    • associated with various syndromes
      • Walker-Warburg, Warburg, or HARD+/-E Syndrome

    CLINICAL FEATURES:

    1. Neurologic Manifestations

    • infantile hypotonia
    • seizure disorder
      • infantile spasms
      • Lennox-Gastaut syndrome
      • massive myoclonus
    • motor dysfunction
      • hypotonia
      • rigidity and opisthotonos
    • severe mental retardation
    • microcephaly
    • developmetnal delay

    2. Other Manifestations

    1. Ocular Manifestations

    • hypoplasia of optic nerve
    • microphthalmia

    2. Miller-Dieker Syndrome

    • dysmorphic features:
      • anteverted nostrils
      • "carp mouth"
      • high, wrinkled forehead
      • micrognathia
      • slanted palpebral fissures
    • others:
      • SGA, polyhydramnios, failure to thrive
      • apnea and bradycardia, weak cry
      • hirsutism

    3. HARD+/-E Syndrome (Warburg or Walker-Warburg Syndrome)

    • H - hydrocephalus
    • A - agyria
    • R - retinal Dysplasia
    • E - encephalocoele

    INVESTIGATIONS:

    1. Imaging Studies

    1. CT/MRI

  • 1. Cerebral Cortex
    • smooth cerebral cortex without secondary sulci
    • a few primary fissures and sulci may be present
    • symmetric enlargement of ventricles
    • the structural pattern of the cerebral hemispheres and ventricles resemble the 3-4 month old fetal brain

    • MANAGEMENT:

    1. Team Approach

    • periodic multidisciplinary follow-up
      • Paediatrics, Neurology, Ortho, OT, PT

    2. Supportive

    • anticonvulsants
    • genetic counselling

    INTERNET LINKS:

    Lissencephaly Network Home Page

     

     

    Pediatric Database - LISSENCEPHALY

     

    Pediatric Organization - Pedbase [at] Gmail.com

     
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