Alterations of Neurologic Function in Children

Development of Nervous System in Children

  • Develops from embryonic ectoderm, beginning around day 40.
  • By day 175, the brain has developed all parts.
  • Genetic and environmental factors significantly affect neural development.
  • Head growth occurs at suture lines and fontanelles (soft spots).

Structural Malformations

  • Responsible for 75% of fetal deaths and 40% of deaths in the first year.
  • Most CNS malformations are defects of neural tube closure.
    • Examples include Arnold-Chiari type II malformation and tethered cord syndrome.

Neural Tube Defects

  • Categorized by anterior midline and posterior defects.
  • Defects include:
    • Cyclopia
    • Spina bifida (vertebrae fail to close), including:
    • Anencephaly
    • Encephalocele
    • Meningocele
    • Myelomeningocele
    • Chiari II malformation (Arnold-Chiari malformation)
    • Tethered cord syndrome

Spina Bifida Occulta

  • Vertebral defect with no visible exposure of meninges or spinal cord.
  • No neurologic dysfunction; spinal cord and spinal nerves are normal.

Myelomeningocele

  • A saclike cyst containing meninges, spinal fluid, and a portion of the spinal cord with its nerves.
  • Located in the lumbar and lumbosacral regions.

Craniosynostosis

  • Premature closure of one or more cranial sutures.
    • Prevents growth perpendicular to the suture line.
    • Results in Plagiocephaly (asymmetric shape of skull).

Malformation of Brain Development

  • Microcephaly: defect in brain growth as a whole.
    • True (primary) microcephaly.
    • Secondary (acquired) microcephaly.
  • Cortical dysplasia: defect in brain development; embryonic neurons migrate to the wrong places.
  • Dandy-Walker malformation: congenital defect of the cerebellum with a large posterior fossa cyst.
  • Congenital hydrocephalus: increased CSF pressure, enlargement of ventricles, caused by blockage, CSF production imbalance, or reduced reabsorption.

Encephalopathies

  • Static (nonprogressive) encephalopathies: neurologic condition caused by fixed lesion without active disease.
    • Cerebral palsy: includes pyramidal/spastic, extrapyramidal/nonspastic, dystonic, and ataxic types.
  • Inherited metabolic disorders:
    • Defects in amino acid metabolism, e.g., phenylketonuria (PKU).
    • Defects in lipid metabolism, e.g., Lysosomal storage diseases (Tay-Sachs disease).

Phenylketonuria (PKU)

  • Blocked metabolic pathway leads to abnormal metabolites.
    • Results in central nervous system damage, mental retardation, hyperactivity, seizures.

Intoxications of the CNS

  • Drug-induced encephalopathies from ingestion or overdose.
    • Lead poisoning and fetal neurotoxicity with maternal lead exposure.

Infections of the CNS

  • Meningitis: aseptic, bacterial, viral.
  • Meningoencephalitis: meningitis and encephalitis both present.
  • Viral encephalitis.

Cerebrovascular Disease

  • Perinatal stroke and childhood stroke.
    • Ischemic (occlusive) or Hemorrhagic.
    • Moyamoya disease.
  • Epilepsy: diagnosed when a child has more than one unprovoked seizure.
  • Seizures: neurologic, systemic, febrile (benign).

Childhood Tumors

  • Brain tumors: Medulloblastoma, Atypical teratoid rhabdoid tumors, CNS primitive neuroectodermal tumors, High-grade gliomas.
  • Embryonal tumors: Neuroblastoma, Retinoblastoma (inherited/acquired).

Neuroblastoma

  • Embryonal tumor of the sympathetic nervous system.