Congenital hydrocephalus 

• Definition - progressive ventricular enlargement noted either on fetal echo and/or apparent in the first days of life.
  • excessive formation of CSF (RARE - choroid plexus tumors)
  • decreased reabsorption of CSF
  • obstruction of CSF flow

• Clinical features
  • enlarged head
  • large anterior fontanel, separated sutures
  • other organ system anomalies
  • flexion deformity of the thumbs (50% of X-linked aqueductal stenosis)
  • chorioretinitis
    
    
• Etiologies
  • Aqueductal stenosis
  • myelomeningocele: Arnold-Chiari malformation
  • "Communicating hydrocephalus"
  • Dandy-Walker malformation
  • Intraventricular hemorrhage
  • Tumor
  • Infection
    
    
• "fetal hydrocephalus" - outcome determined primarily on anomalies
  • accompanying major extraneural anomalies - 40-50%
  • major CNS anomalies - 60-65%
  • either extraneural or CNS anomalies (or both) - 80%
    
    
• Neuro imaging
  • serial ultrasounds either in utero and/or postnatally - following the rate of ventricular enlargement (especially in IVH)
  • MRI (or CT) to
    • measure cortical mantle
    • look for other CNS anomalies
    • etiology
      
      
• Management
  • VP shunt in nearly all cases except those where other birth defects may preclude survival (comfort and care issues present even in poor prognosis).
    
    
• Prognosis
  • Etiology dependent ( communicating and Arnold Chiari often have normal IQ; Dandy -Walker and Aqueductal Stenosis are often retarded)
  • presence of other brain anomalies
  • If no etiology is found - 40-50% are normal in follow-up.
    
    
• Etiologies - details
  • Aqueductal stenosis
    • up to 66% of cases of congenital hydrocephalus
    • 75% etiology unknown
    • ultrasound shows bilateral ventriculomegally along with a dilated third ventricle.
    • X-linked aqueductal stenosis
      1. incidence 17-36 per 1,000,000 males
      2. not always seen on prenatal ultrasound
      3. variable spectrum
      4. Xq28
      5. hydrocephalus
      6. macrocephaly
      7. adducted thumbs
      8. spasticity
      9. mental retardation
      10. cerebral malformations (agenesis of the corpus callosum)
          
  • Arnold-Chiari malformation
    • causes hydrocephalus and brainstem dysfunction in children with neural tube defects
    • Medulla and fourth ventricle are displaced into the upper cervical canal
    • lower cerebellum is inferiorly displaced into the foramen magnum.
    • 40-75% have associated aqueductal stenosis
    • can be associated with brainstem dysfunction (feeding problems, stridor, apnea)
    • Many patients have associated abnormalities with the cerebral cortex
    • Despite these problems 75-85% of children have normal intelligence
      
  • "Communicating hydrocephalus"
    • no anatomic obstruction to CSF flow
    • Imbalance of secretion and absorption of CSF
    • Prognosis generally favorable
      
  • Dandy-Walker syndrome
    • 5-10% of congenital hydrocephalus cases.
    • clinical features
      1. cystic dilation of the fourth ventricle
      2. complete or partial agenesis of the cerebellum
      3. hydrocephalus
    • 20-30% have non-CNS malformations
    • 70% or more have other CNS malformations
    • Outcome
      1. fetal or neonatal presentation generally indicates unfavorable outcome
      2. 40% die
      3. 75% of survivors have cognitive deficits
      4. If no associated anomalies (brain or systemic), or if presents at an older age, then prognosis is markedly better.