Features of Chiari Malformations in Children

Chiari Type Anatomical Anomaly Frequency of Hydrocephalus Associated CNS Anoimalies
I Tonsillar herniation ≥5 mm below plane of foramen magnum with moderate frequency of syringomyelia Low Multiple
II Caudal herniation of vermis, brainstem, and fourth ventricle with high frequency of syringomyelia High Associated with myelomeningocele and multiple brain anomalies
III Occipital encephalocele containing dysmorphic cerebellum and brainstem N/A N/A
IV Hypoplasia or aplasia of cerebellum N/A N/A

 

Anomalies associated with Chiari I malformation

  • Syndromic craniosynostosis: These disorders include Apert’s and Crouzon’s syndromes
  • Endocrinopathies: These include achondroplasia, acromegaly growth hormone deficiency, and osteopetrosis or Paget’s disease.
  • Neurocutaneous disorders: These disorders include NF1, acanthosis nigricans, blue rubber bleb nevus syndrome, giant congenital melanocytic nevi, LEOPARD syndrome, and Waardenburg syndrome.
  • Beckwith-Wiedemann syndrome
  • Ehlers-Danlos syndrome
  • Craniocervical anomalies: These include basilar invagination, atlantoaxial assimilation and Klippel-Feil syndrome.
  • Acquired tonsillar descent: Elevation in ICP due to conditions such as brain tumors and hydrocephalus may cause acquired tonsillar descent (56).