- Chiari Malformation Video
- What are Chiari Malformations?
- What is Chiari 1 Malformation?
- Whats is Chiari 2 Malformation?
- Whats is Chiari 3 Malformation?
- What is Chiari 4 Malformation?
- What is Chiari Type 0 and Chiari Type 1.5 ?
What are Chiari Malformations?
- Chiari Malformations are a group of abnormalities which involve the rhombencephalon which is also called as Hind brain and the contents of the CV junction.
- We have 6 types of Chiari malformations
What is Chiari 1 Malformation?
- In the MRI below, the foramen magnum has two points, the Basion and the opisthion. A line joining these points is called McRae’s line. The herniation of tonsils and other brain structures is measured from this line.
- 5-mm or more caudal displacement of the cerebellar tonsils inferior to the foramen magnum
- This herniation and compression restricts normal CSF flow across the craniocervical junction
- Commonly associated findings are cervical syringomyelia(50-75%) and, on occasion, hydrocephalus (10%)
What is Chiari 2 Malformation?
- In Chiari 2 Malformation there is a greater amount of tissue that extends into the spinal canal compared to the chiari 1 malformation
- There is characteristic displacement of the medulla, fourth ventricle, and cerebellum through the foramen magnum.
- almost all neonatal patients with Chari II have a myelomeningocele
- Can have tectal beaking
What is Chiari 3 Malformation?
- Extremely rare
- Characterized by low occipital and high cervical encephalocele
- There is herniation of posterior fossa contents, that is, the cerebellum and/or the brainstem, occipital lobe, and fourth ventricle.
What is Chiari 4 Malformation?
- This is characterized by marked cerebellar hypoplasia or aplasia and tentorial hypoplasia.
- There is no hindbrain herniation.
- No hydrocephalus
What is Chiari type 0 and Chiari Type 1.5 ?
- syringohydromyelia without hindbrain herniation that respond to posterior fossa decompression (CSF flow across foramen magnum impaired)
- Severe form of Chiari
- Entire cervicomedullary junction (and obex) is situated below the foramen magnum