Please explain arnold chiari syndrome.?

Complicated: The lower back of skull, where it joint your neck has a space called posterior fossa could be small---so the cerebellum which is the coordination center can be pushed down through the hole of skull leading to dizziness, headache, incoordination, numbness it has several degrees and present different age--most serious in children--but adult can have type i, which may need operation consult neurosurgery.

Now called Chiari ll: A retrospective look has taken arnold's name away. There are two main types of chiari malformations that are not really related to each other. Chiari 1 affects adults and is the result of a small brain compartment that forces the cerebellar tonsils through the foramen magnum. Chiari 11 affects children from birth and is associated with a myelomeningocele at birth. The brainstem itself is altered.