A Chiari malformation is a problem
in which a part of the brain at the rear of the skull bulges through a normal opening
(foramen magnum) in the skull where it joins the spinal canal. This puts pressure
parts of the brain and spinal cord. It can cause mild to severe symptoms. In most
the problem is present at birth (congenital).
There are four main types of Chiari
malformations (types I, II, III, and IV). Type I is the most common. This article
about type II. In this type, two parts of the brain (the cerebellum and brainstem)
through the foramen magnum.
This problem can happen in newborns
who have spina bifida or spinal myelomeningoceles. A myelomeningocele is when part
the spinal cord and meninges grow outside the body instead of inside.
A common problem with type II malformations is too much spinal fluid in the brain
(hydrocephalus). The extra fluid puts more pressure on the brain. The bones of the
skull expand to a larger-than-normal size.