After having a conversation with a former client, I have decided to spend some time over the next few days to blog about a brain condition know as Chiari malformation. I hope to be able to share information about this developmental abnormality with the readers of my blog who are unaware of this issue, and what it means.

Chiari malformation is a developmental anomaly at the base of the brain which results in the downward displacement of some of the brain’s structures into the spinal canal. The lower most part of the brain is the cerebellum and brainstem. This is the area just at the base of the skull which attaches to the spinal cord. This area is called the posterior fossa. The cerebellum is made up of three major lobes which are composed of nerve fibers connecting to the brainstem. There are two small portions of cerebellar tissue, called the cerebellar tonsils, which normally lie within the posterior fossa. A more detailed explination of the information above can be found here.

Dr. Chiari, back in 1891, first identified the Chiari type I malformation. The problem occurs when the posterior fossa is not properly formed and the brainstem, instead of sitting properly in the posterior fossa, is displaced downward, causing pressure on this part of the brain and the spinal cord. There is also an obstruction of the normal flow of cerebral spinal fluid through this area because the tonsils of the cerebellum are stuffed into the funnel.