Chiari malformation

A Chiari malformation, formerly known as an Arnold-Chiari malformation, occurs when the lower section of the brain protrudes into the spinal canal. There are four primary types, with type 1, referred to as Chiari I, being the most prevalent. In individuals with Chiari I, the lowest part of the brain extends into the spinal canal. This can lead to pressure on the brainstem and spinal cord, as well as hinder the flow of cerebrospinal fluid. This page specifically addresses Chiari I malformations.