Chiari malformation is considered a congenital condition, although acquired forms of the condition have been diagnosed. A German pathologist, Professor Hans Chiari, first described abnormalities of the brain at the junction of the skull with the spine in the 1890s. He categorized these in order of severity; types I, II, III, and IV. The term "Arnold-Chiari" was latter applied to the Chiari type II malformation. These malformations, along with syringomyelia and hydromyelia, two closely associated conditions, are described below.

The cerebellum controls the coordination of motion, and is normally located inside the base of the skull, in what is referred to as the posterior fossa. Usually, the cerebellum is composed of two lateral halves or hemispheres, and a narrow central portion between these hemispheres, known as the vermis. Along the under surface of the hemispheres, there are two small protrusions called the tonsils. The fourth ventricle is a cerebrospinal fluid (CSF) filled space located in front of the cerebellum (and behind the brainstem). All of these structures are located just above the foramen magnum, the largest opening at the base of the skull through which the spinal cord enters and connects to the brainstem.

Chiari Malformation Overview

  • Prevalence

  • Types of Malformations

  • Treatment

  • Diagnosis

  • Syringomyelia/Hydromyelia

  • Symptoms

  • Surgery

  • Outcome


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