National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Chiari malformation

Chiari malformations are structural defects in the cerebellum, the part of the brain that controls balance. When the indented bony space at the lower rear of the skull is smaller than normal, the cerebellum and brainstem can be pushed downward. The resulting pressure on the cerebellum can block the flow of cerebrospinal fluid (the liquid that surrounds and protects the brain and spinal cord) and can cause a range of symptoms including dizziness, muscle weakness, numbness, vision problems, headache, and problems with balance and coordination.[1] The exact cause is still unknown. In some cases of Chiari Malformation type 1, genetic factors may be involved.[2] Treatment may require surgery.[1]

There are four types of Chiari malformations classified according to the degree of severity, with type 1 being the most common and least severe:

Chiari malformation type 1
Chiari malformation type 2
Chiari malformation type 3
Chiari malformation type 4

Some researchers add a type 0 to the classification, which is characterized by no or very little herniation of the cerebellum.[1]
Last updated: 8/11/2017

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Chiari malformation. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Chiari malformation. Click on the link to view a sample search on this topic.

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  1. Chiari Malformation Fact Sheet. National Institute of Neurological Disorders and Stroke (NINDS). June 2013; https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Chiari-Malformation-Fact-Sheet.
  2. Chiari Malformation. Mayo Clinic. 2013; http://www.mayoclinic.org/diseases-conditions/chiari-malformation/basics/risk-factors/con-20031115.