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  • Pietro D'Urso

Chiari Malformation

Updated: Sep 29



A Chiari malformation is a condition in which some of the brain tissue (cerebellar tonsils, cerebellum, brain stem and/or part of the fourth ventricle) pushes on to the spinal canal. This can occur when the skull is too small or misshapen.


This can result in the signals from the brain being blocked and can also lead to a build up of cerebrospinal fluid in the spine or the brain. Although Chiari malformations can cause symptoms for patients, many people can also live with the condition without knowing. In recent years the number of people that have imaging test at hospital has gone up, this has also lead to an increase in the number of people that are diagnosed with a Chiari malformation, even if it does not cause any symptoms.


Symptoms can vary depending on the severity and type of Chiari malformation that you have. There are three types of Chiari malformation, Chiari I and Chiari II are the most common, however some doctors recognise a Chiari IIII.

Chiari I

  • This type of malformation does not usually cause any symptoms and is usually not known about until later in life

  • Common symptoms can include impulse headaches, problems with vision and balance

  • Chiari I malformations occur when part of the skull is too small or deformed, causing the brain to become cramped. This leads to the lower part of the brain (cerebellar tonsils) being pushed into the upper part of the spinal canal.

Chiari II

  • Chiari II is often present at birth and is related to an open myelomeningocele/spina bifida. This is different to Chiari I, as a larger portion of the brain extends into the spinal canal.

  • This presents with feeding/swallowing, changes in breathing, weakness in the arms and quick downward eye movements

Chari III

  • This is a rare form of Chari, however is very severe. This occurs when a part of the brain protrudes through an opening in the skull called an encephalocele. Chiari III can cause neurological problems and is often diagnosed at birth or in pregnancy.

The treatment for a Chiari malformation depends on the type and the symptoms. If you do not present with any symptoms then it is likely that nothing will be done and you will be asked to attend regular examinations to see if there has been any changes.

If it is causing symptoms it will usually be treated with surgery. The purpose of surgery is to stop the condition from getting worse, while also trying to reduce the symptoms that the patient may be experiencing. Your consultant will talk through the pro's and con's of surgery before you go ahead with the surgery.


This article is intended to inform and give insight but not treat, diagnose or replace the advice of a doctor. Always seek medical advice with any questions regarding a medical condition.

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