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Chiari malformation (CM) is a structural deformity where the skull’s shape pushes the brain’s cerebellum out of the skull and into the spinal canal. The cerebellum is the portion of the brain located behind the brain stem, right where the spinal cord meets the brain.

CM blocks the brain’s vital signals to and from the rest of the body. It can also be responsible for fluid buildup in the brain and spinal cord, which leads to a variety of neurological symptoms.

There are 5 types of Chiari Malformations:

Type 0: Type 0 is a very minimal form of CM. There are little to no physical changes to the cerebellum or its lower portions, which are called tonsils. However, it may cause headaches.

Type 1: Type 1 is the most common form of CM. It involves the lower portion of the cerebellum and develops while the skull and brain are still growing. However, symptoms may not present themselves until later in life, usually around tween or adult years.

Type 2: Type 2 is also referred to as Classic CM. Involving both the cerebellum and the brain stem, this condition occurs when the backbone and spinal canal don’t close normally at birth.

Type 3: Type 3 is a rare and more serious form of CM. In this condition, brain tissue extends into the spinal cord, leading to severe neurological defects and sometimes life-threatening complications.

Type 4: Type 4 occurs when there is an underdeveloped cerebellum and is usually fatal in infancy.


Typically, the more brain tissue that pushes through the spine, the more severe symptoms of CM will be. Following that logic, Type 0 will have the least amount of symptoms while Type 4 will have the most severe symptoms.

Typical symptoms of CM include:

  • Loss of coordination
  • Balance issues
  • Vision and speech issues
  • Neck pain
  • Numbness in the extremities
  • Hearing loss
  • Weakness in the upper body


Most cases of CM develop during the fetal stages and are known as congenital CM. There are a few factors during pregnancy that place someone at a larger risk for developing CM. These include:

  • Genetic mutations
  • Lack of proper vitamins
  • Infection or high fever
  • Exposure to hazardous chemicals or recreational drugs


Treatment of CM will depend on its type, severity and symptoms. Sometimes medication is enough to manage the symptoms of CM, while other times, surgery may be necessary. Surgery is typically only considered if there is severe interference with the nervous system.

For a comprehensive evaluation from the experts at Brain2Spine Institute, call 727-828-8400.

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