Arnold-Chiari syndrome is a defect in the formation of the cerebellum (the small, bottom portion of the brain) and brainstem. This defect can prevent the passage of blood from the brain into the spinal canal. Arnold-Chiari syndrome is usually accompanied by a myelomeningocele, which is a form of spina bifida . There are four types of Chiari Syndrome, with different degrees of severity. Type 2 is the one that is associated with spina bifida.

Brain Stem and Cerebellum

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Arnold-Chiari syndrome occurs during brain development before birth. The indented bony space in the lower rear of the skull is smaller than normal, so the cerebellum and brainstem are pushed downward. The reason the brain does not develop normally is not well understood.

Risk Factors

The following conditions are commonly associated with Arnold-Chiari syndrome, but are not thought to be a cause of the disorder:


Symptoms exhibited in infants may include:

  • Vomiting
  • Mental impairment
  • Weakness
  • Paralysis of the limbs

Symptoms in adolescents are usually milder and may include:

  • Dizziness
  • Fainting
  • Weakness of the legs
  • Headaches
  • Double vision
  • Deafness
  • Swelling of the optic nerve region
  • Rapid eye movement
  • Lack of muscular coordination
  • Uncontrolled shaking or trembling
  • Walking problems
  • Numbness or tingling in the extremities


Your doctor will ask about symptoms and medical history, and perform a physical exam. He or she will also perform and MRI and/or CT scan to view the inside of the brain.

Cerebrospinal fluid (CSF) is a vital fluid that surrounds the brain and spine. Special studies to evaluate the flow of CSF may be performed.


Talk with your doctor about the best treatment plan. Treatment options include the following:


Surgery is usually required to correct any obstruction in the brain.

Treatment of Symptoms

Depending on the symptoms associated with Arnold-Chiari syndrome, other treatments may be beneficial. For instance, physical or occupational therapy can help improve muscular coordination and trembling. In addition, braces or a wheelchair may be needed. Speech therapy may also be beneficial.


There is no known way to prevent Arnold-Chiari syndrome. Parents of a child with this condition may benefit from genetic counseling.