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A Chiari malformation occurs when parts of the brain protrude through an opening in the base of the skull (foramen magnum) that normally only contains the spinal cord. In most kinds of Chiari malformation, the cerebellum (controls motion and balance) pushes through the opening in the skull that connects to the spinal canal. The brain stem also can be affected. These structural abnormalities put pressure on the cerebellum and brain stem, and this can block the normal flow of cerebral spinal fluid, which cushions the brain and spinal cord.
The exact cause of Chiari malformations is unknown. Theories suggest that exposure to toxins (such as hazardous substances, drugs or alcohol) or poor nutrition during fetal development may play a role.
Chiari malformations are present in approximately 1 in 1,000 people. The condition is classified by the severity of the disorder and the parts of the brain that protrude into the spinal canal. There are four types of Chiari malformation:
Many adults and children with Chiari malformations have no symptoms at all. Symptoms can vary by age group and be present alone or in combination.
Infants with any form of Chiari malformation may show these symptoms:
Symptoms of type I Chiari malformation include:
Symptoms of type II Chiari malformation include:
Type III and type IV Chiari malformation is rare, and children who are born with these types often do not survive. Symptoms of type III and type IV Chiari malformation include:
Chiari malformations may be associated with syringomyelia and hydromyelia. These disorders involve a buildup of cerebrospinal fluid that forms a cyst or cavity in the spinal cord. As the cyst (syrinx) grows, it can cause additional symptoms, including:
If your child shows signs of a Chiari malformation, a neurosurgeon will evaluate him or her to make an accurate diagnosis.
Specialists with Riley at IU Health perform the following exams and tests to diagnose Chiari malformations:
If diagnostic tests show that a Chiari malformation is present, a neurosurgeon will discuss with you the best treatment options for your child.
If no symptoms are present with a Chiari malformation, no treatment is needed. Your child’s neurosurgeon will simply monitor your child over time.
Treatment options include:
Your child’s neurosurgeon will discuss the benefits of surgery with you. While many patients see a reduction in symptoms, it is possible that surgery may not bring relief for every patient.
View these links to discover support groups and more resources for Chiari malformations.
Riley at IU Health offers a broad range of supportive services to make life better for families who choose us for their children's care.
This national group provides patient information about Chiari malformation.
The National Institutes of Health provide more information about the symptoms, treatment and research related to Chiari malformation.
The neurosurgery team at Riley at IU Health participates in research to find the best treatments for Chiari malformations and syringomyelia. We take part in the Park-Reeves Syringomyelia Research Consortium, a multicenter research effort that focuses on treatments for type I Chiari malformations.
Our neurosurgeons also actively work on the National Spina Bifida Patient Registry,
which is managed by the Centers for Disease Control and Prevention. This multicenter study evaluates the decision-making process and management of patients with myelomeningocele.
In addition to our primary hospital location at the Academic Health Center in Indianapolis, IN, we have convenient locations to better serve our communities throughout the state.