Chiari Malformations
What are Chiari malformations?
Chiari malformations are defects in the part of the brain that controls balance. In a Chiari malformation, the lower part of the skull is smaller than normal, which causes the cerebellum and brainstem to be pushed downward. The defect puts pressure on the cerebellum and brainstem and block the flow of cerebrospinal fluid, the fluid that surrounds and cushions the brain and spinal cord. The majority of Chiari malformations fall into one of three categories:
Type I: This is the most common type and may not cause symptoms but may be found during examinations for other conditions.
Type II: This also is called an Arnold-Chiari malformation or classic Chiari malformation. It often is accompanied by myelomeningocele (a form of spina bifida where a portion of the spinal cord protruding from an opening in the back, causing partial or complete paralysis.)
Type III: In Type III, the most serious type, the cerebellum and brainstem protrude outside of the brain and into the spinal cord. Sometimes, part of the brain’s fourth ventricle also protrudes into the spinal cord. In rare instances, the protrusion causes an encephalocele, a pouch-like structure containing brain matter that is visible in the back of the head or neck. Children with Type III malformations typically have severe neurological defecits.
Chiari malformations occur more often in girls than boys. Type II malformations are more common in certain ethnic groups, including people of Celtic descent.
In the past, it was estimated that the condition occurs in about one in every 1,000 births. However, the increased use of diagnostic imaging has shown that CM may be much more common. Complicating this estimation is the fact that some children who are born with the condition may not show symptoms until adolescence or adulthood, if at all. CMs occur more often in women than in men and Type II malformations are more prevalent in certain groups, including people of Celtic descent.
What are the symptoms?
Chiari malformations happen more often in children with hydrocephalus, spina bifida, syringomyelia, and/or tethered cord syndrome. Not all children with Chiari malformations have symptoms, or symptoms may not appear until a child enters adolescence or even adulthood. Symptoms often are different in older children than they are in babies.
In older children, there may be:
- Balance, dizziness, and/or coordination problems
- Neck pain
- Muscle weakness, numbness or other abnormal feelings in the arms and legs
- Vision problems
- Problems with swallowing
- Vomiting
- Ringing, buzzing, or loss of hearing in the ears
- Insomnia
- Depression
- Headache that gets worse when your child is coughing or straining
Infants may have the following symptoms:
- Difficulty swallowing
- Irritability when being fed
- Excessive drooling
- A weak cry
- Gagging or vomiting
- Arm weakness
- A stiff neck
- Breathing problems
- Developmental delays
- Inability to gain weight
How are they treated?
Medication and surgery can help the symptoms of Chiari malformations. Surgery involves making an incision at the back of the head in order to remove a small portion of bone at the bottom of the skull. A related procedure, called a spinal aminectomy, involves removal of some of the bone of the spinal cord. Surgery can prevent further damage to the central nervous system and can reduce symptoms. More than one surgery may be necessary to treat the problem.
About Surgery for Chiari malformations at Children’s
The neurosurgery team at Children’s provides next-generation care to neonatal infants, newborns, children, and adolescents from throughout the Upper Midwest. The team provides some of the most cutting-edge treatments available, including newborn surgery, surgery utilizing intra-operative MRI, and grid placement surgery for epilepsy. Neurosurgery is performed at Children’s - Minneapolis and Children’s - St. Paul.
If you are a family member looking for a Children’s specialist in neurosurgery, visit Find a Doctor.
If you are a health professional looking for a consultation or referral information, please call Children's Physician Access at 1-866-755-2121 (toll-free).
Return to Children’s neurosurgery home page.
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