Chiari malformation

At Boston Children’s Hospital, we have already helped many infants, children and adolescents who have been diagnosed with a Chiari malformation, an abnormality in the meeting of the brain and the spinal cord at the base of the child’s skull.

There are four types of Chiari malformation. Type I is by far the most common form of the condition in children, while type II is typically only seen in children with spina bifida. The other types of Chiari malformation are extremely rare.

For the purposes of this webpage, the information you will read below focuses only on type I and type II Chiari malformation.

Here are some of the basics about Chiari malformation:

Type I:

• Type I Chiari malformation occurs in around 3 percent of the general population. However, since individuals with this condition often don’t show symptoms and go undiagnosed, it’s difficult to say exactly how many people actually have it.

• Most children with type I Chiari malformations have no signs or symptoms and are only diagnosed when they get a magnetic resonance imaging (MRI) scan for another problem.

• When symptoms occur, they typically present in late childhood or early adulthood and usually include neck pain. Other symptoms may include balance problems, sleep apnea (a common disorder that causes pauses in breathing during sleep) and swallowing difficulties.

• The Chiari malformation can also cause fluid to accumulate in the spinal cord – a condition called syringomyelia – which can cause scoliosis in children. Syringomyelia can also make it harder for the brain to process and organize sensory information that comes from the surrounding environment.

• If the Chiari malformation is not causing problems for the child, no treatment is needed. When symptoms do occur, treatment generally involves surgery to relieve pressure on the cerebellum, brain stem and spinal cord.

Type II:

• Type II Chiari malformation occurs when the tissue from the cerebellum, along with the brain stem itself, protrude downward through the base of the skull into the upper spinal canal.

• Type II Chiari malformation almost always affects children who have spina bifida. It is present at birth (congenital).

• Most children with this form of the condition require treatment for buildup of fluid in the brain (hydrocephalus).

How Boston Children’s approaches Chiari malformation

Since a child with a type I Chiari malformation may not have symptoms, the safest approach is to leave it untreated and perform a follow-up evaluation by MRI and examination if necessary. However, for symptomatic patients, or those who have developed an accumulation of fluid in the spinal cord, we typically recommend surgical treatment.

Chiari malformation: Reviewed by Benjamin C. Warf, MD
© Children’s Hospital Boston; posted in 2012