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​Chiari Malformation Causes, Symptoms and Treatments

Chiari malformation is a disease where the lower part of your brain extends down into the spinal canal. Common symptoms include headaches, balance problems, and sleep issues.

If you have a Chiari malformation, you may have questions about how to treat it.

Our experts at the UPMC Neurological Institute offer the most advanced treatments to help bring your symptoms under control.

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What Is a Chiari Malformation?

The cerebellum is the lower part of your brain. It normally rests just above the large opening in the base of your skull, called the foramen magnum.

In people with Chiari malformation, the lower part of the cerebellum (the tonsils) herniate below the foramen magnum.

As a result, the tonsils block the normal flow of the cerebrospinal fluid (CSF) in the brain. The abnormally located tonsils also put pressure on the spinal cord.

Most cases of Chiari malformation are congenital, meaning a person is born with it. The most common cause is a malformed or overly small posterior aspect of the skull.

With high-resolution imaging, doctors diagnose Chiari malformation in 1 out of every 100 people in the U.S. But only a fraction of them have symptoms. Doctors refer to this as Chiari syndrome.

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What Are the Types of Chiari Malformation?

There are a few types of Chiari malformations.

Chiari malformation type 1

In type 1, part of your cerebellum drops through the normal foramen magnum opening.

The cerebellum is the part of the brain that controls:

  • Balance.
  • Coordination.
  • Vision, including eye movements.
  • Motor learning.

Type 1 is the most common — and mildest — kind of Chiari malformation. This type may form while the skull and brain are growing. Symptoms may not occur until the teen or adult years.

Doctors often find type 1 during exams for other health issues. Many people with type 1 don't have any symptoms.

Chiari malformation type 2

Type 2 occurs in babies who are still growing inside their mother's wombs. In this type, both the cerebellum and the brain stem push through the normal opening to the spinal canal.

The brain stem, which is crucial for life, controls many body processes, such as:

  • Breathing.
  • Blood pressure.
  • Heart rate.
  • Sleep.
  • State of consciousness.

Type 2 occurs with a type of spina bifida called myelomeningocele. When this happens, the spine doesn't close in the proper way before birth.

Doctors diagnose this form of Chiari malformation when the mother is pregnant or shortly after birth.

Chiari malformation type 3

In type 3, the most severe form, the skull contains an abnormal opening. Part of the cerebellum and/or brain stem pass through this opening.

This form of Chiari malformation causes serious and even life-threatening issues.

Chiari malformation type 3 is very rare. As with type 2, parents tend to receive their child's type 3 diagnosis before birth.

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What Are the Risk Factors for Chiari Type 1?

Doctors can't yet predict who might be born with or get a Chiari malformation.

These malformations might run in families, but this research is still in its early stages.

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What Are the Symptoms of Chiari Malformation Type 1?

Many people with a Chiari malformation type 1 seen on imaging never get symptoms. When symptoms start in a person who has type 1, they can range from mild to severe.

Headaches are the most common symptom of type 1. They're often in the back of the head.

Headaches typically occur after:

  • Changing positions.
  • Coughing.
  • Laughing.
  • Lifting heavy objects.
  • Sneezing.
  • Straining.

Other symptoms include:

  • Blurry or double vision.
  • Feeling dizzy.
  • Memory problems.
  • Numbness or tingling in the hands or feet.
  • Sleep apnea.
  • Tinnitus or ringing in the ears.
  • Trouble swallowing.

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How Do Doctors Diagnose Chiari Malformation Type 1?

Your doctor will get your history and perform a complete physical exam, which may suggest a Chiari malformation type 1.

Next, your doctor will order imaging to get a detailed look at your brain and spinal cord.

UPMC experts often order 1 or more of these tests:

  • CT scan. These scans can detect bone problems in the skull and spine.
  • MRI. Besides giving a detailed view of bones, MRIs also show soft tissues. This test measures how far your cerebellum extends into the spinal canal.
  • CINE MRI. A special MRI that lets your doctor see how your CSF flows between your brain and spine.

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What Are the Treatment Options for Chiari Malformation Type 1?

Once your doctor confirms a Chiari malformation type 1, the key next step is to learn if it causes symptoms.

Some people with type 1 don't have any symptoms (Chiari syndrome). In that case, your doctor will want to observe you over time.

People with Chiari type 1 by imaging who have symptoms may need surgery. It's the only treatment that can improve the symptoms.

The most common surgery for Chiari malformation type 1 in adults is posterior fossa decompression.

In this surgery, neurosurgeons:

  • Remove a small section of bone from the back of the skull.
  • Open the tough sac that covers and protects the brain (the dura).
  • Place a permanent, waterproof patch to provide extra room. The extra room relieves pressure on the brain and lets the CSF flow freely again.

Most people stay in the hospital one to two days.

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Chiari Type 1 Surgery Complications

Because UPMC neurosurgeons care for many people with Chiari malformations, they've refined their techniques.

But complications may still arise, such as:

  • CSF leaks.
  • Infections.
  • Partial paralysis.
  • Swallowing problems.
  • Stroke.
  • Spine instability.

Surgery may also fail to relieve your symptoms.

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Why Choose the UPMC Neurological Institute for Care

UPMC has the largest Department of Neurosurgery in the U.S. People come from around the world to see our experts for care.

Each neurosurgeon is highly specialized, and is an expert in a small number of highly complex techniques.

They care for many people with the same health issue. In general, the more often a surgeon does a certain surgery, the better their results and safety record.

Plus, UPMC provides complete care to people with complex health issues.

Neurosurgeons, neurologists, ENT surgeons and specialists, and other providers work as a team to combine care throughout your stay.

Meet MaryMartha

MaryMartha – Chiari Malformation patient story 

An avid dancer and singer, MaryMartha faced a lifetime of symptoms caused by Chiari malformation. She found hope – and relief – at UPMC.

Read more »