Chiari Malformation

Overview

Chiari malformation is a condition in which part of the brain, usually the lower part of the cerebellum, sits lower than normal and pushes down through the opening at the base of the skull into the spinal canal. This can crowd the area and interfere with the normal flow of cerebrospinal fluid, the liquid that cushions the brain and spinal cord.

Many people have a Chiari malformation without ever knowing it, and it is sometimes found by chance on a scan done for another reason. When it does cause problems, symptoms often relate to pressure at the junction of the brain and spine. Treatment ranges from monitoring to surgery, depending on severity.

Symptoms

Symptoms vary widely; some people have none. A classic feature is a headache at the back of the head that worsens with coughing, sneezing, or straining. Other symptoms include:

• Neck pain
• Dizziness, balance problems, or unsteadiness
• Numbness or tingling in the hands or arms
• Ringing in the ears or hearing changes
• Difficulty swallowing
• Vision changes
• Muscle weakness

In infants and young children, signs can include feeding difficulties, breathing problems, and developmental delays, which warrant prompt evaluation.

Causes

Most Chiari malformations are present from birth and result from the skull being slightly too small or misshapen at the back, leaving too little room for the brain. The exact reason this develops is not fully understood, though genetic factors may play a part.

• Type I: The most common form, often not causing symptoms until later childhood or adulthood.
• Type II: More involved and usually associated with spina bifida, present at birth.

Less commonly, a Chiari malformation can be acquired later in life, for example from a condition that drains too much spinal fluid.

Risk Factors

• Being born with a smaller or misshapen lower skull
• Spina bifida (associated with Type II)
• A family history of Chiari malformation
• Certain conditions affecting spinal fluid pressure

Diagnosis

Chiari malformation is usually identified with brain and spine imaging. Evaluation may include:

• MRI: The most useful test, showing how far the brain tissue extends and whether fluid flow is affected.
• CT scan: Sometimes used to look at the bones of the skull base.
• Specialized MRI of fluid flow: To assess how cerebrospinal fluid moves.

Because many malformations are found incidentally, doctors weigh the imaging against the person's actual symptoms before recommending treatment.

Treatment

Treatment depends on the type, the symptoms, and whether complications such as a fluid-filled spinal cord cavity are present.

• Monitoring: For people with no or mild symptoms, regular follow-up and imaging may be all that is needed.
• Medication: Pain relievers to manage headaches and neck pain.
• Surgery: The main treatment for significant or worsening symptoms. The most common operation removes a small piece of bone at the base of the skull to create more room and restore fluid flow.

Surgery often relieves symptoms and can halt further nerve damage, though results vary.

Prevention

Chiari malformation is usually present from birth and cannot be prevented. For the type linked to spina bifida, good prenatal care matters.

• Adequate folic acid before and during early pregnancy lowers the risk of spina bifida
• Regular prenatal care to detect and manage related conditions
• Prompt evaluation of new neurological symptoms so problems are caught early

When to See a Doctor

See a doctor if you have persistent headaches at the back of the head that worsen with coughing or straining, ongoing neck pain, dizziness, or numbness in the arms. These deserve evaluation, often with an MRI.

Seek urgent care for sudden severe symptoms such as difficulty breathing or swallowing, fainting, severe weakness, or, in a baby, choking, persistent breathing pauses, or feeding problems, as these can signal pressure on vital nerves.

Related Topics

Frequently Asked Questions

References

1. National Institute of Neurological Disorders and Stroke (NINDS). Chiari Malformation.
2. Mayo Clinic. Chiari malformation — Symptoms and causes.
3. MedlinePlus, U.S. National Library of Medicine. Chiari malformation.
4. American Association of Neurological Surgeons (AANS).