Condition Chiari & CSF Disorders

Chiari Malformation

A Chiari malformation occurs when the lower part of the brain extends below the base of the skull into the upper spinal canal. While some people never develop symptoms, others experience headaches, neck pain, balance problems, numbness, or weakness due to pressure on the brain and disruption of cerebrospinal fluid (CSF) flow. Specialized evaluation helps determine whether observation or treatment is the best approach.

Medically reviewed by Kate T. Carroll, MD Last reviewed January 2, 2026 6 min read

Quick Answer

A Chiari malformation is a condition in which the lower part of the cerebellum extends below the base of the skull into the spinal canal. This can crowd the area where the brain meets the spine, disrupting the normal flow of cerebrospinal fluid (CSF) and placing pressure on nearby nerves. Some people have no symptoms and only require monitoring, while others develop headaches, neck pain, balance problems, weakness, or other neurological symptoms. Treatment is based on your symptoms, neurological examination, and MRI findings.

Key Takeaways

A Chiari malformation occurs when part of the cerebellum extends into the upper spinal canal.
Many people have no symptoms and may only require observation.
Common symptoms include headaches, neck pain, balance problems, numbness, weakness, and difficulty swallowing.
Chiari malformation may be associated with syringomyelia, hydrocephalus, or scoliosis.
Treatment ranges from careful monitoring to posterior fossa decompression surgery, depending on symptoms and imaging findings.

At a Glance

Type	Chiari I malformation (the most common form)
Who it affects	Children and adults; many people are diagnosed after developing symptoms or after an MRI performed for another reason.
Common symptoms	Headaches, neck pain, balance problems, dizziness, numbness, weakness, and difficulty swallowing.
Associated conditions	Syringomyelia, hydrocephalus, scoliosis, and tethered cord syndrome.
Diagnosis	Neurological examination and MRI, with additional brain or spine imaging when appropriate.
Treatment	Observation or posterior fossa decompression surgery, depending on symptoms and imaging findings.
Long-term outlook	Many people experience excellent long-term outcomes with appropriate monitoring or treatment.

Understanding Chiari Malformation

What Is a Chiari Malformation?

A Chiari malformation occurs when the lower part of the brain, called the cerebellar tonsils, extends below the opening at the base of the skull (the foramen magnum) into the upper spinal canal. This crowds the area where the brain meets the spinal cord and can interfere with the normal flow of cerebrospinal fluid (CSF).

Some people with a Chiari malformation never develop symptoms and discover the condition incidentally during an MRI performed for another reason. Others develop symptoms because of pressure on the brainstem, upper spinal cord, or disruption of normal CSF flow.

Conditions Associated with Chiari Malformation

Some people with Chiari malformation develop additional conditions that may require evaluation or treatment.

Syringomyelia

A fluid-filled cavity that develops within the spinal cord.

Hydrocephalus

A buildup of cerebrospinal fluid within the brain.

Scoliosis

Abnormal curvature of the spine, particularly important to evaluate in children.

Tethered Cord Syndrome

A condition in which the spinal cord is abnormally attached within the spinal canal.

Identifying these associated conditions helps guide treatment decisions and long-term follow-up.

Why Evaluation Is Important

Not every Chiari malformation requires treatment. The decision to observe or recommend surgery depends on your symptoms, neurological examination, MRI findings, and whether the Chiari malformation is affecting the brain, spinal cord, or normal flow of cerebrospinal fluid.

A comprehensive neurosurgical evaluation helps determine whether monitoring or treatment is the most appropriate approach.

Signs & Symptoms

Many people with Chiari malformation never develop symptoms and only learn they have the condition after an MRI performed for another reason. When symptoms do occur, they vary depending on the degree of crowding at the base of the skull, disruption of cerebrospinal fluid flow, and whether associated conditions such as syringomyelia are present.

COMMON SIGNS & SYMPTOMS

Adults

Headaches, especially after coughing, sneezing, or straining
Neck pain
Dizziness or balance problems
Numbness or tingling in the arms or hands
Weakness in the arms or legs
Difficulty swallowing
Hoarseness or changes in voice
Ringing in the ears
Poor coordination or clumsiness

COMMON SIGNS & SYMPTOMS

Children

Children may experience many of the same symptoms as adults but may have difficulty describing them. Signs may include:

Headaches or neck pain
Irritability
Difficulty swallowing or feeding
Balance or walking problems
Weakness
Scoliosis
Developmental concerns

When Syringomyelia Is Present

A syrinx within the spinal cord can cause additional symptoms such as progressive weakness, loss of sensation, chronic pain, muscle stiffness, or difficulty with fine motor skills.

When to Seek Medical Evaluation

If you or your child has symptoms that are persistent, worsening, or affecting daily activities, neurological evaluation may be appropriate—particularly with progressive weakness or numbness, changes in balance or walking, difficulty swallowing, or worsening headaches triggered by coughing or straining. For someone already diagnosed with Chiari malformation, new or progressive neurological symptoms should prompt reevaluation.

Diagnosis

How Is Chiari Malformation Diagnosed?

Diagnosing Chiari malformation begins with a thorough medical history and neurological examination. Your neurosurgeon will evaluate your symptoms, neurological function, and overall health before recommending imaging studies to confirm the diagnosis and determine whether the Chiari malformation is responsible for your symptoms.

Because many people have a Chiari malformation without symptoms, diagnosis is based on both imaging findings and your clinical presentation—not MRI findings alone.

Neurological Evaluation

Your neurosurgeon reviews symptoms and examines strength, sensation, balance, coordination, reflexes, gait, cranial nerve function, and swallowing or speech when appropriate.

MRI of the Brain & Spine

MRI is the primary imaging study used to evaluate the position of the cerebellar tonsils and identify associated conditions such as syringomyelia or hydrocephalus. Imaging of the cervical spine may also be recommended.

Additional Testing When Needed

Depending on symptoms and imaging findings, additional studies may include cine MRI to evaluate cerebrospinal fluid flow, MRI of the entire spine, swallowing evaluation, or sleep evaluation.

Treatment

Treatment for Chiari malformation is individualized. Not everyone with Chiari requires surgery. Your neurosurgeon considers your symptoms, neurological examination, MRI findings, associated conditions, and whether normal cerebrospinal fluid flow is affected when determining the best approach.

Conservative Care

Observation & Monitoring

For people with no symptoms or only mild, stable symptoms, periodic neurological follow-up and MRI may be appropriate. Monitoring helps identify changes in symptoms, cerebrospinal fluid flow, or associated conditions over time.

Surgical Treatment

Posterior Fossa Decompression

For significant symptoms or neurological compression, posterior fossa decompression creates more space at the base of the skull and may improve the flow of cerebrospinal fluid around the brain and spinal cord.

Related Conditions

Treating Associated Conditions

Treatment planning may also need to address associated conditions such as syringomyelia, hydrocephalus, tethered cord syndrome, or scoliosis when they contribute to symptoms or affect the overall treatment approach.

Long-Term Outlook

Many people with Chiari malformation lead active, healthy lives. Whether treatment involves observation or surgery, regular follow-up helps monitor symptoms and identify changes that may require additional evaluation.

For patients who require surgery, posterior fossa decompression can relieve pressure and improve cerebrospinal fluid flow. Outcomes vary depending on symptoms, associated conditions such as syringomyelia, and the extent of neurological involvement.

Specialized Chiari Care for Children and Adults

Atlantic Brain and Spine provides specialized evaluation and surgical care for Chiari malformation in children and adults. Our team brings together expertise in pediatric neurosurgery, complex cranial surgery, and spine care to address Chiari and associated conditions such as syringomyelia, hydrocephalus, scoliosis, and tethered cord syndrome.

The Diagnosis-to-Treatment Pathway

1. Confirm the clinical picture

Symptoms, neurological examination findings, and MRI results are considered together to determine whether Chiari malformation is contributing to the patient’s symptoms.

2. Assess severity and associated conditions

Cerebrospinal fluid flow and associated conditions such as syringomyelia, hydrocephalus, scoliosis, or tethered cord syndrome are evaluated because they may affect treatment decisions.

3. Determine whether treatment is needed

Not every Chiari malformation requires surgery; the goal is to determine whether observation or surgical treatment is the most appropriate approach.

4. Observation when appropriate

Patients with no symptoms or mild, stable symptoms may be followed with neurological examinations and periodic imaging.

5. Surgery when indicated

Posterior fossa decompression may be recommended for significant or progressive symptoms, neurological deficits, impaired CSF flow, or associated conditions that warrant treatment.

6. Long-term follow-up

Symptoms, neurological function, imaging findings, and associated conditions are monitored over time.

Frequently Asked Questions

A Chiari malformation is a condition in which the lower part of the brain, called the cerebellar tonsils, extends below the base of the skull into the upper spinal canal. This can disrupt the normal flow of cerebrospinal fluid (CSF) and, in some people, place pressure on the brainstem or spinal cord.

Some people never develop symptoms, while others experience headaches, neck pain, dizziness, balance problems, numbness, weakness, difficulty swallowing, or changes in coordination. Symptoms vary depending on the degree of compression and whether associated conditions are present.

No. Many Chiari malformations are discovered incidentally and never require surgery. Observation may be appropriate when symptoms are absent or mild and stable. Surgery is generally considered when symptoms are significant or progressive, neurological problems develop, cerebrospinal fluid flow is disrupted, or associated conditions such as syringomyelia are present.

Posterior fossa decompression is the most common surgical procedure used to treat symptomatic Chiari malformation. The surgery creates additional space at the base of the skull, relieving pressure on the brain and restoring the normal flow of cerebrospinal fluid.

Syringomyelia is a fluid-filled cavity (syrinx) that develops within the spinal cord. It is commonly associated with Chiari malformation and can cause pain, weakness, numbness, or loss of coordination if left untreated.

Yes. Chiari malformation can affect both children and adults. Some children are diagnosed after developing headaches, neck pain, scoliosis, or balance problems, while others are diagnosed after imaging performed for another reason.

Diagnosis typically involves a neurological examination and an MRI of the brain and cervical spine. Additional imaging or specialized testing may be recommended depending on your symptoms and whether associated conditions are suspected.

Many people with Chiari malformation live active, healthy lives. Whether treatment involves observation or surgery, regular follow-up helps monitor symptoms and identify changes that may require additional evaluation.