Chiari Malformation

1 What is Chiari Malformation?

Chiari malformations are structural defects characterized by protrusion of brain tissue into your spinal canal. When your skull is abnormally small, the brain is forced to move downward.

Initially Chiari malformations were rarely reported, probably due to limited high quality imaging tests but more cases are being diagnosed now owing to improved scanning technologies.

Of the three types, Chiari malformation type I begins while the skull and brain are growing. Consequently, signs and symptoms may not be apparent till late childhood or adulthood.

The most common type, Chiari malformation type II is an innate condition.

Chiari malformation III is the most serious of the three types and is associated with higher mortality rate.

The treatment options are determined by severity and type of the malformation, and include monitoring, medications and surgery.

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2 Symptoms

Many people with Chiari malformation may show no signs or symptoms and require no treatment. Their condition is accidently detected while testing for some other disorders. The signs and symptoms when present, vary according to the type of the malformation.

Chiari malformations are categorized into three types based on which part of the brain is affected.

The types are:

Type I

Lower part of the cerebellum, not brain stem, protrudes into an opening at the base of the skull which in general allows only spinal cord to pass through. The signs and symptoms appear during late childhood or adulthood. This type is less serious than Type III, but signs and symptoms can still be distressing. Type I symptoms are triggered by coughing, sneezing or straining.

  • Neck pain
  • Balance problems
  • Poor hand coordination (fine motor skills)
  • Numbness and tingling of the hands and feet
  • Dizziness
  • Difficulty swallowing, sometimes accompanied by gagging, choking and vomiting
  • Vision problems (blurred or double vision)
  • Speech problems, such as hoarseness

Less often, people with Chiari malformation may experience:

Type II

Ultrasound during pregnancy can reveal this type. However, some cases are diagnosed after birth or in early infancy. Unlike in type I, both cerebellum and brain stem are pushed into the spinal canal. Almost all the cases are characterized by signs and symptoms related to a serious form of spina bifida, myelomeningocele. Myelomeningocele is a condition in which the backbone and the spinal canal haven't closed properly before birth.

Symptoms may include:

  • Changes in breathing pattern
  • Swallowing problems, such as gagging
  • Quick downward eye movements
  • Weakness in arms

Type III

In this type, both cerebellum and brain stem herniate into the spinal canal and is the most serious of all three types. The diagnosis is commonly made at birth or by an ultrasound during pregnancy. A higher mortality rate and associated neurological complications are common.

When to see a doctor

If you or your child has any of the signs and symptoms that may be associated with Chiari malformation, see your doctor for an evaluation. Because many symptoms of Chiari malformation can also be associated with other disorders, a thorough medical evaluation is important.

3 Causes

The causes of Chiari malformations may vary depending on its types.

In Type I, the part of skull containing cerebellum is too small or is deformed that lower part of the cerebellum is pushed into your upper spinal canal.

In Type II, the cerebellum and brainstem are pushed into the upper spinal canal. This can obstruct normal flow of spinal fluid, a fluid that protects your brain and the spinal cord resulting into accumulation of the fluid in the brain or spinal cord.

Almost all cases are associated with a serious form of spina bifida called myelomeningocele.

In addition, the neurological signs or symptoms can also arise due to stress exerted by the cerebellum on the spinal cord or lower brainstem.

4 Making a Diagnosis

The diagnosis of Chiari malformation begins with review of your medical history and symptoms followed by physical examination.

Visit your doctor if you experience any signs or symptoms. Your doctor may refer you to a specialist in disorders of nervous system (neurologist).

How to prepare yourself for the visit

  • Getting prepared for the visit can optimize the therapy and help make the visit more fruitful.
  • List out all the symptoms.
  • Write down your key medical information.
  • Write down the names of all your medications, vitamins or supplements.
  • Make a list of the questions to ask your doctor.

Some typical questions can be:

  • What could be possible causes of my symptoms?
  • What are the tests I need?
  • Do I need treatment? If no, how will you monitor changes in my condition?
  • Do I need surgery? If yes, how will be my recovery?
  • What are the risks of surgery?
  • How will be my long-term prognosis following surgery?

What your doctor wants to know

A clear talk with your doctor can optimize the therapy and improve the outcomes. Prepare yourself to answer some essential questions from your doctor.

Your doctor might ask you typical questions like:

  • When did the symptoms start appearing?
  • Is your pain, in head and neck, worsened by sneezing, coughing or straining?
  • How severe is your head and neck pain?
  • Have you noticed any change in your coordination, including problems with balance or with hand coordination?
  • Do you feel numbness or tingling sensations in hand and feet?
  • Do you have any difficulty during swallowing?
  • Do you experience episodes of dizziness or faintness?
  • Do you have blurred vision or a ringing or buzzing in your ears?
  • Is your bladder function normal?
  • Do you experience episodes of breathlessness during sleep?
  • Do you have a family history of Chiari malformation?
  • Have you experienced any other problems like hearing impairment, fatigue, or changes in your bowel habits or appetite?

You may be recommended imaging tests like:

  • Magnetic resonance imaging (MRI): It is a safe and non-invasive imaging test that uses powerful radio waves and magnets to create cross sectional images of your brain and spinal cord. Any abnormality that contributes to the symptoms can be analyzed by using MRI. MRI forms the cornerstone of Chiari malformation diagnosis. Repeated MRI scan are done to monitor the progression of your disorder.
  • Computerized tomography (CT) scan: A CT scan uses numerous X-ray images to create a detailed view of your brain and spinal cord. Abnormalities like brain tumors or brain damage can show up during the scan.

5 Treatment

Severity of Chiari malformation determine which treatment option is suitable to you. If you are lucky to have no symptoms, no treatment may be recommended.

  • Pain medications: Pain relievers may be recommended to reduce pain like headache.
  • Reducing pressure by surgery: Surgery is a common treatment option that aims to reduce pressure on cerebellum and spinal cord, and bring spinal flow back to normal. The most common surgery is posterior fossa decompression in which a small section of bone in the back of your skull is removed to lift pressure from the cerebellum and spinal cord. Alternately, a part of your spinal cord may be surgically removed to relieve pressure on your spinal cord.
  • Surgical risks and follow-up

Like any other major surgery, the surgery for Chiari malformation is also associated with many risks that include possibility of infection, fluid in your brain, cerebrospinal fluid leakage or delayed wound healing.

Talk to your doctor about the risk and expected benefits of each surgery option. Remember that surgery may help alleviate symptoms in most people, but it is of no use if nerve injury in the spinal canal has already occurred.
Regular follow ups are required to monitor progress and flow of spinal fluid.

6 Risks and Complications

There are several risks and complications associated with Chiari malformation.


Chiari malformation may be inheritable but more studies are required to establish this.


  • Hydrocephalus: Hydrocephalus is fluid build-up within your brain.
  • Spina bifida: Chiari malformations is closely associated with a condition in which there is incomplete development of spinal cord or its covering, spina bifida. This may lead to paralysis. Type II is related to a serious form of spina bifida called myelomeningocele.
  • Syringomyelia: Chiari malformation may lead to a condition called syringomyelia in which cavities form within the spinal column.
  • Tethered cord syndrome: In this condition, there is limited movement of spinal cord within the spinal column as your spinal cord is attached to your spine. This can result in serious nerve and muscle damage in your lower body.