Chiari Malformation Guide

Chiari I occurs when a portion of the brain called the cerebellar tonsils (the lower part of the cerebellum) extends out of the skull and into the upper part of the spinal canal. This can disrupt the flow of cerebrospinal fluid—somewhat like a rock in the middle of a stream. Chiari I can cause symptoms in infancy, but symptoms sometimes do not occur until late childhood or early adulthood, if at all. The malformation is often diagnosed when a person undergoes imaging tests for unrelated reasons.

Chiari II, also often called Arnold-Chiari malformation, occurs when the cerebellar tonsils and the brain stem push down through the base of the skull into the upper spinal canal. Chiari II is present at birth, and typically is seen in infants with myelomeningocele (a form of spina bifida) and/or hydrocephalus (a buildup of cerebrospinal fluid in the brain). It is the most common type of Chiari malformation.

Chiari III and IV are very rare and may be life-threatening. Please talk to your child’s physician for more information about these diagnoses.

Symptoms may vary for each child, as there are a variety of problems that can occur with Chiari malformations.

Chiari I 
The main symptom with Chiari I is headache in the back of the brain, which can be severe. Other problems can include:

• Dizziness and balance problems
• Double or blurred vision
• Numbness
• Spontaneous gagging and vomiting
• Sensitivity to bright lights

In rare cases, a child will experience sleep apnea, a condition in which breathing pauses during sleep.

Diagnosing Chiari I in an infant is challenging, since symptoms are not always obvious and the child is not able to communicate exactly what is wrong. Common signs can include irritability, head banging and nighttime awakening.

About 50 percent of patients with a Chiari I malformation also develop a syrinx (fluid-filled cavity in the spinal cord). A syrinx, also known as syringomyelia or hydromyelia, is caused by an obstruction in the normal flow of cerebrospinal fluid. A syrinx expands over time, and can injure nerve fibers in the spinal cord. It eventually can cause symptoms such as:

• Muscle weakness in the extremities
• Muscle stiffness
• Reduced ability to feel pain or temperature
• Chronic pain
• Loss of bladder and bowel control
• Numbness and tingling
• Clumsiness

Chiari II 
Chiari II is typically seen in infants with myelomeningocele, a form of spina bifida, with accompanying signs and symptoms of Chiari malformation, which can include swallowing problems and slow or noisy breathing. The condition can lead to trouble while feeding, as well as gagging, drooling and vomiting.

Children with a Chiari malformation sometimes have other associated conditions. For this reason, it is important that they receive care from a multidisciplinary team that includes physicians who specialize in pediatric neurosurgery, neurology, disorders of the ear, nose and throat, and other areas of medicine.

Conditions associated with Chiari I 
Patients with Chiari I may develop a syrinx, scoliosis, and/or have a tethered spinal cord.

• A syrinx is a fluid-filled cavity in the spinal cord. It can lead to a number of neurological problems. These include muscle stiffness, weakness and pain. Surgeons typically do not operate to correct the syrinx. But surgery to correct the Chiari malformation may relieve these symptoms.
• A syrinx can cause scoliosis an abnormal curvature of the spine. For some children, treating the Chiari malformation can alter the progression of scoliosis. In other cases, children may need additional surgery to treat the scoliosis itself.
• In rare cases, a child with a Chiari malformation may have a tethered spinal cord. This means that their spinal cord is attached to tissues around the spine in an abnormal way. A child may need surgery to correct the tethered cord, in addition to treatment for the Chiari malformation.

Children with Ehlers-Danlos syndrome (EDS) may be at increased risk for Chiari I malformation. EDS is a connective tissue disorder that causes hypermobility and unstable joints.

Conditions associated with Chiari II 
Two serious conditions associated with Chiari II are myelomeningocele and hydrocephalus. A multidisciplinary team can help diagnose and treat these conditions.

• Myelomeningocele is a severe form of spina bifida, in which a portion of the spinal cord and surrounding nerves stick out from an opening in the spine. Children with myelomeningocele sometimes have other medical problems, including hydrocephalus and heart defects.  
• Hydrocephalus is a buildup of cerebrospinal fluid in the brain and spinal cord.

In addition, some children with Chiari I or II have some form of sleep apnea, in which they stop breathing temporarily during sleep. Treating the Chiari malformation may eliminate or lessen the sleep apnea.

A magnetic resonance imaging (MRI) test is the best way to detect a Chiari malformation. An MRI can create three-dimensional images of the brain and upper spinal cord from many angles, which helps to make an accurate diagnosis. It can also help physicians see whether the child has a syrinx within the spinal cord or a tethered spinal cord. Follow-up MRIs can help the medical team see whether the Chiari malformation changes or worsens over time.

Once the medical team establishes a diagnosis of Chiari malformation, other tests can be used to help evaluate the child’s condition. These include:

• Computed tomography (CT) scan, a test that can show blockage in the spinal canal.
• Ultrasound scan, a test to evaluate motion of the cerebellar tonsils during surgery
• Electrical tests called evoked potentials. These can determine whether the brainstem is functioning properly, and give information about peripheral nerves, the spinal cord and brain function.
• A swallowing test to show how well the child is able to drink liquids or swallow thickened food. This test is helpful for children who experience gagging or excessive drooling.
• A sleep study to look at a child’s breathing pattern and determine whether enough oxygen is getting to the brain during sleep. This test is helpful for children who have a history of noisy sleeping or snoring.

Treatment for Chiari I and II varies depending on the exact type of malformation, the progression of the structural defect and the child’s symptoms.

Some children never require treatment for a Chiari malformation. Others are able to enjoy a good quality of life with the help of non-surgical therapies, such as pain-relief medicine or physical therapy.

If your child has a syrinx in the spinal cord, the team will recommend decompression surgery to relieve pressure on the brain and spinal cord. A shunt may be needed to establish a normal flow of brain and spinal fluid around and behind the cerebellum.

When surgery is needed, results are often very positive. Many children are symptom free or have significantly fewer symptoms. Long-term monitoring includes performing MRIs at regular intervals to evaluate the results of the decompression, the response of any associated syrinx, and any scar tissue development.

Read more about treatment for Chiari malformation.