Chiari Malformation

What is Chiari Malformation?

Chiari malformation also known as Arnold-Chiari malformaiton—happens at birth and is a condition where brain tissue extends into the spinal canal. This congenital malformation can affect the upper spinal cord, brain stem, cerebellum, and other surrounding structures. There are four types of Chiari malformations.

Type 1

Occurs while the brain and skull are still growing and is often seen in children. The lower part of the cerebellum extended into the foramen magnum, an opening at the skull’s base. Because type 1 develops as the child grows, it may not be apparent until late childhood, adolescence, or even adulthood.

Type 2

Is the most common type of congenital Chiari malformation. Type 2 is similar to 1 but has more serious malformations, since the brain stem and the cerebellum both go through the opening at the skull’s base. It is also associated with a form of spina bifida called meningomyelocele. Spina bifida causes the spinal cord and its protective coverings to develop incorrectly. This defect also cause a buildup of spinal fluid in the spinal cord and brain; and, it can cause incorrect signal transmissions from the brain to the body.

Type 3

Rare, but it is the most serious kind of Chiari malformation. This type causes the cerebellum and brain stem to herniate, or protrude, through the foramen magnum and spinal cord. This protrusion can cause an encephalocele, which causes serious neurological defects.

Type 4

Is a rare and serious kind of malformation where the cerebellum is underdeveloped or incomplete. Some portions of the spinal cord or the skull may be exposed as well.

There is no known cause of Chiari malformation, although researchers believe that genetics do play a role. Doctors believe that if the base of the skull is too little during development, then it can force the cerebellum downward.

What are the Symptoms of Chiari Malformation?

If a person has a mild type of Chiari malformation, then it is possible that they may never have symptoms or know that they have the condition. Headaches brought on after coughing or sneezing are quite common.

Other symptoms for type 1 include dizziness, neck pain, poor coordination, a build-up of fluid in brain cavities, tingling or numbness in extremities, hoarseness, vision issues, difficulty swalloing, sleep apnea, tinnitus, and scoliosis. Symptoms related to spina bifida are also common in more serious cases, as well as swallowing difficulties, arm weakness, uneven breathing, and nyastigmus.

Chiari Malformation Causes

The exact cause of Chiari malformation is unknown, though there are thought to be several potential causes. The most frequent cause of Chiari malformation is structural development problems in the brain and spinal cord area during the fetal stage. During development, Chiari malformation is caused if the part of the skull near the cerebellum does not develop properly and is too small. This blocks the flow of cerebrospinal fluid, which is the fluid protecting the brain. This puts pressure on the cerebellum, crowding the brain, and even displacing the lower part of the cerebellum into the upper part of the spinal column. It is possible that this is caused by genetic mutations or certain deficiencies in a maternal diet lacking nutrients and vitamins, as well as harmful substances ingested by the mother during development. This is known as congenital malformation.

On much rarer occasions, the disorder develops later in life when spinal trauma, disease, or infection causes excessive spinal fluid to drain into the lumbar or thoracic areas of the spine. This is called secondary malformation.

How is Chiari Malformation Treated?

Some people with Chiari malformation do not need to treatment if their symptoms aren’t severe. However, regular monitoring and analgesics may be used for less-severe cases. For more serious cases, a person may need to visit a neurologist or neurosurgeon for further treatment.

Surgeries that can help Chiari malformation are decompression surgery and laminectomies. Decompression surgery is a general term for many procedures that can relieve pressure on nerves and the spinal cord. A laminectomy is a procedure where one or more vertebrae is removed so that the spinal cord has more room and isn’t compressed.

Chiari Malformation Prevention

There are several known risk factors for congenital Chiari malformation that can be avoided. All of them involve problems that arise during fetal development. Common risk factors include a fetus being exposed to hazardous chemicals, alcohol, cigarette smoking, or illegal drug use by the mother, as well as lack of proper nutrients and vitamins in the diet of the mother. Serious infections or high fever during pregnancy can also cause fetal defects including Chiari malformation.

There is also a thought to be a genetic risk factor for Chiari malformation, though more research is being done to confirm this theory. It is thought that a genetic mutation may contribute and it may be hereditary.

Secondary Chiari malformation is caused by a wide range of other health issues that have their own sets of risk factors and is much rarer. Proper treatment of any health issues related to the spine is essential.

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Last Reviewed:
September 18, 2016
Last Updated:
December 01, 2017