What is Arnold-Chiari Malformation?

Tricia Christensen
Tricia Christensen

Certain types of defects in the brain’s bottom or cerebellum and the base of the skull can create an usual condition where brainstem and cerebellum move downward, inhibiting movement of spinal fluid and resulting in a wide number of symptoms, depending on severity. This is called a chiari malformation, and there are four types that may occur, including a Type I that may be relatively mild and which may not ever be diagnosed. Type II is known specifically as an Arnold-Chiari malformation, and it is a serious illness that can require multiple types of treatment.

A human brain. Arnold-Chiari malcormation affect the cerebellum, in light purple, and the brain stem, in darker purple at the bottom.
A human brain. Arnold-Chiari malcormation affect the cerebellum, in light purple, and the brain stem, in darker purple at the bottom.

In Arnold-Chiari malformation, which is often diagnosed at or before birth, part of the brain has been pushed into the spinal canal. Alone, this can create problems like trouble with balance, headaches, delay in coordination, feeding difficulties, breathing difficulties, and others. This is complicated by the fact that the brain malformations are present with an open spine, or spina bifida. The symptoms of this condition combine with those of Arnold-Chiari malformation, and children born with this illness may have poor control of bladder, and fractional or total paralysis in the lower part of the body.

The specific type of spina bifida associated with Arnold-Chiari malformation is myelomeningocele. This is often classed as a severe type and typically requires early surgical intervention. One of the big issues is that fluid on the brain can develop quickly. Early surgery may be needed to create a shunt in the brain that helps to process this extra fluid and drain it, and additional surgery could be necessary to close the spine. The shunt and spinal repair don’t necessarily address all issues associated with the condition

Growing pressure on the brain, even with a shunt for fluid drainage, may require more extensive brain surgery. Neurosurgeons may decide to treat Arnold-Chiari malformation or other types of Chiari malformations with surgery that helps give the brain more room. Each surgery could be individualized to patient needs but most may excise some bone in the skull, usually in the back, to create a less pressured space for the cerebellum.

Though surgery may improve certain symptoms associated with Arnold-Chiari malformation, it doesn’t fix all issues. Damage caused by spinal defect is typically permanent, even if that defect can be repaired. Early treatment, though, can make a huge difference.

For those interested in preventing Chiari Type II and spina bifida, the most important step is to begin taking folic acid supplements several months prior to pregnancy. This supplement has been shown to dramatically reduce incidence of spinal or neural tube defects. Though there is some suggestion of weak genetic link with both these disorders, folic acid use may help to negate or lower this risk.

Tricia Christensen
Tricia Christensen

Tricia has a Literature degree from Sonoma State University and has been a frequent wiseGEEK contributor for many years. She is especially passionate about reading and writing, although her other interests include medicine, art, film, history, politics, ethics, and religion. Tricia lives in Northern California and is currently working on her first novel.

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