Chiari malformation is a structural defect involving the portion of the brain known as the cerebellum, which is responsible for balance and coordination. The condition occurs when part of the skill is too small or misshapen, which causes the brain to press down onto the spinal cord. It is estimated that one in 1,000 children are born with the defect. The number may even be higher since some individuals born with the condition never develop symptoms.

Types of Chiari Malformations

There are four types of Chiari malformations:
• Type I—This is the most common form of Chiari malformation. The lower portion of the cerebellum extends into the opening at the base of the skull known as the foramen magnum.
• Type II—In this kind of malformation, both the brain stem and the cerebellum extend in the foramen magnum. This malformation is almost always associated with spina bifida, which is a condition where the spinal cord and its protective covering do not develop properly.
• Type III—This type of malformation is the most serious and is rare. The cerebellum and brain stem herniate or protrude into the spinal cord. Individuals with this form of malformation typically experience severe neurological defects.
• Type IV—This is another rare form of the condition that occurs when the back of the brain does not develop completely.

Detailed physical exams, patient history, and MRIs are the most common tools used to diagnose Chiari malformations.

Causes of Chiari Malformation

The cause of Chiari malformation is not clear; however, it is believed there may be a genetic component since the condition can run in families. Other factors can affect fetal brain and head development and potentially cause the malformation, including:

A diet that is lacking in necessary vitamins and nutrients during pregnancy
Infections
Exposure to hazardous substances and chemicals
Drug and alcohol use during pregnancy

Symptoms of Chiari Malformation

The symptoms of Chiari malformation can vary depending on the severity of the defect. The most common symptoms include:

Headaches that are often worse when coughing, sneezing, or bending over
Pain or stiffness in the back of the head or neck
Difficulty feeding or swallowing
Decreased strength and sensation in the arms and legs
Developmental delays
Breathing problems, including sleep apnea
Weak cry or voice
Rapid back and forth eye movements

Treatment

If the malformation causes symptoms, treatment may involve medications to control pain and surgery to correct the defect, prevent damage to the central nervous system, and relieve pressure on the brain. Most patients undergoing surgery experience a significant reduction or elimination of their symptoms.