Chiari Malformation and Sleep Apnea

Key Takeaways

• Chiari malformation is a rare abnormality in the area where the brain meets the spine.
• Chiari malformation is associated with both central sleep apnea and obstructive sleep apnea.
• The disorder can impact the part of the brain that regulates breathing, contributing to central sleep apnea.
• Chiari malformation can also cause muscle weakness in the airway, which can lead to obstructive sleep apnea.

What Is Chiari Malformation?

A Chiari malformation is an abnormality in certain parts of the brain and upper spine. In Chiari malformation, an area of the brain called the cerebellum and the brainstem are pushed through an opening in the skull and into the spinal canal. There are multiple types of Chiari malformation, classified based on the magnitude of the condition and which parts of the brain are affected.

Chiari Malformation Type 1

In Chiari malformation type 1, the part of the brain known as the cerebellum is shaped abnormally, with sections of it bulging below the opening of the skull where the brain connects to the spinal cord. Type 1 is the most common type of Chiari malformation. While Chiari malformation type 1 doesn’t always cause symptoms, it’s been linked to sleep apnea.

Chiari Malformation Type 2

Chiari malformation type 2 is also called Arnold-Chiari malformation or classic Chiari malformation. In type 2, several regions of the cerebellum are pushed down through the opening in the skull. This type is often accompanied by spinal defects and can interfere with the flow of cerebrospinal fluid between the brain and the spine. This sometimes leads to a buildup of fluid in the brain called hydrocephalus.

Other Chiari Malformation

Rarer types of Chiari malformation have also been identified. Type 3 and type 4 involve more severe abnormalities of the brain and upper spine. 

Although this classification isn’t in wide usage, Chiari malformation type 1.5 may describe some cases. Type 1.5 is similar to types 1 and 2 but without spinal defects and is associated with higher-than-average rates of obstructive sleep apnea (OSA).

Chiari Malformation Symptoms

The severity of Chiari malformation varies widely, and some people with these conditions don’t have any symptoms. When symptoms do occur, they vary based on the amount of pressure on the brain and spinal cord. They can also depend on the way the malformation affects the flow of cerebrospinal fluid, which is the fluid that surrounds these structures. 

Symptoms of Chiari malformation can include: 

• Headache
• Problems with balance
• Neck pain
• Insomnia
• Muscle weakness
• Numbness
• Swallowing problems
• Blurred vision
• Dizziness
• Difficulty with fine motor skills
• Breathing problems

Chiari Malformation Causes

Experts don’t know for certain what causes Chiari malformation to develop, but they have several theories. Some believe that genetic mutations cause abnormal development in the lower part of the brain. Others suspect that too much cerebrospinal fluid around the brain pushes the brain tissue down during fetal development. 

• Abnormal skull anatomy: Some Chiari malformations develop when the skull is small or abnormally shaped, which forces brain tissue into the spinal canal. These abnormalities most commonly happen before birth, although trauma or disease can cause secondary Chiari malformation later in life.
• Neural tube defects: Other Chiari malformations are associated with neural tube defects, which can occur in early pregnancy. The neural tube is what eventually forms into the brain and spinal cord in an embryo and defects can cause a range of problems with the formation of the spine and brain. 
• Other medical conditions: Chiari malformations are also linked to a number of other medical issues, including developmental and genetic conditions like neurofibromatosis, Noonan syndrome, and Robin sequence.

How Common Is Chiari Malformation?

It’s not currently known exactly how common Chiari malformation is, but it’s rare. Recent studies suggest that it’s present in between 1% and 4% of the population. Before MRI was developed in the 1980s, it was difficult to truly diagnose Chiari malformation.

Chiari Malformation and Sleep Apnea

Sleep apnea is frequently seen in people with Chiari malformation types 1, 1.5, and 2. Both central and obstructive sleep apnea are more common in children and adults with Chiari malformation than they are in the general population. 

Chiari Malformation and Central Sleep Apnea

In central sleep apnea (CSA), breathing stops briefly during sleep because the brain doesn’t send proper signals to enable continuous breathing. This can be due to compression of the brainstem caused by a Chiari malformation, which can interfere with the brain’s control of breathing while a person is sleeping. 

Although CSA is rare in the general population, affecting less than 1% of people, it’s common among those who have Chiari malformation. Because CSA is especially rare in children, some experts emphasize that children with central sleep apnea should be tested for Chiari malformation. 

Chiari Malformation and Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) also involves repeated disruptions in breathing during sleep, but this type of apnea is caused by the collapse of the airway. OSA may occur when nerves that control the muscles of the throat are affected by Chiari malformation.

Research also suggests that the more severe Chiari malformation is, the more likely a person is to experience OSA.

How to Diagnose Chiari Malformation

To diagnose Chiari malformation, doctors rely on imaging tests, most commonly MRI. It can’t be detected through blood tests either during pregnancy or after, but it can sometimes be seen on ultrasound images during pregnancy.

Doctors usually start an examination for Chiari malformation by testing a patient’s balance, memory, and motor skills. Brain imaging then allows doctors to examine the structure of the brain and spinal cord to see if there are any abnormalities.

Chiari Malformation Treatment

Doctors may use several different approaches to treat Chiari malformation or manage symptoms caused by it, including sleep apnea. A person’s doctor is in the best position to assess their situation and determine which treatments are most likely to be beneficial. 

• Conservative management: People with Chiari malformation type 1 who don’t have symptoms may be managed conservatively. This means that the doctor keeps an eye on their situation and may perform testing if any symptoms related to Chiari malformation arise. 
• Surgery: Surgery may be appropriate for people with Chiari malformation that cause symptoms. The most common surgery creates more space for the brain and reduces pressure on the spinal cord. 
• Positive airway pressure treatment: Positive airway pressure (PAP) treatments like CPAP and BiPAP can treat obstructive sleep apnea linked to Chiari malformation. 
• Adaptive servo-ventilation: Adaptive servo-ventilation (ASV) assists breathing in people with central sleep apnea associated with Chiari malformation by providing variable air pressure while a person sleeps.

Frequently Asked Questions

Can Chiari malformation get worse?

It’s possible for Chiari malformation to get worse over time, though it’s difficult to predict how the disorder might progress. There’s limited research on how Chiari malformation affects people long-term, but those with no or mild symptoms typically remain stable. 

For people who undergo surgery, symptoms usually improve or remain stable, though symptoms do worsen for a small percentage.

Is Arnold Chiari malformation genetic?

It isn’t currently known whether or not Arnold Chiari malformation is genetic, but there’s a theory called molecular genetic hypothesis that speculates that it might be in some cases. 

Researchers theorize that defective expression of certain genes could lead to the base of the skull developing smaller than usual. Other studies have shown that Arnold Chiari malformation sometimes occurs in more than one member of a family, which could indicate a genetic link. If research eventually shows a genetic link, it could help doctors identify at-risk patients and provide treatment earlier.

Can Chiari malformation cause seizures?

People with Chiari malformation sometimes experience seizures, but it’s rare. Sometimes, Chiari malformation is discovered in patients who undergo an MRI for seizures, though it isn’t always clear if Chiari malformation actually contributed to their seizures. 

Does Chiari malformation make you sleepy?

Chiari malformation may indirectly cause sleepiness.Excessive daytime sleepiness is a common symptom of sleep apnea. Although there’s no evidence that Chiari malformation directly causes sleepiness, the sleep apnea that often accompanies a Chiari malformation is very likely to make a person sleepy. 

Does Chiari malformation affect your sleep?

In addition to disruptions in breathing, Chiari malformation can also contribute to insomnia. In particular, people with Chiari malformation may experience longersleep latency, which means the amount of time it takes to fall asleep. 

Does Chiari malformation cause snoring?

Although not all people with Chiari malformation snore, this condition can lead to breathing problems during sleep that may include snoring. Snoring is also a common symptom of obstructive sleep apnea, which occurs more frequently in people with Chiari malformation.