What Is Chiari Malformation?
Chiari (pronounced kee-aa-ree) malformation is a group of conditions where the lower back part of your brain pushes against or into the hole where your spinal cord enters your skull, called the foramen magnum. The lower back part of your brain is called your hindbrain, and in severe cases, parts of the hindbrain are missing. Your hindbrain includes your cerebellum, pons, and medulla oblongata.
- The cerebellum controls your movement, balance, posture, and some aspects of language and attention.
- The pons connects your brain to your spinal cord and controls your unconscious movements and processes, such as breathing and sleeping.
- The medulla oblongata connects your brainstem to your spinal cord and helps control many of your body's vital functions, such as breathing, heart rate, and blood pressure.
Chiari malformation is usually something you're born with. But in some cases, you may develop it as an adult because of a head injury or a tumor in your brain. There are several types, and your symptoms and treatment will depend on which type you have. Most of the time, you will be diagnosed before you're born when your mom goes in for the second-trimester ultrasound. But many people with type I, the most common type, will only discover it as a teen or adult when imaging is done due to symptoms.
If you don't have symptoms or aren't troubled by your symptoms, you may not need any treatment. If you do, you may be able to manage your symptoms with medicine. But if your symptoms are troublesome, you may need to have surgery.
Read on to learn more about the causes, types, symptoms, and treatment for Chiari malformations.
Chiari Malformation Causes
Chiari malformations are structural defects in your brain and spinal cord that happen mostly because of abnormal fetal development. Many people with a Chiari malformation have a smaller posterior fossa than other people. Your posterior fossa is the part of your skull where your cerebellum would normally fit. If your posterior fossa is too small, it may cause your brain to push against and down into your foramen magnum. But researchers don't know exactly why these differences happen during fetal development.
Some families have several people with a Chiari malformation. In this case, the cause may be genetic, although experts don't yet know which genes are involved. You may also have a Chiari malformation due to other developmental conditions, such as:
- Goldenhar syndrome, which is a variant of oculo-auriculo-vertebral spectrum — a condition where your eyes, ears, bones in your face, and spine aren't formed correctly.
- Albright hereditary osteodystrophy (pseudohypoparathyroidism), which is a genetic condition where your body doesn't respond to parathyroid hormone, which causes your bones to form incorrectly.
- Hajdu-Cheney syndrome, a rare genetic condition where your body breaks down your bones. Many people with this condition also have skull deformities.
- Ehlers-Danlos syndrome, a rare genetic condition that affects your connective tissues.
- Achondroplasia, which is a genetic bone growth disorder.
In some cases, Chiari malformations happen after you're born when you get a condition that takes up space in your skull. This is called an acquired Chiari malformation. You may get it due to:
- A tumor in your brain.
- Arachnoid cyst, which is a fluid-filled sac that may form in your brain after a head injury.
- Hematoma, which is a pool of blood in your brain due to head injury.
- Hydrocephalus, which is when too much cerebrospinal fluid builds up in your brain. In some cases, you may develop it after treatment for hydrocephalus with a lumboperitoneal shunt.
- Basilar invagination, which is when a bone in your neck, your second vertebrae, moves upward into your foramen magnum. This may close it or press into your brain stem.
- Tethered cord syndrome, which is when your spinal cord attaches to the wall of your spinal column. This causes your spinal cord to stretch and pull down on your brain.
Many of the signs and symptoms of a Chiari malformation are probably due to an abnormal flow of cerebrospinal fluid in your skull and spinal column. Cerebrospinal fluid is a clear, colorless fluid that surrounds your brain and spinal cord. It nourishes, takes away wastes, and protects them. Chiari malformation may block the flow of cerebrospinal fluid between your brain and spinal cord and may also compress parts of your brain and spinal cord.
Chiari Malformation Types
Doctors classify Chiari malformations based on their structure and how different they are from the typical structure. They usually use imaging tests to determine this. Experts classify the malformations into four main types:
Chiari malformation type I
This is the most common and least severe type. Your doctor may notice it when you're a child or teen when you have imaging for another condition. In this type, the lower part of your cerebellum pushes against the opening at the base of your skull through which your spinal cord passes. This opening is called the foramen magnum.
Chiari malformation type II
You may hear this type also called Arnold-Chiari malformation. In this type, both your cerebellum and brain stem push against your foramen magnum. You may also be missing the tissue that connects the two halves of your cerebellum, or the tissue may only be partly formed.
It usually happens in people with a myelomeningocele. This is a form of spina bifida where your spinal cord and backbone don't close completely before you're born. People with myelomeningocele often have partial or complete paralysis below the neck. People with Chiari type II may also have a condition called hydrocephalus, which is a nervous system disorder caused by a buildup of cerebrospinal fluid deep in your brain.
Chiari malformation type III
This is a rare type that usually shows up when you're an infant (if not before) because it can have debilitating and life-threatening complications. It happens when your cerebellum, brain stem, and sometimes the membranes surrounding your brain, bulge through your foramen magnum into your spinal column. It may cause severe neurological defects, such as mental and physical delays and seizures.
Chiari malformation type IV
This is a very rare type. With this type, your cerebellum isn't completely formed or parts may be missing. Some people may have exposed parts of the skull and spinal cord.
Chiari Malformation Symptoms
These signs and symptoms vary by type and can be very different between individuals.
Type I Chiari malformation may not cause any symptoms. You may only realize you have it when you're a teen or adult while getting imaging for another condition. If you do have symptoms, they may come and go. But if you have compression of your brainstem and spinal cord, you may have neurological symptoms, such as:
- Headache in the lower back of your head (occipital headache) and neck pain. This is the most common symptom. The pain may get worse when you cough, sneeze, strain, or bend over.
- Dizziness and problems with balance
- Muscle weakness
- Loss of pain and temperature sensation in your upper body and arms
- Numbness or tingling in your arms and legs
- V ision problems, such as blurred vision, double vision, and light sensitivity
- Swallowing difficulties
- Hearing loss and ringing in your ears (tinnitus)
- Nausea and vomiting
- Trouble sleeping (insomnia)
- Depression
- Sleep apnea
Symptoms of type II Chiari malformation are usually related to myelomeningocele and hydrocephalus, such as:
- Loss of arm strength
- Involuntary, fast, downward eye movements
- Reduced gag reflex
- Altered breathing patterns, including times when you stop breathing (apnea)
Type III Chiari malformations are very rare, and people born with this may have severe neurological symptoms very early in life. Many people may also have hydrocephalus and other birth anomalies. Type IV Chiari malformations are rarer than type III and the people born with it often have other malformations in their brain and brainstem.
Chiari Malformation Diagnosis
Chiari malformations of types II, III, and IV are usually first identified using fetal sonography during the second-trimester anatomy check. Your obstetrician can then use fetal MRI to see more clearly what is going on.
If you have type I that went unidentified as a fetus, your doctor will likely start by asking about your symptoms and will perform a physical exam, including a neurological exam. During a neurological exam, your doctor tests for things such as your:
- Sense of balance
- Ability to touch and perceive sensations
- Reflex strength and speed
- Ability to perform motor skills
- Ability to drink fluids or swallow thickened food
- Ability to sleep
If your doctor suspects Chiari malformation, they will likely order imaging tests, such as:
- MRI is the most common test doctors use to diagnose Chiari malformation. This will show if you have a buildup of cerebrospinal fluid in your brain or spinal column or loss of brain tissue. They may also ask for a cine MRI, which is a specialized test that will allow them to see how your cerebrospinal fluid moves in real time.
- Myelography, if you can't have an MRI.
- X-ray, which can show abnormalities in your skull and spine
- CT scan, which may help your doctor further determine if you have bony abnormalities at the base of your skull
Chiari Malformation Treatment
You may not need treatment if the Chiari malformation doesn't cause symptoms or interfere with your daily life or activities. If you have symptoms, your doctor can prescribe medications and devices to help. For instance, your doctor may prescribe a nonsteroidal anti-inflammatory drug (NSAID), muscle relaxers, or a cervical collar to help ease headaches and neck pain.
If you have persistent symptoms and your imaging tests show that your cerebellum is pushing through the foramen magnum, your doctor may suggest surgery to correct the functional defects and stop progressive damage to your central nervous system. The goal of surgery is to:
- Relieve pressure on your brain and spinal cord
- Restore normal cerebrospinal fluid circulation
Chiari malformation surgery
According to one study, more than 80% of adults who have surgery have a significant reduction in their symptoms. Your doctor may recommend one of several types of surgery, including:
Posterior fossa decompression surgery. This is the standard procedure your doctor may suggest. During this surgery, your surgeon will remove a small part at the bottom of your skull and sometimes part of your cervical spine to correct the irregular bony structure. The surgeon also may open and widen the membranes (called dura) that surround your brain and spinal cord. This makes additional space so your cerebrospinal fluid can circulate.
Electrocautery. Some neurosurgeons recommend this procedure, which uses high-frequency electrical currents to shrink the lower part of the cerebellum so that it retracts out of the foramen magnum.
Spinal laminectomy. During this procedure, a part of your spinal canal is removed to increase the canal's size and reduce pressure on your spinal cord and nerve roots.
If you have hydrocephalus, your doctor may recommend you have a shunt placed to drain the excess cerebrospinal fluid away from your brain to another part of your body where it can be absorbed. In some cases, this alone can relieve your symptoms.
Chiari Malformation Complications
In addition to spina bifida, other conditions sometimes associated with Chiari malformations include:
Hydrocephalus. An excessive buildup of cerebrospinal fluid in your brain.
Syringomyelia. A disorder in which a cyst develops in your spinal cord's central canal.
Tethered cord syndrome. A progressive disorder in which the spinal cord attaches itself to your bony spine.
Spinal curvature. This includes conditions such as:
Living With Chiari Malformation
Your symptoms may come and go, so it's important to be kind and patient with yourself. Don't be afraid to ask family and friends for help on the days you need support.
Consider joining an organization or support group for people with Chiari malformation. It can be helpful to interact with people who are experiencing the same symptoms and challenges. For people in the U.S., the American Syringomyelia & Chiari Alliance Project has online support groups, telephone support, and local support groups.
You can help support yourself by practicing good lifestyle habits, such as:
Eat healthy foods most of the time. Studies show that the Mediterranean diet has health benefits for most people. This diet includes lots of fruits, vegetables, nuts, whole grains, fish, and healthy oils (such as olive oil). Avoid eating processed foods as much as possible. And drink plenty of water. Doctors usually recommend about six to eight 8-ounce glasses of water per day for most people. Staying hydrated can help keep headaches and fatigue at bay when you're managing a health condition.
Exercise regularly. Low-impact exercises, such as tai chi and walking, are less likely to make your symptoms worse. Yoga and tai chi may also help reduce your stress levels, improve your balance, and strengthen your muscles. Ask your neurologist and neurosurgeon if it's OK for you to participate in high-impact or group sports.
Get good sleep regularly. Sleep problems, such as insomnia, can be one of your more troublesome symptoms. But here are some steps to ensure you get good sleep:
- Go to bed and get up at the same time every day, even at the weekends or on your days off.
- Keep your bedroom quiet, dark, and tidy so it's easier to drift off to sleep.
- Relax or wind down before bedtime. Try meditating or taking a bath.
- Eat a small snack or drink something with the amino acid tryptophan right before bed. This can help you feel naturally sleepy.
- Avoid caffeine and nicotine within a few hours of your bedtime.
- Choose a supportive pillow so headaches and neck pain don't keep you awake. You can find supportive, specially shaped pillows online. Some people prefer sleeping with a travel pillow to support their neck.
Takeaways
Chiari malformations are structural defects in your brain and spinal cord that you're usually born with. In many cases, you will be diagnosed before you're born when your mom goes in for the second-trimester ultrasound. There are several different types. Your symptoms and treatment will depend on which type you have. Most people have type I, which may or may not have symptoms. If you do have symptoms with type I, your doctor may be able to treat you with medicine. In some cases, you may need surgery to correct the defect.
Chiari Malformation FAQs
What is the life expectancy of someone with Chiari malformation?
This depends on the type you have and your general health. If you have no symptoms or only mild symptoms, you're likely to have a normal life expectancy. If you have severe symptoms, ask your doctor what to expect. Unfortunately, people with type III or IV may have severe neurological defects and may not live past childhood.
