Chiari malformation

Chiari malformation is a structural defect of the cerebellum. This is the part of the brain responsible for balance.

Some people with a Chiari malformation may not have any symptoms. Others may have symptoms such as:

dizziness
muscle weakness
numbness
vision problems
headaches
problems with balance and coordination

Chiari malformation affects women more often than men.

Scientists once thought that Chiari malformation only occurred in 1 in 1,000 newborns, but the increased use of diagnostic imaging techniques such as computed tomography and magnetic resonance imaging suggests that the disease may be much more common.

It is difficult to make accurate estimates. This is because some children born with the condition never show symptoms or do not develop symptoms until they reach adolescence or adulthood.

Causes of the Chiari malformations

Chiari malformation usually occurs due to structural defects in the brain and spinal cord. These defects develop during fetal development.

Due to genetic mutations or the mother's diet is deficient in certain nutrients, the recessed bony space at the base of the skull is abnormally small. The result is pressure on the cerebellum. This blocks the flow of cerebrospinal fluid. It is the fluid that surrounds and protects the brain and spinal cord.

Most Chiari malformations occur during fetal development. Much less often, Chiari malformation can occur at a later age. This can happen when too much cerebrospinal fluid is released due to:

injury
infection
exposure to toxic substances

Types of Chiari malformation

There are four types of Chiari malformation:

Type I. This is by far the most common type seen in children. In this type, the lower part of the cerebellum, but not the brainstem, emerges into an opening at the base of the skull. The hole is called the foramen magnum. Normally, only the spinal cord passes through this opening.

Type I is the only type of Chiari malformation that can be acquired.

Type II. This is usually seen only in children born with spina bifida. Spina bifida is the incomplete development of the spinal cord and/or its protective covering.

Type II is also known as "classic" Chiari malformation or Arnold-Chiari malformation. In type II Chiari malformation, the cerebellum and brainstem extend to the foramen magnum.

Type III. This is the most serious form of Chiari malformation. It involves a protrusion or herniation of the cerebellum and brainstem through the foramen magnum and into the spinal cord. This usually causes severe neurological defects. Type III is a rare type.

Type IV. This is an incomplete or underdeveloped cerebellum. Sometimes it is associated with exposed parts of the skull and spinal cord. Type IV is a rare type.

In addition to spina bifida, other conditions sometimes associated with a Chiari malformation include:

Hydrocephalus. Excessive accumulation of cerebrospinal fluid in the brain.
Syringomyelia. A disease in which a cyst develops in the central canal of the spinal cord.
Syndrome tied umbilical cord. A progressive disease in which the spinal cord attaches to the spine.
Rachiocampsis. This includes conditions such as:
Scoliosis (curvature of the spine to the left or right)
Kyphosis (forward curvature of the spine)

Chiari malformation symptoms

Chiari malformation is associated with a wide range of symptoms that vary depending on the type.

Type I Chiari malformation usually causes no symptoms. Most people with this condition are not even aware that they have it, unless they are discovered incidentally during diagnostic imaging.

But if the malformation is severe, type I can cause symptoms such as:

Pain in the lower part of the occiput in the neck; it usually builds up quickly and gets worse with any activity that raises pressure in the brain, such as coughing and sneezing.
Dizziness and problems with balance and coordination
Difficulty swallowing
Sleep apnea

Most children born with Chiari type II malformation have hydrocephalus. Older children with Chiari type II malformation may develop headaches associated with:

coughing or sneezing
bend over
intense physical activity
straining when emptying the bowels

Some of the most common symptoms are related to problems with the functioning of the stem nerves. This include:

weak vocal cords
difficulty swallowing
respiratory disorders
serious changes in the function of the nerves of the throat and tongue

Chiari malformation treatment

If you suspect a Chiari malformation, your doctor will perform a physical examination. The doctor will also check the functions controlled by the cerebellum and spinal cord. These features include:

balance
touch
reflexes
sensation
motor skills

Your doctor may order diagnostic tests, such as:

X-ray
CT scan
Magnetic resonance imaging

Magnetic resonance imaging is the test most commonly used to diagnose Chiari malformations.

If the Chiari malformation does not cause any symptoms and does not interfere with daily life, no treatment is required. In other cases, medications may be used to treat symptoms such as pain.

Surgery is the only treatment that can correct functional defects or stop the progression of damage to the central nervous system.

For Chiari type I and type II malformation, the goals of surgery are to:

Relieve pressure on the brain and spinal cord
Restore normal fluid circulation in and around the area

In adults and children with a Chiari malformation, several types of surgery can be performed. This includes:

Posterior fossa decompression surgery. This involves removing a small portion of the lower part of the skull, and sometimes part of the spine, in order to correct the abnormal bone structure. The surgeon may also open and expand the dura. It is a hard covering of the tissues of the brain and spinal cord. This creates additional space for the circulation of cerebrospinal fluid.
Electrocautery. This uses high-frequency electrical currents to contract the lower part of the cerebellum.
Spinal laminectomy. This is the removal of part of the arched bone roof of the spinal canal. This increases the size of the canal and relieves pressure on the spinal cord and nerve roots.

Additional surgery may be required to correct conditions associated with a Chiari malformation, such as hydrocephalus.