Chiari malformations affect females more often than males.
Scientists once believed that Chiari malformations occurred in only 1 in every 1,000 births. But the increased use of diagnostic imaging techniques such as CT scans and MRIs suggests that the condition may be much more common.
Accurate estimates are difficult to make. That's because some children who are born with the condition either never develop symptoms or don't develop symptoms until they reach adolescence or adulthood.
Symptoms of Chiari Malformations
Chiari malformation is associated with a wide range of symptoms which vary by type.
Type I Chiari malformation usually causes no symptoms. Most people with the condition don't even know that they have it unless it is incidentally discovered during a diagnostic imaging test.
But if the malformation is severe, type I may cause symptoms such as:
Pain in the lower back of the head into the neck; it usually develops quickly and intensifies with any activity that increases pressure in the brain, such as coughing and sneezing.
Dizziness and problems with balance and coordination
Swallowing difficulties
Sleep apnea
Most children born with type II Chiari malformation have hydrocephalus. Older children with type II Chiari malformation may develop head pain associated with:
Some of the most common symptoms are linked to problems with the function of nerves in the brain stem. These include:
weakness of vocal cords
swallowing difficulties
breathing irregularities
serious changes in the function of nerves in the throat and tongue
Treatment of Chiari Malformations
If a Chiari malformation is suspected, a doctor will perform a physical exam. The doctor will also check functions controlled by the cerebellum and spinal cord. These functions include:
balance
touch
reflexes
sensation
motor skills
The doctor may order diagnostic tests, such as:
X-ray
CT scan
MRI
An MRI is the test most often used to diagnose Chiari malformations.
If Chiari malformations cause no symptoms and do not interfere with activities of daily living, no treatment is necessary. In other cases, medications can be used to manage symptoms such as pain.
Surgery is the only treatment that can correct functional defects or stop progression of damage to the central nervous system.
In both type I and type II Chiari malformations, the goals of surgery are to:
Relieve pressure on the brain and spinal cord
Re-establish normal fluid circulation through and around the area
In adults and children with Chiari malformations, several types of surgery can be performed. These include:
Posterior fossa decompression surgery. This involves the removal of a small portion of the bottom of the skull and sometimes part of the spinal column to correct the irregular bony structure. The surgeon also may open and widen the dura. That's the firm covering of the brain and spinal cord tissues. This creates additional space for the cerebrospinal fluid to circulate.
Electrocautery. This uses high-frequency electrical currents to shrink the lower part of the cerebellum.
Spinal laminectomy. This is the removal of part of the arched, bony roof of the spinal canal. This increases the canal's size and reduces pressure on the spinal cord and nerve roots.
Additional surgical procedures may be needed to correct conditions associated with Chiari malformations such as hydrocephalus.
Surgery usually results in a significant reduction of symptoms and a prolonged period of remission. According to Children's Hospital in Boston, which specializes in the treatment of Chiari malformations, surgery virtually eliminates symptoms in 50% of pediatric cases. Surgery substantially reduces symptoms in another 45% of cases. Symptoms are stabilized in the remaining 5%.