Chiari malformations
Chiari malformations are a group of neurological disorders characterized by the herniation of the cerebellum into the spinal canal, specifically below the foramen magnum. They are classified into four types based on severity, with Type 1 being the most common and often asymptomatic, Type 2 known as Arnold-Chiari malformation occurring primarily in children, and Types 3 and 4 being rare, serious conditions that typically involve significant neurological defects. The malformations can arise from structural defects during fetal development, and in some cases, they may develop after injuries or surgeries to the head and neck.
Symptoms may vary widely, with some individuals experiencing no symptoms at all, while others may suffer from headaches, neck pain, balance issues, and numbness in the limbs. Treatment options depend on the severity of symptoms and may include pain management or decompression surgery to alleviate pressure on the spinal cord and nerves. Although surgery can help reduce symptoms, it is important to note that it does not cure Chiari malformations or reverse any existing nerve damage. Understanding the nature of Chiari malformations can provide valuable insights for those seeking information about this complex neurological condition.
Chiari malformations
ALSO KNOWN AS: Arnold-Chiari malformation
ANATOMY OR SYSTEM AFFECTED: Brain, muscles, neck, nervous system, spine
DEFINITION: A group of disorders where the cerebellum extends below the opening of the spinal canal (the foramen magnum). Chiari malformations are classified according to severity and how much of the brain extends into the spinal canal. Type 1 is the most common and may be asymptomatic, type 2 is considered the classic Chiari malformation, and types 3 and 4 are rare and the most serious.
CAUSES:Structural flaws in the brain and spinal cord during fetal development; for type 1 Chiari malformation, sometimes injury or surgery later in life
SYMPTOMS: May be asymptomatic; headaches that are worse with coughing and straining, neck pain, difficulty swallowing, occasionally difficulty speaking, problems with balance and motion, feeling of numbness in arms and legs
DURATION: Chronic
TREATMENTS: Pain medication, surgery
Causes and Symptoms
Primary or congential Chiari malformations are a result of structural flaws during fetal development of the brain or spinal canal. The classification of Chiari malformations into four types is based on the extent of the structural flaws. Chiari malformations may also occur after surgery of the head and neck area or after an injury; these are considered secondary or acquired Chiari malformations.
Some individuals with type 1 do not have any symptoms and may not even know they have a Chiari malformation. This type is considered the adult form of the disorder because often symptoms first appear in adolescence or adulthood. Headaches, neck pain, balance problems, dizziness, hearing and vision problems, and numbness in the arms and legs are the symptoms that result from the pressure on nerves caused by the herniation of the cerebellum into the foramen magnum. These symptoms may come and go. A secondary condition called a syringomyelia may develop in some cases, and it can cause permanent nerve damage.
Type 2, also known as an Arnold-Chiari malformation, is considered the classic Chiari malformation. In this type, both the cerebellum and part of the brain stem are pushed into the foramen magnum. Type 2 is a pediatric disorder, and it almost always involves a form of spina bifida.
Types 3 and 4, also pediatric disorders, are the most serious forms of Chiari malformations and involve significant brain and neurologic defect. Children with these types do not usually live past two years of age.
Treatment and Therapy
Treatment is not necessary for those individuals who do not have symptoms. Otherwise, treatment is based on the severity of the disorder. Pain medications or nonsteroidal anti-inflammatory drugs (NSAIDs), or both, are used to reduce the pain.
Surgery, specifically some type of decompression surgery, is used to alleviate the pressure on the spinal cord and nerves. Various surgical procedures may be performed to reduce pressure by making more room. One frequently used procedure is a posterior fossa decompression, in which a small piece of the skull at the back of the head is taken out; sometimes a piece of synthetic tissue, called a dura patch, is used to enlarge the area for the brain. Another surgical procedure that is used to relieve pressure and make more room is a laminectomy, in which some of the bony border of the spinal canal is removed.
Other surgical procedures, such as insertion of a shunt for drainage of a syringomyelia or surgical closure of the spinal column in spina bifida, may be necessary. Some surgeries for treatment of the pediatric forms of the disorder are done before birth.
Surgery does not cure Chiari malformations, and it cannot undo the nerve damage that has already occurred. Nevertheless, the various surgical procedures can reduce the pressure and relieve the symptoms. Surgery is not always effective, however, and it is possible that a more severe Chiari malformation may result after surgery.
Bibliography
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