What is the definition of Chiari Malformation Type 2?
Chiari malformation type 2 (CM type II) is a type of Chiari malformation in which both the cerebellum and brain stem tissue extend into the foramen magnum (the hole at the skull base for passing of the spinal cord). CM type II is usually accompanied by a myelomeningocele (a form of spina bifida that occurs when the spinal canal and backbone do not close before birth), which can result in partial or complete paralysis of the area below the spinal opening. While the severity of CM type II can vary greatly, it can potentially cause severe, life-threatening complications during infancy or childhood.
The exact cause of CM type II is not known but it appears to be due to defects in the brain and spinal cord that occur during fetal development. Treatment includes surgery to ease symptoms and/or stop the progression of damage to the nervous system. For most people, surgery improves or stabilizes symptoms. Some people may require more than one surgery.
What are the alternative names for Chiari Malformation Type 2?
- Arnold-Chiari malformation
- Chiari type II malformation
- Chiari malformation type II
- Arnold Chiari malformation type II
What are the current treatments for Chiari Malformation Type 2?
People with Chiari malformation type II are typically treated with surgery. Surgery may include closure of open neural tube defects shortly after birth, treatment for hydrocephalus (most often by use of a shunt), and posterior fossa decompression (creating more space for the cerebellum and relieving pressure on the spinal cord). Medical issues may involve management of neurogenic bowel and bladder, neonatal feeding difficulties, respiratory failure, and apnea.
As with any form of surgery, there are risks associated with surgery to treat Chiari malformations. Sometimes, surgery leads to no improvement or even worsening of symptoms. For example, if nerve injury in the spinal canal has already occurred, surgery will not reverse the damage. However, most people who have surgery have improvement of symptoms afterwards. Even if symptoms do not improve significantly, surgery might prevent existing symptoms from worsening.
What is the outlook (prognosis) for Chiari Malformation Type 2?
The long-term outlook depends on the nature of the malformation and the symptoms present in each person. Although some people experience a reduction of symptoms, there is no guarantee that surgery will help every person. Nerve damage that has already occurred usually cannot be reversed with surgery, and pain from nerve damage can be difficult to treat. Some people may need repeat surgeries.
Is Chiari Malformation Type 2 an inherited disorder?
Chiari malformation type 2 usually occurs sporadically (in people with no family history of the condition). However, the exact cause is not known. Genes may play a role in predisposing a person to the condition, but environmental factors (such as lack of proper vitamins or nutrients in the maternal diet during pregnancy) may also contribute to the condition.
There have been reports in the medical literature of families in which more than one family member had a Chiari malformation. However, limited information specific to familial cases of Chiari malformation type 2 is available.