What causes Chiari malformations?
A Chiari malformation can be caused by defects that take place as the fetus is developing. These defects may be the result of genes (hereditary) or lack of vitamins and nutrients in the pregnant woman’s diet. When Chiari malformations occur in the womb, the condition is known as primary CM or congenital CM. Chiari malformations can also develop years later because of: • injury to the spine, • infection, or • exposure to harmful substances. Different Types In Type I, the lower part of the cerebellum extends into the opening to the spinal canal. Type I CM is the most common form of the disease. It may not cause any symptoms. It is often diagnosed by accident, as a patient is being examined for some other condition. In the other 3 types of CM, the patient notices symptoms. (See Symptoms below). Type II CM is known as classic CM. In this condition, both the cerebellar and brainstem tissue extend into the spinal canal opening. Usually Type II CM includes a form of spina bifida known as myel
