According to the Chiari and Syringomyelia Foundation, primary CMs are much more common than secondary CMs. While patients with the primary type are born with the condition, secondary CMs are caused later in life by a mass in the brain or excessive drainage of spinal fluid. Primary CMs can be caused by birth defects, lack of vitamins in the mother’s diet while pregnant, or a gene mutation. Some children born with this condition may not show symptoms until adolescence.
