Causes of Chiari Malformation
Developmental abnormalities primarily cause Chiari malformation, though acquired conditions that alter brain or spinal cord structure or pressure dynamics can also lead to it.. Understanding the causes of Chiari malformation helps explain the wide variation in presentation and progression.
1. Congenital (Primary) Chiari Malformation
Most Chiari malformations are congenital — meaning they are present from birth. What typically cause this is:
- Underdeveloped or misshapen skull bones, particularly at the back of the head, leading to less space for the cerebellum
- Genetic mutations affecting bone or brain development
- Developmental disorders, such as spina bifida, especially in Type II cases
In congenital Chiari malformation, the brain tissue is squeezed downward during fetal development due to the limited space within the skull.
2. Acquired (Secondary) Chiari Malformation | Causes of Chiari Malformation
In rare instances, Chiari malformation may develop later in life due to:
- Head or spinal trauma
- Spinal fluid drainage problems, such as from a lumbar shunt or spinal tap
- Infections or inflammatory diseases affecting brain or spinal tissue
These acquired forms alter the pressure balance or anatomy of the skull and spine, resulting in brain tissue descending into the spinal canal.
3. Structural Brain and Skull Imbalance
The mismatch between brain size and skull volume is a key factor. In some individuals, the cerebellum is not necessarily too large — the skull is simply too small to contain it. This relative crowding forces part of the brain downward.
4. Associated Conditions | Causes of Chiari Malformation
Chiari malformations are often associated with other neurological or skeletal disorders, including:
- Syringomyelia (fluid-filled cavity in the spinal cord)
- Hydrocephalus (excess fluid in the brain)
- Scoliosis (curvature of the spine)
- Ehlers-Danlos syndrome (a connective tissue disorder)
While the exact trigger of congenital Chiari malformation isn’t always known, early diagnosis and genetic insight help guide treatment and family planning.
The causes of Chiari malformation may be complex, but timely recognition of contributing factors can lead to earlier diagnosis and better long-term outcomes.
[Next: Symptoms of Chiari Malformation →]
