Causes of Chiari Malformation
There are many thoughts as to the exact cause of Chiari Malformation - It is agreed that it is the downward displacement of the cerebellum of at least 5 mm.There has been a lot of changes over the years as to why this displacement occurs and the most highly regarded are mentioned here. This could be caused by genetic mutations, lack of vitamins and nutrients (Folic Acid has been found to affect spinal development). Chiari is generally considered congenital however there has been thought it can be caused later in life due to drainage of spinal fluids during injury herniating the brain. Exposure to harmful substances or infection, this is called secondary or acquired Chiari malformation. However Congenital Chiari is the more common type found.
Chiari malformation Type 1 occurs when the section of the skull (foramen magnum) containing the cerebellum is to small or deformed. This puts pressure on the cerebellum and brainstem causing the lowermost portion called the tonsils of the cerebellum to distend in the upper spinal cord. While Chiari Type 2 is actually a deformity of the central nervous system associated with tethered cord syndrome - where the base of the spine adheres to the spine displacing the cerebellum causing the symptoms.
Chiari II is mostly associated with myelomeningocele. With the cerebellum being pushed into the spinal canal this blocks off the normal flow of the cerebrospinal fluid (CSF) from the brain to the spine. This impaired circulation can lead to blockage of signals being transmitted between your body and brain or lead to a build up of spinal fluid (syringomyelia) in the spinal canal or brain (intracrannial hypertension). Also the pressure on the cerebellum from the skull and lower brainstem can cause neurological signs and symptoms.
Further research into the possible chiari being genetic and its exact causes are still being looked into and researched. It has been noticed that chiari may run in the family and has been seen throughout a family in different generations.
MRI's and Images
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