Chiari I Malformation - Cause and Effect
Chiari I malformation can be caused by a congenital condition or in some instances from an event such as infection or injury. The effect of Chiari I malformation can cause multiple physical problems depending on the degree of the malformation and may necessitate surgery. In addition, an asymptomatic Chiari I malformation can become symptomatic when aggravated or made worse by injury with effect of causing symptoms that did not exist before.
Chiari I malformation is a condition where the lowest part of the brain, the cerebellum, hangs down into an opening in the skull known as the foramen magnum. The part of the cerebellum that hangs down when someone is suffering from Chiari I malformation is known as cerebellar tonsils and this condition is known as tonsiler herniation.
The displaced downwardly hanging cerebellar tonsils can cause blockage of the normal flow of the cerebral spinal fluid (CSF) causing symptoms.
In more severe cases a syrinx can occur causing cyringomyelia which is a condition where a cavity is created that fills with CSF.
Most Chiari I malformations are caused by abnormalities in the structure of the brain and spine and are congenital. However, in some cases Chiari I malformations can be caused by injury or infection where pressure can cause the cerebellar tonsils to hang down (tonsiler herniation).
Asymptomatic congenital Chiari I malformations can be aggravated or made worse by trauma or injury causing the Chiari I malformation to become symptomatic.
The effect of symptomatic Chiari I malformation can cause the following problems:
- Swallowing problems
- Vision problems
- Spasticity of the limbs
- Sudden "drop attacks" where the legs seem to buckle for no reason
The most definitive test in diagnosing a Chiari I malformation is magnetic resonance imaging (MRI) to detect the location of the cerebellum and spinal cord compression.
If the symptoms and malformation are not that severe the Chiari I malformation can be treated with medication including pain medication for headaches and anti-inflammatory medication.
If the effect of the Chiari I malformation causes severe symptoms then surgery is recommended when it becomes necessary to relieve the pressure on the cerebellum and spinal cord to reestablish circulation of the CSF. The procedure involves dissecting the muscle at the base of the skull, opening a small window of bone and then often removing some of the bone on top of the spinal cord as well. The second part of the operation can involve opening the dura, the sack that encloses the brain, to release the pressure and then place a patch on the area. The bone is not put back on, the muscle is closed and the skin is closed achieving a mechanical decompression of the area.