Posterior fossa decompression, spinal fusion, shunting and transoral decompression are types of surgical procedures used to treat a Chiari I malformation, explains Mayfield Chiari Center. Surgery is only advisable for patients with severe symptoms or a fluid-filled cyst, called a syrinx, inside of the spinal cord.
The purposes of surgery to correct a Chiari I malformation are to relieve brainstem compression and eliminate or control symptoms resulting from herniated cerebellar tonsils, states Mayfield Chiari Center. During posterior fossa decompression, a surgeon removes portions of bone at the back of the skull and spine, thereby creating a wider space for the brainstem and cerebellar tonsils. Some patients with spinal instability also require a spinal fusion procedure in addition to posterior fossa decompression. To perform spinal fusion, the surgeon inserts rods and screws to provide the skull and neck vertebrae with additional structural support.
Shunting is a surgical procedure performed to reroute the flow of cerebrospinal fluid, or CSF, in Chiari I malformation patients, notes Mayfield Chiari Center. A surgeon uses a shunt, which is a flexible tube featuring a one-way valve, to redirect the CSF in the correct direction. There is a chance of the shunt later becoming clogged or dislodged in the patient's body, requiring an additional surgery. Transoral decompression is another surgery for Chiari I. During this procedure a surgeon removes a bone called the odontoid, or C2 vertebrae, in the case of bone abnormalities.