Chiari decompression surgery involves the removal of bone at the back of the skull to expand the foramen magnum (the hole in the base of the skull through which the spinal cord passes) and create space for the brain. Chiari decompression surgery aids in creating more space for the cerebellum and releasing any pressure and/or compression. Some surgeons compare it to letting out the waistband on a pair of pants.
The surgeon may recommend to include a spinal fusion in certain patients with instability of the spine due to conditions such as scoliosis, Ehler-Danlos syndrome, or other bone-related issues. Inserted rods, screws, and devices adhere to the fusion to ensure positive structure reinforcement of the fusion to the skull and neck vertebrae.
Colored areas represent bone to be removed.
The patient lies on the operating table and the doctor administers anesthesia. Once asleep, the patient’s head rests within a suspension apparatus that attaches to the table and holds it in comfortable and fixed position during surgery. The surgeon then shaves a one inch strip along the scalp, prepped with an antiseptic to prepare for the incision.
The neurosurgeon creates a small skin incision through the neck muscles to gain access to the skull and top of the spine. The skin incision is about 3 inches long . The skin and muscles are lifted off the bone and folded back.
The surgeon removes a small area of skull at the back of the patient’s head (suboccipital craniectomy). Additionally, if necessary, the surgeon may opt to remove the bony arch of the C1 vertebra (laminectomy), exposing the protective covering of the brain and spinal cord called the dura. This bone removal usually relieves compression of the tonsils.
Next, the surgeon opens the dura to view the tonsils and cisterna magna. The cisterna magna (or cerebellomedullaris cistern) is one of three principle openings in the subarachnoid space between the arachnoid and pia mater layers of the meninges surrounding the brain. The openings are collectively referred to as the subarachnoid cisterns. Some surgeons perform a Doppler ultrasound study during surgery to determine if opening the dura is necessary. Sometimes bone removal alone may restore normal CSF flow.
Depending on the size of herniation, the stretched and damaged tonsils may be shrunk with electrocautery, eliminating blockage of CSF flow out of the 4th ventricle.
A patch of synthetic material or the patient’s own pericranium (a piece of deep scalp tissue just outside the skull) is sutured into place (Fig. 6). This patch enlarges the dura and the space around the tonsils. The dural patch is sutured in a watertight fashion. The suture line is covered with a dural sealant to prevent CSF leak.
The strong neck muscles and skin are sutured together. A dressing is placed over the incision.
Please be sure to follow all recovering instructions delivered by your surgeon. In general, patients can expect to return to work in 4 to 6 weeks. Within 6 months to a year, a follow up MRI will review the progress of the surgery.