What Is Chiari Malformation?
Chiari Malformation is a condition in which the bony space enclosing the lower part of the brain is smaller than normal.
Crowding causes the cerebellar tonsils to push through the skull and down into the spinal canal. The herniated tonsils block the normal flow of Cerebrospinal Fluid (CSF). Instead of moving in an easy, pulsating movement through this opening, the fluid begins to force its way through pushing the tonsils down even farther and exerting pressure on the brainstem and spinal cord.
Symptoms may not appear until late childhood or adulthood, causing severe headache, neck pain, dizziness, numbness in the hands, and sleep problems.
Treatment options depend on the type of malformation and severity of symptoms. If symptoms are severe or worsening, surgery may be recommended to remove a part of the skull bone and create space for the cerebellum and brainstem.
Types of Chiari malformations include:
Treatment options vary depending on the severity of symptoms, the extent of tonsillar herniation, and the presence of other conditions such as syringomyelia.
Surgery is advised for those with moderate to severe symptoms or with a Syrinx. The goals of surgery are to stop or control the progression of symptoms caused by herniation of the cerebellar tonsils, and relieve compression of the brainstem.
Our surgeons at Salus treat Chiari malformations by performing a POSTERIOR FOSSA DECOMPRESSION SURGERY
Chiari decompression surgery is a CRANIOTOMY surgical procedure performed to treat a Chiari malformation and syringomyelia. Bone at the back of the skull and spine is removed to widen the foramen magnum. The dura overlying the tonsils is opened and a patch is sewn to expand the space. The goals of surgery are to control the progression of symptoms, relieve compression of the brainstem and spinal cord, and restore the normal flow of cerebrospinal fluid (CSF). After surgery, symptoms related to the blockage of CSF should decrease as flow normalizes.
THE PROCEDURE
You will lie on the operating table and be given anesthesia. Once asleep, your head will be placed in a 3-pin skull-fixation device, which attaches to the table and holds your head in position during surgery. An inch wide strip of hair is shaved along the planned incision. The scalp is prepped with an antiseptic.
An incision is made in the skin, down the middle of the neck, allowing the surgeon to gently spread the muscles apart. The skin incision is about 3 inches long. The skin and muscles are lifted off the bone and folded back, giving the surgeon a clear view of the skull and the top of the spine.
The surgeon removes a small section of skull at the back of your head (suboccipitalcraniectomy). In some cases the bony arch of the C1 vertebra may be removed (Laminectomy). These steps expose the protective covering of the brain and spinal cord called the dura. Bone removal relieves compression of the tonsils.
Next, the surgeon opens the dura to view the tonsils and Cisterna Magna. 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. This shrinkage ensures that there is no blockage of CSF flow out of the 4th ventricle.
A patch of synthetic material or the patient’s pericranium (a piece of deep scalp tissue just outside the skull) is sutured into place. This patch enlarges the dura opening 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.
You will wake up in the recovery area called the post-anesthesia care unit (PACU). Your throat may feel sore from the tube inserted to assist your breathing during surgery. Once awake, you’ll be moved to your room. Blood pressure, heart rate, and respiration will be monitored. If you feel nausea or headache after surgery, medication can be given. When your condition stabilizes, you will be discharged in the care of your family or a caregiver, usually 2 or 3 days after surgery.