This surgery is used to treat Chiari Malformation, an abnormality that results in a part of the brain extending into the spinal canal.

The surgeon creates an incision in the back of the head extending down to the upper neck in the midline.  The soft tissue and upper neck muscles are pulled back to expose the skull and first vertebra.  Using a high-speed drill a section of the base of the skull is removed to create more space for the brain.  Then the back arch of the C1 vertebra is moved, known as a laminectomy.  In most cases, more space also needs to be created in the dura.  A Y-incision is created in the dura so that it can be expanded and then a patch of natural or synthetic graft material is placed.

The bone is not replaced.  In some cases, a small strip of titanium mesh may be places across the top portion of the hole in the skull to provide a place for the muscles to reattach.  The muscles are closed and the skin flap is folded back and closed with sutures or surgical staples.