WHAT IS A CRANIOTOMY?
Craniotomy is a surgical procedure in which a piece of the skull is removed so the surgeon may access the brain beneath, for the treatment of a variety of neurological disorders. The cut-away portion – called the bone flap – may be small or large, and is typically put back in place after surgery on the brain is finished and before the incision closed.
There are three types of craniotomies. They include:
- Craniectomy: A surgical procedure that removes part of the skull permanently.
- Endoscopic craniotomy: A lighted scope with a camera is inserted through a small incision in the skull
- Stereotactic craniotomy: A surgical procedure where lesion, frequently a brain tumor, is removed with assistance of image guidance, that is previously obtained images (usually an MRI/CT scan) are used to pinpoint the part of the brain that needs to be treated.
WHY IS CRANIOTOMY ADVISED?
There are several different conditions that may require a craniotomy, including the following:
- Brain tumors
- Aneurysms (blood vessel rupture)
- Skull fractures
- Edema/swelling of the brain
- Foreign object removal
- Hematomas (blood clots)
In addition to providing access to the brain, a craniotomy also allows a surgeon to inspect the brain for abnormalities, perform a biopsy or relieve pressure inside the skull.
HOW IS A CRANIOTOMY PERFORMED?
Patients are brought to the operating room, where the anaesthesia personnel will continue to closely monitor their vital signs.
In the operating theatre patient will be positioned on an operating table and the head will be held firmly by a special device featuring three pins that are placed onto the outer surface of the skull. A neuronavigation system (like a satellite navigation system) will be used together with the pre-operative scan to precisely locate the site of the tumour, which can then be marked on the scalp. An incision (cut) can then be marked and a very small amount of patient’s hair will be shaved along the line of the incision. The area will then be cleaned with antiseptic solutions and surrounded by surgical drapes.
The skull will be exposed by making an incision in the scalp and a high-speed drill will then be used to make a small burr hole through the skull to reveal the underlying dura (thick membrane surrounding the brain). A special drill (craniotome) is then used to cut a disc of bone (bone flap), which is removed from the dura. The dura can then be incised to reveal the underlying brain (and tumour). If the tumour lies on the surface of the brain (as with a meningioma) it will be carefully separated from the brain and removed. If the tumour is inside the brain, a cut will be made in the surface of the brain substance down to the surface of the tumour so that it can be removed.
Some tumours (meningiomas, for example) may be able to be removed in their entirety. For many intrinsic tumours (gliomas, for example) the will be aimed to remove as much of it as safely possible. In this case, there will inevitably be microscopic remnants of the tumour left in the surrounding brain. After the tumour has been removed, all bleeding is stopped and the dura is closed with sutures. The bone flap is replaced with three mini-plates and the scalp is closed with staples. The wound is then dressed and sometimes a head bandage is applied.