A craniotomy is the surgical removal of part of the bone from the skull to expose the brain for surgery. The surgeon uses special tools to remove the section of bone (the bone flap). After the brain surgery, the surgeon replaces the bone flap and attaches it to the surrounding bone with small titanium plates and screws. If part of the skull bone is removed and not replaced right away, it is called craniectomy. This is done if swelling is likely after brain surgery or if the skull bone flap can't be replaced for other reasons. After a few weeks to months, you may have a follow-up surgery called a cranioplasty. During a cranioplasty, the missing piece of skull will be replaced with your original bone, a metal plate, or a synthetic material.
For some craniotomy procedures, doctors use MRI or CT scans. Imaging helps guide the doctor to the exact place in the brain that is to be treated. When computers and imaging are combined to make 3-D pictures, it called image-guided craniotomy or stereotactic craniotomy.
A craniotomy can be done with various tools that help the surgeon see the area of the brain. These include loupes, a microscope, high-definition cameras, or an endoscope. A craniotomy with an endoscope involves putting a lighted scope with a camera into the brain through a small hole in the skull.
The extended bifrontal craniotomy is a traditional skull base approach used to target difficult tumors toward the front of the brain. It is based on the concept that it is safer to remove extra bone than to unnecessarily manipulate the brain.
The extended bifrontal craniotomy involves making an incision in the scalp behind the hairline and removing the bone that forms the contour of the orbits and the forehead. This bone is replaced at the end of surgery. Temporarily removing this bone allows surgeons to work in the space between and right behind the eyes without having to unnecessarily manipulate the brain.
Supra-orbital craniotomy (often called "eyebrow" craniotomy) is a procedure used to remove brain tumors. In this procedure, neurosurgeons make a small incision within the eyebrow to access tumors in the front of the brain or pituitary tumors . This approach is used instead of endonasal endoscopic surgery when a tumor is very large or close to the optic nerves or vital arteries.
Retro-sigmoid craniotomy (often called "keyhole" craniotomy) is a minimally-invasive surgical procedure performed to remove brain tumors. This procedure allows for the removal of skull base tumors through a small incision behind the ear, providing access to the cerebellum and brainstem. Neurosurgeons may use this approach to reach certain tumors, such as meningiomas and acoustic neuromas (vestibular schwannomas).
The orbitozygomatic craniotomy is a traditional skull base approach used to target difficult tumors and aneurysms. It is based on the concept that it is safer to remove extra bone than to unnecessarily manipulate the brain.
A translabyrinthine craniotomy is a procedure that involves making an incision in the scalp behind the ear, then removing the mastoid bone and some of the inner ear bone (specifically, the semicircular canals which contain receptors for balance). The surgeon then finds and removes the tumor, or as much of the tumor as possible without risk of severe damage to the brain.
Depending on the underlying problem being treated, the surgery can take 3 to 5 hours or longer.
Step 1: prepare the patient
You will lie on the operating table and be given general anesthesia. Once you are asleep, your head is placed in a 3-pin skull fixation device that attaches to the table and holds your head absolutely still during surgery. A brain-relaxing drug called mannitol may be given.
If image-guidance is used, your head will be registered with the infrared cameras to correlate the “real patient” to the 3D computer model created from your MRI scans. The system functions as a GPS to help plan the craniotomy and locate the lesion. Instruments are detected by the cameras and displayed on the computer model.
Step 2: make a skin incision
The incision area of the scalp is prepped with an antiseptic. Skin incisions are usually made behind the hairline. A hair sparing technique is used, where only a 1/4-inch wide area along the proposed incision is shaved. Sometimes the entire incision area may be shaved.
Step 3: perform a craniotomy, open the skull
The skin and muscles are lifted off the bone and folded back. Next, small burr holes are made in the skull with a drill. The burr holes allow entrance of a special saw called a craniotome. Similar to using a jigsaw, the surgeon cuts an outline of a bone window. The cut bone flap is lifted and removed to expose the protective covering of the brain called the dura. The bone flap is safely set aside and will be replaced at the end of the surgery.
Step 4: expose the brain
The dura is opened to expose the brain. Retractors may be used to gently open a corridor between the brain and skull. Neurosurgeons use magnification glasses, called loupes, or an operating microscope to see the delicate nerves and vessels.
Step 5: correct the problem
Enclosed inside the bony skull, the brain cannot be easily moved aside to access and repair problems. Neurosurgeons use a variety of very small instruments to work deep inside the brain. These include long-handled scissors, dissectors and drills, lasers, and ultrasonic aspirators (uses a fine jet of water to break up tumors and suction up the pieces). In some cases, evoked potential monitoring is used to stimulate specific cranial nerves while the response is monitored in the brain. This is done to preserve function of the nerve during surgery.
Step 6: close the craniotomy
After the problem has been removed or repaired, any retractors are removed, and the dura is closed with sutures. The bone flap is put back in its original position and secured to the skull with titanium plates and screws. The plates and screws remain permanently to support the area, and they sometimes can be felt under your skin. A drain may be placed under the skin for a couple of days to remove blood or fluid from the area. The muscles and skin are sutured back together. A soft adhesive dressing is placed over the incision.
You will be given a follow-up appointment 10 to 14 days after surgery. The recovery time varies from 1 to 4 weeks depending on the underlying disease being treated and your general health. Full recovery may take up to 8 weeks. Walking is a good way to begin increasing your activity level. Do not overextend yourself, especially if you are continuing treatment with radiation or chemotherapy. Ask your surgeon when you can expect to return to work.
You will be transferred to the recovery area for approximately one hour and then to the neurosurgery ward where observations will be performed regularly. These will include an assessment of your conscious level, examination of your pupil responses, tests of your limb strength and checks on your pulse, blood pressure and respirations.
You may have some headaches, which will lessen with time, and you will feel tired and need to rest at home. If you are taking steroids, the dose will slowly be reduced, as prescribed by your surgeon.
As with any surgical procedure, complications may occur. Brain surgery risk is tied to the specific location in the brain that the operation will affect. For example, if the area of the brain that controls speech is operated on, then speech may be affected. Some more general complications include, but are not limited to, the following: