Craniotomy and craniectomy are surgical procedures. They involve removing part of the skull to treat conditions that affect the brain. The main difference between the two surgeries is what happens to the piece of bone that is removed.
A craniotomy is a surgical procedure that temporarily removes a section of skull to reach the brain. After the treatment to the brain, the skull bone flap is replaced and secured with tiny plates and screws during the same surgery. Rarely, larger pieces of metal or plastic also are used.
Craniotomy
During a craniotomy, a piece of skull is removed to expose the tough covering over the brain, known as the dura mater, and the brain.
Craniotomy is used to:
- Remove brain tumors.
- Repair bulging blood vessels called aneurysms or treat bleeding in the brain.
- Remove blood clots.
- Treat seizures.
- Treat blood vessels that did not form properly, called vascular malformations.
- Relieve pressure from brain swelling due to injury or stroke.
A craniectomy is similar to a craniotomy but with one key difference. The piece of skull bone that is removed is not replaced right away. The skull is left open, often to allow the brain room to swell without being squeezed. This sometimes is called a decompressive craniectomy.
Craniectomy usually is done in emergencies when brain swelling is severe. This may include:
- Traumatic brain injury.
- A major stroke affecting the middle cerebral artery, one of the brain's major blood vessels.
- High pressure inside the skull that doesn't get better with medicine or with a ventilator to help the person breathe.
A craniectomy also may be used in some planned brain surgeries. It's done when leaving the bone off or replacing it with other tissue can help protect the brain during recovery.
How a craniotomy is performed
During a craniotomy, a neurosurgeon cuts through the scalp and temporarily removes a section of the skull, called a bone flap, to access the brain. After the condition is treated, the bone flap is replaced and secured with plates and screws.
People who have a craniotomy are usually under general anesthesia. This means they are in a sleeplike state. Sometimes, an "awake craniotomy" may be used to monitor brain function during the procedure. This procedure uses local anesthesia, and the care team may provide light intravenous sedation.
After surgery, CT scans are usually used to check results. These scans show the bone flap in place and the small plates and screws used during the procedure.
How a craniectomy is performed
During a craniectomy, a section of the skull is removed, but it's not replaced right away. This allows the brain room to swell without being squeezed.
A second surgery, called a cranioplasty, may be needed later to repair the skull. This involves replacing the missing bone with the original bone or with an artificial material. At Mayo Clinic, the neurosurgery and plastic surgery teams often work together when artificial materials are used to create a custom implant that fits the shape of the skull.
Cranioplasty typically is done after brain swelling has gone down, usually several weeks to months later.
After surgery, CT scans are used to check results. These scans show a visible area where the skull bone is missing.
What is a burr hole and how is it different from neuroendoscopy?
Not all brain procedures require removing a large section of the skull.
A burr hole is a small opening drilled into the skull. The opening is usually about the size of a small coin. Unlike a craniotomy or craniectomy, a burr hole doesn't involve removing a large bone flap. Burr holes are minimally invasive. They are used to drain blood or to insert drains or shunts. They also are used to take tissue samples for testing in a lab, called a biopsy.
Neuroendoscopy also is minimally invasive. It uses a thin tube with a camera, called an endoscope, to see inside and reach the brain. The tube may go in through a small opening in the skull or through a natural pathway, such as the nose or mouth.
Main differences at a glance
In simple terms, both craniotomy and craniectomy involve removing part of the skull to treat the brain. In a craniotomy, the bone is put back right away. In a craniectomy, it's left off for a period of time to protect the brain and is usually replaced later. Knowing this difference can make it easier to understand your care and what to expect.
