A craniotomy is the surgical removal of part of the bone from your skull to expose the brain. Specialized tools are used to remove a section of bone called a bone flap. The bone flap is temporarily removed, then replaced after the brain surgery has been performed. A craniotomy is commonly performed as part of surgery to remove a brain tumor.

Some craniotomy procedures may utilize the guidance of computers and imaging (magnetic resonance imaging [MRI] or computerized tomography [CT] scans) to reach the precise location within the brain that is to be treated. This technique requires the use of a frame placed onto the skull, called a halo, or a frameless system using superficially placed markers on the scalp. When either of these imaging procedures is used along with the craniotomy procedure, it is called stereotactic craniotomy.

Other uses include a stereotactic biopsy of the brain (in which a needle is guided into an abnormal area so that a piece of tissue may be removed for examination under a microscope), stereotactic aspiration (removal of fluid from abscesses, hematomas or cysts) and stereotactic radiosurgery (such as Gamma Knife radiosurgery).

An endoscopic craniotomy is a type of craniotomy that involves the insertion of a lighted scope with a camera into the brain through a small incision in the skull. Aneurysm clipping is another surgical procedure that may require a craniotomy.

A cerebral aneurysm (also called an intracranial aneurysm or brain aneurysm) is a bulging weakened area in the wall of an artery in the brain, resulting in an abnormal widening or ballooning. Because of the weakened area in the artery wall, there is a risk for rupture (bursting) of an aneurysm. Placement of a metal clip across the "neck" of an aneurysm isolates an aneurysm from the rest of the circulatory system by blocking blood flow, thereby preventing rupture.

Craniectomy is a similar procedure that involves the removal of a portion of the skull. This is done if swelling is likely after brain surgery or if the skull bone flap cannot be replaced for other reasons. This portion of the skull may be stored and replaced later.


Like with any surgical procedure, there are risks from a craniotomy. The risk of specific complications depends on the areas of the brain affected by the surgery: Risks include:

  • Bleeding
  • Infection
  • Blood clots
  • Risks related to anesthesia
  • Retention of fluid
  • Swelling of the brain
  • Unintentional damage to the brain tissues and nerves, causing a loss of brain function


After your craniotomy, it’s important to follow the guidelines given to you by your doctor, including taking all prescribed medications for pain, swelling and/or seizure. Take care of the incision site. Sutures or stables are typically removed 7 to 10 days after surgery. 

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