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Procedure overview

What is a craniotomy?

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

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 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.

Scans made of the brain, in conjunction with these computers and localizing frames, provide a three-dimensional image, for example, of a tumor within the brain. It is useful in making the distinction between tumor tissue and healthy tissue and reaching the precise location of the abnormal tissue.

Other uses include stereotactic biopsy of the brain (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 another 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 which 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 the aneurysm. Placement of a metal clip across the "neck" of the aneurysm isolates the aneurysm from the rest of the circulatory system by blocking blood flow, thereby preventing rupture.

Craniectomy is a similar procedure that involves the permanent 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.

Other related procedures that may be used to diagnose brain disorders include cerebral arteriogram, computed tomography (CT) scan of the brain, electroencephalogram (EEG), magnetic resonance imaging (MRI) of the brain, positron emission tomography (PET) scan, and X-rays of the skull. Please see these procedures for additional information.

Anatomy of the brain

The brain and spinal cord make up the central nervous system (CNS). The CNS controls all the functions of the body such as vision, taste, touch, muscle movement, breathing, thought, behavior, memory, and emotion. Every process in the body is affected by the brain.

What are the different sections of the brain?

Anatomy of the?brain, adult
Click Image to Enlarge

The brain has three main sections, the cerebrum, brainstem, and cerebellum. Each section has unique functions:

  • Cerebrum. The cerebrum (forebrain or front brain) is the largest section of the brain. It is composed of right and left hemispheres, which control the opposite sides of the body. For example, the left side of the brain controls the right side of the body, along with speech. Functions of the cerebrum include initiation and coordination of movement, sensation, touch, vision, hearing, speech and language, judgment, reasoning, problem solving, emotions, learning, and control of body temperature.

  • Brainstem. The brainstem (mid brain) includes three divisions: midbrain, pons, and medulla. Here information is relayed between the peripheral nerves and spinal cord to the upper parts of the brain

    Some specific functions of the brainstem include:

    • Control of vital signs, such as breathing, heart rate, and blood pressure

    • Alertness

    • Sleepiness

    • Eye movement

    • Involuntary muscle movements such as sneezing, coughing, vomiting, yawning, and swallowing

    • Facial movement

    • Sensation on the face and parts of the scalp

    • Balance

    • Some aspects of hearing

  • Cerebellum. The cerebellum (back brain) is located in the back of the skull. Its function is to coordinate voluntary muscle movements and to maintain posture and balance.

The three main regions of the brain are broken down into more specific areas which include the following:

  • Pons. A deep part of the brain, located in the brainstem, the pons contains many of the control areas for eye and face movements.

  • Medulla. The lowest part of the brainstem, the medulla is the most vital part of the entire brain and contains important control centers for the heart and lungs.

  • Frontal lobe. The frontal lobe, the largest section of the brain, is located in the front of the head. It is involved in personality characteristics, judgment, decision-making, behavior, movement, and speech.

  • Parietal lobe. The middle part of the cerebrum, the parietal lobe helps a person to identify objects and understand spatial relationships. The parietal lobe is also involved in localizing and interpreting pain and touch in the body. It is also responsible for interpreting verbal input or understanding speech.

  • Occipital lobe. The occipital lobe is the back part of the cerebrum. It is involved with vision.

  • Temporal lobe. The sides of the cerebrum, the temporal lobes are involved in memory, speech, and sense of smell.

  • Spinal cord. The spinal cord is a large bundle of nerve fibers extending from the base of the brain to the lower back. The spinal cord carries messages to and from the brain and the rest of the body.

Reasons for the procedure

A craniotomy may be performed for a variety of reasons, including, but not limited to, the following:

  • Diagnosing, removing, or treating brain tumors

  • Clipping or repairing of an aneurysm

  • Removing blood or blood clots from a leaking blood vessel

  • Removing an arteriovenous malformation (AVM). An abnormal mass of blood vessels (arteries and veins)

  • Draining a brain abscess. An infected pus-filled pocket

  • Repairing skull fractures

  • Repairing a tear in the membrane lining the brain (dura mater)

  • Relieving pressure within the brain (intracranial pressure) by removing damaged or swollen areas of the brain that may be caused by traumatic injury or stroke

  • Treating epilepsy. A neurological condition involving the brain that makes people more susceptible to seizures.

  • Implanting stimulator devices to treat movement disorders such as Parkinson's disease or dystonia (a type of movement disorder)

There may be other reasons for your doctor to recommend a craniotomy.

Risks of the procedure

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:

  • Infection

  • Hemorrhage (bleeding)

  • Thrombus (formation of blood clots)

  • Pneumonia (infection of the lungs)

  • Unstable blood pressure

  • Seizures

  • Muscle weakness

  • Brain swelling

  • Leakage of cerebrospinal fluid (the fluid that surrounds and cushions the brain)

  • Risks associated with the use of general anesthesia

The following additional complications are rare and generally relate to specific locations within the brain, so they may or may not be valid risks for certain individuals:

  • Memory problems

  • Speech difficulty

  • Paralysis

  • Abnormal balance or coordination

  • Coma

There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your doctor prior to the procedure.

Before the procedure

  • Your doctor will explain the procedure to you and offer you the opportunity to ask any questions that you might have about the procedure.

  • You will be asked to sign a consent form that gives permission to do the surgery. Read the form carefully and ask questions if something is not clear.

  • In addition to a complete medical history, your doctor will perform a physical examination to ensure you are in good health before you undergo the surgery. You may also need blood tests and other diagnostic tests.

  • You will receive a preoperative neurological examination that will be used to compare with postoperative examinations.

  • You will be asked to fast before the procedure, generally after midnight.

  • If you are pregnant or suspect that you are pregnant, you should notify your health care provider.

  • Notify your doctor if you are sensitive to or are allergic to any medications, latex, tape and anesthetic agents (local or general).

  • Notify your doctor of all medications (prescribed and over-the-counter) and herbal supplements that you are taking.

  • Notify your doctor if you have a history of bleeding disorders or if you are taking any anticoagulant (blood-thinning) medications, aspirin, or other medications that affect blood clotting. It may be necessary for you to stop these medications prior to the procedure.

  • If you smoke, you should stop smoking as soon as possible prior to the procedure, in order to improve your chances for a successful recovery from surgery and to improve your overall health status.

  • You may be asked to wash your hair with a special antiseptic shampoo the night before the surgery.

  • You may receive a sedative prior to the procedure to help you relax.

  • The areas around the surgical site will be shaved.

  • Based on your medical condition, your doctor may request other specific preparation.

During the procedure

A craniotomy generally requires a hospital stay of three to seven days. You may also go to a rehabilitation unit for several days after your hospital stay. Procedures may vary depending on your condition and your doctor's practices.

Illustration of an example of a craniotomy procedure
Click Image to Enlarge

Generally, a craniotomy follows this process:

  1. You will be asked to remove any clothing, jewelry, or other objects that may interfere with the procedure.

  2. You will be given a gown to wear.

  3. An intravenous (IV) line will be inserted in your arm or hand.

  4. A urinary catheter will be inserted to drain your urine.

  5. You will be positioned on the operating table in a manner that provides the best access to the side of the brain to be operated on.

  6. The anesthesiologist will continuously monitor your heart rate, blood pressure, breathing, and blood oxygen level during the surgery.

  7. Your head will be shaved and the skin over the surgical site will be cleansed with an antiseptic solution.

  8. There are various types of incisions that may be used, depending on the affected area of the brain. An incision may be made from behind the hairline in front of your ear and the nape of your neck, or in another location depending on the location of the problem. If an endoscope is used, the incisions may be smaller.

  9. The scalp will be pulled up and clipped to control bleeding while providing access to the brain.

  10. A medical drill may be used to make burr holes in the skull. A special saw may be used to carefully cut the bone.

  11. The bone flap will be removed and saved.

  12. The dura mater (the thick outer covering of the brain directly underneath the bone) will be separated from the bone and carefully cut open to expose the brain.

  13. Excess fluid will be allowed to flow out of the brain, if needed. Microsurgical instruments, such as a surgical microscope to magnify the area being treated, may be used. This can enable the surgeon a better view of the brain structures and distinguish between abnormal tissue and healthy tissue. Tissue samples may be sent to the lab for testing.

  14. A device, such as a drain or a special type of monitor, may be placed in the brain tissue to measure the pressure inside the skull, or intracranial pressure (ICP). ICP is pressure created by the brain tissue, cerebral spinal fluid (CSF), and blood supply inside the closed skull.

  15. Once the surgery is completed, the surgeon will suture (sew) the layers of tissue together.

  16. The bone flap will be reattached using plates, sutures, or wires.

  17. If a tumor or an infection is found in the bone, the flap may not be replaced. Also, if decompression (to reduce pressure in the brain) is required, the bone flap may not be replaced.

  18. The skin incision (scalp) will be closed with sutures or surgical staples.

  19. A sterile bandage or dressing will be applied over the incision.

After the procedure

In the hospital

Immediately after the procedure, you will be taken to a recovery room for observation before being taken to the intensive care unit (ICU) to be closely monitored. Alternately, you may be taken directly to the ICU from the operating room.

Your recovery process will vary depending upon the type of procedure performed and the type of anesthesia given. Once your blood pressure, pulse, and breathing are stable and you are alert, you may be taken to the ICU or your hospital room.

After staying in the ICU, you will move to a room on a neurosurgical nursing unit in the hospital. You will remain in the hospital for several more days.

You may need oxygen for a period of time after surgery. Generally, the oxygen will be discontinued before you go home.

You will be taught deep-breathing exercises to help re-expand the lungs and prevent pneumonia.

Frequent neurological checks will be performed by the nursing and medical staff to test your brain function and to make sure your body systems are functioning properly after your surgery. You will be asked to follow a variety of basic commands, such as moving your arms and legs, to assess your brain function. Your pupils will be checked with a flash light, and you will be asked questions to assess your orientation (such as your name, the date, and where you are). The strength of your arms and legs will also be tested.

The head of your bed may be elevated to prevent swelling of your face and head. Some swelling is normal.

You will be encouraged to move around as tolerated while in bed and to get out of bed and walk around, with assistance at first, as your strength improves. A physical therapist (PT) may be asked to evaluate your strength, balance, and mobility, and give you suggestions for exercises to do both in the hospital and at home.

You will likely have sequential compression devices (SCDs) placed on your legs while you are in bed to prevent blood clot formation. SCDs have an air compressor that slowly pumps air into and out of fitted sleeves that are placed on the legs. They help prevent blood clots from forming by passively compressing the leg veins to keep blood moving.

Depending on your situation, you may be given liquids to drink a few hours after surgery. Your diet may be gradually changed to include more solid foods as tolerated.

You may have a catheter in your bladder to drain your urine for a day or so, or until you are able to get out of bed and move around. Be sure to report any painful urination or other urinary symptoms that occur after the catheter is removed, as these may be signs of an infection that can be treated.

Depending on your status, you may be transferred to a rehabilitation facility for a period of time to regain your strength.

Before you are discharged from the hospital, arrangements will be made for a follow-up visit with your doctor. Your doctor will also give you instructions for home care.

At home

Once you are home, it is important to keep the incision clean and dry. Your doctor will give you specific bathing instructions. If stitches or surgical staples are used, they will be removed during a follow-up office visit. If adhesive strips are used, they should be kept dry and generally will fall off within a few days.

You may choose to wear a loose turban or hat over the incision. You should not wear a wig until the incision is completely healed (about 3 to 4 weeks after surgery).

The incision and head may ache, especially with deep breathing, coughing, and exertion. Take a pain reliever for soreness as recommended by your doctor. Aspirin or other blood thinning medications may increase the chance of bleeding. Be sure to take only recommended medications and ask if you are unsure.

You should continue the breathing exercises used in the hospital to prevent lung infection. You will be advised to avoid exposure to upper respiratory infections (colds and flu) and irritants, such as tobacco smoke, fumes, and environmental pollution.

You should gradually increase your physical activity as tolerated. It may take several weeks to return to your previous level of energy and strength.

You may be instructed to avoid lifting heavy items for several weeks in order to prevent strain on your surgical incision.

Do not drive until your doctor gives you permission.

Notify your doctor to report any of the following:

  • Fever and/or chills

  • Redness, swelling, or bleeding or other drainage from the incision site or face

  • Increased pain around the incision site

  • Vision changes

  • Confusion or excessive sleepiness

  • Weakness of your arms or legs

  • Speech difficulty

  • Difficulty breathing, chest pain, anxiety, or change in mental status

  • Green, yellow, or blood-tinged sputum (phlegm)

  • Seizure activity

Following a craniotomy, your doctor may give you additional or alternate instructions, depending on your particular situation.

Online resources

The content provided here is for informational purposes only, and was not designed to diagnose or treat a health problem or disease, or replace the professional medical advice you receive from your doctor. Please consult your health care provider with any questions or concerns you may have regarding your condition.

This page contains links to other websites with information about this procedure and related health conditions. We hope you find these sites helpful, but please remember we do not control or endorse the information presented on these websites, nor do these sites endorse the information contained here.

American Association of Neurological Surgeons

American Brain Tumor Association

American Neurological Association

American Stroke Association

National Brain Tumor Society

National Institute of Neurological Disorders and Stroke

National Institutes of Health (NIH)

National Library of Medicine

Pediatric Brain Tumor Foundation