What is it?
A craniotomy is any operation where a surgeon makes an opening in the skull, or cranium, in order to gain access to the brain.
What is its goal?
The goal of a craniotomy for a patient with a brain tumor is to obtain abnormal tissue for examination under a microscope and to remove as much of a tumor as is safe.
How is it done?
Most craniotomies for brain tumor removal are done using a procedure called “image guidance.” Image guided craniotomies are a special type of stereotactic, or 3-dimensional neurosurgery. As part of the preparation for the surgery, patients receive a special MRI or CT scan within 3-days of their planned surgery. This scan is used in conjunction with a special 3-dimensional neuronavigation system. The system allows surgeons to watch on a computer screen while performing surgery to determine if their instruments are on target, near critical structures of the brain that need to be preserved, and to know when all of the tumor has been removed.
Additional measures are used during the surgery to help the surgeon ensure normal brain tissue is not being injured. Neurophysiologic monitoring uses a set of electrical signals delivered throughout the surgery to ensure that impulses are being carried to the brain normally and not being interrupted by the planned tumor resection. Functional MRI scans can be obtained preoperatively and merged with the neuronavigation scans so surgeons can see the relationship between critical brain tissue and tumor. Lastly, craniotomies can be performed with the patient awake. Operating with the patient conscious helps the surgeon test areas of the brain surrounding the tumor to be sure that speech is not affected by the planned surgery.
Once the route to the tumor has been mapped and determined to be safe by the surgeon, an incision overlying the tumor is made. The surgeon makes an opening in the skull using a high speed drill that safely cuts into the skull, without injuring the underlying brain. Once the opening in the skull is made, the surgeon makes a small incision in the “Dura mater” a membrane covering the brain. A certain type of tumor known as a meningioma actually arises from this layer and in such cases, the surgeon may make a cut in the dura around the tumor so that the tumor can be removed with its layers of attachment.
Once the dura is open, the surgeon uses visual landmarks and the neuronavigation system to identify the tumor. He then takes a small biopsy of the tumor that is reviewed with the neuropathologist. If the biopsy confirms the presence of the tumor, the surgeon proceeds with removal.
A variety of tools are used to remove the tumor. These are designed to dissect the tumor free of the surrounding normal brain tissue. Depending on the tumor type, it may be removed as a single tumor or broken down into smaller pieces. In many cases, an ultrasonic aspirator is used. The ultrasonic aspirator vibrates the tumor apart and then aspirates the broken up pieces of tumor without injuring normal blood vessels.
At the end of the surgery, the surgeon closes the dura, either with sutures or a graft, and then replaces the bony opening in the skull. This is reattached with small titanium screws and plates that are left in place permanently. The skull gradually heals back solid over time like any other bone. The scalp is usually closed with a combination of sutures and staples.
What is the success rate?
The success rate for obtaining a complete tumor resection depends on the type of tumor being treated and its location. While complete tumor removal is usually desirable, if the tumor is too extensive or is too deep, it is more important not to injure normal brain tissue than it is to excise the tumor from excessively risky territory.
What are the risks?
In the vast majority of cases, tumor surgery is safe and effective. At the University of Rochester our elective surgery mortality rate is <1% which is in line with the best university brain tumor centers in the country. The most common risks requiring re-admission to the hospital are infection (2%), deep venous thrombosis (3%), and seizures (3%). Neurological impairment following surgery is also relatively rare (4%) and when it occurs is usually temporary. Risks are higher when surgery has to be performed in an emergency setting.
How long will I be in the hospital?
Our average length of stay following craniotomy is 2.2 days. Most patients are able to go directly home following surgery (96% for elective surgery) and 4% have to go to a rehab hospital. The most significant factor in determining who will be able to go home following surgery is how the patient was doing prior to surgery. While surgery may improve symptoms such as weakness, speech difficulties, and memory, such improvements usually take several weeks. If a patient has significant pre-operative problems those problems will also be present immediately post-op (even if they eventually disappear).
How long does it take to get the results of the tumor?
The surgeons and pathologists will take a quick look at the biopsy specimen at the time of surgery using a process known as a frozen section. This quick look allows the surgeon and pathologist to be sure that the biopsy specimen is abnormal, but is not sufficient to completely diagnose the problem. The final sections which are chemically process and stained portions of the specimen that are used to determine the final diagnosis take 48-72 hours to process and examine.
What happens next?
After surgery, treatment will depend on the type of tumor encountered. Additional treatment may consist of radiation therapy, stereotactic radiosurgery, chemotherapy, or nothing. If additional therapy is necessary it will start 2-3 weeks following your operation. We need this pause to allow your body to heal from the surgery prior to starting any additional treatments.
Patient Outcomes
- In 2007, a total of 213 craniotomies for tumor resection were performed at Strong Memorial Hospital.
- Inpatient mortality was 0.9% (2 patients). Both of these patients required urgent surgery and were admitted through the emergency department.
- The mortality rate for planned craniotomy surgery was 0%.
- The average length of stay for patients undergoing planned surgery for brain tumor removal was 2.65 days in the hospital and 96% were able to go directly home following their stay in the hospital, while 4% were admitted to a rehabilitation facility.
- The rate of infection requiring hospital readmission was 1.4% (3 patients) and the rate of severe deep venous thrombosis was 0.9% (2 patients).