Surgery for Brain Tumors in Children

Surgery is part of the treatment for many people with tumors of the brain or spinal cord. For some types of brain tumors, the amount of tumor that can be removed has a major impact on outlook. For others, complete removal of the tumor is not necessary for a good outlook, because other treatments work well. Balancing the benefits of surgery with the risk of causing damage to important parts of the brain is one of the most important things your cancer care team will consider.

How is surgery used for brain tumors?

For people with brain tumors, surgery may be done to:

• Get a biopsy sample to determine the type of tumor and whether the tumor cells have certain gene changes that might affect treatment and prognosis (outlook)
• Remove the tumor or as much of it as possible
• Help prevent or treat symptoms or possible complications from the tumor

Before surgery, be sure you understand the goal of the surgery, as well as its potential benefits and risks.

Craniotomy to remove the tumor

Most often, the first step in treatment is for the neurosurgeon to remove as much of the tumor as is safe without affecting normal brain function. This is known as a maximal safe resection. It is most often done with a craniotomy, a surgical opening made in the skull.

Which types of brain tumors can be removed?

For some types of tumors the surgeon may be able to remove the entire tumor, but for other types this is not the case.

Surgery alone or combined with chemotherapy, targeted therapy, or radiation therapy may control or cure many slower-growing tumors, including:

• Some low-grade astrocytomas
• Dysembryoplastic neuroepithelial tumors (DNETs)
• Ependymomas
• Craniopharyngiomas
• Gangliogliomas
• Meningiomas

Tumors that tend to grow into nearby brain tissue, such as anaplastic astrocytomas or glioblastomas, cannot be cured by surgery alone. Surgery can sometimes reduce the amount of tumor that needs to be treated with radiation or chemotherapy, which might improve the results of these treatments.

Surgery can be done to relieve some of the symptoms caused by brain tumors, particularly those caused by increased pressure within the skull, such as headaches, nausea, vomiting, and blurred vision. Surgery can be used to remove tumors that are pressing on the spinal cord and other important parts of the nervous system. It may also make seizures easier to control with medicines.

Surgery may not be a good option in some cases, such as if the tumor is deep within the brain or if it has spread to a part of the brain that cannot be removed, such as the brain stem. If this is the case, other treatments may be used instead.

How is a craniotomy done?

A craniotomy may be done under general anesthesia (in a deep sleep) or while the person is awake (with the surgical area numbed) if brain function needs to be assessed during the operation.

Opening the skull

Part of the head might need to be shaved before surgery. The neurosurgeon makes an incision (cut) in the scalp and folds back the skin. A special drill is used to remove the piece of skull over the tumor. The opening is typically large enough for the surgeon to insert several instruments and view the parts of the brain needed to operate safely.

Locating the tumor

Many devices can help the surgeon see the tumor and surrounding brain tissue. The surgeon often operates while looking at the brain through a microscope. MRI or CT scans can be done before surgery to help locate tumors deep in the brain, or ultrasound can be used once the skull has been opened.

Avoiding vital parts of the brain

The surgeon can use different techniques to lower the risk of removing or damaging vital parts of the brain, such as:

• Functional MRIs, magnetic resonance spectroscopy (MRS), and diffusion tensor imaging (DTI): These imaging tests can be done before surgery to locate important parts of the brain and help the surgeon avoid them during the operation.
• Intraoperative cortical stimulation (cortical mapping): The surgeon can electrically stimulate different areas of the brain during surgery and monitor the response. This can show whether these areas control an important function and should be avoided.
• Intraoperative MRI: MRI can be done during surgery to find any left-over tumor before finishing the procedure. This may allow some brain tumors to be removed more safely and completely.
• Fluorescence-guided surgery: For some types of tumors, such as glioblastomas, the child may be given a special dye through their IV line. The dye is taken up by the tumor, which then glows under fluorescent light. This can help the surgeon tell the difference between the tumor and normal brain tissue.

Removing the tumor

The surgeon will remove as much of the tumor as is safe. This can be done in several ways depending on how hard or soft it is, and whether it has many or just a few blood vessels:

• Tumors may be cut out with a scalpel or special scissors.
• Some tumors are soft and can be removed with suction devices.
• In other cases, a handheld tool can be placed into the tumor to break it up and suction it out.

Closing the skull

After removing the tumor, the surgeon replaces the piece of skull bone and closes the incision. If any metal screws, wires, or plates are needed to fasten the bone, they are usually made from titanium. This allows the child to get follow-up MRIs and will not set off metal detectors.

Other surgical approaches

Depending on where the tumor is, other approaches might be used.

Neuroendoscopy: Tumors lower in the brain or near the base of the skull can sometimes be removed through the nose or mouth. This procedure is less invasive and may also be an option for certain types of tumors, such as those near the pituitary or pineal gland.

Stereotactic needle biopsy: In some cases, when tumors are deep in parts of the brain difficult to access with surgery, doctors can guide a needle into the tumor to collect a small sample. This procedure is called a stereotactic needle biopsy, and it can be used to learn more about a tumor. This can be helpful for tumors deep in the brain, such as diffuse intrinsic pontine glioma (DIPG), which are diagnosed based on imaging tests. Even when surgery to remove the tumor would be too risky, a small tissue sample can be tested for certain genes, which may be useful in finding targeted therapies or clinical trials.

What to expect after surgery

After the operation to remove the tumor, the child may have a tube (called a drain) coming out of the incision to allow excess cerebrospinal fluid (CSF) to drain from the skull. Other tubes may be placed to allow blood that builds up after surgery to drain from under the scalp. The drains are usually removed after a few days.

An imaging test, such as an MRI or CT scan, is typically done 1 to 3 days after the operation to confirm how much of the tumor has been removed.

Recovery time in the hospital is usually a few days to a week, but this depends on the size and location of the tumor, the child’s health, and whether other treatments are given. Healing around the surgery site usually takes several weeks.

Laser interstitial thermal therapy (LITT)

For tumors that are hard to treat surgically, another option might be laser interstitial thermal therapy (LITT), also called stereotactic laser ablation (SLA). In this approach, the surgeon inserts a thin probe with a tiny laser on the end through a small hole in the skull and into the tumor. The laser is then used to heat and destroy (ablate) the tumor. This technique is still fairly new, so doctors are still learning about the best ways to use it.

Surgery to help with cerebrospinal fluid (CSF) flow blockage

If the tumor blocks the flow of CSF within the head, it can cause increased intracranial pressure (ICP) inside the skull. This can cause symptoms such as headaches, nausea, vomiting, seizures, blurred vision, and may even damage the brain and be life-threatening.

Removing the tumor can often help with this, but there are also other ways to drain extra CSF and lower the pressure if needed.

Shunt placement

To help relieve pressure caused by a buildup of CSF, the neurosurgeon may put in a tube called a shunt. One end of the shunt is placed in a ventricle of the brain (an area filled with CSF). The tube is then tunneled under the skin of the neck and chest, with the other end draining into the abdomen (a ventriculoperitoneal shunt or VP shunt) or, less often, the heart (a ventriculoatrial shunt or VA shunt). A one-way valve along the tubing helps control the flow of CSF.

A shunt may be placed before or after surgery to remove the tumor. Most children will need to stay in the hospital for about 1 to 3 days after the surgery. As with any operation, complications such as bleeding or infection may develop.

Shunts can be temporary or permanent. Sometimes they can break or become clogged and need to be replaced.

Endoscopic third ventriculostomy (ETV)

Another option to treat increased pressure in the skull in some cases is an endoscopic third ventriculostomy (ETV). In this operation, the surgeon makes an opening in the bottom of the third ventricle (a space filled with CSF) at the base of the brain to allow the fluid to flow again. This operation is done through a small hole in the front of the skull. An advantage of this approach is that it does not require a shunt, but there is a chance that the opening made in the ventricle might close up again over time.

Placing an external ventricular drain (EVD)

If the pressure inside the head needs to be relieved for a short time, an EVD might be put in place to allow excess CSF to drain out of the body. The drain is a small tube. One end is put into a ventricle, and the other end is attached to a collection bag outside the body. Along with collecting extra CSF, the drain can also be used to measure the pressure inside the skull, as well as to look for tumor cells, blood, or signs of infection.

The drain can be placed either during surgery or with a procedure done at the bedside in the hospital. It can be put in place to relieve the pressure in the days before surgery, or to help drain the fluid that collects after an operation.

If the pressure inside the skull needs to be lowered for more than a few days, the doctor might need to change this to a VP shunt.

Surgery to place a ventricular access catheter

In some cases, surgery may be done to insert an Ommaya reservoir or other ventricular access catheter under the scalp. This device can be used to give chemotherapy or remove CSF from the ventricles, if needed.

To place the reservoir, a small incision is made in the scalp, and a small hole is drilled in the skull. A flexible tube is then put through the hole until the open end is in a ventricle, where it reaches the CSF. The other end, which has a dome-shaped reservoir, stays just under the scalp.

Once the device is placed and healed, the hair over the area will regrow and it is often not visible. The device does not cause any pain.

Possible risks and side effects of surgery

Surgery on the brain or spinal cord is a serious operation, and surgeons are very careful to try to limit any problems either during or after surgery. Complications during or after surgery such as bleeding, infections, seizures, or reactions to anesthesia are uncommon, but they can happen.