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Surgery for childhood brain and spinal cord tumours
Surgery is the main treatment for childhood brain and spinal cord tumours. Surgery is commonly the first treatment used. Surgery alone or combined with radiation therapy can be used to control or treat many tumours. Some tumours may not be treated with surgery alone, but surgery can reduce the amount of tumour that needs to be treated by radiation or chemotherapy and can also improve the results of these treatments.
Surgery may be done for different reasons. Your child may have surgery to:
- potentially cure the cancer by completely removing the tumour
- remove as much of the tumour as possible before using other therapies
- remove a sample of the tumour to confirm the diagnosis of cancer (a biopsy)
- relieve symptoms related to the tumour (called palliative surgery)
- insert a plastic tube (shunt) to drain cerebrospinal fluid (CSF) to relieve pressure on the brain
- place a special dome-shaped device (Ommaya reservoir) to remove CSF or give chemotherapy
The type of surgery used will depend on the size and location of the tumour, the type of tumour and the child’s age. Some areas of the brain and spinal cord are difficult to reach or have functions that are too important to be damaged by an attempt to surgically remove the tumour. Tumours that cannot be removed are called inoperable or unresectable.
A child with a brain or spinal cord tumour is evaluated very carefully before surgery. A neurological exam will be done to look for any changes to normal functions, such as reflexes, speech, hearing, vision, thinking, movement, feeling and body functions.
Treatment for swelling or seizures may also be necessary before surgery. Doctors may give corticosteroids before surgery to reduce the swelling, relieve symptoms and improve neurological function. Doctors may give antiseizure or anti-epileptic medicines before surgery to control seizure activity.
The location of the tumour is carefully mapped out before surgery using a CT scan or an MRI. This will help the surgeon decide if the tumour can be removed with surgery. A functional MRI may be used to help plan surgery. This helps the surgeon know which areas are important to avoid. It involves asking the child to answer questions or move certain parts of the body while scans are being done.
A craniotomy is the most common type of surgery used to treat brain and spinal cord tumours. It is surgery that opens the skull to remove a brain tumour. The goal of the surgery is to remove as much of the tumour as possible without destroying important brain tissue or affecting brain functions. Image-guided surgery may be used for some brain tumours. This involves taking images with an MRI or a CT scan during the operation to show the location of the tumour and the surgeon’s instruments.
A craniotomy may be done under general anesthesia, but your child may be awake for at least part of the surgery. If the doctor needs to assess brain function (called brain mapping) then your child will need to be awake.
During the surgery, a cut (incision) is made in the scalp. A piece of the skull is removed to expose the area where the brain tumour is growing. This piece of skull is often called the bone flap. The surgeon then makes a cut in the covering of the brain (dura mater) and pulls it apart slightly to find and reach the tumour. The surgeon removes as much of the tumour as possible.
A special ultrasound machine is sometimes used to break up the tumour and make it easier to remove. The surgeon may also use a special operating microscope that helps to identify the edges of the tumour.
Once the surgeon has removed as much of the tumour as possible, the dura mater is tightly stitched together, the piece of skull is replaced with small screws and plates and the scalp is closed with stitches or staples. If the brain is very swollen after surgery, the piece of skull may be replaced later when the swelling has gone down. Healing usually takes several weeks.
Brain mapping is done during a craniotomy when a tumour is near areas of the brain that control speech or motor function. Mapping is done using a technique called intraoperative cortical stimulation. It involves stimulating the surface of the brain with a mild electrical current to determine the function of a particular part of the brain. The procedure is painless. It produces temporary speech disturbance or twitching in the part of the body that is controlled by the area of the brain being stimulated. This information is then “mapped” so that the surgeon can avoid these areas when removing the tumour.
Speech mapping tracks the areas around the tumour that are responsible for speech and understanding speech. After a general anesthetic is given, the surgeon opens the skull and dura mater to expose the brain. The child is then woken up so that they can talk to the surgeon and follow any instructions given during the mapping, such as repeating words or counting. When the mapping is finished, the child is given a general anesthetic again and the surgeon continues the operation to remove the tumour.
Motor mapping tracks the areas around the tumour that are responsible for movement and reflexes. The child may remain under general anesthetic if the surgeon does not need direct feedback from the child. The surgeon stimulates the areas around the tumour with an electrical current and watches for any movement of the body. As with speech mapping, the surgeon uses the mapped areas as a guide when removing the brain tumour.
Transsphenoidal means the surgeon goes through the sphenoid sinus to access the tumour. Transsphenoidal surgery may be used to remove some types of brain tumours that are located near the pituitary gland. It is usually only possible for smaller tumours. Larger tumours often need to be removed with a craniotomy.
Transsphenoidal surgery is done under general anesthetic. The child’s head will be placed in a headrest to keep it still during surgery. The surgeon makes a cut under the upper lip along the gum line or at the bottom of the nose between the nostrils. The surgeon then cuts through the sphenoid bone to reach the area around the pituitary gland. The surgeon removes as much of the tumour as possible using special instruments. The cut is closed and the nostrils are packed with gauze or a special nasal sponge.
The nostrils will be packed for a few days so your child will need to breathe through their mouth.
Surgery to treat cerebrospinal fluid (CSF) buildup
Brain tumours can cause a buildup of CSF in the brain that can cause increased pressure in the skull. This is called intracranial pressure (ICP) or hydrocephalus. It occurs when the tumour blocks the flow of CSF and causes it to build up leading to an increase in intracranial pressure. This can cause headaches, vomiting, irritability and seizures. In infants, it can also cause a bulging soft spot on the head. Surgery to remove the tumour can help with this, but there are also other ways to drain away excess CSF and lower pressure in the skull.
External ventricular drain
An external ventricular drain (EVD) is a thin tube inserted through the skin and skull into a fluid-filled chamber (ventricle) in the brain (called a ventriculostomy). It allows CSF to drain from the brain into a collection system or bag outside the body. An EVD is sometimes used to treat a buildup of CSF before or during surgery to remove a brain tumour. The EVD can’t be left in place permanently. It is typically removed when it is no longer needed, or it is replaced with a shunt if drainage is still needed.
A shunt is a narrow, soft, flexible piece of tubing. It has a valve system that regulates the pressure of the CSF and prevents fluid from flowing back into the ventricles. Many shunts have reservoirs that may be used to remove CSF samples. A shunt may be needed if the brain tumour is blocking the flow of CSF and causing fluid buildup in the brain (hydrocephalus).
During surgery, the shunt is placed in a ventricle of the brain that is filled with CSF. It leads from the ventricle to the scalp. From there, it runs under the skin of the neck and chest and into the abdominal cavity (not the stomach). The CSF that drains into the abdominal cavity is reabsorbed into the bloodstream. A shunt may be temporary or permanent.
An endoscopic third ventriculostomy (ETV) is a procedure in which the surgeon makes an opening and places a tube in the third ventricle of the brain to allow CSF to flow around an obstruction. The surgeon uses an endoscope to navigate within the ventricle and create an internal bypass. ETV is sometimes used to treat a buildup of CSF in the brain. It can also be used to biopsy or remove tumours within the ventricles of the brain.
An Ommaya reservoir is a small, dome-shaped device with a short tube (catheter) attached to it. The surgeon inserts the reservoir under the scalp, and the catheter is threaded into a ventricle or cyst in the brain.
The reservoir may be used to:
- get samples of CSF
- inject drugs, such as chemotherapy, directly into the CSF
- inject chemotherapy drugs directly into a tumour or cyst
- remove extra CSF to relieve pressure
Side effects can happen with any type of treatment for childhood brain and spinal cord tumours, but everyone’s experience is different. Some children have many side effects. Other children have only a few side effects.
If your child develops side effects, they can happen any time during, immediately after or a few days or weeks after surgery. Sometimes late side effects develop months or years after surgery. Most side effects will go away on their own or can be treated, but some may last a long time or become permanent.
Side effects of surgery will depend mainly on the type of surgery, the size and location of the tumour and your child’s age and overall health. Surgery for childhood brain and spinal cord tumours may cause these side effects:
- swelling around the cut (incision)
- posterior fossa syndrome
- CSF buildup and leakage
- jaw pain
- blood clots
- vision problems
- hormone problems
- behaviour or personality changes
Side effects, such as swelling, may sometimes get worse after surgery.
Tell the healthcare team if your child has these side effects or others you think might be from surgery. The sooner you tell them of any problems, the sooner they can suggest ways to help your child.