The largest part of the brain, the cerebrum, is divided into two hemispheres. Each hemisphere is divided into four lobes: the frontal lobe, the parietal lobe, the occipital lobe, and the temporal lobe.
Extratemporal resection involves surgically removing a portion of the brain outside the region of the temporal lobes. Seizures originating in areas outside the temporal lobes are grouped together under the term neocortical epilepsy. A common extratemporal area of seizure focus is the frontal lobe.
Indications
Extratemporal resection is considered when:
- seizures have persisted, despite trying medication (monotherapy and polytherapy) for at least two years
- the pre-surgical evaluation shows the seizures to originate outside the temporal lobes
- one or more lesions are visible on the MRI images (surgery may still be done if no lesion is visible, but there is less chance that the child will be seizure-free after surgery)
- video/scalp EEG recordings confirm that the seizures are arising from one brain region
- it is possible to remove the epileptogenic area without affecting the critical functional areas of the brain.
Before surgery
A complete and comprehensive pre-surgical evaluation is essential to locate the exact section or sections to be removed.
The surgeon and the team will explain the surgery to you and discuss all related issues. They will instruct you on any specific steps to take before the operation.
They will also discuss post-operative symptoms, any intensive care and rehabilitation that your child will need and possible ongoing deficits and care.
Surgery and invasive monitoring
Because extratemporal resection often involves areas of the brain that are near the areas that control movement, invasive monitoring may be required. If so, then your child will need two operations: one to implant the intracranial electrode grid, and a second a few days later to remove the grid. If the treatment team has recommended epilepsy surgery and you have agreed, the epileptogenic region of the brain will be removed during this second operation.
Grid implantation
Your child will be put to sleep under general anaesthestic. A portion of their head will be shaved. Part of the scalp and bone will be removed and the dura membrane will be peeled back. Preliminary intraoperative EEG monitoring may be done to help provide information about important areas of brain function.
After the placement of the intracranial electrode grid for invasive monitoring, the bone will be replaced and the scalp will be sutured closed. Your child will spend a few hours in the recovery room until they come out of anaesthesia. They will probably spend one night in the intensive care unit.
Invasive monitoring
Your child will be monitored in the intensive care unit or in a special video/EEG monitoring room with extra nursing care. The child will stay in this special hospital room while their brain activity is continuously monitored on the EEG and their activities are recorded on video. Their brain may also be stimulated with mild electrical impulses via the electrodes to localize areas controlling speech, movement and sensation. All this should give an accurate assessment of seizures, epileptogenic regions of the brain and other vital information.
By combining the information from the seizure monitoring and the functional mapping, the team can create a brain map that shows where the seizures are coming from and where important function is located in the brain. In this way, the team can tell which "parts" of the brain contributing to the seizures can be safely removed. All of this information will be presented to you and your child as well as the team's recommendation for a surgical strategy.
Grid removal and epilepsy surgery
When the doctors have enough information about the origin of the seizures, they will be able to accurately plan their treatment approach. They may recommend proceeding with epilepsy surgery. If you agree that this is in the best interests of your child, a second operation is done to remove or disconnect the epileptogenic area of the brain and at the same time remove the intracranial electrodes. If you or the team do not wish to proceed with epilepsy surgery, an operation is done only to remove the electrodes.
Your child will be returned to the operating room and the grid will be removed. If you and the team have decided to go ahead with epilepsy surgery, the epileptogenic area of the brain will also then be removed. After the epileptogenic area has been removed, further intracranial EEG recordings may be done to determine whether more brain tissue needs to be removed or if the whole epileptogenic area was removed. The electrodes that are used in this procedure are removed at the end of the operation.
After the operation, the bone will be replaced and the scalp will be sutured closed. Your child will spend a few hours in the recovery room until they come out of anaesthesia and one or two days in the intensive care unit, followed by about a week at the hospital.
After surgery
Side effects of the surgery depend on the specific areas of the brain that are removed. Temporary side effects of this surgery, which should disappear on their own in a few days, are scalp numbness, nausea, fatigue, depression, headaches, difficulties with memory and speech and auras (feelings that signal the start of a seizure). Rarely, some of these effects may persist. The surgeon and neurologist can talk with you about the side effects they expect for your child.
Your child may benefit from doing exercise therapy to improve any physical weakness or loss of coordination they may have. In the hospital, physical and occupational therapists will help your child and may show you some exercises. They may also need speech therapy if their speech has been affected.
Once your child is at home, they may need to continue using the services of a physical or occupational therapist in the community. Alternatively, they may be given some exercises to do on their own. The treatment team will discuss this with you and may be able to help you find a therapist.
The hair should grow back and most children are able to return to normal activities and school two or three months after surgery.
Anti-epileptic drugs should be continued after the surgery. As always, any change in dosage should be made under advice and monitoring of your child's doctor. Sometimes the drugs can be stopped after a few seizure-free years. However, even in children made completely seizure-free by the surgery, the anti-epileptic drugs usually should be continued for at least two years.
If seizures occur after the operation, your child may need further careful evaluation (using tests and scans) and possible further surgery.
What can you expect from the surgery?
Every child is different. Depending on the nature of your child's seizures and the location of the epileptogenic region, surgery may result in complete seizure control or partial
seizure control with less need for medication. There may also be some chance that the surgery will not improve things. Talk to your child's doctor about what you and your child can realistically expect as a result of the surgery.
Complications and risks
Every surgical procedure has related risks, including infection, bleeding, cerebral edema, and allergy to or complications from anaesthetic. Your child's doctor will discuss the risks of this procedure with you in detail.