Normal electrical impulses in the brain move in a vertical direction, while seizure activity spreads in a horizontal direction.
Multiple subpial transection involves cutting the horizontal nerves in the upper layers of the epileptogenic area of the brain
to prevent the spread of seizures, while leaving the vertical connections intact.
Multiple subpial transection may be done alone or with a resection (removal of a portion of the brain).
Indications
Multiple subpial transection is considered when:
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Seizures have persisted, despite trying medication (monotherapy and polytherapy) for at least two years.
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Pre-surgical evaluation shows multiple epileptogenic regions, or a single epileptogenic region that overlaps with vital speech
and memory areas of the brain.
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It is not possible to remove the epileptogenic area without affecting the critical functional areas of the brain.
Multiple subpial transection is sometimes used as a treatment for children with Landau-Kleffner syndrome. However, this use
of multiple subpial transection is controversial and a beneficial outcome for this procedure is not well established.
Before surgery
A complete and comprehensive pre-surgical evaluation is essential to locate the exact area of the brain to be operated on.
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 prior to the operation.
They will also discuss post-operative symptoms, any intensive care and rehabilitation that will be required, and possible
on-going deficits and care.
Anaesthetic
General and local anaesthesia is required. The anaesthetist will discuss the risks concerned and preparations required with
you. General anaesthesia requires several hours of fasting.
Surgery
The operation will take about six hours. Your child will be put to sleep under general anaesthesia. A portion of his head
will be shaved. Part of the scalp and bone will be removed and the dura membrane will be peeled back to expose the region
of the brain to be disconnected.
During the operation, intraoperative monitoring with intracranial EEG may be done to help the surgeon finely locate and disconnect
those and only those portions of the brain causing the seizures. The surgeon will also use a surgical microscope to get a
magnified view of the brain and make a series of parallel, shallow cuts in the epileptogenic area.
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 he comes 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 affected. Temporary side effects of this surgery,
which should disappear on their own in a few weeks, 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 he may have. In
the hospital, physical and occupational therapists will help your child and may show you some exercises. He may also need
speech therapy if his speech has been affected.
Once your child is at home, he may need to continue using the services of a physical or occupational therapist in the community.
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 should occur after the operation, further careful evaluation (using tests and scans) and possible re-surgery may
be required.
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 (peaking on the fourth day after
the operation), and allergy to or complications from anaesthetic.
Your child's doctor will discuss the risks of this procedure with you in detail.
