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Extratemporal Cortical Resection
The largest part of the brain, the cerebrum, is divided into four paired
sections, called lobes--the frontal, parietal, occipital and temporal lobes.
Each lobe controls a specific group of activities. With temporal lobe epilepsy,
which is the most common type of epilepsy in teens and adults, the area where
the seizures start--called the seizure focus--is located within the temporal
lobe. However, seizures can start in any portion of the cerebral cortex, the
outer layer (gray matter) of the cerebrum.
What is an extratemporal cortical resection?
An extratemporal cortical resection is an operation to resect, or cut away,
brain tissue that contains a seizure focus. Extratemporal means the tissue is
located in an area of the brain other than the temporal lobe. The frontal lobe
is the most common extratemporal site for seizures. In some cases, tissue may be
removed from more than one area/lobe of the brain.
Who is a candidate for extratemporal cortical resection?
Extratemporal cortical resection may be an option for people with epilepsy
whose seizures are disabling and/or not controlled by medications, or when the
side effects of the medication are severe and significantly affect the person's
quality of life. In addition, it must be possible to remove the brain tissue
that contains the seizure focus without causing damage to areas of the brain
responsible for vital functions, such as movement, sensation, language and
memory.
What happens before surgery?
Candidates for extratemporal cortical resection undergo an extensive
pre-surgery evaluation including video electroencephalographic (EEG) seizure
monitoring, magnetic resonance imaging (MRI) and positron emission tomography
(PET). Other tests include neuropsychological memory testing, WADA test (to
lateralize the side of language), ictal SPECT, and magnetic resonance
spectroscopy. These tests help to pinpoint the seizure focus and determine if
surgery is possible.
What happens during surgery?
An extratemporal cortical resection requires exposing an area of the brain
using a procedure called a craniotomy. (Crani refers to the skull and otomy
means "to cut into.") After the patient is put to sleep (general
anesthesia), the surgeon makes an incision (cut) in the scalp, removes a piece
of bone and pulls back a section of the dura, the tough membrane that covers the
brain. This creates a "window" in which the surgeon inserts special
instruments to remove brain tissue. Surgical microscopes are used to give the
surgeon a magnified view of the area of the brain involved. The surgeon utilizes
the information gathered during the pre-operative evaluation--as well as during
surgery--to define, or map out, the route to the correct area of the brain.
In some cases, a portion of the surgery is performed while the patient is
awake, using medication to keep the person relaxed and pain free. This is done
so that the patient can help the surgeon find and avoid areas in the brain
responsible for vital functions such as brain regions of language and motor
control. While the patient is awake, the doctor uses special probes to stimulate
various areas of the brain. At the same time, the patient may be asked to count,
identify pictures or perform other tasks. The surgeon can then identify the area
of the brain associated with each task.
After the brain tissue is removed, the dura and bone are fixed back into
place, and the scalp is closed using stitches or staples.
What happens after surgery?
The patient generally stays in the hospital for 2 to 4 days. Most people
having extratemporal cortical resection will be able to return to their normal
activities, including work or school, in 4 to 6 weeks after surgery. The hair
over the incision will grow back and hide the surgical scar. Most patients will
need to continue taking anti-seizure medication for two or more years after
surgery. Once seizure control is established, medications may be reduced or
eliminated.
How effective is extratemporal cortical resection?
Extratemporal cortical resection is successful in eliminating or
dramatically reducing seizures in 45-65% of cases. Surgery generally is more
effective if only one area of the brain is involved.
What are the side effects of extratemporal cortical resection?
The following symptoms may occur after surgery, although they generally go
away on their own:
- Scalp numbness
- Headaches
- Nausea
- Difficulty speaking, remembering things or finding words
- Feeling tired or depressed
What are the risks of extratemporal cortical resection?
The risks associated with extratemporal cortical resection are rare and
mainly depend on which area of the brain is involved. They may include:
- Risks associated with surgery, including infection, bleeding and allergic
reaction to anesthesia
- Swelling of the brain
- Failure to relieve seizures
- Changes in personality or behavior
- Partial loss of vision, memory or speech
- Stroke
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