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?
In epilepsy, 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 an Extratemporal Cortical Resection?
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 an Extratemporal Cortical Resection?
An extratemporal cortical resection requires exposing an area of the brain using a procedure called a craniotomy. After the patient is put to sleep (general anesthesia), the surgeon makes an incision 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.