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. The temporal lobe is the most common ''seizure focus,'' the area where most seizures start, in teens and adults.
However, epileptic seizures can be ''extratemporal,'' or outside of the temporal lobe, originating in the frontal, parietal or occipital lobes, or even more than one lobe. If this is the case, extratemporal cortical resection surgery may be warranted in some cases.
A seizure occurs when there’s abnormal electrical activity in the brain. Seizures may go virtually unnoticed. Or, in severe cases, they may produce a change or loss of consciousness and involuntary muscle spasms called convulsions. Seizures usually come on suddenly and vary in duration and severity. A seizure may be a one-time event, or you may have seizures repeatedly. Recurrent seizures are called epilepsy, or a seizure disorder. Less than one in 10 people who has a seizure develops 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, the Wada test (to determine which side of the brain controls language function), 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.