Epilepsy and Temporal Lobe Resection
The largest part of the brain, the cerebrum, is divided into four paired sections -- the frontal, parietal, occipital, and temporal lobes. Each lobe controls a specific group of activities. The temporal lobe, located on either side of the brain just above the ear, plays an important role in hearing, language, and memory. The most common type of epilepsy in teens and adults originates in the temporal lobe, the seizure focus.
What Is a Temporal Lobe Resection?
A temporal lobe resection is a surgery performed on the brain to control seizures. In this procedure, brain tissue in the temporal lobe is resected, or cut away, to remove the seizure focus. The anterior (front) and mesial (deep middle) portions of the temporal lobe are the areas most often involved.
Who Is a Candidate for Temporal Lobe Resection?
Temporal lobe resection may be an option for people with epilepsy whose seizures are disabling and/or not controlled by medication, or when the side effects of 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 a Temporal Lobe Resection?
Candidates for temporal lobe resection undergo an extensive pre-surgery evaluation -- including seizure monitoring, electroencephalography (EEG), magnetic resonance imaging (MRI), and positron emission tomography (PET). These tests help to pinpoint the seizure focus within the temporal lobe and to determine if surgery is possible.
What Happens During a Temporal Lobe Resection?
A temporal lobe 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 with 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 for removing the brain tissue. Surgical microscopes also are used to give the surgeon a magnified view of the area of the brain involved. The surgeon utilizes 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 temporal lobe.
In some cases, a portion of the surgery is performed while the patient is in a ''twilight state'' -- awake but under sedation -- so that the patient can help the surgeon find and avoid areas of the brain responsible for vital functions. While the patient is awake, the doctor uses special probes to stimulate different areas of the brain. At the same time, the patient is asked to count, identify pictures, or perform other tasks. The surgeon can then determine 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.