A seizure (often called a fit, spell, convulsion, or attack) is a visible sign of a problem in the electrical system that controls your brain. A single seizure can have many causes.
Those who continue to have unprovoked seizures may have a chronic disorder called epilepsy. The term "seizure disorder" is often used as another way to describe epilepsy.
Epilepsy is a disorder of the brain in which seizures occur repeatedly.
A seizure is caused by an abnormal electrical discharge in the brain. This abnormal "short circuit" can cause a change in behavior without your being aware of what is happening. During a seizure you may fall down, stare off into space, or make jerking movements. Some people get a warning, called an aura that tells them when a seizure is about to happen. You cannot control what's happening while the seizure is occurring.
The most common seizure types are classified as either Partial or Generalized.
SURGICAL TREATMENT OPTIONS FOR EPILEPSY
Epilepsy surgery is performed to treat seizures that are uncontrolled with medication. About 30% of people with epilepsy are not controlled with medication. "Medically intractable seizures" are defined as persistent seizures despite trials of three or more appropriate antiepileptic drugs, alone or in combination. People with intractable seizures may be candidates for surgical treatment to achieve better seizure control to:
Surgical results can be considered Curative (stopping the seizures) or Palliative (restricting the spread of the seizure). The type of surgery performed depends on the type of seizures and where they begin in the brain.
CURATIVE PROCEDURES
Curative procedures are performed when tests consistently point to a specific area of the brain where the seizures begin such as lobectomy, cortical excision, or Hemispherectomy aim to remove the area of the brain (seizure focus) causing seizures. The goal is to remove all of the seizure focus area without causing loss of brain function:
Temporal Lobectomy is the most common type of surgery for people with temporal lobe epilepsy. It removes a part of the anterior temporal lobe along with the amygdala and hippocampus. A temporal lobectomy leads to a significant reduction or complete seizure control about 70% to 80% of the time. However, memory and language can be affected if this procedure is performed on the dominant hemisphere.
Cortical Excision is the second most common type of epilepsy surgery. It removes the outer layer (cortex) of the brain at the seizure focus area. About 40% to 50% of patients have better seizure control.
Hemispherectomy involves the removal of the brain's outer layer (cortex) and anterior temporal lobe on one half of the brain. It is usually performed in children who suffer intractable seizures, have a damaged hemisphere, and experience weakness on one side of the body. Surgery may control seizures for nearly 80% of these patients. Patients often improve in cognitive functioning, attention span, and behavior.
PALLIATIVE PROCEDURES
Palliative procedures are performed when a seizure focus cannot be determined or it overlaps brain areas critical for movement, speech, or vision. Palliative procedures, such as Corpus Callosotomy or Vagus Nerve Stimulation (VNS), aim to reduce seizure frequency or severity.
Corpus Callosotomy prevents the spread of generalized seizures from one side of the brain to the other by disconnecting the nerve fibers across the corpus callosum. During surgery the anterior two thirds of the corpus callosum is sectioned. On occasion, a second surgery is performed to cut the posterior one third if the patient does not improve. This surgery is not curative. Rather, it prevents the spread and reduces seizure severity. Some patients experience disconnection syndrome after a complete callosotomy. They may have right-left confusion with motor problems, apathy, or mutism.
Multiple Subpial Transections create small incisions in the brain to interfere with the spread of seizure impulses. This technique is used when the seizure focus is located in a vital area that cannot be removed. It may be used alone or in combination with a lobectomy.
Vagus Nerve Stimulation (VNS) involves implantation of a device that produces electrical signals to prevent seizures. VNS is similar to a heart pacemaker. A wire (lead) is wrapped around the vagus nerve in the neck. The wire is connected to a generator-battery implanted under the skin near the collarbone. The generator is programmed to produce intermittent electrical signals that travel along the vagus nerve to the brain. In addition, some patients may turn on the device with a magnet when feeling a warning (aura) that a seizure is about to start. VNS is not a cure for epilepsy, it does not work for everyone, and it does not replace the need for anti-epileptic drugs. This procedure is reserved for those who are not candidates for potentially curative brain surgery. VNS reduces seizure frequency by about 30% (similar to the results of the newer AEDs). Common side effects are a tingling sensation in the neck and mild hoarseness in the voice, both of which occur only during stimulation.
Your surgeon will review all testing performed to decide if surgery is the best treatment option for you. All tests should point to a single region in the brain as the source for seizures. If this is the case, and the region of seizure onset is a safe distance away from areas of the brain that control language, movement, and vision, then surgery can be recommend to reduce or eliminate seizures.
THE PROCEDURE
The surgery generally takes 3 to 4 hours.
You will lie on your back on the operative table and be given anesthesia. Once asleep, your head is placed in a skull fixation device attached to the table that holds your head in position during the surgery. Depending on where the incision will be made, your hair may be shaved.
After your scalp is prepped, the surgeon will make a skin incision to expose the skull. A circular opening in the skull, called a CRANIOTOMY, is drilled. This bony opening exposes the protective covering of the brain, called the dura mater, which is opened with scissors.
Depending on your specific case, intraoperative EEG recording and stimulation with subdural electrodes may be performed to map brain areas , or reconfirm the epileptic zone, particularly how much of the lateral temporal cortex is involved.
Using a small electrical probe, the surgeon tests locations on the brain’s surface one after another to create a map of functions.
During mapping, areas involved with movement can be identified electrically even if the patient is under anesthesia. However, to map areas such as language, sensation, or vision, the patient is awakened to be able to communicate with the surgeon.
Local anesthesia and numbing agents are given so you won’t feel any pain. Looking through an operative microscope, the surgeon gently retracts the brain and opens a corridor to the seizure focus area.
The surgeon then removes that area of brain where seizures occur.
The retractors are removed and the dura is closed with sutures. The bone flap is replaced and secured to the skull with titanium plates and screws. The muscles and skin are sutured back together.
The surgical preparation, discharge and post operativerecouperation procedure is similar to that of patients undergoing a CRANIOTOMY.
Risks
No surgery is without risks. General complications of any surgery include bleeding, infection, blood clots, and reactions to anesthesia. Specific complications related to a craniotomy may include:
Specific complications may include: