Who Should Be Evaluated for Epilepsy Surgery
What is epilepsy surgery?
Epilepsy surgery is a brain operation to control epileptic seizures. There are different types of operations for different types of epilepsy.
In epilepsy surgery, the surgeon removes the abnormal portion of brain that is causing the seizures. Brain tumors, vascular (blood vessel) abnormalities, old strokes, and congenital (inherited) irregularities might also be treated if they are believed to be causing the seizures.
Who is a candidate for epilepsy surgery?
In general, epilepsy surgery may be considered in people of any age. The best candidates for epilepsy surgery are:
- People with epileptic seizures that cannot be controlled satisfactorily with medication, and whose lives would be improved if seizures were controlled. (The definition of “satisfactory” control is different for every person.)
- People with a brain abnormality that can be identified as the cause of seizures. Some abnormalities such as brain tumors may need surgery even if seizures are well controlled with medication.
Which types of surgeries and procedures are considered?
Focal resective surgery is performed in people with partial epilepsy, in which seizures arise from a small part of the brain. Partial epilepsy may be caused by a scar from birth, injury or head trauma, brain tumors, arteriovenous vascular malformations (a tangle of blood vessels resulting in fewer than normal connections between capillaries), infections, or abnormal brain development.
In focal resective surgery, a small part of the brain is removed to preserve important neurological functions such as movement, sensation (feeling), speech, and memory. The most common location of this surgery is in the temporal lobe (under the temple).
Hemispherectomy is performed in people with abnormalities of one hemisphere (side) of the brain. Conditions such as Sturge-Weber disease, Rasmussen’s encephalitis, hemimegalencephaly, or perinatal stroke may injure a large area on just one side of the brain. People with these disorders usually have severe neurologic problems, such as paralysis and loss of feeling on one side of the body. With this procedure, a portion of the damaged brain is removed, and the rest of the hemisphere is disconnected from the “good” portions of the brain to keep the seizures from spreading.
Callosotomy involves cutting part of the corpus callosum, a large bundle of nerve fibers that connect the two sides of the brain. The goal is to keep seizures from spreading from one side of the brain to the other. Callosotomy is usually performed in people with severe generalized tonic (stiffening) or atonic (limp) seizures that cause falling and injuries ("drop attacks").
Subdural electrode insertion involves placing electrodes directly in contact with the brain in order to better pinpoint the region(s) of the brain that cause seizures. They also can be used to stimulate the underlying brain tissue, and verify the presence of cortex that supports important motor or language function. This technique is especially useful in patients who have medically intractable (stubborn) epilepsy and require functional brain mapping in addition to seizure onset information.
Stereoelectroencephalography (SEEG) is a “less invasive” method for mapping seizures in which thin recording probes are precisely placed into deep regions in the brain. The patient usually has several studies before the probes are placed, including MRI, PET scans, and magnetoencephalogram (MEG). This technique allows safe, precise, and three-dimensional mapping of seizure activity in brain regions that cannot be seen with other mapping techniques. It is especially useful for patients who need recordings from deep areas in the brain and in patients with “normal” MRI.
Vagal nerve stimulation involves placing an electrode on the left vagus nerve and a generator under the skin over the left chest. The device is then programmed to deliver periodic electrical impulses to the vagus nerve, which are then sent via the brainstem to the cerebral cortex. The device may reduce seizures in approximately 40 to 50 percent of patients. It is generally intended as an option for patients who cannot have resective surgery.
Responsive neurostimulation is an investigational technique being studied at Cleveland Clinic. This treatment identifies seizure activity with an electrode and a computer implanted in the patient’s brain. Once a seizure occurs, the device fires an electrical impulse into the region of the brain responsible for the seizure.