The Different Epilepsy Procedures
There are several types of surgical procedures used in the evaluation and treatment of patients with epilepsy. The specific procedure that is appropriate for a patient will depend on the results their evaluation.
For patients with intractable epilepsy, where the location of the seizure focus has been found and determined to be safe to remove, a focal resection of the brain may be appropriate. The location and size of resection is determined by the evaluation. It can range from removing a small lesion (lesionectomy), a small piece of the cerebral cortex (corticectomy), or a large region of the brain, possibly a whole lobe of the brain (a lobectomy) and, in some cases, even most/all of one side of the brain (hemispherectomy).
For some patients whose seizure focus has been precisely identified, an MRI-guided laser ablation of the focus may be an option. This is performed by passing a fiber optic probe into the seizure focus and heating the probe using a laser to ablate the tissue. This is typically reserved for cases where the seizure focus is fairly small and can be clearly identified on an MRI scan.
For some patients with certain seizure types (tonic, atonic or generalized tonic-clonic) that lead to injury/fall, if a single seizure focus cannot be identified, a corpus callosotomy may prevent falls/injuries associated with seizures. In this procedure, the two sides of the brain are partially disconnected by cutting the corpus callosum, the main connection between the two sides. This prevents seizures from simultaneously affecting both sides of the brain and will often prevent falls/injuries.
The vagus nerve stimulator is a type of neurostimulator meant to reduce the frequency and severity of seizures. It can significantly reduce the frequency of seizures over a period of several months after implantation. Because it does not make the patient seizure free, it is typically reserved for patient who are not candidates for a surgical resection to fully control their seizures. The patient can also activate the device using a magnet to give an extra stimulation when they are having a seizure or about to have a seizure. Newer versions of the device can also sense changes in heart rate to try to detect when a seizure is happening and give and extra stimulation. The device is programmed by the epileptologist using a handheld wand and computer.
The responsive neurostimulator is a device that is implanted in the patient’s skull with electrodes placed in/near their seizure focus. It is intended for patient have a seizure focus located in part of the brain that cannot be safely removed or have two distinct seizure foci. The electrodes are used to record seizure activity continuously. The device is programmed (using a handheld wand and computer) to recognize the start of that patient’s seizure and to quickly give a stimulation to the brain to keep the activity from spreading.
The deep brain stimulator is a device that is implanted in the chest with wire electrodes that end in a part of the brain called the thalamus. It can be programmed to deliver a stimulus to the thalamus at different intensities and frequency. The DBS is used in patient with intractable focal seizures to reduce the frequency and severity of seizures.