There are different technical means for suppressing the electrical activity in an epileptogenic part of the brain, and the neurosurgeon decides which is the safest and most effective technique for each individual case based on the results of the patient’s tests and recommendations of the Epilepsy Unit.
The most effective option is to remove the brain lesion or focal point where seizures originate. This surgery does not usually require shaving the head. The surgery is usually performed with the patient under general anesthesia, although in specific cases where it is necessary to verify that no essential function, such as language, is affected, it is necessary to perform the operation with the patient under local anesthesia and with light sedation.
Epilepsy surgery intended to remove an epileptogenic zone is performed with a standard craniotomy, opening both the skull and the brain membranes. The surgeon will make an incision in the scalp, and with special tools will remove a piece of the skull, referred to as a bone flap, which will be replaced at the end of the surgery.
After this, the epileptogenic area is resected (removed) with microsurgical techniques. Intraoperative monitoring with direct brain EEG recording may be necessary to increase the chances of removal of all epileptic tissue.
The surgeon will try to remove as much epileptic tissue as possible, at the same time, trying not to affect the brain functions that reside in that region of the brain. The difficulty and risks of surgery depend on the size and location of the area that is to be removed.
Although it is much less common, there are some cases of catastrophic childhood epilepsies in which the epileptic region of the brain is very extensive, and it is not advisable to remove the entire seizure-producing portion of the brain. In these situations, the option is to surgically disconnect that region to avoid impact on the rest of the brain.
Once there is no more bleeding on the surface, the membranes that cover the brain are closed and the bone fragment that was removed is replaced and fixed. Epilepsy surgeries usually last a minimum of 3 or 4 hours.
When epileptic tissue is located in a deep and hard-to-reach region of the brain, the technique of laser ablation may be used. This type of surgery is performed with the patient under general anesthesia, and consists of applying high-intensity laser light to the deep epileptogenic zone through an optical fiber that has previously been implanted into the patient using a stereotactic technique, a neurosurgical methodology that allows devices to be implanted in deep regions of the brain with very high precision and safety. The laser light causes an increase in temperature in the surrounding region that inactivates the brain tissue causing the seizures. The state of the brain and temperature are monitored at all times with magnetic resonance imaging. In these cases, the hole in the skin and skull is a few millimeters, so the patient can be discharged in one or two days after laser ablation.
Finally, in patients with drug-resistant epilepsy who cannot benefit from epilepsy surgery that involves removing, disconnection, or ablation of part of the brain, there are neurostimulation or electrical neuromodulation (deep brain stimulation) techniques that may be useful. These techniques consist of applying electrical stimulation to the nervous system (in the brain or in a cranial nerve, depending on the case). Although these techniques cannot cure epilepsy, they can reduce the number or intensity of the seizures, which can provide comfort and increase the quality of life for patients with severe cases and for whom there is currently no other therapeutic option.