Options chirurgicales pour l'épilepsie chez l'adulte
L'épilepsie demeure l'un des troubles neurologiques les plus fréquents, touchant aussi bien les adultes que les enfants. Aux États-Unis, plus de deux millions de personnes en sont atteintes. Environ 30 % des patients épileptiques sont considérés comme « résistants aux traitements médicamenteux », c'est-à-dire qu'ils continuent de présenter des crises malgré un traitement médicamenteux. C'est chez ces patients que les crises ont l'impact le plus important sur leur qualité de vie, notamment sur leurs relations avec leurs proches et leurs collègues, ainsi que sur leur capacité à travailler et à conduire. On estime que près de la moitié de ces patients atteints d'épilepsie réfractaire aux traitements médicamenteux pourraient bénéficier d'une intervention chirurgicale à visée diagnostique ou thérapeutique.
Candidature chirurgicale
Les patients atteints d'épilepsie pharmacorésistante ont, par définition, présenté un échec thérapeutique avec au moins deux médicaments antiépileptiques. Or, il arrive souvent que plusieurs médicaments soient essayés pendant une période excessivement longue. Après l'échec de deux traitements antiépileptiques appropriés, les chances d'obtenir une absence totale de crises grâce à la seule médication sont extrêmement faibles. Des effets secondaires importants des médicaments peuvent également justifier une intervention chirurgicale. De plus, tout patient présentant une tumeur, une malformation vasculaire ou toute autre lésion cérébrale à l'origine de crises d'épilepsie doit être examiné par un chirurgien spécialisé dans l'épilepsie. Afin de déterminer l'éligibilité d'un patient à la chirurgie de l'épilepsie, un bilan complet est réalisé, comprenant un enregistrement vidéo-EEG, une imagerie anatomique (IRM) et fonctionnelle (TEP, TEMP, MEG), ainsi que des tests neuropsychologiques. Ce bilan initial non invasif, dit « de phase 1 », offre une vue d'ensemble du syndrome épileptique du patient.
Surgical Treatment
Stereoelectroencephalography (Stereo-EEG)
Some patients require no further testing and go on directly to surgery. The type of surgery is based on the epileptic syndrome, imaging, and electrophysiological findings. For other patients, non-invasive testing may fail to pinpoint the exact seizure focus and additional diagnostic monitoring is required before proceeding with surgical treatment. For these patients, Stereo-EEG may be necessary to further define the seizure focus. Stereo-EEG is the surgical implantation of electrodes into the brain to better localize the seizure focus. Dr. Faraji uses robotic assistance with the ROSA system to accurately and efficiently place these electrodes. Typically 10-15 electrodes are implanted and each electrode is the size of a spaghetti noodle. The electrodes are implanted in the operating room and the patient is monitored in the Epilepsy Monitoring Unit (EMU) for about a week to record seizures. The electrodes can also be stimulated to identify important functional areas of the brain, such as those involved in language. This data is reviewed by the entire epilepsy team and a recommendation for surgery can be made based off these results. Removal of the electrodes takes about 15 minutes and is performed in the operating room under light sedation. You will be kept overnight for observation and discharged home the following day. The risk of Stereo-EEG is published and is low at about 1%, but no surgery is without risk. There is a risk of bleeding and infection primarily. There is also a risk that despite our best efforts, we are unable to localize the part of your brain responsible for seizures.
Craniotomy for Resection of a Seizure Focus
Epilepsy surgery typically consists of a resective procedure, which is most likely to result in a cure since the goal is to remove the abnormal seizure focus itself. The most common type of resection is an anterior temporal lobectomy. Outcomes following resective surgery for the treatment of epilepsy have markedly improved over the last few decades. For patients with temporal lobe epilepsy, it is now widely accepted that surgery is superior to prolonged medical therapy. Frequently with this type of surgery, the proportion of properly selected patients who are seizure free after surgery can be above 70%. While the other types of resective surgery are less likely to have a seizure free outcome, the numbers are proportionately better than medical therapy alone. Seizure free outcomes range from 30-70% for surgery outside the temporal lobe.
Laser Ablation
Laser Interstitial Thermal Therapy (LITT) is an alternative to surgical resection of a seizure focus. LITT is a procedure, like an open surgery, that can cure a patient's epilepsy. Rather than surgically removing a seizure focus, the seizure focus is ablated using heat generated from a laser at the tip of a very thin probe. This minimally invasive procedure is performed through an incision about the width of a pencil's eraser and most patients are discharged home within 1 day.
Responsive Neurostimulation (RNS)
In 2013, the FDA approved the use of RNS for the treatment of adults with medically refractory focal onset seizures arising from one or two foci in the brain. RNS is a long-awaited "closed-loop" treatment for a large group of patients, who were previously determined not to be candidates for epilepsy surgery, such as those patients with multifocal epilepsy or with seizures arising from areas the brain that can not be safely resected. RNS continuously monitors the brain's electrical activity and sends a brief pulse of stimulation directly to the brain when a seizure or seizure-like activity is detected. Doctors specifically trained in RNS program the device and gradually train it to detect specific patterns unique to a patient's seizure. Patient's upload data from the RNS to their physician or swipe a magnet over the device when they have a seizure, as it helps the training process. Although this surgery is unlikely to be curative like surgical resection, RNS has been shown to reduce seizure frequency by approximately 68% at 1 year and seizure reduction continues to improve with time to more than 82% after 3-6 years of use. Patients reported significant improvement in their quality of life with RNS.
Deep Brain Stimulation (DBS)
DBS is a brain stimulator that has been used to treat movement disorders since the 1990's. It has been more recently approved to treat intractable epilepsy. DBS has been shown to reduce seizure frequency by 41-56% at 1-2 years after surgery, and the seizure reduction continues to improve with time. It is indicated to treat patients with medically intractable epilepsy who are not candidates for resection of their seizure focus.
Vagal Nerve Stimulation (VNS)
VNS has been shown to reduce seizures by half or more in about 40% of patients 1 year after surgery and seizure reduction continues to improve over time. It is indicated for patients with medically intractable epilepsy who are not candidates for other types of surgical intervention. The device consists of a wire that is wrapped around the vagus nerve in the neck and a battery that is placed in the chest. VNS does not stimulate the brain directly and this surgery can be performed as an outpatient.
Other Surgical Approaches
Other less commonly performed surgeries include multiple subpial transections (MST), corpus callosotomies, and functional hemispherectomies. These surgeries are palliative rather than curative, since they do not eliminate the seizures but rather interrupt the propagation of seizures. Despite that, these procedures can improve a patient's quality of life by decreasing the frequency and intensity of seizures.
Future Options
The utility of epilepsy surgery is likely to continue to grow in the future, since the majority of patients who are potential surgical candidates have not been properly evaluated or treated. It is estimated that less than 3% of patients who could benefit from a surgery actually undergo a surgery! With improved awareness of the benefits of surgery and ongoing technological advances, surgery for epilepsy is now well-established and readily is identified as the optimal treatment for many forms of intractable seizures.
Cutting-edge, minimally-invasive and personalized approaches form the cornerstone of Dr. Faraji's practice. He completed a dedicated fellowship in epilepsy surgery and any patient, family member or interested individual is encouraged to contact our practice for more information regarding the modern standards of diagnostic and therapeutic epilepsy care.
