Up to 30-40% of patients with epilepsy (around 70 million people worldwide) do not respond to anti-seizure medications. A significant proportion of patients with medically refractory focal epilepsy can benefit from a surgical treatment, which offers the chance of seizure remission in many cases or decrease of seizure frequency and severity. Unfortunately, epilepsy surgery is not possible for some patients due to several conditions such as multifocal seizures, involvement of eloquent areas, associated diseases and surgical risk factors. However, alternative non-pharmacological treatments, other than resective surgery, can be a therapeutic option for these patients.
Advances in neurophysiology, neuroimaging and epilepsy surgery technologies have led to the development of new pre-surgical diagnostic methods and new surgical approaches. A precise definition of the epileptogenic network can create a surgical opportunity for complex refractory epilepsies. For patients who are not good candidates for resective treatments, the evolution in neuromodulation devices and other non-resective surgical procedures can offer good chances of seizure control and improvement in quality of life.
During pre-surgical evaluation for conditions such as multifocal or bitemporal epilepsy, periventricular nodular heterotopia (PNH), tuberous sclerosis complex (TSC), Rasmussen encephalitis, seizures arising from eloquent areas, the localization of the ictal onset zone encompasses diagnostic challenges that can be overcome by means of advanced neurophysiological and radiological methods. High-Density Electroencephalography (HD-EEG), magnetoencephalography (MEG), EEG-fMRI, stereoelectroencephalography (SEEG), subdural grids (SDG), electrocorticography (ECoG), detection of high frequency oscillations (HFOs): these invasive and non-invasive recordings can allow for the epileptogenic zone identification of difficult-to-localize focal epilepsies.
Furthermore, such complex forms of intractable focal epilepsies are challenges for resective epilepsy surgery. Therefore, recent enhancements in surgical techniques, such as laser interstitial thermal therapy (LITT), focus ultrasound (FUS), radiofrequency thermocoagulation (RF-THC), radiosurgery (cyber-knife, gamma-knife) can enable surgical treatment for these patients, targeting the epileptogenic zone even when this is difficult to approach using classical surgical procedures. Moreover, these new techniques can minimize surgical risks, making a surgical treatment possible also for patients who cannot undergo conventional surgery because of comorbidities determining unacceptable perioperative morbidity.
For patients without possibility of surgical access to the primary epileptogenic zone, neuromodulation therapies have been an option for several years. However, new developments in technologies and the increasing knowledge of the circuits involved in neuromodulation have expanded the accomplishment of these treatments. The main advanced neurostimulation technologies are Responsive Neurostimulation (RNS®), Deep Brain Stimulation (DBS) and Vagal Nerve Stimulation (VNS).
This Research Topic is intended to collect key research findings in the field of epilepsy surgery and, more extensively, of non-pharmacological treatments in complex scenarios of drug-resistant epilepsies. In particular, we aim to highlight the role of advancements in neurophysiological pre-surgical assessments and in new surgical techniques. We thereby welcome contributions in form of Original Research articles, Reviews, Case Reports and Clinical Trials relating, but not limited to the following topics:
1) Advanced neurophysiological methods: HD-EEG, MEG, EEG-fMRI, SEEG, SDG, ECoG, HFOs
2) Resective epilepsy surgery: multistage surgery (e.g. TSC), “Palliative” or “Non-curative” resective surgery” (e.g. multifocal/bitemporal epilepsy), surgery of eloquent areas.
3) Non-resective surgery: LITT, FUS, RF-THC, Radiosurgery
4) Neurostimulation: RNS, DBS, VNS
5) Surgical procedures for patients with refractory epilepsy and associated comorbidities.
We would like to acknowledge that Dr. Ricardo Amorim Leite, University of Iowa, Iowa City, United States, has acted as a coordinator and has contributed to the preparation of the proposal for this Research Topic. 