Here are some highlights from the latest issue of Epilepsy Currents Vol. 15, no. 4:
• Benefits, safety of deep-brain stimulation withstand the test of timeDeep-brain stimulation of the anterior nucleus of the thalamus (ANT) can provide relatively safe and long-lasting seizure control in patients with drug-resistant epilepsy, according to a 2015 study by Salanova and colleagues in Neurology. A Commentary by Mohamad Z. Koubeissi, MD, explores these findings from a 5-year follow up study of the electrical Stimulation of the Anterior Nucleus of Thalamus for Epilepsy (SANTE) trial – one of the largest blinded, randomized, controlled trials to study electrical stimulation in patients with intractable epilepsy. Koubeissi notes that ANT deep-brain stimulation may offer greater benefits to patients with temporal lobe epilepsy compared with frontal lobe epilepsy, with 76% and 59% respective reductions in seizure frequency 5 years after device implantation. The Neurology report confirms and expands findings from a 2-year follow up of the SANTE trial suggesting that participants’ seizure control improved with time. According to the Commentary, the benefits of ANT simulation appear similar to those of VNS and the NeuroPace Responsive Neurostimulator.
• Optogenetic studies suggest interneurons may be to blame for epileptiform activityThe combined use of genetic and optical technologies, known as optogenetics, allows researchers to control certain cell populations. Silencing excitatory neurons, for example, can suppress seizure activity. But whether similar effects can be attained through the activation of interneurons, which transmit electrical impulses between neurons, remains unclear. A Commentary by Jamie L. Maguire, PhD, notes that highly reproducible in vitro studies – including a 2014 report in Journal of Neuroscience by Ellender and colleagues – suggest that interneuron activation exacerbates a type of epileptiform activity known as afterdischarges. But in vivo studies found the opposite to be true: Activated interneurons appeared to mediate antiseizure effects. These conflicting reports highlight the complexity of neuronal networks in vivo and emphasize the need for more studies to clarify the role of interneurons in epilepsy, Ellender notes.
• Parsing the effects of exercise and enrichment on epilepsyToys, tunnels, ladders and other forms of environmental enrichment may promote normal hippocampal function and reduce the burden of epilepsy in rodents, according to a 2014 Experimental Neurology study by Morelli and colleagues. A Commentary by Geoffrey G. Murphy, PhD, explores the possible mechanisms mediating the effects of environmental enrichment on seizure progression, noting that the findings support a model in which seizure onset begins earlier than previously appreciated. The Commentary poses a number of questions that should be addressed in future studies before attempting to extrapolate these findings to humans. In particular, determining whether the benefits are due to increased exercise versus cognitive stimulation, and whether they’re mediated by stress reduction or other means is key.
• Casting doubt on traditional approaches to epilepsy surgeryA Commentary by Lara Jehi, MD, offers insights that may help explain why the long-term outcomes of temporal lobe epilepsy surgery have improved minimally since 1952. Jehi notes that surgical failure in patients with drug-resistant epilepsy is often attributed to the idea that seizure-prone tissue was not properly identified or removed from the brain. But this so-called “find and cut” model of epilepsy surgery may be hindering progress in the field, Jehi advises. Her Commentary refers to two notable imaging studies – a 2015 report by Keller and colleagues in Annals of Neurology and a 2015 report by Bonilha and colleagues in Neurology – that illuminate the neural networks underlying epilepsy. The real question, Jehi proposes, is whether knowledge of those extensive networks should be used to expand the find-and-cut mold so that it encompasses all brain tissues affected by the network – or whether the new information should incite a deeper appreciation for the pathogenic processes underlying epilepsy, which appear to be infinitely more complex than previously thought.
Epilepsy Currents is a literature surveillance publication, including brief expert commentary on abstracts in selected basic science and clinical topics selected by the editorial board. The journal is available online to AES members and non-members.
About EpilepsyThe epilepsies affect 50 million people worldwide, including three million in the United States. The disorder can have a single specific, well‐defined cause, such as a head injury, or manifest as a syndrome with a complex of symptoms. It is the third most common neurological disorder after Alzheimer’s disease and stroke.
About the American Epilepsy Society The American Epilepsy Society is a medical and scientific society whose members are professionals from private practice, academia and government engaged in both research and clinical care for people with epilepsy. For more than 75 years, AES has been unlocking the potential of the clinical and research community by creating a dynamic global forum where professionals can share, learn and grow. AES champions the use of sound science and clinical care through the exchange of knowledge, by providing education and by furthering the advancement of the profession. For additional information, visit aesnet.org.
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