Transcranial direct current stimulation—current level of evidence and potential application scenarios—English version

Abstract

In Europe, anterior thalamic stimulation, vagus nerve stimulation, and focal cortex stimulation are the only approved neurostimulation therapies for drug-resistant epilepsy. However, they are invasive and have limited availability and effectiveness. First reports on the use of transcranial direct current stimulation (tDCS) in epilepsy are promising and give hope for an alternative, non-invasive neurostimulation modality. What is the current level of evidence for the use of tDCS in epilepsy and what could be potential application scenarios? Safety and effectiveness data on the use of tDCS in epilepsy were summarized based on a PubMed literature search. Cathodal tDCS is associated with only mild and transient side effects like paresthesia, tiredness, or difficulties in concentrating. There is no evidence for seizure induction under cathodal tDCS. A single stimulation over 20 min can already induce a seizure frequency reduction of more than 40% in the four subsequent weeks, with effect enhancement under repeated and spaced stimulation using an interstimulation interval of 9–20 min. tDCS would not only extent the spectrum of treatments for epilepsy, it could also allow for reduction of the drug and side-effect load and potentially predict the treatment outcome for implantable devices. The literature data confirm the safe and effective use of cathodal tDCS in patients with drug-resistant epilepsy. Further studies are required to optimize stimulation parameters, to improve effectiveness, and to verify safety and effectiveness aspects in long-term application.