Noninvasive brain stimulation protocols in the treatment of epilepsy: current state and perspectives

In epileptic seizures, there is an enhanced probability of neuronal networks to fire synchronously at high frequency, initiated by a paroxysmal depolarisation shift. Reducing neuronal excitability is a common target of antiepileptic therapies. Beyond or in addition to pharmacological interventions, excitability-reducing brain stimulation is pursued as an alternative therapeutic approach. Hereby, noninvasive brain stimulation tools, such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), have gained increased interest as efficient tools to modulate cortical excitability and activity. In animal models, stimulation-induced cortical excitability diminution has been shown to be suited to reduce seizures. Clinical studies conducted to date, however, have shown mixed results. Reasons for this, as well as possible optimization strategies that might lead to more efficient future stimulation protocols, will be discussed.