Neurostimulation targeting the epileptic focus: Current understanding and perspectives for treatment

• Published in: Seizure (London, England) England), 2024-04, Vol.117, p.183-192
• Main Authors: Schulze-Bonhage, Andreas, Nitsche, Michael A., Rotter, Stefan, Focke, Niels K., Rao, Vikram R.
• Format: Article
• Language: English
• Subjects: AC stimulation; DC stimulation; Electric Stimulation Therapy - methods; Epilepsy - therapy; Epileptic focus; Epileptic network; Humans; Neurostimulation
• ISSN: 1059-1311; 1532-2688
• DOI: 10.1016/j.seizure.2024.03.001

•Focus stimulation targeting the dynamics of the epileptogenic zone is clinically available using intracranial responsive neurostimulation or epicranial focal cortex stimulation.•There is pathophysiological and modeling evidence for seizure suppressive effects of both, AC and DC stimulation of the epileptogenic zone.•Networks beyond the epileptogenic zone are relevant for targeting of neurostimulation and for its efficacy.•Target areas for neurostimulation (“neuromodulation zones”) may include the epileptogenic zone but also remote areas modulating the focus region. For the one third of people with epilepsy whose seizures are not controlled with medications, targeting the seizure focus with neurostimulation can be an effective therapeutic strategy. In this focused review, we summarize a discussion of targeted neurostimulation modalities during a workshop held in Frankfurt, Germany in September 2023. Topics covered include: available devices for seizure focus stimulation; alternating current (AC) and direct current (DC) stimulation to reduce focal cortical excitability; modeling approaches to simulate DC stimulation; reconciling the efficacy of focal stimulation with the network theory of epilepsy; and the emerging concept of ‘neurostimulation zones,’ which are defined as cortical regions where focal stimulation is most effective for reducing seizures and which may or may not directly involve the seizure onset zone. By combining experimental data, modeling results, and clinical outcome analysis, rational selection of target regions and stimulation parameters is increasingly feasible, paving the way for a broader use of neurostimulation for epilepsy in the future.