Designing next-generation subscalp devices for seizure monitoring: A systematic review and meta-analysis of established extracranial hardware

• Published in: Epilepsy research 2024-05, Vol.202, p.107356-107356, Article 107356
• Main Authors: Barlatey, Sabry L., Kouvas, George, Sobolewski, Aleksander, Nowacki, Andreas, Pollo, Claudio, Baud, Maxime O.
• Format: Article
• Language: English
• Subjects: Deep Brain Stimulation - adverse effects; Deep Brain Stimulation - instrumentation; Deep Brain Stimulation - methods; Electrodes, Implanted - adverse effects; Electroencephalography; Electroencephalography - instrumentation; Electroencephalography - methods; Epilepsy monitoring; Humans; Neuro-engineering; Neurostimulation; Seizures - diagnosis; Subscalp devices
• ISSN: 0920-1211; 1872-6844
• DOI: 10.1016/j.eplepsyres.2024.107356

Implantable brain recording and stimulation devices apply to a broad spectrum of conditions, such as epilepsy, movement disorders and depression. For long-term monitoring and neuromodulation in epilepsy patients, future extracranial subscalp implants may offer a promising, less-invasive alternative to intracranial neurotechnologies. To inform the design and assess the safety profile of such next-generation devices, we estimated extracranial complication rates of deep brain stimulation (DBS), cranial peripheral nerve stimulation (PNS), responsive neurostimulation (RNS) and existing subscalp EEG devices (sqEEG), as proxy for future implants. Pubmed was searched systematically for DBS, PNS, RNS and sqEEG studies from 2000 to February 2024 (48 publications, 7329 patients). We identified seven categories of extracranial adverse events: infection, non-infectious cutaneous complications, lead migration, lead fracture, hardware malfunction, pain and hemato-seroma. We used cohort sizes, demographics and industry funding as metrics to assess risks of bias. An inverse variance heterogeneity model was used for pooled and subgroup meta-analysis. The pooled incidence of extracranial complications reached 14.0%, with infections (4.6%, CI 95% [3.2 – 6.2]), surgical site pain (3.2%, [0.6 – 6.4]) and lead migration (2.6%, [1.0 – 4.4]) as leading causes. Subgroup analysis showed a particularly high incidence of persisting pain following PNS (12.0%, [6.8 – 17.9]) and sqEEG (23.9%, [12.7 – 37.2]) implantation. High rates of lead migration (12.4%, [6.4 – 19.3]) were also identified in the PNS subgroup. Complication analysis of DBS, PNS, RNS and sqEEG studies provides a significant opportunity to optimize the safety profile of future implantable subscalp devices for chronic EEG monitoring. Developing such promising technologies must address the risks of infection, surgical site pain, lead migration and skin erosion. A thin and robust design, coupled to a lead-anchoring system, shall enhance the durability and utility of next-generation subscalp implants for long-term EEG monitoring and neuromodulation. •Implantable subscalp devices will shift seizure monitoring to an ambulatory setting.•Severe complications are unlikely following the implantation of subscalp devices for long-term EEG recording.•Minor extracranial complications are frequent with DBS, PNS, RNS and sqEEG.•Careful design of next-generation subscalp EEG devices shall increase their safety, durability, and clinical us