Karimi Fariba, Cassarà Antonino M, Capstick Myles, Kuster Niels, Neufeld Esra
Foundation for Research on Information Technologies in Society (IT'IS), Zurich, Switzerland.
Department of Information Technology and Electrical Engineering, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.
J Neural Eng. 2025 Feb 13;22(1). doi: 10.1088/1741-2552/ad8efa.
Non-invasive brain stimulation (NIBS) methodologies, such as transcranial electric stimulation (tES) are increasingly employed for therapeutic, diagnostic, or research purposes. The concurrent presence of active/passive implants can pose safety risks, affect the NIBS delivery, or generate confounding signals. A systematic investigation is required to understand the interaction mechanisms, quantify exposure, assess risks, and establish guidance for NIBS applications.We used measurements, simplified generic, and detailed anatomical modeling to: (i) systematically analyze exposure conditions with passive and active implants, considering local field enhancement, exposure dosimetry, tissue heating and neuromodulation, capacitive lead current injection, low-impedance pathways between electrode contacts, and insulation damage; (ii) identify risk metrics and efficient prediction strategies; (iii) quantify these metrics in relevant exposure cases and (iv) identify worst case conditions. Various aspects including implant design, positioning, scar tissue formation, anisotropy, and frequency were investigated.At typical tES frequencies, local enhancement of dosimetric exposure quantities can reach up to one order of magnitude for deep brain stimulation (DBS) and stereoelectroencephalography implants (more for elongated passive implants), potentially resulting in unwanted neuromodulation that can confound results but is still 2-3 orders of magnitude lower than active DBS. Under worst-case conditions, capacitive current injection in the active implants' lead can produce local exposures of similar magnitude as the passive field enhancement, while capacitive pathways between contacts are negligible. Above 10 kHz, applied current magnitudes increase, necessitating consideration of tissue heating. Furthermore, capacitive effects become more prominent, leading to current injection that can reach DBS-like levels. Adverse effects from abandoned/damaged leads in direct electrode vicinity cannot be excluded.Safety related concerns of tES application in the presence of implants are systematically identified and explored, resulting in specific and quantitative guidance and establishing basis for safety standards. Furthermore, several methods for reducing risks are suggested while acknowledging the limitations (see section4.5).
非侵入性脑刺激（NIBS）方法，如经颅电刺激（tES），越来越多地用于治疗、诊断或研究目的。有源/无源植入物的同时存在可能会带来安全风险，影响NIBS的传递，或产生混淆信号。需要进行系统的研究，以了解相互作用机制、量化暴露、评估风险，并为NIBS应用建立指导原则。我们使用测量、简化的通用模型和详细的解剖模型来：（i）系统地分析有源和无源植入物的暴露条件，考虑局部场增强、暴露剂量学、组织加热和神经调节、电容性导线电流注入、电极触点之间的低阻抗通路以及绝缘损坏；（ii）识别风险指标和有效的预测策略；（iii）在相关暴露案例中量化这些指标；（iv）识别最坏情况条件。研究了包括植入物设计、定位、瘢痕组织形成、各向异性和频率等各个方面。在典型的tES频率下，对于深部脑刺激（DBS）和立体脑电图植入物，剂量学暴露量的局部增强可达一个数量级（对于细长的无源植入物更高），这可能会导致不必要的神经调节，从而混淆结果，但仍比有源DBS低2 - 3个数量级。在最坏情况下，有源植入物导线中的电容性电流注入可产生与无源场增强类似大小的局部暴露，而触点之间的电容性通路可忽略不计。高于10 kHz时，施加的电流大小会增加，需要考虑组织加热。此外，电容性效应变得更加显著，导致电流注入可达DBS类似水平。不能排除在直接电极附近废弃/损坏导线产生的不利影响。系统地识别和探讨了在存在植入物的情况下tES应用的安全相关问题，得出了具体的定量指导原则，并为安全标准奠定了基础。此外，在承认局限性的同时，还提出了几种降低风险的方法（见4.5节）。
