Supplementary Material for: Risk of Infection after Deep Brain Stimulation Surgery with Externalization and Local-Field Potential Recordings: Twelve-Year Experience from a Single Institution

Introduction: Deep brain stimulation (DBS) has been an established surgical procedure in the field of functional neurosurgery for many years. The experimental electrophysiological method of local field potential (LFP) recordings in postsurgically externalized patients has made substantial contributions to the better understanding of pathophysiologies underlying movement disorders. As interest in LFP recordings for the development of improved stimulation strategies increases, this study’s aim was to provide evidence concerning safety of this research method, in a major DBS center. Methods: We retrospectively analyzed incidence and infection characteristics in adult patients who underwent two-staged DBS surgery with temporary externalization of leads in our center between January 2008 and November 2019. We focused on whether patients had participated in LFP recordings, and evaluated incidence of infections at 3 months and 1 year after the surgery based on medical records. Infection rates were compared to major DBS studies and reports focusing on the risk of infection due to externalization of DBS leads. Results were visualized using descriptive statistics. Results: Between January 2008 and November 2019, DBS surgery was performed in 528 patients (389/139 patients in the LFP/non-LFP group), mainly for movement disorders such as Parkinson’s disease (308), dystonia (93), and essential tremor (86). Of the patients, 72.9% participated in LFP recordings. The incidence of infections in the acute postsurgical phase (3 months) was 2.46% and did not differ significantly between the LFP group (1.8%) and the non-LFP group (4.32%). The overall incidence after 1 year amounted to 3.6% (19 patients) with no difference between LFP/non-LFP groups. Incidence rates reported in the literature show a large variety (2.6–10%), and the incidence reported here is within the lower range of reported incidences. Discussion/Conclusion: This study demonstrates that DBS is a surgical procedure with a low risk of infection in a large patient cohort. Importantly, it shows that LFP recordings do not have a significant effect on the incidence of infections in patients with externalization. With a representative cohort of more than 380 patients participating in LFP-recordings, this underlines LFP as a safe method in research and supports further use of this method, for example, for the development of adaptive stimulation protocols.引言：脑深部电刺激术（Deep brain stimulation, DBS）多年来已成为功能神经外科领域成熟的外科手术术式。针对术后导线外置患者的局部场电位（local field potential, LFP）记录实验电生理方法，为深入理解运动障碍疾病的病理生理机制做出了重要贡献。随着针对LFP记录以开发更优刺激策略的研究兴趣日益增长，本研究旨在于大型DBS中心中，为该研究方法的安全性提供循证依据。 方法：本研究回顾性分析了2008年1月至2019年11月期间，于本中心接受分期DBS手术且术中临时外置导线的成年患者的感染发生率及感染特征。本研究重点关注患者是否参与LFP记录，并基于病历资料评估术后3个月及1年的感染发生率。将感染发生率与既往聚焦DBS导线外置相关感染风险的主要DBS研究及报告进行对比。研究结果采用描述性统计方法进行可视化呈现。 结果：2008年1月至2019年11月期间，本中心共为528例患者实施DBS手术（局部场电位组389例，非局部场电位组139例），手术适应证主要为运动障碍疾病，包括帕金森病（308例）、肌张力障碍（93例）及特发性震颤（86例）。其中72.9%的患者参与了LFP记录。术后急性期（3个月）的感染发生率为2.46%，局部场电位组（1.8%）与非局部场电位组（4.32%）之间无显著差异。术后1年总体感染发生率为3.6%（共19例患者），两组间仍无显著差异。既往文献报道的感染发生率差异较大（2.6%~10%），本研究的感染发生率处于已报道范围的较低区间。 讨论与结论：本研究证实，针对大样本患者队列实施DBS手术的感染风险较低。尤为重要的是，本研究表明LFP记录并不会对导线外置患者的感染发生率产生显著影响。本研究包含超过380例参与LFP记录的代表性患者队列，这进一步证实了LFP作为研究方法的安全性，并支持该方法在后续研究中的进一步应用，例如用于开发自适应刺激方案。