Marjolein Muller, M. Fiorella Contarino
We greatly appreciated the recent report by Sousa & Tinkhauser (2025),1 which highlighted the issue of cardiac-induced artifacts on local field potentials (LFP) recorded from implantable deep brain stimulation (DBS) systems. Their reported patient with Parkinson's disease (PD), had requested to have the neurostimulator implanted in the left chest to facilitate his right-handed forehand in tennis. The authors demonstrate how these artifacts can affect adaptive stimulation (aDBS) and how they can be identified during in-office recordings. We report here a right-handed gentleman with PD (age around 70), also a tennis player, who underwent bilateral subthalamic nucleus (STN) DBS with SenSight (B33005) leads due to treatment-resistant tremor, and slight bradykinesia and rigidity. The Medtronic Percept™ PC stimulator (Minneapolis, MN) was implanted in the right chest. After a standard monopolar review, stimulation was set on contact points 2 and 10, at 180 Hz, 60us, and 1.7 mA and 0.7 mA, respectively. Initial recordings in the BrainSense™ SetUp mode showed a clear beta peak (17.58 Hz) for the right STN, highest for contact pair 9–11, and a less evident beta peak (19.53 Hz) in the left STN, highest for contact pair 1–3, which were selected for at-home recordings (Fig. 1A,B). No ECG artifacts were detected by online inspection and with the offline Perceive Toolbox (Matlab R2022b).2 About 6 weeks postoperatively, the patient obtained a substantial reduction of tremor, rigidity, and bradykinesia, and improvement of fatigue. This allowed him to resume playing tennis, which he had given up due to his symptoms. Despite reporting no motor fluctuations anymore, on some days but not on others (Fig. 1C–F), chronic recordings showed substantial bilateral increases in the selected beta power, lasting approximately 2–3 hours. When asked, he reported playing tennis during those days and times. We interpret this bilateral increase in beta power as a movement-related artifact, particularly due to the swinging motion of his right forehand movements.3, 4 Our observations add to the considerations reported by Sousa and Tinkhauser,1 showing that while, as previously reported, left-sided implants may be more prone to ECG artifacts,2 right-sided implants could be more likely affected by movement artifacts in right-handed subjects. Movement artifacts resulting in an apparent sustained increase in the beta power, can be mistaken for prolonged off periods, thus erroneously driving overstimulation during aDBS protocols, both in a single-threshold and in a double-threshold mode. These two cases show how one patients' tennis playing, requiring a left-implanted neurostimulator, possibly contributed to the higher ECG contamination, while the other patients' tennis forehand movements produced significant movement artifacts, which altogether, using tennis jargon, could be named a “double fault.” Chronic LFP recordings from implantable DBS systems allow collecting potentially valuable information on disease-related brain activity even in the at-home environment. With the recent introduction of aDBS, many DBS centers worldwide have promptly begun integrating this new feature into clinical practice.5 We consider our practical observations a valuable warning to always approach brain sensing and aDBS critically and never to neglect patients' feedback in the interpretation of the signals. (1) Research project: A. Conception, B. Organization, C. Execution; (2) Statistical Analysis: A. Design, B. Execution, C. Review and Critique; (3) Manuscript Preparation: A. Writing of the first draft, B. Review and Critique. M.M.: 2B, 1B, 1C, 3B. M.F.C.: 1A, 3A, 2A, 2C. Ethical Compliance Statement: The Medical Ethics Committee Leiden The Hague Delft waived the need for an official evaluation. Written informed consent for this publication was obtained from the patient. We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines. Funding Sources and Conflict of Interest: MM and MFC were supported by the European Innovation Council under grant agreement number 101070865 (MINIGRAPH). MFC is an independent consultant for research and educational issues of Medtronic (all fees to institution), is an independent consultant for research by INBRAIN (all fees to institution), provides research support/contracted research for Boston Scientific (all fees to institution) and received speaking fees for: ECMT; and received research support from BostonScientific. Financial Disclosures and Conflict of Interest: The authors declare that there are no additional disclosures to report. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.