Objective: The objective of this study was to track if/how local field potentials (LFP) change characteristics over the first few days after implantation of a deep brain stimulation (DBS) lead into the subthalamic nucleus (STN).

Background: Current neurostimulation technology can provide therapeutic stimulation and record LFP sensing data. These devices can explore how LFP activity changes under different conditions. This study explored how LFP activity behaves during a 10-day period after a DBS system has been implanted in an animal model.

Method: One sheep was bilaterally implanted in the STN where the left hemisphere was implanted with a segmented DBS lead and the right hemisphere was implanted with a traditional DBS lead (4 ring contacts). Passive sensing was recorded from predetermined bipolar pairs once a day for a 10-day period after the implant surgery. The bipolar pairs were grouped into two categories when collecting data on the segmented lead. Level bipolar pairs refer to when the segmented electrodes are ganged together and act like a ring electrode. Segmented bipolar pairs refer to when bipolar pairs were obtained using the segmented electrodes. Passive sensing was also performed 16-days and 72-days after the implant to obtain more sensing data when tissue had had more time to recover from the surgery.

Results: Overall, the LFP beta power increased over time. When assessing the level bipolar pairs, the ranking of each bipolar pair remained stable over the 10-day monitoring period. When assessing the segmented bipolar pairs, the ranking of each bipolar pair shifted over the 10-day monitoring period. The rankings of the segmented bipolar pairs remained consistent on the 16-day and 72-day monitors, where the LFP power seemed to be located near electrode 2b. During the 1-day monitor, electrode 2b had low beta power compared to other electrodes.

Conclusion: The data shows how sensing close to the surgery may have different results compared to sensing once the brain has been given sufficient time to recover from the surgery, especially when using directional sensing. One possible explanation for the change over time could be related to the stun effect [1,2]. Additionally, a similar trend was observed in nonhuman primates [3]. More studies are required to understand the change in LFP after surgery.

References: [1] Tykocki, Tomasz, et al. “Microlesion effect as a predictor of the effectiveness of subthalamic deep brain stimulation for Parkinson’s disease.” Stereotactic and functional neurosurgery 91.1 (2013): 12-17.
[2] Wang, Yi, et al. “Micro lesion effect of the globus pallidus internus with deep brain stimulation in Parkinson’s disease patients.” Acta Neurochirurgica 159.9 (2017): 1727-1731.
[3] Brinda, AnneMarie K., et al. “Longitudinal analysis of local field potentials recorded from directional deep brain stimulation lead implants in the subthalamic nucleus.” Journal of neural engineering 18.4 (2021): 046050.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/monitoring-local-field-potentials-recorded-after-implant-surgery-from-deep-brain-stimulation-leads-in-the-subthalamic-nucleus-using-a-sheep-animal-model/