Elsevier

Parkinsonism & Related Disorders

Volume 78, September 2020, Pages 124-128
Parkinsonism & Related Disorders

Short communication
Correspondence of optimal stimulation and beta power varies regionally in STN DBS for Parkinson disease

https://doi.org/10.1016/j.parkreldis.2020.08.008Get rights and content

Highlights

  • Beta-oscillations (13–30 Hz) correlate with Parkinsonian motor symptoms.

  • Subthalamic deep brain stimulation treats Parkinsonian motor symptoms.

  • There is debate whether beta oscillations and optimal stimulation co-localize.

  • Co-localization is absent in posterior-lateral and present in posterior-medial STN.

Abstract

Introduction

Subthalamic nucleus deep brain stimulation (STN DBS) for Parkinson disease (PD) normalizes neuronal hypersynchrony in the beta frequency range (13–30 Hz). The spatial correspondence of maximal beta power to the site of optimal stimulation along the DBS lead trajectory has been debated.

Methods

We determined the trajectory locations of the active contact, maximal beta power, and the dorsal border of the STN (DB-STN) in DBS patients. Beta power profiles were measured during intraoperative microelectrode recording (MER). Active contact locations were assigned during blinded, postoperative DBS programming. The DB-STN was identified both electrophysiologically during MER and anatomically on MRI. After grouping DBS trajectories into quadrants relative to the anatomic STN midpoint, we examined regional variations in the relative trajectory locations of the three entities.

Results

STN DBS significantly improved motor performance for all 13 DBS patients, with active contacts at the DB-STN. Along trajectories passing posterior-medial to the STN midpoint, maximal beta power co-localized with active contacts at the DB-STN (difference Δ = 0.4 ± 1.6 mm, p = 0.57). By contrast, in posterior-lateral trajectories, maximal beta arose within the STN, ventral to active contacts (Δ = 1.9 ± 1.3 mm, p = 0.002). For trajectories anterior to the STN midpoint, maximal beta power co-localized with the DB-STN, while active contacts were ventral to peak beta power (p = 0.05).

Conclusion

Our findings indicate that co-localization of optimal stimulation and beta power varies by anatomical region in STN DBS for Parkinson disease.

Introduction

Deep brain stimulation (DBS) in the region of the subthalamic nucleus (STN) alleviates the motor symptoms of medically intractable Parkinson disease (PD). However, the optimal locus of STN DBS remains imprecisely defined. Anatomical studies have identified optimal stimulation loci within the STN, at the dorsal border of the STN (DB-STN), and in the zona incerta above the STN (for review, see Caire et al., 2013 [1]). Other studies have defined the optimal locus of STN DBS electrophysiologically, corresponding to the location of peak beta power of the local field potential (LFP, 13–30Hz) [[2], [3], [4]]. However, peak beta power has been localized not only to the dorsal STN, which corresponds to a proposed region of optimal stimulation [4,5], but also more centrally within the STN, ventral to the expected region of optimal stimulation [6] (for technical discussion, see Marmor et al., 2017 [7]). The objective of this study was to better understand these seemingly conflicting results by measuring the correspondence of maximal beta power and optimal STN DBS in a precise, atlas-independent and fully individualized manner, using high-resolution intraoperative electrophysiology, MRI, and CT imaging. Our hypothesis is that regional variation in the relative lead trajectory locations of the DBS active contact and beta power may explain these conflicting findings.

Section snippets

Study participants

We prospectively studied 13 consecutive subjects with advanced idiopathic PD, undergoing STN DBS surgery at our institution (9 men, 4 women; age, 66 ± 6 years; range, 52–73 years; for selection criteria, see Ref. [8,9]). The study was performed with MEDIRB approval. Each subject provided individual written informed consent.

Target selection and surgical procedure

All subjects underwent validated 3T MR imaging, allowing direct visualization of the STN (MR-visualized STN) [8]. During surgery, an electrophysiologist performed

Results

A total of 26 STN-targeted MER trajectories from 13 PD subjects were initially available for analysis. In 4 of 26 trajectories, the DBS lead was repositioned after microelectrode recording. In an additional 3 of 26 trajectories, large intermittent low-frequency noise artifacts obscured LFP recording. The remaining 19 of 26 trajectories were analyzed for this study.

We observed excellent correspondence between the electrophysiological STN on MER and the MR-visualized STN. The trajectory span of

Discussion

In this study, we quantitatively examine the spatial relationships among the optimal (active) contact, peak beta power along the lead trajectory, and the dorsal border of STN (DB-STN) for patients with PD treated with STN DBS. Unlike previous atlas-based studies, these spatial relationships are defined in an atlas-independent, fully individualized manner, using direct imaging of the STN and DBS contacts and high-resolution intraoperative MER. Our findings, consistent with previous studies,

Authorship

All authors contributed to (1) the conception and design of the study, acquisition of data, and analysis and interpretation of data, (2) drafting the article or revising it critically for important intellectual content, (3) final approval of the submitted manuscript. The authors agree to be accountable for all aspects of the work.

Funding sources

This research was funded by the Taubman Medical Research Institute and the Wallace H. Coulter Foundation. Sponsors had no involvement in study design; in the collection, analysis and interpretation of data; in the writing of the report; or in the decision to submit the article for publication.

Declaration of competing interest

None.

Acknowledgements

We thank Sunjay Dodani for contributions to an earlier version of the manuscript. We thank J. Wayne Aldridge, Kelly J. Lupo, and the members of the STIM program for clinical and technical assistance.

References (12)

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  • Atlas-independent, N-of-1 tissue activation modeling to map optimal regions of subthalamic deep brain stimulation for Parkinson disease

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    Furthermore, stronger HFO activity was found to be specific to patients with tremor-predominant PD (Telkes et al., 2018), which suggests one way that electrophysiological recordings could be incorporated into the N-of-1 VTA modeling approach to further optimize DBS targeting at the individual level (e.g., incorporating HFO power into the optimality measure). Although optimal stimulation sites exhibited high beta activity that was localized in the dorsal STN region (Lu et al., 2020b), it was found that these sites did not co-localize in the posterior-lateral STN region, but did in the posterior-medial STN region (Lu et al., 2020a). More specifically, maximal beta power co-localized with active contacts at the dorsal border of the STN along trajectories passing posterior-medial to the STN midpoint.

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