Awake Deep Brain Stimulation Surgery Research Articles

Utilization of intraoperative Subthalamic Nucleus local field potential recordings to guide postoperative Deep Brain Stimulation programming in Parkinson’s disease (P5-11.013)

<h3>Objective:</h3> To investigate whether intraoperative recordings of subthalamic nucleus (STN) local field potentials (LFPs) during awake deep brain stimulation (DBS) surgery for Parkinson’s disease can provide valuable information for postoperative DBS programming. <h3>Background:</h3> DBS is a well-established treatment of Parkinson’s disease. Intraoperative LFP recordings during awake DBS surgery are used to confirm accurate targeting. Postoperative DBS programming is usually based on clinical response. It is unclear whether the intraoperative LFP recordings can guide postoperative DBS programming. <h3>Design/Methods:</h3> All patients with Parkinson’s disease who had awake placement of STN DBS electrodes with intraoperative STN LFP recordings (Alpha Omega LeadConfirm®) at the University of Utah since August 2021 were identified. The peak beta band power for each individual electrode contact was identified. For directional electrodes, the LFP beta peaks were averaged across the three directional contacts for each level. Postoperatively the DBS systems were programmed based on symptom response. The activated DBS levels were compared to the levels with the highest and lowest LFP beta band peaks. <h3>Results:</h3> 13 DBS STN electrodes, from 8 patients (all males, mean age=60±10 years, mean UPDRS score=40±14) were analyzed. The grand average peak beta band frequency was 21Hz with power of 2.3. In 2 out of 13 electrodes the level with the highest beta band peak was activated postoperatively. In 8 electrodes the active levels and the levels with the highest peaks were adjacent. In one electrode the contact with the highest peaks provided best benefit but the contact with the lowest beta peak was activated to avoid dyskinesias. <h3>Conclusions:</h3> In the majority of the electrodes (11 out of 13 electrodes) the levels that were post-operatively activated based on best clinical response coincided or were adjacent to the levels with the highest intraoperative STN LFP beta power peaks. The intraoperative LFP recordings can potentially provide valuable information for programming guidance postoperatively. <b>Disclosure:</b> An immediate family member of Dr. Anwer has received personal compensation for serving as an employee of Southwest Airlines. Dr. Anwer has stock in Boeing. Mr. PAXTON has nothing to disclose. Dr. Rahimpour has nothing to disclose. Dr. Alshaikh has nothing to disclose. D. James Ballard has nothing to disclose. Dr. Steffens has nothing to disclose. Ms. Zorn has nothing to disclose. Dr. Kassavetis has nothing to disclose.

152 Caudate and Dorsolateral Prefrontal Cortex Beta Bursts During Working Memory Encoding Correlate with Memory Impairment in Parkinson’s Disease

INTRODUCTION: Cognitive dysfunction is a common nonmotor symptom of Parkinson’s disease (PD), with memory impairment being a primary cause of disability. Decreased dopamine in PD elevates beta power in cortico-striato-thalamo-cortico (CSTC) motor circuits and is the basis of closed-loop deep brain stimulation (DBS) strategies. Analogous dysfunction of parallel CSTC cognitive circuitry including caudate and dorsolateral prefrontal cortex (DLPFC) may mediate PD cognitive impairment and be a neuromodulation target for cognitive symptoms. We have previously shown caudate and DLPFC beta power contributes to working memory updating, and suppression of prefrontal cortex beta bursts during working memory encoding has been linked with improved performance. However, how PD affects beta bursting in relation to memory function remains unknown. METHODS: Fourteen PD patients undergoing awake DBS surgery with electrode trajectories traversing the caudate, DLPFC, or both participated in this study. Subjects completed a 2-back working memory task where they identified whether a presented word matched the word presented two trials prior. Bursts were defined as epochs where power exceeded a Z-score of two for at least three oscillatory cycles. We correlated change in caudate and DLPFC beta burst rates during working memory encoding with subjects’ composite memory scores, which were calculated from preoperative neuropsychological assessments. RESULTS: Caudate and DLPFC beta burst rates decreased significantly during working memory encoding for correct trials. In both structures, change in beta burst rate was significantly correlated with subjects’ composite memory scores, with greater decreases in beta bursting corresponding with better memory function. CONCLUSIONS: Beta bursts are suppressed in caudate and DLPFC during working memory encoding. Reduced beta burst suppression during encoding correlated with greater memory impairment in PD patients, indicating that altered caudate and DLPFC beta bursting dynamics may contribute to PD memory impairment.

Quantifying neuro-motor correlations during awake deep brain stimulation surgery using markerless tracking

The expanding application of deep brain stimulation (DBS) therapy both drives and is informed by our growing understanding of disease pathophysiology and innovations in neurosurgical care. Neurophysiological targeting, a mainstay for identifying optimal, motor responsive targets, has remained largely unchanged for decades. Utilizing deep learning-based computer vision and related computational methods, we developed an effective and simple intraoperative approach to objectively correlate neural signals with movements, automating and standardizing the otherwise manual and subjective process of identifying ideal DBS electrode placements. Kinematics are extracted from video recordings of intraoperative motor testing using a trained deep neural network and compared to multi-unit activity recorded from the subthalamic nucleus. Neuro-motor correlations were quantified using dynamic time warping with the strength of a given comparison measured by comparing against a null distribution composed of related neuro-motor correlations. This objective measure was then compared to clinical determinations as recorded in surgical case notes. In seven DBS cases for treatment of Parkinson’s disease, 100 distinct motor testing epochs were extracted for which clear clinical determinations were made. Neuro-motor correlations derived by our automated system compared favorably with expert clinical decision making in post-hoc comparisons, although follow-up studies are necessary to determine if improved correlation detection leads to improved outcomes. By improving the classification of neuro-motor relationships, the automated system we have developed will enable clinicians to maximize the therapeutic impact of DBS while also providing avenues for improving continued care of treated patients.

Commentary: Awake Deep Brain Stimulation Surgery Without Intraoperative Imaging Is Accurate and Effective: A Case Series.

*Harquail Centre for Neuromodulation, Sunnybrook Health Sciences Centre, Sunnybrook Research Institute, Toronto, Ontario, Canada; ‡Hurvitz Brain Sciences Centre, Sunnybrook Research Institute, Toronto, Ontario, Canada; §Division of Neurosurgery, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada Correspondence: Clement Hamani, MD, PhD, Hurvitz Brain Sciences Centre, Sunnybrook Research Institute, 2075 Bayview Av, S126, Toronto, ONM4N3M5, Canada. Email: [email protected]

Commentary: Awake Deep Brain Stimulation Surgery Without Intraoperative Imaging is Accurate and Effective: A Case Series.

Loma Linda University School of Medicine, Loma Linda, California, USA Correspondence: Miguel Angel Lopez-Gonzalez, MD, Department of Neurosurgery, Loma Linda University School of Medicine, 11234 Anderson St., Loma Linda, CA92354, USA. Email: [email protected]

Frameless Robot-Assisted vs Frame-Based Awake Deep Brain Stimulation Surgery: An Evaluation of Technique and New Challenges.

Methodological approaches to deep brain stimulation (DBS) continue to evolve from awake frame-based to asleep frameless procedures with robotic assistance, primarily directed to optimize operative efficiency, lead accuracy, and patient comfort. Comparison between the 2 is scarce. To analyze the impacts of methodological differences on operative efficiency and stereotactic accuracy using a frame compared with a frameless robotic platform while maintaining the awake state and use of multiple microelectrode recording (MER) trajectories. Thirty-four consecutive patients who underwent bilateral awake frameless robot-assisted DBS were compared with a previous cohort of 30 patients who underwent frame-based surgery. Patient demographics, operative times, and MER data were collected for both cohorts. Two-dimensional radial errors of lead placements were calculated. Preoperative setup, surgical, and total operating room times were all significantly greater for the robot-assisted cohort (P < .001). The need for computed tomography imaging when referencing the robotic fiducials led to increased setup duration because of patient transport, unnecessary for the frame-based cohort. Multiple simultaneous MER trajectories increased surgical time (mean 26 min) for the robot-assisted cohort only. The mean radial errors in the robot-assisted and frame cohorts were 0.98 ± 0.66 and 0.74 ± 0.49 mm (P = .03), respectively. The use of a truly frameless robotic platform such as the Mazor Renaissance (Mazor Robotics Ltd) presented challenges when implementing techniques used during awake frame-based surgery. Maintaining good accuracy, intraoperative reference imaging, and limited MER trajectories will help integrate frameless robot assistance into the awake DBS surgical workflow.

Rapid motor fluctuations reveal short-timescale neurophysiological biomarkers of Parkinson’s disease

Objective. Identifying neural activity biomarkers of brain disease is essential to provide objective estimates of disease burden, obtain reliable feedback regarding therapeutic efficacy, and potentially to serve as a source of control for closed-loop neuromodulation. In Parkinson’s disease (PD), microelectrode recordings (MER) are routinely performed in the basal ganglia to guide electrode implantation for deep brain stimulation (DBS). While pathologically-excessive oscillatory activity has been observed and linked to PD motor dysfunction broadly, the extent to which these signals provide quantitative information about disease expression and fluctuations, particularly at short timescales, is unknown. Furthermore, the degree to which informative signal features are similar or different across patients has not been rigorously investigated. We sought to determine the extent to which motor error in PD across patients can be decoded on a rapid timescale using spectral features of neural activity. Approach. Here, we recorded neural activity from the subthalamic nucleus (STN) of subjects with PD undergoing awake DBS surgery while they performed an objective, continuous behavioral assessment that synthesized heterogenous PD motor manifestations to generate a scalar measure of motor dysfunction at short timescales. We then leveraged natural motor performance variations as a ‘ground truth’ to identify corresponding neurophysiological biomarkers. Main results. Support vector machines using multi-spectral decoding of neural signals from the STN succeeded in tracking the degree of motor impairment at short timescales (as short as one second). Spectral power across a wide range of frequencies, beyond the classic ‘β’ oscillations, contributed to this decoding, and multi-spectral models consistently outperformed those generated using more isolated frequency bands. While generalized decoding models derived across subjects were able to estimate motor impairment, patient-specific models typically performed better. Significance. These results demonstrate that quantitative information about short-timescale PD motor dysfunction is available in STN neural activity, distributed across various patient-specific spectral components, such that an individualized approach will be critical to fully harness this information for optimal disease tracking and closed-loop neuromodulation.

Better Hemodynamics and Less Antihypertensive Medication: Comparison of Scalp Block and Local Infiltration Anesthesia for Skull-Pin Placement in Awake Deep Brain Stimulation Surgery

In deep brain stimulation (DBS) surgery, acute high blood pressure (BP) is a risk factor for intracranial hemorrhage. To minimize pain and hypertensive conditions, sufficient local anesthesia is mandatory. We evaluated whether local instillation of anesthetics (LA) or a scalp block (SB) is superior concerning intraoperative hemodynamics and analgesia. We retrospectively analyzed intraoperative cardiovascular parameters and perioperative medication in 47 patients (LA= 29, SB= 18) undergoing DBS surgery. Primary study end points were intraoperative systolic BP and heart rate. Secondary end points were use of intraoperative antihypertensives and perioperative analgesics. Patients who had SB showed lower mean systolic BP and heart rate compared with patients who had LA. Patients who had LA required more antihypertensive medication to stabilize BP. BP was higher, particularly during the first 90 minutes of surgery, in patients who had LA. Thereafter, more antihypertensives were necessary to achieve sufficient BP control in the LA group. The dose of analgesics did not differ significantly between both groups during and after surgery. Our data suggest that SB might be superior to LA for DBS surgery with respect to BP control and hemodynamics. The need for analgesics does not differ substantially between both anesthetic treatment options.

EP 62. Motor evoked potentials mapping improves detection of capsular side effects during deep brain stimulation

Introduction One of the main reasons to perform deep brain stimulation (DBS) on awake patient is detection of activation of descending capsular motor pathways as they represent therapy-limiting side effect. Current technique of capsular activation detection is based on visual detection of muscular contraction during stimulation with standard “tonic” DBS stimulation parameters. Intraoperative mapping of subcortical motor evoked potentials (MEP) during DBS surgery, as already shown in the literature, is feasible and time-efficient, also in patients under general anesthesia. We investigate value of motor evoked potentials mapping in basal ganglia as alternative measurement of safe therapeutic window in stimulation parameters. Methods This study includes recording data of 7 Patients, undergoing awake DBS surgery in subthalamic nucleus or in thalamus and of 1 DBS patient under general anesthesia. Recording data of 16 trajectories and 32 stimulation sites was available. Anodal stimulation was applied in stereotactic target on the macroelectrode tip (microTargeting electrodes, FHC, USA) using train-of-five technique in 1 mA steps 0–5 mA. Recordings were obtained using skin surface electrodes on projection of m. mentalis, m. abductor pollicis brevis, m. flexor digitorum, m. tibialis anterior on contralateral to stimulation side. Visual detection of motor contraction under 130 Hz 60 μs stimulation in 1 mA steps (0–5 mA) was used as standard control parameter. Results MEP recordings were successful in all stimulation sites. MEP threshold current correlated with current values of 130 Hz stimulation, which caused visually detectable muscle contractions and with postoperative DBS side effect thresholds. Detection of muscle response activation was very sensitive and muscle-specific and remained stable under repeated stimulation. Patients described very little or no discomfort during MEP mapping, significantly lower comparing to classical 130 Hz stimulation on motor-threshold. MEP threshold detection was easily obtainable under propofol-remifentanyl general anesthesia and had same current values as “tonic” stimulation postoperatively. Conclusions MEP mapping in basal ganglia is safe and feasible alternative to standard motor side-effect detection, which can improve safety and comfort of DBS procedure. MEP motor threshold correlates well to capsular activation with standard DBS parameters and can be obtained under general anesthesia.

Awake Neurophysiologically Guided versus Asleep MRI-Guided STN DBS for Parkinson Disease: A Comparison of Outcomes Using Levodopa Equivalents

Background: Deep brain stimulation (DBS) for Parkinson's disease (PD) has traditionally been performed in awake patients. Some patients are unable to tolerate awake surgery or extensive time off their medication to allow for neurophysiological testing during traditional DBS implantation, which has previously limited surgical options for these patients. Recently, asleep image-guided lead placement using intraoperative MRI or CT for verification has been proposed as an alternative for patients unable or unwilling to undergo awake DBS surgery. Methods: We conducted a retrospective chart review comparing PD patients who underwent asleep MRI-guided subthalamic nucleus (STN) DBS lead placement (n = 14) and awake neurophysiologically guided STN DBS lead placement (n = 23) at our institution. Both groups' levodopa equivalent daily doses (LEDDs) and complications at approximately 6 months of follow-up were compared, along with operative times. Results: Both groups showed statistically similar reductions in LEDD at 6 months of therapy (38.27% for awake, 49.27% for asleep; p = 0.4447), and similar complications. Operative times were initially longer for MRI-guided DBS but improved with surgical experience. Conclusion: Asleep MRI-guided DBS is a viable option for PD patients unable or unwilling to undergo awake placement, with similar results in terms of LEDD reduction and complications.