Subthalamic nucleus deep brain stimulator placement using high-field interventional magnetic resonance imaging and a skull-mounted aiming device: technique and application accuracy

Efficacy and safety of robot-assisted deep brain stimulation for Parkinson's disease: a meta-analysis

Objective

This meta-analysis aims to assess the effectiveness and safety of robot-assisted deep brain stimulation (DBS) surgery for Parkinson's disease(PD).

Methods

Four databases (Medline, Embase, Web of Science and CENTRAL) were searched from establishment of database to 23 March 2024, for articles studying robot-assisted DBS in patients diagnosed with PD. Meta-analyses of vector error, complication rate, levodopa-equivalent daily dose (LEDD), Unified Parkinson's Disease Rating Scale (UPDRS), UPDRS II, UPDRS III, and UPDRS IV were performed.

Results

A total of 15 studies were included in this meta-analysis, comprising 732 patients with PD who received robot-assisted DBS. The pooled results revealed that the vector error was measured at 1.09 mm (95% CI: 0.87 to 1.30) in patients with Parkinson's disease who received robot-assisted DBS. The complication rate was 0.12 (95% CI, 0.03 to 0.24). The reduction in LEDD was 422.31 mg (95% CI: 68.69 to 775.94). The improvement in UPDRS, UPDRS III, and UPDRS IV was 27.36 (95% CI: 8.57 to 46.15), 14.09 (95% CI: 4.67 to 23.52), and 3.54 (95% CI: -2.35 to 9.43), respectively.

Conclusion

Robot-assisted DBS is a reliable and safe approach for treating PD. Robot-assisted DBS provides enhanced accuracy in contrast to conventional frame-based stereotactic techniques. Nevertheless, further investigation is necessary to validate the advantages of robot-assisted DBS in terms of enhancing motor function and decreasing the need for antiparkinsonian medications, in comparison to traditional frame-based stereotactic techniques.Clinical trial registration: PROSPERO(CRD42024529976).

Towards MR-Guided Robotic Intracerebral Hemorrhage Evacuation: Aiming Device Design and ex vivo Ovine Head Trial

Stereotactic neurosurgery is a well-established surgical technique for navigation and guidance during treatment of intracranial pathologies. Intracerebral hemorrhage (ICH) is an example of various neurosurgical conditions that can benefit from stereotactic neurosurgery. As a part of our ongoing work toward real-time MR-guided ICH evacuation, we aim to address an unmet clinical need for a skull-mounted frameless stereotactic aiming device that can be used with minimally invasive robotic systems for MR-guided interventions. In this paper, we present NICE-Aiming, a Neurosurgical, Interventional, Configurable device for Effective-Aiming in MR-guided robotic neurosurgical interventions. A kinematic model was developed and the system was used with a concentric tube robot (CTR) for ICH evacuation in (i) a skull phantom and (ii) in the first ever reported ex vivo CTR ICH evacuation using an ex vivo ovine head. The NICE-Aiming prototype provided a tip accuracy of 1.41±0.35 mm in free-space. In the MR-guided gel phantom experiment, the targeting accuracy was 2.07±0.42 mm and the residual hematoma volume was 12.87 mL (24.32% of the original volume). In the MR-guided ex vivo ovine head experiment, the targeting accuracy was 2.48±0.48 mm and the residual hematoma volume was 1.42 mL (25.08% of the original volume).

Interactive Multi-Stage Robotic Positioner for Intra-Operative MRI-Guided Stereotactic Neurosurgery

Magnetic resonance imaging (MRI) demonstrates clear advantages over other imaging modalities in neurosurgery with its ability to delineate critical neurovascular structures and cancerous tissue in high-resolution 3D anatomical roadmaps. However, its application has been limited to interventions performed based on static pre/post-operative imaging, where errors accrue from stereotactic frame setup, image registration, and brain shift. To leverage the powerful intra-operative functions of MRI, e.g., instrument tracking, monitoring of physiological changes and tissue temperature in MRI-guided bilateral stereotactic neurosurgery, a multi-stage robotic positioner is proposed. The system positions cannula/needle instruments using a lightweight (203 g) and compact (Ø97 × 81 mm) skull-mounted structure that fits within most standard imaging head coils. With optimized design in soft robotics, the system operates in two stages: i) manual coarse adjustment performed interactively by the surgeon (workspace of ±30°), ii) automatic fine adjustment with precise (<0.2° orientation error), responsive (1.4 Hz bandwidth), and high-resolution (0.058°) soft robotic positioning. Orientation locking provides sufficient transmission stiffness (4.07 N/mm) for instrument advancement. The system's clinical workflow and accuracy is validated with lab-based (<0.8 mm) and MRI-based testing on skull phantoms (<1.7 mm) and a cadaver subject (<2.2 mm). Custom-made wireless omni-directional tracking markers facilitated robot registration under MRI.

Comparison of intraoperative imaging guided versus microelectrode recording guided deep brain stimulation for Parkinson's disease: A meta-analysis

BACKGROUND

Traditionally, most centers would use microelectrode recording (MER) to refine targeting in deep brain stimulation (DBS) surgery. In recent years, intraoperative imaging (IMG) guided DBS has become an alternative way to verify lead placement. Currently, there is still controversy surrounding the necessity of MER or IMG for DBS. This meta-analysis aims to explore lead accuracy, clinical efficacy and safety between IMG and MER guided DBS for Parkinson's disease (PD).

METHODS

PubMed, Embase, Web of Science, Cochrane Library were searched up to Mar, 2021 for studies reporting comparisons between IMG and MER guided DBS for PD. Subgroup analysis was conducted to assess effects of different IMG technology and DBS targeting site.

RESULTS

Six studies, comprising of 478 patients were included in our analysis. The mean difference between the two implantation techniques in stereotactic accuracy, lead passes per trajectory, improvement% of Unified Parkinson's Disease Rating Scale part III and levodopa equivalent daily dose were -0.45 (95% confidence interval, CI=-1.11 to 0.20), -0.18 (95% CI=-0.41 to 0.06), 3.40 (95% CI=-5.36 to 12.16), and 5.00 (95% CI=-1.40 to 11.39), respectively. No significant differences were observed in each adverse event and operation/procedure time between the two implantation techniques.

CONCLUSIONS

Both IMG and MER guided DBS offered effective control of motor symptoms for PD. Besides, IMG guided is comparable to MER guided DBS, in terms of safety, accuracy and efficiency. It is recommended for each hospital to select DBS guidance technology based on available resources and equipment.

Surgical treatment methods in the course of psychiatric disorders: Deep brain stimulation-Novel insights and indications

Deep brain stimulation (DBS) is a relatively dated treatment procedure that emerged in the late 1980s. Nonetheless, numerous studies are being carried out to examine its influence on the human brain and develop new treatment indications. This systematic review aims to summarize the current state of knowledge referring to DBS, investigate novel insights into its indications, and discuss the technical aspects and rationale behind DBS application. In particular, we sought to subject to scrutiny the application of DBS specifically in anorexia nervosa (AN), various addiction types, depression, and obsessive-compulsive disorders (OCDs). The method is supposed to offer promising results, especially in pharmacologically resistant forms of the upper-mentioned psychiatric disorders. Moreover, further insight has been provided into the historical notions of the method and differences in the surgical approach in specific disease entities. Furthermore, we mark the possible influence of comorbidities on treatment results. Our review consists of articles and studies found on PubMed, Google Scholar, Cochrane, and Scopus, which were then analyzed with scrutiny in the identification process, including the most resourceful ones. After methodological quality and risk of bias assessment, a total of 53 studies were included. To this date, DBS's usefulness in the treatment of AN, OCDs, depression, and addictions has been proven, despite an ongoing debate concerning the technical aspects and parameters when applying DBS. To the best of our knowledge, we have not found any paper that would recapitulate the current state of DBS in the context of psychiatric disorders with an addition of technical insights.

Accurate Deep Brain Stimulation Lead Placement Concurrent With Research Electrocorticography

BACKGROUND

Using electrocorticography for research (R-ECoG) during deep brain stimulation (DBS) surgery has advanced our understanding of human cortical-basal ganglia neurophysiology and mechanisms of therapeutic circuit modulation. The safety of R-ECoG has been established, but potential effects of temporary ECoG strip placement on targeting accuracy have not been reported.

OBJECTIVE

To determine whether temporary subdural electrode strip placement during DBS implantation surgery affects lead implantation accuracy.

METHODS

Twenty-four consecutive patients enrolled in a prospective database who underwent awake DBS surgery were identified. Ten of 24 subjects participated in R-ECoG. Lead locations were determined after fusing postoperative computed tomography scans into the surgical planning software. The effect of brain shift was quantified using Lead-DBS and analyzed in a mixed-effects model controlling for time interval to postoperative computed tomography. Targeting accuracy was reported as radial and Euclidean distance errors and compared with Mann-Whitney tests.

RESULTS

Neither radial error nor Euclidean distance error differed significantly between R-ECoG participants and nonparticipants. Pneumocephalus volume did not differ between the 2 groups, but brain shift was slightly greater with R-ECoG. Pneumocephalus volume correlated with brain shift, but neither of these measures significantly correlated with Euclidean distance error. There were no complications in either group.

CONCLUSION

In addition to an excellent general safety profile as has been reported previously, these results suggest that performing R-ECoG during DBS implantation surgery does not affect the accuracy of lead placement.

Artificial Intelligence for Neurosurgery : Current State and Future Directions

Artificial intelligence (AI) is a field of computer science that equips machines with human-like intelligence and enables them to learn, reason, and solve problems when presented with data in various formats. Neurosurgery is often at the forefront of innovative and disruptive technologies, which have similarly altered the course of acute and chronic diseases. In diagnostic imaging, such as X-rays, computed tomography, and magnetic resonance imaging, AI is used to analyze images. The use of robots in the field of neurosurgery is also increasing. In neurointensive care units, AI is used to analyze data and provide care to critically ill patients. Moreover, AI can be used to predict a patient's prognosis. Several AI applications have already been introduced in the field of neurosurgery, and many more are expected in the near future. Ultimately, it is our responsibility to keep pace with this evolution to provide meaningful outcomes and personalize each patient's care. Rather than blindly relying on AI in the future, neurosurgeons should gain a thorough understanding of it and use it to enhance their patient care.

STN-DBS electrode placement accuracy and motor improvement in Parkinson's disease: systematic review and individual patient meta-analysis

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective neurosurgical treatment for Parkinson's disease. Surgical accuracy is a critical determinant to achieve an adequate DBS effect on motor performance. A two-millimetre surgical accuracy is commonly accepted, but scientific evidence is lacking. A systematic review and meta-analysis of study-level and individual patient data (IPD) was performed by a comprehensive search in MEDLINE, EMBASE and Cochrane Library. Primary outcome measures were (1) radial error between the implanted electrode and target; (2) DBS motor improvement on the Unified Parkinson's Disease Rating Scale part III (motor examination). On a study level, meta-regression analysis was performed. Also, publication bias was assessed. For IPD meta-analysis, a linear mixed effects model was used. Forty studies (1391 patients) were included, reporting radial errors of 0.45-1.86 mm. Errors within this range did not significantly influence the DBS effect on motor improvement. Additional IPD analysis (206 patients) revealed that a mean radial error of 1.13±0.75 mm did not significantly change the extent of DBS motor improvement. Our meta-analysis showed a huge publication bias on accuracy data in DBS. Therefore, the current literature does not provide an unequivocal upper threshold for acceptable accuracy of STN-DBS surgery. Based on the current literature, DBS-electrodes placed within a 2 mm range of the intended target do not have to be repositioned to enhance motor improvement after STN-DBS for Parkinson's disease. However, an indisputable upper cut-off value for surgical accuracy remains to be established. PROSPERO registration number is CRD42018089539.

Advances, technological innovations, and future prospects in stereotactic brain biopsies

Stereotactic brain biopsy is one of the most frequently performed brain surgeries. This review aimed to expose the latest cutting-edge and updated technologies and innovations available to neurosurgeons to safely perform stereotactic brain biopsy by minimizing the risks of complications and ensuring that the procedure is successful, leading to a histological diagnosis. We also examined methods for improving preoperative, intraoperative, and postoperative workflows. We performed a comprehensive state-of-the-art literature review. Intraoperative histology, fluorescence, and imaging techniques appear as smart tools to improve the diagnostic yield of biopsy. Constant innovations such as optical methods and augmented reality are also being made to increase patient safety. Robotics and integrated imaging techniques provide an enhanced intraoperative workflow. Patients' management algorithms based on early discharge after biopsy optimize the patient's personal experience and make the most efficient possible use of the available hospital resources. Many new trends are emerging, constantly improving patient care and safety, as well as surgical workflow. A parameter that must be considered is the cost-effectiveness of these devices and the possibility of using them on a daily basis. The decision to implement a new instrument in the surgical workflow should also be dependent on the number of procedures per year, the existing stereotactic equipment, and the experience of each center. Research on patients' postbiopsy management is another mandatory approach to enhance the safety profile of stereotactic brain biopsy and patient satisfaction, as well as to reduce healthcare costs.

Application of the robot-assisted implantation in deep brain stimulation

INTRODUCTION

This work aims to assess the accuracy of robotic assistance guided by a videometric tracker in deep brain stimulation (DBS).

METHODS

We retrospectively reviewed a total of 30 DBS electrode implantations, assisted by the Remebot robotic system, with a novel frameless videometric registration workflow. Then we selected 30 PD patients who used stereotactic frame surgery to implant electrodes during the same period. For each electrode, accuracy was assessed using radial and axial error.

RESULTS

The average radial error of the robot-assisted electrode implantation was 1.28 ± 0.36 mm, and the average axial error was 1.20 ± 0.40 mm. No deaths or associated hemorrhages, infections or poor incision healing occurred.

CONCLUSION

Robot-assisted implantation guided by a videometric tracker is accurate and safe.

Targeting Accuracy and Clinical Outcomes of Awake Vs Asleep Interventional MRI-Guided Deep Brain Stimulation for Parkinson's Disease: The UCSF Experience

BACKGROUND

Interventional MRI (iMRI)-guided implantation of deep brain stimulator (DBS) leads has been developed to treat patients with Parkinson's disease (PD) without the need for awake testing.

OBJECTIVE

Direct comparisons of targeting accuracy and clinical outcomes for awake stereotactic with asleep iMRI-DBS for PD are limited.

METHODS

We performed a retrospective review of patients with PD who underwent awake or iMRI-guided DBS surgery targeting the subthalamic nucleus or globus pallidus interna between 2013 and 2019 at our institution. Outcome measures included Unified Parkinson's Disease Rating Scale Part III scores, levodopa equivalent daily dose, radial error between intended and actual lead locations, stimulation parameters, and complications.

RESULTS

Of the 218 patients included in the study, the iMRI cohort had smaller radial errors (iMRI: 1.27 ± 0.72 mm, awake: 1.59 ± 0.96 mm, P < .01) and fewer lead passes (iMRI: 1.0 ± 0.16, awake: 1.2 ± 0.41, P < .01). Changes in Unified Parkinson's Disease Rating Scale were similar between modalities, but awake cases had a greater reduction in levodopa equivalent daily dose than iMRI cases (P < .01), which was attributed to the greater number of awake subthalamic nucleus cases on multivariate analysis. Effective clinical contacts used for stimulation, side effect thresholds, and complication rates were similar between modalities.

CONCLUSION

Although iMRI-DBS may result in more accurate lead placement for intended target compared with awake-DBS, clinical outcomes were similar between surgical approaches. Ultimately, patient preference and surgeon experience with a given DBS technique should be the main factors when determining the "best" method for DBS implantation.

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

BACKGROUND

The success of deep brain stimulation (DBS) surgery depends on the accuracy of electrode placement. Several factors can affect this such as brain shift, the quality of preoperative planning, and technical factors. It is crucial to determine whether techniques yield accurate lead placement and effective symptom relief. Many of the studies establishing the accuracy of frameless techniques used intraoperative imaging to further refine lead placement.

OBJECTIVE

To determine whether awake lead placement without intraoperative imaging can achieve similar minimal targeting error while preserving clinical results.

METHODS

Eighty-two trajectories in 47 patients who underwent awake, frameless DBS lead placement with the Fred Haer Corporation STarFix system for essential tremor or Parkinson's disease were analyzed. Neurological testing during lead placement was used to determine appropriate lead locations, and no intraoperative imaging was performed. Accuracy data were compared with previously performed studies.

RESULTS

The Euclidean error for the patient cohort was 1.79 ± 1.02 mm, and the Pythagorean error was 1.40 ± 0.95 mm. The percentage symptom improvement evaluated by the Unified Parkinson's Disease Rating Scale for Parkinson's disease or the Fahn-Tolosa-Marin scale for essential tremor was similar to reported values at 58% ± 17.2% and 67.4% ± 24.7%, respectively. The operative time was 95.0 ± 30.3 minutes for all study patients.

CONCLUSION

Awake, frameless DBS surgery with the Fred Haer Corporation STarFix system does not require intraoperative imaging for stereotactic accuracy or clinical effectiveness.

Stability and Effect of Parkinsonian State on Deep Brain Stimulation Cortical Evoked Potentials

OBJECTIVES

To characterize and compare the stability of cortical potentials evoked by deep brain stimulation (DBS) of the subthalamic nucleus (STN) across the naïve, parkinsonian, and pharmacologically treated parkinsonian states. To advance cortical potentials as possible biomarkers for DBS programming.

MATERIALS AND METHODS

Serial electrocorticographic (ECoG) recordings were made more than nine months from a single non-human primate instrumented with bilateral ECoG grids spanning anterior parietal to prefrontal cortex. Cortical evoked potentials (CEPs) were generated through time-lock averaging of the ECoG recordings to DBS pulses delivered unilaterally in the STN region using a chronically implanted, six-contact, scaled DBS lead. Recordings were made across the naïve followed by mild and moderate parkinsonian conditions achieved by staged injections of the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) neurotoxin. In addition to characterizing the spatial distribution and stability of the response within each state, changes in the amplitude and latency of CEP components as well as in the frequency content were examined in relation to parkinsonian severity and dopamine replacement.

RESULTS

In the naïve state, the STN DBS CEP presented as a multiphase response maximal over M1 cortex, with components attributable to physiological activity distinguishable from stimulus artifact as early as 0.45-0.75 msec poststimulation. When delivered using therapeutically effective parameters in the parkinsonian state, the CEP was highly stable across multiple recording sessions within each behavioral state. Across states, significant differences were present with respect to both the latency and amplitude of individual response components, with greater differences present for longer-latency components (all p < 0.05). Power spectral density analysis revealed a high-beta peak within the evoked response, with significant changes in power between disease states across multiple frequency bands.

CONCLUSIONS

Our findings underscore the spatiotemporal specificity and relative stability of the DBS-CEP associated with different disease states and with therapeutic benefit. DBS-CEP may be a viable biomarker for therapeutic programming.

Electrically evoked and spontaneous neural activity in the subthalamic nucleus under general anesthesia

OBJECTIVE

Deep brain stimulation (DBS) surgery is commonly performed with the patient awake to facilitate assessments of electrode positioning. However, awake neurosurgery can be a barrier to patients receiving DBS. Electrode implantation can be performed with the patient under general anesthesia (GA) using intraoperative imaging, although such techniques are not widely available. Electrophysiological features can also aid in the identification of target neural regions and provide functional evidence of electrode placement. Here we assess the presence and positional variation under GA of spontaneous beta and high-frequency oscillation (HFO) activity, and evoked resonant neural activity (ERNA), a novel evoked response localized to the subthalamic nucleus.

METHODS

ERNA, beta, and HFO were intraoperatively recorded from DBS leads comprising four individual electrodes immediately after bilateral awake implantation into the subthalamic nucleus of 21 patients with Parkinson's disease (42 hemispheres) and after subsequent GA induction deep enough to perform pulse generator implantation. The main anesthetic agent was either propofol (10 patients) or sevoflurane (11 patients).

RESULTS

GA reduced the amplitude of ERNA, beta, and HFO activity (p < 0.001); however, ERNA amplitudes remained large in comparison to spontaneous local field potentials. Notably, a moderately strong correlation between awake ERNA amplitude and electrode distance to an "ideal" therapeutic target within dorsal STN was preserved under GA (awake: ρ = -0.73, adjusted p value [padj] < 0.001; GA: ρ = -0.69, padj < 0.001). In contrast, correlations were diminished under GA for beta (awake: ρ = -0.45, padj < 0.001; GA: ρ = -0.13, padj = 0.12) and HFO (awake: ρ = -0.69, padj < 0.001; GA: ρ = -0.33, padj < 0.001). The largest ERNA occurred at the same electrode (awake vs GA) for 35/42 hemispheres (83.3%) and corresponded closely to the electrode selected by the clinician for chronic therapy at 12 months (awake ERNA 77.5%, GA ERNA 82.5%). The largest beta amplitude occurred at the same electrode (awake vs GA) for only 17/42 (40.5%) hemispheres and 21/42 (50%) for HFO. The electrode measuring the largest awake beta and HFO amplitudes corresponded to the electrode selected by the clinician for chronic therapy at 12 months in 60% and 70% of hemispheres, respectively. However, this correspondence diminished substantially under GA (beta 20%, HFO 35%).

CONCLUSIONS

ERNA is a robust electrophysiological signal localized to the dorsal subthalamic nucleus subregion that is largely preserved under GA, indicating it could feasibly guide electrode implantation, either alone or in complementary use with existing methods.

Deep brain stimulation for Parkinson’s Disease: A Review and Future Outlook

Parkinson's Disease (PD) is a neurodegenerative disorder that manifests as an impairment of motor and non-motor abilities due to a loss of dopamine input to deep brain structures. While there is presently no cure for PD, a variety of pharmacological and surgical therapeutic interventions have been developed to manage PD symptoms. This review explores the past, present and future outlooks of PD treatment, with particular attention paid to deep brain stimulation (DBS), the surgical procedure to deliver DBS, and its limitations. Finally, our group's efforts with respect to brain mapping for DBS targeting will be discussed.

The future perspectives of psychiatric neurosurgery

The future of psychiatric neurosurgery can be viewed from two separate perspectives: the immediate future and the distant future. Both show promise, but the treatment strategy for mental diseases and the technology utilized during these separate periods will likely differ dramatically. It can be expected that the initial advancements will be built upon progress of neuroimaging and stereotactic targeting while surgical technology becomes adapted to patient-specific symptomatology and structural/functional imaging parameters. This individualized approach has already begun to show significant promise when applied to deep brain stimulation for treatment-resistant depression and obsessive-compulsive disorder. If effectiveness of these strategies is confirmed by well designed, double-blind, placebo-controlled clinical studies, further technological advances will continue into the distant future, and will likely involve precise neuromodulation at the cellular level, perhaps using wireless technology with or without closed-loop design. This approach, being theoretically less invasive and carrying less risk, may ultimately propel psychiatric neurosurgery to the forefront in the treatment algorithm of mental illness. Despite prominent development of non-invasive therapeutic options, such as stereotactic radiosurgery or transcranial magnetic resonance-guided focused ultrasound, chances are there will still be a need in surgical management of patients with most intractable psychiatric conditions.

Anatomical variability, multi-modal coordinate systems, and precision targeting in the marmoset brain

Localising accurate brain regions needs careful evaluation in each experimental species due to their individual variability. However, the function and connectivity of brain areas is commonly studied using a single-subject cranial landmark-based stereotactic atlas in animal neuroscience. Here, we address this issue in a small primate, the common marmoset, which is increasingly widely used in systems neuroscience. We developed a non-invasive multi-modal neuroimaging-based targeting pipeline, which accounts for intersubject anatomical variability in cranial and cortical landmarks in marmosets. This methodology allowed creation of multi-modal templates (MarmosetRIKEN20) including head CT and brain MR images, embedded in coordinate systems of anterior and posterior commissures (AC-PC) and CIFTI grayordinates. We found that the horizontal plane of the stereotactic coordinate was significantly rotated in pitch relative to the AC-PC coordinate system (10 degrees, frontal downwards), and had a significant bias and uncertainty due to positioning procedures. We also found that many common cranial and brain landmarks (e.g., bregma, intraparietal sulcus) vary in location across subjects and are substantial relative to average marmoset cortical area dimensions. Combining the neuroimaging-based targeting pipeline with robot-guided surgery enabled proof-of-concept targeting of deep brain structures with an accuracy of 0.2 mm. Altogether, our findings demonstrate substantial intersubject variability in marmoset brain and cranial landmarks, implying that subject-specific neuroimaging-based localization is needed for precision targeting in marmosets. The population-based templates and atlases in grayordinates, created for the first time in marmoset monkeys, should help bridging between macroscale and microscale analyses.

Pre-Clinical Development of Robot-Assisted Ventriculoscopy for 3D Image Reconstruction and Guidance of Deep Brain Neurosurgery

Conventional neuro-navigation can be challenged in targeting deep brain structures via transventricular neuroendoscopy due to unresolved geometric error following soft-tissue deformation. Current robot-assisted endoscopy techniques are fairly limited, primarily serving to planned trajectories and provide a stable scope holder. We report the implementation of a robot-assisted ventriculoscopy (RAV) system for 3D reconstruction, registration, and augmentation of the neuroendoscopic scene with intraoperative imaging, enabling guidance even in the presence of tissue deformation and providing visualization of structures beyond the endoscopic field-of-view. Phantom studies were performed to quantitatively evaluate image sampling requirements, registration accuracy, and computational runtime for two reconstruction methods and a variety of clinically relevant ventriculoscope trajectories. A median target registration error of 1.2 mm was achieved with an update rate of 2.34 frames per second, validating the RAV concept and motivating translation to future clinical studies.

Measurement of Lead Localization Accuracy Based on Magnetic Resonance Imaging

Post-implantation localization of deep brain stimulation (DBS) lead based on a magnetic resonance (MR) image is widely used. Existing localization methods use artifact center method or template registration method, which may lead to a considerable deviation of > 2 mm, and result in severe side effects or even surgical failure. Accurate measurement of lead position can instantly inform surgeons of the imprecise implantation. This study aimed to identify the influencing factors in DBS lead post-implantation localization approach, analyze their influence, and describe a localization approach that uses the individual template method to reduce the deviation. We verified that reconstructing direction should be parallel or perpendicular to lead direction, instead of the magnetic field. Besides, we used simplified relationship between magnetic field angle and deviation error to correct the localization results. The mean localization error can be reduced after correction and favors the feasibility of direct localization of DBS lead using MR images. We also discussed influence of in vivo noise on localization frequency and the possibility of using only MR images to localize the contacts.

Restoring Sensorimotor Function Through Neuromodulation After Spinal Cord Injury: Progress and Remaining Challenges

Spinal cord injury (SCI) is a major disability that results in motor and sensory impairment and extensive complications for the affected individuals which not only affect the quality of life of the patients but also result in a heavy burden for their families and the health care system. Although there are few clinically effective treatments for SCI, research over the past few decades has resulted in several novel treatment strategies which are related to neuromodulation. Neuromodulation-the use of neuromodulators, electrical stimulation or optogenetics to modulate neuronal activity-can substantially promote the recovery of sensorimotor function after SCI. Recent studies have shown that neuromodulation, in combination with other technologies, can allow paralyzed patients to carry out intentional, controlled movement, and promote sensory recovery. Although such treatments hold promise for completely overcoming SCI, the mechanisms by which neuromodulation has this effect have been difficult to determine. Here we review recent progress relative to electrical neuromodulation and optogenetics neuromodulation. We also examine potential mechanisms by which these methods may restore sensorimotor function. We then highlight the strengths of these approaches and remaining challenges with respect to its application.

Full-field MRI measurements of in-vivo positional brain shift reveal the significance of intra-cranial geometry and head orientation for stereotactic surgery

Positional brain shift (PBS), the sagging of the brain under the effect of gravity, is comparable in magnitude to the margin of error for the success of stereotactic interventions ([Formula: see text] 1 mm). This non-uniform shift due to slight differences in head orientation can lead to a significant discrepancy between the planned and the actual location of surgical targets. Accurate in-vivo measurements of this complex deformation are critical for the design and validation of an appropriate compensation to integrate into neuronavigational systems. PBS arising from prone-to-supine change of head orientation was measured with magnetic resonance imaging on 11 young adults. The full-field displacement was extracted on a voxel-basis via digital volume correlation and analysed in a standard reference space. Results showed the need for target-specific correction of surgical targets, as a significant displacement ranging from 0.52 to 0.77 mm was measured at surgically relevant structures. Strain analysis further revealed local variability in compressibility: anterior regions showed expansion (both volume and shape change), whereas posterior regions showed small compression, mostly dominated by shape change. Finally, analysis of correlation demonstrated the potential for further patient- and intervention-specific adjustments, as intra-cranial breadth and head tilt correlated with PBS reaching statistical significance.

Evolution of Globus Pallidus Targeting for Parkinson's and Dystonia Deep Brain Stimulation: A 15-Year Experience

Objective: The aim of this study is to evaluate the evolution of GPi DBS targeting.

Methods: This retrospective, single-center study included patients implanted with GPi DBS leads for dystonia or PD during the years 2004 to 2018 at the University of Florida Fixel Institute for Neurological Diseases. Each patient underwent a high-resolution targeting study on the day prior to the surgery, which was fused with a high resolution CT scan that was acquired on the day of the procedure. Intraoperative target location was selected using a digitized 3D Schaltenbrand-Bailey atlas. All patients underwent a high-resolution head CT scan without contrast approximately one month after lead implantation and accurate measurement of neuroanatomical lead position was acquired after fusion of pre-operative and post-operative image studies.

Results: We analyzed 253 PD patients with 352 leads and 80 dystonia patients with 141 leads. During 15 years of follow-up, lead locations in the PD group migrated more laterally (β = 0.09, p < 0.0001), posteriorly [slope (β) = 0.04, p < 0.05], and dorsally (β = 0.07, p < 0.001), whereas leads in the dystonia group did not significantly change position aside from a trend in the dorsal direction (β = 0.06, p = 0.053).

Conclusion: The evolving target likely results from multiple factors including improvements in targeting techniques and clinical feedback intraoperatively and post-operatively. Our demonstrates the potential importance of a systematic post-operative DBS lead measurement protocol to ensure quality control and to inform and optimize DBS programming.

The Clinical Application of Robot-Assisted Ventriculoperitoneal Shunting in the Treatment of Hydrocephalus

Background

This work aims to assess the effectiveness and safety of robotic assistance in ventriculoperitoneal shunting and to compare the results with data from traditional surgery.

Methods

We retrospectively analyzed 60 patients who had undergone ventriculoperitoneal shunting, of which shunts were implanted using a robot in 20 patients and using traditional surgical methods in the other 40 patients. Data related to surgery were compared between the two groups, and the accuracy of the drainage tube in the robot-assisted group was assessed.

Results

In the robot-assisted surgery group, the operation duration was 29.75 ± 6.38 min, intraoperative blood loss was 10.0 ± 3.98 ml, the success rate of a single puncture was 100%, and the bone hole diameter was 4.0 ± 0.3 mm. On the other hand, the operation duration was 48.63 ± 6.60 min, intraoperative blood loss was 22.25 ± 4.52 ml, the success rate of a single puncture was 77.5%, and the bone hole diameter was 11.0 ± 0.2 mm in the traditional surgery group. The above are statistically different between the two groups (P < 0.05). Only one case of surgery-related complications occurred in the robot-assisted group, while 13 cases occurred in the traditional surgery group. There was no significant difference in the hospitalization time. In the robot-assisted surgery group, the average radial error was 2.4 ± 1.5 mm and the average axial error was 1.9 ± 2.1 mm.

Conclusion

In summary, robot-assisted implantation is accurate, simple to operate, and practical; the duration of surgery is short; trauma to the patient is reduced; and fewer postoperative complications related to surgery are reported.

Asleep deep brain stimulation with intraoperative magnetic resonance guidance: a single-institution experience

OBJECTIVE

Deep brain stimulation (DBS) is traditionally performed on an awake patient with intraoperative recordings and test stimulation. DBS performed under general anesthesia with intraoperative MRI (iMRI) has demonstrated high target accuracy, reduced operative time, direct confirmation of target placement, and the ability to place electrodes without cessation of medications. The authors describe their initial experience with using iMRI to perform asleep DBS and discuss the procedural and radiological outcomes of this procedure.

METHODS

All DBS electrodes were implanted under general anesthesia by a single surgeon by using a neuronavigation system with 3-T iMRI guidance. Clinical outcomes, operative duration, complications, and accuracy were retrospectively analyzed.

RESULTS

In total, 103 patients treated from 2015 to 2019 were included, and all but 1 patient underwent bilateral implantation. Indications included Parkinson's disease (PD) (65% of patients), essential tremor (ET) (29%), dystonia (5%), and refractory epilepsy (1%). Targets included the globus pallidus pars internus (12.62% of patients), subthalamic nucleus (56.31%), ventral intermedius nucleus of the thalamus (30%), and anterior nucleus of the thalamus (1%). Technically accurate lead placement (radial error ≤ 1 mm) was obtained for 98% of leads, with a mean (95% CI) radial error of 0.50 (0.46-0.54) mm; all leads were placed with a single pass. Predicted radial error was an excellent predictor of real radial error, underestimating real error by only a mean (95% CI) of 0.16 (0.12-0.20) mm. Accuracy remained high irrespective of surgeon experience, but procedure time decreased significantly with increasing institutional and surgeon experience (p = 0.007), with a mean procedure duration of 3.65 hours. Complications included 1 case of intracranial hemorrhage (asymptomatic) and 1 case of venous infarction (symptomatic), and 2 patients had infection at the internal pulse generator site. The mean ± SD voltage was 2.92 ± 0.83 V bilaterally at 1-year follow-up. Analysis of long-term clinical efficacy demonstrated consistent postoperative improvement in clinical symptoms, as well as decreased drug doses across all indications and follow-up time points, including mean decrease in levodopa-equivalent daily dose by 53.57% (p < 0.0001) in PD patients and mean decrease in primidone dose by 61.33% (p < 0.032) in ET patients at 1-year follow-up.

CONCLUSIONS

A total of 205 leads were placed in 103 patients by a single surgeon under iMRI guidance with few operative complications. Operative time trended downward with increasing institutional experience, and technical accuracy of radiographic lead placement was consistently high. Asleep DBS implantation with iMRI appears to be a safe and effective alternative to standard awake procedures.

Robotic Applications in Cranial Neurosurgery: Current and Future

Robotics applied to cranial surgery is a fast-moving and fascinating field, which is transforming the practice of neurosurgery. With exponential increases in computing power, improvements in connectivity, artificial intelligence, and enhanced precision of accessing target structures, robots are likely to be incorporated into more areas of neurosurgery in the future-making procedures safer and more efficient. Overall, improved efficiency can offset upfront costs and potentially prove cost-effective. In this narrative review, we aim to translate a broad clinical experience into practical information for the incorporation of robotics into neurosurgical practice. We begin with procedures where robotics take the role of a stereotactic frame and guide instruments along a linear trajectory. Next, we discuss robotics in endoscopic surgery, where the robot functions similar to a surgical assistant by holding the endoscope and providing retraction, supplemental lighting, and correlation of the surgical field with navigation. Then, we look at early experience with endovascular robots, where robots carry out tasks of the primary surgeon while the surgeon directs these movements remotely. We briefly discuss a novel microsurgical robot that can perform many of the critical operative steps (with potential for fine motor augmentation) remotely. Finally, we highlight 2 innovative technologies that allow instruments to take nonlinear, predetermined paths to an intracranial destination and allow magnetic control of instruments for real-time adjustment of trajectories. We believe that robots will play an increasingly important role in the future of neurosurgery and aim to cover some of the aspects that this field holds for neurosurgical innovation.

Functional Neuroimaging During Asleep DBS Surgery: A Proof of Concept Study

Object: A real-time functional magnetic resonance imaging (fMRI) feedback during ventral intermediate nucleus (VIM) deep brain stimulation (DBS) under general anesthesia (or “asleep” DBS) does not exist. We hypothesized that it was feasible to acquire a reliable and responsive fMRI during asleep VIM DBS surgery.

Methods: We prospectively enrolled 10 consecutive patients who underwent asleep DBS for the treatment of medication-refractory essential tremor. Under general anesthesia, we acquired resting-state functional MRI immediately before and after the cannula insertion. Reliability was determined by a temporal signal-to-noise-ratio >100. Responsiveness was determined based on the fMRI signal change upon insertion of the cannula to the VIM.

Results: It was feasible to acquire reliable fMRI during asleep DBS surgery. The fMRI signal was responsive to the brain cannula insertion, revealing a reduction in the tremor network's functional connectivity, which did not reach statistical significance in the group analysis.

Conclusions: It is feasible to acquire a reliable and responsive fMRI signal during asleep DBS. The acquisition steps and the preprocessing pipeline developed in these experiments will be useful for future investigations to develop fMRI-based feedback for asleep DBS surgery.

Two Hundred Twenty-Six Consecutive Deep Brain Stimulation Electrodes Placed Using an "Asleep" Technique and the Neuro|MateTM Robot for the Treatment of Movement Disorders

BACKGROUND

Robotics in neurosurgery has demonstrated widening indications and rapid growth in recent years. Robotic precision and reproducibility are especially pertinent to the field of functional neurosurgery. Deep brain stimulation (DBS) requires accurate placement of electrodes in order to maximize efficacy and minimize side effects. In addition, asleep techniques demand clear target visualization and immediate on-table verification of accuracy.

OBJECTIVE

To describe the surgical technique of asleep DBS surgery using the Neuro|MateTM Robot (Renishaw plc, Wotton-under-Edge, United Kingdom) and examine the accuracy of DBS lead placement in the subthalamic nucleus (STN) for the treatment of movement disorders.

METHODS

A single-center retrospective review of 113 patients who underwent bilateral STN/Zona Incerta electrode placement was performed. Accuracy of implantation was assessed using 5 measurements, Euclidian distance, radial error, depth error, angular error, and shift error.

RESULTS

A total of 226 planned vs actual electrode placements were analyzed. The mean 3-dimensional vector error calculated for 226 trajectories was 0.78 +/- 0.37 mm. The mean radial displacement off planned trajectory was 0.6 +/- 0.33 mm. The mean depth error, angular error, and shift error was 0.4 +/- 0.35 mm, 0.4 degrees, and 0.3 mm, respectively.

CONCLUSION

This report details our institution's method for DBS lead placement in patients under general anaesthesia using anatomical targeting without microelectrode recordings or intraoperative test stimulation for the treatment of movement disorders. This is the largest reported dataset of accuracy results in DBS surgery performed asleep. This novel robot-assisted operative technique results in sub-millimeter accuracy in DBS electrode placement.

Robot-Assisted Stereotaxy Reduces Target Error: A Meta-Analysis and Meta-Regression of 6056 Trajectories

BACKGROUND

The pursuit of improved accuracy for localization and electrode implantation in deep brain stimulation (DBS) and stereoelectroencephalography (sEEG) has fostered an abundance of disparate surgical/stereotactic practices. Specific practices/technologies directly modify implantation accuracy; however, no study has described their respective influence in multivariable context.

OBJECTIVE

To synthesize the known literature to statistically quantify factors affecting implantation accuracy.

METHODS

A systematic review and meta-analysis was conducted to determine the inverse-variance weighted pooled mean target error (MTE) of implanted electrodes among patients undergoing DBS or sEEG. MTE was defined as Euclidean distance between planned and final electrode tip. Meta-regression identified moderators of MTE in a multivariable-adjusted model.

RESULTS

A total of 37 eligible studies were identified from a search return of 2,901 potential articles (2002-2018) - 27 DBS and 10 sEEG. Random-effects pooled MTE = 1.91 mm (95% CI: 1.7-2.1) for DBS and 2.34 mm (95% CI: 2.1-2.6) for sEEG. Meta-regression identified study year, robot use, frame/frameless technique, and intraoperative electrophysiologic testing (iEPT) as significant multivariable-adjusted moderators of MTE (P < .0001, R2 = 0.63). Study year was associated with a 0.92-mm MTE reduction over the 16-yr study period (P = .0035), and robot use with a 0.79-mm decrease (P = .0019). Frameless technique was associated with a mean 0.50-mm (95% CI: 0.17-0.84) increase, and iEPT use with a 0.45-mm (95% CI: 0.10-0.80) increase in MTE. Registration method, imaging type, intraoperative imaging, target, and demographics were not significantly associated with MTE on multivariable analysis.

CONCLUSION

Robot assistance for stereotactic electrode implantation is independently associated with improved accuracy and reduced target error. This remains true regardless of other procedural factors, including frame-based vs frameless technique.

Frameless stereotactic brain biopsy: A prospective study on robot-assisted brain biopsies performed on 32 patients by using the RONNA G4 system

BACKGROUND

We present a novel robotic neuronavigation system (RONNA G4), used for precise preoperative planning and frameless neuronavigation, developed by a research group from the University of Zagreb and neurosurgeons from the University Hospital Dubrava, Zagreb, Croatia. The aim of study is to provide comprehensive error measurement analysis of the system used for the brain biopsy.

METHODS

Frameless stereotactic robot-assisted biopsies were performed on 32 consecutive patients. Post-operative CT and MRI scans were assessed to precisely measure and calculate target point error (TPE) and entry point error (EPE).

RESULTS

The application accuracy of the RONNA system for TPE was 1.95 ± 1.11 mm, while for EPE was 1.42 ± 0.74 mm. The total diagnostic yield was 96.87%. Linear regression showed statistical significance between the TPE and EPE, and the angle of the trajectory on the bone.

CONCLUSION

The RONNA G4 robotic system is a precise and highly accurate autonomous neurosurgical assistant for performing frameless brain biopsies.

Clinical outcomes of globus pallidus deep brain stimulation for Parkinson disease: a comparison of intraoperative MRI- and MER-guided lead placement

OBJECTIVE

Deep brain stimulation (DBS) lead placement is increasingly performed with the patient under general anesthesia by surgeons using intraoperative MRI (iMRI) guidance without microelectrode recording (MER) or macrostimulation. The authors assessed the accuracy of lead placement, safety, and motor outcomes in patients with Parkinson disease (PD) undergoing DBS lead placement into the globus pallidus internus (GPi) using iMRI or MER guidance.

METHODS

The authors identified all patients with PD who underwent either MER- or iMRI-guided GPi-DBS lead placement at Emory University between July 2007 and August 2016. Lead placement accuracy and adverse events were determined for all patients. Clinical outcomes were assessed using the Unified Parkinson's Disease Rating Scale (UPDRS) part III motor scores for patients completing 12 months of follow-up. The authors also assessed the levodopa-equivalent daily dose (LEDD) and stimulation parameters.

RESULTS

Seventy-seven patients were identified (MER, n = 28; iMRI, n = 49), in whom 131 leads were placed. The stereotactic accuracy of the surgical procedure with respect to the planned lead location was 1.94 ± 0.21 mm (mean ± SEM) (95% CI 1.54-2.34) with frame-based MER and 0.84 ± 0.007 mm (95% CI 0.69-0.98) with iMRI. The rate of serious complications was similar, at 6.9% for MER-guided DBS lead placement and 9.4% for iMRI-guided DBS lead placement (RR 0.71 [95% CI 0.13%-3.9%]; p = 0.695). Fifty-seven patients were included in clinical outcome analyses (MER, n = 16; iMRI, n = 41). Both groups had similar characteristics at baseline, although patients undergoing MER-guided DBS had a lower response on their baseline levodopa challenge (44.8% ± 5.4% [95% CI 33.2%-56.4%] vs 61.6% ± 2.1% [95% CI 57.4%-65.8%]; t = 3.558, p = 0.001). Greater improvement was seen following iMRI-guided lead placement (43.2% ± 3.5% [95% CI 36.2%-50.3%]) versus MER-guided lead placement (25.5% ± 6.7% [95% CI 11.1%-39.8%]; F = 5.835, p = 0.019). When UPDRS III motor scores were assessed only in the contralateral hemibody (per-lead analyses), the improvements remained significantly different (37.1% ± 7.2% [95% CI 22.2%-51.9%] and 50.0% ± 3.5% [95% CI 43.1%-56.9%] for MER- and iMRI-guided DBS lead placement, respectively). Both groups exhibited similar reductions in LEDDs (21.2% and 20.9%, respectively; F = 0.221, p = 0.640). The locations of all active contacts and the 2D radial distance from these to consensus coordinates for GPi-DBS lead placement (x, ±20; y, +2; and z, -4) did not differ statistically by type of surgery.

CONCLUSIONS

iMRI-guided GPi-DBS lead placement in PD patients was associated with significant improvement in clinical outcomes, comparable to those observed following MER-guided DBS lead placement. Furthermore, iMRI-guided DBS implantation produced a similar safety profile to that of the MER-guided procedure. As such, iMRI guidance is an alternative to MER guidance for patients undergoing GPi-DBS implantation for PD.

The Accuracy of Direct Targeting Using Fusion of MR and CT Imaging for Deep Brain Stimulation of the Subthalamic Nucleus in Patients with Parkinson's Disease

INTRODUCTION

 In 33 consecutive patients with Parkinson's disease (PD) undergoing awake deep brain stimulation (DBS) without microelectrode recording (MER), we assessed and validated the precision and accuracy of direct targeting of the subthalamic nucleus (STN) using preoperative magnetic resonance imaging (MRI) and stereotactic computed tomography (CT) image fusion combined with immediate postoperative stereotactic CT and postoperative MRI, and we report on the side effects and clinical results up to 6 months' follow-up.

MATERIALS AND METHODS

 Preoperative nonstereotactic MRI and stereotactic CT images were merged and used for planning the trajectory and final lead position. Immediate postoperative stereotactic CT and postoperative nonstereotactic MRI provided the validation of the final electrode position. Changes in the Unified Parkinson's Disease Rating Scale III (UPDRS III) scores and the levodopa equivalent daily doses (LEDD) and appearance of adverse side effects were assessed.

RESULTS

 The mean Euclidian distance (ED) error between the planned position and the final position of the lead in the left STN was 1.69 ± 0.82 mm and that in the right STN was 2.12 ± 1.00. The individual differences between planned and final position in each of the three coordinates were less than 2 mm. The UPDRS III scores improved by 75% and LEDD decreased by 45%. Few patients experienced complications, such as postoperative infection (n = 1), or unwanted side effects, such as emotional instability (n = 1).

CONCLUSION

 Our results confirm that direct targeting of an STN on stereotactic CT merged with MRI could be a valid method for placement the DBS electrode. The magnitude of our targeting error is comparable with the reported errors when using MER and other direct targeting approaches.

Targeting of the Subthalamic Nucleus in Patients with Parkinson's Disease Undergoing Deep Brain Stimulation Surgery

Precise stereotactic targeting of the dorsolateral motor part of the subthalamic nucleus (STN) is paramount for maximizing clinical effectiveness and preventing side effects of deep brain stimulation (DBS) in patients with advanced Parkinson's disease. With recent developments in magnetic resonance imaging (MRI) techniques, direct targeting of the dorsolateral part of the STN is now feasible, together with visualization of the motor fibers in the nearby internal capsule. However, clinically relevant discrepancies were reported when comparing STN borders on MRI to electrophysiological STN borders during microelectrode recordings (MER). Also, one should take into account the possibility of a 3D inaccuracy of up to 2 mm of the applied stereotactic technique. Pneumocephalus and image fusion errors may further increase implantation inaccuracy. Even when implantation has been successful, suboptimal lead anchoring on the skull may cause lead migration during follow-up. Meticulous pre- and intraoperative imaging is therefore indispensable, and so is postoperative imaging when the effects of DBS deteriorate during follow-up. Thus far, most DBS centers employ MRI targeting, multichannel MER, and awake test stimulation in STN surgery, but randomized trials comparing surgery under local versus general anesthesia and additional studies comparing MER-STN borders to high-field MRI-STN may change this clinical practice. Further developments in imaging protocols and improvements in image fusion processes are needed to optimize placement of DBS leads in the dorsolateral motor part of the STN in Parkinson's disease.

O-Arm Stereotactic Imaging in Deep Brain Stimulation Surgery Workflow: A Utility and Cost-Effectiveness Analysis

INTRODUCTION

Deep brain stimulation (DBS) surgery is an established treatment for movement disorders. Advances in neuroimaging techniques have resulted in improved targeting accuracy that may improve clinical outcomes. This study aimed to evaluate the safety and feasibility of using the Medtronic O-arm device for the acquisition of intraoperative stereotactic imaging, targeting, and localization of DBS electrodes compared with standard stereotactic MRI or computed tomography (CT).

METHODS

Patients were recruited prospectively into the study. Routine frame-based stereotactic DBS surgery was performed. Intraoperative imaging was used to facilitate and verify the accurate placement of the intracranial electrodes. The acquisition of coordinates and verification of the position of the electrodes using the O-arm were evaluated and compared with conventional stereotactic MRI or CT. Additionally, a systematic review of the literature on the use of intraoperative imaging in DBS surgery was performed.

RESULTS

Eighty patients were included. The indications for DBS surgery were dystonia, Parkinson's disease, essential tremor, and epilepsy. The globus pallidus internus was the most commonly targeted region (43.7%), followed by the subthalamic nucleus (35%). Stereotactic O-arm imaging reduced the overall surgical time by 68 min, reduced the length of time of acquisition of stereotactic images by 77%, reduced patient exposure to ionizing radiation by 24.2%, significantly reduced operating room (OR) costs per procedure by 31%, and increased the OR and neuroradiology suite availability.

CONCLUSIONS

The use of the O-arm in DBS surgery workflow significantly reduced the duration of image acquisition, the exposure to ionizing radiation, and costs when compared with standard stereotactic MRI or CT, without reducing accuracy.

Clinical outcomes of pallidal deep brain stimulation for dystonia implanted using intraoperative MRI

OBJECTIVE

Lead placement for deep brain stimulation (DBS) using intraoperative MRI (iMRI) relies solely on real-time intraoperative neuroimaging to guide electrode placement, without microelectrode recording (MER) or electrical stimulation. There is limited information, however, on outcomes after iMRI-guided DBS for dystonia. The authors evaluated clinical outcomes and targeting accuracy in patients with dystonia who underwent lead placement using an iMRI targeting platform.

METHODS

Patients with dystonia undergoing iMRI-guided lead placement in the globus pallidus pars internus (GPi) were identified. Patients with a prior ablative or MER-guided procedure were excluded from clinical outcomes analysis. Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) scores and Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) scores were assessed preoperatively and at 6 and 12 months postoperatively. Other measures analyzed include lead accuracy, complications/adverse events, and stimulation parameters.

RESULTS

A total of 60 leads were implanted in 30 patients. Stereotactic lead accuracy in the axial plane was 0.93 ± 0.12 mm from the intended target. Nineteen patients (idiopathic focal, n = 7; idiopathic segmental, n = 5; DYT1, n = 1; tardive, n = 2; other secondary, n = 4) were included in clinical outcomes analysis. The mean improvement in BFMDRS score was 51.9% ± 9.7% at 6 months and 63.4% ± 8.0% at 1 year. TWSTRS scores in patients with predominant cervical dystonia (n = 13) improved by 53.3% ± 10.5% at 6 months and 67.6% ± 9.0% at 1 year. Serious complications occurred in 6 patients (20%), involving 8 of 60 implanted leads (13.3%). The rate of serious complications across all patients undergoing iMRI-guided DBS at the authors' institution was further reviewed, including an additional 53 patients undergoing GPi-DBS for Parkinson disease. In this expanded cohort, serious complications occurred in 11 patients (13.3%) involving 15 leads (10.1%).

CONCLUSIONS

Intraoperative MRI-guided lead placement in patients with dystonia showed improvement in clinical outcomes comparable to previously reported results using awake MER-guided lead placement. The accuracy of lead placement was high, and the procedure was well tolerated in the majority of patients. However, a number of patients experienced serious adverse events that were attributable to the introduction of a novel technique into a busy neurosurgical practice, and which led to the revision of protocols, product inserts, and on-site training.

Intraoperative Neurophysiologic Assessment in Deep Brain Stimulation Surgery and its Impact on Lead Placement

OBJECTIVES

 While the efficacy of deep brain stimulation (DBS) to treat various neurological disorders is undisputed, the surgical methods differ widely and the importance of intraoperative microelectrode recording (MER) or macrostimulation (MS) remains controversially debated. The objective of this study is to evaluate the impact of MER and MS on intraoperative lead placement.

PATIENTS AND METHODS

 We included 101 patients who underwent awake bilateral implantation of electrodes in the subthalamic nucleus with MER and MS for Parkinson's disease from 2009 to 2017 in a retrospective observational study. We analyzed intraoperative motor outcomes between anatomically planned stimulation point (PSP) and definite stimulation point (DSP), lead adjustments and Unified Parkinson's Disease Rating Scale Item III (UPDRS-III), levodopa equivalent daily dose (LEDD), and adverse events (AE) after 6 months.

RESULTS

 We adjusted 65/202 leads in 47/101 patients. In adjusted leads, MS results improved significantly when comparing PSP and DSP (p < 0.001), resulting in a number needed to treat of 9.6. After DBS, UPDRS-III and LEDD improved significantly after 6 months in adjusted and nonadjusted patients (p < 0.001). In 87% of leads, the active contact at 6 months still covered the optimal stimulation point during surgery. In total, 15 AE occurred.

CONCLUSION

 MER and MS have a relevant impact on the intraoperative decision of final lead placement and prevent from a substantial rate of poor stimulation outcome. The optimal stimulation points during surgery and chronic stimulation strongly overlap. Follow-up UPDRS-III results, LEDD reductions, and DBS-related AE correspond well to previously published data.

Bilateral Subthalamic Nucleus Deep Brain Stimulation under General Anesthesia: Literature Review and Single Center Experience

Bilateral subthalamic nucleus (STN) Deep brain stimulation (DBS) is a well-established treatment in patients with Parkinson's disease (PD). Traditionally, STN DBS for PD is performed by using microelectrode recording (MER) and/or intraoperative macrostimulation under local anesthesia (LA). However, many patients cannot tolerate the long operation time under LA without medication. In addition, it cannot be even be performed on PD patients with poor physical and neurological condition. Recently, it has been reported that STN DBS under general anesthesia (GA) can be successfully performed due to the feasible MER under GA, as well as the technical advancement in direct targeting and intraoperative imaging. The authors reviewed the previously published literature on STN DBS under GA using intraoperative imaging and MER, focused on discussing the technique, clinical outcome, and the complication, as well as introducing our single-center experience. Based on the reports of previously published studies and ours, GA did not interfere with the MER signal from STN. STN DBS under GA without intraoperative stimulation shows similar or better clinical outcome without any additional complication compared to STN DBS under LA. Long-term follow-up with a large number of the patients would be necessary to validate the safety and efficacy of STN DBS under GA.

Sensor Modalities for Brain-Computer Interface Technology: A Comprehensive Literature Review

Brain-computer interface (BCI) technology is rapidly developing and changing the paradigm of neurorestoration by linking cortical activity with control of an external effector to provide patients with tangible improvements in their ability to interact with the environment. The sensor component of a BCI circuit dictates the resolution of brain pattern recognition and therefore plays an integral role in the technology. Several sensor modalities are currently in use for BCI applications and are broadly either electrode-based or functional neuroimaging-based. Sensors vary in their inherent spatial and temporal resolutions, as well as in practical aspects such as invasiveness, portability, and maintenance. Hybrid BCI systems with multimodal sensory inputs represent a promising development in the field allowing for complimentary function. Artificial intelligence and deep learning algorithms have been applied to BCI systems to achieve faster and more accurate classifications of sensory input and improve user performance in various tasks. Neurofeedback is an important advancement in the field that has been implemented in several types of BCI systems by showing users a real-time display of their recorded brain activity during a task to facilitate their control over their own cortical activity. In this way, neurofeedback has improved BCI classification and enhanced user control over BCI output. Taken together, BCI systems have progressed significantly in recent years in terms of accuracy, speed, and communication. Understanding the sensory components of a BCI is essential for neurosurgeons and clinicians as they help advance this technology in the clinical setting.

Non-staged bilateral Globus Pallidus Internus deep brain stimulation lead revision using intraoperative MRI: a case report and literature review

BACKGROUND

Deep brain stimulation (DBS) lead revision due to suboptimal therapy is common but there is no standardised protocol. We describe a novel technique using iMRI to perform concurrent new Globus Pallidus Internus (GPi) DBS lead implantation and old lead removal in a dystonia patient.Case-description: A 60-year-old woman with medication and neurotoxin-refractory isolated cervical dystonia underwent awake bilateral GPi DBS surgery with MER-guided lead implantation. She initially had a favourable response but later reported suboptimal benefit despite reprogramming. MRI demonstrated suboptimal lead placement and MRI-guided revision surgery under general anesthesia was planned. The goal was to place new leads superior and medial to the existing leads. Using a 1.5 T iMRI and the ClearPoint^® NeuroNavigation system, new leads were placed through the existing burr holes, into the new targets with radial errors < 0.08mm bilaterally without crossing the old leads. The old leads were then removed and the new leads connected to the existing pulse generator. The patient tolerated the procedure well and had improved side-effect profile at all contacts at 1-month follow-up.

CONCLUSIONS

Non-staged iMRI-guided DBS revision surgery under general anesthesia is technically feasible and is an alternative strategy to a staged iMRI-guided revision surgery or an awake MER-guided revision surgery in select patients.

Frameless stereotaxy in subthalamic deep brain stimulation: 3-year clinical outcome

Background

In most centers, the surgery of deep brain stimulation (DBS) is performed using a stereotactic frame. Compared with frame-based technique, frameless stereotaxy reduces the duration of surgical procedure and patient’s discomfort, with lead placing accuracy equivalent after the learning curve. Although several studies have investigated the targeting accuracy of this technique, only a few studies reported clinical outcomes, with data of short-term follow-up.

Objective

To assess clinical efficacy and safety of frameless bilateral subthalamic nucleus (STN) DBS in Parkinson’s disease (PD) patients at 1- and 3-year follow-up.

Methods

Consecutive PD patients who underwent bilateral STN-DBS with a manual adjustable frameless system were included in the study. The data were collected retrospectively.

Results

Eighteen PD patients underwent bilateral STN-DBS implant and were included in the study. All patients completed 1-year observation and ten of them completed 3-year observation. At 1-year follow-up, motor efficacy of STN stimulation in off-med condition was of 30.1% (P = 0.003) and at 3-year follow-up was of 36.3%, compared with off-stim condition at 3-year follow-up (P = 0.005). Dopaminergic drugs were significantly reduced by 31.2% 1 year after the intervention (P = 0.003) and 31.7% 3 years after the intervention (P = 0.04). No serious adverse events occurred during surgery.

Conclusions

Frameless stereotaxy is an effective and safe technique for DBS surgery at 1- and 3-year follow-up, with great advantages for patients’ discomfort during surgery.

Asleep Deep Brain Stimulation of the Nucleus Ventralis Intermedius for Essential Tremor Using Indirect Targeting and Interventional Magnetic Resonance Imaging: Single-Institution Case Series

BACKGROUND

Literature on asleep deep brain stimulation (DBS) of the ventralis intermedius (Vim) nucleus in essential tremor is relatively sparse. Furthermore, controversy exists as to whether indirect ("consensus" or "atlas-based") targeting of the Vim requires physiologic adjustment for effective clinical outcomes in DBS surgery.

OBJECTIVES

The objective of this study was to evaluate the clinical results of asleep Vim DBS using indirect coordinates and real-time interventional magnetic resonance imaging guidance.

METHODS

Retrospective review of a prospectively collected database was performed to identify patients with essential tremor undergoing asleep Vim DBS using interventional magnetic resonance imaging guidance. Stereotactic and clinical outcomes were abstracted and analyzed using descriptive statistics.

RESULTS

A total of 12 consecutive patients were identified, all of whom were available for 6-month clinical follow-up. Stereotactic (radial) error was 0.5 ± 0.2 mm on the left and 0.5 ± 0.3 mm on the right. Fahn-Tolosa-Marin tremor scores in the treated limb(s) decreased by 71.2% ± 31.0% (P = 0.0088), The Essential Tremor Rating Assessment Scale activities of daily living improved by 74.9% ± 23.7% (P < 0.0001), and The Essential Tremor Rating Assessment Scale performance improved by 64.3 ± 16.2% (P = 0.0004). Surgical complications were mild and generally transient. Stimulation-related side effects were similar to those reported in historical series of awake Vim DBS.

CONCLUSIONS

Asleep Vim DBS using indirect targeting and interventional magnetic resonance imaging-guided placement is safe and effective, with 6-month clinical results similar to those achieved with awake placement. These data support the use of asleep surgery in essential tremor and represent a baseline for comparison with future studies using more advanced targeting techniques.

An initial experience with intraoperative O-Arm for deep brain stimulation surgery: can it replace post-operative MRI?

Deep brain stimulation (DBS) is used to treat movement disorders, severe psychiatric disorders, and neuropathic pain, among other diseases. Advanced neuroimaging techniques allow direct or indirect localization of the target site, which is verified in many centers by the intraoperative recording of unitary neuronal activity. Intraoperative image acquisition technology (e.g., O-Arm) is increasingly used for accurate electrode positioning throughout the surgery. The aim of our study is to analyze the initial experience of our team in the utilization of O-Arm for planning DBS and monitoring its precision and accuracy throughout the procedure. The study included 13 patients with movement disorders. All underwent DBS with the intraoperative O-arm image acquisition system (iCT) and Medtronic StealthStation S7 cranial planning system, placing a total of 25 electrodes. For each patient, we calculated the difference between real and theoretic x, y, z coordinates, using the paired Student's t test to evaluate absolute and directional differences and the one-sample Student's t test to analyze differences in Euclidean distances. No statistically significant differences were found in absolute, directional, or Euclidean distances between intended and actual x, y, and z coordinates, based on iCT scan. Our experience confirms that utilization of the O-Arm system in DBS provides accurate and precise verification of electrode placements throughout the procedure. Recent studies found no significant differences between iCT and postoperative MRI, the current gold standard. Further prospective studies are warranted to test the elimination of postoperative MRI when this system is used.

High resolution transcranial acoustoelectric imaging of current densities from a directional deep brain stimulator

OBJECTIVE

New innovations in deep brain stimulation (DBS) enable directional current steering-allowing more precise electrical stimulation of the targeted brain structures for Parkinson's disease, essential tremor and other neurological disorders. While intra-operative navigation through MRI or CT approaches millimeter accuracy for placing the DBS leads, no existing modality provides feedback of the currents as they spread from the contacts through the brain tissue. In this study, we investigate transcranial acoustoelectric imaging (tAEI) as a new modality to non-invasively image and characterize current produced from a directional DBS lead. tAEI uses ultrasound (US) to modulate tissue resistivity to generate detectable voltage signals proportional to the local currents.

APPROACH

An 8-channel directional DBS lead (Infinity 6172ANS, Abbott Inc) was inserted inside three adult human skulls submerged in 0.9% NaCl. A 2.5 MHz linear array delivered US pulses through the transtemporal window and focused near the contacts on the lead, while a custom amplifier and acquisition system recorded the acoustoelectric (AE) interaction used to generate images.

MAIN RESULTS

tAEI detected monopolar current with stimulation pulses as short as 100 µs with an SNR ranging from 10-27 dB when using safe US pressure (mechanical indices  <0.78) and injected current of ~2 mA peak amplitude. Adjacent contacts were discernable along the length and within each ring of the lead with a mean radial separation between contacts of 2.10 and 1.34 mm, respectively.

SIGNIFICANCE

These results demonstrate the feasibility of tAEI for high resolution mapping of directional DBS currents using clinically-relevant stimulation parameters. This new modality may improve the accuracy for placing the DBS leads, guide calibration and programming, and monitor long-term performance of DBS for treatment of Parkinson's disease.

Development of a novel frameless skull-mounted ball-joint guide array for use in image-guided neurosurgery

OBJECTIVE

Successful convection-enhanced delivery of therapeutic agents to subcortical brain structures requires accurate cannula placement. Stereotactic guiding devices have been developed to accurately target brain nuclei. However, technologies remain limited by a lack of MRI compatibility, or by devices' size, making them suboptimal for direct gene delivery to brain parenchyma. The goal of this study was to validate the accuracy of a novel frameless skull-mounted ball-joint guide array (BJGA) in targeting the nonhuman primate (NHP) brain.

METHODS

Fifteen MRI-guided cannula insertions were performed on 9 NHPs, each targeting the putamen. Optimal trajectories were planned on a standard MRI console using 3D multiplanar baseline images. After cannula insertion, the intended trajectory was compared to the final trajectory to assess deviation (euclidean error) of the cannula tip.

RESULTS

The average cannula tip deviation was 1.18 ± 0.60 mm (mean ± SD) as measured by 2 independent reviewers. Topological analysis showed a superior, posterior, and rightward directional bias, and the intra- and interclass correlation coefficients were > 0.85, indicating valid and reliable intra- and interobserver evaluation.

CONCLUSIONS

The data demonstrate that the BJGA can be used to reliably target subcortical brain structures by using MRI guidance, with accuracy comparable to current frameless stereotactic systems. The size and versatility of the BJGA, combined with a streamlined workflow, allows for its potential applicability to a variety of intracranial neurosurgical procedures, and for greater flexibility in executing MRI-guided experiments within the NHP brain.

Microelectrode Recordings Validate the Clinical Visualization of Subthalamic-Nucleus Based on 7T Magnetic Resonance Imaging and Machine Learning for Deep Brain Stimulation Surgery

BACKGROUND

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a proven and effective therapy for the management of the motor symptoms of Parkinson's disease (PD). While accurate positioning of the stimulating electrode is critical for success of this therapy, precise identification of the STN based on imaging can be challenging. We developed a method to accurately visualize the STN on a standard clinical magnetic resonance imaging (MRI). The method incorporates a database of 7-Tesla (T) MRIs of PD patients together with machine-learning methods (hereafter 7 T-ML).

OBJECTIVE

To validate the clinical application accuracy of the 7 T-ML method by comparing it with identification of the STN based on intraoperative microelectrode recordings.

METHODS

Sixteen PD patients who underwent microelectrode-recordings guided STN DBS were included in this study (30 implanted leads and electrode trajectories). The length of the STN along the electrode trajectory and the position of its contacts to dorsal, inside, or ventral to the STN were compared using microelectrode-recordings and the 7 T-ML method computed based on the patient's clinical 3T MRI.

RESULTS

All 30 electrode trajectories that intersected the STN based on microelectrode-recordings, also intersected it when visualized with the 7 T-ML method. STN trajectory average length was 6.2 ± 0.7 mm based on microelectrode recordings and 5.8 ± 0.9 mm for the 7 T-ML method. We observed a 93% agreement regarding contact location between the microelectrode-recordings and the 7 T-ML method.

CONCLUSION

The 7 T-ML method is highly consistent with microelectrode-recordings data. This method provides a reliable and accurate patient-specific prediction for targeting the STN.