A Meta-Analysis of Medication Reduction and Motor Outcomes After Awake Versus Asleep Deep Brain Stimulation for Parkinson Disease

BACKGROUND AND OBJECTIVES

There remains significant debate regarding the performance of deep brain stimulation (DBS) procedures for Parkinson disease (PD) under local or general anesthesia. The aim of this meta-analysis was to compare the clinical outcomes between "asleep" DBS (general anesthesia) and "awake" DBS (local anesthesia) for PD.

METHODS

We conducted a comprehensive literature review of all published studies on DBS for PD following PRISMA guideline on PubMed and Cochrane library from January 2004 to April 2023. Inclusion criteria included cohort ≥15 patients, clinical outcomes data which included Unified Parkinson's Disease Rating Scale (UPDRS) score and levodopa equivalent daily dosage (LEDD), and ≥3 months of follow-up. Analysis was conducted using Stata software.

RESULTS

There were 18 articles that met inclusion criteria. On meta-analysis, there were no significant differences between awake or asleep DBS with regard to percent change in UPDRS III "off" med/"on" DBS condition ( P = .6) and LEDD score ( P = .99). On subgroup analysis, we found that the choice of target had no significant effect on improvement of UPDRS III ( P = 1.0) or LEDD ( P = .99) change for the asleep vs awake operative approach. There were also no statistically significant differences between microelectrode recording (MER) use and no MER use in postoperative UPDRS III ( P = 1.0) or LEDD improvement ( P = .90) between awake and asleep surgery.

CONCLUSION

There was no significant difference in the primary motor outcomes and LEDD improvement between asleep vs awake DBS. The variables of target selection and MER use had no statistically significant impact on outcome. We find that asleep techniques are both safe and effective compared with the awake technique.

General anesthesia versus local anesthesia for deep brain stimulation targeting of STN in Parkinson's disease: A systematic review and meta-analysis

BACKGROUND

Subthalamic nucleus deep brain stimulation (STN-DBS) is a viable therapeutic for advanced Parkinson's disease. However, the efficacy and safety of STN-DBS under local anesthesia (LA) versus general anesthesia (GA) remain controversial. This meta-analysis aims to compare them using an expanded sample size.

METHODS

The databases of Embase, Cochrane Library and Medline were systematically searched for eligible cohort studies published between 1967 and 2023. Clinical efficacy was assessed using either Unified Parkinson's Disease Rating Scale (UPDRS) section III scores or levodopa equivalent dosage requirements. Subgroup analyses were performed to assess complications (adverse effects related to stimulation, general neurological and surgical complications, and hardware-related complications).

RESULTS

Fifteen studies, comprising of 13 retrospective cohort studies and 2 prospective cohort studies, involving a total of 943 patients were included in this meta-analysis. The results indicate that there were no significant differences between the 2 groups with regards to improvement in UPDRS III score or postoperative levodopa equivalent dosage requirement. However, subgroup analysis revealed that patients who underwent GA with intraoperative imaging had higher UPDRS III score improvement compared to those who received LA with microelectrode recording (MER) (P = .03). No significant difference was found in the improvement of UPDRS III scores between the GA group and LA group with MER. Additionally, there were no notable differences in the incidence rates of complications between these 2 groups.

CONCLUSIONS

Our meta-analysis indicates that STN-DBS performed under GA or LA have similar clinical outcomes and complications. Therefore, GA may be a suitable option for patients with severe symptoms who cannot tolerate the procedure under LA. Additionally, the GA group with intraoperative imaging showed better clinical outcomes than the LA group with MER. A more compelling conclusion would require larger prospective cohort studies with a substantial patient population and extended long follow-up to validate.

Awake versus Asleep Anesthesia in Deep Brain Stimulation Surgery for Parkinson's Disease: A Systematic Review and Meta-Analysis

INTRODUCTION

Deep brain stimulation (DBS) is a well-established surgical therapy for patients with Parkinsons' Disease (PD). Traditionally, DBS surgery for PD is performed under local anesthesia, whereby the patient is awake to facilitate intraoperative neurophysiological confirmation of the intended target using microelectrode recordings. General anesthesia allows for improved patient comfort without sacrificing anatomic precision and clinical outcomes.

METHODS

We performed a systemic review and meta-analysis on patients undergoing DBS for PD. Published randomized controlled trials, prospective and retrospective studies, and case series which compared asleep and awake techniques for patients undergoing DBS for PD were included. A total of 19 studies and 1,900 patients were included in the analysis.

RESULTS

We analyzed the (i) clinical effectiveness - postoperative UPDRS III score, levodopa equivalent daily doses and DBS stimulation requirements. (ii) Surgical and anesthesia related complications, number of lead insertions and operative time (iii) patient's quality of life, mood and cognitive measures using PDQ-39, MDRS, and MMSE scores. There was no significant difference in results between the awake and asleep groups, other than for operative time, for which there was significant heterogeneity.

CONCLUSION

With the advent of newer technology, there is likely to have narrowing differences in outcomes between awake or asleep DBS. What would therefore be more important would be to consider the patient's comfort and clinical status as well as the operative team's familiarity with the procedure to ensure seamless transition and care.

A Systematic Review of Neurophysiology-Based Localization Techniques Used in Deep Brain Stimulation Surgery of the Subthalamic Nucleus

OBJECTIVE

This systematic review is conducted to identify, compare, and analyze neurophysiological feature selection, extraction, and classification to provide a comprehensive reference on neurophysiology-based subthalamic nucleus (STN) localization.

MATERIALS AND METHODS

The review was carried out using the methods and guidelines of the Kitchenham systematic review and provides an in-depth analysis on methods proposed on STN localization discussed in the literature between 2000 and 2021. Three research questions were formulated, and 115 publications were identified to answer the questions.

RESULTS

The three research questions formulated are answered using the literature found on the respective topics. This review discussed the technologies used in past research, and the performance of the state-of-the-art techniques is also reviewed.

CONCLUSION

This systematic review provides a comprehensive reference on neurophysiology-based STN localization by reviewing the research questions other new researchers may also have.

Fundamentals of deep brain stimulation for Parkinson's disease in clinical practice: part 2

The field of neuromodulation has evolved significantly over the past decade. Developments include novel indications and innovations of hardware, software, and stimulation techniques leading to an expansion in scope and role of these techniques as powerful therapeutic interventions. In this review, which is the second part of an effort to document and integrate the basic fundamentals and recent successful developments in the field, we will focus on classic paradigms for electrode placement as well as new exploratory targets, mechanisms of neuromodulation using this technique and new developments, including focused ultrasound driven ablative procedures.

Susceptibility-Weighted MRI Approximates Intraoperative Microelectrode Recording During Deep Brain Stimulation of the Subthalamic Nucleus for Parkinson's Disease

BACKGROUND

Deep brain stimulation of the subthalamic nucleus (STN-DBS) for Parkinson's disease can be performed with intraoperative neurophysiological and radiographic guidance. Conventional T2-weighted magnetic resonance imaging sequences, however, often fail to provide definitive borders of the STN. Novel magnetic resonance imaging sequences, such as susceptibility-weighted imaging (SWI), might better localize the STN borders and facilitate radiographic targeting. We compared the radiographic location of the dorsal and ventral borders of the STN using SWI with intraoperative microelectrode recording (MER) during awake STN-DBS for Parkinson's disease.

METHODS

Thirteen consecutive patients who underwent placement of 24 STN-DBS leads for Parkinson's disease were analyzed retrospectively. Preoperative targeting was performed with SWI, and MER data were obtained from intraoperative electrophysiology records. The boundaries of the STN on SWI were identified by a blinded investigator.

RESULTS

The final electrode position differed significantly from the planned coordinates in depth but not in length or width, indicating that MER guided the final electrode depth. When we compared the boundaries of the STN by MER and SWI, SWI accurately predicted the entry into the STN but underestimated the length and ventral boundary of the STN by 1.2 mm. This extent of error approximates the span of a DBS contact and could affect the placement of directional contacts within the STN.

CONCLUSIONS

MER might continue to have a role in STN-DBS. This could potentially be mitigated by further refinement of imaging protocols to better image the ventral boundary of the STN.

Factors influencing the reliability of intraoperative testing in deep brain stimulation for Parkinson's disease

BACKGROUND

Several meta-analyses comparing the outcome of awake versus asleep deep brain stimulation procedures could not reveal significant differences concerning the postoperative improvement of motor symptoms. Only rarely information on the procedural details is provided for awake operations and how often somnolence and disorientation occurred, which might hamper the reliability of intraoperative clinical testing. The aim of our study was to investigate possible influencing factors on the occurrence of somnolence and disorientation in awake DBS procedures.

METHODS

We retrospectively analyzed 122 patients with Parkinson's disease having received implantation of a DBS system at our centre. Correlation analyses were performed for the duration of disease prior to surgery, number of microelectrode trajectories, AC-PC-coordinates of the planned target, UPDRS-scores, intraoperative application of sedative drugs, duration of the surgical procedure, perioperative application of apomorphine, and the preoperative L-DOPA equivalence dosage with the occurrence of intraoperative somnolence and disorientation.

RESULTS

Patients with intraoperative somnolence were significantly older (p=0.039). Increased duration of the DBS procedure (p=0.020), delayed start of the surgery (p=0.049), higher number of MER trajectories (p=0.041), and the patients' % UPDRS improvement (p=0.046) also correlated with the incidence of intraoperative somnolence. We identified the main contributing factor to intraoperative somnolence as the use of sedative drugs applied during skin incision and burr hole trepanation (p=0.019). Perioperatively applied apomorphine could reduce the occurrence of somnolent phases during the operation (p=0.026).

CONCLUSION

Several influencing factors were found to seemingly increase the risk of intraoperative somnolence and disorientation, while the use of sedative drugs seems to be the main contributing factor. We argue that awake DBS procedures should omit the use of sedatives for best clinical outcome. When reporting on awake DBS surgery these factors should be considered and adjusted for, to permit reliable interpretation and comparison of DBS study results.

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.

Molecular Mechanisms and Therapeutic Strategies for Levodopa-Induced Dyskinesia in Parkinson's Disease: A Perspective Through Preclinical and Clinical Evidence

Parkinson's disease (PD) is the second leading neurodegenerative disease that is characterized by severe locomotor abnormalities. Levodopa (L-DOPA) treatment has been considered a mainstay for the management of PD; however, its prolonged treatment is often associated with abnormal involuntary movements and results in L-DOPA-induced dyskinesia (LID). Although LID is encountered after chronic administration of L-DOPA, the appearance of dyskinesia after weeks or months of the L-DOPA treatment has complicated our understanding of its pathogenesis. Pathophysiology of LID is mainly associated with alteration of direct and indirect pathways of the cortico-basal ganglia-thalamic loop, which regulates normal fine motor movements. Hypersensitivity of dopamine receptors has been involved in the development of LID; moreover, these symptoms are worsened by concurrent non-dopaminergic innervations including glutamatergic, serotonergic, and peptidergic neurotransmission. The present study is focused on discussing the recent updates in molecular mechanisms and therapeutic approaches for the effective management of LID in PD patients.

The Role of Microelectrode Recording and Stereotactic Computed Tomography in Verifying Lead Placement During Awake MRI-Guided Subthalamic Nucleus Deep Brain Stimulation for Parkinson's Disease

BACKGROUND

Bilateral deep brain stimulation of the subthalamic nucleus (STN-DBS) has become a cornerstone in the advanced treatment of Parkinson's disease (PD). Despite its well-established clinical benefit, there is a significant variation in the way surgery is performed. Most centers operate with the patient awake to allow for microelectrode recording (MER) and intraoperative clinical testing. However, technical advances in MR imaging and MRI-guided surgery raise the question whether MER and intraoperative clinical testing still have added value in DBS-surgery.

OBJECTIVE

To evaluate the added value of MER and intraoperative clinical testing to determine final lead position in awake MRI-guided and stereotactic CT-verified STN-DBS surgery for PD.

METHODS

29 consecutive patients were analyzed retrospectively. Patients underwent awake bilateral STN-DBS with MER and intraoperative clinical testing. The role of MER and clinical testing in determining final lead position was evaluated. Furthermore, interobserver variability in determining the MRI-defined STN along the planned trajectory was investigated. Clinical improvement was evaluated at 12 months follow-up and adverse events were recorded.

RESULTS

98% of final leads were placed in the central MER-track with an accuracy of 0.88±0.45 mm. Interobserver variability of the MRI-defined STN was 0.84±0.09. Compared to baseline, mean improvement in MDS-UPDRS-III, PDQ-39 and LEDD were 26.7±16.0 points (54%) (p < 0.001), 9.0±20.0 points (19%) (p = 0.025), and 794±434 mg/day (59%) (p < 0.001) respectively. There were 19 adverse events in 11 patients, one of which (lead malposition requiring immediate postoperative revision) was a serious adverse event.

CONCLUSION

MER and intraoperative clinical testing had no additional value in determining final lead position. These results changed our daily clinical practice to an asleep MRI-guided and stereotactic CT-verified approach.

The Role of Microelectrode Recording in Deep Brain Stimulation Surgery for Parkinson's Disease: A Systematic Review and Meta-Analysis

BACKGROUND

STN-DBS is a cornerstone in the treatment of advanced Parkinson's disease (PD). The traditional approach is to use an awake operative technique with microelectrode recording (MER). However, more centers start using an asleep MRI-guided technique without MER.

OBJECTIVE

We systematically reviewed the literature to compare STN-DBS surgery with and without MER for differences in clinical outcome.

METHODS

We systematically searched PubMed, Embase, MEDLINE, and Web of Science databases for randomized clinical trials and consecutive cohort studies published between 01-01-2000 and 26-08-2021, that included at least 10 PD patients who had received bilateral STN-DBS.

RESULTS

2,129 articles were identified. After abstract screening and full-text review, 26 studies were included in the final analysis, comprising a total of 34 study groups (29 MER and 5 non-MER). The standardized mean difference (SMD) in change in motor symptoms between baseline (OFF medication) and 6-24 months follow-up (OFF medication and ON stimulation) was 1.64 for the MER group and 1.87 for non-MER group (p = 0.59). SMD in change in levodopa equivalent daily dose (LEDD) was 1.14 for the MER group and 0.65 for non-MER group (p < 0.01). Insufficient data were available for comparative analysis of PDQ-39 and complications.

CONCLUSION

The change in motor symptoms from baseline to follow-up did not differ between studies that used MER and those that did not. The postoperative reduction in LEDD from baseline to follow-up was greater in the MER-group. In the absence of high-quality studies comparing both methods, there is a clear need for a well-designed comparative trial.

[Deep brain stimulation of the subthalamic nucleus for parkinson's disease: awake vs asleep]

BACKGROUND

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is known to be an effective and safe neurosurgical procedure for Parkinson's disease (PD). Traditionally, awake implantation of stimulation system is carried out using microelectrode registration and intraoperative stimulation. Development of neuroimaging technologies enables direct STN imaging. Therefore, asleep surgery without additional intraoperative verification is possible. This approach reduces surgery time and can potentially decrease the incidence of hemorrhagic and infectious complications. The advantages of one method or another are being discussed.

OBJECTIVE

To assess the benefits and limitations of various methods for DBS system implantation for bilateral STN stimulation, to study the issues of stereotaxic accuracy, efficiency and safety of asleep and awake electrode implantation into STN.

MATERIAL AND METHODS

We reviewed the articles published in the PubMed database. Searching algorithm included the following keywords: «asleep DBS», «Parkinson's disease», «subthalamic nucleus», «3T MRI», «SWI», «SWAN».

RESULTS

There were 31 articles devoted to asleep DBS of STN including 4 meta-analyses, 3 prospective controlled studies, 13 retrospective controlled studies and 11 studies without a control group.

CONCLUSION

Asleep implantation of electrodes for DBS of STN can be performed only after a clear imaging of STN boundaries with high-quality MRI.

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.

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.

Asleep Surgery May Improve the Therapeutic Window for Deep Brain Stimulation of the Subthalamic Nucleus

OBJECTIVE

The effect of anesthesia type in terms of asleep vs. awake deep brain stimulation (DBS) surgery on therapeutic window (TW) has not been investigated so far. The objective of the study was to investigate whether asleep DBS surgery of the subthalamic nucleus (STN) improves TW for both directional (dDBS) and omnidirectional (oDBS) stimulation in a large single-center population.

MATERIALS AND METHODS

A total of 104 consecutive patients with Parkinson's disease (PD) undergoing STN-DBS surgery (80 asleep and 24 awake) were compared regarding TW, therapeutic threshold, side effect threshold, improvement of Unified PD Rating Scale motor score (UPDRS-III) and degree of levodopa equivalent daily dose (LEDD) reduction.

RESULTS

Asleep DBS surgery led to significantly wider TW compared to awake surgery for both dDBS and oDBS. However, dDBS further increased TW compared to oDBS in the asleep group only and not in the awake group. Clinical efficacy in terms of UPDRS-III improvement and LEDD reduction did not differ between groups.

CONCLUSIONS

Our study provides first evidence for improvement of therapeutic window by asleep surgery compared to awake surgery, which can be strengthened further by dDBS. These results support the notion of preferring asleep over awake surgery but needs to be confirmed by prospective trials.

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.

Comparison of Intraoperative 3-Dimensional Fluoroscopy With Standard Computed Tomography for Stereotactic Frame Registration

BACKGROUND

Three-dimensional fluoroscopy via the O-arm (Medtronic, Dublin, Ireland) has been validated for intraoperative confirmation of successful lead placement in stereotactic electrode implantation. However, its role in registration and targeting has not yet been studied. After frame placement, many stereotactic neurosurgeons obtain a computed tomography (CT) scan and merge it with a preoperative magnetic resonance imaging (MRI) scan to generate planning coordinates; potential disadvantages of this practice include increased procedure time and limited scanner availability.

OBJECTIVE

To evaluate whether the second-generation O-arm (O2) can be used in lieu of a traditional CT scan to obtain accurate frame-registration scans.

METHODS

In 7 patients, a postframe placement CT scan was merged with preoperative MRI and used to generate lead implantation coordinates. After implantation, the fiducial box was again placed on the patient to obtain an O2 confirmation scan. Vector, scalar, and Euclidean differences between analogous X, Y, and Z coordinates from fused O2/MRI and CT/MRI scans were calculated for 33 electrode target coordinates across 7 patients.

RESULTS

Marginal means of difference for vector (X = -0.079 ± 0.099 mm; Y = -0.076 ± 0.134 mm; Z = -0.267 ± 0.318 mm), scalar (X = -0.146 ± 0.160 mm; Y = -0.306 ± 0.106 mm; Z = 0.339 ± 0.407 mm), and Euclidean differences (0.886 ± 0.190 mm) remained within the predefined equivalence margin differences of -2 mm and 2 mm.

CONCLUSION

This study demonstrates that O2 may emerge as a viable alternative to the traditional CT scanner for generating planning coordinates. Adopting the O2 as a perioperative tool may offer reduced transport risks, decreased anesthesia time, and greater surgical efficiency.

Relative Contribution of Magnetic Resonance Imaging, Microelectrode Recordings, and Awake Test Stimulation in Final Lead Placement during Deep Brain Stimulation Surgery of the Subthalamic Nucleus in Parkinson's Disease

INTRODUCTION

For deep brain stimulation (DBS) surgery of the subthalamic nucleus (STN) in Parkinson's disease (PD), many centers employ visualization of the nucleus on magnetic resonance imaging (MRI), intraoperative microelectrode recordings (MER), and test stimulation in awake patients. The value of these steps is a subject for ongoing debate. In the current study, we determined the relative contribution of MRI targeting, multitrack MER, and awake test stimulation in final lead placement during STN DBS surgery for PD.

METHODS

Data on PD patients undergoing MRI-targeted STN DBS surgery with three-channel MER and awake test stimulation between February 2010 and January 2014 were analyzed to determine in which MER trajectory final leads were implanted and why this tract was chosen.

RESULTS

Seventy-six patients underwent implantation of 146 DBS leads. In 92% of the STN, the final leads were implanted in one of the three planned channels. In 6%, additional channels were needed. In 2%, surgery was aborted before final lead implantation due to anxiety or fatigue. The final leads were implanted in the channels with the longest STN MER signal trajectory in 60% of the STN (38% of the bilaterally implanted patients). This was the central channel containing the MRI target in 39% of the STN (18% bilaterally). The most frequently noted reasons why another channel than the central channel was chosen for final lead placement were (1) a lower threshold for side effects (54%) and (2) no or a too short trajectory of the STN MER signal (40%) in the central channel. The latter reason correlated with larger 2D (x and y) errors in our stereotactic method.

CONCLUSIONS

STN DBS leads were often not implanted in the MRI-planned trajectory or in the trajectory with the longest STN MER signal. Thresholds for side effects during awake test stimulation were decisive for final target selection in the majority of patients.

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.

Comparison of Awake and Asleep Deep Brain Stimulation for Parkinson's Disease: A Detailed Analysis Through Literature Review

OBJECTIVES

Deep brain stimulation (DBS) for Parkinson's disease (PD) has been applied to clinic for approximately 30 years. The goal of this review is to explore the similarities and differences between "awake" and "asleep" DBS techniques.

METHODS

A comprehensive literature review was carried out to identify relevant studies and review articles describing applications of "awake" or "asleep" DBS for Parkinson's disease. The surgical procedures, clinical outcomes, costs and complications of each technique were compared in detail through literature review.

RESULTS

The surgical procedures of awake and asleep DBS surgeries rely upon different methods for verification of intended target acquisition. The existing research results demonstrated that the stereotactic targeting accuracy of lead placement obtained by either method is reliable. There were no significant differences in clinical outcomes, costs, or complications between the two techniques.

CONCLUSION

The surgical and clinical outcomes of asleep DBS for PD are comparable to those of awake DBS.

Frameless ROSA® Robot-Assisted Lead Implantation for Deep Brain Stimulation: Technique and Accuracy

BACKGROUND

Frameless robotic-assisted surgery is an innovative technique for deep brain stimulation (DBS) that has not been assessed in a large cohort of patients.

OBJECTIVE

To evaluate accuracy of DBS lead placement using the ROSA® robot (Zimmer Biomet) and a frameless registration.

METHODS

All patients undergoing DBS surgery in our institution between 2012 and 2016 were prospectively included in an open label single-center study. Accuracy was evaluated by measuring the radial error (RE) of the first stylet implanted on each side and the RE of the final lead position at the target level. RE was measured on intraoperative telemetric X-rays (group 1), on intraoperative O-Arm® (Medtronic) computed tomography (CT) scans (group 2), and on postoperative CT scans or magnetic resonance imaging (MRI) in both groups.

RESULTS

Of 144 consecutive patients, 119 were eligible for final analysis (123 DBS; 186 stylets; 192 leads). In group 1 (76 patients), the mean RE of the stylet was 0.57 ± 0.02 mm, 0.72 ± 0.03 mm for DBS lead measured intraoperatively, and 0.88 ± 0.04 mm for DBS lead measured postoperatively on CT scans. In group 2 (43 patients), the mean RE of the stylet was 0.68 ± 0.05 mm, 0.75 ± 0.04 mm for DBS lead measured intraoperatively; 0.86 ± 0.05 mm and 1.10 ± 0.08 mm for lead measured postoperatively on CT scans and on MRI, respectively No statistical difference regarding the RE of the final lead position was found between the different intraoperative imaging modalities and postoperative CT scans in both groups.

CONCLUSION

Frameless ROSA® robot-assisted technique for DBS reached submillimeter accuracy. Intraoperative CT scans appeared to be reliable and sufficient to evaluate the final lead position.

Deep brain stimulation outcomes in patients implanted under general anesthesia with frame-based stereotaxy and intraoperative MRI

OBJECTIVEThe authors' aim in this study was to evaluate placement accuracy and clinical outcomes in patients who underwent implantation of deep brain stimulation devices with the aid of frame-based stereotaxy and intraoperative MRI after induction of general anesthesia.METHODSThirty-three patients with movement disorders (27 with Parkinson's disease) underwent implantation of unilateral or bilateral deep brain stimulation systems (64 leads total). All patients underwent the implantation procedure with standard frame-based techniques under general anesthesia and without microelectrode recording. MR images were acquired immediately after the procedure and fused to the preoperative plan to verify accuracy. To evaluate clinical outcome, different scales were used to assess quality of life (EQ-5D), activities of daily living (Unified Parkinson's Disease Rating Scale [UPDRS] part II), and motor function (UPDRS part III during off- and on-medication and off- and on-stimulation states). Accuracy was assessed by comparing the coordinates (x, y, and z) from the preoperative plan and coordinates from the tip of the lead on intraoperative MRI and postoperative CT scans.RESULTSThe EQ-5D score improved or remained stable in 71% of the patients. When in the off-medication/on-stimulation state, all patients reported significant improvement in UPDRS III score at the last follow-up (p < 0.001), with a reduction of 25.2 points (46.3%) (SD 14.7 points and 23.5%, respectively). There was improvement or stability in the UPDRS II scores for 68% of the Parkinson's patients. For 2 patients, the stereotactic error was deemed significant based on intraoperative MRI findings. In these patients, the lead was removed and replaced after correcting for the error during the same procedure. Postoperative lead revision was not necessary in any of the patients. Based on findings from the last intraoperative MRI study, the mean difference between the tip of the electrode and the planned target was 0.82 mm (SD 0.5 mm, p = 0.006) for the x-axis, 0.67 mm (SD 0.5 mm, p < 0.001) for the y-axis, and 0.78 mm (SD 0.7 mm, p = 0.008) for the z-axis. On average, the euclidian distance was 1.52 mm (SD 0.6 mm). In patients who underwent bilateral implantation, accuracy was further evaluated comparing the first implanted side and the second implanted side. There was a significant mediolateral (x-axis) difference (p = 0.02) in lead accuracy between the first (mean 1.02 mm, SD 0.57 mm) and the second (mean 0.66 mm, SD 0.50 mm) sides. However, no significant difference was found for the y- and z-axes (p = 0.10 and p = 0.89, respectively).CONCLUSIONSFrame-based DBS implantation under general anesthesia with intraoperative MRI verification of lead location is safe, accurate, precise, and effective compared with standard implantation performed using awake intraoperative physiology. More clinical trials are necessary to directly compare outcomes of each technique.

Brain Shift and Pneumocephalus Assessment During Frame-Based Deep Brain Stimulation Implantation With Intraoperative Magnetic Resonance Imaging

BACKGROUND

Brain shift and pneumocephalus are major concerns regarding deep brain stimulation (DBS).

OBJECTIVE

To report the extent of brain shift in deep structures and pneumocephalus in intraoperative magnetic resonance imaging (MRI).

METHODS

Twenty patients underwent bilateral DBS implantation in an MRI suite. Volume of pneumocephalus, duration of procedure, and 6 anatomic landmarks (anterior commissure, posterior commissure, right fornix [RF], left fornix [LF], right putaminal point, and left putaminal point) were measured.

RESULTS

Pneumocephalus varied from 0 to 32 mL (median = 0.6 mL). Duration of the procedure was on average 195.5 min (118-268 min) and was not correlated with the amount of pneumocephalus. There was a significant posterior displacement of the anterior commissure (mean = -1.1 mm, P < .001), RF (mean = -0.6 mm, P < .001), LF (mean = -0.7 mm, P < .001), right putaminal point (mean = -0.9 mm, P = .001), and left putaminal point (mean = -1.0 mm, P = .001), but not of the posterior commissure (mean = 0.0 mm, P = .85). Both RF (mean = -.7 mm, P < .001) and LF (mean = -0.5 mm, P < .001) were posteriorly displaced after a right-sided burr hole. There was a correlation between anatomic landmarks displacement and pneumocephalus after 2 burr holes (rho = 0.61, P = .007), but not after 1 burr hole (rho = 0.16, P = .60).

CONCLUSION

Better understanding of how pneumocephalus displaces subcortical structures can significantly enhance our intraoperative decision making and overall targeting strategy.

Outcomes of Interventional-MRI Versus Microelectrode Recording-Guided Subthalamic Deep Brain Stimulation

In deep brain stimulation (DBS) of the subthalamic nucleus (STN) for Parkinson’s disease (PD), there is debate concerning the use of neuroimaging alone to confirm correct anatomic placement of the DBS lead into the STN, versus the use of microelectrode recording (MER) to confirm functional placement. We performed a retrospective study of a contemporaneous cohort of 45 consecutive patients who underwent either interventional-MRI (iMRI) or MER-guided DBS lead implantation. We compared radial lead error, motor and sensory side effect, and clinical benefit programming thresholds, and pre- and post-operative unified PD rating scale scores, and levodopa equivalent dosages. MER-guided surgery was associated with greater radial error compared to the intended target. In general, side effect thresholds during initial programming were slightly lower in the MER group, but clinical benefit thresholds were similar. No significant difference in the reduction of clinical symptoms or medication dosage was observed. In summary, iMRI lead implantation occurred with greater anatomic accuracy, in locations demonstrated to be the appropriate functional region of the STN, based on the observation of similar programming side effect and benefit thresholds obtained with MER. The production of equivalent clinical outcomes suggests that surgeon and patient preference can be used to guide the decision of whether to recommend iMRI or MER-guided DBS lead implantation to appropriate patients with PD.

Function-specific and Enhanced Brain Structural Connectivity Mapping via Joint Modeling of Diffusion and Functional MRI

A joint structural-functional brain network model is presented, which enables the discovery of function-specific brain circuits, and recovers structural connections that are under-estimated by diffusion MRI (dMRI). Incorporating information from functional MRI (fMRI) into diffusion MRI to estimate brain circuits is a challenging task. Usually, seed regions for tractography are selected from fMRI activation maps to extract the white matter pathways of interest. The proposed method jointly analyzes whole brain dMRI and fMRI data, allowing the estimation of complete function-specific structural networks instead of interactively investigating the connectivity of individual cortical/sub-cortical areas. Additionally, tractography techniques are prone to limitations, which can result in erroneous pathways. The proposed framework explicitly models the interactions between structural and functional connectivity measures thereby improving anatomical circuit estimation. Results on Human Connectome Project (HCP) data demonstrate the benefits of the approach by successfully identifying function-specific anatomical circuits, such as the language and resting-state networks. In contrast to correlation-based or independent component analysis (ICA) functional connectivity mapping, detailed anatomical connectivity patterns are revealed for each functional module. Results on a phantom (Fibercup) also indicate improvements in structural connectivity mapping by rejecting false-positive connections with insufficient support from fMRI, and enhancing under-estimated connectivity with strong functional correlation.

Clinical outcomes following awake and asleep deep brain stimulation for Parkinson disease

OBJECTIVE

Recent studies have shown similar clinical outcomes between Parkinson disease (PD) patients treated with deep brain stimulation (DBS) under general anesthesia without microelectrode recording (MER), so-called “asleep” DBS, and historical cohorts undergoing “awake” DBS with MER guidance. However, few studies include internal controls. This study aims to compare clinical outcomes after globus pallidus internus (GPi) and subthalamic nucleus (STN) DBS using awake and asleep techniques at a single institution.

METHODS

PD patients undergoing awake or asleep bilateral GPi or STN DBS were prospectively monitored. The primary outcome measure was stimulation-induced change in motor function off medication 6 months postoperatively, measured using the Unified Parkinson’s Disease Rating Scale part III (UPDRS-III). Secondary outcomes included change in quality of life, measured by the 39-item Parkinson’s Disease Questionnaire (PDQ-39), change in levodopa equivalent daily dosage (LEDD), stereotactic accuracy, stimulation parameters, and adverse events.

RESULTS

Six-month outcome data were available for 133 patients treated over 45 months (78 GPi [16 awake, 62 asleep] and 55 STN [14 awake, 41 asleep]). UPDRS-III score improvement with stimulation did not differ between awake and asleep groups for GPi (awake, 20.8 points [38.5%]; asleep, 18.8 points [37.5%]; p = 0.45) or STN (awake, 21.6 points [40.3%]; asleep, 26.1 points [48.8%]; p = 0.20) targets. The percentage improvement in PDQ-39 and LEDD was similar for awake and asleep groups for both GPi (p = 0.80 and p = 0.54, respectively) and STN cohorts (p = 0.85 and p = 0.49, respectively).

CONCLUSIONS

In PD patients, bilateral GPi and STN DBS using the asleep method resulted in motor, quality-of-life, and medication reduction outcomes that were comparable to those of the awake method.

Comparison of Awake vs. Asleep Surgery for Subthalamic Deep Brain Stimulation in Parkinson's Disease

BACKGROUND

Deep brain stimulation (DBS) surgery for Parkinson's disease (PD) is usually performed as awake surgery allowing sufficient intraoperative testing. Recently, outcomes after asleep surgery have been assumed comparable. However, direct comparisons between awake and asleep surgery are scarce.

OBJECTIVE

To investigate the difference between awake and asleep surgery comparing motor and nonmotor outcome after subthalamic nucleus (STN)-DBS in a large single center PD population.

METHODS

Ninety-six patients were retrospectively matched pairwise (48 asleep and 48 awake) and compared regarding improvement of Unified PD Rating Scale Motor Score (UPDRS-III), cognitive function, Levodopa-equivalent-daily-dose (LEDD), stimulation amplitudes, side effects, surgery duration, and complication rates. Routine testing took place at three months and one year postoperatively.

RESULTS

Chronic DBS effects (UPDRS-III without medication and with stimulation on [OFF/ON]) significantly improved UPDRS-III only after awake surgery at three months and in both groups one year postoperatively. Acute effects (percentage UPDRS-III reduction after activation of stimulation) were also significantly better after awake surgery at three months but not at one year compared to asleep surgery. UPDRS-III subitems "freezing" and "speech" were significantly worse after asleep surgery at three months and one year, respectively. LEDD was significantly lower after awake surgery only one week postoperatively. The other measures did not differ between groups.

CONCLUSIONS

Overall motor function improved faster in the awake surgery group, but the difference ceased after one year. However, axial subitems were worse in the asleep surgery group suggesting that worsening of axial symptoms was risked improving overall motor function. Awake surgery still seems advantageous for STN-DBS in PD, although asleep surgery may be considered with lower threshold in patients not suitable for awake surgery.

Awake versus Asleep Deep Brain Stimulation Surgery: Technical Considerations and Critical Review of the Literature

Advancements in neuroimaging have led to a trend toward direct, image-based targeting under general anesthesia without the use of microelectrode recording (MER) or intraoperative test stimulation, also referred to as “asleep” deep brain stimulation (DBS) surgery. Asleep DBS, utilizing imaging in the form of intraoperative computed tomography (iCT) or magnetic resonance imaging (iMRI), has demonstrated reliable targeting accuracy of DBS leads implanted within the globus pallidus and subthalamic nucleus while also improving clinical outcomes in patients with Parkinson’s disease. In lieu, of randomized control trials, retrospective comparisons between asleep and awake DBS with MER have shown similar short-term efficacy with the potential for decreased complications in asleep cohorts. In lieu of long-term outcome data, awake DBS using MER must demonstrate more durable outcomes with fewer stimulation-induced side effects and lead revisions in order for its use to remain justifiable; although patient-specific factors may also be used to guide the decision regarding which technique may be most appropriate and tolerable to the patient.

Intraoperative test stimulation versus stereotactic accuracy as a surgical end point: a comparison of essential tremor outcomes after ventral intermediate nucleus deep brain stimulation

OBJECTIVE Ventral intermediate nucleus deep brain stimulation (DBS) for essential tremor is traditionally performed with intraoperative test stimulation and conscious sedation, without general anesthesia (GA). Recently, the authors reported retrospective data on 17 patients undergoing DBS after induction of GA with standardized anatomical coordinates on T1-weighted MRI sequences used for indirect targeting. Here, they compare prospectively collected data from essential tremor patients undergoing DBS both with GA and without GA (non-GA). METHODS Clinical outcomes were prospectively collected at baseline and 3-month follow-up for patients undergoing DBS surgery performed by a single surgeon. Stereotactic, euclidean, and radial errors of lead placement were calculated. Functional (activities of daily living), quality of life (Quality of Life in Essential Tremor [QUEST] questionnaire), and tremor severity outcomes were compared between groups. RESULTS Fifty-six patients underwent surgery: 16 without GA (24 electrodes) and 40 with GA (66 electrodes). The mean baseline functional scores and QUEST summary indices were not different between groups (p = 0.91 and p = 0.59, respectively). Non-GA and GA groups did not differ significantly regarding mean postoperative percentages of functional improvement (non-GA, 47.9% vs GA, 48.1%; p = 0.96) or QUEST summary indices (non-GA, 79.9% vs GA, 74.8%; p = 0.50). Accuracy was comparable between groups (mean radial error 0.9 ± 0.3 mm for non-GA and 0.9 ± 0.4 mm for GA patients) (p = 0.75). The mean euclidean error was also similar between groups (non-GA, 1.1 ± 0.6 mm vs GA, 1.2 ± 0.5 mm; p = 0.92). No patient had an intraoperative complication, and the number of postoperative complications was not different between groups (non-GA, n = 1 vs GA, n = 10; p = 0.16). CONCLUSIONS DBS performed with the patient under GA to treat essential tremor is as safe and effective as traditional DBS surgery with intraoperative test stimulation while the patient is under conscious sedation without GA.

Comparison of General and Local Anesthesia for Deep Brain Stimulator Insertion: A Systematic Review

BACKGROUND

Subthalamic nucleus deep brain stimulation (STN-DBS) has become a standard treatment for many patients with Parkinson's disease (PD). The reported clinical outcome measures for procedures done under general anesthesia (GA) compared to traditional local anesthetic (LA) technique are quite heterogeneous and difficult to compare. The aim of this systematic review and metaanalysis was to determine whether the clinical outcome after STN-DBS insertion under GA is comparable to that under LA in patients with Parkinson's disease.

METHODS

The databases of Medline Embase, Cochrane library and Pubmed were searched for eligible studies (human trials, English language, published between 1946 and January of 2016). The primary outcome of this study was to assess the postoperative improvement in the symptoms, evaluated using either Unified Parkinson's Disease Rating Scale (UPDRS) scores or levodopa equivalent dosage (LEDD) requirement.

RESULTS

The literature searches yielded 395 citations and six retrospective cohort studies with a sample size of 455 (194 in GA and 261 in LA) were included in the analysis. Regarding the clinical outcomes, there were no significant differences in the postoperative Unified Parkinson's disease rating scale and levodopa equivalent drug dosage between the GA and the LA groups. Similarly, the adverse events and target accuracy were also comparable between the groups.

CONCLUSIONS

This systematic review and meta-analysis shows that currently there is no good quality data to suggest equivalence of GA to LA during STN-DBS insertion in patients with PD, with some factors trending towards LA. There is a need for a prospective randomized control trial to validate our results.

General Anesthesia versus Local Anesthesia in StereotaXY (GALAXY) for Parkinson's disease: study protocol for a randomized controlled trial

Background

The aim of the study is to investigate if deep brain stimulation (DBS) in the subthalamic nucleus (STN) for Parkinson’s disease (PD) under general anesthesia further improves outcome by lessening postoperative cognitive, mood, and behavioral adverse effects; shorten surgical time and hospital admittance; and produce comparable symptomatic and functional improvement to surgery under local anesthesia.

Methods/design

The study will be a single-center, prospective, randomized, open-label, blinded endpoint trial comparing DBS under general anesthesia with DBS under local anesthesia. The primary outcome measure is a composite score of the postoperative cognitive, mood, and behavioral adverse effects and will be measured 6 months after surgery. The secondary outcome measures consist of changes in motor symptoms, adverse effects of stimulation and surgical complications, surgical time, functional health, quality of life, patient satisfaction with the outcome of treatment, patient evaluation of the burden of therapy, and medication. A total of 110 patients with advanced PD who are candidates for DBS will be randomized during a 2.5-year period.

Discussion

The aim of this trial is to further enhance the effectiveness of DBS treatment in PD while reducing the burden of DBS surgery by studying if DBS surgery under general anesthesia results in less cognitive, mood, and behavioral adverse effects compared with surgery under local anesthesia.

Trial registration

Netherlands Trial Register, NTR5809. Registered on 23 April 2016.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2136-8) contains supplementary material, which is available to authorized users.

"Asleep" Deep Brain Stimulation Surgery: A Critical Review of the Literature

OBJECTIVE

Although performing deep brain stimulation (DBS) with the patient under general anesthesia without microelectrode recording (MER) or intraoperative test stimulation (ITS) for movement disorders ("asleep" DBS) has become increasingly popular, its feasibility is based on the untested assumption that stereotactic accuracy correlates with positive clinical outcomes. To investigate outcomes after asleep DBS without MER or neurophysiological testing, we reviewed the medical literature on the topic.

METHODS

We searched PubMed to identify all studies reporting clinical outcomes for patients who underwent DBS without MER or ITS for Parkinson disease (PD) or essential tremor (ET).

RESULTS

We identified 9 studies with level 3b (n = 3) or level 4 evidence (n = 6). Eight PD studies (220 patients) reported asleep placement of 431 electrodes (341 subthalamic nucleus, 90 globus pallidus interna). Unified Parkinson Disease Rating Scale motor examination-III scores for 208 patients demonstrated significant improvement (40.2%-65%) at 6-12 months. The levodopa equivalent daily dose for 115 patients was significantly reduced (14%-49.3%) at 6-12 months in 103 patients. Two studies with a comparison cohort undergoing "awake" DBS with MER found no differences in postoperative Unified Parkinson Disease Rating Scale-III improvement or levodopa equivalent daily dose reduction. One study of asleep DBS for ET found no difference in functional outcomes between 17 patients undergoing asleep ventral intermediate nucleus DBS and 40 patients undergoing awake placement with ITS.

CONCLUSIONS

Initial evidence suggests that asleep DBS can be performed safely for PD and ET with good clinical outcomes. Long-term follow-up, larger cohorts, and double-armed studies are needed to validate these initial results.

Can We Rely on Susceptibility-Weighted Imaging for Subthalamic Nucleus Identification in Deep Brain Stimulation Surgery?

BACKGROUND

Susceptibility-weighted imaging (SWI) offers significantly improved visibility of the subthalamic nucleus (STN) compared with traditional T2-weighted imaging. However, it is unknown whether the representation of the nucleus on SWI corresponds to the neurophysiological location of the STN.

OBJECTIVE

To determine the correlation between the intraoperative electrophysiological activity of the STN and the representation of the nucleus on different magnetic resonance imaging (MRI) sequences used for deep brain stimulation target planning.

METHODS

At stereotactic target depth, microelectrode recordings (MERs) of typical STN neuronal activity were mapped on 3 different preoperative MRI sequences: 1.5-T SWI, 1.5-T T2-weighted, and 3-T T2-weighted MRI. For each MRI sequence, it was determined whether the MER signal was situated inside or outside the contour of the STN.

RESULTS

A total of 196 MER tracks in 34 patients were evaluated. In 165 tracks (84%), typical electrophysiological STN activity was measured. MER activity was situated more consistently inside hypointense STN contour representation on 1.5- and 3-T T2-weighted images compared with SWI (99% and 100% vs 79%, respectively). The 21% incongruence of electrophysiological STN activity outside the STN contour on SWI was seen almost exclusively in the anterior and lateral microelectrode channels.

CONCLUSION

STN representation on SWI does not correspond to electrophysiological STN borders. SWI does not correctly display the lateral part of the STN. When aiming to target the superolateral sensorimotor part of the STN during deep brain stimulation surgery, SWI does not offer an advantage but a disadvantage compared with conventional T2. Future research is needed to determine whether these findings may also apply for high-field SWI.

Current Topics in Deep Brain Stimulation for Parkinson Disease

There is a long history of surgical treatment for Parkinson disease (PD). After pioneering trials and errors, the current primary surgical treatment for PD is deep brain stimulation (DBS). DBS is a promising treatment option for patients with medically refractory PD. However, there are still many problems and controversies associated with DBS. In this review, we discuss current issues in DBS for PD, including patient selection, clinical outcomes, complications, target selection, long-term outcomes, management of axial symptoms, timing of surgery, surgical procedures, cost-effectiveness, and new technology.

“Asleep” deep brain stimulation for essential tremor

OBJECT

Deep brain stimulation (DBS) performed under general anesthesia (“asleep” DBS) has not been previously reported for essential tremor. This is in part due to the inability to visualize the target (the ventral intermediate nucleus [VIM]) on MRI. The authors evaluate the efficacy of this asleep technique in treating essential tremor by indirect VIM targeting.

METHODS

The authors retrospectively reviewed consecutive cases of initial DBS for essential tremor performed by a single surgeon. DBS was performed with patients awake (n = 40, intraoperative test stimulation without microelectrode recording) or asleep (n = 17, under general anesthesia). Targeting proceeded with standardized anatomical coordinates on preoperative MRI. Intraoperative CT was used for stereotactic registration and lead position confirmation. Functional outcomes were evaluated with pre- and postoperative Bain and Findley Tremor Activities of Daily Living scores.

RESULTS

A total of 29 leads were placed in asleep patients, and 60 were placed in awake patients. Bain and Findley Tremor Activities of Daily Living Questionnaire scores were not significantly different preoperatively for awake versus asleep cohorts (p = 0.2). The percentage of postoperative improvement was not significantly different between asleep (48.6%) and awake (45.5%) cohorts (p = 0.35). Euclidean error (mm) was higher for awake versus asleep patients (1.7 ± 0.8 vs 1.2 ± 0.4, p = 0.01), and radial error (mm) trended higherfor awake versus asleep patients (1.3 ± 0.8 vs 0.9 ± 0.5, p = 0.06). There were no perioperative complications.

CONCLUSIONS

In the authors’ initial experience, asleep VIM DBS for essential tremor without intraoperative test stimulation can be performed safely and effectively.