Risk of surgical delivery to deep nuclei: a meta-analysis

Cerebral Intraparenchymal Hemorrhage due to Implantation of Electrodes for Deep Brain Stimulation: Insights from a Large Single-Center Retrospective Cross-Sectional Analysis

Cerebral intraparenchymal hemorrhage due to electrode implantation (CIPHEI) is a rare but serious complication of deep brain stimulation (DBS) surgery. This study retrospectively investigated a large single-center cohort of DBS implantations to calculate the frequency of CIPHEI and identify patient- and procedure-related risk factors for CIPHEI and their potential interactions. We analyzed all DBS implantations between January 2013 and December 2021 in a generalized linear model for binomial responses using bias reduction to account for sparse sampling of CIPHEIs. As potential risk factors, we considered age, gender, history of arterial hypertension, level of invasivity, types of micro/macroelectrodes, and implanted DBS electrodes. If available, postoperative coagulation and platelet function were exploratorily assessed in CIPHEI patients. We identified 17 CIPHEI cases across 839 electrode implantations in 435 included procedures in 418 patients (3.9%). Exploration and cross-validation analyses revealed that the three-way interaction of older age (above 60 years), high invasivity (i.e., use of combined micro/macroelectrodes), and implantation of directional DBS electrodes accounted for 82.4% of the CIPHEI cases. Acquired platelet dysfunction was present only in one CIPHEI case. The findings at our center suggested implantation of directional DBS electrodes as a new potential risk factor, while known risks of older age and high invasivity were confirmed. However, CIPHEI risk is not driven by the three factors alone but by their combined presence. The contributions of the three factors to CIPHEI are hence not independent, suggesting that potentially modifiable procedural risks should be carefully evaluated when planning DBS surgery in patients at risk.

Does Temporary Externalization of Electrodes After Deep Brain Stimulation Surgery Result in a Higher Risk of Infection?

OBJECTIVES

Deep brain stimulation (DBS) is a well-established surgical therapy for movement disorders that comprises implantation of stimulation electrodes and a pacemaker. These procedures can be performed separately, leaving the possibility of externalizing the electrodes for local field potential recording or testing multiple targets for therapeutic efficacy. It is still debated whether the temporary externalization of DBS electrodes leads to an increased risk of infection. We therefore aimed to assess the risk of infection during and after lead externalization in DBS surgery.

MATERIALS AND METHODS

In this retrospective study, we analyzed a consecutive series of 624 DBS surgeries, including 266 instances with temporary externalization of DBS electrodes for a mean of 6.1 days. Patients were available for follow-up of at least one year, except in 15 instances. In 14 patients with negative test stimulation, electrodes were removed. All kinds of infections related to implantation of the neurostimulation system were accounted for.

RESULTS

Overall, infections occurred in 22 of 624 surgeries (3.5%). Without externalization of electrodes, infections were noted after 7 of 358 surgeries (2.0%), whereas with externalization, 15 of 252 infections were found (6.0%). This difference was significant (p = 0.01), but it did not reach statistical significance when comparing groups within different diagnoses. The rate of infection with externalized electrodes was highest in psychiatric disorders (9.1%), followed by Parkinson's disease (7.3%), pain (5.7%), and dystonia (5.5%). The duration of the externalization of the DBS electrodes was comparable in patients who developed an infection (6.1 ± 3.1 days) with duration in those who did not (6.0 ± 3.5 days).

CONCLUSIONS

Although infection rates were relatively low in our study, there was a slightly higher infection rate when DBS electrodes were externalized. On the basis of our results, the indication for electrode externalization should be carefully considered, and patients should be informed about the possibility of a higher infection risk when externalization of DBS electrodes is planned.

Essential Tremor - Deep Brain Stimulation vs. Focused Ultrasound

INTRODUCTION

Essential Tremor (ET) is one of the most common tremor syndromes typically presented as action tremor, affecting mainly the upper limbs. In at least 30-50% of patients, tremor interferes with quality of life, does not respond to first-line therapies and/or intolerable adverse effects may occur. Therefore, surgery may be considered.

AREAS COVERED

In this review, the authors discuss and compare unilateral ventral intermedius nucleus deep brain stimulation (VIM DBS) and bilateral DBS with Magnetic Resonance-guided Focused Ultrasound (MRgFUS) thalamotomy, which comprises focused acoustic energy generating ablation under real-time MRI guidance. Discussion includes their impact on tremor reduction and their potential complications. Finally, the authors provide their expert opinion.

EXPERT OPINION

DBS is adjustable, potentially reversible and allows bilateral treatments; however, it is invasive requires hardware implantation, and has higher surgical risks. Instead, MRgFUS is less invasive, less expensive, and requires no hardware maintenance. Beyond these technical differences, the decision should also involve the patient, family, and caregivers.

Accuracy, precision, and safety of stereotactic, frame-based, intraoperative MRI-guided and MRI-verified deep brain stimulation in 650 consecutive procedures

OBJECTIVE

Suboptimal lead placement is one of the most common indications for deep brain stimulation (DBS) revision procedures. Confirming lead placement in relation to the visible anatomical target with dedicated stereotactic imaging before terminating the procedure can mitigate this risk. In this study, the authors examined the accuracy, precision, and safety of intraoperative MRI (iMRI) to both guide and verify lead placement during frame-based stereotactic surgery.

METHODS

A retrospective analysis of 650 consecutive DBS procedures for targeting accuracy, precision, and perioperative complications was performed. Frame-based lead placement took place in an operating room equipped with an MRI machine using stereotactic images to verify lead placement before removing the stereotactic frame. Immediate lead relocation was performed when necessary. Systematic analysis of the targeting error was calculated.

RESULTS

Verification of 1201 DBS leads with stereotactic MRI was performed in 643 procedures and with stereotactic CT in 7. The mean ± SD of the final targeting error was 0.9 ± 0.3 mm (range 0.1-2.3 mm). Anatomically acceptable lead placement was achieved with a single brain pass for 97% (n = 1164) of leads; immediate intraoperative relocation was performed in 37 leads (3%) to obtain satisfactory anatomical placement. General anesthesia was used in 91% (n = 593) of the procedures. Hemorrhage was noted after 4 procedures (0.6%); 3 patients (0.4% of procedures) presented with transient neurological symptoms, and 1 experienced delayed cognitive decline. Two bleeds coincided with immediate relocation (2 of 37 leads, 5.4%), which contrasts with hemorrhage in 2 (0.2%) of 1164 leads implanted on the first pass (p = 0.0058). Three patients had transient seizures in the postoperative period. The seizures coincided with hemorrhage in 2 of these patients and with immediate lead relocation in the other. There were 21 infections (3.2% of procedures, 1.5% in 3 months) leading to hardware removal. Delayed (> 3 months) retargeting of 6 leads (0.5%) in 4 patients (0.6% of procedures) was performed because of suboptimal stimulation benefit. There were no MRI-related complications, no permanent motor deficits, and no deaths.

CONCLUSIONS

To the authors' knowledge, this is the largest series reporting the use of iMRI to guide and verify lead location during DBS surgery. It demonstrates a high level of accuracy, precision, and safety. Significantly higher hemorrhage was encountered when multiple brain passes were required for lead implantation, although none led to permanent deficit. Meticulous audit and calibration can improve precision and maximize safety.

Use of Bayesian decision analysis to maximize value in patient-centered randomized clinical trials in Parkinson's disease

A fixed one-sided significance level of 5% is commonly used to interpret the statistical significance of randomized clinical trial (RCT) outcomes. While it is necessary to reduce the false positive rate, the threshold used could be chosen quantitatively and transparently to specifically reflect patient preferences regarding benefit-risk tradeoffs as well as other considerations. How can patient preferences be explicitly incorporated into RCTs in Parkinson's disease (PD), and what is the impact on statistical thresholds for device approval? In this analysis, we apply Bayesian decision analysis (BDA) to PD patient preference scores elicited from survey data. BDA allows us to choose a sample size (n ) and significance level (α ) that maximizes the overall expected value to patients of a balanced two-arm fixed-sample RCT, where the expected value is computed under both null and alternative hypotheses. For PD patients who had previously received deep brain stimulation (DBS) treatment, the BDA-optimal significance levels fell between 4.0% and 10.0%, similar to or greater than the traditional value of 5%. Conversely, for patients who had never received DBS, the optimal significance level ranged from 0.2% to 4.4%. In both of these populations, the optimal significance level increased with the severity of the patients' cognitive and motor function symptoms. By explicitly incorporating patient preferences into clinical trial designs and the regulatory decision-making process, BDA provides a quantitative and transparent approach to combine clinical and statistical significance. For PD patients who have never received DBS treatment, a 5% significance threshold may not be conservative enough to reflect their risk-aversion level. However, this study shows that patients who previously received DBS treatment present a higher tolerance to accept therapeutic risks in exchange for improved efficacy which is reflected in a higher statistical threshold.

Complications of Deep Brain Stimulation for Parkinson Disease and Relationship between Micro-electrode tracks and hemorrhage: Systematic Review and Meta-Analysis

BACKGROUND

Deep brain stimulation is a common treatment for Parkinson's disease (PD). Despite strong efficacy in well-selected patients, complications can occur. Intraoperative micro-electrode recording (MER) can enhance efficacy by improving lead accuracy. However, there is controversy as to whether MER increases risk of hemorrhage.

OBJECTIVES

To provide a comprehensive systematic review and meta-analysis reporting complication rates from deep brain stimulation in PD. We also interrogate the association between hemorrhage and MER.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were implemented while querying the Pubmed, Embase, and Cochrane databases. All included studies were randomized controlled trials and prospective case series with 5 or more patients. Primary outcomes included rates of overall revision, infection, lead malposition, surgical site and wound complications, hardware-related complications, and seizure. The secondary outcome was the relationship between number of MER tracks and hemorrhage rate.

RESULTS

262 articles with 21,261 patients were included in the analysis. Mean follow-up was 25.8 months (range 0-133). Complication rates were: revision 4.9%, infection 4.2%, lead malposition 3.3%, surgical site complications 2.8%, hemorrhage 2.4%, hardware-related complications 2.4%, and seizure 1.9%. While hemorrhage rate did not increase with single-track MER (odds ratio, 3.49; P = 0.29), there was a significant non-linear increase with each additional track.

CONCLUSION

Infection and lead malposition were the most common complications. Hemorrhage risk increases with more than one MER track. These results highlight the challenge of balancing surgical accuracy and perioperative risk.

Complications Related to Deep Brain Stimulation Lead Implantation: A Single-Surgeon Case Series

BACKGROUND

Deep brain stimulation (DBS) is the mainstay of surgical treatment for movement disorders, yet previous studies have shown widely varying complication rates. Given the elective nature of DBS surgery, minimizing surgical complications is imperative.

OBJECTIVE

To evaluate short-term and long-term complications related to DBS lead implantation surgeries performed by an experienced surgeon and provide an updated benchmark comparison for other DBS centers and alternative therapies.

METHODS

A retrospective chart review of patients who underwent DBS lead implantation surgery by a single surgeon at our institution between 2012 and 2020 was conducted. Demographic and clinical data including surgical complications were collected. A Kaplan-Meier survival analysis was used to evaluate the cumulative risk of lead revision or removal over time. Associations between patient characteristics and various complications were evaluated.

RESULTS

Four hundred fifty-one DBS leads were placed in 255 patients. Thirteen leads and 11 patients required revision. In total, 3.6% (95% CI [1.3%-5.9%]) of patients required revision at 1 year and 4.8% (95% CI [1.9%-7.6%]) at 5 years, with per-lead revision rates of 2.3% (95% CI [0.9%-3.6%]) and 3.3% (95% CI [1.5%-5.1%]), respectively. Less common diagnoses such as Tourette syndrome, post-traumatic tremor, and cluster headache trended toward association with lead revision or removal.

CONCLUSION

DBS performed by an experienced surgeon is associated with extremely low complication rates.

Intraoperative microelectrode recording under general anesthesia guided subthalamic nucleus deep brain stimulation for Parkinson's disease: One institution's experience

Objective

Microelectrode recording (MER) guided subthalamic nucleus deep brain stimulation (STN-DBS) under local anesthesia (LA) is widely applied in the management of advanced Parkinson's disease (PD). Whereas, awake DBS under LA is painful and burdensome for PD patients. We analyzed the influence of general anesthesia (GA) on intraoperative MER, to assess the feasibility and effectiveness of GA in MER guided STN-DBS.

Methods

Retrospective analysis was performed on the PD patients, who underwent bilateral MER guided STN-DBS in Wuhan Union Hospital from July 2019 to December 2021. The patients were assigned to LA or GA group according to the anesthetic methods implemented. Multidimensional parameters, including MER signals, electrode implantation accuracy, clinical outcome and adverse events, were analyzed.

Results

A total of 40 PD patients were enrolled in this study, including 18 in LA group and 22 in GA group. There were no statistically significant differences in patient demographics and baseline characteristics between two groups. Although, the parameters of MER signal, including frequency, inter-spike interval (ISI) and amplitude, were obviously interfered under GA, the waveforms of MER signals were recognizable and shared similar characteristics with LA group. Both LA and GA could achieve effective electrode implantation accuracy and clinical outcome. They also shared similar adverse events postoperatively.

Conclusion

GA is viable and comparable to LA in MER guided STN-DBS for PD, regarding electrode implantation accuracy, clinical outcome and adverse events. Notably, GA is more friendly and acceptable to the patients who are incapable of enduring intraoperative MER under LA.

Deep Brain Stimulation Can Differentiate Subregions of the Human Subthalamic Nucleus Area by EEG Biomarkers

Introduction: Precise lead localization is crucial for an optimal clinical outcome of subthalamic nucleus (STN) deep brain stimulation (DBS) treatment in patients with Parkinson's disease (PD). Currently, anatomical measures, as well as invasive intraoperative electrophysiological recordings, are used to locate DBS electrodes. The objective of this study was to find an alternative electrophysiology tool for STN DBS lead localization.

Methods: Sixty-one postoperative electrophysiology recording sessions were obtained from 17 DBS-treated patients with PD. An intraoperative physiological method automatically detected STN borders and subregions. Postoperative EEG cortical activity was measured, while STN low frequency stimulation (LFS) was applied to different areas inside and outside the STN. Machine learning models were used to differentiate stimulation locations, based on EEG analysis of engineered features.

Results: A machine learning algorithm identified the top 25 evoked response potentials (ERPs), engineered features that can differentiate inside and outside STN stimulation locations as well as within STN stimulation locations. Evoked responses in the medial and ipsilateral fronto-central areas were found to be most significant for predicting the location of STN stimulation. Two-class linear support vector machine (SVM) predicted the inside (dorso-lateral region, DLR, and ventro-medial region, VMR) vs. outside [zona incerta, ZI, STN stimulation classification with an accuracy of 0.98 and 0.82 for ZI vs. VMR and ZI vs. DLR, respectively, and an accuracy of 0.77 for the within STN (DLR vs. VMR)]. Multiclass linear SVM predicted all areas with an accuracy of 0.82 for the outside and within STN stimulation locations (ZI vs. DLR vs. VMR).

Conclusions: Electroencephalogram biomarkers can use low-frequency STN stimulation to localize STN DBS electrodes to ZI, DLR, and VMR STN subregions. These models can be used for both intraoperative electrode localization and postoperative stimulation programming sessions, and have a potential to improve STN DBS clinical outcomes.

[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.

General Anesthesia vs Local Anesthesia in Microelectrode Recording-Guided Deep-Brain Stimulation for Parkinson Disease: The GALAXY Randomized Clinical Trial

Importance

It is unknown if there is a difference in outcome in asleep vs awake deep brain stimulation (DBS) of the subthalamic nucleus for advanced Parkinson disease.

Objective

To determine the difference in adverse effects concerning cognition, mood, and behavior between awake and asleep DBS favoring the asleep arm of the study.

Design, Setting, and Participants

This study was a single-center prospective randomized open-label blinded end point clinical trial. A total of 187 persons with Parkinson disease were referred for DBS between May 2015 to March 2019. Analysis took place from January 2016 to January 2020. The primary outcome follow-up visit was conducted 6 months after DBS.

Interventions

Bilateral subthalamic nucleus DBS was performed while the patient was asleep (under general anesthesia) in 1 study arm and awake in the other study arm. Both arms of the study used a frame-based intraoperative microelectrode recording technique to refine final target placement of the DBS lead.

Main Outcomes and Measures

The primary outcome variable was the between-group difference in cognitive, mood, and behavioral adverse effects as measured by a composite score. The secondary outcomes included the Movement Disorders Society Unified Parkinson's Disease Rating Scale, the patient assessment of surgical burden and operative time.

Results

A total of 110 patients were randomized to awake (local anesthesia; n = 56; mean [SD] age, 60.0 (7.4) years; 40 [71%] male) or to asleep (general anesthesia; n = 54; mean [SD] age, 61.3 [7.9] years; 38 [70%] male) DBS surgery. The 6-month follow-up visit was completed by 103 participants. The proportion of patients with adverse cognitive, mood, and behavioral effects on the composite score was 15 of 52 (29%) after awake and 11 of 51 (22%) after asleep DBS (odds ratio, 0.7 [95% CI, 0.3-1.7]). There was no difference in improvement in the off-medication Movement Disorders Society Unified Parkinson's Disease Rating Scale Motor Examination scores between groups (awake group: mean [SD], -27.3 [17.5] points; asleep group: mean [SD], -25.3 [14.3] points; mean difference, -2.0 [95% CI, -8.1 to 4.2]). Asleep surgery was experienced as less burdensome by patients and was 26 minutes shorter than awake surgery.

Conclusions and Relevance

There was no difference in the primary outcome of asleep vs awake DBS. Future large randomized clinical trials should examine some of the newer asleep based DBS technologies because this study was limited to frame-based microelectrode-guided procedures.

Trial Registration

trialregister.nl Identifier: NTR5809.

Estimating the Risk of Deep Brain Stimulation in the Modern Era: 2008 to 2020

BACKGROUND

Deep brain stimulation (DBS) was first approved by the United States Food and Drug Administration in 1997. Although the fundamentals of DBS remain the same, hardware, software, and imaging have evolved significantly.

OBJECTIVE

To test our hypothesis that the aggregate complication rate in the medical literature in the past 12 years would be lower than what is often cited based on early experience with DBS surgery.

METHODS

PubMed, PsycINFO, and EMBASE were queried for studies from 2008 to 2020 that included patients treated with DBS from 2007 to 2019. This yielded 34 articles that evaluated all complications of DBS surgery, totaling 2249 patients.

RESULTS

The overall complication rate in this study was 16.7% per patient. There was found to be a systemic complication rate of 0.89%, intracranial complication rate of 2.7%, neurological complication rate of 4.6%, hardware complication rate of 2.2%, and surgical site complication rate of 3.4%. The infection and erosion rate was 3.0%.

CONCLUSION

This review suggests that surgical complication rates have decreased since the first decade after DBS was first FDA approved. Understanding how to minimize complications from the inception of a technique should receive more attention.

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.

Asleep Deep Brain Stimulation in Patients With Isolated Dystonia: Stereotactic Accuracy, Efficacy, and Safety

OBJECTIVES

Lead placement for deep brain stimulation (DBS) is routinely performed using neuroimaging or microelectrode recording (MER). Recent studies have demonstrated that DBS under general anesthesia using an imaging-guided target technique ("asleep" DBS) can be performed accurately and effectively with lower surgery complication rates than the MER-guided target method under local anesthesia ("awake" DBS). This suggests that asleep DBS may be a more acceptable method. However, there is limited direct evidence focused on isolated dystonia using this method. Therefore, this study aimed to investigate the clinical outcomes and targeting accuracy in patients with dystonia who underwent asleep DBS.

MATERIALS AND METHODS

We examined 56 patients (112 leads) with isolated dystonia who underwent asleep DBS targeting in the globus pallidus internus (GPi) and subthalamic nucleus (STN). The Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) scores were assessed preoperatively and at 12-month follow-up (12 m-FU). The lead accuracy was evaluated by comparing the coordinates of the preoperative plan with those of the final electrode implantation location. Other measures analyzed included stimulation parameters and adverse events (AEs).

RESULTS

For both GPi and STN cohorts, mean BFMDRS motor scores were significantly lower at 12 m-FU (8.9 ± 10.9 and 4.6 ± 5.7 points) than at baseline (22.6 ± 16.4 and 16.1 ± 14.1 points, p < 0.001). The mean difference between the planned target and the distal contact of the leads was 1.33 ± 0.54 mm for the right brain electrodes and 1.50 ± 0.57 mm for the left, determined by Euclidian distance. No perioperative complications or AEs related to the device were observed during the complete follow-up. However, AEs associated with stimulation occurred in 12 and 6 patients in the GPi and STN groups, respectively.

CONCLUSIONS

Asleep DBS may be an accurate, effective, and safe method for treating patients with isolated dystonia regardless of the stimulation target.

Optimal target localisation and eight-year outcome for subthalamic stimulation in patients with Parkinson's disease

OBJECTIVE

Deep brain stimulation of the subthalamic nucleus (STN-DBS) is a useful therapy to improve motor functions and reduce dependence on medication in patients with Parkinson's disease (PD). The purpose of the study is to assess the long-term clinical outcomes of STN-DBS and to determine the optimal placement of electrodes that for the most positive outcomes.

METHODS

A consecutive series of 42 PD patients were evaluated using the Unified Parkinson's Disease Rating Scale (UPDRS) before and after STN-DBS lead implantation. Postoperatively, patients were evaluated during both the medication 'ON' period (medication suppressed symptoms) and the medication 'OFF' period (when medication failed to suppress symptoms), and the results were compared to the baseline values prior to surgery. Follow-up assessments, focusing on motor functions, were performed 1, 3, 5, and 8 years after the initial implantation surgery. The locations of electrodes were measured and compared against the clinical outcomes.

RESULTS

STN-DBS remarkably improved the UPDRS-II, -III, and -IV dyskinesia and motor fluctuation scores in the OFF-medication condition when compared to baseline values. In addition, the dose of levodopa needed to elicit an effect declined sharply in the OFF-medication condition. Over time, the axial signs progressively worsened even with continuous stimulation and a levodopa response. The location of electrodes correlated with the most beneficial outcomes was the dorsal STN margin.

CONCLUSIONS

Our results confirm that overall, stimulation-induced motor improvement is still evident after 8 years. However, the primary best outcome declines with the progressive loss of favourable axial signs.

Intracranial hemorrhage risk factors of deep brain stimulation for Parkinson's disease: a 2-year follow-up study

Objective

This study aimed to analyze the risk factors of intracranial hemorrhage (ICH) after deep brain stimulation (DBS) for idiopathic Parkinson’s disease (PD).

Methods

Patients who received DBS from March 2014 to December 2016 were retrospectively analyzed. The hemorrhage index was derived by combining the hemorrhagic volume and clinical manifestations of ICH. All patients with IHC were followed up for 2 years.

Results

Computed tomography showed 13 events of ICH in 11 patients (nine cases in the subthalamic nucleus), including eight cases with symptomatic hemorrhage (seven cases in the subthalamic nucleus). Hemorrhage was characterized by intracranial hematoma in the electrode puncture tract. Male sex and hypertension were significant risk factors for ICH. Hemorrhage in the preferred puncture side was significantly higher than that in the non-preferred puncture side. The mean hemorrhage index was 2.23 ± 0.83 in 11 patients, and no permanent neurological impairment was found during the 2-year follow-up. The effect of DBS on motor symptoms was similar in patients with and without ICH.

Conclusion

Male sex and hypertension are risk factors of ICH after DBS in PD. The risk of hemorrhage on the first puncture site is significantly higher than that on the second puncture site.

Role of deep brain stimulation therapy in the magnetic resonance-guided high-frequency focused ultrasound era: current situation and future prospects

Introduction: Deep brain stimulation (DBS) is a well-established treatment of movement disorders; but recently there has been an increasing trend toward the ablative procedure magnetic resonance-guided focused ultrasound (MRgFU). DBS is an efficient neuromodulatory technique but associated with surgical complications. MRIgFUS is an incision-free method that allows thermal lesioning, with fewer surgical complications but irreversible effects.Areas covered: We look at current and prospective aspects of both techniques. In DBS, appropriate patient selection, improvement in surgical expertise, target accuracy (preoperative and intraoperative imaging), neurophysiological recordings, and novel segmented leads need to be considered. However, increased number of older patients with higher comorbidities and risk of DBS complications (mainly intracranial hemorrhage, but also infections, hardware complications) make them not eligible for surgery. With MRgFUS, hemorrhage risks are virtually nonexistent, infection or hardware malfunction are eliminated, while irreversible side effects can appear.Expert commentary: Comparison of the efficacy and risks associated with these techniques, in combination with a growing aged population in developed countries with higher comorbidities and a preference for less invasive treatments, necessitates a review of the indications for movement disorders and the most appropriate treatment modalities.

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.

Infuse-as-you-go convective delivery to enhance coverage of elongated brain targets: technical note

OBJECTIVE

To develop and assess a convective delivery technique that enhances the effectiveness of drug delivery to nonspherical brain nuclei, the authors developed an occipital "infuse-as-you-go" approach to the putamen and compared it to the currently used transfrontal approach.

METHODS

Eleven nonhuman primates received a bilateral putamen injection of adeno-associated virus with 2 mM gadolinium-DTPA by real-time MR-guided convective perfusion via either a transfrontal (n = 5) or occipital infuse-as-you-go (n = 6) approach.

RESULTS

MRI provided contemporaneous assessment and monitoring of putaminal infusions for transfrontal (2 to 3 infusion deposits) and occipital infuse-as-you-go (stepwise infusions) putaminal approaches. The infuse-as-you-go technique was more efficient than the transfrontal approach (mean 35 ± 1.1 vs 88 ± 8.3 minutes [SEM; p < 0.001]). More effective perfusion of the postcommissural and total putamen was achieved with the infuse-as-you-go versus transfronatal approaches (100-µl infusion volumes; mean posterior commissural coverage 76.2% ± 5.0% vs 32.8% ± 2.9% [p < 0.001]; and mean total coverage 53.5% ± 3.0% vs 38.9% ± 2.3% [p < 0.01]).

CONCLUSIONS

The infuse-as-you-go approach, paralleling the longitudinal axis of the target structure, provides a more effective and efficient method for convective infusate coverage of elongated, irregularly shaped subcortical brain nuclei.

Ethical development of stem-cell-based interventions

The process of developing new and complex stem-cell-based therapeutics is incremental and requires decades of sustained collaboration among different stakeholders. In this Perspective, we address key ethical and policy challenges confronting the clinical translation of stem-cell-based interventions (SCBIs), including premature diffusion of SCBIs to clinical practice, assessment of risk in trials, obtaining valid informed consent for research participants, balanced and complete scientific reporting and public communications, regulation, and equitable access to treatment. We propose a way forward for translating these therapies with the above challenges in mind.

Is awake physiological confirmation necessary for DBS treatment of Parkinson's disease today? A comparison of intraoperative imaging, physiology, and physiology imaging-guided DBS in the past decade

BACKGROUND

Deep brain stimulation (DBS) is a well-established surgical therapy for Parkinson's disease (PD). Intraoperative imaging (IMG), intraoperative physiology (PHY) and their combination (COMB) are the three mainstream DBS guidance methods.

OBJECTIVE

To comprehensively compare the use of IMG-DBS, PHY-DBS and COMB-DBS in treating PD.

METHODS

PubMed, Embase, the Cochrane Library and OpenGrey were searched to identify PD-DBS studies reporting guidance techniques published between January 1, 2010, and May 1, 2018. We quantitatively compared the therapeutic effects, surgical time, target error and complication risk and qualitatively compared the patient experience, cost and technical prospects. A meta-regression analysis was also performed. This study is registered with PROSPERO, number CRD42018105995.

RESULTS

Fifty-nine cohorts were included in the main analysis. The three groups were equivalent in therapeutic effects and infection risks. IMG-DBS (p < 0.001) and COMB-DBS (p < 0.001) had a smaller target error than PHY-DBS. IMG-DBS had a shorter surgical time (p < 0.001 and p = 0.008, respectively) and a lower intracerebral hemorrhage (ICH) risk (p = 0.013 and p = 0.004, respectively) than PHY- and COMB-DBS. The use of intraoperative imaging and microelectrode recording correlated with a higher surgical accuracy (p = 0.018) and a higher risk of ICH (p = 0.049).

CONCLUSIONS

The comparison of COMB-DBS and PHY-DBS showed intraoperative imaging's superiority (higher surgical accuracy), while the comparison of COMB-DBS and IMG-DBS showed physiological confirmation's inferiority (longer surgical time and higher ICH risk). Combined with previous evidence, the use of intraoperative neuroimaging techniques should become a future trend.

Pallidal neurostimulation versus botulinum toxin injections in the treatment of cervical dystonia: protocol of a randomized, sham-controlled trial (StimTox-CD)

Background

Selective peripheral denervation via botulinum neurotoxin injections into dystonic muscles is the first-line treatment for cervical dystonia. Pallidal neurostimulation is a potent alternative, but currently restricted to patients failing on neurotoxin therapy. As botulinum neurotoxin is partially effective but often unsatisfactory in a relevant proportion of patients, earlier neurostimulation might be advantageous in providing stable symptom control and preventing disability. This trial intends to demonstrate, that pallidal neurostimulation is superior to neurotoxin injections in best clinical practice for controlling the symptoms of cervical dystonia and that it is safe in patients with a partial therapy response to peripheral denervation. We hypothesize a better outcome in everyday functioning and health-related quality of life of neurostimulated patients.

Methods

We aim to recruit 66 cervical dystonia patients into a double-blind comparison of pallidal neurostimulation versus botulinum neurotoxin type A. Eligible patients need ≥25% motor symptom reduction 4 weeks after a neurotoxin test injection, but are willing to undergo DBS surgery due to unsatisfactory symptom control. All participants will be implanted with a DBS system, and randomized into 2 groups: First group will receive effective neurostimulation and saline injections into dystonic muscles. Second group is treated with regular neurotoxin injections and undergoes a sham-stimulation. Primary outcome is the change in TWSTRS total score between baseline and 6 months of therapy. Secondary outcome parameters are corresponding changes in TWSTRS motor score, Tsui score, CDQ-24 and SF-36. Safety will be assessed by frequency and severity of reported adverse events. Statistical analysis includes intention-to-treat and per protocol populations, analysis based on imputation of missing values and analysis adjusting for differences in baseline TWSTRS. After 6 months of blinded treatment all patients will receive open-label neurostimulation and neurotoxin treatment as needed, and are followed up 48 weeks after randomization.

Perspective

We will assess if pallidal neurostimulation is a safe and effective alternative to selective peripheral denervation by botulinum toxin injections in cervical dystonia, which may be offered earlier in the course of disease based on patient preference. A positive study outcome would influence future treatment guidelines of cervical dystonia.

Trial registration

EudraCT registration number: 2016-001378-13.

Risk analysis of hemorrhage in stereo-electroencephalography procedures

OBJECTIVE

To examine the true incidence of hemorrhage related to stereo-electroencephalography (SEEG) procedures. To analyze risk factors associated with the presence of different types of hemorrhage in SEEG procedures.

METHODS

This was a retrospective, single-center observational study examining every SEEG implantation performed at our center from 2009 to 2017. This consisted of 549 consecutive SEEG implantations using a variety of stereotactic and imaging techniques. A hemorrhage grading system was applied by a blinded neuroradiologist to every postimplant and postexplant computed tomography (CT) scan. Hemorrhages were classified as asymptomatic or symptomatic based on neurologic deficit seen on examination. Statistical analysis included multivariate regression using relevant preoperative variables to predict the presence of hemorrhage.

RESULTS

One hundred five implantations (19.1%) had any type of hemorrhage seen on postimplant CT. Of these, 93 (16.9%) were asymptomatic and 12 (2.2%) were symptomatic, with 3 implantations (0.6%) resulting in either a permanent deficit (2, 0.4%) or death (1, 0.2%). Male sex, increased number of electrodes, and increasing age were associated with increased risk of postimplant hemorrhage on multivariate analysis. Increasing score in the grading system was related to a statistically significant increase in the likelihood of a symptomatic hemorrhage.

SIGNIFICANCE

Detailed examination of every postimplant CT reveals that the total hemorrhage rate appears higher than previously reported. Most of these hemorrhages are small and asymptomatic. Our grading system may be useful to risk stratify these hemorrhages and awaits prospective validation.

Peri-Lead Edema After Deep Brain Stimulation Surgery: A Poorly Understood but Frequent Complication

OBJECTIVE

Postoperative peri-lead edema (PLE) is a poorly understood complication of deep brain stimulation (DBS), which has been described sporadically in patients presenting with profound and often delayed symptoms. We performed a prospective evaluation of patients undergoing DBS to determine the frequency of and identify risk factors for PLE.

METHODS

Patients underwent DBS electrode placement by a single physician. Postoperative magnetic resonance imaging (MRI) was performed approximately 6 weeks after the operation in asymptomatic subjects and analyzed for presence of PLE. All symptomatic subjects underwent MRI at the time of presentation. Data regarding index disease, preoperative medical issues, operative technique, and intraoperative variables were collected and statistically analyzed.

RESULTS

A total of 191 leads were placed in 102 subjects; 15 patients (14.7%) demonstrated PLE. Seven patients (6.9%) presented with symptoms related to PLE, most often altered mental status or neurologic deficit. Many of the MRI findings were profound, with PLE sometimes several centimeters in diameter. No statistically significant difference was found between PLE-positive and normal subjects when analyzing multiple variables, including presence of vascular disease, hypertension, anticoagulant/antiplatelet use, electrode target, index disease, unilateral versus bilateral lead placement, number of brain penetrations, and presence or absence of microelectrode recording.

CONCLUSIONS

Patients with postoperative PLE can present with severe symptoms or can be asymptomatic and go undiagnosed. Because of the delayed-onset potential, PLE may be more common than previously reported. No clear risk factors have been identified; therefore, further studies and increased clinical vigilance are paramount for improving comprehension and possible prevention of PLE.

White Matter Changes Along the Electrode Lead in Patients Treated With Deep Brain Stimulation

Introduction: Deep brain stimulation (DBS) is an established treatment for various movement disorders. There is little data available about the potential damage to brain parenchyma through DBS treatment. The objective of this study was to investigate the occurrence of signal changes on magnetic resonance imaging (MRI) in patients treated with DBS.

Methods: We retrospectively analyzed MRI scans of 30 DBS patients (21 patients with Parkinson's disease, 3 patients with dystonia and 6 patients with tremor) that had undergone additional MRI scans after DBS surgery (ranging from 2 months to 8 years). Axial T2 sequences were analyzed by two raters using a standardized lesion mapping procedure.

Results: 26 out of 30 analyzed patients showed hyperintense white matter changes surrounding the DBS lead (mean volume = 2.43 ml). Lesions were prominent along the upper half of the electrode lead within the subcortical white matter, with no abnormalities along the lower lead. Their volume was significantly correlated to the time from surgery to MRI and to the number of microelectrodes used in surgery, but was independent from underlying disease (Parkinson's disease, dystonia, tremor), target structure (STN, GPi, VIM), demographical data, or cardiovascular risk factors.

Discussion: White matter changes along the electrode leads in DBS patients are a frequent finding. These changes seem to evolve with certain latency after surgery and might be radiologically classified as a gliosis. Our findings identify the number of intraoperatively used microelectrodes as a risk factor in the formation of gliosis. Therefore, mechanical damage at the time of surgery and an individual tissue response might contribute to their evolution. Further studies are needed to define the exact mechanisms and their clinical impact.

Awake versus asleep deep brain stimulation for Parkinson's disease: a critical comparison and meta-analysis

OBJECTIVE

No definitive comparative studies of the efficacy of 'awake' deep brain stimulation (DBS) for Parkinson's disease (PD) under local or general anaesthesia exist, and there remains significant debate within the field regarding differences in outcomes between these two techniques.

METHODS

We conducted a literature review and meta-analysis of all published DBS for PD studies (n=2563) on PubMed from January 2004 to November 2015. Inclusion criteria included patient number >15, report of precision and/or clinical outcomes data, and at least 6 months of follow-up. There were 145 studies, 16 of which were under general anaesthesia. Data were pooled using an inverse-variance weighted, random effects meta-analytic model for observational data.

RESULTS

There was no significant difference in mean target error between local and general anaesthesia, but there was a significantly less mean number of DBS lead passes with general anaesthesia (p=0.006). There were also significant decreases in DBS complications, with fewer intracerebral haemorrhages and infections with general anaesthesia (p<0.001). There were no significant differences in Unified Parkinson's Disease Rating Scale (UPDRS) Section II scores off medication, UPDRS III scores off and on medication or levodopa equivalent doses between the two techniques. Awake DBS cohorts had a significantly greater decrease in treatment-related side effects as measured by the UPDRS IV off medication score (78.4% awake vs 59.7% asleep, p=0.022).

CONCLUSIONS

Our meta-analysis demonstrates that while DBS under general anaesthesia may lead to lower complication rates overall, awake DBS may lead to less treatment-induced side effects. Nevertheless, there were no significant differences in clinical motor outcomes between the two techniques. Thus, DBS under general anaesthesia can be considered at experienced centres in patients who are not candidates for traditional awake DBS or prefer the asleep alternative.

Better to be in The Placebo Arm for Trials of Neurological Therapies?

Patients with progressive neurodegenerative diseases often pursue trial entry seeking to access cutting edge therapies. However, cutting edge therapies for neurodegenerative diseases tend to have higher adverse event rates and underperform placebo. This essay argues that patients seeking trial entry are probably better off, medically, by being assigned to the placebo arm. Because trials involve extra clinic visits and research procedures, patients may be still better off medically by skipping trial participation altogether. I close by arguing that the Neurology research community might better honor the contributions of research subjects by pressing sponsors to promptly publish the results of non-positive trials, minimizing the use of uneven randomization ratios that favor assignment to the investigational treatment, and by fostering systematic collection of data on the risk/benefit balance of trial participation.

Surgical treatments for essential tremor

INTRODUCTION

Essential tremor is the most common form of pathologic tremor. Surgical therapies disrupt tremorogenic oscillation in the cerebellothalamocortical pathway and are capable of abolishing severe tremor that is refractory to available pharmacotherapies. Surgical methods are raspidly improving and are the subject of this review. Areas covered: A PubMed search on 18 January 2018 using the query essential tremor AND surgery produced 839 abstracts. 379 papers were selected for review of the methods, efficacy, safety and expense of stereotactic deep brain stimulation (DBS), stereotactic radiosurgery (SRS), focused ultrasound (FUS) ablation, and radiofrequency ablation of the cerebellothalamocortical pathway. Expert commentary: DBS and SRS, FUS and radiofrequency ablations are capable of reducing upper extremity tremor by more than 80% and are far more effective than any available drug. The main research questions at this time are: 1) the relative safety, efficacy, and expense of DBS, SRS, and FUS performed unilaterally and bilaterally; 2) the relative safety and efficacy of thalamic versus subthalamic targeting; 3) the relative safety and efficacy of atlas-based versus direct imaging tractography-based anatomical targeting; and 4) the need for intraoperative microelectrode recordings and macroelectrode stimulation in awake patients to identify the optimum anatomical target. Randomized controlled trials are needed.

Clinical outcomes of asleep vs awake deep brain stimulation for Parkinson disease

Objective:

To compare motor and nonmotor outcomes at 6 months of asleep deep brain stimulation (DBS) for Parkinson disease (PD) using intraoperative imaging guidance to confirm electrode placement vs awake DBS using microelectrode recording to confirm electrode placement.

Methods:

DBS candidates with PD referred to Oregon Health & Science University underwent asleep DBS with imaging guidance. Six-month outcomes were compared to those of patients who previously underwent awake DBS by the same surgeon and center. Assessments included an “off”-levodopa Unified Parkinson’s Disease Rating Scale (UPDRS) II and III, the 39-item Parkinson's Disease Questionnaire, motor diaries, and speech fluency.

Results:

Thirty participants underwent asleep DBS and 39 underwent awake DBS. No difference was observed in improvement of UPDRS III (+14.8 ± 8.9 vs +17.6 ± 12.3 points, p = 0.19) or UPDRS II (+9.3 ± 2.7 vs +7.4 ± 5.8 points, p = 0.16). Improvement in “on” time without dyskinesia was superior in asleep DBS (+6.4 ± 3.0 h/d vs +1.7 ± 1.2 h/d, p = 0.002). Quality of life scores improved in both groups (+18.8 ± 9.4 in awake, +8.9 ± 11.5 in asleep). Improvement in summary index (p = 0.004) and subscores for cognition (p = 0.011) and communication (p < 0.001) were superior in asleep DBS. Speech outcomes were superior in asleep DBS, both in category (+2.77 ± 4.3 points vs −6.31 ± 9.7 points (p = 0.0012) and phonemic fluency (+1.0 ± 8.2 points vs −5.5 ± 9.6 points, p = 0.038).

Conclusions:

Asleep DBS for PD improved motor outcomes over 6 months on par with or better than awake DBS, was superior with regard to speech fluency and quality of life, and should be an option considered for all patients who are candidates for this treatment.

Clinicaltrials.gov identifier:

NCT01703598.

Classification of evidence:

This study provides Class III evidence that for patients with PD undergoing DBS, asleep intraoperative CT imaging–guided implantation is not significantly different from awake microelectrode recording–guided implantation in improving motor outcomes at 6 months.

Intra-operative micro-electrode recording in functional neurosurgery: Past, present, future

The field of functional neurosurgery has experienced a rise, fall and lastly a renaissance over the past 75years. Micro-electrode recording (MER) played a key role during this eventful journey. However, as the intra-operative MRI continues to evolve, a pertinent question about the utility of MER has been raised in recent years. In this article, we critically review these current controversies. The English literature is reviewed and the complex technique of MER is discussed in a simplified manner. The improvement of neuroimaging and its application in functional neurosurgery, especially in deep brain stimulation, is discussed. Finally, the current controversies and technical advances which can direct the future are reviewed. The results of existing meta-analyses addressing the controversies are summarized. Wide variations of pre-operative and intra-operative targeting methods have been described in the literature. Though functional neurosurgery is generally safe, complications do occur and multiple passes during MER can certainly add to the risk of inadvertent hemorrhage and infection. Additionally, the recent introduction of newer MRI modalities has ensured better delineation of the target. However, MER is still useful to address brain shift, for mapping of newer targets, for ablative surgeries and in centers without an intra-operative imaging facility. In the current scenario, it is nearly impossible to conduct a prospective study to decide the utility of MER. The importance of MER may further diminish in the future as a routine procedure, but its role as a gold standard procedure may still persist.

A detailed analysis of intracerebral hemorrhages in DBS surgeries

OBJECTIVES

Deep brain stimulation is nowadays a frequently performed surgery in patients with movement disorders, intractable epilepsy, and severe psychiatric disorders. The most feared complication of this surgery is an intracerebral hemorrhage due to the electrode placement, either for intraoperative electrophysiology (microelectrode recording) and/or implantation of the final electrode (macroelectrode). Here, we have investigated the risk of developing an intracerebral hemorrhage in our cohort of deep brain stimulation patients over a period of 15 years.

PATIENTS AND METHODS

We have collected demographic data and analyzed the effect of performing surgery with single-electrode versus multiple electrode guided DBS. The effect of using single-dose versus double-dose contrast enhanced MRI to visualize vessels for the electrode trajectory planning has been investigated as well.

RESULTS

We have found that the overall calculated risk of an intracerebral hemorrhage in our series was 1.81% per patient, 0.3% per recording electrode and 0.23% per brain insertion. While three out of four patients recovered without neurological deficits, there was one mortality in a patient with cardiovascular comorbidities. Statistical comparisons between the groups of single-electrode versus multiple electrode guided surgery and single-dose gadolinium versus double-dose contrast enhanced MRI revealed no significant differences. In addition, there was no meaningful correlation between the age at surgery and the risk of bleeding.

CONCLUSION

We have found that the risk of developing an intracerebral hemorrhage due to deep brain stimulation surgery is low. The clinical course of the patients with an intracerebral hemorrhage was generally favorable.

Surgical implantation of STN-DBS leads using intraoperative MRI guidance: technique, accuracy, and clinical benefit at 1-year follow-up

BACKGROUND

Improvement of surgical accuracy during DBS-lead implantation has been described recently, leading to "frameless" or "MRI-verified" techniques. However, combining a high-quality definition of the STN using intraoperative 1.5 MRI with the possibility to reduce errors due to co-registration and to monitor lead progression during surgical insertion while checking the absence of surgical complication is an appealing method. We report here surgical methodology, safety, application accuracy, and clinical benefit of STN-lead implantation under MRI guidance.

METHODS

Two patients with a severe PD state were treated by bilateral STN-DBS. Leads were implanted under general anesthesia using intraoperative MRI guidance (ClearPoint system). Lead implantation accuracy was measured on T1 axial images at the level of the target. Clinical improvement was measured on the pre- and post-UPDRS 3 scale at 1-year follow-up.

RESULTS

Surgery was safe and uneventful in both cases. Radial error was 0.36 (right) and 0.86 mm (left) in case 1, and 0.41 (right) and 0.14 mm (left) in case 2. No edema or hemorrhage were noticed.

CONCLUSIONS

Intraoperative MRI guidance allows DBS lead implantation with high accuracy and with great clinical efficacy. A larger cohort of patients is needed to confirm these initial results.

[Deep brain stimulation for Parkinson's disease: timing and patient selection]

Deep brain stimulation (DBS) is an effective and evidence-based treatment option for Parkinson's disease. Studies have shown that DBS has good and long-term effects on motor function and quality of life for patients in an advanced stage of the disease and that it is more effective than medical therapy alone. Moreover, a favorable effect of DBS could also be detected at an earlier stage of the disease. On the other hand, possible risks and side effects of the procedure need to be taken into consideration. These can manifest as procedure-related complications, such as bleeding and infections in addition to stimulation-associated phenomena, such as neuropsychiatric disorders and motor side effects. Despite the good effects of DBS important issues still need to be addressed which will be discussed in this article considering the results of several new randomized and controlled clinical studies. For patients with Parkinson's disease with early fluctuations and dyskinesia, DBS has been found to be superior to the best pharmaceutical treatment; therefore, DBS can be considered as a treatment option in the earlier course of the disease. The diagnostic evaluation and the exclusion of contraindications are crucial for patient selection. The choice of the target should be based on the individual symptoms in patients although the subthalamic nucleus (STN) can be considered the standard target. In every case an individual assessment of chances and risks must be conducted and realistic goals and reasonable expectations must be defined.

Titer and product affect the distribution of gene expression after intraputaminal convection-enhanced delivery

BACKGROUND

The efficacy and safety of intracerebral gene therapy for brain disorders like Parkinson's disease depends on the appropriate distribution of gene expression.

OBJECTIVES

To assess whether the distribution of gene expression is affected by vector titer and protein type.

METHODS

Four adult macaque monkeys seronegative for adeno-associated virus 5 (AAV5) received a 30-µl inoculation of a high- or a low-titer suspension of AAV5 encoding glial cell line-derived neurotrophic factor (GDNF) or green fluorescent protein (GFP) in the right and left ventral postcommissural putamen. The inoculations were conducted using convection-enhanced delivery and intraoperative MRI (IMRI).

RESULTS

IMRI confirmed targeting and infusion cloud irradiation from the catheter tip into the surrounding area. A postmortem analysis 6 weeks after surgery revealed GFP and GDNF expression ipsilateral to the injection site that had a titer-dependent distribution. GFP and GDNF expression was also observed in fibers in the substantia nigra (SN) pars reticulata (pr), demonstrating anterograde transport. Few GFP-positive neurons were present in the SN pars compacta (pc), possibly by direct retrograde transport of the vector. GDNF was present in many neurons of the SNpc and SNpr.

CONCLUSIONS

After controlling for target and infusate volume, the intracerebral distribution of the gene product was affected by the vector titer and product biology.

Differential effects of two MRI contrast agents on the integrity and distribution of rAAV2 and rAAV5 in the rat striatum

Intraoperative magnetic resonance imaging (MRI) has been proposed as a method to optimize intracerebral targeting and for tracking infusate distribution in gene therapy trials for nervous system disorders. We thus investigated possible effects of two MRI contrast agents, gadoteridol (Gd) and galbumin (Gab), on the distribution and levels of transgene expression in the rat striatum and their effect on integrity and stability of recombinant adeno-associated virus (rAAV) particles. MRI studies showed that contrast agent distribution did not predict rAAV distribution. However, green fluorescent protein (GFP) immunoreactivity revealed an increase in distribution of rAAV5-GFP, but not rAAV2-GFP, in the presence of Gd when compared with viral vector injected alone. In contrast, Gab increased the distribution of rAAV2-GFP not rAAV5-GFP. These observations pointed to a direct effect of infused contrast agent on the rAAV particles. Negative-stain electron microscopy (EM), DNAase treatment, and differential scanning calorimetry (DSC) were used to monitor rAAV2 and rAAV5 particle integrity and stability following contrast agent incubation. EMs of rAAV2-GFP and rAAV5-GFP particles pretreated with Gd appear morphologically similar to the untreated sample; however, Gab treatment resulted in surface morphology changes and aggregation. A compromise of particle integrity was suggested by sensitivity of the packaged genome to DNAase treatment following Gab incubation but not Gd for both vectors. However, neither agent significantly affected particle stability when analyzed by DSC. An increase in T m was observed for AAV2 in lactated Ringer's buffer. These results thus highlight potential interactions between MRI contrast agents and AAV that might affect vector distribution and stability, as well as the stabilizing effect of lactated Ringer's solution on AAV2.

Subthalamic neurostimulation for Parkinson's disease with early fluctuations: balancing the risks and benefits

Electrical stimulation of the subthalamic nucleus is an established treatment for patients with advanced Parkinson's disease with pharmacologically unresponsive fluctuations. Compared with pharmacological treatment, subthalamic neurostimulation significantly improves motor symptoms, particularly during the phases of poor response to drug treatment, and reduces the severity of dyskinesias. Importantly, it also significantly improves quality of life and other integral measures of disease severity. The treatment response can last for more than 10 years, although there is no evidence that levodopa-resistant symptoms are delayed by subthalamic neurostimulation. At present, the mean disease duration for patients at the time of implantation is 12 years. In a recent study (EARLYSTIM) in patients with a disease duration of 7·5 years and fluctuations for 1·5 years, similar improvements in clinical outcomes were reported. These findings suggest that neurostimulation of the subthalamic nucleus could be used earlier in the disease course for carefully selected patients if the benefits of the treatment are weighed against the surgical risks and the lifelong need for specialised care by an experienced team. As mobility is consistently improved during the times with poor mobility by reducing fluctuations and delaying levodopa-sensitive complications, we propose that this treatment changes the disease course.

Pathways of infusate loss during convection-enhanced delivery into the putamen nucleus

BACKGROUND

New strategies aiming to treat Parkinson's disease, such as delivery of trophic factors via protein infusion or gene transfer, depend upon localized intracerebral infusion, mainly into the putamen nucleus. Convection-enhanced delivery (CED) has been proposed as a method to improve intracerebral distribution of therapies. Yet analysis of controversial results during the clinical translation of these strategies suggests that intracerebral misdistribution of infusate may have affected the outcomes by limiting the amount of treatment into the target region.

OBJECTIVES

This study aimed to identify possible pathways of infusate loss and their relative impact in the success of targeted CED into the postcommissural ventral putamen nucleus.

METHODS

Thirteen adult macaque monkeys received intraputaminal CED infusions of 100 µl of 2.0 mM gadoteridol and bromophenol blue (0.16 mg/ml) solution at a rate of 1.0 µl/min under intraoperative magnetic resonance imaging (MRI) guidance. Quantitative maps of infusate concentration were computed at 10-min intervals throughout the procedure in a 3-Tesla MRI scanner. The fraction of tracer lost from the putamen as well as the path of loss were evaluated and quantified for each infusion.

RESULTS

All injections (total 22) were successfully placed in the ventral postcommissural putamen nucleus. Four major paths of infusate loss from the putamen were observed: overflow across putamen boundaries, perivascular flow along large blood vessels, backflow along the inserted catheter and catheter tract leakage into the vacated catheter tract upon catheter removal. Overflow loss was observed within the first 30 µl of infusion in all cases. Measurable tracer loss following the path of an artery out of the putamen was observed in 15 cases, and in 8 of these cases, the loss was greater than 10% of infusate. Backflow that exited the putamen was observed in 4 cases and led to large loss of infusate (80% in 1 case) into the corona radiata. Loss into the vacated catheter tract amounted only to a few microliters.

CONCLUSIONS

Our analysis demonstrates that after controlling for targeting, catheter type, infusion rate and infusate, the main issues during surgical planning are the identification of appropriate infusate volume that matches the target area, as well as mapping the regional vasculature as it may become a pathway for infusate loss. Most importantly, these results underscore the significance of presurgical planning for catheter placement and infusion, and the value of imaging guidance to ensure targeting accuracy.

Clinical outcome of deep brain stimulation for Parkinson's disease

Deep brain stimulation is one of the most effective treatments of Parkinson's disease (PD). This report summarizes the state of the art as at January 2013. Stimulation of the subthalamic nucleus is the most commonly used approach. It improves the core motor symptoms better than medication in patients with advanced disease. It also improves the majority of nonmotor symptoms, such as mood, impulse control disorders, sleep, and some autonomic dysfunctions. Quality of life (QoL) is improved significantly more than with medication. Long-term data show that the treatment is effective for up to 10 years, but the late appearance of l-dopa-resistant symptoms is seemingly not influenced. Internal globus pallidus (GPi) stimulation is less well studied but seems to have similar short-term efficacy. Importantly l-dopa use cannot be reduced with GPi DBS, which is a major disadvantage for patients suffering from medication side-effects, although gait may be influenced more positively. Although short-term QoL improvement seems to be similar to that for subthalamic nucleus (STN) DBS - gait and speech may be better improved - long-term data are rare for GPi DBS. Thalamic stimulation in the ventral intermediate nucleus (VIM) is applied only in tremor-dominant elderly patients. The treatment improves the dopa-sensitive symptoms and effectively reduces fluctuations leading to an overall QoL improvement. Although most of the controlled studies have been on advanced PD, the recently published EARLYSTIM study suggests that even patients with a very short duration of their fluctuations and dyskinesia are doing significantly better with neurostimulation in terms of QoL and all major motor outcome parameters.

Etiologies of intracerebral hematomas

Intracerebral hemorrhage (ICH) remains a life-threatening disease that carries significant morbidity and mortality despite recent diagnostic and management advances. Various conditions are associated with increased risk of intracerebral hemorrhage. Understanding the etiology of these conditions and their pathophysiological contribution to ICH will likely lead to better therapeutic and preventative measures and improve the morbidity and mortality associated with intracerebral hemorrhage. We will review the current literature regarding important etiologies/risk factors of intracerebral hemorrhage.

A theoretical framework for early human studies: uncertainty, intervention ensembles, and boundaries

Clinical development of novel therapeutics begins with a coordinated sequence of early phase clinical trials. Such early human studies confront a series of methodological and ethical challenges. In what follows, I propose a theoretical framework for early human studies aimed at informing the negotiation of these challenges. At the outset of clinical development, researchers confront a virtually undifferentiated landscape of uncertainty with respect to three variables: outcomes, their probability of occurrence, and operation dimensions needed to effectuate favorable outcomes. Early human trials transform this uncertain landscape into one where there are grounds for belief about risk and benefit for various combined operation dimensions. To accomplish this, studies set out with two aims. First, they identify a set of operation dimensions that, when combined as a package (intervention ensemble), elicits a reasonable probability of a target outcome. Second, they define the boundaries of dimension values within an intervention ensemble. This latter aim entails exposing at least some volunteers in early studies to treatments that are inactive or excessive. I provide examples that illustrate the way early human studies discover and delimit intervention ensembles, and close by offering some implications of this framework for ethics, methodology, and efficiency in clinical development of new interventions.

Sham neurosurgical procedures in clinical trials for neurodegenerative diseases: scientific and ethical considerations

There have been several recent scientific advances in gene-based and cell-based therapies that might translate into novel therapeutic approaches for neurodegenerative disorders. Such therapies might need to be directly delivered into the CNS, and complex scientific and ethical assessment will be needed to determine whether a sham neurosurgical arm should be included in clinical trials assessing these agents. We have developed a framework of points for investigators to consider when designing trials that involve direct delivery of a therapeutic agent to the CNS. The inclusion of a sham neurosurgical arm will be guided in part by the objectives of the clinical study (preliminary safety, optimisation, and feasibility vs preliminary efficacy vs confirmatory efficacy) and the need to minimise bias and confounds. Throughout the clinical development process, the perspectives of researchers, ethicists, and patients must be considered, and risks should be minimised whenever possible in a manner that is consistent with good trial design.

Deep brain stimulation for the treatment of Parkinson's disease: efficacy and safety

Deep brain stimulation (DBS) surgery has become increasingly utilized in the treatment of advanced Parkinson's disease. Over the past decade, a number of studies have demonstrated that DBS is superior to best medical management in appropriately selected patients. The primary targets for DBS in Parkinson's disease include the subthalamic nucleus and the internal segment of the globus pallidus, both of which improve the cardinal motor features in Parkinson's disease. Recent randomized studies have revealed that both targets are similarly effective in treating the motor symptoms of Parkinson's disease, but emerging evidence suggests that the globus pallidus may be the preferred target in many patients, based on differences in nonmotor outcomes. Here, we review appropriate patient selection, and the efficacy and safety of DBS therapy in Parkinson's disease. Best outcomes are achieved if the problems of the individual patient are considered when evaluating surgical candidates and considering whether the subthalamic nucleus or the globus pallidus internus should be targeted.