Thirty days complication rate following surgery performed for deep‐brain‐stimulation

Advanced age is not a barrier to chronic intracortical single-unit recording in rat cortex

Introduction

Available evidence suggests that as we age, our brain and immune system undergo changes that increase our susceptibility to injury, inflammation, and neurodegeneration. Since a significant portion of the potential patients treated with a microelectrode-based implant may be older, it is important to understand the recording performance of such devices in an aged population.

Methods

We studied the chronic recording performance and the foreign body response (FBR) to a clinically used microelectrode array implanted in the cortex of 18-month-old Sprague Dawley rats.

Results and discussion

To the best of our knowledge, this is the first preclinical study of its type in the older mammalian brain. Here, we show that single-unit recording performance was initially robust then gradually declined over a 12-week period, similar to what has been previously reported using younger adult rats and in clinical trials. In addition, we show that FBR biomarker distribution was similar to what has been previously described for younger adult rats implanted with multi-shank recording arrays in the motor cortex. Using a quantitative immunohistochemcal approach, we observed that the extent of astrogliosis and tissue loss near the recording zone was inversely related to recording performance. A comparison of recording performance with a younger cohort supports the notion that aging, in and of itself, is not a limiting factor for the clinical use of penetrating microelectrode recording arrays for the treatment of certain CNS disorders.

Transcranial focused ultrasound stimulation in the infralimbic cortex facilitates extinction of conditioned fear in rats

Transcranial focused ultrasound (tFUS) neuromodulation emerges as a promising non-invasive approach for improving neurological conditions. Extinction of conditioned fear has served as a prime model for exposure-based therapies for anxiety disorders. We investigated whether tFUS stimulation to a critical brain area, the infralimbic subdivision of the prefrontal cortex (IL), could facilitate fear extinction using rats. In a series of experiments, tFUS was delivered to the IL of a freely-moving rat and compared to sham stimulation (tFUS vs. SHAM). Initially, Fos expression in the IL was measured shortly after the stimulation. The results show that Fos expression was significantly increased in the IL but not in the neighboring regions compared to SHAM. Subsequently, two groups of rats were subjected to fear conditioning, extinction, and retention while receiving stimulation during the extinction. Rats in the tFUS group froze significantly less than SHAM during both extinction and retention tests. Importantly, the reduced freezing in the tFUS group was not attributable to non-specific effect such as auditory noise, as both groups demonstrated a similar level of locomotive activity in an open field regardless of the stimulation condition. Finally, we replicated the procedure with a shortened conditioning-to-extinction interval (15 min) to induce immediate extinction deficit. The tFUS group showed a facilitated reduction in freezing during the extinction, which persisted in the subsequent retention session compared to SHAM. In summary, the current findings suggest that tFUS stimulation in the IL facilitates fear extinction, offering a potential therapeutic regimen for fear-related psychiatric disorders.

Deep Brain Stimulation for Focal or Segmental Craniocervical Dystonia in Patients Who Have Failed Botulinum Neurotoxin Therapy-A Narrative Review of the Literature

(1) Background: The first-line treatment for patients with focal or segmental dystonia with a craniocervical distribution is still the intramuscular injection of botulinum neurotoxin (BoNT). However, some patients experience primary or secondary treatment failure from this potential immunogenic therapy. Deep brain stimulation (DBS) may then be used as a backup strategy in this situation. (2) Methods: Here, we reviewed the current study literature to answer a specific question regarding the efficacy and safety of the use of DBS, particularly for cervical dystonia (CD) and Meige syndrome (MS) in patients with documented treatment failure under BoNT. (3) Results: There are only two studies with the highest level of evidence in this area. Despite this clear limitation, in the context of the narrowly defined research question of this paper, it is possible to report 161 patients with CD or MS who were included in studies that were able to show a statistically significant reduction in dystonic symptoms using DBS. Safety and tolerability data appeared adequate. However, much of the information is based on retrospective observations. (4) Conclusions: The evidence base in this area is in need of further scientific investigation. Most importantly, more randomized, controlled and double-blind trials are needed, possibly including a head-to-head comparison of DBS and BoNT.

Outpatient Deep Brain Stimulation Surgery Is a Safe Alternative to Inpatient Admission

BACKGROUND

Deep brain stimulation (DBS) is usually performed as an inpatient procedure. The COVID-19 pandemic effected a practice change at our institution with outpatient DBS performed because of limited inpatient and surgical resources. Although this alleviated use of hospital resources, the comparative safety of outpatient DBS surgery is unclear.

OBJECTIVE

To compare the safety and incidence of early postoperative complications in patients undergoing DBS procedures in the outpatient vs inpatient setting.

METHODS

We retrospectively reviewed all outpatient and inpatient DBS procedures performed by a single surgeon between January 2018 and November 2022. The main outcome measures used for comparison between the 2 groups were total complications, length of stay, rate of postoperative infection, postoperative hemorrhage rate, 30-day emergency department (ED) visits and readmissions, and IV antihypertensive requirement.

RESULTS

A total of 44 outpatient DBS surgeries were compared with 70 inpatient DBS surgeries. The outpatient DBS cohort had a shorter mean postoperative stay (4.19 vs 39.59 hours, P = .0015), lower total complication rate (2.3% vs 12.8%, P = .1457), and lower wound infection rate (0% vs 2.9%, P = .52) compared with the inpatient cohort, but the difference in complications was not statistically significant. In the 30-day follow-up period, ED visits were similar between the cohorts (6.8% vs 7.1%, P = .735), but no outpatient DBS patient required readmission, whereas all inpatient DBS patients visiting the ED were readmitted (P = .155).

CONCLUSION

Our study demonstrates that DBS can be safely performed on an outpatient basis with same-day hospital discharge and close continuous monitoring.

Deep Brain Stimulation for Parkinson's Disease

There is a long history of surgical treatment for Parkinson's disease (PD). Currently, deep brain stimulation (DBS) has been performed as promising treatment option for medically refractory PD. DBS is an adjustable and reversible treatment using implanted medical devices to deliver electrical stimulation to precisely targeted areas of the brain. DBS modulates neurological function of the target region. The most common target for PD is the subthalamic nucleus (STN). DBS is particularly indicated for patients suffering from motor complications of dopaminergic medication such as fluctuations and dyskinesia. Although there is currently no curative treatment for PD, a combination of medical treatment and DBS provide long-term relief of motor symptoms. In this review, I introduce history, mechanism, indication, clinical outcome, complication, long term outcome, timing of surgery, surgical procedure, and current new technology concerning DBS for PD.

Classification of Kinematic and Electromyographic Signals Associated with Pathological Tremor Using Machine and Deep Learning

Peripheral Electrical Stimulation (PES) of afferent pathways has received increased interest as a solution to reduce pathological tremors with minimal side effects. Closed-loop PES systems might present some advantages in reducing tremors, but further developments are required in order to reliably detect pathological tremors to accurately enable the stimulation only if a tremor is present. This study explores different machine learning (K-Nearest Neighbors, Random Forest and Support Vector Machines) and deep learning (Long Short-Term Memory neural networks) models in order to provide a binary (Tremor; No Tremor) classification of kinematic (angle displacement) and electromyography (EMG) signals recorded from patients diagnosed with essential tremors and healthy subjects. Three types of signal sequences without any feature extraction were used as inputs for the classifiers: kinematics (wrist flexion-extension angle), raw EMG and EMG envelopes from wrist flexor and extensor muscles. All the models showed high classification scores (Tremor vs. No Tremor) for the different input data modalities, ranging from 0.8 to 0.99 for the f₁ score. The LSTM models achieved 0.98 f₁ scores for the classification of raw EMG signals, showing high potential to detect tremors without any processed features or preliminary information. These models may be explored in real-time closed-loop PES strategies to detect tremors and enable stimulation with minimal signal processing steps.

Treating Chronic Pain with Deep Brain Stimulation

PURPOSE OF REVIEW

Deep brain stimulation (DBS) for chronic pain has been controversial. Despite the discouraging outcomes from multicenter clinical trial in the twentieth century, there is sustained interest in optimizing its use to improve patient outcomes. Here we provide a concise overview of DBS for chronic pain as a reference for clinicians.

RECENT FINDINGS

Recently published data lends tentative support for DBS as a means of treating chronic pain. Still, high level-of-evidence data remain elusive. There are a handful of ongoing and prospective clinical trials exploring DBS for pain in the context of closed-loop neuromodulation, invasive electroencephalography monitoring, stimulation parameters, and novel intracranial targets. DBS is a potentially viable method of treating chronic pain. Procedure success is dependent on a number of factors including proper patient and intracranial target selection. Outcomes for ongoing and future clinical trials will help clinicians refine DBS use for this clinical indication.

Development of a wireless ultrasonic brain stimulation system for concurrent bilateral neuromodulation in freely moving rodents

Bilateral brain stimulation is an important modality used to investigate brain circuits and treat neurological conditions. Recently, low-intensity pulsed ultrasound (LIPUS) received significant attention as a novel non-invasive neurostimulation technique with high spatial specificity. Despite the growing interest, the typical ultrasound brain stimulation study, especially for small animals, is limited to a single target of sonication. The constraint is associated with the complexity and the cost of the hardware system required to achieve multi-regional sonication. This work presented the development of a low-cost LIPUS system with a pair of single-element ultrasound transducers to address the above problem. The system was built with a multicore processor with an RF amplifier circuit. In addition, LIPUS device was incorporated with a wireless module (bluetooth low energy) and powered by a single 3.7 V battery. As a result, we achieved an ultrasound transmission with a central frequency of 380 kHz and a peak-to-peak pressure of 480 kPa from each ultrasound transducer. The developed system was further applied to anesthetized rats to investigate the difference between uni- and bilateral stimulation. A significant difference in cortical power density extracted from electroencephalogram signals was observed between uni- and bilateral LIPUS stimulation. The developed device provides an affordable solution to investigate the effects of LIPUS on functional interhemispheric connection.

Optimized Deep Brain Stimulation Surgery to Avoid Vascular Damage: A Single-Center Retrospective Analysis of Path Planning for Various Deep Targets by MRI Image Fusion

Co-registration of stereotactic and preoperative magnetic resonance imaging (MRI) images can serve as an alternative for trajectory planning. However, the role of this strategy has not yet been proven by any control studies, and the trajectories of commonly used targets have not been systematically studied. The purpose of this study was to analyze the trajectories for various targets, and to assess the role of trajectories realized on fused images in preventing intracranial hemorrhage (ICH). Data from 1019 patients who underwent electrode placement for deep brain stimulation were acquired. Electrode trajectories were not planned for 396 patients, whereas trajectories were planned for 623 patients. Preoperative various MRI sequences and frame-placed MRI images were fused for trajectory planning. The patients’ clinical characteristics, the stereotactic systems, intracranial hemorrhage cases, and trajectory angles were recorded and analyzed. No statistically significant differences in the proportions of male patients, patients receiving local anesthesia, and diseases or target distributions (p > 0.05) were found between the trajectory planning group and the non-trajectory planning group, but statistically significant differences were observed in the numbers of both patients and leads associated with symptomatic ICH (p < 0.05). Regarding the ring and arc angle values, statistically significant differences were found among various target groups (p < 0.05). The anatomic structures through which leads passed were found to be diverse. Trajectory planning based on MRI fusion is a safe technique for lead placement. The electrode for each given target has its own relatively constant trajectory.

Preoperative evaluation of coagulation status in neuromodulation patients

OBJECTIVE

The incidence of hemorrhage in patients who undergo deep brain stimulation (DBS) and spinal cord stimulation (SCS) is between 0.5% and 2.5%. Coagulation status is one of the factors that can predispose patients to the development of these complications. As a routine part of preoperative assessment, the authors obtain prothrombin time (PT), partial thromboplastin time (PTT), and platelet count. However, insurers often cover only PT/PTT laboratory tests if the patient is receiving warfarin/heparin. The authors aimed to examine their experience with abnormal coagulation parameters in patients who underwent neuromodulation.

METHODS

Patients who underwent neuromodulation (SCS, DBS, or intrathecal pump implantation) over a 9-year period and had preoperative laboratory values available were included. The authors determined abnormal values on the basis of a clinical protocol utilized at their practice, which combined the normal ranges of the laboratory tests and clinical relevance. This protocol had cutoff values of 12 seconds and 39 seconds for PT and PTT, respectively, and < 120,000 platelets/μl. The authors identified risk factors for these abnormalities and described interventions.

RESULTS

Of the 1767 patients who met the inclusion criteria, 136 had abnormal preoperative laboratory values. Five of these 136 patients had values that were misclassified as abnormal because they were within the normal ranges at the outside facility where they were tested. Fifty-one patients had laboratory values outside the ranges of our protocol, but the surgeons reviewed and approved these patients without further intervention. Of the remaining 80 patients, 8 had known coagulopathies and 24 were receiving warfarin/heparin. The remaining 48 patients were receiving other anticoagulant/antiplatelet medications. These included apixaban/rivaroxaban/dabigatran anticoagulants (n = 22; mean ± SD PT 13.7 ± 2.5 seconds) and aspirin/clopidogrel/other antiplatelet medications (n = 26; mean ± SD PT 14.4 ± 5.8 seconds). Eight new coagulopathies were identified and further investigated with hematological analysis.

CONCLUSIONS

New anticoagulants and antiplatelet medications are not monitored with PT/PTT, but they affect coagulation status and laboratory values. Although platelet function tests aid in a subset of medications, it is more difficult to assess the coagulation status of patients receiving novel anticoagulants. PT/PTT may provide value preoperatively.

Complications After Deep Brain Stimulation: A 21-Year Experience in 426 Patients

Background

Deep brain stimulation is an established treatment for movement disorders such as Parkinson’s disease, essential tremor, and dystonia. However, various complications that occur after deep brain stimulation are a major concern for patients and neurosurgeons.

Objective

This study aimed to analyze various complications that occur after deep brain stimulation.

Methods

We reviewed the medical records of patients with a movement disorder who underwent bilateral deep brain stimulation between 2000 and 2020. Among them, patients requiring revision surgery were analyzed.

Results

A total of 426 patients underwent bilateral deep brain stimulation for a movement disorder. The primary disease was Parkinson’s disease in 315 patients, followed by dystonia in 71 patients and essential tremor in 40 patients. Twenty-six (6.1%) patients had complications requiring revision surgery; the most common complication was infection (12 patients, 2.8%).

Conclusion

Various complications may occur after deep brain stimulation, and patient prognosis should be improved by reducing complications.

Deep brain stimulation in patients on chronic antiplatelet or anticoagulation treatment

BACKGROUND

In the aging society, many patients with movement disorders, pain syndromes, or psychiatric disorders who are candidates for deep brain stimulation (DBS) surgery suffer also from cardiovascular co-morbidities that require chronic antiplatelet or anticoagulation treatment. Because of a presumed increased risk of intracranial hemorrhage during or after surgery and limited knowledge about perioperative management, chronic antiplatelet or anticoagulation treatment often has been considered a relative contraindication for DBS. Here, we evaluate whether or not there is an increased risk for intracranial hemorrhage or thromboembolic complications in patients on chronic treatment (paused for surgery or bridged with subcutaneous heparin) as compared to those without.

METHODS

Out of a series of 465 patients undergoing functional stereotactic neurosurgery, 34 patients were identified who were on chronic treatment before and after receiving DBS. In patients with antiplatelet treatment, medication was stopped in the perioperative period. In patients with vitamin K antagonists or novel oral anticoagulants (NOACs), heparin was used for bridging. All patients had postoperative stereotactic CT scans, and were followed up for 1 year after surgery.

RESULTS

In patients on chronic antiplatelet or anticoagulation treatment, intracranial hemorrhage occurred in 2/34 (5.9%) DBS surgeries, whereas the rate of intracranial hemorrhage was 15/431 (3.5%) in those without, which was statistically not significant. Implantable pulse generator pocket hematomas were seen in 2/34 (5.9%) surgeries in patients on chronic treatment and in 4/426 (0.9%) without. There were only 2 instances of thromboembolic complications which both occurred in patients without chronic treatment. There were no hemorrhagic complications during follow-up for 1 year.

CONCLUSIONS

DBS surgery in patients on chronic antiplatelet or anticoagulation treatment is feasible. Also, there was no increased risk of hemorrhage in the first year of follow-up after DBS surgery. Appropriate patient selection and standardized perioperative management are necessary to reduce the risk of intracranial hemorrhage and thromboembolic complications.

Subthalamic and pallidal deep brain stimulation for Parkinson's disease-meta-analysis of outcomes

Although deep brain stimulation (DBS) of the globus pallidus internus (GPi) and the subthalamic nucleus (STN) has become an established treatment for Parkinson’s disease (PD), a recent meta-analysis of outcomes is lacking. To address this gap, we performed a meta-analysis of bilateral STN- and GPi-DBS studies published from 1990-08/2019. Studies with ≥10 subjects reporting Unified Parkinson’s Disease Rating Scale (UPDRS) III motor scores at baseline and 6–12 months follow-up were included. Several outcome variables were analyzed and adverse events (AE) were summarized. 39 STN studies (2035 subjects) and 5 GPi studies (292 subjects) were eligible. UPDRS-II score after surgery in the stimulation-ON/medication-OFF state compared to preoperative medication-OFF state improved by 47% with STN-DBS and 18.5% with GPi-DBS. UPDRS-III score improved by 50.5% with STN-DBS and 29.8% with GPi-DBS. STN-DBS improved dyskinesia by 64%, daily OFF time by 69.1%, and quality of life measured by PDQ-39 by 22.2%, while Levodopa Equivalent Daily Dose (LEDD) was reduced by 50.0%. For GPi-DBS information regarding dyskinesia, OFF time, PDQ-39 and LEDD was insufficient for further analysis. Correlation analysis showed that preoperative L-dopa responsiveness was highly predictive of the STN-DBS motor outcome across all studies. Most common surgery-related AE were infection (5.1%) and intracranial hemorrhage (3.1%). Despite a series of technological advances, outcomes of modern surgery are still comparable with those of the early days of DBS. Recent changes in target selection with a preference of GPi in elderly patients with cognitive deficits and more psychiatric comorbidities require more published data for validation.

Deep Brain Stimulation for Tremor and Dystonia

Deep brain stimulation (DBS) is the most commonly used surgical treatment for drug-refractory movement disorders such as tremor and dystonia. Appropriate patient selection along with target selection is important to ensure optimal outcome without complications. This review summarizes the recent literature regarding the mechanism of action, indications, outcome, and complications of DBS in tremor and dystonia. A comparison with other modalities of surgical interventions is discussed along with a note of the recent advances in technology. Future research needs to be directed to understand the underlying etiopathogenesis of the disease and the way in which DBS modulates the intracranial abnormal networks.

Correlates of deep brain stimulation consensus conference decision to treat primary dystonia

BACKGROUND

Deep brain stimulation (DBS) is an effective treatment for motor disturbance in people with primary dystonia (PWD). Numerous factors are considered by an interdisciplinary consensus conference before deciding candidacy for DBS surgery (e.g., demographic, medical, cognitive, and behavioral factors). However, little is known about which of these factors are associated with PWD DBS surgery consensus conference decisions.

OBJECTIVE

Our goal was to examine whether pre-operative demographic, medical, and cognitive/behavioral variables are associated DBS consensus conference decisions in patients with dystonia.

METHODS

Thirty-two PWD completed comprehensive presurgery workup included neurological and neuropsychological exams, and neuroimaging in consideration for DBS surgery. An interdisciplinary conference committee either recommended or did not recommend DBS surgery based upon these data. Demographic and medical data (e.g., dystonia disease characteristics, medical comorbidities, medications) were also collected. We also examined impact from cardiovascular disease factors, using a Revised Cardiac Risk Index. PWD were grouped based on DBS conference decision (eligible: n = 21, ineligible: n = 11) and compared across demographic, medical, and cognitive/behavioral variables.

RESULTS

Across clinical variables, PWD who were deemed ineligible for DBS surgery had a higher Revised Cardiac Risk Index. PWD who were classified as ineligible displayed lower global cognitive functioning, working memory, phonemic fluency, memory retrieval, and cognitive flexibility.

CONCLUSIONS

Consensus decision making regarding DBS surgery eligibility involves a multifactorial process. We found that deficits in executive functioning were associated with the DBS consensus committee decision. We also observed elevated cardiac risk among these individuals, likely reflecting the relation between vascular health and cognition. Implications, and clinical and scientific applications of these findings are discussed.

Ventralis oralis anterior (Voa) deep brain stimulation plus Gamma Knife thalamotomy in an elderly patient with essential tremor: A case report

RATIONALE

Deep brain stimulation (DBS) of the ventralis intermedius nucleus (Vim) provides a safe and effective therapy for medically refractory essential tremor (ET). However, DBS may be risky in elderly patients and those with ischemic brain lesions. Gamma Knife radiosurgery (GKS) is a minimally invasive procedure, but bilateral thalamotomy is dangerous.

PATIENT CONCERNS

We report a case of ventralis oralis anterior nucleus (Voa) DBS for dominant hand tremor plus Voa GKS for nondominant hand tremor in a very elderly patient with medically intractable ET.

DIAGNOSIS

An 83-year-old right-handed woman visited our hospital with a medically intractable ET. Because of the ischemic lesion in the right basal ganglia, we decided to perform left unilateral DBS instead of bilateral DBS.

INTERVENTION

We chose Voa as the target for DBS because, clinically, her tremor was mainly confined to her hands, and Voa had better intraoperative microelectrode recording results than Vim.

OUTCOMES

After 2 years, her right-hand tremor remained in an improved state, but she still had severe tremor in her left hand. Therefore, we performed GKS targeting the right Voa. One year after surgery, the patient's hand tremor successfully improved without any complications.

LESSONS

Salvage Voa GKS after unilateral Voa DBS is a valuable option for very elderly patients and patients with ischemic brain lesions. We suggest that Voa GKS thalamotomy is as useful and safe a surgical technique as Vim GKS for dystonic hand tremor. To the best of our knowledge, this is the first case report using salvage Voa as the only target for ET.

Arching deep brain stimulation in dystonia types

Although medical treatment including botulinum toxic injection is the first-line treatment for dystonia, response is insufficient in many patients. In these patients, deep brain stimulation (DBS) can provide significant clinical improvement. Mounting evidence indicates that DBS is an effective and safe treatment for dystonia, especially for idiopathic and inherited isolated generalized/segmental dystonia, including DYT-TOR1A. Other inherited dystonia and acquired dystonia also respond to DBS to varying degrees. For Meige syndrome (craniofacial dystonia), other focal dystonia, and some rare inherited dystonia, further evidences are still needed to evaluate the role of DBS. Because short disease duration at DBS surgery and absence of fixed musculoskeletal deformity are associated with better outcome, DBS should be considered as early as possible when indicated after careful evaluation including genetic work-up. This review will focus on the factors to be considered in DBS for patients with dystonia and the outcome of DBS in the different types of dystonia.

A qualitative study of key stakeholders' perceived risks and benefits of psychiatric electroceutical interventions

Amid a renewed interest in alternatives to psychotherapy and medication to treat depression, there is limited data as to how different stakeholders perceive of the risks and benefits of psychiatric electroceutical interventions (PEIs), including electroconvulsive therapy (ECT) and deep brain stimulation (DBS). To address this gap, we conducted 48 semi-structured interviews, including 16 psychiatrists, 16 persons diagnosed with depression, and 16 members of the general public. To provide a basis of comparison, we asked participants to also compare each modality to front-line therapies for depression and to neurosurgical procedures used for non-psychiatric conditions. Across all stakeholder groups, perceived memory loss was the most frequently mentioned potential risk with ECT. The most discussed benefits across all stakeholder groups were efficacy and quick response. Psychiatrists most often referenced effectiveness when discussing ECT, while patients and the public did so when discussing DBS. Taken as a whole, these data highlight stakeholders' contrasting perspectives on the risks and benefits of electroceuticals.

Incidence and risk factors for seizures associated with deep brain stimulation surgery

OBJECTIVE

The objective of this study was to determine the incidence of seizures following deep brain stimulation (DBS) electrode implantation and to evaluate factors associated with postoperative seizures.

METHODS

The authors performed a single-center retrospective case-control study. The outcome of interest was seizure associated with DBS implantation. Univariate analyses were performed using the Student t-test for parametric continuous outcomes. The authors used the Kruskal-Wallis test or Wilcoxon rank-sum test for nonparametric continuous outcomes, chi-square statistics for categorical outcomes, and multivariate logistic regression for binomial variables.

RESULTS

A total of 814 DBS electrode implantations were performed in 645 patients (478 [58.7%] in men and 520 [63.9%] in patients with Parkinson's disease). In total, 22 (3.4%) patients who had undergone 23 (2.8%) placements experienced seizure. Of the 23 DBS implantation-related seizures, 21 were new-onset seizures (3.3% of 645 patients) and 2 were recurrence or worsening of a prior seizure disorder. Among the 23 cases with postimplantation-related seizure, epilepsy developed in 4 (17.4%) postoperatively; the risk of DBS-associated epilepsy was 0.50% per DBS electrode placement and 0.63% per patient. Nine (39.1%) implantation-related seizures had associated postoperative radiographic abnormalities. Multivariate analyses suggested that age at surgery conferred a modest increased risk for postoperative seizures (OR 1.06, 95% CI 1.02-1.10). Sex, primary diagnosis, electrode location and sidedness, and the number of trajectories were not significantly associated with seizures after DBS surgery.

CONCLUSIONS

Seizures associated with DBS electrode placement are uncommon, typically occur early within the postoperative period, and seldom lead to epilepsy. This study suggests that patient characteristics, such as age, may play a greater role than perioperative variables in determining seizure risk. Multiinstitutional studies may help better define and mitigate the risk of seizures after DBS surgery.

Outcomes and Adverse Effects of Deep Brain Stimulation on the Ventral Intermediate Nucleus in Patients with Essential Tremor

Objective

This study was aimed at identifying the potential outcome predictors, comparing the efficacy in patients with different tremor characteristics, and summarizing the adverse effect rates (AERs) of deep brain stimulation on the ventral intermediate nucleus (VIM-DBS) for essential tremor (ET).

Methods

An extensive search of articles published to date in 2019 was conducted, and two main aspects were analyzed. Improvement was calculated as a percentage of change in any objective tremor rating scale (TRS) and analyzed by subgroup analyses of patients' tremor characteristics, laterality, and stimulation parameters. Furthermore, the AERs were analyzed as follows: the adverse effects (AEs) were classified as stimulation-related, surgical-related, or device-related effects. A simple regression analysis was used to identify the potential prognostic factors, and a two-sample mean-comparison test was used to verify the statistical significance of the subgroup analyses.

Results

Forty-six articles involving 1714 patients were included in the meta-analysis. The pooled improvement in any objective TRS score was 61.3% (95% CI: 0.564-0.660) at the mean follow-up visit (20.0 ± 17.3 months). The midline and extremity symptoms showed consistent improvement (P = 0.440), and the results of the comparison of postural and kinetic tremor were the same (P = 0.219). In addition, the improvement in rest tremor was similar to that in action tremor (OR = 2.759, P = 0.120). In the simple regression analysis, the preoperative Fahn-Tolosa-Marin Tremor Rating Scale (FTM-TRS) scores and follow-up time were negatively correlated with the percentage change in any objective TRS score (P < 0.05). The most common adverse event was dysarthria (10.5%), which is a stimulation-related AE (23.6%), while the rates of the surgical-related and device-related AEs were 6.4% and 11.5%, respectively.

Conclusion

VIM-DBS is an efficient and safe surgical method in ET, and the efficacy was not affected by the body distribution of tremor, age at surgery, and disease duration. Lower preoperative FTM-TRS scores likely indicate greater improvement, and the effect of VIM-DBS declines over time.

Evaluation of Novel Stereotactic Cannula for Stem Cell Transplantation against Central Nervous System Disease

Cell therapy for central nervous system (CNS) disorders is beginning to prove its safety and efficiency. Intraparenchymal transplantation can be an option for cell delivery; however, one concern regarding this method is that the transplantation cannula may cause additional brain injuries. These include vessel damage, which results in brain hemorrhage, and clogging of the cannula by brain debris and/or cell clusters, which requires replacement of the cannula or forced injection causing jet flow of the cell suspension. We compared cannulas for cell delivery used in clinical trials, the Pittsburg and Mizuho cannulas, to a newly designed one, MK01, to assess their usability. MK01 has a spherical-shaped tip with a fan-like open orifice on the side of the cannula, which prevents vessel damage, clogging of brain debris, and jet flow phenomenon. We compared the extent of rat cervical and abdominal arterial damage with the cannula, the amount of debris in the cannula, the force needed to cause jet flow, and cell viability. While the viability of cells passed through the cannulas was almost the same among cannulas (approximately 95%), the Pittsburg cannula caused cervical arterial injury and subsequent hemorrhage, as it required a significantly smaller force to penetrate the arterial wall. Moreover, the Pittsburg cannula, but not the Mizuho and MK01 cannulas, showed high frequency of brain debris in the needle tip (approximately 80%) after brain puncture. While jet flow of the injection liquid was observed even when using smaller forces in the Pittsburg and Mizuho cannulas, MK01 constantly showed low jet flow occurrence. Thus, MK01 seems to be safer than the previously reported cannulas, although further investigation is necessary to validate its safety for clinical use.

Comparison of elderly and young patient populations treated with deep brain stimulation for Parkinson's disease: long-term outcomes with up to 7 years of follow-up

OBJECTIVE

Deep brain stimulation (DBS) is the procedure of choice for Parkinson's disease (PD). It has been used in PD patients younger than 70 years because of better perceived intra- and postoperative outcomes than in patients 70 years or older. However, previous studies with limited follow-up have demonstrated benefits associated with the treatment of elderly patients. This study aims to evaluate the long-term outcomes in elderly PD patients treated with DBS in comparison with a younger population.

METHODS

PD patients treated with DBS at the authors' institution from 2008 to 2014 were divided into 2 groups: 1) elderly patients, defined as having an age at surgery ≥ 70 years, and 2) young patients, defined as those < 70 years at surgery. Functional and medical treatment outcomes were evaluated using the Unified Parkinson's Disease Rating Scale part III (UPDRS III), levodopa-equivalent daily dose (LEDD), number of daily doses, and number of anti-PD medications. Study outcomes were compared using univariate analyses, 1-sample paired t-tests, and 2-sample t-tests.

RESULTS

A total of 151 patients were studied, of whom 24.5% were ≥ 70 years. The most common preoperative Hoehn and Yahr stages for both groups were 2 and 3. On average, elderly patients had more comorbidities at the time of surgery than their younger counterparts (1 vs 0, p = 0.0001) as well as a higher average LEDD (891 mg vs 665 mg, p = 0.008). Both groups experienced significant decreases in LEDD following surgery (elderly 331.38 mg, p = 0.0001; and young 108.6 mg, p = 0.0439), with a more significant decrease seen in elderly patients (young 108.6 mg vs elderly 331.38 mg, p = 0.0153). Elderly patients also experienced more significant reductions in daily doses (young 0.65 vs elderly 3.567, p = 0.0344). Both groups experienced significant improvements in motor function determined by reductions in UPDRS III scores (elderly 16.29 vs young 12.85, p < 0.0001); however, reductions in motor score between groups were not significant. Improvement in motor function was present for a mean follow-up of 3.383 years postsurgery for the young group and 3.51 years for the elderly group. The average follow-up was 40.6 months in the young group and 42.2 months in the elderly group.

CONCLUSIONS

This study found long-term improvements in motor function and medication requirements in both elderly and young PD patients treated with DBS. These outcomes suggest that DBS can be successfully used in PD patients ≥ 70 years. Further studies will expand on these findings.

A meta-analysis of outcomes and complications of magnetic resonance-guided focused ultrasound in the treatment of essential tremor

OBJECTIVE Magnetic resonance-guided focused ultrasound (MRgFUS) is a novel technique that uses high-intensity focused ultrasound to achieve target ablation. Like a lens focusing the sun's rays, the ultrasound waves are focused to generate heat. This therapy combines the noninvasiveness of Gamma Knife thalamotomy and the real-time ablation of deep brain stimulation with acceptable complication rates. The aim of this study was to analyze the overall outcomes and complications of MRgFUS in the treatment of essential tremor (ET). METHODS A meta-analysis in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was made by searching PubMed, Cochrane library database, Web of Science, and Cumulative Index to Nursing and Allied Health Literature (CINAHL). Patients with the diagnosis of ET who were treated with MRgFUS were included in the study. The change in the Clinical Rating Scale for Tremor (CRST) score after treatment was analyzed. The improvement in disability was assessed with the Quality of Life in Essential Tremor Questionnaire (QUEST) score. The pooled data were analyzed by the DerSimonian-Laird random-effects model. Tests for bias and heterogeneity were performed. RESULTS Nine studies with 160 patients who had ET were included in the meta-analysis. The ventral intermediate nucleus was the target in 8 of the studies. The cerebellothalamic tract was targeted in 1 study. There was 1 randomized controlled trial, 6 studies were retrospective, and 2 were prospective. The mean number of sonications given in various studies ranged from 11 ± 3.2 to 22.5 ± 7.5 (mean ± SD). The maximum delivered energy ranged from 10,320 ± 4537 to 14,497 ± 6695 Joules. The mean of peak temperature reached ranged from 53°C ± 2.3°C to 62.0°C ± 2.5°C. On meta-analysis with the random-effects model, the pooled percentage improvements in the CRST Total, CRST Part A, CRST Part C, and QUEST scores were 62.2%, 62.4%, 69.1%, and 46.5%, respectively. Dizziness was the most common in-procedure complication, occurring in 45.5%, followed by nausea and vomiting in 26.85% (pooled percentage). At 3 months, ataxia was the most common complication, occurring in 32.8%, followed by paresthesias in 25.1% of the patients. At 12 months posttreatment, the ataxia had significantly recovered and paresthesias became the most common persisting complication, at 15.3%. CONCLUSIONS The MRgFUS therapy for ET significantly improves the CRST scores and improves the quality of life in patients with ET, with an acceptable complication rate. Therapy with MRgFUS is a promising frontier in functional neurosurgery.

Bioelectronic Medicine-Ethical Concerns

Bioelectronic medicine (BEM) offers exciting opportunities to treat diseases such as movement disorders and refractory inflammatory disease. The many variations of BEM allow for noninvasive aspects of treatment that might eliminate or reduce the need for pharmaceuticals; therefore, the term "electroceuticals" may be suitable. BEM has been effective for movement disorders and improvement of prosthetic devices. Based on this implication, there is an allowance to impact many focus areas that include but are not limited to autoimmune disease, sensory motor conditions, and neurological conditions. There are a wide array of ethical issues that relate to BEM, which include informed consent, research ethics, innovation, academic-industry relationships, intellectual property, and the conundrum that needs to be addressed when altering the brain such as the issues of autonomy and free beneficence and social justice. The major goal is to heighten awareness of ethical issues and facilitate a proactive ethical approach regarding BEM research.

Predicting extended hospital stay after deep brain stimulation surgery in Parkinson's patients

BACKGROUND

The goal of deep brain stimulation (DBS) is to achieve maximal benefit for the patient while minimizing the likelihood of adverse effects. Currently, no standardized criteria exist that predicts extended hospital stay in DBS patients, although careful patient selection is recognized as a very important step for successful DBS therapy.

OBJECTIVES AND METHODS

The objective of this study was to identify eight key factors that predicted extended post-operative hospital stay following DBS lead implantation, in an effort to better identify patients that would require minimal hospital stay, resulting in reduced cost and reduced exposure to hospital- related problems. Univariate logistic regression models were used to examine associations between each factor and patients' post-surgical outcomes.

RESULTS

Using data collected from 183 patients, we found that 53 patients required a hospital stay longer than two days within one month post-procedure. Those who were 70 years or older and those who had frequent falls were significantly more likely to require extended post-surgical care. Patients that scored three points or higher on our eight-factor assessment scale had a greater likelihood of experiencing an event that would require an extended hospital stay following DBS lead placement, regardless of what three factors were present.

CONCLUSIONS

Any PD patient who is 70 years or older, incurring frequent falls, or with more than three points on our scale, should be carefully screened and cautioned about likely prolonged recovery and extended post-operative hospital stay.

Pre-operative smoking history increases risk of infection in deep brain stimulation surgery

Although general risk of deep brain stimulation (DBS) therapy has been previously described, application of risk prediction at the individual patient level is still largely at the discretion of a treating physician or a multidisciplinary team. To explore associations between potentially modifiable patient characteristics and common adverse events following DBS surgery, we retrospectively reviewed consecutive adult patients who had undergone new DBS electrode placement surgeries at two high-volume tertiary referral centers between October 1997 and May 2018. Among 501 patients included in the analysis (mean age (SD), 64.6 (10.4) years), 165 (32.9%) were female, 67 (13.4%) had diabetes, 231 (46.1%) had hypertension, 25 (5.0%) were smokers, 27 (5.4%) developed an infection, 15 (3.0%) had intracranial or intraventricular hemorrhage, and 53 (10.6%) had an unplanned return to the operating room. Patients who developed a surgical site infection were more likely to report history of smoking before DBS surgery (16% vs 5%, p = 0.04). There was a trend for patients with hypertension to be at risk for intracranial hemorrhage (p = 0.11). In conclusion, this multicenter study demonstrated an association between preoperative smoking and increased risk of infection following new DBS implantation surgery. Counseling about this risk should be considered in preoperative evaluation of patients who are considering undergoing a DBS procedure.

Detection of bacterial DNA on neurostimulation systems in patients without overt infection

OBJECTIVE

Hardware-related infection remains a major problem in patients with neurostimulation systems. The role of bacterial colonization and the formation of biofilm on the surface of implanted devices remain unclear. Here, we analysed the incidence of bacterial DNA on the surface of implantable pulse generators (IPGs) using 16S rRNA gene sequencing in a consecutive series of patients who underwent routine IPG replacement without clinical signs of infection.

PATIENTS AND METHODS

We included 36 patients who underwent scheduled replacement surgery of 44 IPGs. The removed IPGs were processed and whole genomic DNA was extracted. The detection of bacterial DNA was carried out by Polymerase Chain Reaction (PCR) using universal bacterial primers targeting the 16S rRNA gene. The DNA strands were analysed by single-strand conformation polymorphism (SSCP) analysis.

RESULTS

Indications for chronic neurostimulation were Parkinson disease, tremor, dystonia, neuropathic pain and peripheral artery occlusion disease. Mean age of patients at the time of implantation was 48 ± 17.6 years. The mean interval between implantation and replacement of the IPG was 24.8 months. PCR/SSCP detected bacterial DNA of various species in 5/36 patients (13.9%) and in 5/44 pacemakers (11.4%), respectively. There was no evidence of clinical infection or wound healing impairment during follow-up time of 45.6 ± 19.6 months.

CONCLUSION

Bacterial DNA can be detected on the surface of IPGs of neurostimulation systems in patients without clinical signs of infection by using PCR techniques. It remains unclear, similar to other permanently implanted devices, which mechanisms and processes promote progression to the point of overt infection.

An update on best practice of deep brain stimulation in Parkinson's disease

During the last 30 years, deep brain stimulation (DBS) has evolved into the clinical standard of care as a highly effective treatment for advanced Parkinson’s disease. Careful patient selection, an individualized anatomical target localization and meticulous evaluation of stimulation parameters for chronic DBS are crucial requirements to achieve optimal results. Current hardware-related advances allow for a more focused, individualized stimulation and hence may help to achieve optimal clinical results. However, current advances also increase the degrees of freedom for DBS programming and therefore challenge the skills of healthcare providers. This review gives an overview of the clinical effects of DBS, the criteria for patient, target, and device selection, and finally, offers strategies for a structured programming approach.

Hemorrhagic complications seen on immediate intraprocedural stereotactic computed tomography imaging during deep brain stimulation implantation

BACKGROUND

We present our operative experience of patients with movement disorders who developed intracerebral hemorrhage (ICH), which was identified on intraprocedural stereotactic computed tomography (CT) imaging performed immediately after deep brain stimulation (DBS) lead placement and prior to the implantation of further components of the DBS hardware.

METHODS

Patients who underwent DBS lead implantation from January 2009 through December 2017 were included in the present study. Most of the surgeries were performed in a staged fashion. All patients were operated using identical surgical and intraprocedural imaging techniques, and no microelectrode recordings were done. Leksell Stereotactic G frame and neuronavigation software was utilized for all surgeries. Intraprocedural stereotactic CT was performed to confirm the precise position of the implanted DBS lead and to rule out any hemorrhagic complications.

RESULTS

Overall, 222 patients underwent 322 DBS lead implantations during 316 stereotactic procedures. Six patients exhibited early ICH recognized on intraprocedural stereotactic CT performed immediately after DBS lead placement; in addition, two patients developed delayed ICH due to large venous infarction. Four patients with ICH were asymptomatic. The ICH rate was 2.5% per electrode and 3.6% per patient; the permanent deficit rate was 1.2% per electrode and 1.8% per patient. The death rate due to ICH in our cohort was 0.6% per electrode and 0.9% per patient.

CONCLUSIONS

Intraprocedural stereotactic CT can not only visualize the implanted DBS lead in the stereotactic space but also rule out early ICH. Identified predisposing factors for development of ICH include patient's age, hypertension, and previous antiplatelet therapy. Careful planning of stereotactic trajectories plays a paramount role in reducing the rate of ICH in DBS surgery.

Neurologic Medical Device Overview for Pathologists

Thorough morphologic evaluations of medical devices placed in or near the nervous system depend on many factors. Pathologists interpreting a neurologic device study must be familiar with the regulatory framework affecting device development, biocompatibility and safety determinants impacting nervous tissue responses, and appropriate study design, including the use of appropriate animal models, group design, device localization, euthanasia time points, tissue examination, sampling and processing, histochemistry and immunohistochemistry, and reporting. This overview contextualizes these features of neurologic medical devices for pathologists engaged in device evaluations.

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.

Towards unambiguous reporting of complications related to deep brain stimulation surgery: A retrospective single-center analysis and systematic review of the literature

Background and objective

To determine rates of adverse events (AEs) related to deep brain stimulation (DBS) surgery or implanted devices from a large series from a single institution. Sound comparisons with the literature require the definition of unambiguous categories, since there is no consensus on the reporting of such AEs.

Patients and methods

123 consecutive patients (median age 63 yrs; female 45.5%) treated with DBS in the subthalamic nucleus (78 patients), ventrolateral thalamus (24), internal pallidum (20), and centre médian-parafascicular nucleus (1) were analyzed retrospectively. Both mean and median follow-up time was 4.7 years (578 patient-years). AEs were assessed according to three unambiguous categories: (i) hemorrhages including other intracranial complications because these might lead to neurological deficits or death, (ii) infections and similar AEs necessitating the explantation of hardware components as this results in the interruption of DBS therapy, and (iii) lead revisions for various reasons since this involves an additional intracranial procedure. For a systematic review of the literature AE rates were calculated based on primary data presented in 103 publications. Heterogeneity between studies was assessed with the I² statistic and analyzed further by a random effects meta-regression. Publication bias was analyzed with funnel plots.

Results

Surgery- or hardware-related AEs (23) affected 18 of 123 patients (14.6%) and resolved without permanent sequelae in all instances. In 2 patients (1.6%), small hemorrhages in the striatum were associated with transient neurological deficits. In 4 patients (3.3%; 0.7% per patient-year) impulse generators were removed due to infection. In 2 patients electrodes were revised (1.6%; 0.3% per patient-year). There was no lead migration or surgical revision because of lead misplacement. Age was not statistically significant different (p>0.05) between patients affected by AEs or not. AE rates did not decline over time and similar incidences were found among all patients (423) implanted with DBS systems at our institution until December 2016. A systematic literature review revealed that exact AE rates could not be determined from many studies, which could not be attributed to study designs. Average rates for intracranial complications were 3.8% among studies (per-study analysis) and 3.4% for pooled analysis of patients from different studies (per-patient analysis). Annual hardware removal rates were 3.6 and 2.4% for per-study and per-patient analysis, respectively, and lead revision rates were 4.1 and 2.6%, respectively. There was significant heterogeneity between studies (I² ranged between 77% and 91% for the three categories; p< 0.0001). For hardware removal heterogeneity (I² = 87.4%) was reduced by taking study size (p< 0.0001) and publication year (p< 0.01) into account, although a significant degree of heterogeneity remained (I² = 80.0%; p< 0.0001). Based on comparisons with health care-related databases there appears to be publication bias with lower rates for hardware-related AEs in published patient cohorts.

Conclusions

The proposed categories are suited for an unequivocal assessment of AEs even in a retrospective manner and useful for benchmarking. AE rates in the present cohorts from our institution compare favorable with the literature.

Experience Reduces Surgical and Hardware-Related Complications of Deep Brain Stimulation Surgery: A Single-Center Study of 181 Patients Operated in Six Years

Objective

Deep brain stimulation (DBS) surgery has increasingly been performed for the treatment of movement disorders and is associated with a wide array of complications. We aimed to present our experience and discuss strategies to minimize adverse events in light of this contemporary series and others in the literature.

Methods

A retrospective chart review was conducted to collect data on age, sex, indication, operation date, surgical technique, and perioperative and late complications.

Results

A total of 181 patients (113 males, 68 females) underwent DBS implantation surgery (359 leads) in the past six years. Indications and targets were as follows: Parkinson's disease (STN) (n=159), dystonia (GPi) (n=13), and essential tremor (Vim) (n=9). Mean age was 55.2 ± 11.7 (range 9-74) years. Mean follow-up duration was 3.4 ± 1.6 years. No mortality or permanent morbidity was observed. Major perioperative complications were confusion (6.6%), intracerebral hemorrhage (2.2%), stroke (1.1%), and seizures (1.1%). Long-term adverse events included wound (7.2%), mostly infection, and hardware-related (5.5%) complications. Among several factors, only surgical experience was found to be related with overall complication rates (early period: 31% versus late period: 10%; p=0.001).

Conclusion

The rates of both early and late complications of DBS surgery are acceptably low and decrease significantly with cumulative experience.

Bacterial colonisation of suture material after routine neurosurgical procedures: relevance for wound infection

BACKGROUND

Wound healing impairment is a serious problem in surgical disciplines which may be associated with chronic morbidity, increased cost and patient discomfort. Here we aimed to investigate the relevance of bacterial colonisation on suture material using polymerase chain reaction (PCR) to detect and taxonomically classify bacterial DNA in patients with and without wound healing problems after routine neurosurgical procedures.

METHODS

Repeat surgery was performed in 25 patients with wound healing impairment and in 38 patients with well-healed wounds. To determine the presence of bacteria, a 16S rDNA-based PCR detection method was applied. Fragments of 500 bp were amplified using universal primers which target hypervariable regions within the bacterial 16S rRNA gene. Amplicons were separated from each other by single-strand conformation polymorphism (SSCP) analysis, and finally classified using Sanger sequencing.

RESULTS

PCR/SSCP detected DNA of various bacteria species on suture material in 10/38 patients with well-healed wounds and in 12/25 patients with wound healing impairment including Staphylococcus aureus, Staphylococcus epidermidis, Propionibacterium acnes and Escherichia coli. Microbiological cultures showed bacterial growth in almost all patients with wound healing impairment and positive results in PCR/SSCP (10/12), while this was the case in only one patient with a well-healed wound (1/10).

CONCLUSIONS

Colonisation of suture material with bacteria occurs in a relevant portion of patients with and without wound healing impairment after routine neurosurgical procedures. Suture material may provide a nidus for bacteria and subsequent biofilm formation. Most likely, however, such colonisation of sutures is not a general primer for subsequent wound infection.

Advanced research on deep brain stimulation in treating mental disorders

Deep brain stimulation is a method that involves using an electric stimulus on a specific target in the brain with stereotaxis. It is a minimally invasive, safe, adjustable and reversible nerve involvement technology. At present, this technique is widely applied to treat movement disorders and has produced promising effects on mental symptoms, including combined anxiety and depression. Deep brain stimulation has therefore been employed as a novel treatment for depression, obsessive-compulsive disorder, habituation, Tourette's syndrome, presenile dementia, anorexia nervosa and other refractory mental illnesses. Many encouraging results have been reported. The aim of the present review was to briefly describe the mechanisms, target selection, side effects, ethical arguments and risks associated with deep brain stimulation. Although deep brain stimulation is a developing and promising treatment, a large amount of research is still required to determine its curative effect, and the selection of patients and targets must be subjected to strict ethical standards.

A new model for biofilm formation and inflammatory tissue reaction: intraoperative infection of a cranial implant with Staphylococcus aureus in rats

BACKGROUND

Implant failure is a severe and frequent adverse event in all areas of neurosurgery. It often involves infection with biofilm formation, accompanied by inflammation of surrounding tissue, including the brain, and bone loss. The most common bacteria involved are Staphylococcus aureus. We here test whether intraoperative infection of intracranial screws with Staphylococcus aureus would lead to biofilm formation and inflammatory tissue reaction in rats.

METHODS

Two titanium screws were implanted in the cranium of Sprague-Dawley rats, anesthetized with xylazine (4 mg/kg) and ketamine (75 mg/kg). Prior to the implantation of the screws, Staphylococcus aureus was given in the drill holes; controls received phosphate-buffered saline (PBS). Rats were euthanized 2, 10 and 21 days after surgery to remove the screws for analysis of biofilm formation with a confocal laser scanning microscope. The surrounding tissue composed of soft tissue and bone, as well as the underlying brain tissue, was evaluated for inflammation, bone remodeling, foreign body reaction and fibrosis after H&E staining.

RESULTS

Intraoperative application of Staphylococcus aureus leads to robust and stable biofilm formation on the titanium implants on days 10 and 21 after surgery, while no bacteria were found in controls. This was accompanied by a substantial inflammatory response of peri-implant tissue after infection, also affecting the underlying brain tissue.

CONCLUSIONS

Intraoperative infection of implants with Staphylococcus aureus in rats may be useful as a tool to model new implant materials and surfaces on biofilm formation and inflammatory tissue reaction in vivo.