Hardware-related complications of deep brain stimulation: a ten year experience

Delirium after deep brain stimulation for Parkinson's disease: a meta-analysis of incidence and risk factors

Deep brain stimulation (DBS) is a valuable treatment for Parkinson's disease (PD), but postoperative delirium (POD) is a common complication. Understanding the risk factors for POD is crucial for optimizing patient selection and developing preventative measures. This systematic review and meta-analysis aims to identify predictors of POD in PD patients undergoing DBS surgery. We conducted a comprehensive search of four major databases for cohort studies on POD in patients undergoing DBS for PD, up to June 2024. Two reviewers independently screened studies, assessed the risk of bias using the Newcastle-Ottawa Scale, and extracted data. Meta-analysis was conducted using Review Manager, with heterogeneity assessed the I2 statistic and chi-square p value. Subgroup and sensitivity analyses were also performed to explore the consistency of findings. Eleven studies, including 1,368 patients, were analyzed to determine the incidence of POD in PD patients undergoing DBS. The incidence of POD in PD patients undergoing DBS, which was found to be 21% (95% CI: [14.6%, 27.4%]). Age, Mini-Mental State Examination (MMSE), and Non-Motor Symptom Scale (NMSS) were significant predictors, with effect sizes of (OR = 1.10, 95% CI: [1.06, 1.15], P < 0.00001), (OR = 0.85, 95% CI: [0.72, 1.00], P = 0.05), and (OR = 1.01, 95% CI: [1.00, 1.02], P = 0.04), respectively. However, gender, UPDRS-III ON score, brain atrophy, diabetes, Hamilton Anxiety Score (HAMA), operation time, disease duration, BMI, and cerebral infarction were not significant predictors. This meta-analysis suggests that age, cognitive function, and non-motor symptoms are important factors associated with POD patients undergoing DBS surgery. Further research with larger sample sizes and diverse populations is needed to confirm these findings and identify more specific predictors.

Managing Lead Fractures in Deep Brain Stimulation for Movement Disorders: A Decade-Long Case Series from a National Neurosurgical Centre

Background: Deep brain stimulation (DBS) is an effective treatment for movement disorders, but its long-term efficacy may be undermined by hardware complications such as lead fractures. These complications increase healthcare costs and necessitate surgical revisions. The frequency, timing, and clinical factors associated with lead fractures remain poorly understood. Objective: This study aimed to determine the incidence, timing, and clinical factors associated with lead fractures in a large cohort of DBS patients over a 10-year period. Methods: This retrospective study analyzed data from 325 patients who underwent bilateral DBS implantation at the National Centre for Neurosurgery from 2013 to 2023. The analysis specifically focused on 17 patients who experienced lead fractures during the long-term follow-up period. Results: Among the 325 patients, lead fractures were identified in 17 patients (5.23%), affecting 18 electrodes. The majority of cases involved patients with Parkinson's disease (76.5%) or dystonia (23.5%), with an average age of 59.17 ± 8.77 years. Nearly all patients with lead fractures had a history of trauma. Additionally, two cases were associated with active engagement in sports, particularly activities involving movements like pulling up on a horizontal bar, while Twiddler's Syndrome was identified in two other cases. All electrode fractures required surgical revision. Conclusions: Lead fractures, while rare, remain a significant complication in DBS systems. Precise surgical techniques, early detection, and advancements in DBS hardware design may help to mitigate this risk. Future innovations, such as durable leads or wireless systems, may improve long-term outcomes in DBS therapy for movement disorders.

Therapeutic Measures for Infections Originating from Scalp Incisions Following Deep Brain Stimulation in Patients with Parkinson's Disease

BACKGROUND

Deep brain stimulation (DBS) is a well-established treatment for Parkinson's disease (PD). However, infection following DBS surgery is a serious complication that can lead to the recurrence and worsening of Parkinson's symptoms or related hardware reimplantation, causing considerable patient suffering and financial burden.

OBJECTIVE

This study aims to compare the therapeutic efficiency of different treatment approaches for scalp incision infections after DBS surgery in PD patients.

METHODS

We conducted a retrospective review of patients with PD who experienced scalp infections following DBS at our hospital between January 2017 and December 2021. The patients were divided into 2 groups based on whether affected implants were removed or not. Fisher's exact test was applied to compare the reinfection rates between groups A and B.

RESULTS

In group A, 4 patients underwent debridement only, and all of them experienced reinfection between 2 and 25 months after the initial treatment. In group B, 9 patients underwent debridement and removal of potentially affected implants. Among them, 8 patients underwent reimplantation of the DBS device within 3-6 months after the initial treatment, and no cases of reinfection occurred. However, 1 patient experienced reinfection in the postauricular incision and percutaneous tunnel 5 months after the initial treatment, resulting in the complete removal of the entire DBS system. The reinfection rate in group B (11.11%) was significantly lower than that in group A (100%, P = 0.007).

CONCLUSIONS

Scalp incision infections following DBS surgery can affect deep tissues, and the implementation of a comprehensive treatment strategy involving local debridement and removal of potentially affected implants can significantly reduce the risk of infection recurrence and its spread.

Neuromodulation for neuropathic pain

The treatment of neuropathic pain (NeP) often leads to partial or incomplete pain relief, with up to 40 % of patients being pharmaco-resistant. In this chapter the efficacy of neuromodulation techniques in treating NeP is reviewed. It presents a detailed evaluation of the mechanisms of action and evidence supporting the clinical use of the most common approaches like transcutaneous electrical nerve stimulation (TENS), transcranial direct current stimulation (tDCS), repetitive transcranial magnetic stimulation (rTMS), deep brain stimulation (DBS), invasive motor cortex stimulation (iMCS), spinal cord stimulation (SCS), dorsal root ganglion stimulation (DRG-S), and peripheral nerve stimulation (PNS). Current literature suggests that motor cortex rTMS is effective for peripheral and central NeP, and TENS for peripheral NeP. Evidence for tDCS is inconclusive. DBS is reserved for research settings due to heterogeneous results, while iMSC has shown efficacy in a small randomized trial in neuropathic pain due to stroke and brachial plexus avulsion. SCS has moderate evidence for painful diabetic neuropathy and failed back surgery syndrome, but trials were not controlled with sham. DRG-S and PNS have shown positive results for complex regional pain syndrome and post-surgical neuropathic pain, respectively. Adverse effects vary, with non-invasive techniques showing local discomfort, dizziness and headache, and DBS and SCS hardware-related issues. To date, non-invasive techniques have been more extensively studied and some are included in international guidelines, while the evidence level for invasive techniques are less robust, potentially suggesting their use in a case-by-case indication considering patient´s preferences, costs and expected benefits.

Cost-effectiveness and threshold analysis of deep brain stimulation vs. treatment-as-usual for treatment-resistant depression

Treatment-resistant depression (TRD) affects approximately 2.8 million people in the U.S. with estimated annual healthcare costs of $43.8 billion. Deep brain stimulation (DBS) is currently an investigational intervention for TRD. We used a decision-analytic model to compare cost-effectiveness of DBS to treatment-as-usual (TAU) for TRD. Because this therapy is not FDA approved or in common use, our goal was to establish an effectiveness threshold that trials would need to demonstrate for this therapy to be cost-effective. Remission and complication rates were determined from review of relevant studies. We used published utility scores to reflect quality of life after treatment. Medicare reimbursement rates and health economics data were used to approximate costs. We performed Monte Carlo (MC) simulations and probabilistic sensitivity analyses to estimate incremental cost-effectiveness ratios (ICER; USD/quality-adjusted life year [QALY]) at a 5-year time horizon. Cost-effectiveness was defined using willingness-to-pay (WTP) thresholds of $100,000/QALY and $50,000/QALY for moderate and definitive cost-effectiveness, respectively. We included 274 patients across 16 studies from 2009-2021 who underwent DBS for TRD and had ≥12 months follow-up in our model inputs. From a healthcare sector perspective, DBS using non-rechargeable devices (DBS-pc) would require 55% and 85% remission, while DBS using rechargeable devices (DBS-rc) would require 11% and 19% remission for moderate and definitive cost-effectiveness, respectively. From a societal perspective, DBS-pc would require 35% and 46% remission, while DBS-rc would require 8% and 10% remission for moderate and definitive cost-effectiveness, respectively. DBS-pc will unlikely be cost-effective at any time horizon without transformative improvements in battery longevity. If remission rates ≥8-19% are achieved, DBS-rc will likely be more cost-effective than TAU for TRD, with further increasing cost-effectiveness beyond 5 years.

The deep and the deeper: Spinal cord and deep brain stimulation for neuropathic pain

Neuropathic pain occurs in people experiencing lesion or disease affecting the somatosensorial system. It is present in 7 % of the general population and may not fully respond to first- and second-line treatments in up to 40 % of cases. Neuromodulation approaches are often proposed for those not tolerating or not responding to usual pharmacological management. These approaches can be delivered surgically (invasively) or non-invasively. Invasive neuromodulation techniques were the first to be employed in neuropathic pain. Among them is spinal cord stimulation (SCS), which consists of the implantation of epidural electrodes over the spinal cord. It is recommended in some guidelines for peripheral neuropathic pain. While recent studies have called into question its efficacy, others have provided promising data, driven by advances in techniques, battery capabilities, programming algorithms and software developments. Deep brain stimulation (DBS) is another well-stablished neuromodulation therapy routinely used for movement disorders; however, its role in pain management remains limited to specific research centers. This is not only due to variable results in the literature contesting its efficacy, but also because several different brain targets have been explored in small trials, compromising comparisons between these studies. Structures such as the periaqueductal grey, posterior thalamus, anterior cingulate cortex, ventral striatum/anterior limb of the internal capsule and the insula are the main targets described to date in literature. SCS and DBS present diverse rationales for use, mechanistic backgrounds, and varying levels of support from experimental studies. The present review aims to present their methodological details, main mechanisms of action for analgesia and their place in the current body of evidence in the management of patients with neuropathic pain, as well their particularities, effectiveness, safety and limitations.

General Treatments Promoting Independent Living in Parkinson's Patients and Physical Therapy Approaches for Improving Gait-A Comprehensive Review

This study delves into the multifaceted approaches to treating Parkinson's disease (PD), a neurodegenerative disorder primarily affecting motor function but also manifesting in a variety of symptoms that vary greatly among individuals. The complexity of PD symptoms necessitates a comprehensive treatment strategy that integrates surgical interventions, pharmacotherapy, and physical therapy to tailor to the unique needs of each patient. Surgical options, such as deep brain stimulation (DBS), have been pivotal for patients not responding adequately to medication, offering significant symptom relief. Pharmacotherapy remains a cornerstone of PD management, utilizing drugs like levodopa, dopamine agonists, and others to manage symptoms and, in some cases, slow down disease progression. However, these treatments often lead to complications over time, such as motor fluctuations and dyskinesias, highlighting the need for precise dosage adjustments and sometimes combination therapies to optimize patient outcomes. Physical therapy plays a critical role in addressing the motor symptoms of PD, including bradykinesia, muscle rigidity, tremors, postural instability, and akinesia. PT techniques are tailored to improve mobility, balance, strength, and overall quality of life. Strategies such as gait and balance training, strengthening exercises, stretching, and functional training are employed to mitigate symptoms and enhance functional independence. Specialized approaches like proprioceptive neuromuscular facilitation (PNF), the Bobath concept, and the use of assistive devices are also integral to the rehabilitation process, aimed at improving patients' ability to perform daily activities and reducing the risk of falls. Innovations in technology have introduced robotic-assisted gait training (RAGT) and other assistive devices, offering new possibilities for patient care. These tools provide targeted support and feedback, allowing for more intensive and personalized rehabilitation sessions. Despite these advancements, high costs and accessibility issues remain challenges that need addressing. The inclusion of exercise and activity beyond structured PT sessions is encouraged, with evidence suggesting that regular physical activity can have neuroprotective effects, potentially slowing disease progression. Activities such as treadmill walking, cycling, and aquatic exercises not only improve physical symptoms but also contribute to emotional well-being and social interactions. In conclusion, treating PD requires a holistic approach that combines medical, surgical, and therapeutic strategies. While there is no cure, the goal is to maximize patients' functional abilities and quality of life through personalized treatment plans. This integrated approach, along with ongoing research and development of new therapies, offers hope for improving the management of PD and the lives of those affected by this challenging disease.

Advances in Wireless, Batteryless, Implantable Electronics for Real-Time, Continuous Physiological Monitoring

This review summarizes recent progress in developing wireless, batteryless, fully implantable biomedical devices for real-time continuous physiological signal monitoring, focusing on advancing human health care. Design considerations, such as biological constraints, energy sourcing, and wireless communication, are discussed in achieving the desired performance of the devices and enhanced interface with human tissues. In addition, we review the recent achievements in materials used for developing implantable systems, emphasizing their importance in achieving multi-functionalities, biocompatibility, and hemocompatibility. The wireless, batteryless devices offer minimally invasive device insertion to the body, enabling portable health monitoring and advanced disease diagnosis. Lastly, we summarize the most recent practical applications of advanced implantable devices for human health care, highlighting their potential for immediate commercialization and clinical uses.

Complications of deep brain stimulation in Parkinson's disease: a single-center experience of 517 consecutive cases

BACKGROUND

The number of deep brain stimulation (DBS) procedures is rapidly rising as well as the novel indications. Reporting adverse events related to surgery and to the hardware used is essential to define the risk-to-benefit ratio and develop novel strategies to improve it.

OBJECTIVE

To analyze DBS complications (both procedure-related and hardware-related) and further assess potential predictive factors.

METHODS

Five hundred seventeen cases of DBS for Parkinson's disease were performed between 2006 and 2021 in a single center (mean follow-up: 4.68 ± 2.86 years). Spearman's Rho coefficient was calculated to search for a correlation between the occurrence of intracerebral hemorrhage (ICH) and the number of recording tracks. Multiple logistic regression analyzed the probability of developing seizures and ICH given potential risk factors. Kaplan-Meier curves were performed to analyze the cumulative proportions of hardware-related complications.

RESULTS

Mortality rate was 0.2%, while permanent morbidity 0.6%. 2.5% of cases suffered from ICH which were not influenced by the number of tracks used for recordings. 3.3% reported seizures that were significantly affected by perielectrode brain edema and age. The rate of perielectrode brain edema was significantly higher for Medtronic's leads compared to Boston Scientific's (Χ2(1)= 5.927, P= 0.015). 12.2% of implants reported Hardware-related complications, the most common of which were wound revisions (7.2%). Internal pulse generator models with smaller profiles displayed more favorable hardware-related complication survival curves compared to larger designs (X2(1)= 8.139, P= 0.004).

CONCLUSION

Overall DBS has to be considered a safe procedure, but future research is needed to decrease the rate of hardware-related complications which may be related to both the surgical technique and to the specific hardware's design. The increased incidence of perielectrode brain edema associated with certain lead models may likewise deserve future investigation.

Deep brain stimulation, lesioning, focused ultrasound: update on utility

Procedures for neurological disorders such as Parkinsons Disease (PD), Essential Tremor (ET), Obsessive Compulsive Disorder (OCD), Tourette's Syndrome (TS), and Major Depressive Disorder (MDD) tend to overlap. Common therapeutic procedures include deep brain stimulation (DBS), lesioning, and focused ultrasound (FUS). There has been significant change and innovation regarding targeting mechanisms and new advancements in this field allowing for better clinical outcomes in patients with severe cases of these conditions. In this review, we discuss advancements and recent discoveries regarding these three procedures and how they have led to changes in utilization in certain conditions. We further discuss the advantages and drawbacks of these treatments in certain conditions and the emerging advancements in brain-computer interface (BCI) and its utility as a therapeutic for neurological disorders.

Skin-related complications following deep brain stimulation surgery: A single-center retrospective analysis of 525 patients who underwent DBS surgery

BACKGROUND

Although Deep Brain Stimulation (DBS) is a safe and proven treatment modality for patients suffering from debilitating movement and neuropsychiatric disorders, it is not free from complications. Management of skin erosion and infection following DBS surgery constitutes a challenge in everyday clinical practice.

OBJECTIVES

Skin-related complications were evaluated in patients who underwent DBS surgery due to Parkinson's disease (PD), dystonia, essential tremor (ET), and other indications including Tourette syndrome (TS), Obsessive-Compulsive Disorder (OCD), and epilepsy.

METHODS

A retrospective analysis of clinical data was performed on patients who underwent DBS surgery between November 2008 and September 2021 at the Department of Neurosurgery, Institute of Psychiatry and Neurology, Warsaw.

RESULTS

525 patients who underwent 927 DBS leads implantations were included in the analysis. There were 398 patients with PD, 80 with dystonia, 26 with ET, 7 with drug-resistant epilepsy, 5 with Multiple Sclerosis, 4 with Holme's or cerebellar tremor, 3 with TS, and 2 with OCD. 42 patients (8,0%) had 78 skin infection episodes. The overall level of skin erosion was 3,8% (20/525 patients). The risk of developing infection episode was connected with younger age at diagnosis (p = 0.017) and at surgery (p = 0.023), whereas the development of skin erosion was connected with the dystonia diagnosis (p = 0.012). Patients with dystonia showed the highest rate of infections and erosions (11/70 and 7/70 patients retrospectively).

DISCUSSION

Postoperative skin complications are a serious side effect of DBS surgery.

CONCLUSION

Our study suggests that dystonic patients are at higher risk of developing skin-related complications after DBS surgery.

Evaluation of Deep Brain Stimulation (DBS) Lead Biomechanical Interaction with Brain Tissue

The current study aims to examine the effect of material properties on implanted leads used for deep brain stimulation (DBS) using finite element (FE) analysis to investigate brain deformation around an implanted DBS lead in response to daily head accelerations. FE analysis was used to characterize the relative motion of the DBS lead in a suite of fifteen cases sampled from a previously derived kinematic envelope representative of everyday activities describing translational and rotational pulse shape, magnitude, and duration. Load curves were applied to the atlas-based brain model (ABM) with a scaled Haversine acceleration pulse in four directions of rotation: + X, - Y, + Y, and + Z. In addition to the fifteen sampled cases, six experimental cases taken from a previous literature review were also simulated for comparison. The current investigation found that there was very little difference in brain response for the DBS leads with two different material properties. In general, the brain and DBS lead experienced the greatest deformation during rotation about the Z axis for similar load cases. In conclusion, this study showed that there was no significant difference in implanted DBS lead deformation based on lead material properties.

Complications of Deep Brain Stimulation for Movement Disorders: Literature Review and Personal Experience

The contemporary technique of deep brain stimulation (DBS) is very effective for management of movement disorders-including Parkinson's disease, generalized dystonia, and tremors-and has also been successfully applied for novel indications (e.g., intractable epilepsy and chronic pain). As a result, growing numbers of DBS procedures have been performed worldwide; correspondingly, the incidence of associated morbidity has also increased. All complications of DBS can be divided into those associated with (1) the surgical procedure, (2) the device itself, and (3) the applied electrical stimulation. On the basis of an analysis of the available literature and the personal experience of the author, it may be concluded that implantation of a DBS device is a relatively safe procedure accompanied by very low risks of major morbidity or a permanent neurological deficit. Nevertheless, awareness of the possible complications and application of appropriate preventive measures for their avoidance are very important for providing safe and effective treatment.

Recrudescent infection after deep brain stimulator reimplantation

OBJECTIVE

The efficacy of deep brain stimulation (DBS) in treating the symptoms of movement disorders can be life changing for patients. Thus, the 5%-15% incidence of stimulator-related infection requiring removal of the device can be particularly disheartening. Although DBS system reimplantation is generally successful, this is not always the case. The literature is replete with publications describing the incidence of infection and the associated features. However, the literature is sparse in terms of information on the incidence of recurrent or recrudescent infection after system reimplantation. The goal of this paper was to evaluate factors leading to unsuccessful reimplantation of a DBS system following initial infection.

METHODS

Data were reviewed for all DBS procedures performed by one surgeon (K.L.H.) over 19 years including the infectious agent, location of infection, treatment regimen, and subsequent reimplantation of a DBS system and long-term outcome.

RESULTS

In this series of 558 patients who had undergone DBS surgery, 37 (6.6%) subsequently developed an infection. Infections with methicillin-sensitive Staphylococcus aureus, Enterobacter species, or coagulase-negative staphylococci were predominant. Four patients had cerebritis, one had meningitis, and the rest had soft tissue infections of the pocket or scalp. All had their entire DBS system explanted, followed by 4-6 weeks of intravenous antibiotics and surveillance for recrudescence for an additional period of at least 30 days. Twenty-five patients subsequently underwent DBS system reimplantation, and the procedure was successful in 22. Three of the 4 patients with cerebritis developed a subsequent wound infection after system reimplantation. None of the other 22 patients developed a recurrence. The odds ratio for developing a recurrent infection after cerebritis was 28.5 (95% CI 1.931-420.5, p = 0.007).

CONCLUSIONS

This study, the largest series of DBS system reimplantations following infection, demonstrated that most patients can have successful reimplantations without recurrent infection. However, patients who have had DBS-related cerebritis have a nearly 30-fold increased risk of developing reinfection after reimplantation. Alternative strategies for these patients are discussed.

Deep brain stimulation of the subthalamic nucleus for epilepsy

Deep brain stimulation of the subthalamic nucleus (STN-DBS) is a promising palliative option for patients with refractory epilepsy. However, crucial questions remain unanswered: Which patients are the optimal candidates? How, where, and when to stimulate the STN? And what is the mechanism of STN-DBS action on epilepsy? Thus, we reviewed the clinical evidence on the antiepileptic effects of STN-DBS and its possible mechanisms on drug-resistant epilepsy, its safety, and the factors influencing stimulation outcomes. This information may guide clinical decision-making. In addition, based on the current knowledge on the effect of STN-DBS on epilepsy, we suggest research that needs to be carried out in the future.

Achieving long-term stability of thin-film electrodes for neurostimulation

Implantable electrodes that can reliably measure brain activity and deliver an electrical stimulus to a target tissue are increasingly employed to treat various neurological diseases and neuropsychiatric disorders. Flexible thin-film electrodes have gained attention over the past few years to minimise invasiveness and damage upon implantation. Research has previously focused on optimising the electrode's electrical and mechanical properties; however, their chronic stability must be validated to translate electrodes from a research to a clinical application. Neurostimulation electrodes, which actively inject charge, have yet to reliably demonstrate continuous functionality for ten years or more in vivo, the accepted metric for clinical viability. Long-term stability can only be achieved if the focus switches to investigating how and why such devices fail. Unfortunately, there is a field-wide reluctance to investigate device stability and failures, which hinders device optimisation. This review surveys thin-film electrode designs with a focus on adhesion between electrode layers and the interactions with the surrounding environment. A comprehensive summary of the abiotic failure modes faced by such electrodes is presented, and to encourage investigation, systematic methods for analysing their origin are recommended. Finally, approaches to reducing the likelihood of device failure are offered. STATEMENT OF SIGNIFICANCE: Neural electrodes that can deliver an electrical stimulus to a target tissue are widely used to treat various neurological diseases. Essential to the function of these electrodes is the ability to safely stimulate the target tissue for extended periods (> 10 years); however, this has not yet been clinically achieved. The key to achieving long-term stability is an increased understanding of electrode interactions with the surrounding tissue and subsequent systematic analysis of their failure modes. This review highlights the need for a change in the approach to investigating electrode failure, and in doing so summarizes the common ways in which neural electrodes fail, methods for identifying them and approaches to preventing them.

Surgical and Hardware-Related Adverse Events of Deep Brain Stimulation: A Ten-Year Single-Center Experience

INTRODUCTION

Although deep brain stimulation (DBS) is effective for treating a number of neurological and psychiatric indications, surgical and hardware-related adverse events (AEs) can occur that affect quality of life. This study aimed to give an overview of the nature and frequency of those AEs in our center and to describe the way they were managed. Furthermore, an attempt was made at identifying possible risk factors for AEs to inform possible future preventive measures.

MATERIALS AND METHODS

Patients undergoing DBS-related procedures between January 2011 and July 2020 were retrospectively analyzed to inventory AEs. The mean follow-up time was 43 ± 31 months. Univariate logistic regression analysis was used to assess the predictive value of selected demographic and clinical variables.

RESULTS

From January 2011 to July 2020, 508 DBS-related procedures were performed including 201 implantations of brain electrodes in 200 patients and 307 implantable pulse generator (IPG) replacements in 142 patients. Surgical or hardware-related AEs following initial implantation affected 40 of 200 patients (20%) and resolved without permanent sequelae in all instances. The most frequent AEs were surgical site infections (SSIs) (9.95%, 20/201) and wire tethering (2.49%, 5/201), followed by hardware failure (1.99%, 4/201), skin erosion (1.0%, 2/201), pain (0.5%, 1/201), lead migration (0.52%, 2/386 electrode sites), and hematoma (0.52%, 2/386 electrode sites). The overall rate of AEs for IPG replacement was 5.6% (17/305). No surgical, ie, staged or nonstaged, electrode fixation, or patient-related risk factors were identified for SSI or wire tethering.

CONCLUSIONS

Major AEs including intracranial surgery-related AEs or AEs requiring surgical removal or revision of hardware are rare. In particular, aggressive treatment is required in SSIs involving multiple sites or when Staphylococcus aureus is identified. For future benchmarking, the development of a uniform reporting system for surgical and hardware-related AEs in DBS surgery would be useful.

MR Conditionality of Abandoned Leads from Active Implantable Medical Devices at 1.5T

During Magnetic Resonance (MR) scans, abandoned leads from active implantable medical devices (AIMDs) can experience excessive heating near the lead-tip, depending on the types of termination applied to the proximal end. The influence of different proximal treatments, i.e., (i) freely exposed in the tissue, (ii) capped with metallic material, and (iii) capped with plastic material on the RF-induced heating are studied. Abandoned leads from a sacral neuromodulation (SNM) system were investigated in this study. The device models, i.e., the transfer functions, for different proximal treatments were developed. These models are then used to assess the in-vivo lead-tip heating inside four virtual human models (FATS, Duke, Ella, and Billie). The RF-induced heating from these abandoned leads with different proximal end treatments are compared with the lead-tip heating of the original AIMD system. The maximum lead-tip heating for abandoned leads using metal cap at the proximal end is lower than that from the original intact AIMD system. Abandoned leads with plastic cap treatment at the proximal end will lead to an average in-vivo temperature that is 3.5 times higher than that from the original intact AIMD system. Therefore, from this study and in terms of the RF-induced heating, the abandoned leads with metallic cap treatment at the proximal end can maintain the MR conditionality of the original AIMD system.Clinical Relevance- The different treatments of proximal end of the abandoned leads from AIMD are studied to ensure that MR Conditional AIMD leads remain MR Conditional when the leads are abandoned in the patients.

Implantable Pulse Generators for Deep Brain Stimulation: Challenges, Complications, and Strategies for Practicality and Longevity

Deep brain stimulation (DBS) represents an important treatment modality for movement disorders and other circuitopathies. Despite their miniaturization and increasing sophistication, DBS systems share a common set of components of which the implantable pulse generator (IPG) is the core power supply and programmable element. Here we provide an overview of key hardware and software specifications of commercially available IPG systems such as rechargeability, MRI compatibility, electrode configuration, pulse delivery, IPG case architecture, and local field potential sensing. We present evidence-based approaches to mitigate hardware complications, of which infection represents the most important factor. Strategies correlating positively with decreased complications include antibiotic impregnation and co-administration and other surgical considerations during IPG implantation such as the use of tack-up sutures and smaller profile devices.Strategies aimed at maximizing battery longevity include patient-related elements such as reliability of IPG recharging or consistency of nightly device shutoff, and device-specific such as parameter delivery, choice of lead configuration, implantation location, and careful selection of electrode materials to minimize impedance mismatch. Finally, experimental DBS systems such as ultrasound, magnetoelectric nanoparticles, and near-infrared that use extracorporeal powered neuromodulation strategies are described as potential future directions for minimally invasive treatment.

Magnetic resonance conditionality of abandoned leads from active implantable medical devices at 1.5 T

PURPOSE

During MR scans, abandoned leads from active implantable medical devices (AIMDs) can experience excessive heating at the lead tip, depending on the type of termination applied to the proximal contacts (proximal end treatment). The influence of different proximal end treatments (ie, [1] freely exposed in the tissue, [2] terminated with metal in contact with the tissue, or [3] capped with plastic, and thereby fully insulated, on the RF-induced lead-tip heating) are studied. A technique to ensure that MR Conditional AIMD leads remain MR Conditional even when abandoned is recommended.

METHODS

Abandoned leads from three MR Conditional AIMDs ([1] a sacral neuromodulation system, [2] a cardiac rhythm management pacemaker system, and [3] a deep brain stimulator system) were investigated in this study. The computational lead models (ie, the transfer functions) for different proximal end treatments were measured and used to assess the in vivo lead-tip heating for four virtual human models (FATS, Duke, Ella, and Billie) and compared with the lead-tip heating of the complete MR Conditional AIMD system.

RESULT

The average and maximum lead-tip heating for abandoned leads proximally capped with metal is always lower than that from the complete AIMD system. Abandoned leads proximally insulated could lead to an average in vivo temperature rise up to 3.5 times higher than that from the complete AIMD system.

CONCLUSION

For the three investigated AIMDs under 1.5T MR scanning, our results indicate that RF-induced lead-tip heating of abandoned leads strongly depends on the proximal lead termination. A metallic cap applied to the proximal termination of the tested leads could significantly reduce the RF-induced lead-tip heating.

Vacuum-Assisted Closure with Temporalis Muscle Reconstruction for Recurrent Scalp Erosion Following Deep Brain Stimulation: A Case Report

BACKGROUND

Scalp erosion is not an uncommon complication of deep brain stimulation (DBS) surgery. Although various methods have been proposed to prevent and manage complications, there are still challenges. We introduce a case of recurrent scalp erosion after DBS surgery treated with vacuum-assisted closure.

CASE DESCRIPTION

This article reports the case of a patient who underwent DBS for advanced Parkinson's disease and suffered from recurrent scalp erosion with device extrusion through the skin. Scalp erosion occurred 2 years after DBS and repeated improvement and deterioration despite scalp reconstruction using a skin flap. We opened the wound and performed temporal muscle reconstruction to cover the burr hole site, and we changed the exposed cable and applied vacuum-assisted closure. During the follow-up period, no signs of erosion or infection occurred, and DBS efficacy was preserved.

CONCLUSION

To date, the available management strategies for scalp erosion after DBS are revision with debridement and scalp reconstruction using skin flaps or skin grafts. However, if erosion occurs repeatedly despite the above management strategies, vacuum-assisted closure with temporalis muscle reconstruction could be a suitable option. We suggest that if the condition of the scalp is weakened, it is worth considering this approach preferentially.

Focused Ultrasound Thalamotomy for the Treatment of Essential Tremor: A 2-Year Outcome Study of Chinese People

Background: Essential tremor (ET) is a common movement disorder among elderly individuals worldwide and is occasionally associated with a high risk for mild cognitive impairment and dementia. This retrospective study aimed to determine the clinical outcome of unilateral magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy in Chinese patients with ET. Methods: In total, 31 male and 17 female patients with drug-refractory ET were enrolled in this research study from January 2017 to September 2019. The severity of tremor and disability were assessed using the Clinical Rating Scale for Tremor (CRST) within a 2-year follow-up period. Results: The mean age of the participants was 59.14 ± 13.5 years. The mean skull density ratio (SDR) was 0.5 ± 0.1. The mean highest temperature was 57.0 ± 2.4°C. The mean number of sonications was 10.0 ± 2.6. The average maximum energy was 19,710.5 ± 8,624.9 J. The total CRST scores and sub-scores after MRgFUS thalamotomy significantly reduced during each follow-up (p < 0.001). All but four (8.3%) of the patients had reversible adverse events (AEs) after the procedure. Conclusions: MRgFUS had sustained clinical efficacy 2 years after treatment for intractable ET. Only few patients presented with thalamotomy-related AEs including numbness, weakness, and ataxia for an extended period. Most Chinese patients were treated safely and effectively despite their low SDR.

Patient-Centered Identification of Meaningful Regulatory Endpoints for Medical Devices to Treat Parkinson's Disease

Introduction. A growing literature has developed on identifying outcomes that matter to patients. This study demonstrates an approach involving patient and regulatory perspectives to identify outcomes that are meaningful in the context of medical devices for Parkinson’s disease (PD). Methods. A systematic process was used for specifying relevant regulatory endpoints by synthesizing inputs of various sources and stakeholders. First, a literature review was conducted to identify important benefits, risks, and other considerations for medical devices to treat PD; patient discussion groups (n = 6) were conducted to refine the list of considerations, followed by a survey (n = 29) to prioritize them; and patient and Food and Drug Administration (FDA) reviewers informed specification of the final endpoints. Two FDA clinicians gave clinical and regulatory perspectives at each step. Results. Movement symptoms were ranked as most important (ranked 1 or 2 by 72% of participants) and psychological and cognitive symptoms as the next most important (ranked 1 or 2 by 52% of participants). Within movement symptoms, falls, impaired movement, bradykinesia, resting tremor, stiffness, and rigidity were ranked highly. Overall, nine attributes were identified and prioritized as patient-centric for use in clinical trial design and quantitative patient preference studies. These attributes were benefits and risks related to therapeutics for PD as well as other considerations, including time until a medical device is available for patient use. Discussion. This prospective approach identified meaningful and relevant benefits, risks, and other considerations that may be used for clinical trial design and quantitative patient preference studies. Although PD was the focus of this study, the approach can be used to study patient perspectives about other disease or treatment areas.

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.

Lesser-Known Aspects of Deep Brain Stimulation for Parkinson's Disease: Programming Sessions, Hardware Surgeries, Residential Care Admissions, and Deaths

OBJECTIVE

The long-term treatment burden, duration of community living, and survival of patients with Parkinson's disease (PD) after deep brain stimulation (DBS) implantation are unclear. This study aims to determine the frequency of programming, repeat hardware surgeries (of the intracranial electrode, implantable pulse generator [IPG], and extension-cable), and the timings of residential care and death in patients with PD treated with DBS.

MATERIALS AND METHODS

In this cross-sectional, population-based study, individual-level data were collected from the Australian government covering a 15-year period (2002-2016) on 1849 patients with PD followed from DBS implantation.

RESULTS

The mean DBS implantation age was 62.6 years and mean follow-up 5.0 years. Mean annual programming rates were 6.9 in the first year and 2.8 in subsequent years. 51.4% of patients required repeat hardware surgery. 11.3% of patients had repeat intracranial electrode surgery (including an overall 1.1% of patients who were completely explanted). 47.6% of patients had repeat IPG/extension-cable surgery including for presumed battery depletion. 6.2% of patients had early repeat IPG/extension-cable surgery (within one year of any previous such surgery). Thirty-day postoperative mortality was 0.3% after initial DBS implantation and 0.6% after any repeat hardware surgery. 25.3% of patients were admitted into residential care and 17.4% died. The median interval to residential care and death was 10.2 years and 11.4 years, respectively. Age more than 65 years was associated with fewer repeat hardware surgeries for presumed complications (any repeat surgery of electrodes, extension-cables, and early IPG surgery) and greater rates of residential care admission and death.

CONCLUSIONS

Data from a large cohort of patients with PD treated with DBS found that the median life span after surgery is ten years. Repeat hardware surgery, including of the intracranial electrodes, is common. These findings support development of technologies to reduce therapy burden such as enhanced surgical navigation, hardware miniaturization, and improved battery efficiency.

Safety and efficacy of unilateral and bilateral pallidotomy for primary dystonia

Objective

Ablation of the globus pallidus internus (pallidotomy) is an effective surgical intervention for dystonia. However, the current literature on the efficacy and safety of pallidotomy for dystonia is derived only from single‐case reports and small cohort studies.

Methods

We retrospectively analyzed patients with primary dystonia who underwent pallidotomy at our institution between 2014 and 2019. Neurological conditions were evaluated using the Burke‐Fahn‐Marsden Dystonia Rating Scale (BFMDRS, range: 0–120). We evaluated the total BFMDRS score and each subitem score (nine body regions) in the patients who underwent unilateral and bilateral pallidotomy before surgery and at last available follow‐up. Moreover, postoperative complications were analyzed.

Results

We found that 69 and 20 patients underwent unilateral and bilateral pallidotomy respectively. The mean age at dystonia onset was 40.4 ± 15.2 years. The mean clinical follow‐up period was 17.2 ± 11.6 months. Unilateral pallidotomy significantly improved the total BFMDRS score from 11.2 ± 14.7 preoperatively to 5.4 ± 7.6 at last available follow‐up (51.8% improvement, p < 0.001). Furthermore, there was a significant and independent improvement in all midline BFMDRS subitems, including eyes, mouth, speech/swallow, and neck, after unilateral pallidotomy. Bilateral pallidotomy significantly improved the total BFMDRS score from 14.6 ± 10.2 preoperatively to 3.8 ± 8.2 at last available follow‐up (74.0% improvement, p < 0.001). However, bilateral pallidotomy induced medically refractory parkinsonism (postural instability and gait disturbance) in five patients, dysarthria in three patients, and dysphagia in one patient.

Interpretation

Unilateral radiofrequency pallidotomy remains a viable treatment option for patients with some forms of dystonia. Bilateral pallidotomy cannot be recommended due to unacceptably high complication rates.

A mechanical analysis informed fractography study on load-specific fatigue behaviors of Pt-Ir coils used in implantable medical leads

Fatigue fracture is a major threaten to implantable medical coils such as platinum-iridium (Pt-Ir) coils used in deep brain stimulation leads. The fractography under bending and torsion fatigue was studied in comparison with mechanical analysis to grasp load-specific fatigue characteristics and understand the mechanisms. Mechanical analysis of the coil under bending and torsion was conducted with both analytical and numerical methods. Pt-Ir coils were experimentally fatigued at roughly paralleled bending and torsional load levels. The fatigue life was recorded and the fracture morphology was observed and analyzed. It is revealed that the helical structure of the coil turns bending and torsion loads into different locally distributed stresses, which mainly determine the fatigue behaviors. Features of fracture morphology, such as ratchet mark and fatigue striation, are identifiable to differentiate load types and stress levels. Both bending and torsion may play important roles in fatigue fractures of the coil. The study proposes an effective approach to study load-specific fatigue characteristics of medical coils which provides fundamental knowledge for medical lead design and clinical fracture diagnosis.

Deep Brain Stimulation-Related Surgical Site Infections: A Systematic Review and Meta-Analysis

BACKGROUND

Over the last decades, the increased use of deep brain stimulation (DBS) has raised concerns about the potential adverse health effects of the treatment. Surgical site infections (SSIs) following an elective surgery remain a major challenge for neurosurgeons. Few studies have examined the prevalence and risk factors of DBS-related complications, particularly focusing on SSIs.

OBJECTIVES

We systematically searched published literature, up to June 2020, with no language restrictions.

MATERIALS AND METHODS

Eligible were studies that examined the prevalence of DBS-related SSIs, as well as studies that examined risk and preventive factors in relation to SSIs. We extracted information on study characteristics, follow-up, exposure and outcome assessment, effect estimate and sample size. Summary odds ratios (sOR) and 95% confidence intervals (CI) were calculated from random-effects meta-analyses; heterogeneity and small-study effects were also assessed.

RESULTS

We identified 66 eligible studies that included 12,258 participants from 27 countries. The summary prevalence of SSIs was estimated at 5.0% (95% CI: 4.0%-6.0%) with higher rates for dystonia (6.5%), as well as for newer indications of DBS, such as epilepsy (9.5%), Tourette syndrome (5.9%) and OCD (4.5%). Similar prevalence rates were found between early-onset and late-onset hardware infections. Among risk and preventive factors, the perioperative implementation of intra-wound vancomycin was associated with statistically significantly lower risk of SSIs (sOR: 0.26, 95% CI: 0.09-0.74). Heterogeneity was nonsignificant in most meta-analyses.

CONCLUSION

The present study confirms the still high prevalence of SSIs, especially for newer indications of DBS and provides evidence that preventive measures, such as the implementation of topical vancomycin, seem promising in reducing the risk of DBS-related SSIs. Large clinical trials are needed to confirm the efficacy and safety of such measures.

Brain Atrophy Following Deep Brain Stimulation: Management of a Moving Target

Clinical vignette:

A 51-year-old man with essential tremor (ET) had bilateral ventralis intermedius nucleus deep brain stimulation (VIM-DBS) placed to address refractory tremor. Despite well-placed DBS leads and adequate tremor response, he subsequently experienced worsening. Re-programming of the device and reconfirming the electrical thresholds for benefits and side effects were both performed. Six years following DBS implantation, repeat imaging revealed brain atrophy and a measured lead position change with a coincident change in clinical response.

Clinical dilemma:

What do we know about brain atrophy affecting lead placement and long-term DBS effectiveness? What are the potential strategies to combat narrowed therapeutic thresholds and to maximize DBS therapeutic benefit?

Clinical solution:

Decreasing the electrical field of stimulation and programming in a bipolar configuration are strategies to provide symptomatic tremor control and to minimize stimulation-induced side effects.

Gaps in knowledge:

Currently, effects of brain atrophy, and factors underpinning emergence of side effects and/or loss of benefit in chronic VIM-DBS remain largely unexplored.

Risk Factors for Wire Fracture or Tethering in Deep Brain Stimulation: A 15-Year Experience

BACKGROUND

In deep brain stimulation (DBS), tunneled lead and extension wires connect the implantable pulse generator to the subcortical electrode, but circuit discontinuity and wire revision compromise a significant portion of treatments.

OBJECTIVE

To identify factors predisposing to fracture or tethering of the lead or extension wire in patients undergoing DBS.

METHOD

Retrospective review of wire-related complications was performed in a consecutive series of patients treated with DBS at a tertiary academic medical center over 15 yr.

RESULTS

A total of 275 patients had 513 extension wires implanted or revised. There were 258 extensions of 40 cm implanted with a postauricular connector (50.3%), 229 extensions of 60 cm with a parietal connector (44.6%), and 26 extensions 40 cm with a parietal connector (5.1%). In total, 26 lead or extension wires (5.1%) were replaced for fracture. Fracture rates for 60 cm extensions with a parietal connector, 40 cm wires with a postauricular connector, and 40 cm extensions with a parietal connector were 0.2, 1.4, and 12.9 fractures per 100 wire-years, significantly different on log-rank test. Total 16 (89%) 40 cm extension wires with a postauricular connector had fracture implicating the lead wire. Tethering occurred only in patients with 60 cm extensions with parietal connectors (1.14 tetherings per 100 wire-years). Reoperation rate correlated with younger age, dystonia, and target in the GPI.

CONCLUSION

The 40 cm extensions with parietal connectors have the highest fracture risk and should be avoided. Postauricular connectors risk lead wire fracture and should be employed cautiously. The 60 cm parietal wires may reduce fracture risk but increase tethering risk.

Surgical management of adverse events associated with deep brain stimulation: A single-center experience

Objectives:

Deep brain stimulation is widely used to treat movement disorders and selected neuropsychiatric disorders. Despite the fact, the surgical methods vary among centers. In this study, we aimed to evaluate our own surgical complications and how we performed surgical troubleshooting.

Methods:

A retrospective chart review was performed to evaluate the clinical data of patients who underwent deep brain stimulation surgery and deep brain stimulation–related procedures at our center between October 2014 and September 2019. We reviewed surgical complications and how surgical troubleshooting was performed, regardless of where the patient underwent the initial surgery.

Results:

A total of 92 deep brain stimulation lead implantation and 43 implantable pulse generator replacement procedures were performed. Among the 92 lead implantation procedures, there were two intracranial lead replacement surgeries and one deep brain stimulation lead implantation into the globus pallidus to add to existing deep brain stimulation leads in the bilateral subthalamic nuclei. Wound revision for superficial infection of the implantable pulse generator site was performed in four patients. There was neither intracerebral hemorrhage nor severe hardware infection in our series of procedures. An adaptor (extension cable) replacement was performed due to lead fracture resulting from a head trauma in two cases.

Conclusion:

We report our experience of surgical management of adverse events associated with deep brain stimulation therapy with clinical vignettes. Deep brain stimulation surgery is a safe and effective procedure when performed by a trained neurosurgeon. It is important for clinicians to be aware that there are troubles that are potentially manageable with optimal surgical treatment.

Post-placement Lead Deformation Secondary to Cerebrospinal Fluid Loss in Transventricular Trajectory During Responsive Neurostimulation Surgery

Responsive nerve stimulation (RNS) represents a safe and effective treatment option for patients with medically refractory temporal lobe epilepsy. In cases of long intraparenchymal course and posterior-anterior electrode direction through occipital burr holes, disciplined stereotaxy is essential for stimulation of the appropriate target.

A 13-year-old female with a history of multifocal, independent, bitemporal-onset seizures since 12 months of age showing evidence of left-sided mesial temporal sclerosis on MRI, underwent placement of bilateral mesial temporal RNS leads. An O-arm spin was performed after the placement and the images obtained were fused to the preoperative CT images. It demonstrated curvature of the leads, with some deviation from the planned trajectory, but no deviation from the target, that was worse on the left side, compared to the right; the left lead was placed first, followed by the right lead. Following discussion with our epilepsy neurology colleagues in the operating room, electrophysiological measurements from the implanted leads showed cleared epileptic activity and therefore no repositioning was pursued. Our hypothesis at that time was that cerebrospinal fluid leakage distorted the underlying ventricular anatomy causing some curvature in the lead during transventricular course and prolonged consideration during surgery.

In conclusion, transventricular trajectories during RNS lead placement may lead to cerebrospinal fluid loss and associated lead deformation. The distal aspect of the lead may nonetheless reside in the desired surgical target. Neuromonitoring for epileptic signature can provide reassurance with regard to accurate lead placement, obviating the need for lead repositioning. Surgeons should also recognize that fused imaging may confuse inferred anatomic position from preoperative MRI with actual anatomy post brain shift.

Emerging technologies for improved deep brain stimulation

Deep brain stimulation (DBS) is an effective treatment for common movement disorders and has been used to modulate neural activity through delivery of electrical stimulation to key brain structures. The long-term efficacy of stimulation in treating disorders, such as Parkinson's disease and essential tremor, has encouraged its application to a wide range of neurological and psychiatric conditions. Nevertheless, adoption of DBS remains limited, even in Parkinson's disease. Recent failed clinical trials of DBS in major depression, and modest treatment outcomes in dementia and epilepsy, are spurring further development. These improvements focus on interaction with disease circuits through complementary, spatially and temporally specific approaches. Spatial specificity is promoted by the use of segmented electrodes and field steering, and temporal specificity involves the delivery of patterned stimulation, mostly controlled through disease-related feedback. Underpinning these developments are new insights into brain structure-function relationships and aberrant circuit dynamics, including new methods with which to assess and refine the clinical effects of stimulation.

Functional MRI Safety and Artifacts during Deep Brain Stimulation: Experience in 102 Patients

BackgroundWith growing numbers of patients receiving deep brain stimulation (DBS), radiologists are encountering these neuromodulation devices at an increasing rate. Current MRI safety guidelines, however, limit MRI access in these patients.PurposeTo describe an MRI (1.5 T and 3 T) experience and safety profile in a large cohort of participants with active DBS systems and characterize the hardware-related artifacts on images from functional MRI.Materials and MethodsIn this prospective study, study participants receiving active DBS underwent 1.5- or 3-T MRI (T1-weighted imaging and gradient-recalled echo [GRE]-echo-planar imaging [EPI]) between June 2017 and October 2018. Short- and long-term adverse events were tracked. The authors quantified DBS hardware-related artifacts on images from GRE-EPI (functional MRI) at the cranial coil wire and electrode contacts. Segmented artifacts were then transformed into standard space to define the brain areas affected by signal loss. Two-sample t tests were used to assess the difference in artifact size between 1.5- and 3-T MRI.ResultsA total of 102 participants (mean age ± standard deviation, 60 years ± 11; 65 men) were evaluated. No MRI-related short- and long-term adverse events or acute changes were observed. DBS artifacts were most prominent near the electrode contacts and over the frontoparietal cortical area where the redundancy of the extension wire is placed subcutaneously. The mean electrode contact artifact diameter was 9.3 mm ± 1.6, and 1.9% ± 0.8 of the brain was obscured by the coil artifact. The coil artifacts were larger at 3 T than at 1.5 T, obscuring 2.1% ± 0.7 and 1.4% ± 0.7 of intracranial volume, respectively (P < .001). The superficial frontoparietal cortex and deep structures neighboring the electrode contacts were most commonly obscured.ConclusionWith a priori local safety testing, patients receiving deep brain stimulation may safely undergo 1.5- and 3-T MRI. Deep brain stimulation hardware-related artifacts only affect a small proportion of the brain.© RSNA, 2019Online supplemental material is available for this article.See also the editorial by Martin in this issue.

Single-Center Complication Analysis Associated with Surgical Replacement of Implantable Pulse Generators in Deep Brain Stimulation

BACKGROUND/AIMS

Internal pulse generator (IPG) replacement is considered a relatively minor surgery but exposes the deep brain stimulation system to the risk of infectious and mechanical adverse events. We retrospectively reviewed complications associated with IPG replacement surgery in our center and reviewed the most relevant publications on the issue.

METHODS

A retrospective analysis of all the IPG replacements performed in our center from January 2003 until March 2018 was performed. A logistic regression model was used to analyze the risk factors associated with IPG infections at our center.

RESULTS

A total of 171 IPG replacements in 93 patients were analyzed. The overall rate of replacement complications was 8.8%, whereas the rate of infection was 5.8%. IPG removal was required in 8 out of 10 infected cases. An increased risk of infection was found in patients with subcutaneous thoracic placement of the IPG (OR 5.3, p = 0.016). The most commonly isolated germ was Staphylococcus coagulase negative (60%). We found a non-significant trend towards increased risk of infection in patients with more than 3 replacements (p = 0.07).

CONCLUSIONS

Infection is the most frequent complication related to IPG replacement. Staphylococcus coagulase negative is the most commonly isolated bacteria causing the infection. According to our results, the subcutaneous thoracic placement represents a greater risk of infection compared to subcutaneous abdominal placement.

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.

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.

Deep brain stimulation hardware-related infections: 10-year experience at a single institution

OBJECTIVE

Deep brain stimulation is an effective surgical treatment for managing some neurological and psychiatric disorders. Infection related to the deep brain stimulator (DBS) hardware causes significant morbidity: hardware explantation may be required; initial disease symptoms such as tremor, rigidity, and bradykinesia may recur; and the medication requirements for adequate disease management may increase. These morbidities are of particular concern given that published DBS-related infection rates have been as high as 23%. To date, however, the key risk factors for and the potential preventive measures against these infections remain largely uncharacterized. In this study, the authors endeavored to identify possible risk factors for DBS-related infection and analyze the efficacy of prophylactic intrawound vancomycin powder (VP).

METHODS

The authors performed a retrospective cohort study of patients who had undergone primary DBS implantation at a single institution in the period from December 2005 through September 2015 to identify possible risk factors for surgical site infection (SSI) and to assess the impact of perioperative (before, during, and after surgery) prophylactic antibiotics on the SSI rate. They also evaluated the effect of a change in the National Healthcare Safety Network's definition of SSI on the number of infections detected. Statistical analyses were performed using the 2-sample t-test, the Wilcoxon rank-sum test, the chi-square test, Fisher's exact test, or logistic regression, as appropriate for the variables examined.

RESULTS

Four hundred sixty-four electrodes were placed in 242 adults during 245 primary procedures over approximately 10.5 years; most patients underwent bilateral electrode implantation. Among the 245 procedures, 9 SSIs (3.7%) occurred within 90 days and 16 (6.5%) occurred within 1 year of DBS placement. Gram-positive bacteria were the most common etiological agents. Most patient- and procedure-related characteristics did not differ between those who had acquired an SSI and those who had not. The rate of SSIs among patients who had received intrawound VP was only 3.3% compared with 9.7% among those who had not received topical VP (OR 0.32, 95% CI 0.10-1.02, p = 0.04). After controlling for patient sex, the association between VP and decreased SSI risk did not reach the predetermined level of significance (adjusted OR 0.32, 95% CI 0.10-1.03, p = 0.06). The SSI rates were similar after staged and unstaged implantations.

CONCLUSIONS

While most patient-related and procedure-related factors assessed in this study were not associated with the risk for an SSI, the data did suggest that intrawound VP may help to reduce the SSI risk after DBS implantation. Furthermore, given the implications of SSI after DBS surgery and the frequency of infections occurring more than 90 days after implantation, continued follow-up for at least 1 year after such a procedure is prudent to establish the true burden of these infections and to properly treat them when they do occur.

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.

Deep Brain Stimulation in Moroccan Patients With Parkinson's Disease: The Experience of Neurology Department of Rabat

Introduction: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is known as a therapy of choice of advanced Parkinson's disease. The present study aimed to assess the beneficial and side effects of STN DBS in Moroccan Parkinsonian patients. Material and Methods: Thirty five patients underwent bilateral STN DBS from 2008 to 2016 in the Rabat University Hospital. Patients were assessed preoperatively and followed up for 6 to 12 months using the Unified Parkinson's Disease Rating Scale in four conditions (stimulation OFF and ON and medication OFF and ON), the levodopa-equivalent daily dose (LEDD), dyskinesia and fluctuation scores and PDQ39 scale for quality of life (QOL). Postoperative side effects were also recorded. Results: The mean age at disease onset was 42.31 ± 7.29 years [28-58] and the mean age at surgery was 54.66 ± 8.51 years [34-70]. The median disease duration was 11.95 ± 4.28 years [5-22]. Sixty-three percentage of patients were male. 11.4% of patients were tremor dominant while 45.71 showed akinetic-rigid form and 42.90 were classified as mixed phenotype. The LEDD before surgery was 1200 mg/day [800-1500]. All patients had motor fluctuations whereas non-motor fluctuations were present in 61.80% of cases. STN DBS decreased the LEDD by 51.72%, as the mean LEDD post-surgery was 450 [188-800]. The UPDRS-III was improved by 52.27%, dyskinesia score by 66.70% and motor fluctuations by 50%, whereas QOL improved by 27.12%. Post-operative side effects were hypophonia (2 cases), infection (3 cases), and pneumocephalus (2 cases). Conclusion: Our results showed that STN DBS is an effective treatment in Moroccan Parkinsonian patients leading to a major improvement of the most disabling symptoms (dyskinesia, motor fluctuation) and a better QOL.