Diagnosis and treatment of complications related to deep brain stimulation hardware

A Review on Implantable Neuroelectrodes

The efficacy of every neuromodulation modality depends upon the characteristics of the electrodes used to stimulate the chosen target. The geometrical, chemical, mechanical and physical configuration of electrodes used in neurostimulation affects several performance attributes like stimulation efficiency, selectivity, tissue response, etc. The efficiency of stimulation in relation to electrode impedance is influenced by the electrode material and/or its geometry. The nature of the electrode material determines the charge transfer across the electrode-tissue interface, which also relates to neuronal tissue damage. Electrode morphology or configuration pattern can facilitate the modulation of extracellular electric field (field shaping). This enables selective activation of neurons and minimizes side effects. Biocompatibility and biostability of the electrode materials or electrode coating have a role in glial formation and tissue damage. Mechanical and electrochemical stability (corrosion resistance) determines the long-term efficacy of any neuromodulation technique. Here, a review of electrodes typically used for implantable neuromodulation is discussed. Factors affecting the performance of electrodes like stimulation efficiency, selectivity and tissue responses to the electrode-tissue interface are discussed. Technological advancements to improve electrode characteristics are also included.

Deep Brain Stimulation for the Management of Refractory Neurological Disorders: A Comprehensive Review

In recent decades, deep brain stimulation (DBS) has been extensively studied due to its reversibility and significantly fewer side effects. DBS is mainly a symptomatic therapy, but the stimulation of subcortical areas by DBS is believed to affect the cytoarchitecture of the brain, leading to adaptability and neurogenesis. The neurological disorders most commonly studied with DBS were Parkinson's disease, essential tremor, obsessive-compulsive disorder, and major depressive disorder. The most precise approach to evaluating the location of the leads still relies on the stimulus-induced side effects reported by the patients. Moreover, the adequate voltage and DBS current field could correlate with the patient's symptoms. Implantable pulse generators are the main parts of the DBS, and their main characteristics, such as rechargeable capability, magnetic resonance imaging (MRI) safety, and device size, should always be discussed with patients. The safety of MRI will depend on several parameters: the part of the body where the device is implanted, the part of the body scanned, and the MRI-tesla magnetic field. It is worth mentioning that drug-resistant individuals may have different pathophysiological explanations for their resistance to medications, which could affect the efficacy of DBS therapy. Therefore, this could explain the significant difference in the outcomes of studies with DBS in individuals with drug-resistant neurological conditions.

Investigation of a Deep Brain Stimulator (DBS) System

A deep brain stimulator (DBS) device is a surgically implanted system that delivers electrical impulses to specific targets in the brain to treat abnormal movement disorders. A DBS is like a cardiac pacemaker, but instead of sending electrical signals to the heart, it sends them to the brain instead. When DBS leads and extension wires are exposed in the biological environment, this can adversely affect impedance and battery life, resulting in poor clinical outcomes. A posthumously extracted DBS device was evaluated using visual inspection and optical microscopy as well as electrical and mechanical tests to quantify the damage leading to its impairment. The implantable pulse generator (IPG) leads, a component of the DBS, contained cracks, delamination, exfoliations, and breakage. Some aspects of in vivo damage were observed in localized areas discussed in this paper. The duration of the time in months that the DBS was in vivo was estimated based on multiple regression analyses of mechanical property testing from prior research of pacemaker extensions. The test results of three DBS extensions, when applied to the regressions, were used to estimate the in vivo duration in months. This estimation approach may provide insight into how long the leads can function effectively before experiencing mechanical failure. Measurements of the extension coils demonstrated distortion and stretching, demonstrating the changes that may occur in vivo. These changes can alter the impedance and potentially reduce the effectiveness of the clinical treatment provided by the DBS system. Ultimately, as both DBSs and pacemakers use the same insulation and lead materials, the focus of this paper is to develop a proof of concept demonstrating that the mechanical properties measured from pacemaker extensions and leads extracted posthumously of known duration, measured in months while in vivo, can be used to predict the duration of DBS leads of unknown lifespan. The goal is to explore the validity of the proposed model using multiple regression of mechanical properties.

Efficacy of Occipital Nerve Stimulation in Trigeminal Autonomic Cephalalgias: A Systematic Review

BACKGROUND

Trigeminal autonomic cephalalgias (TACs) are a group of highly disabling primary headache disorders. Although pharmacological treatments exist, they are not always effective or well tolerated. Occipital nerve stimulation (ONS) is a potentially effective surgical treatment.

OBJECTIVE

To perform a systematic review of the efficacy of ONS in treating TACs.

METHODS

A systematic review was performed using Medline, Embase, and Cochrane databases. Primary outcomes were reduction in headache intensity, duration, and frequency. Secondary outcomes included adverse event rate and reduction in medication use. Because of large differences in outcome measures, data for patients suffering from short-lasting, unilateral, and neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) and cranial autonomic symptoms (SUNA) were reported separately. Risk of bias was assessed using the NIH Quality Assessment Tools.

RESULTS

A total of 417 patients from 14 published papers were included in the analysis, of which 15 patients were in the SUNCT/SUNA cohort. The mean reduction in headache intensity and duration was 26.2% and 31.4%, respectively. There was a mean reduction in headache frequency of 50%, as well as a 61.2% reduction in the use of abortive medications and a 31.1% reduction in the use of prophylactic medications. In the SUNCT/SUNA cohort, the mean decrease in headache intensity and duration was 56.8% and 42.8%. The overall responder rate, defined as a >50% reduction in attack frequency, was 60.8% for the non-SUNCT/non-SUNA cohort and 66.7% for the SUNCT/SUNA cohort. Adverse events requiring repeat surgery were reported in 33% of cases. Risk of bias assessment suggests that articles included in this review had reasonable internal validity.

CONCLUSION

ONS may be an effective surgical treatment for approximately two thirds of patients with medically refractory TACs.

Low-intensity focused ultrasound targeting the nucleus accumbens as a potential treatment for substance use disorder: safety and feasibility clinical trial

Introduction

While current treatments for substance use disorder (SUD) are beneficial, success rates remain low and treatment outcomes are complicated by co-occurring SUDs, many of which are without available medication treatments. Research involving neuromodulation for SUD has recently gained momentum. This study evaluated two doses (60 and 90 W) of Low Intensity Focused Ultrasound (LIFU), targeting the bilateral nucleus accumbens (NAc), in individuals with SUD.

Methods

Four participants (three male), who were receiving comprehensive outpatient treatment for opioid use disorder at the time of enrollment and who also had a history of excessive non-opioid substance use, completed this pilot study. After confirming eligibility, these participants received 10 min sham LIFU followed by 20 min active LIFU (10 min to left then right NAc). Outcomes were the safety, tolerability, and feasibility during the LIFU procedure and throughout the 90-day follow-up. Outcomes also included the impact of LIFU on cue-induced substance craving, assessed via Visual Analog Scale (VAS), both acutely (pre-, during and post-procedure) and during the 90-day follow-up. Daily craving ratings (without cues) were also obtained for one-week prior to and one-week following LIFU.

Results

Both LIFU doses were safe and well-tolerated based on reported adverse events and MRI scans revealed no structural changes (0 min, 24 h, and 1-week post-procedure). For the two participants receiving "enhanced" (90 W) LIFU, VAS craving ratings revealed active LIFU attenuated craving for participants' primary substances of choice relative to sham sonication. For these participants, reductions were also noted in daily VAS craving ratings (0 = no craving; 10 = most craving ever) across the week following LIFU relative to pre-LIFU; Participant #3 pre- vs. post-LIFU: opioids (3.6 ± 0.6 vs. 1.9 ± 0.4), heroin (4.2 ± 0.8 vs. 1.9 ± 0.4), methamphetamine (3.2 ± 0.4 vs. 0.0 ± 0.0), cocaine (2.4 ± 0.6 vs. 0.0 ± 0.0), benzodiazepines (2.8 ± 0.5 vs. 0.0 ± 0.0), alcohol (6.0 ± 0.7 vs. 2.7 ± 0.8), and nicotine (5.6 ± 1.5 vs. 3.1 ± 0.7); Participant #4: alcohol (3.5 ± 1.3 vs. 0.0 ± 0.0) and nicotine (5.0 ± 1.8 vs. 1.2 ± 0.8) (all p's < 0.05). Furthermore, relative to screening, longitudinal reductions in cue-induced craving for several substances persisted during the 90-day post-LIFU follow-up evaluation for all participants.

Discussion

In conclusion, LIFU targeting the NAc was safe and acutely reduced substance craving during the LIFU procedure, and potentially had longer-term impact on craving reductions. While early observations are promising, NAc LIFU requires further investigation in a controlled trial to assess the impact on substance craving and ultimately substance use and relapse.

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

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

Use of a Pericranial Flap Technique for Deep Brain Stimulation Hardware Protection and Improved Cosmesis

OBJECTIVES

Deep brain stimulation (DBS) has become an established neuromodulation therapy; however, surgical site complications such as hardware skin erosion remain an important risk and can predispose to infection, requiring explantation of the system. Nuances of surgical technique can affect wound healing, cosmetic outcome, comfort, and risk of infection. In this study, we describe our experience with a layered closure technique using a vascularized pericranial flap for improving cosmesis and protection of the implanted hardware against skin erosion and infection.

MATERIALS AND METHODS

We retrospectively reviewed 636 individuals (746 lead implantations) who underwent DBS surgery by a single academic neurosurgeon between 2001 and 2020. A layered pericranial flap closure technique for the burr-hole and connector sites was instituted in 2015. We assessed the effects of a multimodal infection prevention approach that included the pericranial flap on hardware complication rates compared with the premultimodality cohort, and we report the nuances of the technique.

RESULTS

In our institutional experience, we found that implementation of a pericranial flap closure technique can enhance the subjective cosmetic result at the burr-hole cover site and increase patient comfort and satisfaction. In addition, we found a decrease in hardware infection rates in the current cohort with a multimodal infection prevention regimen that includes the pericranial-flap technique (n = 256, 2015-2020 period) to 1.2% (p = 0.006), from 6.9% in the earlier cohort (n = 490, 2001-2015 period).

CONCLUSIONS

The report highlights the potential of a pericranial-flap closure technique as a surgical adjunct to improve DBS surgical site healing and cosmesis and may, as part of a multimodal strategy, contribute to decreased risk of skin breakdown and hardware infection.

Transcranial Focused Ultrasound Stimulation of Periaqueductal Gray for Analgesia

OBJECTIVE

Transcranial focused ultrasound (tFUS) is regarded as a promising non-invasive stimulation tool for modulating brain circuits. The aim of this study is to explore the feasibility of tFUS stimulation for analgesia application.

METHODS

50 l of 3% formalin solution was injected into the rats left hindpaw to build a pain model, and then the local field potential (LFP) activities of the dorsal horn were tracked after a recording electrode was placed in the spinal cord. Rats were randomly divided into two groups: control group and tFUS group. At the 30th minute after formalin injection, tFUS (US-650 kHz, PD = 1 ms, PRF = 100 Hz, 691 mW/cm2) was conducted to stimulate the periaqueductal gray (PAG) for 5 minutes (on 5 s and off 5 s) in tFUS group, but there was no treatment in control group. In addition, the analgesia mechanism (LFP recording from the PAG) and safety assessment (histology analysis) were carried out.

RESULTS

The tFUS stimulation of the PAG can suppress effectively the nociceptive activity generated by formalin. The findings of the underlying mechanism exploration indicated that the tFUS stimulation was able to activate the PAG directly without causing significant temperature change and tissue injury.

CONCLUSION

The results illustrated that the tFUS stimulation of the PAG can achieve the effect of analgesia.

SIGNIFICANCE

This work provides new insights for the development of non-invasive analgesic technology in the future.

A systematic review of Twiddler's syndrome: a hardware-related complication of deep brain stimulation

Twiddler's syndrome (TS) is a hardware-related complication of deep brain stimulation which has not been well documented and is probably underreported. The objective of this study is to comprehensively describe TS by systematically reviewing the related literature. The methods include selecting the eligible studies based on the inclusion and exclusion criteria. Data about studies and TS were collected. A descriptive statistical analysis of the extracted data was performed. We found 18 eligible studies describing 23 patients with TS. The mean age of the 23 patients was 61.4 ± 15.9 years (range, 16-79 years.). The percentage of TS in the female population was 91.3% (females: 21/23). The incidence of postoperative TS was 1.4% (6 out of 437) per patient and 1.1% (8 out of 709) per extension wire. The mean time to clinical presentation was 9.9 ± 10.3 months (range, 0.5-36 months). Nineteen of the twenty-three patients presented with a rebound of previous symptoms. Twelve of the twenty-three patients had high impedance at the postoperative checkup of the DBS system. A plain X-ray indicated twisted extension wires in almost all these patients. All patients meeting the definition of postoperative device-related TS underwent revision surgery. TS is more prevalent in females. Based on the typical clinical symptoms (rebound of the previous symptoms, high impedance, and X-ray demonstration), the differential diagnosis can often be straightforward. TS should thus be taken into consideration when attempting to explain or rule out hardware malfunction. The timely recognition and proper revision of TS can prevent further serious damage.

Is It Possible to Save the Deep Brain Stimulation Hardware when Presenting with Wound Dehiscence or Hardware Infection?

INTRODUCTION

Deep brain stimulation (DBS) hardware complications have been traditionally managed by removal of the entire system. Explantation of the system results in prolonged interruption to the patient's care and potential challenges when considering reimplantation of the cranial leads. The purpose of this study was to understand whether complete explantation can be avoided for patients initially presenting with wound dehiscence and/or infection of hardware.

METHODS

We performed a retrospective study that included 30 cases of wound dehiscence or infection involving the DBS system. Patients underwent reoperation without explantation of the DBS system, with partial explanation, or with complete explantation as initial management of the complication.

RESULTS

A total of 17/30 cases were managed with hardware-sparing wound revisions. The majority presented with wound dehiscence (94%), with the scalp (n = 9) as the most common location. This was successful in 76.5% of patients (n = 13). Over 11/30 patients were managed with partial explantation. The complication was located at the generator (91%) or at the scalp (9%). Partial explantation was successful in 64% of patients (n = 7). In cases that underwent a lead-sparing approach, 33% of patients ultimately required removal of the intracranial lead, and 2/30 cases of hardware infection were managed initially with total explantation.

DISCUSSION/CONCLUSION

Wound dehiscence can be successfully managed without complete removal of the DBS system in most cases. In cases of infection, removing the involved component(s) and sparing the intracranial leads may be considered. Wound revision without removal of the entire DBS system is safe and can improve quality of life by preventing or shortening the withdrawal of DBS treatment.

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.

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 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.

Brain Metabolic Changes with Longitudinal Transcutaneous Afferent Patterned Stimulation in Essential Tremor Subjects

Background

Non-invasive peripheral nerve stimulation, also referred to as transcutaneous afferent patterned stimulation (TAPS), reduces hand tremor in essential tremor (ET) subjects. However, the mechanism of action of TAPS is unknown. Here, we investigated changes in brain metabolism over three months of TAPS use in ET subjects.

Methods

This was an interventional, open label, single group study enrolling 5 ET subjects. They received 40 minutes of TAPS treatment twice daily for 90 days. Brain metabolic activity and tremor severity were measured using 18F-fluorodeoxyglucose (FDG) PET/CT, and the Tremor Research Group Essential Tremor Rating Assessment Scale (TETRAS), respectively, at baseline and after 90 days. Tremor power and frequency was measured before and after all TAPS sessions using an onboard three-axis accelerometer.

Results

FDG PET/CT revealed areas of hypermetabolism in ipsilateral cerebellar hemisphere and hypometabolism in contralateral cerebellar hemisphere following 90 days of TAPS treatment, compared to day one (uncorrected p value <0.05). Paired pre-post kinematic measurements over 90 days showed significantly decreased tremor power (p < 0.0001) but no change in tremor frequency. The TETRAS score on day 1 decreased from 6.5 ± 2.5 to 4.1 ± 1.8 following TAPS (p = 0.05). The pre-post TETRAS scores on day 90: 4.9 ± 1.5 and 4.1± 1 were lower than pre-TAPS TETRAS score on day 1 (p = 0.14 and 0.05, respectively).

Conclusions

Our results suggest that longitudinal TAPS of the median and radial nerves modulates brain metabolism in areas instrumental to motor coordination and implicated in ET. Clinically, TAPS reduced tremor power, but had no effect on tremor frequency. This study paves the way for comprehensive studies in larger cohorts to further elucidate the mechanism of TAPS.

Highlights

Non-invasive peripheral nerve stimulation, also referred to as transcutaneous afferent patterned stimulation (TAPS), reduces hand tremor in essential tremor subjects. Longitudinal TAPS therapy alters cerebellar metabolism, which can be a cause or consequence of tremor reduction. Cerebellar-premotor region connectivity may play a role in the anti-tremor effects of TAPS.

Parkinson's disease and skin

Parkinson's disease is associated with a variety of dermatologic disorders and the study of skin may provide insights into pathophysiological mechanisms underlying this common neurodegenerative disorder. Skin disorders in patients with Parkinson's disease can be divided into two major groups: 1) non-iatrogenic disorders, including melanoma, seborrheic dermatitis, sweating disorders, bullous pemphigoid, and rosacea, and 2) iatrogenic disorders related either to systemic side effects of antiparkinsonian medications or to the delivery system of antiparkinsonian therapy, including primarily carbidopa/levodopa, rotigotine and other dopamine agonists, amantadine, catechol-O-methyl transferase inhibitors, subcutaneous apomorphine, levodopa/carbidopa intestinal gel, and deep brain stimulation. Recent advances in our understanding of the role of α-synuclein in peripheral tissues, including the skin, and research based on induced pluripotent stem cells derived from skin fibroblasts have made skin an important target for the study of Parkinson's disease pathogenesis, drug discovery, novel stem cell therapies, and diagnostics.

Emergencies and critical issues in Parkinson's disease

Complications from Parkinson’s disease may develop over the disease course, sometimes unexpectedly, and require prompt or even urgent medical intervention. The most common are associated with aggravation of motor symptoms; serious non-motor complications, such as psychosis, orthostatic hypotension or sleep attacks, also occur. Here we review such complications, their clinical presentation, precipitating factors and management, including those related to using device-aided therapies. Early recognition and prompt attention to these critical situations is challenging, even for the Parkinson’s disease specialist, but is essential to prevent serious problems.

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.

Update on current and emerging therapies for dystonia

Treatment strategies for dystonia depend on the focal, segmental or generalized distribution of symptoms. Chemodenervation with botulinum toxin remains the treatment of choice for focal- or select-body regions in generalized and segmental dystonia. A potentially longer acting formulation of botulinum toxin is being investigated besides the currently available formulations. Electromyography increases toxin injection accuracy and may reduce injection number, frequency, side effects and costs by identifying dystonic muscle activity. Oral anticholinergics, baclofen and clonazepam are used off-label, but novel drugs in development include sodium oxybate, zonisamide and perampanel. Characterizing dystonia as a sensorimotor circuit disorder has prompted the use of noninvasive neuromodulation procedures. These techniques need further study but simultaneous rehabilitation techniques appear to also improve outcomes. Pallidal deep-brain stimulation is beneficial for medication-refractory primary generalized and possibly focal dystonia such as cervical dystonia. Certain genetic conditions are amenable to specific therapies and future gene-targeted therapies could benefit selected dystonia patients.

A curious case of DBS radiofrequency programmer interference

Deep brain stimulation (DBS) systems frequently rely on radiofrequency (RF) transmission for patient programming. The potential exists for other devices to interfere with communication between the internal pulse generator (IPG) and the programming device. In this paper, we are reporting a case of programming interference between the IPG and the WaveID device.

Optimization-Based Contact Fault Alleviation in Deep Brain Stimulation Leads

Deep brain stimulation (DBS) is a neurosurgical treatment in, e.g., Parkinson's Disease. Electrical stimulation in DBS is delivered to a certain target through electrodes implanted into the brain. Recent developments aiming at better stimulation target coverage and lesser side effects have led to an increase in the number of contacts in a DBS lead as well as higher hardware complexity. This paper proposes an optimization-based approach to alleviation of the fault impact on the resulting therapeutical effect in field steering DBS. Faulty contacts could be an issue given recent trends of increasing number of contacts in DBS leads. Hence, a fault detection/alleviation scheme, such as the one proposed in this paper, is necessary ensure resilience in the chronic stimulation. Two alternatives are considered and compared with the stimulation prior to the fault: one using higher amplitudes on the remaining contacts and another with alleviating contacts in the neighborhood of the faulty one. Satisfactory compensation for a faulty contact can be achieved in both ways. However, to designate alleviating contacts, a model-based optimization procedure is necessary. Results suggest that stimulating with more contacts yields configurations that are more robust to contact faults, though with reduced selectivity.

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.

Surgical treatment of dystonia

INTRODUCTION

Treatment of dystonia should be individualized and tailored to the specific needs of patients. Surgical treatment is an important option in medically refractory cases. Several issues regarding type of the surgical intervention, targets, and predict factors of benefit are still under debate. Areas covered: To date, several clinical trials have proven the benefit and safety of deep brain stimulation (DBS) for inherited and idiopathic isolated dystonia, whereas there is still insufficient evidence in combined and acquired dystonia. The globus pallidus internus (GPi) is the target with the best evidence, but data on the subthalamic nucleus seems also to be promising. Evidence suggests that younger patients with shorter disease duration experience greater benefit following DBS. Pallidotomy and thalamotomy are currently used in subset of carefully selected patients. The development of MRI-guided focused ultrasound might bring new options to ablation approach in dystonia. Expert commentary: GPi-DBS is effective and safe in isolated dystonia and should not be delayed when symptoms compromise quality of life and functionality. Identifying the best candidates to surgery on acquired and combined dystonias is still necessary. New insights about pathophysiology of dystonia and new technological advances will undoubtedly help to tailor surgery and optimize clinical effects.

Manipulating an internal pulse generator until twiddler's syndrome in a patient treated with deep brain stimulation for obsessive-compulsive disorder

BACKGROUND

Twiddler's syndrome consists of rotation or manipulation of an implantable pulse generator (IPG) in its subcutaneous pocket by a patient, thus causing hardware malfunction.

METHODS

This syndrome is being reported more frequently in patients treated with deep brain stimulation (DBS).

RESULTS

We report the case of a woman who had received bed nucleus of stria terminalis (BNST) electrodes for obsessive-compulsive disorder (OCD) and developed twiddler's syndrome a few months after surgery, causing hardware malfunction due to obsessive manipulation of the IPG.

CONCLUSION

The patient did not have compulsions related to touching objects at admission, thus making it difficult to foresee and prevent TS.

Liquid levodopa-carbidopa in advanced Parkinson's disease with motor complications

While levodopa, carbidopa, ascorbic acid solution (LCAS) therapy has been used in patients with advanced Parkinson's disease (PD) for many years, long-term follow-up data is scarce. The present study aimed to determine the long-term retention rate for LCAS therapy, and to identify the causes of LCAS therapy withdrawal. Our study included a series of 38 patients with PD (14 men and 24 women) who underwent LCAS treatment between 2011 and 2013 to alleviate motor complications that were not satisfactorily controlled by optimized conventional anti-parkinsonian treatment at the Seoul National University Hospital. All patients were admitted to educate them about and initiate LCAS treatment for 2-5days, and were then followed up as outpatients. The mean follow-up duration was 12.8months, and three main reasons for LCAS treatment discontinuation were worsening of wearing-off symptoms (8 patients), persistent dyskinesia (4 patients), and poor drug adherence (4 patients). Fourteen patients (36.8%) maintained the LCAS treatment after 12months, and were categorized as the treatment-retention group. The mean percentage of on time without dyskinesia significantly increased from 33.6±17.6% to 57.0±27.7% after LCAS initiation (p=0.016) in the treatment-retention group. Twelve patients (31.6%) were still receiving LCAS treatment after 30months. LCAS treatment can be a non-device assisted therapeutic option for patients who have no access to advanced therapies such as deep brain stimulation and infusional treatments.

Long-Term Efficacy of Constant Current Deep Brain Stimulation in Essential Tremor

OBJECTIVES

Ventralis intermedius deep brain stimulation is an established intervention for medication-refractory essential tremor. Newer constant current stimulation technology offers theoretical advantage over the traditional constant voltage systems in terms of delivering a more biologically stable therapy. There are no previous reports on the outcomes of constant current deep brain stimulation in the treatment of essential tremor. This study aimed to evaluate the long-term efficacy of ventralis intermedius constant current deep brain stimulation in patients diagnosed with essential tremor.

MATERIALS AND METHODS

Essential tremor patients implanted with constant current deep brain stimulation for a minimum of three years were evaluated. Clinical outcomes were assessed using the Fahn-Tolosa-Marin tremor rating scale at baseline and postoperatively at the time of evaluation. The quality of life in the patients was assessed using the Quality of Life in Essential Tremor questionnaire.

RESULTS

Ten patients were evaluated with a median age at evaluation of 74 years (range 66-79) and a mean follow up time of 49.7 (range 36-78) months since starting stimulation. Constant current ventralis intermedius deep brain stimulation was well tolerated and effective in all patients with a mean score improvement from 50.7 ± 5.9 to 17.4 ± 5.7 (p = 0.0020) in the total Fahn-Tolosa-Marin rating scale score (65.6%). Furthermore, the total combined mean Quality of Life in Essential Tremor score was improved from 56.2 ± 4.9 to 16.8 ± 3.5 (p value = 0.0059) (70.1%).

CONCLUSION

This report shows that long-term constant current ventralis intermedius deep brain stimulation is a safe and effective intervention for essential tremor patients.

Central Thalamic Deep-Brain Stimulation Alters Striatal-Thalamic Connectivity in Cognitive Neural Behavior

Central thalamic deep brain stimulation (CT-DBS) has been proposed as an experimental therapeutic approach to produce consistent sustained regulation of forebrain arousal for several neurological diseases. We investigated local field potentials (LFPs) induced by CT-DBS from the thalamic central lateral nuclei (CL) and the striatum as potential biomarkers for the enhancement of lever-pressing skill learning. LFPs were simultaneously recorded from multiple sites in the CL, ventral striatum (Vstr), and dorsal striatum (Dstr). LFP oscillation power and functional connectivity were assessed and compared between the CT-DBS and sham control groups. The theta and alpha LFP oscillations were significantly increased in the CL and striatum in the CT-DBS group. Furthermore, interhemispheric coherences between bilateral CL and striatum were increased in the theta band. Additionally, enhancement of c-Fos activity, dopamine D2 receptor (Drd2), and α4-nicotinic acetylcholine receptor (α4-nAChR) occurred after CT-DBS treatment in the striatum and hippocampus. CT-DBS strengthened thalamic-striatal functional connectivity, which demonstrates that the inter-regional connectivity enhancement might contribute to synaptic plasticity in the striatum. Altered dopaminergic and cholinergic receptors resulted in modulation of striatal synaptic plasticity's ability to regulate downstream signaling cascades for higher brain functions of lever-pressing skill learning.

The Feasibility of Using Acoustic Markers of Speech for Optimizing Patient Outcomes during Randomized Amplitude Variation in Deep Brain Stimulation: A Proof of Principle Methods Study

Background

Deep brain stimulation (DBS) is an effective treatment for reducing symptoms of tremor. A common and typically subjectively determined adverse effect of DBS is dysarthria. Current assessment protocols are driven by the qualitative judgments of treating clinicians and lack the sensitivity and objectivity required to optimize patient outcomes where multiple stimulation parameters are trialed.

Objective

To examine the effect of DBS on speech in patients receiving stimulation to the posterior sub-thalamic area (PSA) via randomized manipulation of amplitude parameters.

Methods

Six patients diagnosed with tremor receiving treatment via DBS of the PSA were assessed in a double-blinded, within-subjects experimental protocol. Amplitude (i.e., voltage or current) was randomly adjusted across 10 settings, while speech samples (e.g., sustained vowel, counting to 10) were recorded to identify the patient-specific settings required for optimal therapeutic benefit (reduced tremor) with minimal adverse effects (altered speech). Speech production between stimulation parameters was quantified using acoustic analysis.

Results

Speech changed as a response to DBS but those changes were not uniform across patients nor were they generally in line with changes in amplitude with the exception of reduced vocal control and increased mean silence length in two patients. Speech outcomes did not correlate with changes in tremor.

Conclusion

Intra-individual changes in speech were detected as a response to modified amplitude; however, no clear pattern was observed across patients as a group. The use of objective acoustic measures allows for quantification of speech changes during DBS optimization protocols, even when those changes are subtle and potentially difficult to detect perceptually.

Deep brain stimulation for psychiatric diseases: what are the risks?

Despite the application of deep brain stimulation (DBS) as an efficient treatment modality for psychiatric disorders, such as obsessive-compulsive disorder (OCD), Gilles de la Tourette Syndrome (GTS), and treatment refractory major depression (TRD), few patients are operated or included in clinical trials, often for fear of the potential risks of an approach deemed too dangerous. To assess the surgical risks, we conducted an analysis of publications on DBS for psychiatric disorders. A PubMed search was conducted on reports on DBS for OCD, GTS, and TRD. Forty-nine articles were included. Only reports on complications related to DBS were selected and analyzed. Two hundred seventy-two patients with a mean follow-up of 22 months were included in our analysis. Surgical mortality was nil. The overall mortality was 1.1 %: two suicides were unrelated to DBS and one death was reported to be unlikely due to DBS. The majority of complications were transient and related to stimulation. Long-term morbidity occurred in 16.5 % of cases. Three patients had permanent neurological complications due to intracerebral hemorrhage (2.2 %). Complications reported in DBS for psychiatric diseases appear to be similar to those reported for DBS in movement disorders. But class I evidence is lacking. Our analysis was based mainly on small non-randomized studies. A significant number of patients (approximately 150 patients) who were treated with DBS for psychiatric diseases had to be excluded from our analysis as no data on complications was available. The exact prevalence of complications of DBS in psychiatric diseases could not be established. DBS for psychiatric diseases is promising, but remains an experimental technique in need of further evaluation. A close surveillance of patients undergoing DBS for psychiatric diseases is mandatory.

Sudden loss of the deep brain stimulation effect with high impedance without macroscopic fracture: a case report and review of the published literature

The number of deep brain stimulation (DBS) hardware complications has increased during the past decade. In cases of abnormally high lead impedance with no evidence of a macroscopic fracture, optimal treatment options have not yet been established. Here, we present the case of a 49-year-old woman with a 12-year history of Parkinson's disease who received bilateral subthalamic nucleus DBS in March 2006. The patient showed good control of parkinsonism until December 24, 2010, when she awoke with abrupt worsening of parkinsonian symptoms. At telemetric testing, lead impedances were found at >2,000 Ω in all four leads on the left side. Fracture of a lead or an extension wire was suspected. However, radiological screening and palpation revealed no macroscopic fracture. In June 2011, the implantable pulse generator (IPG) was changed under local anesthesia without any complications. Postoperatively, her parkinsonism immediately improved to the previous level, and the lead impedance readings by telemetry were also normalized. The disconnection of the neurostimulator connector block and the hybrid circuit board of the IPG was confirmed by destructive analysis. The present report illustrates that a staged approach that starts with simple IPG replacement can be an option for some cases of acute DBS effect loss with high impedance, when radiological findings are normal, thereby sparing the intact electrodes and extension wires.

Deep brain stimulation

Deep brain stimulation (DBS) has provided remarkable therapeutic benefits for people with a variety of neurological disorders. Despite the uncertainty of the precise mechanisms underlying its efficacy, DBS is clinically effective in improving motor function of essential tremor, Parkinson's disease and primary dystonia and in relieving obsessive-compulsive disorder. Recently, this surgical technique has continued to expand to other numerous neurological diseases with encouraging results. This review highlighted the current and potential future clinical applications of DBS.

Surgical adverse events of deep brain stimulation in the subthalamic nucleus of patients with Parkinson's disease. The learning curve and the pitfalls

BACKGROUND

Several surgical adverse events (SAEs) have been associated with Deep Brain Stimulation (DBS) of the subthalamic nucleus (STN) in Parkinson's Disease (PD) patients, leading to certain confusion about the risk/benefit ratio of this technique, and giving rise to the need of more and more extensive control studies over longer periods. The aim of this article is to identify and quantify the factors associated with the most frequent AEs from STN DBS in PD-diagnosed patients.

METHODS

The following variables were studied: aborted procedure, misplaced leads, intracranial haemorrhage, and seizures. This study was carried out in 233 patients diagnosed with PD, with 455 STN electrodes implanted and follow-up after 7 (8-14) years follow up.

RESULTS

A total amount of 56 SAEs occurred in 49 patients (11.76 % of total procedures, 12.31 % of implanted leads, 21.03 % of patients). SAEs were: five aborted procedures, 26 misplaced leads, ten intracranial haemorrhages, and 15 seizures. Of all the SAEs, long-term effects only happened in two cases of hemiparesis caused by intracranial haemorrhage; the other SAEs were reversible and didn't leave any long-term clinical consequences (0.42 % of procedures, 0.44 % of leads, and 0.86 % of patients).

CONCLUSIONS

STN DBS in PD patients is a safe surgical procedure, with good risk/benefit ratios: procedure reliability/correct lead implantation in 95.59 %, 0 mortality/implanted lead, 0.12 morbidity/implanted lead, and 0.0043 neurological sequelae/implanted lead.

The safety and efficacy of thalamic deep brain stimulation in essential tremor: 10 years and beyond

BACKGROUND

Deep brain stimulation (DBS) has proven to be a safe and effective therapy for refractory essential tremor, but information regarding long-term outcomes is lacking.

OBJECTIVES

We aimed to assess the long-term safety and efficacy of DBS in patients with essential tremor.

METHODS

Patients treated with DBS for essential tremor for at least 8 years were evaluated in the 'on' and 'off' state using the Fahn-Tolosa-Marin tremor rating scale, and their medical records were reviewed to assess complications related to this therapy.

RESULTS

We studied 13 patients (7 men): median age at evaluation 79 years (range 47-88), median age at electrode implantation 68 years (range 37-78) and mean time since electrode implantation 132.54±15.3 months (range 114-164). The difference between the 'off' and 'on' state on the motor items of the tremor rating scale was 41.9% (58.62 vs. 34.08, p<0.001) in the non-blinded and 37.2% (56.07 vs. 35.23, p<0.001) in the blinded rating. DBS provided a functional improvement of 31.7% in the 'on' state (15.07 vs. 22.07, p<0.001). A total non-blinded improvement in the tremor rating scale of 39% was observed in the 'on' state (49.15 vs. 80.69, p<0.001). Dysarthria and disequilibrium were common in patients with bilateral stimulation. A DBS-related surgery (electrode revision or internal pulse generator exchange) was necessary on average every 47.9 months to continue with the DBS therapy.

CONCLUSIONS

Thalamic DBS is a safe and effective therapy in patients with essential tremor followed for up to 13 years.

Differential diagnosis of psychiatric symptoms after deep brain stimulation for movement disorders

OBJECTIVES

The presence of a deep brain stimulator (DBS) in a patient with a movement disorder who develops psychiatric symptoms poses unique diagnostic and therapeutic challenges for the treating clinician. Few sources discuss approaches to diagnosing and treating these symptoms.

MATERIALS AND METHODS

The authors review the literature on psychiatric complications in DBS for movement disorders and propose a heuristic for categorizing symptoms according to their temporal relationship with the DBS implantation process.

RESULTS

Psychiatric symptoms after DBS can be categorized as preimplantation, intra-operative/perioperative, stimulation related, device malfunction, medication related, and chronic stimulation related/long term. Once determined, the specific etiology of a symptom guides the practitioner in treatment.

CONCLUSIONS

A structured approach to psychiatric symptoms in DBS patients allows practitioners to effectively diagnose and treat them when they arise.