Complications of Deep Brain Stimulation (DBS) for dystonia in children - The challenges and 10 year experience in a large paediatric cohort

Outcomes of deep brain stimulation surgery in the management of dystonia in glutaric aciduria type 1

OBJECTIVES

Glutaric aciduria type 1 (GA1) is a rare autosomal recessive organic acidaemia caused by deficiency of the glutaryl-CoA dehydrogenase enzyme. We describe the outcomes following deep brain stimulation (DBS) for the management of dystonia of children and adults with glutaric aciduria type 1 (GA1).

METHODS

Cases with GA1 were identified from the institutional databases of two tertiary movement disorder services. Data were extracted from clinical records using a standardised proforma, including baseline clinical characteristics, imaging and neurophysiological findings, complications post-surgery, and outcomes as measured by the Burke-Fahn-Marsden Dystonia Rating Scale (BMFDRS) motor scores and the Canadian Occupation Performance Measure (COPM).

RESULTS

A total of 15 children were identified aged 3-17.5 with a median age of 11.5 years at neurosurgery, and one adult undergoing DBS aged 31 years. Baseline BMFDRS motor score ranged from 58.5-114, median 105. GMFCS-equivalence level was 5 (i.e. non-ambulant) for 10/16 cases. Surgery was tolerated in all cases without evidence of metabolic decompensation. BFMDRS motor score 1-year post-surgery ranged from 57.5-108.5 (median 97.25) and at last follow-up 57.5-112 (median 104) (no statistically significant change compared to baseline at either time point, P > 0.05). COPM data were available for 11/13 children and young people (CAYP). Clinically significant improvement was reported in 7/11 at 1 year and 8/11 at last follow-up. Four CAYP transitioned to adult services. Death occurred in three cases during follow-up, in no case related to DBS.

CONCLUSION

DBS may be considered as a management option for children with GA1 who have appropriately selected goals for intervention.

Bridging the Gap in FDA Approval for Pediatric Neuromodulation Devices

While neuromodulation devices for managing neurological conditions have significantly advanced, there remains a substantial gap in FDA-approved devices specifically designed for pediatric patients. Devices like deep brain stimulators (DBS), vagus nerve stimulators (VNS), and spinal cord stimulators (SCS) are primarily approved for adults, with few options for children. To meet pediatric needs, off-label use is common; however, unique challenges to pediatric device development-such as ethical concerns, small trial populations, and financial disincentives due to the limited market size-continue to hinder progress. This review examines these barriers to pediatric neuromodulation device development and FDA (Food and Drug Administration) approval, as well as the current efforts, such as FDA initiatives and consortia support, that address regulatory and financial challenges. Furthermore, we discuss pathways like the Humanitarian Device Exemptions and Real-World Evidence programs that aim to streamline the approval process and address unmet clinical needs in pediatric care. Addressing these barriers could expand access to effective neuromodulation treatments and improve patient care.

Deep Brain Stimulation in Pediatric Populations: A Scoping Review of the Clinical Trial Landscape

INTRODUCTION

There has been rapid advancement in the development of deep brain stimulation (DBS) as a treatment option for adults for neurological and neuropsychiatric conditions. Here, we present a scoping review of completed and ongoing clinical trials focused on DBS in pediatric populations, highlighting key knowledge gaps.

METHODS

Three databases (PubMed, OVID, and Embase) and the clinicaltrials.gov registry were queried to identify clinical trials for DBS in pediatric cohorts (age ≤18 years). Prospective and retrospective case series were excluded. No restrictions were placed on the diagnoses or measured clinical outcomes. Individual patient demographics, diagnosis, DBS target, and primary endpoints were extracted and summarized.

RESULTS

A total of 13 clinical trials were included in the final review, consisting of 9 completed trials (357 screened) and 4 ongoing trials (82 screened). Of the completed trials, 6 studied dystonia (both inherited and acquired; participants aged 4-18 years) and 3 studied drug-resistant epilepsy (participants aged 4-17 years). Among the 6 trials for dystonia, 5 used the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) as the primary endpoint. There were a total of 18 adverse events documented across 63 participants, with 5 of 9 studies reporting adverse events. Ongoing clinical trials are evaluating DBS for dystonia (N = 2), epilepsy (N = 1), and self-injurious behavior (N = 1).

CONCLUSIONS

This scoping review summarizes the landscape of clinical trials for DBS in children and youth. In dystonia, further research is warranted with more relevant pediatric outcome measures and for understudied patient subgroups and targets. There are also significant gaps in our understanding of evaluating the role of DBS in other neurological and neurodevelopmental disorders in pediatric populations.

INTRODUCTION

There has been rapid advancement in the development of deep brain stimulation (DBS) as a treatment option for adults for neurological and neuropsychiatric conditions. Here, we present a scoping review of completed and ongoing clinical trials focused on DBS in pediatric populations, highlighting key knowledge gaps.

METHODS

Three databases (PubMed, OVID, and Embase) and the clinicaltrials.gov registry were queried to identify clinical trials for DBS in pediatric cohorts (age ≤18 years). Prospective and retrospective case series were excluded. No restrictions were placed on the diagnoses or measured clinical outcomes. Individual patient demographics, diagnosis, DBS target, and primary endpoints were extracted and summarized.

RESULTS

A total of 13 clinical trials were included in the final review, consisting of 9 completed trials (357 screened) and 4 ongoing trials (82 screened). Of the completed trials, 6 studied dystonia (both inherited and acquired; participants aged 4-18 years) and 3 studied drug-resistant epilepsy (participants aged 4-17 years). Among the 6 trials for dystonia, 5 used the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) as the primary endpoint. There were a total of 18 adverse events documented across 63 participants, with 5 of 9 studies reporting adverse events. Ongoing clinical trials are evaluating DBS for dystonia (N = 2), epilepsy (N = 1), and self-injurious behavior (N = 1).

CONCLUSIONS

This scoping review summarizes the landscape of clinical trials for DBS in children and youth. In dystonia, further research is warranted with more relevant pediatric outcome measures and for understudied patient subgroups and targets. There are also significant gaps in our understanding of evaluating the role of DBS in other neurological and neurodevelopmental disorders in pediatric populations.

Long-Term Globus Pallidus Internus Deep Brain Stimulation in Pediatric Non-Degenerative Dystonia: A Cohort Study and a Meta-Analysis

BACKGROUND

The evidence in the effectiveness of deep brain stimulation in children with medication-refractory non-degenerative monogenic dystonia is heterogeneous and long-term results are sparse.

OBJECTIVES

The objective is to describe long-term outcomes in a single-center cohort and compare our results with a meta-analysis cohort form literature.

METHODS

We performed a retrospective single-center cohort study including consecutive pediatric patients with non-degenerative genetic or idiopathic dystonia treated with globus pallidus internus deep brain stimulation at our center and a systematic review and individual-patient data meta-analysis with the same inclusion criteria. The primary outcome was the change from baseline in the Burke-Fahn-Marsden Dystonia Rating Scale-movement (BFMDRS-M) score.

RESULTS

The clinical cohort included 25 patients with a mean study follow-up of 11.4 years. The meta-analysis cohort included 224 patients with a mean follow-up of 3 years. Overall, the BFMDRS-M mean improvements at 1 year and at last follow-up were 41% and 33% in the clinical cohort and 58.9% and 57.2% in the meta-analysis cohort, respectively. TOR1A-dystonia showed the greatest and most stable BFMDRS-M improvement in both cohorts at 1 year and at last follow-up (76.3% and 74.3% in the clinical cohort; 69.6% and 67.3% in the meta-analysis cohort), followed by SGCE-dystonia (63% and 63.9% in the meta-analysis cohort). THAP1-dystonia (70.1% and 29.8% in the clinical cohort; 52.3% and 42.0% in the meta-analysis cohort) and KMT2B-dystonia (33.3% and 41.3% in the clinical cohort; 38.0% and 26.7% in the meta-analysis cohort) showed a less pronounced or sustained response.

CONCLUSION

Globus pallidus deep brain stimulation long-term treatment seems effective with a possible gene-specific differential effect. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Recommendations for the Prevention and Management of Deep Brain Stimulation Infections Based on 26-Year Single-Center Experience

INTRODUCTION

Infections related to deep brain stimulation (DBS) can lead to discontinuation of the treatment and increased morbidity. Various measures of reducing infection rates have been proposed in the literature, but scientific consensus is lacking. The aim of this study was to report a 26-year single center experience of DBS infections and provide recommendations for the prevention and management of them.

METHODS

The retrospective analysis consisted of 978 DBS surgeries performed at Oulu University Hospital (OUH) from 1997 to 2022. This included 342 primary or reimplantations of DBS electrodes and 559 primary or reimplantations of implantable pulse generator (IPG). Infections within approximately 1 year after the surgery without secondary cause were considered surgical-site infections (SSIs). χ2 test was used to compare infection rates before and after 2013, when the systematic implementation of infection prevention measures was started.

RESULTS

A total of 35 DBS implants were found to be infected. The number of SSIs was 30, of which 29 were originally operated in OUH leading to a center-specific infection rate of 3.1%. Of the SSIs, 17.2% occurred after IPG replacement. Staphylococcus aureus was found in 75.0% of cultures and 32.1% were mixed infections. The treatment of SSIs included aggressive surgical revision combined with cefuroxime and vancomycin antibiotics, as most patients in the initial conservative treatment group eventually required surgical revision. A statistically significant difference in infection rates before and after the implementation of preventative measures was not observed (risk ratio 2.20, 95% confidence interval 0.94-5.75, p = 0.051), despite over two-fold difference in the incidence of SSIs.

CONCLUSION

Our findings show that the rates of surgical infections are low in modern DBS, but due to their serious consequences, preventative measures should be implemented. We highlight that mixed infections should be accounted for in the antibiotic selection. Furthermore, our treatment recommendation includes aggressive surgical revision combined with antibiotic treatment.

Neurosurgical and pharmacological management of dystonia

Dystonia characterizes a group of neurological movement disorders characterized by abnormal muscle movements, often with repetitive or sustained contraction resulting in abnormal posturing. Different types of dystonia present based on the affected body regions and play a prominent role in determining the potential efficacy of a given intervention. For most patients afflicted with these disorders, an exact cause is rarely identified, so treatment mainly focuses on symptomatic alleviation. Pharmacological agents, such as oral anticholinergic administration and botulinum toxin injection, play a major role in the initial treatment of patients. In more severe and/or refractory cases, focal areas for neurosurgical intervention are identified and targeted to improve quality of life. Deep brain stimulation (DBS) targets these anatomical locations to minimize dystonia symptoms. Surgical ablation procedures and peripheral denervation surgeries also offer potential treatment to patients who do not respond to DBS. These management options grant providers and patients the ability to weigh the benefits and risks for each individual patient profile. This review article explores these pharmacological and neurosurgical management modalities for dystonia, providing a comprehensive assessment of each of their benefits and shortcomings.

Protocol for combined N-of-1 trials to assess cerebellar neurostimulation for movement disorders in children and young adults with dyskinetic cerebral palsy

BACKGROUND

Movement and tone disorders in children and young adults with cerebral palsy are a great source of disability. Deep brain stimulation (DBS) of basal ganglia targets has a major role in the treatment of isolated dystonias, but its efficacy in dyskinetic cerebral palsy (DCP) is lower, due to structural basal ganglia and thalamic damage and lack of improvement of comorbid choreoathetosis and spasticity. The cerebellum is an attractive target for DBS in DCP since it is frequently spared from hypoxic ischemic damage, it has a significant role in dystonia network models, and small studies have shown promise of dentate stimulation in improving CP-related movement and tone disorders.

METHODS

Ten children and young adults with DCP and disabling movement disorders with or without spasticity will undergo bilateral DBS in the dorsal dentate nucleus, with the most distal contact ending in the superior cerebellar peduncle. We will implant Medtronic Percept, a bidirectional neurostimulator that can sense and store brain activity and deliver DBS therapy. The efficacy of cerebellar DBS in improving quality of life and motor outcomes will be tested by a series of N-of-1 clinical trials. Each N-of-1 trial will consist of three blocks, each consisting of one month of effective stimulation and one month of sham stimulation in a random order with weekly motor and quality of life scales as primary and secondary outcomes. In addition, we will characterize abnormal patterns of cerebellar oscillatory activity measured by local field potentials from the intracranial electrodes related to clinical assessments and wearable monitors. Pre- and 12-month postoperative volumetric structural and functional MRI and diffusion tensor imaging will be used to identify candidate imaging markers of baseline disease severity and response to DBS.

DISCUSSION

Our goal is to test a cerebellar neuromodulation therapy that produces meaningful changes in function and well-being for people with CP, obtain a mechanistic understanding of the underlying brain network disorder, and identify physiological and imaging-based predictors of outcomes useful in planning further studies.

TRIAL REGISTRATION

ClinicalTrials.gov NCT06122675, first registered November 7, 2023.

Protocol for combined N-of-1 trials to assess cerebellar neurostimulation for movement disorders in children and young adults with dyskinetic cerebral palsy

Background

Movement and tone disorders in children and young adults with cerebral palsy are a great source of disability. Deep brain stimulation (DBS) of basal ganglia targets has a major role in the treatment of isolated dystonias, but its efficacy in dyskinetic cerebral palsy (DCP) is lower, due to structural basal ganglia and thalamic damage and lack of improvement of comorbid choreoathetosis and spasticity. The cerebellum is an attractive target for DBS in DCP since it is frequently spared from hypoxic ischemic damage, it has a significant role in dystonia network models, and small studies have shown promise of dentate stimulation in improving CP-related movement and tone disorders.

Methods

Ten children and young adults with DCP and disabling movement disorders with or without spasticity will undergo bilateral DBS in the dorsal dentate nucleus, with the most distal contact ending in the superior cerebellar peduncle. We will implant Medtronic Percept, a bidirectional neurostimulator that can sense and store brain activity and deliver DBS therapy. The efficacy of cerebellar DBS in improving quality of life and motor outcomes will be tested by a series of N-of-1 clinical trials. Each N-of-1 trial will consist of three blocks, each consisting of one month of effective stimulation and one month of sham stimulation in a random order with weekly motor and quality of life scales as primary and secondary outcomes. In addition, we will characterize abnormal patterns of cerebellar oscillatory activity measured by local field potentials from the intracranial electrodes related to clinical assessments and wearable monitors. Pre- and 12-month postoperative volumetric structural and functional MRI and diffusion tensor imaging will be used to identify candidate imaging markers of baseline disease severity and response to DBS.

Discussion

Our goal is to test a cerebellar neuromodulation therapy that produces meaningful changes in function and well-being for people with CP, obtain a mechanistic understanding of the underlying brain network disorder, and identify physiological and imaging-based predictors of outcomes useful in planning further studies.

Trial registration

ClinicalTrials.gov NCT06122675, first registered November 7, 2023.

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.

Stereotactic Awake Basal Ganglia Electrophysiological Recording and Stimulation (SABERS): A Novel Staged Procedure for Personalized Targeting of Deep Brain Stimulation in Pediatric Movement and Neuropsychiatric Disorders

Selection of targets for deep brain stimulation (DBS) has been based on clinical experience, but inconsistent and unpredictable outcomes have limited its use in patients with heterogeneous or rare disorders. In this large case series, a novel staged procedure for neurophysiological assessment from 8 to 12 temporary depth electrodes is used to select targets for neuromodulation that are tailored to each patient's functional needs. Thirty children and young adults underwent deep brain stimulation target evaluation with the new procedure: Stereotactic Awake Basal ganglia Electrophysiological Recording and Stimulation (SABERS). Testing is performed in an inpatient neuromodulation monitoring unit over 5-7 days, and results guide the decision to proceed and the choice of targets for permanent deep brain stimulation implantation. Results were evaluated 3-6 months postoperatively with the Burke-Fahn-Marsden Dystonia Rating Scale and the Barry-Albright Dystonia Scale. Stereotactic Awake Basal ganglia Electrophysiological Recording and Stimulation testing allowed modulation to be tailored to specific neurologic deficits in a heterogeneous population, including subjects with primary dystonia, secondary dystonia, and Tourette syndrome. All but one subject were implanted with 4 permanent deep brain stimulation leads. Results showed significant improvement on both scales at postoperative follow-up. No significant adverse events occurred. Use of the Stereotactic Awake Basal ganglia Electrophysiological Recording and Stimulation protocol with evaluation in the neuromodulation monitoring unit is feasible and results in significant patient benefit compared with previously published results in these populations. This new technique supports a significant expansion of functional neurosurgery to predict effective stimulation targets in a wide range of disorders of brain function, including those for which the optimal target is not yet known.

Rescuing Infected Deep Brain Stimulation Therapies in Severely Affected Patients

(1) Background: Infections in deep brain stimulation (DBS) hardware, while an undesired complication of DBS surgeries, can be effectively addressed. Minor infections are typically treated with wound revision and IV antibiotics. However, when visible hardware infection occurs, most centers opt for complete removal, leaving the patient in a preoperative state and necessitating post-removal care. To avoid the need for such care, a novel technique was developed. (2) Methods: The electrodes are placed at the exact same spot and then led to the contralateral side. new extensions and a new generator contralateral to the infection as well. Subsequently, the infected system is removed. This case series includes six patients. (3) Results: The average duration of DBS system implantation before the second surgery was 272 days. Only one system had to be removed after 18 months due to reoccurring infection; the others remained unaffected. Laboratory alterations and pathogens were identified in only half of the patients. (4) Conclusions: The described surgical technique proves to be safe, well tolerated, and serves as a viable alternative to complete system removal. Importantly, it effectively prevents the need of post-removal care for patients.

Stereotactic Staged Asymmetric Bilateral Radiofrequency Lesioning for Parkinson's Disease

INTRODUCTION

Parkinson's disease (PD) is one of the most common neurodegenerative progressive disorders. Despite the dominance of neurostimulation technology, stereotactic lesioning operations play a significant role in the treatment of PD. The aim of the study was to evaluate the effectiveness and safety of staged bilateral asymmetric radiofrequency (RF) stereotactic lesioning in a highly selected group of PD patients.

MATERIAL AND METHODS

A retrospective review of 418 consecutive patients undergoing stereotactic ablation for advanced PD at our institution revealed 28 patients who underwent staged asymmetric bilateral ablation. In this subset, after initial RF thalamotomy, contralateral pallidotomy was performed in 16 (57.1%) patients (group Vim-GPi), and contralateral lesion of the subthalamic nucleus (STN) was performed in 12 (32.9%) patients (group Vim-STN). The mean duration of disease before the first surgery was 9.9 ± 0.8 years. The mean interval between the two operations was 3.5 ± 0.4 years (range, 1-10 years); in the Vim-GPi group, it was 3.1 ± 0.4 years; and in the Vim-STN group, it was 4.3 ± 0.1 years. After the second operation, the long-term follow-up lasted from 1 to 8 years (mean 4.8 ± 0.5 years). All patients were evaluated 1 year after the second operation.

RESULTS

One year after staged bilateral lesioning, the mean tremor score improved from baseline, prior to the first operation, from 19.8 to 3.8 (improvement of 81%), the overall mean rigidity score improved from 11.0 to 3.7 (improvement of 66%), and hypokinesia improved from 14.8 to 8.9 (improvement of 40%). One year after staged bilateral lesioning, the total UPDRS score improved in the Vim-GPi group by 47% in the OFF and 45.9% in the ON states. In the Vim-STN group, the total UPDRS score improved from baseline, prior to the first operation, by 44.8% in the OFF and 51.6% in the ON states. Overall, levodopa dose was reduced by 43.4%. Neurological complications were observed in 4 (14.3%) cases; among them, 1 (3.6%) patient had permanent events related to local ischemia after pallidotomy.

CONCLUSION

Staged asymmetric bilateral stereotactic RF lesioning can be a safe and effective method in highly selected patients with advanced PD, particularly where deep brain stimulation is not available or desirable. Careful identification and selection of patients for ablative surgery allow achieving optimal results in the treatment of PD with bilateral symptoms.

Deep Brain Stimulation for Refractory Status Dystonicus in Children: Multicenter Case Series and Systematic Review

OBJECTIVE

We sought to better understand the workflow, outcomes, and complications of deep brain stimulation (DBS) for pediatric status dystonicus (SD). We present a systematic review, alongside a multicenter case series of pediatric patients with SD treated with DBS.

METHODS

We collected individual data regarding treatment, stimulation parameters, and dystonia severity for a multicenter case series (n = 8) and all previously published cases (n = 77). Data for case series were used to create probabilistic voxelwise maps of stimulated tissue associated with dystonia improvement.

RESULTS

In our institutional series, DBS was implanted a mean of 25 days after SD onset. Programming began a mean of 1.6 days after surgery. All 8 patients in our case series and 73 of 74 reported patients in the systematic review had resolution of their SD with DBS, most within 2 to 4 weeks of surgery. Mean follow-up for patients in the case series was 16 months. DBS target for all patients in the case series and 68 of 77 in our systematic review was the globus pallidus pars interna (GPi). In our case series, stimulation of the posterior-ventrolateral GPi was associated with improved dystonia. Mean dystonia improvement was 32% and 51% in our institutional series and systematic review, respectively. Mortality was 4% in the review, which is lower than reported for treatment with pharmacotherapy alone (10-12.5%).

INTERPRETATION

DBS is a feasible intervention with potential to reverse refractory pediatric SD and improve survival. More work is needed to increase awareness of DBS in this setting, so that it can be implemented in a timely manner. ANN NEUROL 2023.

Neurosurgical management of elevated tone in childhood: interventions, indications and uncertainties

Elevated tone (hypertonia) is a common problem in children with physical disabilities. Medications intended to reduce tone often have limited efficacy, with use further limited by a significant side effect profile. Consequently, there has been growing interest in the application of Neurosurgical Interventions for the Management of Posture and Tone (NIMPTs). Three main procedures are now commonly used: selective dorsal rhizotomy (SDR), intrathecal baclofen (ITB) and deep brain stimulation (DBS). This review compares these interventions, along with discussion on the potential role of lesioning surgery. These interventions variably target spasticity and dystonia, acting at different points in the distributed motor network. SDR, an intervention for reducing spasticity, is most widely used in carefully selected ambulant children with cerebral palsy. ITB is more commonly used for children with more severe disability, typically non-ambulant, and can improve both dystonia and spasticity. DBS is an intervention which may improve dystonia. In children with certain forms of genetic dystonia DBS may dramatically improve dystonia. For other causes of dystonia, and in particular dystonia due to acquired brain injury, improvements following surgery are more modest and variable. These three interventions vary in terms of their side-effect profile and reversibility. There are currently populations of children for who it is unclear which intervention should be considered (SDR vs ITB, or ITB vs DBS). Concerns have been raised as to the equity of access to NIMPTs for children across the UK, and whether the number of surgeries performed each year meets the clinical need.

Long-Term Follow-Up of Pediatric Patients with Dyskinetic Cerebral Palsy and Deep Brain Stimulation

BACKGROUND

Deep brain stimulation (DBS) has been increasingly used in the management of dyskinetic cerebral palsy (DCP). Data on long-term effects and the safety profile are rare.

OBJECTIVES

We assessed the efficacy and safety of pallidal DBS in pediatric patients with DCP.

METHODS

The STIM-CP trial was a prospective, single-arm, multicenter study in which patients from the parental trial agreed to be followed-up for up to 36 months. Assessments included motor and non-motor domains.

RESULTS

Of the 16 patients included initially, 14 (mean inclusion age 14 years) were assessed. There was a significant change in the (blinded) ratings of the total Dyskinesia Impairment Scale at 36 months. Twelve serious adverse events (possibly) related to treatment were documented.

CONCLUSION

DBS significantly improved dyskinesia, but other outcome parameters did not change significantly. Investigations of larger homogeneous cohorts are needed to further ascertain the impact of DBS and guide treatment decisions in DCP. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Deep Brain Stimulation for Pediatric Dystonia: Clinicians' Perspectives on the Most Pressing Ethical Challenges

INTRODUCTION

Pediatric deep brain stimulation (pDBS) is commonly used to manage treatment-resistant primary dystonias with favorable results and more frequently used for secondary dystonia to improve quality of life. There has been little systematic empirical neuroethics research to identify ethical challenges and potential solutions to ensure responsible use of DBS in pediatric populations.

METHODS

Clinicians (n = 29) who care for minors with treatment-resistant dystonia were interviewed for their perspectives on the most pressing ethical issues in pDBS.

RESULTS

Using thematic content analysis to explore salient themes, clinicians identified four pressing concerns: (1) uncertainty about risks and benefits of pDBS (22/29; 72%) that poses a challenge to informed decision-making; (2) ethically navigating decision-making roles (15/29; 52%), including how best to integrate perspectives from diverse stakeholders (patient, caregiver, clinician) and how to manage surrogate decisions on behalf of pediatric patients with limited capacity to make autonomous decisions; (3) information scarcity effects on informed consent and decision quality (15/29; 52%) in the context of patient and caregivers' expectations for treatment; and (4) narrow regulatory status and access (7/29; 24%) such as the lack of FDA-approved indications that contribute to decision-making uncertainty and liability and potentially limit access to DBS among patients who may benefit from it.

CONCLUSION

These results suggest that clinicians are primarily concerned about ethical limitations of making difficult decisions in the absence of informational, regulatory, and financial supports. We discuss two solutions already underway, including supported decision-making to address uncertainty and further data sharing to enhance clinical knowledge and discovery.

Surgical treatment of movement disorders in neurometabolic conditions

Refractory movement disorders are a common feature of inborn errors of metabolism (IEMs), significantly impacting quality of life and potentially leading to life-threatening complications such as status dystonicus. Surgical techniques, including deep brain stimulation (DBS) and lesioning techniques, represent an additional treatment option. However, the application and benefits of these procedures in neurometabolic conditions is not well understood. This results in challenges selecting surgical candidates and counseling patients preoperatively. In this review, we explore the literature of surgical techniques for the treatment of movement disorders in IEMs. Globus pallidus internus DBS has emerged as a beneficial treatment option for dystonia in Panthotate-Kinase-associated Neurodegeneration. Additionally, several patients with Lesch-Nyhan Disease have shown improvement following pallidal stimulation, with more robust effects on self-injurious behavior than dystonia. Although there are numerous reports describing benefits of DBS for movement disorders in other IEMs, the sample sizes have generally been small, limiting meaningful conclusions. Currently, DBS is preferred to lesioning techniques. However, successful use of pallidotomy and thalamotomy in neurometabolic conditions has been reported and may have a role in selected patients. Surgical techniques have also been used successfully in patients with IEMs to treat status dystonicus. Advancing our knowledge of these treatment options could significantly improve the care for patients with neurometabolic conditions.

Use of Invasive Brain-Computer Interfaces in Pediatric Neurosurgery: Technical and Ethical Considerations

Invasive brain-computer interfaces hold promise to alleviate disabilities in individuals with neurologic injury, with fully implantable brain-computer interface systems expected to reach the clinic in the upcoming decade. Children with severe neurologic disabilities, like quadriplegic cerebral palsy or cervical spine trauma, could benefit from this technology. However, they have been excluded from clinical trials of intracortical brain-computer interface to date. In this manuscript, we discuss the ethical considerations related to the use of invasive brain-computer interface in children with severe neurologic disabilities. We first review the technical hardware and software considerations for the application of intracortical brain-computer interface in children. We then discuss ethical issues related to motor brain-computer interface use in pediatric neurosurgery. Finally, based on the input of a multidisciplinary panel of experts in fields related to brain-computer interface (functional and restorative neurosurgery, pediatric neurosurgery, mathematics and artificial intelligence research, neuroengineering, pediatric ethics, and pragmatic ethics), we then formulate initial recommendations regarding the clinical use of invasive brain-computer interfaces in children.

Positioning Transclival Tumor-Treating Fields for the Treatment of Diffuse Intrinsic Pontine Gliomas

Diffuse intrinsic pontine glioma (DIPG) carries an extremely poor prognosis, with 2-year survival rates of <10% despite the maximal radiation therapy. DIPG cells have previously been shown to be sensitive to low-intensity electric fields in vitro. Accordingly, we sought to determine if the endoscopic endonasal (EE) implantation of an electrode array in the clivus would be feasible for the application of tumor-treating fields (TTF) in DIPG. Anatomic constraints are the main limitation in pediatric EE approaches. In our Boston Children’s Hospital’s DIPG cohort, we measured the average intercarotid distance (1.68 ± 0.36 cm), clival width (1.62 ± 0.19 cm), and clival length from the base of the sella (1.43 ± 0.69 cm). Using a linear regression model, we found that only clival length and sphenoid pneumatization were significantly associated with age (R2 = 0.568, p = 0.005 *; R2 = 0.605, p = 0.0002 *). Critically, neither of these parameters represent limitations to the implantation of a device within the dimensions of those currently available. Our findings confirm that the anatomy present within this age group is amenable to the placement of a 2 × 1 cm electrode array in 94% of patients examined. Our work serves to demonstrate the feasibility of implantable transclival devices for the provision of TTFs as a novel adjunctive therapy for DIPG.

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.

Elective and Emergency Deep Brain Stimulation in Refractory Pediatric Monogenetic Movement Disorders Presenting with Dystonia: Current Practice Illustrated by Two Cases

BACKGROUND

Dystonia is characterized by sustained or intermittent muscle contractions, leading to abnormal posturing and twisting movements. In pediatric patients, dystonia often negatively influences quality of life. Pharmacological treatment for dystonia is often inadequate and causes adverse effects. Deep brain stimulation (DBS) appears to be a valid therapeutic option for pharmacoresistant dystonia in children.

METHODS

To illustrate the current clinical practice, we hereby describe two pediatric cases of monogenetic movement disorders presenting with dystonia and treated with DBS. We provide a literature review of similar previously described cases and on different clinical aspects of DBS in pediatric dystonia.

RESULTS

The first patient, a 6-year-old girl with severe dystonia, chorea, and myoclonus due to an ADCY5 gene mutation, received DBS in an elective setting. The second patient, an 8-year-old boy with GNAO1-related dystonia and chorea, underwent emergency DBS due to a pharmacoresistant status dystonicus. A significant amelioration of motor symptoms (65% on the Burke-Fahn-Marsden Dystonia Rating Scale) was observed postoperatively in the first patient and her personal therapeutic goals were achieved. DBS was previously reported in five patients with ADCY5-related movement disorders, of which three showed objective improvement. Emergency DBS in our second patient resulted in the successful termination of his GNAO1-related status dystonicus, this being the eighth case reported in the literature.

CONCLUSION

DBS can be effective in monogenetic pediatric dystonia and should be considered early in the disease course. To better evaluate the effects of DBS on patients' functioning, patient-centered therapeutic goals should be discussed in a multidisciplinary approach.

Deep brain stimulation in a young child with GNAO1 mutation – Feasible and helpful

Background:

GNAO1 is an emerging disorder characterized with hypotonia, developmental delay, epilepsy, and movement disorder, which can be potentially life threatening during acute exacerbation. In the USA, deep brain stimulation (DBS) has been licensed for treating children with chronic, treatment-resistant primary dystonia, who are 7 years old or older.

Case Description:

A 4-year-old girl diagnosed to have GNAO1-related dyskinesia and severe global developmental delay. She had severe dyskinesia precipitated by intercurrent infection, requiring prolonged intensive care for heavy sedation and related complications. Her dyskinesia improved dramatically after DBS implantation. Technical difficulties and precautions of DBS in preschool children were discussed.

Conclusion:

DBS should be considered early in the treatment of drug-resistant movement disorders in young children with GNAO1, especially after dyskinetic crisis, as they tend to recur. Presurgical counseling to parents and close monitoring of complications is also important in the process.

A review on magnetic and spintronic neurostimulation: challenges and prospects

In the treatment of neurodegenerative, sensory and cardiovascular diseases, electrical probes and arrays have shown quite a promising success rate. However, despite the outstanding clinical outcomes, their operation is significantly hindered by non-selective control of electric fields. A promising alternative is micromagnetic stimulation (μMS) due to the high permeability of magnetic field through biological tissues. The induced electric field from the time-varying magnetic field generated by magnetic neurostimulators is used to remotely stimulate neighboring neurons. Due to the spatial asymmetry of the induced electric field, high spatial selectivity of neurostimulation has been realized. Herein, some popular choices of magnetic neurostimulators such as microcoils (μcoils) and spintronic nanodevices are reviewed. The neurostimulator features such as power consumption and resolution (aiming at cellular level) are discussed. In addition, the chronic stability and biocompatibility of these implantable neurostimulator are commented in favor of further translation to clinical settings. Furthermore, magnetic nanoparticles (MNPs), as another invaluable neurostimulation material, has emerged in recent years. Thus, in this review we have also included MNPs as a remote neurostimulation solution that overcomes physical limitations of invasive implants. Overall, this review provides peers with the recent development of ultra-low power, cellular-level, spatially selective magnetic neurostimulators of dimensions within micro- to nano-range for treating chronic neurological disorders. At the end of this review, some potential applications of next generation neuro-devices have also been discussed.

Strength-frequency curve for micromagnetic neurostimulation through excitatory postsynaptic potentials (EPSPs) on rat hippocampal neurons and numerical modeling of magnetic microcoil (μcoil)

OBJECTIVE

The objective of this study was to measure the effect of micromagnetic stimulation (μMS) on hippocampal neurons, by using single microcoil (μcoil) prototype, Magnetic Pen (MagPen). MagPen will be used to stimulate the CA3 magnetically and excitatory post synaptic potential (EPSP) measurements will be made from the CA1. The threshold for μMS as a function of stimulation frequency of the current driving the µcoil will be demonstrated. Finally, the optimal stimulation frequency of the current driving the μcoil to minimize power will be estimated.

APPROACH

A biocompatible prototype, MagPen was built, and customized such that it is easy to adjust the orientation of the μcoil over the hippocampal tissue in an in vitro setting. Finite element modeling (FEM) of the μcoil was performed to estimate the spatial profiles of the magnetic flux density (in T) and the induced electric fields (in V/m). The induced electric field profiles generated at different values of current applied to the µcoil whether can elicit a neuron response was validated by numerical modeling. The modeling settings were replicated in experiments on rat hippocampal neurons.

MAIN RESULTS

The preferred orientation of MagPen over the Schaffer Collateral fibers was demonstrated such that they elicit a neuron response. The recorded EPSPs from CA1 due to μMS at CA3 were validated by applying tetrodotoxin (TTX). Finally, it was interpreted through numerical analysis that increasing frequency of the current driving the μcoil, led to a decrease in the current amplitude threshold for μMS.

SIGNIFICANCE

This work reports that μMS can be used to evoke population EPSPs in the CA1 of hippocampus. It demonstrates the strength-frequency curve for µMS and its unique features related to orientation dependence of the µcoils, spatial selectivity and distance dependence. Finally, the challenges related to µMS experiments were studied including ways to overcome them.

Starting a DBS service for children: It's not the latitude but the attitude - Establishment of the paediatric DBS centre in Northern Finland

OBJECTIVE

Paediatric movement disorder patients can benefit from deep brain stimulation (DBS) treatment and it should be offered in a timely manner. In this paper we describe our experience establishing a DBS service for paediatric patients.

METHODS

We set out to establish a paediatric DBS (pDBS) procedure in Oulu University Hospital in northern Finland, where up to this point DBS treatment for movement disorders had been available for adult patients. Collaboration with experienced centres aided in the process.

RESULTS

A multidisciplinary team was assembled and a systematic protocol for patient evaluation and treatment was created, with attention to special features of the regional health care system. All of our first paediatric patients had very severe movement disorders, which is typical for a new DBS centre. The patients benefitted from pDBS treatment despite variable aetiologies of movement disorders, which included cerebral palsy and rare genetic disorders with variants in PDE10A, TPK1 and ARX. We also present our high-quality paediatric MR-imaging protocol with tractography.

CONCLUSIONS

Establishment of a pDBS centre requires expertise in classification of paediatric movement disorders, longstanding experience in adult DBS and a committed multidisciplinary team. Besides high-quality imaging and a skilled neurosurgery team, careful patient selection, realistic treatment goals and experience in rehabilitation are imperative in pDBS treatment.

Quality of Life after Deep Brain Stimulation of Pediatric Patients With Dyskinetic Cerebral Palsy: A Prospective, Single-Arm, Multicenter Study With a Subsequent Randomized Double-Blind Crossover (STIM-CP)

BACKGROUND

Patients with dyskinetic cerebral palsy are often severely impaired with limited treatment options. The effects of deep brain stimulation (DBS) are less pronounced than those in inherited dystonia but can be associated with favorable quality of life outcomes even in patients without changes in dystonia severity.

OBJECTIVE

The aim is to assess DBS effects in pediatric patients with pharmacorefractory dyskinetic cerebral palsy with focus on quality of life.

METHODS

The method used is a prospective, single-arm, multicenter study. The primary endpoint is improvement in quality of life (CPCHILD [Caregiver Priorities & Child Health Index of Life with Disabilities]) from baseline to 12 months under therapeutic stimulation. The main key secondary outcomes are changes in Burke-Fahn-Marsden Dystonia Rating Scale, Dyskinesia Impairment Scale, Gross Motor Function Measure-66, Canadian Occupational Performance Measure (COPM), and Short-Form (SF)-36. After 12 months, patients were randomly assigned to a blinded crossover to receive active or sham stimulation for 24 hours each. Severity of dystonia and chorea were blindly rated. Safety was assessed throughout. The trial was registered at ClinicalTrials.gov, number NCT02097693.

RESULTS

Sixteen patients (age: 13.4 ± 2.9 years) were recruited by seven clinical sites. Primary outcome at 12-month follow-up is as follows: mean CPCHILD increased by 4.2 ± 10.4 points (95% CI [confidence interval] -1.3 to 9.7; P = 0.125); among secondary outcomes: improvement in COPM performance measure of 1.1 ± 1.5 points (95% CI 0.2 to 1.9; P = 0.02) and in the SF-36 physical health component by 5.1 ± 6.2 points (95% CI 0.7 to 9.6; P = 0.028). Otherwise, there are no significant changes.

CONCLUSION

Evidence to recommend DBS as routine treatment to improve quality of life in pediatric patients with dyskinetic cerebral palsy is not yet sufficient. Extended follow-up in larger cohorts will determine the impact of DBS further to guide treatment decisions in these often severely disabled patients.

Pressing ethical issues in considering pediatric deep brain stimulation for obsessive-compulsive disorder

BACKGROUND

Refractory obsessive-compulsive disorder (OCD) among adults is the first psychiatric indication of deep brain stimulation (DBS) to receive an FDA Humanitarian Device Exemption (HDE). Given the HDE approval and encouraging evidence that has since emerged, exploration of DBS for OCD may expand to adolescents in the future. More than 100,000 adolescents in the U.S. suffer from refractory OCD, and there is already a precedent for the transition of DBS in adults to children in the case of dystonia. However, the risk-benefit analysis of pediatric DBS for OCD may be more complex and raise different ethical questions compared to pediatric DBS for dystonia.

OBJECTIVE

This study aimed to gain insight into pressing ethical issues related to using DBS in adolescents with OCD.

METHODS

Semi-structured interviews were conducted with clinicians (n = 25) caring for pediatric patients with refractory OCD. Interview transcripts were coded with MAXQDA 2018 software and analyzed using thematic content analysis to identify emergent themes.

RESULTS

Five central themes were identified in clinician responses, three of which were exacerbated in the pediatric DBS setting. Clinicians expressed concerns related to conditions of decision-making including adolescents' capacity to assent (80%), the lack of evidence about the outcomes and potential unknown effects of using DBS in adolescents with OCD (68%), and the importance of exhausting other treatment options before considering DBS (20%).

CONCLUSIONS

Strategies to address clinician concerns include implementation of validated decision support tools and further research into the outcomes of pediatric DBS for OCD to establish clear guidelines for patient selection.

Pharmacological and neurosurgical interventions for individuals with cerebral palsy and dystonia: a systematic review update and meta-analysis

AIM

To update a systematic review of evidence published up to December 2015 for pharmacological/neurosurgical interventions among individuals with cerebral palsy (CP) and dystonia.

METHOD

Searches were updated (January 2016 to May 2020) for oral baclofen, trihexyphenidyl, benzodiazepines, clonidine, gabapentin, levodopa, botulinum neurotoxin (BoNT), intrathecal baclofen (ITB), and deep brain stimulation (DBS), and from database inception for medical cannabis. Eligible studies included at least five individuals with CP and dystonia and reported on dystonia, goal achievement, motor function, pain/comfort, ease of caregiving, quality of life (QoL), or adverse events. Evidence certainty was evaluated using GRADE.

RESULTS

Nineteen new studies met inclusion criteria (two trihexyphenidyl, one clonidine, two BoNT, nine ITB, six DBS), giving a total of 46 studies (four randomized, 42 non-randomized) comprising 915 participants when combined with those from the original systematic review. Very low certainty evidence supported improved dystonia (clonidine, ITB, DBS) and goal achievement (clonidine, BoNT, ITB, DBS). Low to very low certainty evidence supported improved motor function (DBS), pain/comfort (clonidine, BoNT, ITB, DBS), ease of caregiving (clonidine, BoNT, ITB), and QoL (ITB, DBS). Trihexyphenidyl, clonidine, BoNT, ITB, and DBS may increase adverse events. No studies were identified for benzodiazepines, gabapentin, oral baclofen, and medical cannabis.

INTERPRETATION

Evidence evaluating the use of pharmacological and neurosurgical management options for individuals with CP and dystonia is limited to between low and very low certainty. What this paper adds Meta-analysis suggests that intrathecal baclofen (ITB) and deep brain stimulation (DBS) may improve dystonia and pain. Meta-analysis suggests that DBS may improve motor function. Clonidine, botulinum neurotoxin, ITB, and DBS may improve achievement of individualized goals. ITB and DBS may improve quality of life. No direct evidence is available for oral baclofen, benzodiazepines, gabapentin, or medical cannabis.

Deep brain stimulation in Lesch-Nyhan disease: outcomes from the patient's perspective

AIM

To provide insight into outcome and long-term safety and efficacy of deep brain stimulation (DBS), from the perspective of individuals with Lesch-Nyhan disease (LND) and their families.

METHOD

We used patient-centered outcome measures to assess long-term outcomes of DBS for 14 individuals (mean [SD] age 10y 10mo [5y 6mo], range 5-23y, all males) with LND, after an average duration of 5y 6mo (range 11mo-10y 5mo) after surgery. We compared these results with a comprehensive review of previously published cases.

RESULTS

Patients and their families reported that DBS of the globus pallidus can be effective both for motor and behavioral disturbances in LND. However, outcome measures were often not significantly changed owing to substantial variability among individuals, and were overall less positive than in previous reports based on clinician assessments. In addition, there was an unexpectedly high rate of adverse events, tempering overall enthusiasm for the procedure.

INTERPRETATION

Although DBS might be an effective treatment for LND, more research is needed to understand the reasons for response variability and the unusually high rates of adverse events before DBS can be recommended for these patients. What this paper adds Individuals with Lesch-Nyhan disease and their families report variable efficacy of deep brain stimulation. Long-term outcomes are associated with a high adverse event rate.

Deep Brain Stimulation for Pediatric Dystonia

Dystonia is one of the most common pediatric movement disorders and can have a profound impact on the lives of children and their caregivers. Response to pharmacologic treatment is often unsatisfactory. Deep brain stimulation (DBS) has emerged as a promising treatment option for children with medically refractory dystonia. In this review we highlight the relevant literature related to DBS for pediatric dystonia, with emphasis on the background, indications, prognostic factors, challenges, and future directions of pediatric DBS.

Deep brain stimulation in the management of paediatric neuropsychiatric conditions: Current evidence and future directions

INTRODUCTION

Neurosurgery has provided an alternative option for patients with refractory psychiatric indications. Lesion procedures were the initial techniques used, but deep brain stimulation (DBS) has the advantage of relative reversibility and adjustability. This review sets out to delineate the current evidence for DBS use in psychiatric conditions, with an emphasis on the paediatric population, highlighting pitfalls and opportunities.

METHODS

A systematic review of the literature was conducted on studies reporting the use of DBS in the management of psychiatric disorders. The PRISMA guidelines were employed to structure the review of the literature. Data was discussed focusing on the indications for DBS management of psychiatric conditions in the paediatric age group.

RESULTS

A total of seventy-three full-text papers reported the use of DBS surgery for the management of psychiatric conditions matching the inclusion criteria. The main indications were Tourette Syndrome (GTS) (15 studies), Obsessive Compulsive Disorder (OCD) (20), Treatment Resistant Depression (TRD) (27), Eating Disorders (ED) (7) and Aggressive Behaviour and self-harm (AB) (4). Out of these, only 11 studies included patients in the paediatric age group (≤18 years-old). Among the paediatric patients, the indications for surgery included GTS, AB and ED.

CONCLUSIONS

The application of deep brain stimulation for psychiatric indications has progressed at a steady pace in the adult population and at a much slower pace in the paediatric population. Future studies in children should be done in a trial setting with strict and robust criteria. A move towards personalising DBS therapy with new stimulation paradigms will provide new frontiers and possibilities in this growing field.

Dystonia Management: What to Expect From the Future? The Perspectives of Patients and Clinicians Within DystoniaNet Europe

Improved care for people with dystonia presents a number of challenges. Major gaps in knowledge exist with regard to how to optimize the diagnostic process, how to leverage discoveries in pathophysiology into biomarkers, and how to develop an evidence base for current and novel treatments. These challenges are made greater by the realization of the wide spectrum of symptoms and difficulties faced by people with dystonia, which go well-beyond motor symptoms. A network of clinicians, scientists, and patients could provide resources to facilitate information exchange at different levels, share mutual experiences, and support each other's innovative projects. In the past, collaborative initiatives have been launched, including the American Dystonia Coalition, the European Cooperation in Science and Technology (COST-which however only existed for a limited time), and the Dutch DystonieNet project. The European Reference Network on Rare Neurological Diseases includes dystonia among other rare conditions affecting the central nervous system in a dedicated stream. Currently, we aim to broaden the scope of these initiatives to a comprehensive European level by further expanding the DystoniaNet network, in close collaboration with the ERN-RND. In line with the ERN-RND, the mission of DystoniaNet Europe is to improve care and quality of life for people with dystonia by, among other endeavors, facilitating access to specialized care, overcoming the disparity in education of medical professionals, and serving as a solid platform to foster international clinical and research collaborations. In this review, both professionals within the dystonia field and patients and caregivers representing Dystonia Europe highlight important unsolved issues and promising new strategies and the role that a European network can play in activating them.

Deep brain stimulation: Challenges at the tissue-electrode interface and current solutions

Deep brain stimulation (DBS) is used to treat the motor symptoms of Parkinson's disease patients by stimulating the subthalamic nucleus. However, optimization of DBS is still needed since the performance of the neural electrodes is limited by the body's response to the implant. This review discusses the issues with DBS, such as placement of electrodes, foreign body response, and electrode degradation. The current solutions to these technical issues include modifications to electrode material, coatings, and geometry.

A practical guide to troubleshooting pallidal deep brain stimulation issues in patients with dystonia

High frequency deep brain stimulation (DBS) of the internal portion of the globus pallidus has, in the last two decades, become a mainstream therapy for the management of medically-refractory dystonia syndromes. Such increasing uptake places an onus on movement disorder physicians to become familiar with this treatment modality, in particular optimal patient selection for the procedure and how to troubleshoot problems relating to sub-optimal efficacy and therapy-related side effects. Deep brain stimulation for dystonic conditions presents some unique challenges. For example, the frequent lack of immediate change in clinical status following stimulation alterations means that programming often relies on personal experience and local practice rather than real-time indicators of efficacy. Further, dystonia is a highly heterogeneous disorder, making the development of unifying guidelines and programming algorithms for DBS in this population difficult. Consequently, physicians may feel less confident in managing DBS for dystonia as compared to other indications e.g. Parkinson's disease. In this review, we integrate our years of personal experience of the programming of DBS systems for dystonia with a critical appraisal of the literature to produce a practical guide for troubleshooting common issues encountered in patients with dystonia treated with DBS, in the hope of improving the care for these patients.

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.

Postoperative Externalization of Deep Brain Stimulation Leads Does Not Increase Infection Risk

OBJECTIVES

Externalization of deep brain stimulation (DBS) leads is performed to allow electrophysiological recording from implanted electrodes as well as assessment of clinical response to trial stimulation before implantable pulse generator (IPG) insertion. Hypothetically, lead externalization provides a route for inoculation and subsequent infection of hardware, though this has not been established definitively in the literature. We sought to determine if lead externalization affects the risk of infection in DBS surgery.

MATERIALS AND METHODS

We present our center's experience of lead externalization and surgical site infection (SSI) in DBS surgery for movement disorders. Patients were divided into two cohorts: one in which leads were not externalized and IPGs were implanted at the time of electrode insertion, and one in which leads were externalized for six days while patients underwent electrophysiological recording from DBS electrodes for research. We compare baseline characteristics of these two cohorts and their SSI rates.

RESULTS

Infective complications were experienced by 3/82 (3.7%) patients overall with one (1.2%) requiring complete hardware removal. These occurred in 1/36 (2.7%) in the externalized cohort and 2/46 (4.3%) in the nonexternalized cohort. The incidence of infection between the two cohorts was not significantly different (p = 1, two-tailed Fisher's exact test). This lack of significant difference persisted when baseline variation between the cohorts in age, hardware manufacturer, and indication for DBS were corrected by excluding patients implanted for dystonia, none of whom underwent externalization. We present and discuss in detail each of the three cases of infection.

CONCLUSIONS

Our data suggest that externalization of leads does not increase the risk of infective complications in DBS surgery. Lead externalization is a safe procedure which can provide a substrate for unique neurophysiological studies to advance knowledge and therapy of disorders treated with DBS.

Pediatric Deep Brain Stimulation for Dystonia: Current State and Ethical Considerations

Dystonia is a movement disorder that can have a debilitating impact on motor functions and quality of life. There are 250,000 cases in the United States, most with childhood onset. Due to the limited effectiveness and side effects of available treatments, pediatric deep brain stimulation (pDBS) has emerged as an intervention for refractory dystonia. However, there is limited clinical and neuroethics research in this area of clinical practice. This paper examines whether it is ethically justified to offer pDBS to children with refractory dystonia. Given the favorable risk-benefit profile, it is concluded that offering pDBS is ethically justified for certain etiologies of dystonia, but it is less clear for others. In addition, various ethical and policy concerns are discussed, which need to be addressed to optimize the practice of offering pDBS for dystonia. Strategies are proposed to help address these concerns as pDBS continues to expand.

Application of Machine Learning Using Decision Trees for Prognosis of Deep Brain Stimulation of Globus Pallidus Internus for Children With Dystonia

BACKGROUND

While Deep Brain Stimulation (DBS) of the Globus pallidus internus is a well-established therapy for idiopathic/genetic dystonia, benefits for acquired dystonia are varied, ranging from modest improvement to deterioration. Predictive biomarkers to aid DBS prognosis for children are lacking, especially in acquired dystonias, such as dystonic Cerebral Palsy. We explored the potential role of machine learning techniques to identify parameters that could help predict DBS outcome.

METHODS

We conducted a retrospective study of 244 children attending King's College Hospital between September 2007 and June 2018 for neurophysiological tests as part of their assessment for possible DBS at Evelina London Children's Hospital. For the 133 individuals who underwent DBS and had 1-year outcome data available, we assessed the potential predictive value of six patient parameters: sex, etiology (including cerebral palsy), baseline severity (Burke-Fahn-Marsden Dystonia Rating Scale-motor score), cranial MRI and two neurophysiological tests, Central Motor Conduction Time (CMCT) and Somatosensory Evoked Potential (SEP). We applied machine learning analysis to determine the best combination of these features to aid DBS prognosis. We developed a classification algorithm based on Decision Trees (DTs) with k-fold cross validation for independent testing. We analyzed all possible combinations of the six features and focused on acquired dystonias.

RESULTS

Several trees resulted in better accuracy than the majority class classifier. However, the two features that consistently appeared in top 10 DTs were CMCT and baseline dystonia severity. A decision tree based on CMCT and baseline severity provided a range of sensitivity and specificity, depending on the threshold chosen for baseline dystonia severity. In situations where CMCT was not available, a DT using SEP alone provided better than the majority class classifier accuracy.

CONCLUSION

The results suggest that neurophysiological parameters can help predict DBS outcomes, and DTs provide a data-driven, highly interpretable decision support tool that lends itself to being used in clinical practice to help predict potential benefit of DBS in dystonic children. Our results encourage the introduction of neurophysiological parameters in assessment pathways, and data collection to facilitate multi-center evaluation and validation of these potential predictive markers and of the illustrative decision support tools presented here.

Deep Brain Stimulation of the Internal Pallidum in Lesch-Nyhan Syndrome: Clinical Outcomes and Connectivity Analysis

BACKGROUND

Lesch-Nyhan syndrome (LNS) is a rare genetic disorder characterized by a deficiency of hypoxanthine-guanine phosphoribosyltransferase enzyme. It manifests during infancy with compulsive self-mutilation behavior associated with disabling generalized dystonia and dyskinesia. Clinical management of these patients poses an enormous challenge for medical teams and carers.

OBJECTIVES

We report our experience with bilateral deep brain stimulation (DBS) of the globus pallidus internus (GPi) in the management of this complex disorder.

MATERIALS AND METHODS

Preoperative and postoperative functional assessment data prospectively collected by a multidisciplinary pediatric complex motor disorders team, including imaging, neuropsychology, and neurophysiology evaluations were analyzed with regards to motor and behavioral control, goal achievement, and patient and caregivers' expectations.

RESULTS

Four male patients (mean age 13 years) underwent DBS implantation between 2011 and 2018. Three patients received double bilateral DBS electrodes within the posteroventral GPi and the anteromedial GPi, whereas one patient had bilateral electrodes placed in the posteroventral GPi only. Median follow-up was 47.5 months (range 22-98 months). Functional improvement was observed in all patients and discussed in relation to previous reports. Analysis of structural connectivity revealed significant correlation between the involvement of specific cortical regions and clinical outcome.

CONCLUSION

Combined bilateral stimulation of the anteromedial and posteroventral GPi may be considered as an option for managing refractory dystonia and self-harm behavior in LNS patients. A multidisciplinary team-based approach is essential for patient selection and management, to support children and families, to achieve functional improvement and alleviate the overall disease burden for patients and caregivers.

Long term perceptions of illness and self after Deep Brain Stimulation in pediatric dystonia: A narrative research

BACKGROUND

Deep Brain Stimulation (DBS) is increasingly used in pediatric patients affected by isolated dystonia, with excellent results. Despite well documented long-term effects on motor functioning, information on quality of life and social adaptation is almost lacking.

OBJECTIVES

The present study aims to explore the experience of illness and the relation with the device in adult patients suffering from dystonia who underwent DBS surgery in pediatric age.

METHODS

A narrative inquiry approach was used to collect patients' narratives of their experience with dystonia and DBS stimulator. A written interview was administered to 8 patients over 18 years old with generalized isolated dystonia who had undergone pallidal DBS implantation in childhood. A thematic analysis was realized to examine the narratives collected.

RESULTS

Five main themes emerged: "relationship with the disease", "experience related to DBS procedure", "relationship with one's own body", "fears", "thoughts about future". Despite a general satisfaction in relation to DBS intervention, some patients expressed difficulties, such as the acceptance of changes in one's own body, concerns and fears regarding the device and the future, also considering the critical phase of transition from childhood to adulthood.

CONCLUSIONS

These results suggest that further research is needed to understand the contribution of psychological, as much as medical, aspects to the overall outcome of the intervention. The present explorative study encourages a deeper investigations of psychological aspects of patients, in order to plan a tailored care path and to decide whether to suggest a psychological support, both before and after the intervention.

Antibiotic Impregnated Catheter Coating Technique for Deep Brain Stimulation Hardware Infection: An Effective Method to Avoid Intracranial Lead Removal

BACKGROUND

Few studies have proposed alternative salvage methods of deep brain stimulation (DBS) intracranial lead once the infection has already occurred.

OBJECTIVE

To assess the effectiveness of antibiotic impregnated catheter coverage of DBS leads in case of hardware infection.

METHODS

Patients with a hardware infection and consequent partial removal of extension and internal pulse generator (IPG) were reviewed. To diagnose an infection, criteria provided by the Guideline for Prevention of Surgical Site Infection were used. We compared the intracranial lead salvage rate between the group that underwent antibiotic catheter lead protection (group A) and the group that did not (group B).

RESULTS

A total of 231 DBS surgeries and 339 IPG replacements were performed from January 2012 to January 2017. Twenty-three hardware-related infections (4%) were identified. Nineteen patients (82.6%) underwent partial hardware removal with an attempt to spare intracranial lead. Of these, 8 patients (42.1%) had antibiotic catheter lead coverage (group A) while 11 patients (57.9%) did not receive any antibiotic protection (group B). At 6-mo follow-up, 6 patients had the extension and IPG successfully re-implanted in group A, whereas only 1 patient was successfully re-implanted in group B (75 vs 9.1%; P < .001).

CONCLUSION

The antibiotic impregnated catheter coating technique seems to be effective in avoiding intracranial lead removal in case of IPG or DBS extension-lead junction infection. This method does not require any surgical learning curve, it is safe and relatively inexpensive. Randomized, prospective, larger studies are needed to validate our results.

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

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

Evaluation of neurosurgical implant infection rates and associated pathogens: evidence from 1118 postoperative infections

OBJECTIVE

Various implanted materials are used in neurosurgery; however, there remains a lack of pooled data on infection rates (IRs) and infective bacteria over past decades. The goal of this study was to investigate implant infections in neurosurgical procedures in a longitudinal retrospective study and to evaluate the IRs of neurosurgically implanted materials and the distribution of pathogenic microorganisms.

METHODS

A systematic literature search was conducted using PubMed and Web of Science databases for the time period between 1968 and 2018. Neurosurgical implant infections were studied in 5 subgroups, including operations or diseases, implanted materials, bacteria, distribution by country, and time periods, which were obtained from the literature and statistically analyzed. In this meta-analysis, statistical heterogeneity across studies was tested by using p values and I2 values between studies of associated pathogens. Egger’s test was used for assessing symmetries of funnel plots with Stata 11.0 software. Methodological quality was assessed to judge the risk of bias according to the Cochrane Handbook.

RESULTS

A total of 22,971 patients from 227 articles satisfied the study’s eligibility criteria. Of these, 1118 cases of infection were reported, and the overall IR was 4.87%. In this study, the neurosurgical procedures or disorders with the top 3 IRs included craniotomy (IR 6.58%), cranioplasty (IR 5.89%), and motor movement disorders (IR 5.43%). Among 13 implanted materials, the implants with the top 3 IRs included polypropylene-polyester, titanium, and polyetheretherketone (PEEK), which were 8.11%, 8.15%, and 7.31%, respectively. Furthermore, the main causative pathogen was Staphylococcus aureus and the countries with the top 3 IRs were Denmark (IR 11.90%), Korea (IR 10.98%), and Mexico (IR 9.26%). Except for the low IR from 1998 to 2007, the overall implant IR after neurosurgical procedures was on the rise.

CONCLUSIONS

In this study, the main pathogen in neurosurgery was S. aureus, which can provide a certain reference for the clinic. In addition, the IRs of polypropylene-polyester, titanium, and PEEK were higher than other materials, which means that more attention should be paid to them. In short, the total IR was high in neurosurgical implants and should be taken seriously.