Deep Brain Stimulation Target Selection for Parkinson’s Disease

Deep brain stimulation in Parkinson's disease: Looking back, looking forward

Patients with Parkinson’s disease (PD) may present with prodromal (e.g. hyposmia, sleep disorders, constipation), motor (e.g. tremors, rigidity, bradykinesia, postural dysfunction) and non-motor (e.g. cognitive dysfunction, depression) symptoms.1 Treatment is symptomatic, targeting motor and non-motor manifestations, but there is presently no effective disease modifying treatment.1 Although PD therapies have primarily been focused on supplementing dopamine, which has improved survival and quality of life of PD patients,1-3 other neurotransmitter systems (e.g. serotonergic, cholinergic and noradrenergic) are also dysfunctional, especially for the non-motor symptoms.1,4,5 By the time patients reach the later stages of PD, many of them would have developed significant gait and balance difficulties, dysarthria, dysphagia and motor fluctuations like wearing off and levodopa-induced dyskinesias (LID), as well as non-motor symptoms such as orthostasis, depression, dementia and psychosis.1,2,6,7

High frequency electrical stimulation reduces α-synuclein levels and α-synuclein-mediated autophagy dysfunction

Accumulation of α-synuclein (α-Syn) has been implicated in proteasome and autophagy dysfunction in Parkinson's disease (PD). High frequency electrical stimulation (HFS) mimicking clinical parameters used for deep brain stimulation (DBS) in vitro or DBS in vivo in preclinical models of PD have been found to reduce levels of α-Syn and, in certain cases, provide possible neuroprotection. However, the mechanisms by which this reduction in α-Syn improves cellular dysfunction associated with α-Syn accumulation remains elusive. Using HFS parameters that recapitulate DBS in vitro, we found that HFS led to a reduction of mutant α-Syn and thereby limited proteasome and autophagy impairments due to α-Syn. Additionally, we observed that HFS modulates via the ATP6V0C subunit of V-ATPase and mitigates α-Syn mediated autophagic dysfunction. This study highlights a role for autophagy in reduction of α-Syn due to HFS which may prove to be a viable approach to decrease pathological protein accumulation in neurodegeneration.

Advanced therapies in Parkinson's disease: an individualized approach to their indication

Device aided therapies (DAT) comprising the intrajejunal administration of levodopa/carbidopa intestinal gel (LCIG) and levodopa/carbidopa/entacapone intestinal gel (LECIG), the continuous subcutaneous application of foslevodopa/foscarbidopa or apomorphine infusion (CSAI) and deep brain stimulation (DBS) are used to treat Parkinson's disease with insufficient symptom alleviation under intensified pharmacotherapy. These DAT significantly differ in their efficacy profiles, indication, invasiveness, contraindications, and potential side effects. Usually, the evaluation of all these procedures is conducted simultaneously at the same point in time. However, as disease progression and symptom burden is extremely heterogeneous, clinical experience shows that patients reach the individual milestones for a certain therapy at different points in their disease course. Therefore, advocating for an individualized therapy evaluation for each DAT, requiring an ongoing evaluation. This necessitates that, during each consultation, the current symptomatology should be analyzed, and the potential suitability for a DAT be assessed. This work represents a critical interdisciplinary appraisal of these therapies in terms of their individual profiles and compares these DAT regarding contraindications, periprocedural considerations as well as their efficacy regarding motor- and non-motor deficits, supporting a personalized approach.

Successful asymmetrical deep brain stimulation using right subthalamic and left pallidal electrodes in a patient with Parkinson's disease

PURPOSE

Despite the best efforts of neurologists, the results of pharmacotherapy in the late stages of Parkinson's disease are often disappointing and accompanied by debilitating side effects. Under these circumstances, deep brain stimulation is a viable treatment option. The aim of the meticulous pre-surgical planning is not only precise electrode implantation, but also the avoidance of intraoperative vascular conflicts potentially causing intracerebral bleeding.

MATERIAL AND METHODS

In this report, we present a patient with early-onset Parkinson's disease whose cerebral vascular anatomy precluded standard bilateral subthalamic nucleus electrode implantation. Initially, right subthalamic stimulation alone provided a very mild clinical benefit that was not reflected in the patient's quality of life. In this patient, an unusual configuration of intracerebral electrodes with right subthalamic and left pallidal stimulation electrodes was applied 15 months after the initial subthalamic electrode implantation.

RESULTS

The procedure has had a highly beneficial long-term effect without any significant complications. The greatest improvement was noted using the setting 1.8 V, 130 Hz, 90 μs at the right side (STN) and 3.7 V, 130 Hz, 120 μs at the left side (GPi). This allowed the patient to return to his daily life activities.

CONCLUSIONS

The reported case provides a new perspective of treatment possibilities in complex functional neurosurgical cases requiring exceptional individualisation of the treatment approach.

Reduction of alpha-synuclein oligomers in preclinical models of Parkinson's disease by electrical stimulation in vitro and deep brain stimulation in vivo

BACKGROUND

Deep brain stimulation (DBS) has been widely used to manage debilitating neurological symptoms in movement disorders such as Parkinson's disease (PD). Despite its well-established symptomatic benefits, our understanding of the mechanisms underlying DBS and its possible effect on the accumulation of pathological proteins in neurodegeneration remains limited. Accumulation and oligomerization of the protein alpha-synuclein (α-Syn) are implicated in the loss of dopaminergic neurons in the substantia nigra in PD, making α-Syn a potential therapeutic target for disease modification.

OBJECTIVE

We examined the effects of high frequency electrical stimulation on α-Syn levels and oligomerization in cell and rodent models.

METHODS

High frequency stimulation, mimicking DBS parameters used for PD, was combined with viral-mediated overexpression of α-Syn in cultured rat primary cortical neurons or in substantia nigra of rats. Bimolecular protein complementation with split fluorescent protein reporters was used to detect and quantify α-Syn oligomers.

RESULTS

High frequency electrical stimulation reduced the expression of PD-associated mutant α-Syn and mitigated α-Syn oligomerization in cultured neurons. Furthermore, DBS in the substantia nigra, but not the subthalamic nucleus, decreased overall levels of α-Syn, including oligomer levels, in the substantia nigra.

CONCLUSIONS

Taken together, our results demonstrate that direct high frequency stimulation can reduce accumulation and pathological forms of α-Syn in cultured neurons in vitro and in substantia nigra in vivo. Thus, DBS therapy could have a role beyond symptomatic treatment, with potential disease-modifying properties that can be exploited to target pathological proteins in neurodegenerative diseases.

[Tremor-dominant form of Parkinson's disease]

The article is of a review nature and is devoted to tremor, one of the maladaptive and difficult-to-treat symptoms of Parkinson's disease (PD). Along with the classic rest tremor, patients with PD may experience tremor of other modalities: postural tremor, kinetic tremor, which reflects a multimodal mechanism of tremor formation involving multiple neurotransmitter systems. The unpredictable response to therapeutic options, the ambiguous response to levodopa, also reflects the role of multiple underlying pathophysiological processes. Among the drug methods of tremor correction, preference is given to dopamine receptor agonists - due to the spectrum of their pharmaceutical action, high efficiency in relation to all leading motor and a number of non-motor manifestations. The evidence for advanced neurosurgical, non-invasive modalities is mixed, and there are insufficient comparative studies to assess their efficacy in patients with tremor-dominant forms of PD.

Deep brain stimulation of globus pallidus internus and subthalamic nucleus in Parkinson's disease: a multicenter, retrospective study of efficacy and safety

BACKGROUND

Deep brain stimulation (DBS) is an established therapeutic option in advanced Parkinson's disease (PD). Literature data and recent guidelines remain inconclusive about the best choice as a target between the subthalamic nucleus (STN) and the globus pallidus internus (GPi).

MATERIALS AND METHODS

We retrospectively reviewed the clinical efficacy outcomes of 48 DBS-implanted patients (33 STN-DBS and 15 GPi-DBS) at a short- (<1 year from the surgery) and long-term (2-5 years) follow-up. Also, clinical safety outcomes, including postoperative surgical complications and severe side effects, were collected.

RESULTS

We found no difference between STN-DBS and GPi-DBS in improving motor symptoms at short-term evaluation. However, STN-DBS achieved a more prominent reduction in oral therapy (L-DOPA equivalent daily dose, P = .02). By contrast, GPi-DBS was superior in ameliorating motor fluctuations and dyskinesia (MDS-UPDRS IV, P < .001) as well as motor experiences of daily living (MDS-UPDRS II, P = .03). The greater efficacy of GPi-DBS on motor fluctuations and experiences of daily living was also present at the long-term follow-up. We observed five serious adverse events, including two suicides, all among STN-DBS patients.

CONCLUSION

Both STN-DBS and GPi-DBS are effective in improving motor symptoms severity and complications, but GPi-DBS has a greater impact on motor fluctuations and motor experiences of daily living. These results suggest that the two targets should be considered equivalent in motor efficacy, with GPi-DBS as a valuable option in patients with prominent motor complications. The occurrence of suicides in STN-treated patients claims further attention in target selection.

Neuronal and synaptic adaptations underlying the benefits of deep brain stimulation for Parkinson's disease

Deep brain stimulation (DBS) is a well-established and effective treatment for patients with advanced Parkinson's disease (PD), yet its underlying mechanisms remain enigmatic. Optogenetics, primarily conducted in animal models, provides a unique approach that allows cell type- and projection-specific modulation that mirrors the frequency-dependent stimulus effects of DBS. Opto-DBS research in animal models plays a pivotal role in unraveling the neuronal and synaptic adaptations that contribute to the efficacy of DBS in PD treatment. DBS-induced neuronal responses rely on a complex interplay between the distributions of presynaptic inputs, frequency-dependent synaptic depression, and the intrinsic excitability of postsynaptic neurons. This orchestration leads to conversion of firing patterns, enabling both antidromic and orthodromic modulation of neural circuits. Understanding these mechanisms is vital for decoding position- and programming-dependent effects of DBS. Furthermore, patterned stimulation is emerging as a promising strategy yielding long-lasting therapeutic benefits. Research on the neuronal and synaptic adaptations to DBS may pave the way for the development of more enduring and precise modulation patterns. Advanced technologies, such as adaptive DBS or directional electrodes, can also be integrated for circuit-specific neuromodulation. These insights hold the potential to greatly improve the effectiveness of DBS and advance PD treatment to new levels.

Closed-Loop Adaptive Deep Brain Stimulation in Parkinson's Disease: Procedures to Achieve It and Future Perspectives

Parkinson's disease (PD) is a neurodegenerative disease with a heavy burden on patients, families, and society. Deep brain stimulation (DBS) can improve the symptoms of PD patients for whom medication is insufficient. However, current open-loop uninterrupted conventional DBS (cDBS) has inherent limitations, such as adverse effects, rapid battery consumption, and a need for frequent parameter adjustment. To overcome these shortcomings, adaptive DBS (aDBS) was proposed to provide responsive optimized stimulation for PD. This topic has attracted scientific interest, and a growing body of preclinical and clinical evidence has shown its benefits. However, both achievements and challenges have emerged in this novel field. To date, only limited reviews comprehensively analyzed the full framework and procedures for aDBS implementation. Herein, we review current preclinical and clinical data on aDBS for PD to discuss the full procedures for its achievement and to provide future perspectives on this treatment.

Surgical Management of Synucleinopathies

Synucleinopathies represent a diverse set of pathologies with significant morbidity and mortality. In this review, we highlight the surgical management of three synucleinopathies: Parkinson’s disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). After examining underlying molecular mechanisms and the medical management of these diseases, we explore the role of deep brain stimulation (DBS) in the treatment of synuclein pathophysiology. Further, we examine the utility of focused ultrasound (FUS) in the treatment of synucleinopathies such as PD, including its role in blood–brain barrier (BBB) opening for the delivery of novel drug therapeutics and gene therapy vectors. We also discuss other recent advances in the surgical management of MSA and DLB. Together, we give a diverse overview of current techniques in the neurosurgical management of these pathologies.

Tremor in Parkinson's Disease: From Pathophysiology to Advanced Therapies

Background

Tremor is one of the most prevalent symptoms in Parkinson's Disease (PD). The progression and management of tremor in PD can be challenging, as response to dopaminergic agents might be relatively poor, particularly in patients with tremor-dominant PD compared to the akinetic/rigid subtype. In this review, we aim to highlight recent advances in the underlying pathogenesis and treatment modalities for tremor in PD.

Methods

A structured literature search through Embase was conducted using the terms "Parkinson's Disease" AND "tremor" OR "etiology" OR "management" OR "drug resistance" OR "therapy" OR "rehabilitation" OR "surgery." After initial screening, eligible articles were selected with a focus on published literature in the last 10 years.

Discussion

The underlying pathophysiology of tremor in PD remains complex and incompletely understood. Neurodegeneration of dopaminergic neurons in the retrorubral area, in addition to high-power neural oscillations in the cerebello-thalamo-cortical circuit and the basal ganglia, play a major role. Levodopa is the first-line therapeutic option for all motor symptoms, including tremor. The addition of dopamine agonists or anticholinergics can lead to further tremor reduction. Botulinum toxin injection is an effective alternative for patients with pharmacological-resistant tremor who are not seeking advanced therapies. Deep brain stimulation is the most well-established advanced therapy owing to its long-term efficacy, reversibility, and effectiveness in other motor symptoms and fluctuations. Magnetic resonance-guided focused ultrasound is a promising modality, which has the advantage of being incisionless. Cortical and peripheral electrical stimulation are non-invasive innovatory techniques that have demonstrated good efficacy in suppressing intractable tremor.

Initiating dopamine agonists rather than levodopa in early Parkinson's disease does not delay the need for deep brain stimulation

BACKGROUND

While levodopa is the most effective symptomatic treatment for Parkinson's disease (PD), its use is associated with an increased risk of motor complications (MC) in the first five years of treatment compared to dopamine agonist (DA) first therapy. It is not known whether this translates into true benefit later in the disease. We aimed to determine whether there is a difference in the time between initial levodopa vs DA treatment and the development of disabling MC prompting DBS consideration.

METHODS

This was a retrospective cohort study of PD patients attending the DBS Clinic at Toronto Western Hospital, Canada between 03/2004-02/2022 who underwent globus pallidus interna (GPi) or subthalamic nucleus (STN) DBS in 2005 or later for disabling MC.

RESULTS

Of 438 patients included, 352 patients underwent STN DBS, 86 GPi. The median disease duration was 9 years (2-30). The majority (n=312) received levodopa first and 126 a DA. There was no significant difference in the disease duration, or amantadine use between the two groups. The duration first treatment-assessment for DBS (L-dopa median 8, IQR 4; DA median 9, IQR 4) or DBS surgery (levodopa median 10, IQR 5; DA median 10, IQR 5), did not differ.

CONCLUSION

To our knowledge this is the only study to date to evaluate the duration between L-dopa/DA first treatment and the development of MC of sufficient severity to warrant consideration of DBS. No association was found. The results suggest that the development of disabling MC warranting DBS is independent of the type of first dopaminergic treatment.

Frontostriatal circuitry as a target for fMRI-based neurofeedback interventions: A systematic review

Dysregulated frontostriatal circuitries are viewed as a common target for the treatment of aberrant behaviors in various psychiatric and neurological disorders. Accordingly, experimental neurofeedback paradigms have been applied to modify the frontostriatal circuitry. The human frontostriatal circuitry is topographically and functionally organized into the "limbic," the "associative," and the "motor" subsystems underlying a variety of affective, cognitive, and motor functions. We conducted a systematic review of the literature regarding functional magnetic resonance imaging-based neurofeedback studies that targeted brain activations within the frontostriatal circuitry. Seventy-nine published studies were included in our survey. We assessed the efficacy of these studies in terms of imaging findings of neurofeedback intervention as well as behavioral and clinical outcomes. Furthermore, we evaluated whether the neurofeedback targets of the studies could be assigned to the identifiable frontostriatal subsystems. The majority of studies that targeted frontostriatal circuitry functions focused on the anterior cingulate cortex, the dorsolateral prefrontal cortex, and the supplementary motor area. Only a few studies (n = 14) targeted the connectivity of the frontostriatal regions. However, post-hoc analyses of connectivity changes were reported in more cases (n = 32). Neurofeedback has been frequently used to modify brain activations within the frontostriatal circuitry. Given the regulatory mechanisms within the closed loop of the frontostriatal circuitry, the connectivity-based neurofeedback paradigms should be primarily considered for modifications of this system. The anatomical and functional organization of the frontostriatal system needs to be considered in decisions pertaining to the neurofeedback targets.

Contracted thalamic shape is associated with early development of levodopa-induced dyskinesia in Parkinson's disease

Levodopa-induced dyskinesia (LID), a long-term motor complication in Parkinson’s disease (PD), is attributable to both presynaptic and postsynaptic mechanisms. However, no studies have evaluated the baseline structural changes associated with LID at a subcortical level in PD. A total of 116 right-handed PD patients were recruited and based on the LID latency of 5 years, we classified patients into those vulnerable to LID (PD-vLID, n = 49) and those resistant to LID (PD-rLID, n = 67). After adjusting for covariates including dopamine transporter (DAT) availability of the posterior putamen, we compared the subcortical shape between the groups and investigated its association with the onset of LID. The PD-vLID group had lower DAT availability in the posterior putamen, higher parkinsonian motor deficits, and faster increment in levodopa equivalent dose than the PD-rLID group. The PD-vLID group had significant inward deformation in the right thalamus compared to the PD-rLID group. Inward deformation in the thalamus was associated with an earlier onset of LID at baseline. This study suggests that independent of presynaptic dopamine depletion, the thalamus is a major neural substrate for LID and that a contracted thalamic shape at baseline is closely associated with an early development of LID.

Does Quantitative Electroencephalography Refine Preoperative Cognitive Assessment in Parkinson's Disease Patients Treated with Deep Brain Stimulation? A Follow-Up Study

OBJECTIVE

Deep brain stimulation (DBS) in Parkinson's disease (PD) is associated with an increased risk of post-operative cognitive deterioration. Preoperative neuropsychological testing can be affected and limited by the patient's collaboration in advanced disease. The purpose of this study was to determine whether preoperative quantitative electroencephalography (qEEG) may be a useful complementary examination technique during preoperative assessment to predict cognitive changes in PD patients treated with DBS.

METHODS

We compared the cognitive performance of 16 PD patients who underwent bilateral subthalamic nucleus DBS to the performance of 15 PD controls (matched for age, sex, and education) at baseline and at 24 months. Cognitive scores were calculated for all patients across 5 domains. A preoperative 256-channel resting EEG was recorded from each patient. We computed the global relative power spectra. Correlation and linear regression models were used to assess associations of preoperative EEG measures with post-operative cognitive scores.

RESULTS

Slow waves (relative delta and theta band power) were negatively correlated with post-operative cognitive performance, while faster waves (alpha 1) were strongly positively correlated with the same scores (the overall cognitive score, attention, and executive function). Linear models revealed an association of delta power with the overall cognitive score (p = 0.00409, adjusted R2 = 0.6341). Verbal fluency (VF) showed a significant decline after DBS surgery, which was correlated with qEEG measures.

CONCLUSIONS

To analyse the side effects after DBS in PD patients, the most important parameter is verbal fluency capacity. In addition, correlation with EEG frequency bands might be useful to detect particularly vulnerable patients for cognitive impairment and be supportive in the selection process of patients considered for DBS.

Axial Impairment Following Deep Brain Stimulation in Parkinson's Disease: A Surgicogenomic Approach

Background:

Postoperative outcome following deep brain stimulation (DBS) of the subthalamic nucleus is variable, particularly with respect to axial motor improvement. We hypothesized a genetic underpinning to the response to surgical intervention, termed “surgicogenomics”.

Objective:

We aimed to identify genetic variants associated with clinical heterogeneity in DBS outcome of Parkinson’s disease (PD) patients that could then be applied clinically to target selection leading to improved surgical outcome.

Methods:

Retrospective clinical data was extracted from 150 patient’s charts. Each individual was genotyped using the genome-wide NeuroX array tailored to study neurologic diseases. Genetic data were clustered based on surgical outcome assessed by comparing pre- and post-operative scores of levodopa equivalent daily dose and axial impairment at one and five years post-surgery. Allele frequencies were compared between patients with excellent vs. moderate/poor outcomes grouped using a priori defined cut-offs. We analyzed common variants, burden of rare coding variants, and PD polygenic risk score.

Results:

NeuroX identified 2,917 polymorphic markers at 113 genes mapped to known PD loci. The gene-burden analyses of 202 rare nonsynonymous variants suggested a nominal association of axial impairment with 14 genes (most consistent with CRHR1, IP6K2, and PRSS3). The strongest association with surgical outcome was detected between a reduction in levodopa equivalent daily dose and common variations tagging two linkage disequilibrium blocks with SH3GL2.

Conclusion:

Once validated in independent populations, our findings may be implemented to improve patient selection for DBS in PD.

Adaptive Parameter Modulation of Deep Brain Stimulation Based on Improved Supervisory Algorithm

Clinically deployed deep brain stimulation (DBS) for the treatment of Parkinson's disease operates in an open loop with fixed stimulation parameters, and this may result in high energy consumption and suboptimal therapy. The objective of this manuscript is to establish, through simulation in a computational model, a closed-loop control system that can automatically adjust the stimulation parameters to recover normal activity in model neurons. Exaggerated beta band activity is recognized as a hallmark of Parkinson's disease and beta band activity in model neurons of the globus pallidus internus (GPi) was used as the feedback signal to control DBS of the GPi. Traditional proportional controller and proportional-integral controller were not effective in eliminating the error between the target level of beta power and the beta power under Parkinsonian conditions. To overcome the difficulties in tuning the controller parameters and improve tracking performance in the case of changes in the plant, a supervisory control algorithm was implemented by introducing a Radial Basis Function (RBF) network to build the inverse model of the plant. Simulation results show the successful tracking of target beta power in the presence of changes in Parkinsonian state as well as during dynamic changes in the target level of beta power. Our computational study suggests the feasibility of the RBF network-driven supervisory control algorithm for real-time modulation of DBS parameters for the treatment of Parkinson's disease.

Deep Brain Stimulation of the Habenula: Systematic Review of the Literature and Clinical Trial Registries

The habenula is a small bilateral epithalamic structure that plays a key role in the regulation of the main monoaminergic systems. It is implicated in many aspects of behavior such as reward processing, motivational behavior, behavioral adaptation, and sensory integration. A role of the habenula has been indicated in the pathophysiology of a number of neuropsychiatric disorders such as depression, addiction, obsessive-compulsive disorder, and bipolar disorder. Neuromodulation of the habenula using deep brain stimulation (DBS) as potential treatment has been proposed and a first successful case of habenula DBS was reported a decade ago. To provide an overview of the current state of habenula DBS in human subjects for the treatment of neuropsychiatric disorders we conducted a systematic review of both the published literature using PUBMED and current and past registered clinical trials using ClinicalTrials.gov as well as the International Clinical Trials Registry Platform. Using PRISMA guidelines five articles and five registered clinical trials were identified. The published articles detailed the results of habenula DBS for the treatment of schizophrenia, depression, obsessive-compulsive disorder, and bipolar disorder. Four are single case studies; one reports findings in two patients and positive clinical outcome is described in five of the six patients. Of the five registered clinical trials identified, four investigate habenula DBS for the treatment of depression and one for obsessive-compulsive disorder. One trial is listed as terminated, one is recruiting, two are not yet recruiting and the status of the fifth is unknown. The planned enrollment varies between 2 to 13 subjects and four of the five are open label trials. While the published studies suggest a potential role of habenula DBS for a number of indications, future trials and studies are necessary. The outcomes of the ongoing clinical trials will provide further valuable insights. Establishing habenula DBS, however, will depend on successful randomized clinical trials to confirm application and clinical benefit of this promising intervention.

Dissociative Tremor Response with Pallidal Deep Brain Stimulation in Parkinson's Disease

Background:

Pallidal and subthalamic targets are commonly used for deep brain stimulation in Parkinson’s disease (PD), with similar efficacy for resting tremor control. However, neuromodulatory effects on kinetic and postural tremor in PD is less clear.

Case Report:

We present a 67-year-old PD patient with marked dissociative tremor response following pallidal neuromodulation. We observed excellent resting tremor suppression, but postural and kinetic tremors remained severe, requiring additional thalamic VIM stimulation for management.

Discussion:

Our findings illustrate the phenotypical differences in PD and differential response to diverse tremor characteristics with distinctive stimulation targets. Additional studies are necessary to understand these differences.

Deep brain stimulation electrode position impact on parkinsonian non-motor symptoms

BACKGROUND

In this study we evaluated the impact of location of deep brain stimulation electrode active contact in different parts of the subthalamic nucleus on improvement of non-motor symptoms in patients with Parkinson's disease.

METHODS

The subthalamic nucleus was divided into two (dorsolateral/ventromedial) and three (dorsolateral, medial, ventromedial) parts. 37 deep brain stimulation electrodes were divided according to their active contact location. Correlation between change in non-motor symptoms before and one and four months after deep brain stimulation electrode implantation and the location of active contact was made.

RESULTS

In dividing the subthalamic nucleus into three parts, no electrode active contact was placed ventromedially, 28 active contacts were located in the medial part and 9 contacts were placed dorsolaterally. After one and four months, no significant difference was found between medial and dorsolateral positions. In the division of the subthalamic nucleus into two parts, 13 contacts were located in the ventromedial part and 24 contacts were placed in the dorsolateral part. After one month, significantly greater improvement in the Non-motor Symptoms Scale for Parkinson's disease (P=0.045) was found on dorsolateral left-sided stimulation, but no significant differences between the ventromedial and dorsolateral positions were found on the right side.

CONCLUSION

This study demonstrated the relationship between improvement of non-motor symptoms and the side (hemisphere, left/right) of the deep brain stimulation electrode active contact, rather than its precise location within specific parts of the subthalamic nucleus in patients treated for advanced Parkinson's disease.

Before and after the veterans affairs cooperative program 468 study: Deep brain stimulator target selection for treatment of Parkinson's disease

INTRODUCTION

The Veterans Affairs Cooperative Study Program 468 study (CSP 468) produced significant findings regarding deep brain stimulation (DBS) target selection for Parkinson's Disease (PD) treatment, yet its impact on clinical practices has not been described. Here we assess how CSP 468 influenced target selection at a high-volume movement disorders treatment center.

METHODS

We compared DBS target site selection between 4-year periods that immediately preceded and followed CSP 468 publication. Additionally, we examined how baseline clinical features influenced target selection following CSP 468.

RESULTS

The STN was the predominant site of DBS implantation before and after CSP 468 publication (93.2% of cases, and 60.4%, respectively), but GPi targeting increased significantly following CSP 468 publication (from 5.3% to 37.4%; p < .001). Patients who underwent GPi stimulation following CSP 468 exhibited worse indices of depression (p < .001), less responsiveness to medications (p < .05), and a trend towards worse pre-operative cognitive performance (p = .06). In multi-variate analysis, advanced patient age and depression were independent predictors of GPi targeting (p < .01).

CONCLUSIONS

Key findings of CSP 468 were reflected in our target selection of DBS for Parkinson's Disease. Following CSP 468, GPi targeting increased, and it was selected for patients with poorer cognitive and mood indices.

Older Candidates for Subthalamic Deep Brain Stimulation in Parkinson's Disease Have a Higher Incidence of Psychiatric Serious Adverse Events

Objective: To investigate the incidence of serious adverse events (SAE) of subthalamic deep brain stimulation (STN-DBS) in elderly patients with Parkinson's disease (PD).

Methods: We investigated a group of 26 patients with PD who underwent STN-DBS at mean age 63.2 ± 3.3 years. The operated patients from the EARLYSTIM study (mean age 52.9 ± 6.6) were used as a comparison group. Incidences of SAE were compared between these groups.

Results: A higher incidence of psychosis and hallucinations was found in these elderly patients compared to the younger patients in the EARLYSTIM study (p < 0.01).

Conclusions: The higher incidence of STN-DBS-related psychiatric complications underscores the need for comprehensive psychiatric pre- and postoperative assessment in older DBS candidates. However, these psychiatric SAE were transient, and the benefits of DBS clearly outweighed its adverse effects.