Persistent adverse effects following different targets and periods after bilateral deep brain stimulation in patients with Parkinson's disease

Role of the globus pallidus in motor and non-motor symptoms of Parkinson's disease

The globus pallidus plays a pivotal role in the basal ganglia circuit. Parkinson's disease is characterized by degeneration of dopamine-producing cells in the substantia nigra, which leads to dopamine deficiency in the brain that subsequently manifests as various motor and non-motor symptoms. This review aims to summarize the involvement of the globus pallidus in both motor and non-motor manifestations of Parkinson's disease. The firing activities of parvalbumin neurons in the medial globus pallidus, including both the firing rate and pattern, exhibit strong correlations with the bradykinesia and rigidity associated with Parkinson's disease. Increased beta oscillations, which are highly correlated with bradykinesia and rigidity, are regulated by the lateral globus pallidus. Furthermore, bradykinesia and rigidity are strongly linked to the loss of dopaminergic projections within the cortical-basal ganglia-thalamocortical loop. Resting tremors are attributed to the transmission of pathological signals from the basal ganglia through the motor cortex to the cerebellum-ventral intermediate nucleus circuit. The cortico-striato-pallidal loop is responsible for mediating pallidi-associated sleep disorders. Medication and deep brain stimulation are the primary therapeutic strategies addressing the globus pallidus in Parkinson's disease. Medication is the primary treatment for motor symptoms in the early stages of Parkinson's disease, while deep brain stimulation has been clinically proven to be effective in alleviating symptoms in patients with advanced Parkinson's disease, particularly for the movement disorders caused by levodopa. Deep brain stimulation targeting the globus pallidus internus can improve motor function in patients with tremor-dominant and non-tremor-dominant Parkinson's disease, while deep brain stimulation targeting the globus pallidus externus can alter the temporal pattern of neural activity throughout the basal ganglia-thalamus network. Therefore, the composition of the globus pallidus neurons, the neurotransmitters that act on them, their electrical activity, and the neural circuits they form can guide the search for new multi-target drugs to treat Parkinson's disease in clinical practice. Examining the potential intra-nuclear and neural circuit mechanisms of deep brain stimulation associated with the globus pallidus can facilitate the management of both motor and non-motor symptoms while minimizing the side effects caused by deep brain stimulation.

Number of serotonergic neurons in the subthalamic nucleus and globus pallidus internus could influence the effects of deep brain stimulation in Parkinson's disease

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) or globus pallidus internus (GPi) is a standard treatment for Parkinson's disease (PD), with both regions exhibiting similar treatment effectiveness. However, posttreatment neuropsychiatric side effects, such as severe depression, are common, primarily due to the loss of serotonergic cells. Identifying a region with fewer serotonergic neurons could potentially reduce these side effects. This study aimed to quantify the number of serotonergic neurons in the STN and GPi. Both regions were analyzed using hematoxylin and eosin staining and immunohistochemistry. The GPi exhibited a significantly lower number and H-score of serotonergic neurons than the STN. Within the STN, the number and H-score of serotonergic neurons were higher in the medial aspect than in the lateral aspect. Three different types of neurons, large and small, were observed. In STN, large neurons were concentrated in the center and small neurons in the periphery. This distribution was not observed in GPi. In addition, the concentration of the serotonergic neurons is less in GPi. These findings suggest that the GPi may be a safer target region, potentially reducing the incidence of post-DBS depression.

Ultrasound Imaging Triggered Tremor Suppression With Personalized Afferent Stimulation Frequency

OBJECTIVE

Afferent stimulation of peripheral nerves has emerged as a non-invasive approach to suppress wrist tremors in persons with Essential Tremor (ET) and Parkinson' s disease (PD). Electromyography (EMG), a standard sensing modality for tremor characterization during afferent stimulation, has a significant drawback. Due to stimulation artifacts, measuring tremor frequency with EMG and applying stimulation simultaneously is often tricky. This paper investigates a stimulation artifact-free approach that uses real-time ultrasound (US) imaging-derived signals to cue afferent stimulation.

METHODS

We derived a real-time US imaging-based tissue displacement metric to characterize the wrist tremor in participants with PD or ET. We also compared the metric' s feasibility in detecting the wrist tremor with conventional sensors. We further determined an effective afferent stimulation frequency for each participant that achieved the best tremor suppression. Finally, the metric was evaluated to trigger afferent stimulation (on or off) on the onset or subsidence of the wrist tremor in four participants with PD or ET (two PD, two ET).

RESULTS

Ultrasound imaging can effectively measure the tremor frequency with no significant difference from gold-standard sensors such as EMG and IMU. The US metric-triggered personalized stimulation frequency achieved tremor suppression ratios ranging from 20-73 % in two PD and two ET participants.

CONCLUSION

These findings indicate that a stimulation artifact-free US-imaging-based metric can simultaneously measure individual tremor characteristics and trigger afferent stimulation.

SIGNIFICANCE

Our work lays the foundation for new US imaging-based, non-invasive afferent stimulation paradigms for tremor suppression that can potentially benefit more than 11 million people with ET and PD.

Motor outcomes in unilateral, bilateral rapid, and bilateral delayed staging deep brain stimulation for Parkinson's disease

BACKGROUND

Deep brain stimulation (DBS) is effective in managing motor symptoms in select cases of Parkinson's disease (PD). Nonetheless, the ideal timing for surgery and the comparative outcomes of unilateral versus bilateral DBS procedures remain under-researched areas.

OBJECTIVE

We aimed to compare the impact of unilateral and bilateral DBS on the motor manifestations of PD using standardized Unified Parkinson's Disease Rating Scale Part-III (UPDRS-III).

METHODS

We conducted a retrospective analysis of PD patients who underwent multidisciplinary DBS screening which made a formal recommendation for surgical approach. We compared unilateral, bilateral "rapid" (less than 2 months apart), and bilateral "staged" (5-11 months apart) implantation approaches. The study included 90 patients, 48 patients, and 42 patients from the 3 groups, respectively. The primary outcome was the percentage improvement in baseline off UPDRS-III scores compared to medication-off/DBS-on conditions at 3-6 months and 10-14 months post-surgery. Mann-Whitney U tests were used to compare scores within groups and across follow-up periods. The Kruskal-Wallis test assessed differences among groups. Furthermore, multiple regression analyses were performed to adjust for confounding variables.

RESULTS

UPDRS-III scores improved significantly from baseline at both follow-up intervals regardless of the type of DBS staging approach. The Kruskal-Wallis test revealed no significant differences in UPDRS-III percentage improvement among groups at 3-6 months (p = 0.125) and 10-14 months (p = 0.298) post-DBS.

CONCLUSIONS

Our study revealed that in a single experienced DBS center which employed multidisciplinary screening, assignment to unilateral and bilateral DBS, both rapid and staged, targeting the STN or GPi, effectively improved motor symptoms for up to 14 months.

Deep brain stimulation of symptom-specific networks in Parkinson's disease

Deep Brain Stimulation can improve tremor, bradykinesia, rigidity, and axial symptoms in patients with Parkinson's disease. Potentially, improving each symptom may require stimulation of different white matter tracts. Here, we study a large cohort of patients (N = 237 from five centers) to identify tracts associated with improvements in each of the four symptom domains. Tremor improvements were associated with stimulation of tracts connected to primary motor cortex and cerebellum. In contrast, axial symptoms are associated with stimulation of tracts connected to the supplementary motor cortex and brainstem. Bradykinesia and rigidity improvements are associated with the stimulation of tracts connected to the supplementary motor and premotor cortices, respectively. We introduce an algorithm that uses these symptom-response tracts to suggest optimal stimulation parameters for DBS based on individual patient's symptom profiles. Application of the algorithm illustrates that our symptom-tract library may bear potential in personalizing stimulation treatment based on the symptoms that are most burdensome in an individual patient.

The Effects of Deep Brain Stimulation on Speech Motor Control in People With Parkinson's Disease

PURPOSE

Despite the overall benefits of deep brain stimulation (DBS) in Parkinson's disease (PD), its effects on speech production have been mixed when examined using auditory-perceptual and acoustic measures. This study investigated the effects of DBS on the lip and jaw kinematics during sentence production in individuals with dysarthria secondary to PD.

METHOD

Twenty-seven participants from three groups were included in the study: (a) individuals with PD and without DBS (PD group), (b) individuals with PD and with DBS (PD-DBS group), and (c) neurologically healthy control speakers (HC group). Lip and jaw movements during speech were recorded using optical motion capture and analyzed for path distance, speed, duration, articulatory stability, and interarticulator coordination.

RESULTS

The PD-DBS group showed (a) increased path distance compared with the PD and HC groups and (b) increased speed compared with the PD group but not the HC group. Both PD and PD-DBS groups exhibited lengthened sentence duration compared with the HC group. Articulatory stability was greater for the two PD groups, PD and PD-DBS, compared with the HC group. Spatial, but not temporal, coordination was lower for the PD group than for the other two groups. The only kinematic changes between the DBS on and off conditions within the PD-DBS group were increases in spatial coordination.

CONCLUSIONS

These data suggest that DBS primarily affects the amplitude scaling of articulatory movements, but not the temporal scaling, in individuals with PD. The findings are discussed with respect to the DBS-induced neural changes and their effects on speech motor control in PD.

Computerized analysis of speech and voice for Parkinson's disease: A systematic review

BACKGROUND AND OBJECTIVE

Speech impairment is an early symptom of Parkinson's disease (PD). This study has summarized the literature related to speech and voice in detecting PD and assessing its severity.

METHODS

A systematic review of the literature from 2010 to 2021 to investigate analysis methods and signal features. The keywords "Automatic analysis" in conjunction with "PD speech" or "PD voice" were used, and the PubMed and ScienceDirect databases were searched. A total of 838 papers were found on the first run, of which 189 were selected. One hundred and forty-seven were found to be suitable for the review. The different datasets, recording protocols, signal analysis methods and features that were reported are listed. Values of the features that separate PD patients from healthy controls were tabulated. Finally, the barriers that limit the wide use of computerized speech analysis are discussed.

RESULTS

Speech and voice may be valuable markers for PD. However, large differences between the datasets make it difficult to compare different studies. In addition, speech analytic methods that are not informed by physiological understanding may alienate clinicians.

CONCLUSIONS

The potential usefulness of speech and voice for the detection and assessment of PD is confirmed by evidence from the classification and correlation results.

A Review on Response to Device-Aided Therapies Used in Monogenic Parkinsonism and GBA Variants Carriers: A Need for Guidelines and Comparative Studies

Parkinson's disease (PD) is in some cases predisposed-or-caused by genetic variants, contributing to the expression of different phenotypes. Regardless of etiology, as the disease progresses, motor fluctuations and/or levodopa-induced dyskinesias limit the benefit of pharmacotherapy. Device-aided therapies are good alternatives in advanced disease, including deep brain stimulation (DBS), levodopa-carbidopa intestinal gel, and continuous subcutaneous infusion of apomorphine. Candidate selection and timing are critical for the success of such therapies. Genetic screening in DBS cohorts has shown a higher proportion of mutation carriers than in general cohorts, suggesting that genetic factors may influence candidacy for advanced therapies. The response of monogenic PD to device therapies is not well established, and the contribution of genetic information to decision-making is still a matter of debate. The limited evidence regarding gene-dependent response to device-aided therapies is reviewed here. An accurate understanding of the adequacy and responses of different mutation carriers to device-aided therapies requires the development of specific studies with long-term monitoring.

Does Subthalamic Deep Brain Stimulation Impact Asymmetry and Dyscoordination of Gait in Parkinson's Disease?

Background. Subthalamic deep brain stimulation (STN-DBS) is an effective treatment for selected Parkinson's disease (PD) patients. Gait characteristics are often altered after surgery, but quantitative therapeutic effects are poorly described. Objective. The goal of this study was to systematically investigate modifications in asymmetry and dyscoordination of gait 6 months postoperatively in patients with PD and compare the outcomes with preoperative baseline and to asymptomatic controls without PD. Methods. A convenience sample of thirty-two patients with PD (19 with postural instability and gait disorder (PIGD) type and 13 with tremor dominant disease) and 51 asymptomatic controls participated. Parkinson patients were tested prior to the surgery in both OFF and ON medication states, and 6-months postoperatively in the ON stimulation condition. Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) I to IV and medication were compared to preoperative conditions. Asymmetry ratios, phase coordination index, and walking speed were assessed. Results. MDS-UPDRS I to IV at 6 months improved significantly, and levodopa equivalent daily dosages significantly decreased. STN-DBS increased step time asymmetry (hedges' g effect sizes [95% confidence interval] between pre- and post-surgery: .27 [-.13, .73]) and phase coordination index (.29 [-.08, .67]). These effects were higher in the PIGD subgroup than the tremor dominant (step time asymmetry: .38 [-.06, .90] vs .09 [-.83, 1.0] and phase coordination index: .39 [-.04, .84] vs .13 [-.76, .96]). Conclusions. This study provides objective evidence of how STN-DBS increases asymmetry and dyscoordination of gait in patients with PD and suggests motor subtypes-associated differences in the treatment response.

Should we start integrating genetic data in decision-making on device-aided therapies in Parkinson disease? A point of view

Parkinson disease (PD) is a complex heterogeneous neurodegenerative disorder. Association studies have revealed numerous genetic risk loci and variants, and about 5-10% suffer from a monogenic form. Because the presentation and course of PD is unique to each patient, personalized symptomatic treatment should ideally be offered to treat the most disabling motor and non-motor symptoms. Indeed, clinical milestones and treatment complications that appear during disease progression are influenced by the genetic imprint. With recent advances in PD, more patients live longer to become eligible for device-aided therapies, such as apomorphine continuous subcutaneous infusion, levodopa duodenal gel infusion, and deep brain stimulation surgery, each with its own inclusion and exclusion criteria, advantages and disadvantages. Because genetic variants influence the expression of particular clinical profiles, factors for better or worse outcomes for device-aided therapies may then be proactively identified. For example, mutations in PRKN, LRRK2 and GBA express phenotypes that favor suitability for different device therapies, although with marked differences in the therapeutic window; whereas multiplications of SNCA express phenotypes that make them less desirable for device therapies.

Gastrointestinal dysfunction in the synucleinopathies

Interest in gastrointestinal dysfunction in Parkinson's disease has blossomed over the past 30 years and has generated a wealth of investigation into this non-motor aspect of the disorder, research that has encompassed its pathophysiology, its clinical features, and its impact on quality of life. The question of gastrointestinal dysfunction in the other synucleinopathies has not received nearly as much attention, but information and knowledge are growing. In this review, the current knowledge, controversies, and gaps in our understanding of the pathophysiology of gastrointestinal dysfunction in Parkinson's disease and the other synucleinopathies will be addressed, and extended focus will be directed toward the clinical problems involving saliva management, swallowing, gastric emptying, small intestinal function, and bowel function that are so problematic in these disorders.

An individual patient analysis of the efficacy of using GPi-DBS to treat Huntington's disease

OBJECTIVE

The efficacy of globus pallidus internus-deep brain stimulation (GPi-DBS) for the treatment of Huntington's disease (HD) has not been validated in large-scale studies. We conducted an individual patient analysis to pool outcomes of all of the published HD-GPi-DBS studies.

METHODS

PubMed, Embase and the Cochrane Library were searched for relevant articles. The Unified Huntington's Disease Rating Scale (UHDRS)-motor and UHDRS-chorea improvements were analyzed during different follow-up periods. Secondary outcomes, including UHDRS-motor subitem scores and functional assessment results, were also analyzed. Correlation and regression analyses were conducted to find improvement predictors. This study was registered in PROSPERO (CRD42018105995).

RESULTS

Eighteen studies including 39 patients with 124 visits were analyzed. GPi-DBS significantly improved the UHDRS-motor score in <3 months (p = 0.001), 3-9 months (p < 0.001), and 9-12 months (p < 0.001), but did not continue in later follow-ups. UHDRS-chorea was significantly improved even in the >30-month follow-up (p = 0.003). Functional assessment was not improved 12 months postoperatively (p = 0.196). The Westphal variant of HD (W-HD) gained no motor benefits 6 months postoperatively (p = 0.178). The Westphal variant was the only risk factor for DBS efficacy (p = 0.044). The rate of stimulation-related adverse events was 87.2%.

CONCLUSIONS

GPi-DBS has a stable effect on chorea symptoms in HD patients. Chorea-dominant patients may be the best candidates for surgery, while attention should be paid to postoperative stimulation-related complications. Given that GPi-DBS has limited effects on other motor symptoms, W-HD patients are not surgical candidates.

Autonomic Dysfunction in Parkinson's Disease

Recognition of the importance of nonmotor dysfunction as a component of Parkinson's disease has exploded over the past three decades. Autonomic dysfunction is a frequent and particularly important nonmotor feature because of the broad clinical spectrum it covers. Cardiovascular, gastrointestinal, urinary, sexual, and thermoregulatory abnormalities all can appear in the setting of Parkinson's disease. Cardiovascular dysfunction is characterized most prominently by orthostatic hypotension. Gastrointestinal dysfunction can involve virtually all levels of the gastrointestinal tract. Urinary dysfunction can entail either too frequent voiding or difficulty voiding. Sexual dysfunction is frequent and frustrating for both patient and partner. Alterations in sweating and body temperature are not widely recognized but often are present. Autonomic dysfunction can significantly and deleteriously impact quality of life for individuals with Parkinson's disease. Because effective treatment for many aspects of autonomic dysfunction is available, it is vitally important that assessment of autonomic dysfunction be a regular component of the neurologic history and exam and that appropriate treatment be initiated and maintained.

Can the Executive Control Network be Used to Diagnose Parkinson's Disease and as an Efficacy Indicator of Deep Brain Stimulation?

Objective

The aim of this work was to investigate whether there are differences in the executive control network (ECN) between patients with Parkinson's disease (PD) before and after deep brain stimulation (DBS) surgery and to explore how deep brain stimulation (DBS) surgery affects ECN connectivity in patients with PD.

Methods

Resting-state magnetic resonance imaging (MRI) data were obtained from 23 patients with Parkinson's disease preoperatively (pre-PD) and postoperatively (post-PD) and 14 normal controls (CN). The right dorsolateral prefrontal cortex (DLPFC) was used as the seed region of interest (ROI) to study the characteristics of the functional connectivity of the ECN in these subjects.

Results

There were differences in the ECN among PD patients before and after surgery and between the CN. Compared with the CN group, the pre-PD patients showed significantly reduced functional connectivity (FC) between the DLPFC and the left inferior frontal gyrus, left precuneus, left cerebellum posterior lobe, right middle frontal gyrus, right inferior parietal gyrus, right posterior central gyrus, right precuneus, and right inferior frontal gyrus. Compared to the CN group, the post-PD patients showed significantly reduced FC between the DLPFC and left inferior frontal gyrus, left precuneus, left cerebellum posterior lobe, right middle frontal gyrus, right inferior frontal gyrus, and right parietal lobule. There is no difference in the ECN between the pre-PD patients and the post-PD patients.

Conclusions

The FC of ECN in PD patients was different from that in normal controls, but the FC of the ECN in patients with PD may not be altered by DBS. This suggests that the ECN may be considered an imaging biomarker for the identification of PD but may not be a good imaging biomarker for the evaluation of DBS efficacy.

Comparison Between Levodopa-Carbidopa Intestinal Gel Infusion and Subthalamic Nucleus Deep-Brain Stimulation for Advanced Parkinson's Disease: A Systematic Review and Meta-Analysis

Background: Currently, some advanced treatments such as Levodopa-Carbidopa intestinal gel infusion (LCIG), deep-brain stimulation (DBS), and subcutaneous apomorphine infusion have become alternative strategies for advanced Parkinson's disease (PD). However, which treatment is better for individual patients remains unclear. This review aims to compare therapeutic effects of motor and/or non-motor symptoms of advanced PD patients between LCIG and DBS.

Methods: We manually searched electronic databases (PubMed, Embase, Cochrane Library) and reference lists of included articles published until April 04, 2019 using related terms, without language restriction. We included case-controlled cohort studies and randomized-controlled trials, which directly compared differences between LCIG and DBS. The Newcastle-Ottawa scale (NOS), proposed by the Cochrane Collaboration, was utilized to assess the quality of the included studies. Two investigators independently extracted data from each trial. Pooled standard-mean differences (SMDs) and relative risks (RRs) with 95% confidence intervals (CIs) were calculated by meta-analysis. Outcomes were grouped according to the part III and part IV of the Unified Parkinson Disease Rating Scale (UPDRS) and adverse events. We also descriptively reviewed some data, which were unavailable for statistical analysis.

Results: This review included five cohort trials of 257 patients for meta-analysis. There were no significant differences between LCIG and subthalamic nucleus deep-brain stimulation (STN-DBS) on UPDRS-III and adverse events comparisons: UPDRS-III (pooled SMDs = 0.200, 95% CI: −0.126–0.527, P = 0.230), total adverse events (pooled RRs = 1.279, 95% CI: 0.983–1.664, P = 0.067), serious adverse events (pooled RRs = 1.539, 95% CI: 0.664–3.566, P = 0.315). Notably, the improvement of UPDRS-IV was more significant in STN-DBS groups: pooled SMDs = 0.857, 95% CI: 0.130–1.584, P = 0.021. However, the heterogeneity was moderate for UPDRS-IV (I² = 73.8%).

Conclusion: LCIG has comparable effects to STN-DBS on motor function for advanced PD, with acceptable tolerability. More large, well-designed trials are needed to assess the comparability of LCIG and STN-DBS in the future.

[Development of a risk map in an oral and maxillofacial surgical unit]

INTRODUCTION

the main aim of this study was to develop and implement a risk map in the Oral and Maxillofacial Surgery Service of the University Hospital «Virgen de las Nieves» of Granada to minimize the incidence of adverse effects (AE).

MATERIALS AND METHODS

Longitudinal, prospective study carried out in the Oral and Maxillofacial Surgery Service of the Hospital Universitario Virgen de las Nieves of Granada, from June 2017 to May 2018, through the methodology of «Analysis and Failure Mode Effect». Management of the different AE was addressed. The following phases were considered as it follows: identification of the problem, identification of AE for within the practice of the oral and maxillofacial surgery that represents a problem in the assistive safety, creation of an interdisciplinary working group, analysis of the current situation in patient safety and risk management using 2analysis tools, SWOT and PITELO, preparation of the patient care process, development of a catalog of AE and preparation of a risk map.

RESULTS

A total of 33 AE were identified. The risk map showed a higher incidence of AE in the Surgical Area (22) compared to the areas of Outpatient Clinic and Hospital Discharge (6). A total of 10 critical AE were identified.

CONCLUSIONS

The elaboration of a risk map allowed to determine the process of the oral and maxillofacial surgical patient, and to elaborate a catalog of AE.