Early Parkinson's Disease Phenotypes Tailored by Personality, Behavior, and Motor Symptoms

BACKGROUND

Previous studies described a parkinsonian personality characterized as rigid, introverted, and cautious; however, little is known about personality traits in de novo Parkinson's disease (PD) patients and their relationships with motor and neuropsychiatric symptoms.

OBJECTIVE

To investigate personality in de novo PD and explore its relationship with PD symptoms.

METHODS

Using Cloninger's biosocial model, we assessed personality in 193 de novo PD patients. Motor and non-motor symptoms were measured using several validated scales. Cluster analysis was conducted to investigate the interrelationship of personality traits, motor, and non-motor symptoms.

RESULTS

PD patients showed low novelty seeking, high harm avoidance, and normal reward dependence and persistence scores. Harm avoidance was positively correlated with the severity of depression, anxiety, and apathy (rs = [0.435, 0.676], p < 0.001) and negatively correlated with quality of life (rs = -0.492, p < 0.001). Novelty seeking, reward dependence, and persistence were negatively correlated with apathy (rs = [-0.274, -0.375], p < 0.001). Classification of patients according to personality and PD symptoms revealed 3 distinct clusters: i) neuropsychiatric phenotype (with high harm avoidance and low novelty seeking, hypodopaminergic neuropsychiatric symptoms and higher impulsivity), ii) motor phenotype (with low novelty seeking and higher motor severity), iii) benign phenotype (with low harm avoidance and high novelty seeking, reward dependence, and persistence traits clustered with lower symptoms severity and low impulsivity).

CONCLUSION

Personality in early PD patients allows us to recognize 3 patients' phenotypes. Identification of such subgroups may help to better understand their natural history. Their longitudinal follow-up will allow confirming whether some personality features might influence disease evolution and treatment.

Long-term independence and quality of life after subthalamic stimulation in Parkinson's disease

Background and purpose

Studies on long‐term nonmotor outcomes of subthalamic nucleus stimulation in Parkinson disease (PD) are scarce. This study reports on very long‐term non‐motor and motor outcomes in one of the largest cohorts of people with advanced PD, treated for >10 years with subthalamic nucleus stimulation. The main outcome was to document the evolution of independence in activities of daily living. The secondary outcomes were to measure the change in quality of life, as well as non‐motor and motor outcomes.

Methods

Patients were studied preoperatively, at 1 year, and beyond 10 years after subthalamic stimulation with an established protocol including motor, non‐motor, and neuropsychological assessments.

Results

Eighty‐five people with PD were included. Independence scores in the off‐medication condition (measured with the Schwab & England Activities of Daily Living Scale) as well as quality of life (measured with the Parkinson's Disease Questionnaire [PDQ]‐37) remained improved at longest follow‐up compared to preoperatively (respectively, p < 0.001, p = 0.015). Cognitive scores, measured with the Mattis Dementia Rating Scale, significantly worsened compared to before and 1 year after surgery (p < 0.001), without significant change in depression, measured with the Beck Depression Inventory. Motor fluctuations, dyskinesias, and off dystonia remained improved at longest follow‐up (p < 0.001), with a significant reduction in dopaminergic treatment (45%, p < 0.001).

Conclusions

This study highlights the long‐term improvement of subthalamic stimulation on independence and quality of life, despite the progression of disease and the occurrence of levodopa‐resistant symptoms.

Limbic Serotonergic Plasticity Contributes to the Compensation of Apathy in Early Parkinson's Disease

BACKGROUND

De novo Parkinson's disease (PD) patients with apathy exhibit prominent limbic serotonergic dysfunction and microstructural disarray. Whether this distinctive lesion profile at diagnosis entails different prognosis remains unknown.

OBJECTIVES

To investigate the progression of dopaminergic and serotonergic dysfunction and their relation to motor and nonmotor impairment in PD patients with or without apathy at diagnosis.

METHODS

Thirteen de novo apathetic and 13 nonapathetic PD patients were recruited in a longitudinal double-tracer positron emission tomography cohort study. We quantified the progression of presynaptic dopaminergic and serotonergic pathology using [¹¹ C]PE2I for dopamine transporter and [¹¹ C]DASB for serotonin transporter at baseline and 3 to 5 years later, using linear mixed-effect models and mediation analysis to compare the longitudinal evolution between groups for clinical impairment and region-of-interest-based analysis.

RESULTS

After the initiation of dopamine replacement therapy, apathy, depression, and anxiety improved at follow-up in patients with apathy at diagnosis (n = 10) to the level of patients without apathy (n = 11). Patients had similar progression of motor impairment, whereas mild impulsive behaviors developed in both groups. Striato-pallidal and mesocorticolimbic presynaptic dopaminergic loss progressed similarly in both groups, as did serotonergic pathology in the putamen, caudate nucleus, and pallidum. Contrastingly, serotonergic innervation selectively increased in the ventral striatum and anterior cingulate cortex in apathetic patients, contributing to the reversal of apathy besides dopamine replacement therapy.

CONCLUSION

Patients suffering from apathy at diagnosis exhibit compensatory changes in limbic serotonergic innervation within 5 years of diagnosis, with promising evidence that serotonergic plasticity contributes to the reversal of apathy. The relationship between serotonergic plasticity and dopaminergic treatments warrants further longitudinal investigations. © 2022 International Parkinson and Movement Disorder Society.

The Contribution of Subthalamic Nucleus Deep Brain Stimulation to the Improvement in Motor Functions and Quality of Life

BACKGROUND

Subthalamic nucleus deep brain stimulation (STN-DBS) effectively treats motor symptoms and quality of life (QoL) of advanced and fluctuating early Parkinson's disease. Little is known about the relation between electrode position and changes in symptom control and ultimately QoL.

OBJECTIVES

The relation between the stimulated part of the STN and clinical outcomes, including the motor score of the Unified Parkinson's Disease Rating Scale (UPDRS) and the quality-of-life questionnaire, was assessed in a subcohort of the EARLYSTIM study.

METHODS

Sixty-nine patients from the EARLYSTIM cohort who underwent DBS, with a comprehensive clinical characterization before and 24 months after surgery, were included. Intercorrelations of clinical outcome changes, correlation between the affected functional parts of the STN, and changes in clinical outcomes were investigated. We further calculated sweet spots for different clinical parameters.

RESULTS

Improvements in the UPDRS III and Parkinson's Disease Questionnaire (PDQ-39) correlated positively with the extent of the overlap with the sensorimotor STN. The sweet spots for the UPDRS III (x = 11.6, y = -13.1, z = -6.3) and the PDQ-39 differed (x = 14.8, y = -12.4, z = -4.3) ~3.8 mm.

CONCLUSIONS

The main influence of DBS on QoL is likely mediated through the sensory-motor basal ganglia loop. The PDQ sweet spot is located in a posteroventral spatial location in the STN territory. For aspects of QoL, however, there was also evidence of improvement through stimulation of the other STN subnuclei. More research is necessary to customize the DBS target to individual symptoms of each patient. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Fatigue in de novo Parkinson's Disease: Expanding the Neuropsychiatric Triad?

BACKGROUND

Fatigue is a frequent and troublesome symptom present from the early stages of Parkinson's disease (PD).

OBJECTIVE

To examine the relationship between fatigue and the neuropsychiatric triad, which includes apathy, depression, and anxiety, in de novo PD.

METHODS

We performed a cross-sectional study including 197 patients with de novo PD and assessed fatigue using the Parkinson's Disease Fatigue Scale (PDFS-16). We evaluated motor status using the Unified Parkinson's Disease Rating Scale (UPDRS) part III score and evaluated neuropsychiatric status using the Ardouin Scale of Behavior in Parkinson's Disease (ASBPD). We carried out univariate and multivariate analyses to model association between motor signs, non-motor signs, and fatigue risk.

RESULTS

Frequency of fatigue (28.9%) was of the same order of magnitude as that of apathy. PD patients with fatigue reported a lower quality of life than patients without fatigue (p < 0.0001). The ASBPD showed that patients with fatigue had higher scores for depressed mood (p < 0.0001), anxiety (p < 0.0001), and apathy (p < 0.0001). In the univariate analysis, fatigue score was positively correlated with apathy, depression, anxiety, and the neuropsychiatric triad as a whole, and to a lesser extent with female sex, hyperemotivity, and the UPDRS part III score. In the multivariate analysis, after adjusting for sex and motor status, the fatigue score remained significantly correlated with apathy (OR = 11.17 [4.33-28.78], p < 0.0001) and depression (OR = 4.28 [1.39-13.12], p = 0.01), but not with anxiety (OR = 0.94 [0.34-2.58], p = 0.9).

CONCLUSION

We propose that the neuropsychiatric triad could be expanded to include fatigue.

Consensus Statement on High-Intensity Focused Ultrasound for Functional Neurosurgery in Switzerland

Background: Magnetic resonance-guided high-intensity focused ultrasound (MRgHiFUS) has evolved into a viable ablative treatment option for functional neurosurgery. However, it is not clear yet, how this new technology should be integrated into current and established clinical practice and a consensus should be found about recommended indications, stereotactic targets, patient selection, and outcome measurements.

Objective: To sum up and unify current knowledge and clinical experience of Swiss neurological and neurosurgical communities regarding MRgHiFUS interventions for brain disorders to be published as a national consensus paper.

Methods: Eighteen experienced neurosurgeons and neurologists practicing in Switzerland in the field of movement disorders and one health physicist representing 15 departments of 12 Swiss clinical centers and 5 medical societies participated in the workshop and contributed to the consensus paper. All experts have experience with current treatment modalities or with MRgHiFUS. They were invited to participate in two workshops and consensus meetings and one online meeting. As part of workshop preparations, a thorough literature review was undertaken and distributed among participants together with a list of relevant discussion topics. Special emphasis was put on current experience and practice, and areas of controversy regarding clinical application of MRgHiFUS for functional neurosurgery.

Results: The recommendations addressed lesioning for treatment of brain disorders in general, and with respect to MRgHiFUS indications, stereotactic targets, treatment alternatives, patient selection and management, standardization of reporting and follow-up, and initialization of a national registry for interventional therapies of movement disorders. Good clinical evidence is presently only available for unilateral thalamic lesioning in treating essential tremor or tremor-dominant Parkinson's disease and, to a minor extent, for unilateral subthalamotomy for Parkinson's disease motor features. However, the workgroup unequivocally recommends further exploration and adaptation of MRgHiFUS-based functional lesioning interventions and confirms the need for outcome-based evaluation of these approaches based on a unified registry. MRgHiFUS and DBS should be evaluated by experts familiar with both methods, as they are mutually complementing therapy options to be appreciated for their distinct advantages and potential.

Conclusion: This multidisciplinary consensus paper is a representative current recommendation for safe implementation and standardized practice of MRgHiFUS treatments for functional neurosurgery in Switzerland.

Serotonergic and Dopaminergic Lesions Underlying Parkinsonian Neuropsychiatric Signs

BACKGROUND

Parkinson's disease (PD) is characterized by heterogeneous motor and nonmotor manifestations related to alterations in monoaminergic neurotransmission systems. Nevertheless, the characterization of concomitant dopaminergic and serotonergic dysfunction after different durations of Parkinson's disease, as well as their respective involvement in the expression and severity of neuropsychiatric signs, has gained little attention so far.

METHODS

To fill this gap, we conducted a cross-sectional study combining clinical and dual-tracer positron emission tomography (PET) neuroimaging approaches, using radioligands of dopamine ([¹¹ C]-N-(3-iodoprop-2E-enyl)-2-beta-carbomethoxy-3-beta-(4-methylphenyl)-nortropane) ([¹¹ C]PE2I) and serotonin ([¹¹ C]-N,N-dimethyl-2-(-2-amino-4-cyanophenylthio)-benzylamine) ([¹¹ C]DASB) reuptake, after different durations of Parkinson's disease (ie, in short-disease duration drug-naive de novo (n = 27, 0-2 years-duration), suffering from apathy (n = 14) or not (n = 13); intermediate-disease duration (n = 15, 4-7 years-duration) and long-disease duration, non-demented (n = 15, 8-10 years-duration) patients). Fifteen age-matched healthy subjects were also enrolled.

RESULTS

The main findings are threefold: (1) both dopaminergic and serotonergic lesions worsen with the duration of Parkinson's disease, spreading from midbrain/subcortical to cortical regions; (2) the presence of apathy at PD onset is associated with more severe cortical and subcortical serotonergic and dopaminergic disruption, similar to the denervation pattern observed in intermediate-disease duration patients; and (3) the severity of parkinsonian apathy, depression, and trait-anxiety appears primarily related to serotonergic alteration within corticostriatal limbic areas.

CONCLUSIONS

Altogether, these findings highlight the prominent role of serotonergic degeneration in the expression of several neuropsychiatric symptoms occurring after different durations of Parkinson's disease. © 2021 International Parkinson and Movement Disorder Society.

Subthalamic and pallidal deep brain stimulation for Parkinson's disease-meta-analysis of outcomes

Although deep brain stimulation (DBS) of the globus pallidus internus (GPi) and the subthalamic nucleus (STN) has become an established treatment for Parkinson’s disease (PD), a recent meta-analysis of outcomes is lacking. To address this gap, we performed a meta-analysis of bilateral STN- and GPi-DBS studies published from 1990-08/2019. Studies with ≥10 subjects reporting Unified Parkinson’s Disease Rating Scale (UPDRS) III motor scores at baseline and 6–12 months follow-up were included. Several outcome variables were analyzed and adverse events (AE) were summarized. 39 STN studies (2035 subjects) and 5 GPi studies (292 subjects) were eligible. UPDRS-II score after surgery in the stimulation-ON/medication-OFF state compared to preoperative medication-OFF state improved by 47% with STN-DBS and 18.5% with GPi-DBS. UPDRS-III score improved by 50.5% with STN-DBS and 29.8% with GPi-DBS. STN-DBS improved dyskinesia by 64%, daily OFF time by 69.1%, and quality of life measured by PDQ-39 by 22.2%, while Levodopa Equivalent Daily Dose (LEDD) was reduced by 50.0%. For GPi-DBS information regarding dyskinesia, OFF time, PDQ-39 and LEDD was insufficient for further analysis. Correlation analysis showed that preoperative L-dopa responsiveness was highly predictive of the STN-DBS motor outcome across all studies. Most common surgery-related AE were infection (5.1%) and intracranial hemorrhage (3.1%). Despite a series of technological advances, outcomes of modern surgery are still comparable with those of the early days of DBS. Recent changes in target selection with a preference of GPi in elderly patients with cognitive deficits and more psychiatric comorbidities require more published data for validation.

Contribution of Basal Ganglia to the Sense of Upright: A Double-Blind Within-Person Randomized Trial of Subthalamic Stimulation in Parkinson's Disease with Pisa Syndrome

BACKGROUND

Verticality perception is frequently altered in Parkinson's disease (PD) with Pisa syndrome (PS). Is it the cause or the consequence of the PS?

OBJECTIVE

We tested the hypothesis that both scenarios coexist.

METHODS

We performed a double-blind within-person randomized trial (NCT02704910) in 18 individuals (median age 63.5 years) with PD evolving for a median of 17.5 years and PS for 2.5 years and treated with bilateral stimulation of the subthalamus nuclei (STN-DBS) for 6.5 years. We analyzed whether head and trunk orientations were congruent with the visual (VV) and postural (PV) vertical, and whether switching on one or both sides of the STN-DBS could modulate trunk orientation via verticality representation.

RESULTS

The tilted verticality perception could explain the PS in 6/18 (33%) patients, overall in three right-handers (17%) who showed net and congruent leftward trunk and PV tilts. Two of the 18 (11%) had an outstanding clinical picture associating leftward: predominant parkinsonian symptoms, whole-body tilt (head -11°, trunk -8°) and transmodal tilt in verticality perception (PV -10°, VV -8.9°). Trunk orientation or VV were not modulated by STN-DBS, whereas PV tilts were attenuated by unilateral or bilateral stimulations if it was applied on the opposite STN.

CONCLUSION

In most cases of PS, verticality perception is altered by the body deformity. In some cases, PS seems secondary to a biased internal model of verticality, and DBS on the side of the most denervated STN attenuated PV tilts with a quasi-immediate effect. This is an interesting track for further clinical studies.

Assessment of Affective-Behavioral States in Parkinson's Disease Patients: Towards a New Screening Tool

BACKGROUND

Assessment of affective-behavioral states in patients with Parkinson's disease (PD) undergoing deep brain stimulation (DBS) is essential.

OBJECTIVE

To analyze well-established questionnaires as a pilot-study with the long term aim to develop a screening tool evaluating affective-behavioral dysfunction, including depression, anxiety, apathy, mania, and impulse control disorders, in PD patients screened for DBS.

METHODS

Two hundred ninety-seven inpatients with PD underwent standardized neuropsychiatric testing including German versions of Beck Depression Inventory-II, Hospital Anxiety and Depression Scale, Apathy Evaluation Scale, Self-Report Manic Inventory, and Questionnaire for Impulsive-Compulsive Disorders in PD-Rating Scale, to assess appropriateness for DBS. Statistical item reduction was based on exploratory factor analysis, Cronbach's alpha, item-total correlations, item difficulty, and inter-item correlations. Confirmatory factor analysis was conducted to assess factorial validity. An expert rating was performed to identify clinically relevant items in the context of PD and DBS, to maintain content validity. We compared the shortened subscales with the original questionnaires using correlations. To determine cutoff points, receiver operating characteristics analysis was performed.

RESULTS

The items of the initial questionnaires were reduced from 129 to 38 items. Results of confirmatory factor analyses supported the validity of the shortened pool. It demonstrated high internal consistency (Cronbach's alpha = 0.72-0.83 across subscales), and the individual subscales were correlated with the corresponding original scales (rs = 0.84-0.95). Sensitivities and specificities exceeded 0.7.

CONCLUSION

The shortened item pool, including 38 items, provides a good basis for the development of a screening tool, capturing affective-behavioral symptoms in PD patients before DBS implantation. Confirmation of the validity of such a screening tool in an independent sample of PD patients is warranted.

Long-term Outcomes (15 Years) After Subthalamic Nucleus Deep Brain Stimulation in Patients With Parkinson Disease

OBJECTIVE

To evaluate the effects of deep brain stimulation of the subthalamic nucleus (STN-DBS) on motor complications in patients with Parkinson disease (PD) beyond 15 years after surgery.

METHODS

Data on motor complications, quality of life (QoL), activities of daily living, Unified Parkinson's Disease Rating Scale motor scores, dopaminergic treatment, stimulation measures, and side effects of STN-DBS were retrospectively retrieved and compared before surgery, at 1 year, and beyond 15 years after bilateral STN-DBS.

RESULTS

Fifty-one patients with 17.06 ± 2.18 years STN-DBS follow-up were recruited. Compared to baseline, the time spent with dyskinesia and the time spent in the "off" state were reduced by 75% (p < 0.001) and by 58.7% (p < 0.001), respectively. Moreover, dopaminergic drugs were reduced by 50.6% (p < 0.001). Parkinson's Disease Quality of Life Questionnaire total score and the emotional function and social function domains improved 13.8% (p = 0.005), 13.6% (p = 0.01), and 29.9% (p < 0.001), respectively. Few and mostly manageable device-related adverse events were observed during the follow-up.

CONCLUSIONS

STN-DBS is effective beyond 15 years from the intervention, notably with significant improvement in motor complications and stable reduction of dopaminergic drugs. Furthermore, despite the natural continuous progression of PD with worsening of levodopa-resistant motor and nonmotor symptoms over the years, patients undergoing STN-DBS could maintain an improvement in QoL.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that, for patients with PD, STN-DBS remains effective at treating motor complications 15 years after surgery.

Robot-induced hallucinations in Parkinson's disease depend on altered sensorimotor processing in fronto-temporal network

Hallucinations in Parkinson's disease (PD) are disturbing and frequent non-motor symptoms and constitute a major risk factor for psychosis and dementia. We report a robotics-based approach applying conflicting sensorimotor stimulation, enabling the induction of presence hallucinations (PHs) and the characterization of a subgroup of patients with PD with enhanced sensitivity for conflicting sensorimotor stimulation and robot-induced PH. We next identify the fronto-temporal network of PH by combining MR-compatible robotics (and sensorimotor stimulation in healthy participants) and lesion network mapping (neurological patients without PD). This PH-network was selectively disrupted in an additional and independent cohort of patients with PD, predicted the presence of symptomatic PH, and associated with cognitive decline. These robotics-neuroimaging findings extend existing sensorimotor hallucination models to PD and reveal the pathological cortical sensorimotor processes of PH in PD, potentially indicating a more severe form of PD that has been associated with psychosis and cognitive decline.

Changing Gears - DBS For Dopaminergic Desensitization in Parkinson's Disease?

In Parkinson's disease, both motor and neuropsychiatric complications unfold as a consequence of both incremental striatal dopaminergic denervation and intensifying long-term dopaminergic treatment. Together, this leads to 'dopaminergic sensitization' steadily increasing motor and behavioral responses to dopaminergic medication that result in the detrimental sequalae of long-term dopaminergic treatment. We review the clinical presentations of 'dopaminergic sensitization', including rebound off and dyskinesia in the motor domain, and neuropsychiatric fluctuations and behavioral addictions with impulse control disorders and dopamine dysregulation syndrome in the neuropsychiatric domain. We summarize state-of-the-art deep brain stimulation, and show that STN-DBS allows dopaminergic medication to be tapered, thus supporting dopaminergic desensitization. In this framework, we develop our integrated debatable viewpoint of "changing gears", that is we suggest rethinking earlier use of subthalamic nucleus deep brain stimulation, when the first clinical signs of dopaminergic motor or neuropsychiatric complications emerge over the steadily progressive disease course. In this sense, subthalamic deep brain stimulation may help reduce longitudinal motor and neuropsychiatric symptom expression - importantly, not by neuroprotection but by supporting dopaminergic desensitization through postoperative medication reduction. Therefore, we suggest considering STN-DBS early enough before patients encounter potentially irreversible psychosocial consequences of dopaminergic complications, but importantly not before a patient shows first clinical signs of dopaminergic complications. We propose to consider neuropsychiatric dopaminergic complications as a new inclusion criterion in addition to established motor criteria, but this concept will require validation in future clinical trials. ANN NEUROL 2021.

Reckless Generosity, Parkinson's Disease and Dopamine: A Case Series and Literature Review

BACKGROUND

Impulse control disorders (ICDs) are a frequent side effect of dopamine replacement therapy (DRT) in Parkinson's disease (PD). Reckless generosity might expand the spectrum of known ICDs.

CASES

Over 18 months, we encountered three PD patients exhibiting reckless generosity under DRT, leading to disastrous financial and social consequences.

LITERATURE REVIEW

Except for another case series describing reckless generosity in three PD patients, only one study has examined generosity in PD patients; with findings suggesting that PD patients with ICDs are less sensitive to the aversive aspects of the lack of reciprocation in social settings. Studies with healthy individuals suggest that increased availability of dopamine might reduce social discounting and promote egalitarian behavior, and thereby increase generous behavior towards strangers. Genetic studies show that polymorphisms in dopamine D4 receptors influence generous behavior.

CONCLUSIONS

Reckless generosity in PD patients with DRT might be underreported and should therefore be carefully be screened for by clinicians. A potential mechanism underlying this ICD-related behavior might be a sensitization of the mesolimbic and mesocortical dopaminergic system, leading to reduced social discounting and maladaptive reward-learning. Further research is needed to investigate the prevalence and underlying mechanisms of reckless generosity in PD patients.

Apathy Induced by Subthalamic Nucleus Deep Brain Stimulation in Parkinson's Disease: A Meta-Analysis

Apathy, the loss of motivation, is a common problem in Parkinson's disease (PD) and often observed following deep brain stimulation (DBS) of the subthalamic nucleus (STN). The aim of this meta-analysis was to determine the occurrence of apathy following STN DBS in literature. Relevant articles were searched in PubMed/Medline, SCOPUS, EMBASE, and Web of Sciences electronic databases. Studies were included if they reported apathy scores pre- and post-DBS or the cross-sectional difference between PD patients receiving STN DBS and patients receiving medication only. Thirty-three articles were included in the meta-analyses from 6,658 screened articles by two authors independently. A total of 1,286 patients were included with a mean age (±standard deviation [SD]) of 58.4 ± 8.5 years and a disease duration of 11.0 ± 5.8 years. The apathy score measured by means of the Apathy Evaluation Scale (AES), Starkstein Apathy Scale (SAS), and the Lille Apathy Rating Scale (LARS) was significantly higher after DBS than pre-operatively (g = 0.34, 95% confidence interval [CI] = 0.19-0.48, P < 0.001). An equal, significant difference in severity of apathy was found between STN DBS and medication only (g = 0.36, 95% CI = 0.03-0.65; P = 0.004). Statistical heterogeneity was moderately high, but the effects stood strong after multiple analyses and were independent of tapering off dopaminergic medication. The findings of this meta-analysis indicate that apathy is increased after STN DBS compared to the pre-operative state and to medication only (systematic review registration number: PROSPERO CRD42019133932). © 2020 Universiteit van Amsterdam. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Predictors of Long-Term Outcome of Subthalamic Stimulation in Parkinson Disease

OBJECTIVE

This study was undertaken to identify preoperative predictive factors of long-term motor outcome in a large cohort of consecutive Parkinson disease (PD) patients with bilateral subthalamic nucleus deep brain stimulation (STN-DBS).

METHODS

All consecutive PD patients who underwent bilateral STN-DBS at the Grenoble University Hospital (France) from 1993 to 2015 were evaluated before surgery, at 1 year (short-term), and in the long term after surgery. All available demographic variables, neuroimaging data, and clinical characteristics were collected. Preoperative predictors of long-term motor outcome were investigated by performing survival and univariate/multivariate Cox regression analyses. Loss of motor benefit from stimulation in the long term was defined as a reduction of less than 25% in the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III scores compared to the baseline off-medication scores. As a secondary objective, potential predictors of short-term motor outcome after STN-DBS were assessed by performing univariate and multivariate linear regression analyses.

RESULTS

In the long-term analyses (mean follow-up = 8.4 ± 6.26 years, median = 10 years, range = 1-17 years), 138 patients were included. Preoperative higher frontal score and off-medication MDS-UPDRS part III scores predicted a better long-term motor response to stimulation, whereas the presence of vascular changes on neuroimaging predicted a worse motor outcome. In 357 patients with available 1-year follow-up, preoperative levodopa response, tremor dominant phenotype, baseline frontal score, and off-medication MDS-UPDRS part III scores predicted the short-term motor outcome.

INTERPRETATION

Frontal lobe dysfunction, disease severity in the off-medication condition, and the presence of vascular changes on neuroimaging represent the main preoperative clinical predictors of long-term motor STN-DBS effects. ANN NEUROL 2021;89:587-597.

A case series and systematic review of rapid eye movement sleep behavior disorder outcome after deep brain stimulation in Parkinson's disease

REM-sleep behavior disorder (RBD) is a parasomnia and a common sleep disorder in Parkinson's disease (PD). While deep brain stimulation (DBS) is an established treatment for advanced PD with beneficial effects on cardinal PD motor symptoms, the data on the impact of DBS on RBD are limited and often controversial. We reviewed published articles that reported on RBD in the context of DBS surgery via systematic PubMed search. We identified 75 studies and included 12 studies, involving a total of 320 subjects, in our review. Results in respect to EMG activity outcome after subthalamic stimulation are inconsistent. We found no study that reported on RBD outcome after pallidal DBS and no DBS study quantified complex behavior during REM sleep. We also added data on RBD outcome after subthalamic (N = 4 patients) or pallidal (N = 3 patients) DBS from patients with PD with RBD, obtained as part of a prospective DBS study in our centre. Our case series showed an increase of complex behavior during REM (CB-REM) after surgery, independent of DBS target. Conversely, we found a trend towards increasing REM sleep without atonia (RSWA) in subthalamic-stimulated patients and a trend towards decreased RSWA in pallidal stimulated patients. We conclude that CB-REM and RSWA might represent two distinct elements in RBD and should be assessed separately, especially in studies that report on RBD outcome after treatment interventions. Further, larger, prospective, controlled studies in different DBS targets, reporting separately on the different RBD modalities, are needed.

Deep brain stimulation of the subthalamic nucleus in obsessive-compulsives disorders: long-term follow-up of an open, prospective, observational cohort

BACKGROUND

Obsessive-compulsive disorder (OCD) is a major cause of disability in western country and responsible for severe impairment of quality of life. About 10% of patients present with severe OCD symptoms and require innovative treatment such as deep brain stimulation (DBS). Among possible targets, the non-motor subthalamic nucleus (STN) is a key node of the basal ganglia circuitry, strongly connected to limbic cortical areas known to be involved in OCD.

METHOD

We analysed, in a prospective, observational, monocentric, open label cohort, the effect of chronic non-motor STN-DBS in 19 patients with treatment-resistant OCD consecutively operated in a single centre. Severity of OCD was evaluated using the Yale and Brown Obsessive-Compulsive Scale (YBOCS). YBOCS scores at 6, 12 and 24 months postoperatively were compared with baseline. Responders were defined by >35% improvement of YBOCS scores. Global Assessment Functioning (GAF) scale was used to evaluate the impact of improvement.

RESULTS

At a 24-month follow-up, the mean YBOCS score improved by 53.4% from 33.3±3.5 to 15.8±9.1 (95% CI 11.2-20.4; p<0.0001). Fourteen out of 19 patients were considered as responders, 5 out of 19 being improved over 75% and 10 out of 19 over 50%. GAF scale improved by 92% from 34.1±3.9 to 66.4±18.8 (95% CI 56.7-76.1; p=0.0003). The most frequent adverse events consisted of transient DBS-induced hypomania and anxiety.

CONCLUSION

Chronic DBS of the non-motor STN is an effective and relatively safe procedure to treat severe OCD resistant to conventional management.

Embarrassment and Shame in People With Parkinson's Disease: A New Tool for Self-Assessment

Shame and embarrassment related to Parkinson's disease (PD) are rarely addressed in clinical practice nor studied in neuroscience research, partly because no specific tool exists to detect them in PD. Objective: To develop a self-applied assessment tool of shame and embarrassment specifically related to PD or its treatment, to promptly identify the presence and severity of these two emotions in PD. Methods: Identification and selection of relevant items were obtained from the collection of PD patients' opinions during support groups and interviews. Several further items were added following a literature review. Subsequently, a two-phase pilot study was performed for identification of ambiguous items and omissions, and to obtain preliminary data on acceptability, reliability, validity and relevance of the new scale (SPARK). Results: A total of 105 PD patients were enrolled in the study. Embarrassment was reported in 85% of patients, while shame was present in 26%. Fifteen percent of patients did not describe any shame or embarrassment. On average, the intensity of these two emotions was low with a marked floor effect in SPARK items and subscales. However, SPARK total score inter-individual variability was important (range 1-84 out of 99). Acceptability and quality of data were satisfactory with no floor or ceiling effects (2.9% each) or missing data. Internal consistency (Cronbach's alpha) was 0.94 for total score and 0.73-0.87 for subscales. The scale correlated ≥0.60 with instruments measuring related constructs. Content validity was satisfactory. SPARK total score strongly correlated with impaired health-related quality of life (r_S = 0.81), the propensity to feel embarrassed or ashamed (r_S = 0.68 and 0.66, respectively), and anxiety (r_S = 0.72) and depression (r_S = 0.63) levels. Moderate to high correlations were observed between SPARK total score and apathy (r_S = 0.46) and a more pronounced personality trait directed toward harm avoidance (r_S = 0.46). No significant differences in SPARK scores were found by sex, education level, PD duration, Hoehn and Yahr stages or PD phenotype. Conclusion: Preliminary analysis of psychometric properties suggests that SPARK could be an acceptable and reliable instrument for assessing shame and embarrassment in PD. SPARK could help healthcare professionals to identify and characterize PD-induced shame and embarrassment.

Deep Brain Stimulation Impact on Social and Occupational Functioning in Parkinson's Disease with Early Motor Complications

Background

Deep brain stimulation (DBS) improves motor symptoms and quality of life in patients with Parkinson's disease (PD) and early motor complications, suggesting that DBS could be prescribed to the working‐age PD population.

Objectives

To investigate the effect of DBS compared with best medical therapy (BMT) on social, psychosocial, and occupational functioning in patients with PD ≤60 years of age with early motor complications, its correlates, and possible underlying rationale.

Methods

Methods included analyses of the Social and Occupational Functioning Assessment Scale, Scales for Outcomes for Parkinson's–Psychosocial, Professional Fitness, Starkstein Apathy Scale, and Schwab and England Activities of Daily Living Scale from the EARLYSTIM study.

Results

Compared with BMT, DBS resulted in significantly greater improvements from baseline through 24 months in social,occupational, and psychosocial functioning. Yet, work status in the 2 groups did not differ at baseline and 24 months. Physicians reported a significantly higher percentage of patients in the BMT group unable to work at 24 months relative to baseline compared with the DBS group. Apathy was significantly worse in patients for whom physicians overrated ability to work when compared with patients’ own ratings than in the group of patients who physicians' ability to work ratings were comparable to, or worse than, patients' self‐ratings of ability to work.

Conclusions

For patients aged ≤60 years with PD and early motor complications, DBS provided significant improvements in social, occupational, and psychosocial function, but not in the actual work engagement compared with BMT at 2 years. Apathy may impact ability to work.

Management of Impulse Control Disorders with Subthalamic Nucleus Deep Brain Stimulation in Parkinson's Disease

Impulse Control Disorders (ICDs) and related disorders are common side effects of dopaminergic treatment in Parkinson's Disease (PD) and are associated with negative effects on mental and physical health, quality of life and interpersonal relationships. Current management options are limited, as a reduction of dopaminergic medication often leads to worsening of motor symptoms or dopamine agonist withdrawal syndrome. The aim of this review was to investigate if ICDs improve, worsen, or remain stable after Subthalamic Nucleus Deep Brain Stimulation (STN-DBS). We reviewed retrospective, prospective and randomized-controlled studies published between 2000 and 2019 examining the effect of STN-DBS on one or more ICDs. The number of participants, time of follow-up, methods used to measure ICDs, type of ICDs, the incidence of ICDs before STN-DBS, the incidence of improvement (remission or reduction) of ICDs after STN-DBS, the incidence of de novo ICDs after STN-DBS, stimulation parameters, lead position, change in motor score and change in medication are reported for each study. Available studies suggest that ICDs improve after STN-DBS in most patients and that persisting new-onset ICDs induced by STN-DBS are rare. However, more randomized-controlled studies are needed to confirm the findings and to further investigate the underlying mechanisms.

Subthalamic nucleus activity dynamics and limb movement prediction in Parkinson's disease

Whilst exaggerated bursts of beta frequency band oscillatory synchronization in the subthalamic nucleus have been associated with motor impairment in Parkinson's disease, a plausible mechanism linking the two phenomena has been lacking. Here we test the hypothesis that increased synchronization denoted by beta bursting might compromise information coding capacity in basal ganglia networks. To this end we recorded local field potential activity in the subthalamic nucleus of 18 patients with Parkinson's disease as they executed cued upper and lower limb movements. We used the accuracy of local field potential-based classification of the limb to be moved on each trial as an index of the information held by the system with respect to intended action. Machine learning using the naïve Bayes conditional probability model was used for classification. Local field potential dynamics allowed accurate prediction of intended movements well ahead of their execution, with an area under the receiver operator characteristic curve of 0.80 ± 0.04 before imperative cues when the demanded action was known ahead of time. The presence of bursts of local field potential activity in the alpha, and even more so, in the beta frequency band significantly compromised the prediction of the limb to be moved. We conclude that low frequency bursts, particularly those in the beta band, restrict the capacity of the basal ganglia system to encode physiologically relevant information about intended actions. The current findings are also important as they suggest that local subthalamic activity may potentially be decoded to enable effector selection, in addition to force control in restorative brain-machine interface applications.

Modeling of Electric Fields in Individual Imaging Atlas for Capsular Threshold Prediction of Deep Brain Stimulation in Parkinson's Disease: A Pilot Study

Background: Modeling of deep brain stimulation electric fields and anatomy-based software might improve post-operative management of patients with Parkinson's disease (PD) who have benefitted from subthalamic nucleus deep brain stimulation (STN-DBS).

Objective: We compared clinical and software-guided determination of the thresholds for current diffusion to the pyramidal tract, the most frequent limiting side effect in post-operative management of STN-DBS PD patients.

Methods: We assessed monopolar reviews in 16 consecutive STN-DBS PD patients and retrospectively compared clinical capsular thresholds, which had been assessed according to standard clinical practice, to those predicted by volume of tissue activated (VTA) model software. All the modeling steps were performed blinded from patients' clinical evaluations.

Results: At the group level, we found a significant correlation (p = 0.0001) when performing statistical analysis on the z-scored capsular thresholds, but with a low regression coefficient (r = 0.2445). When considering intra-patient analysis, we found significant correlations (p < 0.05) between capsular threshold as modeled with the software and capsular threshold as determined clinically in five patients (31.2%).

Conclusions: In this pilot study, the VTA model software was of limited assistance in identifying capsular thresholds for the whole cohort due to a large inter-patient variability. Clinical testing remains the gold standard in selecting stimulation parameters for STN-DBS in PD.