Usefulness of thalamic beta activity for closed-loop therapy in essential tremor.

A partial loss of effectiveness of deep brain stimulation of the ventral intermediate nucleus of the thalamus (VIM) has been reported in some patients with essential tremor (ET), possibly due to habituation to permanent stimulation. This study focused on the evolution of VIM local-field potentials (LFPs) data over time to assess the long-term feasibility of closed-loop therapy based on thalamic activity. We performed recordings of thalamic LFPs in 10 patients with severe ET using the ACTIVA™ PC + S (Medtronic plc.) allowing both recordings and stimulation in the same region. Particular attention was paid to describing the evolution of LFPs over time from 3 to 24 months after surgery when the stimulation was Off. We demonstrated a significant decrease in high-beta LFPs amplitude during movements inducing tremor in comparison to the rest condition 3 months after surgery (1.91 ± 0.89 at rest vs. 1.27 ± 1.37 µV2/Hz during posture/action for N = 8/10 patients; p = 0.010), 12 months after surgery (2.92 ± 1.75 at rest vs. 2.12 ± 1.78 µV2/Hz during posture/action for N = 7/10 patients; p = 0.014) and 24 months after surgery (2.32 ± 0.35 at rest vs 0.75 ± 0.78 µV2/Hz during posture/action for 4/6 patients; p = 0.017). Among the patients who exhibited a significant decrease of high-beta LFP amplitude when stimulation was Off, this phenomenon was observed at least twice during the follow-up. Although the extent of this decrease in high-beta LFPs amplitude during movements inducing tremor may vary over time, this thalamic biomarker of movement could potentially be usable for closed-loop therapy in the long term.

Personality assessment with Temperament and Character Inventory in Parkinson's disease.

INTRODUCTION: There is a growing interest in personality evaluation in Parkinson's disease (PD), following observations of specific temperaments in PD patients. Therefore, our objective was to evaluate personality dimensions from the Temperament and Character Inventory (TCI) in a cohort of fluctuating PD patients considered for deep brain stimulation. METHODS: Fluctuating PD patients from the PREDISTIM cohort were included. Description of TCI dimensions and comparison with a French normative cohort were performed. Pearson correlations between TCI dimensions and motor, behavioral and cognitive variables were investigated. Structural and internal consistency analysis of the TCI were further assessed. RESULTS: The 570 PD patients presented significant higher scores in Harm Avoidance, Reward Dependence, Persistence, Self-Directedness and Cooperativeness and significant lower scores in Self-Transcendence compared to the French normative cohort; only Novelty Seeking scores were not different. Harm Avoidance and Self-directedness scores were correlated with PDQ-39 total, HAMD, HAMA scores, and anxiolytic/antidepressant treatment. Novelty Seeking scores were correlated with impulsivity. Pearson correlations between TCI dimensions, principal component analysis of TCI sub-dimensions and Cronbach's alpha coefficients showed adequate psychometric proprieties. CONCLUSION: The TCI seems to be an adequate tool to evaluate personality dimensions in PD with good structural and internal consistencies. These fluctuating PD patients also have specific personality dimensions compared to normative French population. Moreover, Harm Avoidance and Self-Directedness scores are associated with anxio-depressive state or quality of life and, and Novelty Seeking scores with impulsivity.

Personality dimensions of patients can change during the course of parkinson's disease.

BACKGROUND: Studies assessing personality dimensions by the "Temperament and Character Inventory" (TCI) have previously found an association between Parkinson's disease (PD) and lower Novelty Seeking and higher Harm Avoidance scores. Here, we aimed to describe personality dimensions of PD patients with motor fluctuations and compare them to a normative population and other PD populations. METHODS: All PD patients awaiting Deep Brain Stimulation (DBS) answered the TCI before neurosurgery. Their results were compared to those of historical cohorts (a French normative population, a de novo PD population, and a PD population with motor fluctuations). RESULTS: Most personality dimensions of our 333 included PD patients with motor fluctuations who are candidates for DBS were different from those of the normative population and some were also different from those of the De Novo PD population, whereas they were similar to those of another population of PD patients with motor fluctuations. CONCLUSIONS: During the course of PD, personality dimensions can change in parallel with the development of motor fluctuations, either due to the evolution of the disease and/or dopaminergic treatments.

A Phase 2 Randomized Trial of Asleep versus Awake Subthalamic Nucleus Deep Brain Stimulation for Parkinson's Disease.

OBJECTIVE: Asleep deep brain stimulation (DBS) for Parkinson's disease (PD) is being performed more frequently; however, motor outcomes and safety of asleep DBS have never been assessed in a prospective randomized trial. METHODS: We conducted a prospective, randomized, noncomparative trial to assess the motor outcomes of asleep DBS. Leads were implanted in the subthalamic nucleus (STN) according to probabilistic stereotactic coordinates with a surgical robot under O-arm© imaging guidance under either general anesthesia without microelectrode recordings (MER) (20 patients, asleep group) or local anesthesia with MER and clinical testing (9 patients, awake group). RESULTS: The mean motor improvement rates on the Unified Parkinson's Disease Rating Scale Part III (UPDRS-3) between OFF and ON stimulation without medication were 52.3% (95% CI: 45.4-59.2%) in the asleep group and 47.0% (95% CI: 23.8-70.2%) in the awake group, 6 months after surgery. Except for a subcutaneous hematoma, we did not observe any complications related to the surgery. Three patients (33%) in the awake group and 8 in the asleep group (40%) had at least one side effect potentially linked with neurostimulation. CONCLUSIONS: Owing to its randomized design, our study supports the hypothesis that motor outcomes after asleep STN-DBS in PD may be noninferior to the standard awake procedure.

Impact of Subthalamic Deep Brain Stimulation on Impulse Control Disorders in Parkinson's Disease: A Prospective Study.

BACKGROUND: Impact of subthalamic deep brain stimulation (DBS) on impulse control disorders (ICD) in Parkinson's disease (PD) remains controversial. OBJECTIVES: The objectives of this study were to analyze the natural history of ICD between baseline and 1 year after subthalamic DBS in patients with PD and to identify predictive factors, taking into account the positions of the active contact and stimulation parameters. METHODS: We analyzed postoperative modifications of ICD based on the multicentric, prospective Predictive Factors and Subthalamic Stimulation in Parkinson's Disease cohort. ICD status and Ardouin Scale of Behaviour in PD were assessed at baseline and 1 year following subthalamic DBS. Location of active contacts within the 3 subthalamic nucleus functional territories was investigated. RESULTS: A total of 217 were patients included. Of the patients, 10.6% had ICD at baseline of which 95.6% improved at 1 year following subthalamic DBS; 3.6% of the patients experienced de novo ICD at 1 year following subthalamic DBS. Dopamine agonist dose reduction (from 309.8 to 109.3 mg) was the main driver of ICD regression (P = 0.05). Higher preoperative dyskinesias were associated with poorer ICD evolution (P = 0.04). Whereas baseline apathy was a risk factor of de novo ICD (P = 0.02), ICD improvement correlated with postoperative apathy (P = 0.004). Stimulation power and position of active contacts-mainly located within the sensorimotor part of the subthalamic nucleus-did not influence ICD. CONCLUSIONS: This 1-year, postoperative follow-up study showed ICD regression and dopaminergic drug reduction with optimal position of the active contacts within the subthalamic nucleus. Whereas patients with PD with preoperative ICD were prone to postoperative apathy, we also showed that those with preoperative apathy had a higher risk to experience postoperative de novo ICD, further highlighting the meaningful influence of postoperative management of dopaminergic medication on outcome and the continuum between apathy and ICD. © 2020 International Parkinson and Movement Disorder Society.

Emotional valence impacts lexical activation and inhibition differently in aging: an emotional Hayling task investigation.

BACKGROUND: Aging is characterized by cognitive changes such as a potential inhibition deficit. However, growing evidence shows that positive valence stimuli enhance performances in older adults to a greater degree than in younger adults. The aim of the present study was to investigate the effect of the emotional valence of words on lexical activation and inhibition in aging by using a new Emotional Hayling Task. METHODS: Thirty-eight younger adults (mean age = 20.11 years) and 38 older adults (mean age = 66.47 years) performed a computerized Emotional Hayling task. Participants had to choose the correct (initiation part) or incorrect (inhibition part) final words of highly predictable incomplete sentences. Final words had a negative or positive emotional valence and were paired for reaction time comparison with neutral words. RESULTS: Response times were faster in younger adults than in older adults in both the initiation and the inhibition parts. In addition, response times indicated that older adults initiated more slowly negative than neutral words while no differences emerged in inhibition. No differences were obtained between negative and neutral words in younger adults. Response times showed faster initiation and inhibition for positive than for neutral words in both age groups. CONCLUSION: These data are consistent with previous findings suggesting a disengagement from the processing of negative versus neutral words in older adults when compared with younger adults. A possible explanation is that activation of negative words in the mental lexicon is weaker in older than in younger adults. Conversely, the positive valence of words seems to enhance both activation and inhibition processes in both young and older adults. These findings suggest that positive stimuli can improve performance.

Diagnosing dementia in multiple system atrophy by applying Movement Disorder Society diagnostic criteria for Parkinson's disease dementia.

INTRODUCTION: Dementia is an exclusion criterion in current consensus diagnostic criteria, while growing evidence suggests the occurrence of cognitive dysfunction and even dementia in multiple system atrophy (MSA) patients. The main goal of this study was to determine if Movement Disorder Society (MDS) Parkinson's disease dementia (PDD) LEVEL-1 criteria are useful in screening for dementia in MSA patients compared to full cognitive testing (LEVEL-2 criteria). METHODS: In this retrospective study, MDS diagnostic criteria for PDD were applied in 111 MSA patients from three centres. LEVEL-1 evaluation (short screening test) was compared to LEVEL-2 examination (extensive neuropsychological gold standard assessment). Sensitivity, specificity, positive and negative predictive values were calculated for LEVEL-1 compared to LEVEL-2. Two Mini Mental State Examination (MMSE) cut-off scores were evaluated (<26 according to MDS procedures for the diagnosis of PDD and <27 which has proven more sensitive in a recent study proposing a short procedure for PDD screening). RESULTS: According to these criteria, 11.7% of MSA patients were demented on LEVEL-2 examination. LEVEL-1 examination showed strong specificity (96.9%) and negative predictive value (94.1%), while sensitivity (53.8%) and positive predictive (70%) value were moderate compared to LEVEL-2 evaluation. Sensitivity increased to 84.6% when using a MMSE threshold <27 for LEVEL-1. Executive dysfunction was the main prevalent finding (52% of all patients), while impairment of memory (15%), language (14%) and visuospatial functions was less frequent (13%). CONCLUSION: Our findings suggest that the MDS PDD short screening test may be useful for the diagnosis of MSA dementia.

Facial emotion recognition is inversely correlated with tremor severity in essential tremor.

We here assess limbic and orbitofrontal control in 20 patients with essential tremor (ET) and 18 age-matched healthy controls using the Ekman Facial Emotion Recognition Task and the IOWA Gambling Task. Our results show an inverse relation between facial emotion recognition and tremor severity. ET patients also showed worse performance in joy and fear recognition, as well as subtle abnormalities in risk detection, but these differences did not reach significance after correction for multiple testing.