Action tremor in Parkinson's disease: frequency and relationship to motor and non-motor signs

Using electromagnetic articulography to investigate tongue, lip and jaw tremor associated with Parkinson's disease

Tremor in Parkinson's disease is most frequently studied in the limbs, even though it also occurs in the vocal tract. In the current study, we assessed the presence of tongue, lip and jaw tremor in 34 individuals with Parkinson's disease (IwPD) and 25 controls (CS). We used electromagnetic articulography sensors attached to the tongue, the lips, and the jaw to measure orolingual tremor while the participants were performing a series of tasks. Additionally, we acoustically measured frequency and amplitude tremor of the voice in a sustained phonation task. Our findings revealed that IwPD showed significantly more tongue, lip, and jaw tremor than CS. Kinematic tremor frequency and RMS amplitude did not differ between IwPD and CS. We found no group difference in voice tremor prevalence or frequency in our acoustic analysis. While intensity and power indices seemed stronger in IwPD compared to CS, these differences were not significant. We show that electromagnetic articulography is suited for identifying orolingual tremor. While kinematic tremor was more prevalent in IwPD, it also appeared in CS, underlining the importance of including control participants in this type of study.

Parkinsonism plus syndrome in neurosyphilis: Clinical insights and brain imaging

BACKGROUND

While Parkinsonism plus syndrome (PPS) is one of several atypical manifestations in neurosyphilis patients, its clinical features and brain-related manifestations are inadequately documented. In this cross-sectional study, we endeavored to indicate some key clinical and imaging features of neurosyphilis patients, particularly those specific to PPS.

METHODS

We retrospectively included all syphilis patients enrolled in the study from January 2021 to February 2024. All in all, 54 neurosyphilis patients with PPS were recruited. Their socio-demographical features, clinical status, presentations, laboratory manifestations and neuroimaging were analyzed retrospectively.

RESULTS

The predominant phenotype was general paresis (GP). Median age at onset was 50 years, and 87.0 % of the patients were male. Bradykinesia (53.7 %) was the most common manifestation of PPS in neurosyphilis patients. The most frequent physical sign was orofacial dyskinesia (the Candy sign), which accounted for 51.9 % of cases. In nearly three quarters (71.1 %), magnetic resonance imagery revealed temporal, hippocampal lobe, or whole brain atrophy, while 13.3 % exhibited basal ganglia lacunar infarction, and 22.2 % cases had focal demyelination in the cerebral peduncle, cerebellum, frontal lobe, parietal lobe, hippocampus and/or lateral vertical.

CONCLUSIONS

Neurosyphilis patients exhibited PPS in involving bradykinesia, tremor rigidity and, in most cases, GP. Brain atrophy and basal ganglia lesion were the most common imaging findings in neurosyphilis patients with PPS. Our results should help to elucidate PPS characteristics PPS and neuroimaging mechanisms in neurosyphilis patients with PPS.

Neurocognitive Impairment and Social Cognition in Parkinson's Disease Patients

In addition to motor symptoms, neurocognitive impairment (NCI) affects patients with prodromal Parkinson's disease (PD). NCI in PD ranges from subjective cognitive complaints to dementia. The purpose of this review is to present the available evidence of NCI in PD and highlight the heterogeneity of NCI phenotypes as well as the range of factors that contribute to NCI onset and progression. A review of publications related to NCI in PD up to March 2023 was performed using PubMed/Medline. There is an interconnection between the neurocognitive and motor symptoms of the disease, suggesting a common underlying pathophysiology as well as an interconnection between NCI and non-motor symptoms, such as mood disorders, which may contribute to confounding NCI. Motor and non-motor symptom evaluation could be used prognostically for NCI onset and progression in combination with imaging, laboratory, and genetic data. Additionally, the implications of NCI on the social cognition of afflicted patients warrant its prompt management. The etiology of NCI onset and its progression in PD is multifactorial and its effects are equally grave as the motor effects. This review highlights the importance of the prompt identification of subjective cognitive complaints in PD patients and NCI management.

[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.

A Wearable Vibratory Device (The Emma Watch) to Address Action Tremor in Parkinson Disease: Pilot Feasibility Study

BACKGROUND

Parkinson disease (PD) is a neurodegenerative disease that has a wide range of motor symptoms, such as tremor. Tremors are involuntary movements that occur in rhythmic oscillations and are typically categorized into rest tremor or action tremor. Action tremor occurs during voluntary movements and is a debilitating symptom of PD. As noninvasive interventions are limited, there is an ever-increasing need for an effective intervention for individuals experiencing action tremors. The Microsoft Emma Watch, a wristband with 5 vibrating motors, is a noninvasive, nonpharmaceutical intervention for tremor attenuation.

OBJECTIVE

This pilot study investigated the use of the Emma Watch device to attenuate action tremor in people with PD.

METHODS

The sample included 9 people with PD who were assessed on handwriting and hand function tasks performed on a digitized tablet. Tasks included drawing horizontal or vertical lines, tracing a star, spiral, writing "elelelel" in cursive, and printing a standardized sentence. Each task was completed 3 times with the Emma Watch programmed at different vibration intensities, which were counterbalanced: high intensity, low intensity (sham), and no vibration. Digital analysis from the tablet captured kinematic, dynamic, and spatial attributes of drawing and writing samples to calculate mathematical indices that quantify upper limb motor function. APDM Opal sensors (APDM Wearable Technologies) placed on both wrists were used to calculate metrics of acceleration and jerk. A questionnaire was provided to each participant after using the Emma Watch to gain a better understanding of their perspectives of using the device. In addition, drawings were compared to determine whether there were any visual differences between intensities.

RESULTS

In total, 9 people with PD were tested: 4 males and 5 females with a mean age of 67 (SD 9.4) years. There were no differences between conditions in the outcomes of interest measured with the tablet (duration, mean velocity, number of peaks, pause time, and number of pauses). Visual differences were observed within a small subset of participants, some of whom reported perceived improvement. The majority of participants (8/9) reported the Emma Watch was comfortable, and no problems with the device were reported.

CONCLUSIONS

There were visually depicted and subjectively reported improvements in handwriting for a small subset of individuals. This pilot study was limited by a small sample size, and this should be taken into consideration with the interpretation of the quantitative results. Combining vibratory devices, such as the Emma Watch, with task specific training, or personalizing the frequency to one's individual tremor may be important steps to consider when evaluating the effect of vibratory devices on hand function or writing ability in future studies. While the Emma Watch may help attenuate action tremor, its efficacy in improving fine motor or handwriting skills as a stand-alone tool remains to be demonstrated.

Non-Invasive Transcutaneous Afferent Patterned Stimulation Therapy Offers Action Tremor Relief in Parkinson's Disease

Background

Many patients with Parkinson's disease (PD) experience action tremor (including postural and kinetic tremors) that impair activities of daily living. Transcutaneous afferent patterned stimulation (TAPS) is a non-invasive neuromodulation therapy that modulates tremorgenic activity at the ventral intermediate nucleus (VIM). Most TAPS evidence evaluated relief of action tremor associated with essential tremor (ET). This study evaluated whether TAPS results in similar relief of action tremor associated with PD.

Methods

Forty PD patients with action tremors were enrolled in a prospective, single-arm, open-label study with four weeks of unsupervised at-home TAPS sessions in the dominant hand twice daily in between supervised TAPS sessions at two telemedicine appointments. The primary endpoint was change in tremor power as measured by the on-board accelerometer before and immediately after a stimulation session. Additional study endpoints included change in Movement Disorder Society-Sponsored Unified Parkinson's Disease Rating Scale Part III (MDS-UPDRS), change in Bain and Findley Activities of Daily Living (BF-ADL) scale, and clinician and patient global impressions of improvement (CGI-I and PGI-I).

Results

TAPS reduced tremor power by 64% (54%-79%) (median (interquartile range), p < 0.001), with 79% of patients experiencing at least 50% reduction. When comparing pre-stimulation scores at visit 1 to post-stimulation scores at visit 2, TAPS improved per-task MDS-UPDRS III ratings of postural and kinetic tremors (0.6 ± 0.5, t(34) = 7.05, p < 0.001) and per-task patient-ratings of BF-ADL ADL upper limb motion ratings (0.5 ± 0.5, t(34) = 5.69, p < 0.001). Clinicians reported improvement in 78-83% of patients and 75-80% of patients reported improvement. Adverse events, most commonly skin reaction at the stimulation site, occurred in 18% of patients.

Conclusion

Objective, clinician-rated, and patient-rated assessments demonstrated that TAPS provided clinically meaningful relief of action tremor in patients with PD.

Risk factors for developing dyskinesia among Parkinson's disease patients with wearing-off: J-FIRST

BACKGROUND

Dyskinesia frequently occurs during long-term treatment with levodopa in patients with Parkinson's disease (PD) and impacts quality of life. Few studies have examined risk factors for developing dyskinesia in PD patients exhibiting wearing-off. Therefore, we investigated the risk factors and impact of dyskinesia in PD patients exhibiting wearing-off.

METHODS

We investigated the risk factors and impact of dyskinesia in a 1-year observational study of Japanese PD patients exhibiting wearing-off (J-FIRST). Risk factors were assessed by logistic regression analyses in patients without dyskinesia at study entry. Mixed-effect models were used to evaluate the impact of dyskinesia on changes in Movement Disorder Society-Unified PD Rating Scale (MDS-UPDRS) Part I and PD Questionnaire (PDQ)-8 scores from one timepoint before dyskinesia was observed.

RESULTS

Of 996 patients analyzed, 450 had dyskinesia at baseline, 133 developed dyskinesia within 1 year, and 413 did not develop dyskinesia. Female sex (odds ratio [95% confidence interval]: 2.636 [1.645-4.223]) and administration of a dopamine agonist (1.840 [1.083-3.126]), a catechol-O-methyltransferase inhibitor (2.044 [1.285-3.250]), or zonisamide (1.869 [1.184-2.950]) were independent risk factors for dyskinesia onset. MDS-UPDRS Part I and PDQ-8 scores increased significantly after the onset of dyskinesia (least-squares mean change [standard error] at 52 weeks: 1.11 [0.52], P = 0.0336; 1.53 [0.48], P = 0.0014; respectively).

CONCLUSION

Female sex and administration of a dopamine agonist, a catechol-O-methyltransferase inhibitor, or zonisamide were risk factors for dyskinesia onset within 1 year in PD patients exhibiting wearing-off. Nonmotor symptoms and quality of life deteriorated after dyskinesia onset.

Writing tremor in Parkinson's disease: frequency and associated clinical features

Action tremor in Parkinson's disease may present in up to 46% of patients, either as postural or kinetic tremor. How action tremor may affect handwriting has been the object of some investigations; however, clinical features of writing tremor in Parkinson's disease are still not well-characterised. One hundred consecutive patients with idiopathic Parkinson's disease were included in the study. Demographic and clinical data were collected through a standardized questionnaire. Patients were assessed for the presence of rest, action and writing tremor in on condition. The effect of a standardised sensory trick (gently touching the wrist of the upper limb manifesting tremor with the contralateral hand) was also investigated in all patients with action tremor. Writing tremor was found in 10% of patients (26% of patients with postural/kinetic tremor, either alone or in combination with rest tremor). Severity of writing tremor did not correlated with that of the other tremor variants and to the other clinical variables. Writing tremor was task-specific in 4/10 patients, no task-specific in 6/10. Sensory trick was effective on writing tremor in two patients but did not improve action tremor in any of the study patients. Results showed that writing tremor in Parkinson's disease is less common than other tremor variants, may be associated with other forms of action tremor, and may sometimes have dystonic features, including task-specificity and sensitivity to sensory trick.

Soft skin-interfaced mechano-acoustic sensors for real-time monitoring and patient feedback on respiratory and swallowing biomechanics

Swallowing is a complex neuromuscular activity regulated by the autonomic nervous system. Millions of adults suffer from dysphagia (impaired or difficulty swallowing), including patients with neurological disorders, head and neck cancer, gastrointestinal diseases, and respiratory disorders. Therapeutic treatments for dysphagia include interventions by speech-language pathologists designed to improve the physiology of the swallowing mechanism by training patients to initiate swallows with sufficient frequency and during the expiratory phase of the breathing cycle. These therapeutic treatments require bulky, expensive equipment to synchronously record swallows and respirations, confined to use in clinical settings. This paper introduces a wireless, wearable technology that enables continuous, mechanoacoustic tracking of respiratory activities and swallows through movements and vibratory processes monitored at the skin surface. Validation studies in healthy adults (n = 67) and patients with dysphagia (n = 4) establish measurement equivalency to existing clinical standard equipment. Additional studies using a differential mode of operation reveal similar performance even during routine daily activities and vigorous exercise. A graphical user interface with real-time data analytics and a separate, optional wireless module support both visual and haptic forms of feedback to facilitate the treatment of patients with dysphagia.

Protective effects of endotoxin tolerance on peripheral lipopolysaccharide-induced neuroinflammation and dopaminergic neuronal injury

CONTEXT

Parkinson's disease is a common chronic neurodegenerative disease characterized by massive loss of dopaminergic neurons in the substantia nigra. Neuroinflammation has been shown to play an important role in the pathogenesis of neurodegenerative diseases such as Parkinson's disease. The role of immune tolerance in neuroinflammation and neurodegenerative diseases induced by peripheral factors is unclear.

OBJECTIVE

This study established a model of endotoxin tolerance to explore the protective effect of endotoxin tolerance on Parkinson-like changes induced by repeated peripheral injections of high-dose LPS, and to explore its inflammatory mechanism.

MATERIALS AND METHODS

In this study, mice were injected intraperitoneally with low dose (0.5 mg/kg) LPS for 4 days to induce endotoxin tolerance (ET). Then, high-dose (1 mg/kg) LPS was injected continuously intraperitoneally for 4 days to induce Parkinson-like changes. Cytokines were detected by enzyme-linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction (qRT-PCR). Activation of microglial cells was detected by protein expression of CD68 and ionized calcium binding adapter molecule 1(Iba-1) by Western blotting and immunofluorescence. Hematoxylin and eosin staining and expression of tyrosine hydroxylase (TH) and dopamine (DA) were used to assess dopaminergic neuronal injury. The open field test and muscle tension test were used to assess behavioral disorders.

RESULTS

As expected, compared with non-ET animals, ET preconditioning significantly reduced the production of inflammatory cytokines in the substantia nigra, inhibited microglial activation, and alleviated the pathological changes of dopaminergic neurons.

CONCLUSIONS

ET may be a promising intervention method for neurodegenerative diseases.HighlightsET was successfully induced by continuous low-dose intraperitoneal LPS injection in mice.ET pretreatment inhibited neuroinflammation in the SN induced by continuous peripheral high doses of LPS.ET pretreatment inhibited continuous peripheral high-dose LPS injection-induced microglial activation in the SN.ET pretreatment decreased LPS-induced functional impairment of dopaminergic neurons.ET reversed the morphological changes of dopaminergic neurons induced by peripheral high-dose LPS.ET pretreatment improved continuous peripheral high-dose LPS injection-induced behavioral impairment.

Approach to Tremor Disorders

Tremor disorders are diverse and complex. Historical clues and examination features play a major role in diagnosing these disorders, but diagnosis can be challenging due to phenotypic overlap. Ancillary testing, such as neuroimaging or laboratory testing, is driven by the history and examination, and should be performed particularly when there are other neurological or systemic manifestations. The pathophysiology of tremor is not entirely understood, but likely involves multiple networks along with the cerebello-thalamo-cortical pathways. Treatment options include medications, botulinum toxin, surgery, and nonpharmacologic interventions utilizing physical and occupational therapies and assistive devices. Further work is needed in developing accurate diagnostic tests and better treatment options for tremor disorders.

Exploring the Role of Orexinergic Neurons in Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disease affecting about 2% of the population. A neuropeptide, orexin, is linked with sleep abnormalities in the parkinsonian patient. This study aimed to review the changes in the orexinergic system in parkinsonian subjects and the effects of orexin. A number of search techniques were used and presumed during the search, including cloud databank searches of PubMed and Medline using title words, keywords, and MeSH terms. PD is characterised by motor dysfunctions (postural instability, rigidity, tremor) and cognitive disorders, sleep-wake abnormalities grouped under non-motor disorders. The Orexinergic system found in the hypothalamus is linked with autonomic function, neuroprotection, learning and memory, and the sleep-wake cycle. Prepro-orexin, a precursor peptide (130 amino acids), gives rise to orexins (Orx-A and Orx-B). Serum orexin level measurement is vital for evaluating several neurological disorders (Alzheimer's disease, Huntington's disease, and PD). Orexinergic neurons are activated by hypoglycemia and ghrelin, while they are restrained by food consumption and leptin. Orexinergic system dysfunctioning was found to be linked with non-motor symptoms (sleep abnormalities) in PD. Orexinergic neuron's behaviour may be either inhibitory or excitatory depending on the environment in which they are present. As well, orexin antagonists are found to improve the abnormal sleep pattern. Since the orexinergic system plays a role in several psychological and neurological disorders, therefore, these disorders can be managed by targeting this system.

Prevalence and Relationship of Rest Tremor and Action Tremor in Parkinson's Disease

Background:

Despite the significance of tremor in Parkinson’s disease (PD) diagnosis, classification, and patient’s quality of life, there is a relative lack of data on prevalence and relationship of different tremor types in PD.

Methods:

The presence of rest tremor (RT) and action tremor (AT; defined as combination of both postural and kinetic tremor) was determined and RT severity was defined using the Movement Disorders Society Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) at baseline in the Progression Marker Initiative (PPMI, n = 423), the Fox Investigation for New Discovery of Biomarkers (BioFIND, n = 118) and the Parkinson’s Disease Biomarkers Program (PDBP, n = 873) cohorts.

Results:

Across baseline data of all three cohorts, RT prevalence (58.2%) was higher than AT prevalence (39.0%). Patients with RT had significantly higher (Chi-square test, p < 0.05) prevalence of AT compared to patients without RT in the PPMI (40.0% versus 30.1%), BioFIND (48.0% versus 40.0%) and PDBP (49.9% versus 21.0%) cohorts. Furthermore, patients with AT had significantly (Student t-test, p < 0.05) higher RT severity that those without AT in PPMI (5.7 ± 5.4 versus 3.9 ± 3.3), BioFIND, 6.4 ± 6.3 versus 3.8 ± 4.4) and PDBP (6.4 ± 6.6 versus 3.7 ± 4.4) cohorts. In the BioFIND cohort, the prevalence of all types of tremor and their combinations significantly decreased from the off-state to on-state.

Discussion:

The RT is the most frequent tremor type and present in more than half of the PD patients. However, AT is also present in nearly one-third of the PD patients. Our results also indicate that RT and AT may have cross-interactions in PD, and that dopaminergic treatment influences both RT and AT.

STN Versus GPi Deep Brain Stimulation for Action and Rest Tremor in Parkinson's Disease

Objective

To investigate the effects of subthalamic nucleus (STN) and globus pallidus internus (GPi), deep brain stimulation (DBS) on individual action tremor/postural tremor (AT) and rest tremor (RT) in Parkinson’s disease (PD). Randomized DBS studies have reported marked benefit in tremor with both GPi and STN and DBS, however, there is a paucity of information available on AT vs RT when separated by the surgical target.

Methods

We retrospectively reviewed the 1-year clinical outcome of PD patients treated with STN and GPi DBS at the University of Florida. We specifically selected patients with moderate to severe AT. Eighty-eight patients (57 STN and 31 GPi) were evaluated at 6 and 12 months for changes in AT and RT in the OFF-medication/ON stimulation state. A comparison of “response” was performed and defined as greater than or equal to a 2-point decrease in tremor score.

Results

STN and GPi DBS both improved AT at 6- and 12-months post-implantation (p < 0.001 and p < 0.001). The STN DBS group experienced a greater improvement in AT at 6 months compared to the GPi group (p = 0.005) but not at the 12 months follow-up (p = 0.301). Both STN and GPi DBS also improved RT at 6- and 12-months post-implantation (p < 0.001 and p < 0.001). There was no difference in RT scores between the two groups at 6 months (p = 0.23) or 12 months (p = 0.74). The STN group had a larger proportion of patients who achieved a “response” in AT at 6 months (p < 0.01), however, this finding was not present at 12 months (p = 0.23). A sub-analysis revealed that in RT, the STN group had a larger percentage of “responders” when followed through 12 months (p < 0.01).

Conclusion

Both STN and GPi DBS reduced PD associated AT and RT at 12 months follow-up. There was no advantage of either brain target in the management of RT or AT. One nuance of the study was that STN DBS was more effective in suppressing AT in the early postoperative period, however, this effect diminished over time. Clinicians should be aware that it may take longer to achieve a similar tremor outcome when utilizing the GPi target.

Clinical Characteristics and Electrophysiological Biomarkers of Parkinson's Disease Developed From Essential Tremor

Background and Objective: Parkinson's disease developed from essential tremor (ET-PD) is a distinct clinical syndrome that is different from essential tremor (ET) and Parkinson's disease (PD). There is currently a lack of research on ET-PD. Tremor characteristics (amplitude and frequency) are primary quantitative indexes for diagnosing and monitoring of tremors. In this study, we aimed to explore specific clinical and electrophysiological biomarkers for the identification of ET-PD. Methods: The study included patients with ET-PD (n = 22), ET (n = 42), and tremor-dominant PD (t-PD, n = 47). We collected demographic data, clinical characteristics (including motor and non-motor symptoms), and tremor analysis. The frequency, amplitude, contracting patterns of resting tremor and postural tremor were collected. The analysis of ET-PD and ET/t-PD was compared. The receiver operating characteristic (ROC) curve was used to analyze the electrophysiological features in distinguishing ET-PD from ET or t-PD. Results: Compared with ET, hyposmia, bradykinesia, rigidity, postural abnormality, and resting tremor were more common in the ET-PD group (P = 0.01, 0.003, 0.001, 0.001, 0.019, respectively). The postural tremor frequencies of the head, upper limbs, and lower limbs were significantly lower in the ET-PD than in the ET (P = 0.007, 0.003, 0.035, respectively), which were the most appropriate variables for distinguishing ET-PD from ET (AUC: 0.775, 0.727, and 0.701, respectively). Compared with t-PD, bradykinesia, rigidity, postural abnormality (both P < 0.001), and resting tremor (P = 0.024) were less common in the ET-PD. The postural tremor amplitudes of the head and upper limbs were significantly higher in the ET-PD than in the t-PD (P = 0.022, 0.001, respectively), which were the most appropriate variables for distinguishing ET-PD from t-PD (AUC: 0.793 and 0.716). Conclusions: Hyposmia and electrophysiological biomarkers (postural tremor frequencies and amplitudes) help early recognition of ET-PD.

Multi-Dimensional, Short-Timescale Quantification of Parkinson's Disease and Essential Tremor Motor Dysfunction

Introduction: Parkinson's disease (PD) is a progressive movement disorder characterized by heterogenous motor dysfunction with fluctuations in severity. Objective, short-timescale characterization of this dysfunction is necessary as therapies become increasingly adaptive.

Objectives: This study aims to characterize a novel, naturalistic, and goal-directed tablet-based task and complementary analysis protocol designed to characterize the motor features of PD.

Methods: A total of 26 patients with PD and without deep brain stimulation (DBS), 20 control subjects, and eight patients with PD and with DBS completed the task. Eight metrics, each designed to capture an aspect of motor dysfunction in PD, were calculated from 1-second, non-overlapping epochs of the raw positional and pressure data captured during task completion. These metrics were used to generate a classifier using a support vector machine (SVM) model to produce a unifying, scalar “motor error score” (MES). The data generated from these patients with PD were compared to same-day standard clinical assessments. Additionally, these data were compared to analogous data generated from a separate group of 12 patients with essential tremor (ET) to assess the task's specificity for different movement disorders. Finally, an SVM model was generated for each of the eight patients with PD and with DBS to differentiate between their motor dysfunction in the “DBS On” and “DBS Off” stimulation states.

Results: The eight metrics calculated from the raw positional and force data captured during task completion were non-redundant. MES generated by the SVM analysis protocol showed a strong correlation with MDS-UPDRS-III scores assigned by movement disorder specialists. Analysis of the relative contributions of each of the eight metrics showed a significant difference between the motor dysfunction of PD and ET. Much of this difference was attributable to the homogenous, tremor-dominant phenotype of ET motor dysfunction. Finally, in individual patients with PD with DBS, task performance and subsequent SVM classification effectively differentiated between the “DBS On” and “DBS Off” stimulation states.

Conclusion: This tablet-based task and analysis protocol correlated strongly with expert clinical assessments of PD motor dysfunction. Additionally, the task showed specificity for PD when compared to ET, another common movement disorder. This specificity was driven by the relative heterogeneity of motor dysfunction of PD compared to ET. Finally, the task was able to distinguish between the “DBS On” and “DBS Off” states within single patients with PD. This task provides temporally-precise and specific information about motor dysfunction in at least two movement disorders that could feasibly correlate to neural activity.

Levodopa Changes Functional Connectivity Patterns in Subregions of the Primary Motor Cortex in Patients With Parkinson's Disease

Background

The primary motor cortex (M1) is a critical node in Parkinson’s disease (PD)-related motor circuitry; however, the functional roles of its subregions are poorly understood. In this study, we investigated changes in the functional connectivity patterns of M1 subregions and their relationships to improved clinical symptoms following levodopa administration.

Methods

Thirty-six PD patients and 37 healthy controls (HCs) were enrolled. A formal levodopa challenge test was conducted in the PD group, and the Unified Parkinson’s Disease Rating Scale motor section (UPDRS-III) was assessed before (off state) and 1 h after administration of levodopa (on state). The PD group underwent resting-state functional magnetic resonance imaging in both off and on states, whereas the HC group was scanned once. We used the Human Brainnetome Atlas template to subdivide M1 into twelve regions of interest (ROIs). Functional connectivity (FC) was compared between PD on and off states [paired t-test, voxel-level p < 0.001, cluster-level p < 0.05, Gaussian random field (GRF) correction] and between patients and HC (two-sample t-test voxel-level p < 0.001, cluster-level p < 0.05). Correlations between ΔFC (differences in FC between PD off and on states) and clinical symptom improvements were examined.

Results

There was decreased FC between the right caudal dorsolateral area 6 and the anterior cingulate gyrus (ACC), the right upper limb region and the left medial dorsal thalamus (mdTHA), as well as increased FC between the left tongue and larynx region and the left medial frontal gyrus. ΔFC between the right caudal dorsolateral area 6 and ACC was positively correlated with improvements in UPDRS-III total scores as well as the rigidity (item 22) and bradykinesia (items 23–26 and 31) subscores. ΔFC between the right upper limb region and left thalamus was positively correlated with improvements in the left upper limb tremor (items 20c and 21b) and postural tremor (item 21b) subscores.

Conclusions

Our results reveal novel information regarding the underlying mechanisms in the motor circuits in the M1 and a promising way to explore the internal function of the M1 in PD patients. Notably, M1 is a potential therapeutic target in PD, and the exploration of its subregions provides a basis and a source of new insights for clinical intervention and precise drug treatment.

Dihydroartemisinin ameliorates LPS-induced neuroinflammation by inhibiting the PI3K/AKT pathway

Neuroinflammation can cause multiple neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). Recent studies have shown that the artemisinin derivative dihydroartemisinin (DHA) can be used as an immunomodulatory, anti-inflammatory and anti-tumor agent. The anti-neuroinflammatory effects of DHA were evaluated in our study, and the underlying mechanisms were explored using the Morris water maze test (MWMT), Open-field test (OFT) and Closed-field test (CFT), Elevated plus maze test (EPMT), Nissl Staining, Immunofluorescence analysis, RT-PCR, and Western Blot. Our results show that DHA significantly inhibits LPS-induced inflammation and attenuates LPS-induced behavioral and memory disorders. 1. Behavioral test results: 1) in the water maze test, the mice in the LPS group showed increased escape latency and length of the movement path on the third day; they also had a decreased number of crossings of the target quadrant after the platform was removed on the 5th day and remained in the target quadrant for less time; 2) in the open- and closed-field experiment, the number of activities and activities in the open-field were significantly reduced; 3) in the elevated cross maze experiment, LPS-treated mice exhibited a significant reduction in the number of times and the time to enter the open arm; the above behavior was reversed after DHA treatment. 2. Nissl staining results: compared with the Control group, the LPS group showed significant damage, and the number of damaged cells in the hippocampal CA1, CA2, CA3 and DG regions was increased; DHA treatment reduced cell damage. 3. RT-PCR results: compared with the Control group, the LPS group showed increased expression of IL-1β and IL-6 but decreased expression after DHA treatment. 4. GFAP fluorescent staining: compared with the control group, the corresponding reactivity of positive cells in the LPS-induced group was increased in the CA1-CA3 and DG regions of the hippocampus; compared with the LPS-induced mice, cells in the LPS + DHA group showed significantly reduced reactivity (GFAP). 5. Western blot results: compared with the Control group, the LPS group showed increased expression of P-PI3K/PI3K, P-AKT/AKT, IL-6 and TNFα and a decreased expression of P-PI3K/PI3K, IL-6, TNF and P-AKT/AKT after DHA treatment. Our findings provide direct evidence for the potential use of DHA in the treatment of neuroinflammatory diseases.

Evolving concepts on bradykinesia

Bradykinesia is one of the cardinal motor symptoms of Parkinson's disease and other parkinsonisms. The various clinical aspects related to bradykinesia and the pathophysiological mechanisms underlying bradykinesia are, however, still unclear. In this article, we review clinical and experimental studies on bradykinesia performed in patients with Parkinson's disease and atypical parkinsonism. We also review studies on animal experiments dealing with pathophysiological aspects of the parkinsonian state. In Parkinson's disease, bradykinesia is characterized by slowness, the reduced amplitude of movement, and sequence effect. These features are also present in atypical parkinsonisms, but the sequence effect is not common. Levodopa therapy improves bradykinesia, but treatment variably affects the bradykinesia features and does not significantly modify the sequence effect. Findings from animal and patients demonstrate the role of the basal ganglia and other interconnected structures, such as the primary motor cortex and cerebellum, as well as the contribution of abnormal sensorimotor processing. Bradykinesia should be interpreted as arising from network dysfunction. A better understanding of bradykinesia pathophysiology will serve as the new starting point for clinical and experimental purposes.

Parkinsonism in essential tremor cases: A clinicopathological study

BACKGROUND

Essential tremor and Parkinson's syndrome are two common movement disorders that may co-occur in some individuals. There is no diagnostic neuropathology for essential tremor, but in PD and other Parkinson's syndrome variants, the neuropathology is well known. The spectrum of Parkinson's syndrome variants associated with essential tremor, their clinical features, and course have not been determined in autopsy-confirmed cases.

OBJECTIVES

To identify: diagnostic features of essential tremor/Parkinson's syndrome, different Parkinson's syndrome variants, and long-term clinical profile in such cases.

METHODS

Patients that had an essential tremor diagnosis and a subsequent clinical or pathological diagnosis of Parkinson's syndrome seen in our clinic during 50 years were included. The diagnosis of parkinsonism was made when bradykinesia, rigidity, and resting tremor were all clinically evident.

RESULTS

Twenty-one cases were included. All the common variants of parkinsonism co-occurred with essential tremor. The most common was PD (67%) followed by PSP. The pathological findings were not predicted clinically in 2 cases that had essential tremor/PD and in all 5 essential tremor/PSP cases.

CONCLUSION

In most essential tremor/Parkinson's syndrome patients, the main motor features of parkinsonism-bradykinesia, rigidity, and resting tremor-were identifiable. All known degenerative Parkinson's syndrome variants co-occurred in essential tremor patients. © 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Clinical progression in Parkinson's disease with features of REM sleep behavior disorder: A population-based longitudinal study

INTRODUCTION

Rapid Eye Movement (REM) sleep behavior disorder (RBD) is characterized by dream enactment and is associated with incidence of neurodegenerative disorders, especially Parkinson's disease (PD). Whether PD with RBD constitutes a distinct subtype with unique progression is unknown. Here, we investigated motor and cognitive symptom progression in patients with self-reported RBD features in adult life.

METHODS

We screened for RBD in a cohort of 776 PD patients whom we ascertained using a population-based strategy. Among participants with at least one follow-up (60%), we compared those with and without probable RBD (pRBD) estimating hazard rate ratios for progression events UPDRS-III≥ 35 and MMSE≤ 24.

RESULTS

Prevalence of pRBD at baseline was 21%. In adjusted Cox regression models among patients with a Postural Instability and Gait Dysfunction (PIGD) phenotype, those with pRBD progressed faster to a UPDRS-III≥ 35 (HR = 1.92, 95% CI = 1.12; 3.27). Also, all patients with pRBD progressed twice as fast to a MMSE score≤ 24 (HR = 2.04, 95% CI = 1.13; 3.69). In sensitivity analyses, using alternative definition of pRBD and accounting for bias due to loss to follow-up results remained similar.

DISCUSSION

Employing data from one of the largest population-based studies of PD, in which movement disorder specialists assessed patients, we confirm evidence that pRBD features are a clinical marker for faster cognitive decline and possibly also motor progression in PD patients, the latter for patients with a PIGD subtype early in disease.

Re-emergent tremor in Parkinson's disease: the effect of dopaminergic treatment

BACKGROUND AND PURPOSE

Patients with Parkinson's disease (PD) with resting tremor may be affected by a tremor that appears after a varying latency while a posture is maintained, a phenomenon referred to as re-emergent tremor (RET). The aim of the study was to evaluate the occurrence and clinical features of RET in patients with PD tested off and on treatment, and to compare the effect of dopaminergic treatment on RET with the effect on resting and action tremor.

METHODS

We consecutively enrolled 100 patients with PD. Patients were clinically evaluated 24 h after withdrawal of therapy (off-treatment phase) and 60 min after therapy administration (on-treatment phase). We collected the demographic and clinical data of patients with PD. The severity of the disease was assessed by means of the Hoehn and Yahr scale and Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale part III. We evaluated the latency, severity and body side affected both off and on treatment in patients with RET.

RESULTS

Re-emergent tremor was present in 24% of the patients with PD off treatment and in 19% of the patients on treatment. Dopaminergic treatment reduced the clinical severity of RET. Dopaminergic treatment increased the number of patients with unilateral RET and reduced the number of those who had bilateral RET. RET and resting tremor responded similarly to dopaminergic treatment, whereas action tremor was less responsive. Patients with RET had milder motor symptoms than patients without RET both off and on treatment.

CONCLUSIONS

Dopaminergic treatment modified RET occurrence, severity and body distribution. Dopaminergic depletion plays a role in the pathophysiology of RET.

The nature of postural tremor in Parkinson disease

OBJECTIVE

To disentangle the different forms of postural tremors in Parkinson disease (PD).

METHODS

In this combined observational and intervention study, we measured resting and postural tremor characteristics in 73 patients with tremulous PD by using EMG of forearm muscles. Patients were measured both "off" medication (overnight withdrawal) and after dispersible levodopa-benserazide 200/50 mg. We performed an automated 2-step cluster analysis on 3 postural tremor characteristics: the frequency difference with resting tremor, the degree of tremor suppression after posturing, and the dopamine response.

RESULTS

The cluster analysis revealed 2 distinct postural tremor phenotypes: 81% had re-emergent tremor (amplitude suppression, frequency difference with resting tremor 0.4 Hz, clear dopamine response) and 19% had pure postural tremor (no amplitude suppression, frequency difference with resting tremor 3.5 Hz, no dopamine response). This finding was manually validated (accuracy of 93%). Pure postural tremor was not associated with clinical signs of essential tremor or dystonia, and it was not influenced by weighing.

CONCLUSION

There are 2 distinct postural tremor phenotypes in PD, which have a different pathophysiology and require different treatment. Re-emergent tremor is a continuation of resting tremor during stable posturing, and it has a dopaminergic basis. Pure postural tremor is a less common type of tremor that is inherent to PD, but has a largely nondopaminergic basis.

Chronic coffee consumption and striatal DAT-SPECT findings in Parkinson's disease

Coffee may interfere with the dopaminergic transmission, and this action would possibly enhance motor activity and exert an antidyskinetic effect in Parkinson's disease (PD). This study aimed to see whether coffee habit could be associated with change in striatal dopamine active transporter (DAT)-single photon emission computed tomography (SPECT) imaging in PD. A total of 83 PD patients (71 current coffee drinkers and 12 never drinkers) underwent a DAT-SPECT study, using [123I]FP-CIT as radionuclide. Socio-demographic and clinical information as well as smoking habit was collected at the time of imaging acquisition. The Unified Parkinson's Disease Rating Scale part III was used to evaluate disease severity. On multivariable analysis, chronic coffee consumption was not associated with any significant change in striatal uptake of the radionuclide. However, the number of years patients drunk coffee was correlated with a significant increase in age at PD onset (p < 0.001). Confirming a previous report, current cigarette smoking was associated with a reduction of radionuclide uptake in putamen and caudate (p < 0.001).

Juglanin ameliorates LPS-induced neuroinflammation in animal models of Parkinson's disease and cell culture via inactivating TLR4/NF-κB pathway

Parkinson's disease (PD) is a common neuro-degenerative disorder, and novel therapeutic targets are required for the treatment of PD. Juglanin is a natural compound extracted from the crude Polygonum aviculare, exhibiting anti-inflammatory, anti-oxidant and anti-cancer activities. In our study, PD in mice was induced by systemic LPS treatment as evidenced by enhanced α-synuclein and reduced tyrosine hydroxylase (TH), which were reversed by juglanin treatment. Moreover, juglanin administration attenuated LPS-caused behavioral and memory impairments and reduced LPS-induced enhancement of neuro-degenerative markers, including amyloid β (Aβ) and p-Tau. Additionally, juglanin ameliorated synaptic functionality through promoting the expression of synaptic markers, such as SYP, PSD-95 and SNAP-25. Toll-like receptor 4 (TLR4) signaling in brain regulates neuroinflammation, contributing to neurodegenerative diseases. Furthermore, LPS induced neuroinflammation through the acceleration of various pro-inflammatory cytokines, including interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), interleukin-18 (IL-18) and Cyclooxygenase-2 (COX-2), via activating TLR4/nuclear factor (NF)-κB pathway in hippocampus of mice and microglia cells. Juglanin significantly reduced LPS-induced production of pro-inflammatory cytokines and blocked TLR4/NF-κB pathway. We also found that LPS-induced astrocytes (AST) activity was prevented by juglanin through down-regulating glial fibrillary acidic protein (GFAP) and Iba1 in vivo and in vitro. Together, our results indicated that juglanin ameliorated neuroinflammation-related memory impairment, and neurodegeneration through impeding TLR4/NF-κB, indicating its potential for PD prevention.

Rest tremor revisited: Parkinson's disease and other disorders

Tremor is the most common movement disorder characterized by a rhythmical, involuntary oscillatory movement of a body part. Since distinct diseases can cause similar tremor manifestations and vice-versa, it is challenging to make an accurate diagnosis. This applies particularly for tremor at rest. This entity was only rarely studied in the past, although a multitude of clinical studies on prevalence and clinical features of tremor in Parkinson's disease (PD), essential tremor and dystonia, have been carried out. Monosymptomatic rest tremor has been further separated from tremor-dominated PD. Rest tremor is also found in dystonic tremor, essential tremor with a rest component, Holmes tremor and a few even rarer conditions. Dopamine transporter imaging and several electrophysiological methods provide additional clues for tremor differential diagnosis. New evidence from neuroimaging and electrophysiological studies has broadened our knowledge on the pathophysiology of Parkinsonian and non-Parkinsonian tremor. Large cohort studies are warranted in future to explore the nature course and biological basis of tremor in common tremor related disorders.

Rest tremor in Parkinson's disease: Body distribution and time of appearance

OBJECTIVE

To assess body distribution and timing of appearance of rest tremor in Parkinson's disease.

METHODS

Information was obtained by a computerized database containing historical information collected at the first visit and data collected during the subsequent follow-up visits. Information on rest tremor developed during the follow-up could be therefore obtained by our own observation in a proportion of patients.

RESULTS

Among 289 patients, rest tremor was reported at disease onset in 65.4% of cases and detected at last follow-up examination in 74.4% of patients. Analysis of patients who did not report rest tremor at disease onset indicated that 26% of such patients (9% in the overall population) manifested rest tremor over the disease course. Rest tremor spread to new sites in 39% of patients who manifested rest tremor at disease onset. Regardless of tremor presentation at disease onset or during the follow-up, upper limb was the most frequent tremor localization. Over the follow-up, rest tremor developed faster in the upper limb than in other body sites. The risk of developing rest tremor during the follow-up was not affected by sex, side of motor symptom onset and site of tremor presentation. However, age of disease onset >63years was associated with an increased risk of rest tremor spread.

CONCLUSIONS

This study provides new information about body distribution and timing of rest tremor appearance during the course of early stages of Parkinson's disease that may help clinicians in patients' counselling.

Re-emergent tremor in Parkinson's disease

INTRODUCTION

Re-emergent tremor (RET) is a postural tremor that appears after a variable delay in patients with Parkinson's disease (PD). The aim of the present study was to evaluate the occurrence and the clinical characteristics of RET in a population of patients with PD.

METHODS

We consecutively assessed 210 patients with PD. We collected the patients' demographic and clinical data. RET was clinically characterized in terms of latency, severity and body side affected. We also investigated a possible relationship with motor and non-motor symptoms and differences in the clinical features in patients with and without RET.

RESULTS

RET was present in 42/210 patients. The mean latency of RET was 9.20 ± 6.8 seconds. Mean severity was 2.4 ± 1.9. RET was unilateral in 21 patients. Patients with RET had less severe speech, posture and gait disorders and upper limb and global bradykinesia than patients without RET. Similar findings were observed when we compared patients with RET with patients with tremor at rest associated with action tremor, patients with isolated action tremor and patients with no tremor. By contrast, patients with RET tremor did not clinically differ from those with isolated tremor at rest.

CONCLUSION

Our results suggest that patients with RET and patients with isolated tremor at rest represent the same clinical subtype, whereas patients with action tremor (whether isolated or associated with tremor at rest) might belong to a distinct subtype that is clinically worse. Patients with RET represents a benign subtype of PD, even within the tremor-dominant phenotype.

Smoking in Patients with Parkinson's Disease: preliminary striatal DaT-SPECT findings

OBJECTIVE

To assess whether cigarette smoking interferes with dopaminergic transmission in current- and never-smoking patients with Parkinson's disease.

MATERIALS AND METHODS

Striatal [123I]FP-CIT single photon emission computed tomography was performed in 67 patients with Parkinson's disease (35 women and 32 men aging 60.8 ± 10.1 years and staging 1.76 ± 0.5 on the Hoehn and Yahr scale). At study time, there were 13 current-smokers and 54 never-smokers.

RESULTS

Current-smokers showed a significantly lower putamen/occipital [123I]FP-CIT ratio and a non-significant trend to a lower caudate/occipital [123I]FP-CIT ratio uptake. Current-smokers were also characterized by a lower off UPDRS-III motor score. A logistic regression analysis adjusted for age, sex, disease duration, Hoehn and Yahr staging, and medication indicated a significant lower [123I]FP-CIT uptake not only in the putamen (odds ratio, 0.1; 95% confidence interval, 0.01 to 0.65; P = 0.02) but also in the caudate (odds ratio, 0.2; 95% confidence interval, 0.04 to 0.71; P = 0.015) as well as a lower UPDRS-III motor score (odds ratio, 0.9; 95% confidence interval, 0.81 to 0.99; P = 0.04) in current-smokers.

CONCLUSIONS

The lower [123I]FP-CIT uptake together with the lower UPDRS-III motor score observed in our current-smokers patients with Parkinson's disease (even taking into account variables that are probably expression of dopaminergic neuron decline and treatment) would support an effect of smoking on dopaminergic synaptic mechanisms.

Tremor entities and their classification: an update

PURPOSE OF REVIEW

This review focuses on important new findings in the field of tremor and illustrates the consequences for the current definition and classification of tremor.

RECENT FINDINGS

Since 1998 when the consensus criteria for tremor were proposed, new variants of tremors and new diagnostic methods were discovered that have changed particularly the concepts of essential tremor and dystonic tremor. Accumulating evidence exists that essential tremor is not a single entity rather different conditions that share the common symptom action tremor without other major abnormalities. Tremor is a common feature in patients with adult-onset focal dystonia and may involve several different body parts and forms of tremor. Recent advances, in particular, in the field of genetics, suggest that dystonic tremor may even be present without overt dystonia. Monosymptomatic asymmetric rest and postural tremor has been further delineated, and apart from tremor-dominant Parkinson's disease, there are several rare conditions including rest and action tremor with normal dopamine transporter imaging (scans without evidence of dopaminergic deficit) and essential tremor with tremor at rest.

SUMMARY

Increasing knowledge in the last decades changed the view on tremors and highlights several caveats in the current tremor classification. Given the ambiguous assignment between tremor phenomenology and tremor etiology, a more cautious definition of tremors on the basis of clinical assessment data is needed.