Background Essential tremor (ET) is a prevalent movement disorder affecting the upper limbs, yet the neural basis of hand-specific motor dysfunction remains incompletely understood. Most fMRI studies have not explicitly addressed lateralization of tremor-related brain activity. This study used both multivariate pattern analysis (MVPA) and univariate general linear modeling (GLM) to characterize brain network engagement during right- and left-hand movements in ET.Methods Eighteen right-handed ET patients and 18 age-matched healthy volunteers performed alternating right- and left-hand finger-tapping tasks during fMRI. Whole-brain GLM assessed subject-level BOLD activation, and searchlight MVPA quantified subject-level local decoding performance. Group-level analyses compared activation and decoding patterns between groups, and associations with hand-specific tremor severity were examined within the ET group.Results During right-hand finger-tapping, ET patients exhibited bilateral motor network engagement. GLM revealed reduced BOLD activity in the thalami and right supramarginal gyrus, while MVPA showed decreased decoding in the right supramarginal gyrus. In left-hand finger-tapping, a more lateralized pattern emerged, with diminished activation and decoding performance in the right thalamus and right supramarginal gyrus. Left cerebellar involvement differed between tasks and showed putative compensatory engagement, and right insular activity was associated with tremor severity during task performance. Overall, cortical alterations were predominantly right lateralized across both hands.Conclusions ET is associated with hand-specific differences in task-related network engagement, involving cerebello-thalamo-cortical and higher-order sensorimotor regions. Right-hand movements engaged more bilateral motor circuits, whereas left-hand movements showed relatively stronger right-hemispheric involvement, suggesting lateralized task-related network alterations in ET.

BACKGROUND:Myoclonus is a brief shock-like, involuntary movement, which can be distinguished in physiologic, essential, epileptic, and symptomatic, according to its etiology. Physiologic myoclonus typically occurs in healthy people without disability or progression. OBJECTIVES:We suggest a new nosological entity in the physiologic group: "benign idiopathic myoclonus." METHODS:We present a cohort of patients with isolated adolescent-onset, distal limb myoclonus at rest and during action, in absence of a known cause and disabling progression, who underwent both clinical and neurophysiological examination in our tertiary Movement Disorders Expertise Center Groningen. RESULTS:Fifteen patients (4 men [26.7%]; age at onset, 18.1 ± 3.6 years; disease-duration, 5.3 ± 3.7 years) were assessed. Neurophysiological examinations, including electromyography (EMG) (n = 14), somatosensory evoked potentials (SEPs, n = 4); electroencephalography (EEG)-EMG with back-averaging (BA, n = 11) and cortico-muscular coherence (CMC, n = 10), confirmed the clinical diagnosis of myoclonus in all patients. Mean EMG burst duration was 62.6 ± 13.7 ms and a cortical origin of myoclonus was demonstrated in six cases (40%). No genetic causes were found. Follow-up at 0.5 to 8 years depicted clinically stable conditions in eight patients (61.5%), complete remission in four (30.8%), whereas one patient (7.7%) reported slight progression. CONCLUSIONS:We suggest a new phenotype of physiologic myoclonus, which might be called "benign idiopathic myoclonus." It is characterized by distal myoclonus with onset during adolescence and benign course, without requiring treatment. Clinically and neurophysiologically these jerky movements were compatible with cortical myoclonus in some patients. We were unable to establish any genetic causes in explored cases. This phenotype might represent a particular subgroup of physiologic myoclonus, to be substantiated in multicenter cohorts.

INTRODUCTION:The Next Move in Movement Disorders (NEMO) is a cross-sectional study aimed to propose innovative strategies for the classification and management of Hyperkinetic Movement Disorders (HMDs). The clinical visibility of essential tremor, dystonia, cortical myoclonus and myoclonus-dystonia through standardized video procedure is assessed here, with the aim to evaluate the best tasks for eliciting the clinical signs of each specific phenotype. METHODS:Eighty-four patients with HMDs were enrolled: 19 affected by essential tremor, 21 by dystonia, 18 by myoclonus and 26 by myoclonus-dystonia. The video protocol included 21 tasks based on the most common clinical rating scales for HMDs. A total of 1735 videos were rated by three independent movement disorders specialists, assessing the degree of visibility of each phenotype on a five-point rating scale. RESULTS:Near perfect interrater agreement regarding the visibility of each disorder was reached for essential tremor (ICC 0.87), dystonia (ICC 0.85) and myoclonus-dystonia (ICC 0.81) phenotypes, while substantial agreement was observed for myoclonus (ICC 0.75). The best tasks to increase the visibility for all included phenotypes were 1) pronated outstretched arms and hands with palms facing down, 2) the same task during the serial seven subtraction task, and 3) pronated outstretched arms and extended wrists with palms forward. CONCLUSIONS:Our findings using a standardized video procedure demonstrate that three clinical tasks are satisfactory to elicit all the phenotypes. The accurate choice of specific clinical tasks could help clinicians and researchers to reduce the number of tasks needed in the classification of the different HMD phenotypes and to develop a computer-aided classification tool for HMDs including clinical data, video settings and neurophysiological parameters.

BACKGROUND:Pregnancy after a Parkinson's diagnosis presents complex challenges. Due to the paucity of literature, there is no evidence-based guidelines and protocols for preconception care, management of pregnancy, childbirth and the postpartum period in women with early-onset Parkinson's disease (PD). Decision-making can be fraught with uncertainty for both patients and healthcare providers. OBJECTIVES:This review is aimed to provide pragmatic advice to help guide women with PD before, during and after pregnancy, and to address key gaps in the existing literature. METHODS:An interdisciplinary working group of movement disorder specialists, obstetricians, perinatal neuropsychiatrists, physiotherapist, pharmacist and individuals with lived experiences collaborated to assess published evidence. In areas lacking robust data, recommendations were derived from case studies, registries, clinical and personal expertise. RESULTS:Key recommendations include: Motor Symptom Management: Levodopa remains the safest treatment during the perinatal period. Monotherapy is preferred over polypharmacy. Non-Motor Symptom Management: Some non-motor symptoms are particularly common in this patient group and warrant individualized care. Preconception Considerations: Proactive planning about medical management should be done before conception. Genetic counseling and screening should be provided if desired. Peripartum and Postpartum Considerations: The decision regarding mode of delivery should be based upon women's birth plans and obstetric indications. Breastfeeding should be cautiously considered depending on the need for pharmacological treatment. CONCLUSIONS:This article provides a framework for managing PD before, during and after pregnancy. Collaborative efforts and ongoing registries like PregSpark* will be important to develop robust, evidence-based guidelines in this unique population.

Atypical parkinsonian syndromes (APs) are characterized by parkinsonian features combined with additional motor and non-motor signs and symptoms. Neurophysiological studies have contributed to clarifying differences and similarities between APs and idiopathic Parkinson's disease (PD) and to unravel specific pathophysiological features of APs. A comprehensive and updated evaluation of the potential clinical utility of the available neurophysiological tools in APs is, however, currently needed. The Neurophysiology Study Group of the International Parkinson and Movement Disorder Society reviewed previously published neurophysiological studies including those based on electromyography, electroencephalography, and evoked potentials, transcranial magnetic stimulation and kinematics, in most relevant APs, including progressive supranuclear palsy, multiple system atrophy, corticobasal syndrome, Lewy body dementia, fronto-temporal dementia, vascular parkinsonism, normal pressure hydrocephalus, and drug-induced parkinsonism. Following a critical narrative review of all the available information for each AP, the study group examined the most relevant pathophysiological advances achieved in the field owing to the application of specific neurophysiological tools. Furthermore, the review includes statements regarding the potential role in a research context (ie, pathophysiological investigation) as well as in the clinical setting (ie, clinical utility) of each neurophysiological technique, through an estimation of the corresponding levels of evidence, based on the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system. Finally, an example of a possible stepwise approach based on the sequential application of specific neurophysiological techniques for better supporting the clinical differential diagnosis of PD and APs is proposed. © 2025 International Parkinson and Movement Disorder Society.

L-dopa (LD) effects on visually guided saccades (VGS) have been poorly investigated in de novo Parkinson’s disease (PD) patients through a standardized acute challenge test. To assess the acute saccadic effects of LD as well as possible different patterns of VGS response to LD in a consistent population of de novo PD. VGS were assessed among de novo PD at baseline and 2 h after the administration of LD/carbidopa 250/25 mg. Baseline instrumental assessments were compared with healthy controls (HCs). Thirty-two de novo PD and 17 HCs were enrolled. PD patients showed lower upward velocities and amplitude than HCs, improving after LD administration. Two subgroups were identified among PD patients based on percent improvement or worsening of the most significant changing VGS parameter after LD administration: Group A (19 patients, showing improvement) and B (13 patients, showing worsening). Group A had at baseline reduced vertical, especially downward, velocities, gain and amplitude compared to Group B, with a significant improvement after LD. Conversely, in Group B, an LD-induced worsening effect on both horizontal and vertical VGS parameters was found. Comparing the two identified groups based on clinical–demographic characteristics, higher prevalence of female sex was found in Group B. De novo PD patients presented prominent vertical VGS impairment which improved acutely after LD administration. Different patterns of acute saccadic responses to LD were also shown, suggesting a possible role of VGS in PD phenotyping.

Parkinson’s Disease (PD) body-first subtype is characterized by prodromal autonomic symptoms and REM sleep behavior disorder (RBD), symmetric dopaminergic degeneration, and increased risk of dementia. On the other hand, the PD brain-first subtype has fewer non-motor symptoms and a milder motor phenotype. The temporal relationship between RBD onset and motor symptoms onset may differentiate these two subtypes. We aimed to investigate electrocortical differences between brain-first and body-first PD patients. PD patients with an available routinely collected EEG were retrospectively selected. RBD was diagnosed using the RBD screening questionnaire (≥ 6). According to the onset of RBD patients were classified into PD-RBDpre (RBD onset before motor symptoms) and PD-RBDpost (RBD onset after motor symptoms). Patients without RBD were classified as PD-RBD-. Presence of Mild Cognitive Impairment (MCI) was diagnosed according to the MDS criteria. EEG Spectral analysis was performed in resting state by computing the Power Spectral Density (PSD) of site-specific signal epochs for the common frequency bands (delta, theta, alpha, beta). Thirty-eight PD-RBD-, 14 PD-RBDpre and 31 PD-RBDpost patients were recruited. Comparing both global and site-specific absolute values, we found a significant trend toward beta band reduction going from PD-RBD-, PD-RBDpost and PD-RBDpre. No significant differences were found between PD-RBDpost and PD-RBD- patients. PD-RBDpre patients may represent a different subset of patients as compared to patients without RBD, while patients with later onset have intermediate EEG spectral features. Quantitative EEG may provide new hints in PD subtyping.

Hypokinetic movement disorders encompass a group of clinically similar diseases that present challenges in discrimination during neurological examinations. Characterizing a specific hypokinetic disorder is necessary for the diagnosis and treatment in daily clinical practice. Neurophysiological tools, such as electromyography (EMG) combined with accelerometry, motor-evoked potentials (MEPs), electroencephalographic recording (EEG), Bereitschaftspotential (BP), auditory-evoked cognitive potential (P300), blink reflex (BR), and R2 blink reflex recovery cycle (R2BRRC), are useful in the differential diagnosis of movement disorders due to the common clinical features. However, neurophysiological assessments of movement disorders, especially hypokinetic diseases, are currently underutilized in clinical practice as compared to a few decades ago. This review aims to summarize practical insights gleaned from reported studies over the past 5 years (i.e., 2019 – 2023) regarding neurophysiological assessments of hypokinetic movement disorders, emphasizing the importance of their routine application. In particular, the methodology of the electrophysiologic evaluations pertaining to hypokinetic movement disorders is assessed. Moreover, a practical approach for the differential diagnosis of similar movement disorder syndromes based on specific neurophysiological features is proposed. Collectively, this review of the most recent neurophysiological implications in hypokinetic movement disorders highlights the practicality of these methods. Despite the advancement of other diagnostic techniques (e.g., neuroradiological methods), neurophysiological assessments may be a promising tool for clinical diagnoses, due to their high accuracy and ability to categorize and manage movement disorders (e.g., hypokinetic movement disorders) in daily clinical practice.

Neurodegenerative diseases are common causes of impaired mobility and cognition in the elderly. Among them, tauopathies and alpha-synucleinopathies were considered. The neurodegenerative processes and relative differential diagnosis were addressed through a qEEG non-linear analytic method. Study aims were to test accuracy of the power law exponent beta applied to EEG in differentiating neurodegenerative diseases and to explore differences in neuronal connectivity among different neurodegenerative processes based on beta. N = 230 patients with a diagnosis of tauopathy or alpha-synucleinopathy and at least one artifact-free EEG recording were selected. Periodogram was applied to EEG signal epochs from continuous recordings. Power law exponent beta was determined by the slope of the signal power spectrum versus frequency in logarithmic scale. A data-driven clustering based on beta values was performed to identify independent subgroups. Data-driven clustering based on beta differentiated tauopathies (overall lower beta values) from alpha-synucleinopathies (higher beta values) with high sensitivity and specificity. Tauopathies also presented lower values in the correlation coefficients matrix among frontal sites of recording. In conclusion, significant differences in beta values were found between tauopathies and alpha-synucleinopathies. Hence, beta is proposed as a possible biomarker of differential diagnosis and neuronal connectivity.

BackgroundDifferential diagnosis between idiopathic normal pressure hydrocephalus (iNPH) associated with parkinsonism (iNPH-P) and Parkinson's disease (PD) may prove difficult when evaluating patients with early parkinsonism. The objective of this study was to evaluate differences in mobility during standardized tasks between iNPH-P and PD. MethodsWe selected 21 iNPH-P and 21 pharmacologically untreated PD patients. They all performed the instrumented Timed Up and Go test at the time of diagnosis. ResultsTurning tasks showed longer duration and lower speed in iNPH-P than in PD. Vertical variation in acceleration during the sit-to-stand phase was lower in iNPH-P patients, whereas the duration of the stand-to-sit phase was longer. On walking, iNPH-P showed smaller stride length and a longer gait cycle duration. In multivariate analysis adjusting for age and cognitive status as potential confounders, average angular speed on turning before sitting was the discriminating parameter between the two groups. ConclusionsPatients with iNPH-P showed specific abnormal mobility performances with respect to untreated PD, specifically during the turning-to-sitting transition.

Long‐duration response (LDR) to levodopa and motor learning could be involved in changes in neuroplasticity of cortical excitability in Parkinson's disease (PD). P300, motor evoked potentials (MEPs), and Bereitschaftspotential (BP) are neurophysiological surrogate markers of neuroplasticity.

Ocular abnormalities in myasthenia gravis (MG) are characterized by severely limited movements and rapid saccades. Data about eye motility of MG patients whose ocular movements are apparently normal are lacking. Our study assessed the eye movement parameters in MG patients without clinical eye motility dysfunctions and investigated the effects of neostigmine administration on the eye motility in these patients. In this longitudinal study, we screened all patients diagnosed with MG referring to the Neurologic Clinic of the University of Catania between October 1, 2019, and June 30, 2021. Ten age- and sex-matched healthy controls were enrolled. Patients underwent eye movement recording using the EyeLink1000 Plus® eye tracker at baseline and after 90 min from the intramuscular administration of neostigmine (0.5 mg). A total of 14 MG patients with no clinical signs of ocular motor dysfunction (64.3

Background: Essential tremor (ET) represents a heterogeneous condition which may overlap with Parkinson disease (PD) even at early stages, by sharing some subtle clinical aspects. Longstanding ET demonstrated also higher risk of developing PD, especially with a Tremor-dominant (TD-PD) phenotype. Therefore, differential diagnosis between ET and early PD could be quite challenging. Optical coherence tomography (OCT) has been recognized as a reliable tool to assess the retina as a proxy of neurodegeneration. We aimed to explore the possible role of retinal assessment in differential diagnosis between ET and early PD. Methods: Macular layers and peripapillary retinal nerve fiber layer (RNFL) thickness among ET, early PD, and healthy controls (HCs) were assessed using OCT. Results: Forty-two eyes from 23 ET, 41 eyes from 21 early PD, and 33 eyes from 17 HCs were analyzed. Macular RNFL, ganglion cell layer, inner plexiform layer, and inner nuclear layer were thinner in PD as compared with ET and even more in HCs. Differences between ET and PD were more evident when considering the TD-PD subgroup, especially for RNFL. Among ET patients, thickness of the inner macular layers showed negative linear relationship with both age at onset and disease duration. Peripapillary temporal quadrant thinning was found in ET compared with HCs. Conclusions: Macular inner retina was thinner in patients with ET and early PD compared with HCs. These findings suggest that the retinal assessment may have a utility in the differential diagnosis between ET and PD.