Rethinking the neurophysiological concept of cortical myoclonus.

Cortical myoclonus is thought to result from abnormal electrical discharges arising in the sensorimotor cortex. Given the ease of recording of cortical discharges, electrophysiological features of cortical myoclonus have been better characterized than those of subcortical forms, and electrophysiological criteria for cortical myoclonus have been proposed. These include the presence of giant somatosensory evoked potentials, enhanced long-latency reflexes, electroencephalographic discharges time-locked to individual myoclonic jerks and significant cortico-muscular connectivity.

A Reflection on Motor Overflow, Mirror Phenomena, Synkinesia and Entrainment.

In patients with movement disorders, voluntary movements can sometimes be accompanied by unintentional muscle contractions in other body regions. In this review, we discuss clinical and pathophysiological aspects of several motor phenomena including mirror movements, dystonic overflow, synkinesia, entrainment and mirror dystonia, focusing on their similarities and differences. These phenomena share some common clinical and pathophysiological features, which often leads to confusion in their definition.

Operationalizing the centiloid scale for [F]florbetapir PET studies on PET/MRI.

Introduction: The Centiloid scale aims to harmonize amyloid beta (Aβ) positron emission tomography (PET) measures across different analysis methods. As Centiloids were created using PET/computerized tomography (CT) data and are influenced by scanner differences, we investigated the Centiloid transformation with data from Insight 46 acquired with PET/magnetic resonanceimaging (MRI).

Methods: We transformed standardized uptake value ratios (SUVRs) from 432 florbetapir PET/MRI scans processed using whole cerebellum (WC) and white matter (WM) references, with and without partial volume correction.

Childhood-Onset Choreo-Dystonia Due to a Recurrent Novel Homozygous Nonsense Variant: Case Series and Literature Review.

Background: Biallelic variants in were linked to isolated dystonia (formerly DYT2) in 2015. Since then, the clinical spectrum of -related disorder has expanded up to including a complex syndrome encompassing neurodevelopmental delay, generalized dystonia with bulbar involvement, and infantile seizures.

Cases: We report four individuals with a new phenotype of childhood-onset choreo-dystonia belonging to two unrelated Iranian pedigrees and harboring a novel homozygous nonsense pathogenic variant NM_002143.

Biallelic Loss-of-Function Variants Cause a Wide Phenotypic Spectrum from Leigh/Leigh-Like Syndrome to Isolated Optic Atrophy.

Background: Biallelic loss-of-function variants have hitherto been linked to mitochondrial complex I deficiency presenting with heterogeneous clinical and radiological features in nine cases only.

Objectives: To fully characterize, both phenotypically and genotypically, -related mitochondrial disease.

Methods: We collected data from cases identified by screening genetic databases of several laboratories worldwide and systematically reviewed the literature.

When it is not primary progressive aphasia: A scoping review of spoken language impairment in other neurodegenerative dementias.

Background: Progressive difficulties with spoken language occur across the spectrum of degenerative dementia. When not a primary presenting and dominant symptom, language difficulties may be overlooked in favor of more prominent cognitive, behavior, or motor deficits. The aim of this scoping review is to examine the extent and nature of the research evidence describing (1) the spoken language impairments found in non-language led dementias, (2) their impact on everyday living, and (3) the reported language interventions.

Retinal phenotyping of variants of Alzheimer's disease using ultra-widefield retinal images.

Background: Posterior cortical atrophy (PCA) is the most common atypical variant of Alzheimer's disease (AD). Changes associated with PCA in the brain affect the visual cortex, but little is known about retinal changes in PCA. In this study, we explored retinal phenotypic variations in typical AD (tAD) and PCA.

Current advances in digital cognitive assessment for preclinical Alzheimer's disease.

There is a pressing need to capture and track subtle cognitive change at the preclinical stage of Alzheimer's disease (AD) rapidly, cost-effectively, and with high sensitivity. Concurrently, the landscape of digital cognitive assessment is rapidly evolving as technology advances, older adult tech-adoption increases, and external events (i.e.

Factors Associated with Health-Related Quality of Life in Late-Stage Parkinson's Disease.

Background: There is limited knowledge on health-related quality of life (HRQoL) in late-stage Parkinson's disease (PD).

Objective: To assess factors associated with HRQoL in patients with late-stage PD, with a focus on health care provision.

Methods: The Care of Late Stage Parkinsonism (CLaSP) project is the largest study on late-stage PD to date.

Spastic paraplegia preceding -related familial Alzheimer's disease.

Introduction: We investigated the frequency, neuropathology, and phenotypic characteristics of spastic paraplegia (SP) that precedes dementia in presenilin 1 () related familial Alzheimer's disease (AD).

Methods: We performed whole exome sequencing (WES) in 60 probands with hereditary spastic paraplegia (HSP) phenotype that was negative for variants in known HSP-related genes. Where mutation was identified, brain biopsy was performed.

Brainstem Reflexes in Idiopathic Cervical Dystonia: Does Medullary Dysfunction Play a Role?

Background: Neurophysiological markers in dystonia have so far not been sistematically applied in clinical practice due to limited reproducibility of results and low correlations with clinical findings. Exceptions might be represented by the blink reflex (BR), including its recovery cycle (BRRC) and the trigemino-cervical reflex (TCR) which, compared to other neurophysiological methods, have shown more consistent alterations in cervical dystonia (CD). However, a comparison between the two techniques, and their possible correlation with disease symptoms, have not been thoroughly investigated.

Exploring Interrater Disagreement on Essential Tremor Using a Standardized Tremor Elements Assessment.

Background: Patients with upper limb action tremor frequently exhibit additional neurological signs of uncertain significance. Clinicians vary in their interpretation, and interrater agreement on the final diagnosis is poor.

Objectives: A new clinical tool for assessing the presence or absence of clinical signs that are important in axis-1 classification of tremor patients is introduced: the Standardized Tremor Elements Assessment (STEA).

Disease Onset in Huntington's Disease: When Is the Conversion?

Background: Determination of disease onset in Huntington's disease is made by clinical experience. The diagnostic confidence level is an assessment regarding the certainty about the clinical diagnosis based on motor signs. A level of 4 means the rater has ≥99% confidence motor abnormalities are unequivocal signs of disease.

Challenges in Clinicogenetic Correlations: One Gene - Many Phenotypes.

Background: Progress in genetics - particularly the advent of next-generation sequencing (NGS) - has enabled an unparalleled gene discovery and revealed unmatched complexity of genotype-phenotype correlations in movement disorders. Among other things, it has emerged that mutations in one and the same gene can cause multiple, often markedly different phenotypes. Consequently, movement disorder specialists have increasingly experienced challenges in clinicogenetic correlations.

Prevalence of Non-Motor Symptoms and Non-Motor Fluctuations in Parkinson's Disease Using the MDS-NMS.

Background: Non-motor symptoms (NMS) are frequent in Parkinson's disease (PD).

Objectives: To estimate the prevalence of NMS and of non-motor fluctuations (NMF) using the Movement Disorders Society-Non-Motor Rating Scale (MDS-NMS) and other scales assessing NMS, and their relationship with sex and PD severity.

Methods: Cross-sectional study with a sample of 402 PD patients.

Analyzing large Alzheimer's disease cognitive datasets: Considerations and challenges.

Recent data-sharing initiatives of clinical and preclinical Alzheimer's disease (AD) have led to a growing number of non-clinical researchers analyzing these datasets using modern data-driven computational methods. Cognitive tests are key components of such datasets, representing the principal clinical tool to establish phenotypes and monitor symptomatic progression. Despite the potential of computational analyses in complementing the clinical understanding of AD, the characteristics and multifactorial nature of cognitive tests are often unfamiliar to computational researchers and other non-specialist audiences.