Quantum-well states at the surface of a heavy-fermion superconductor.

Two-dimensional electronic states at surfaces are often observed in simple wide-band metals such as Cu or Ag (refs. 1-4). Confinement by closed geometries at the nanometre scale, such as surface terraces, leads to quantized energy levels formed from the surface band, in stark contrast to the continuous energy dependence of bulk electron bands2,5-10. Their energy-level separation is typically hundreds of meV (refs. 3,6,11). In a distinct class of materials, strong electronic correlations lead to so-called heavy fermions with a strongly reduced bandwidth and exotic bulk ground states12,13. Quantum-well states in two-dimensional heavy fermions (2DHFs) remain, however, notoriously difficult to observe because of their tiny energy separation. Here we use millikelvin scanning tunnelling microscopy (STM) to study atomically flat terraces on U-terminated surfaces of the heavy-fermion superconductor URu2Si2, which exhibits a mysterious hidden-order (HO) state below 17.5 K (ref. 14). We observe 2DHFs made of 5f electrons with an effective mass 17 times the free electron mass. The 2DHFs form quantized states separated by a fraction of a meV and their level width is set by the interaction with correlated bulk states. Edge states on steps between terraces appear along one of the two in-plane directions, suggesting electronic symmetry breaking at the surface. Our results propose a new route to realize quantum-well states in strongly correlated quantum materials and to explore how these connect to the electronic environment.

Spoken Language Alterations can Predict Phenoconversion in Isolated Rapid Eye Movement Sleep Behavior Disorder: A Multicenter Study.

OBJECTIVE: This study assessed the relationship between speech and language impairment and outcome in a multicenter cohort of isolated/idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD). METHODS: Patients with iRBD from 7 centers speaking Czech, English, German, French, and Italian languages underwent a detailed speech assessment at baseline. Story-tale narratives were transcribed and linguistically annotated using fully automated methods based on automatic speech recognition and natural language processing algorithms, leading to the 3 distinctive linguistic and 2 acoustic patterns of language deterioration and associated composite indexes of their overall severity. Patients were then prospectively followed and received assessments for parkinsonism or dementia during follow-up. The Cox proportional hazard was performed to evaluate the predictive value of language patterns for phenoconversion over a follow-up period of 5 years. RESULTS: Of 180 patients free of parkinsonism or dementia, 156 provided follow-up information. After a mean follow-up of 2.7 years, 42 (26.9%) patients developed neurodegenerative disease. Patients with higher severity of linguistic abnormalities (hazard ratio [HR = 2.35]) and acoustic abnormalities (HR = 1.92) were more likely to develop a defined neurodegenerative disease, with converters having lower content richness (HR = 1.74), slower articulation rate (HR = 1.58), and prolonged pauses (HR = 1.46). Dementia-first (n = 16) and parkinsonism-first with mild cognitive impairment (n = 9) converters had higher severity of linguistic abnormalities than parkinsonism-first with normal cognition converters (n = 17). INTERPRETATION: Automated language analysis might provide a predictor of phenoconversion from iRBD into synucleinopathy subtypes with cognitive impairment, and thus can be used to stratify patients for neuroprotective trials. ANN NEUROL 2024;95:530-543.

Speech biomarkers in Huntington's disease: A cross-sectional study in pre-symptomatic, prodromal and early manifest stages.

BACKGROUND AND PURPOSE: Motor speech alterations are a prominent feature of clinically manifest Huntington's disease (HD). Objective acoustic analysis of speech can quantify speech alterations. It is currently unknown, however, at what stage of HD speech alterations can be reliably detected. We aimed to explore the patterns and extent of speech alterations using objective acoustic analysis in HD and to assess correlations with both rater-assessed phenotypical features and biological determinants of HD. METHODS: Speech samples were acquired from 44 premanifest (29 pre-symptomatic and 15 prodromal) and 25 manifest HD gene expansion carriers, and 25 matched healthy controls. A quantitative automated acoustic analysis of 10 speech dimensions was performed. RESULTS: Automated speech analysis allowed us to differentiate between participants with HD and controls, with areas under the curve of 0.74 for pre-symptomatic, 0.92 for prodromal, and 0.97 for manifest stages. In addition to irregular alternating motion rates and prolonged pauses seen only in manifest HD, both prodromal and manifest HD displayed slowed articulation rate, slowed alternating motion rates, increased loudness variability, and unstable steady-state position of articulators. In participants with premanifest HD, speech alteration severity was associated with cognitive slowing (r = -0.52, p < 0.001) and the extent of bradykinesia (r = 0.43, p = 0.004). Speech alterations correlated with a measure of exposure to mutant gene products (CAG-age-product score; r = 0.60, p < 0.001). CONCLUSION: Speech abnormalities in HD are associated with other motor and cognitive deficits and are measurable already in premanifest stages of HD. Therefore, automated speech analysis might represent a quantitative HD biomarker with potential for assessing disease progression.

Speech Biomarkers in Rapid Eye Movement Sleep Behavior Disorder and Parkinson Disease.

OBJECTIVE: This multilanguage study used simple speech recording and high-end pattern analysis to provide sensitive and reliable noninvasive biomarkers of prodromal versus manifest α-synucleinopathy in patients with idiopathic rapid eye movement sleep behavior disorder (iRBD) and early-stage Parkinson disease (PD). METHODS: We performed a multicenter study across the Czech, English, German, French, and Italian languages at 7 centers in Europe and North America. A total of 448 participants (337 males), including 150 with iRBD (mean duration of iRBD across language groups 0.5-3.4 years), 149 with PD (mean duration of disease across language groups 1.7-2.5 years), and 149 healthy controls were recorded; 350 of the participants completed the 12-month follow-up. We developed a fully automated acoustic quantitative assessment approach for the 7 distinctive patterns of hypokinetic dysarthria. RESULTS: No differences in language that impacted clinical parkinsonian phenotypes were found. Compared with the controls, we found significant abnormalities of an overall acoustic speech severity measure via composite dysarthria index for both iRBD (p = 0.002) and PD (p < 0.001). However, only PD (p < 0.001) was perceptually distinct in a blinded subjective analysis. We found significant group differences between PD and controls for monopitch (p < 0.001), prolonged pauses (p < 0.001), and imprecise consonants (p = 0.03); only monopitch was able to differentiate iRBD patients from controls (p = 0.004). At the 12-month follow-up, a slight progression of overall acoustic speech impairment was noted for the iRBD (p = 0.04) and PD (p = 0.03) groups. INTERPRETATION: Automated speech analysis might provide a useful additional biomarker of parkinsonism for the assessment of disease progression and therapeutic interventions. ANN NEUROL 2021;90:62-75.

Linguistic Abnormalities in Isolated Rapid Eye Movement Sleep Behavior Disorder.

BACKGROUND: Patients with synucleinopathies frequently display language abnormalities. However, whether patients with isolated rapid eye movement sleep behavior disorder (iRBD) have prodromal language impairment remains unknown. OBJECTIVE: We examined whether the linguistic abnormalities in iRBD can serve as potential biomarkers for conversion to synucleinopathy, including the possible effect of mild cognitive impairment (MCI), speaking task, and automation of analysis procedure. METHODS: We enrolled 139 Czech native participants, including 40 iRBD without MCI and 14 iRBD with MCI, compared with 40 PD without MCI, 15 PD with MCI, and 30 healthy control subjects. Spontaneous discourse and story-tale narrative were transcribed and linguistically annotated. A quantitative analysis was performed computing three linguistic features. Human annotations were compared with fully automated annotations. RESULTS: Compared with control subjects, patients with iRBD showed poorer content density, reflecting the reduction of content words and modifiers. Both PD and iRBD subgroups with MCI manifested less occurrence of unique words and a higher number of n-grams repetitions, indicating poorer lexical richness. The spontaneous discourse task demonstrated language impairment in iRBD without MCI with an area under the curve of 0.72, while the story-tale narrative task better reflected the presence of MCI, discriminating both PD and iRBD subgroups with MCI from control subjects with an area under the curve of up to 0.81. A strong correlation between manually and automatically computed results was achieved. CONCLUSIONS: Linguistic features might provide a reliable automated method for detecting cognitive decline caused by prodromal neurodegeneration in subjects with iRBD, providing critical outcomes for future therapeutic trials. © 2022 International Parkinson and Movement Disorder Society.

Dysprosody in Isolated REM Sleep Behavior Disorder with Impaired Olfaction but Intact Nigrostriatal Pathway.

BACKGROUND: Impairments of olfactory and speech function are likely early prodromal symptoms of α-synucleinopathy. OBJECTIVE: The aim of this study is to assess whether dysprosody is present in isolated rapid eye movement sleep behavior disorder (iRBD) with hyposmia/anosmia and a normal nigrostriatal system. METHODS: Pitch variability during speech was investigated in 17 iRBD subjects with normal olfactory function (iRBD-NOF), 30 iRBD subjects with abnormal olfactory function (iRBD-AOF), and 50 healthy controls. iRBD subjects were evaluated using the University of Pennsylvania Smell Identification Test and [123I]-2ß-carbomethoxy-3ß-(4-iodophenyl)-N-(3-fluoropropyl)-nortropane dopamine transporter single-photon emission computed tomography (DAT-SPECT). All iRBD subjects completed the 24-month follow-up with DAT-SPECT, speech, and olfactory testing. RESULTS: At baseline, only iRBD-AOF showed monopitch when compared to iRBD-NOF (P = 0.04) and controls (P = 0.03), with no difference between iRBD-NOF and controls (P = 1). At follow-up, dysprosody progressed only in iRBD-AOF with abnormal DAT-SPECT (P = 0.03). CONCLUSION: Prosody is impaired in hyposmic but not in normosmic iRBD subjects before the nigrostriatal dopaminergic transmission is affected (Braak stage 2). © 2021 International Parkinson and Movement Disorder Society.

Increased Transferrin Sialylation Predicts Phenoconversion in Isolated REM Sleep Behavior Disorder.

BACKGROUND: Sialic acid-protein interactions are involved in regulating central nervous system immunity; therefore, derangements in sialylation could be involved in neurodegeneration. OBJECTIVES: We evaluate the differences in serum transferrin sialylation in prodromal and early-stage Parkinson's disease (PD), its relation to substantia nigra degeneration, and the risk of phenoconversion to manifest disease. METHODS: Sixty treatment-naive PD patients; 72 polysomnography-confirmed isolated rapid eye movement sleep behavior disorder (iRBD) patients, that is, patients with prodromal synucleinopathy; and 46 healthy volunteers aged ≥45 years and drinking ≤60 standard drinks per month were included. The proportion of serum low-sialylated, carbohydrate-deficient transferrin (CDT) isoforms was assessed using high-performance liquid chromatography, and the values were adjusted for alcohol intake (CDTadj ). Dopamine transporter single-photon emission computed tomography (DaT-SPECT) imaging was performed. In iRBD, phenoconversion risk of DaT-SPECT and CDTadj was evaluated using Cox regression adjusted for age and sex. RESULTS: Median CDTadj was lower in PD (1.1 [interquartile range: 1.0-1.3]%) compared to controls (1.2 [1.1-1.6]%) (P = 0.001). In iRBD, median CDTadj was lower in subjects with abnormal (1.1 [0.9-1.3]%) than normal (1.3 [1.2-1.6]%) DaT-SPECT (P = 0.005). After a median 44-month follow-up, 20% of iRBD patients progressed to a manifest disease. Although iRBD converters and nonconverters did not significantly differ in CDTadj levels (P = 0.189), low CDTadj increased the risk of phenoconversion with hazard ratio 3.2 (P = 0.045) but did not refine the phenoconversion risk associated with abnormal DaT-SPECT yielding hazard ratio 15.8 (P < 0.001). CONCLUSIONS: Decreased serum CDTadj is associated with substantia nigra degeneration in synucleinopathies. iRBD patients with low CDTadj are more likely to phenoconvert to manifest disease. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson Movement Disorder Society.

Automated speech analysis in early untreated Parkinson's disease: Relation to gender and dopaminergic transporter imaging.

BACKGROUND: The mechanisms underlying speech abnormalities in Parkinson's disease (PD) remain poorly understood, with most of the available evidence based on male patients. This study aimed to estimate the occurrence and characteristics of speech disorder in early, drug-naive PD patients with relation to gender and dopamine transporter imaging. METHODS: Speech samples from 60 male and 40 female de novo PD patients as well as 60 male and 40 female age-matched healthy controls were analyzed. Quantitative acoustic vocal assessment of 10 distinct speech dimensions related to phonation, articulation, prosody, and speech timing was performed. All patients were evaluated using [123]I-2b-carbomethoxy-3b-(4-iodophenyl)-N-(3-fluoropropyl) nortropane single-photon emission computed tomography and Montreal Cognitive Assessment. RESULTS: The prevalence of speech abnormalities in the de novo PD cohort was 56% for male and 65% for female patients, mainly manifested with monopitch, monoloudness, and articulatory decay. Automated speech analysis enabled discrimination between PD and controls with an area under the curve of 0.86 in men and 0.93 in women. No gender-specific speech dysfunction in de novo PD was found. Regardless of disease status, females generally showed better performance in voice quality, consonant articulation, and pauses production than males, who were better only in loudness variability. The extent of monopitch was correlated to nigro-putaminal dopaminergic loss in men (r = 0.39, p = 0.003) and the severity of imprecise consonants was related to cognitive deficits in women (r = -0.44, p = 0.005). CONCLUSIONS: Speech abnormalities represent a frequent and early marker of motor abnormalities in PD. Despite some gender differences, our findings demonstrate that speech difficulties are associated with nigro-putaminal dopaminergic deficits.

Guidelines for Speech Recording and Acoustic Analyses in Dysarthrias of Movement Disorders.

Most patients with movement disorders have speech impairments resulting from sensorimotor abnormalities that affect phonatory, articulatory, and prosodic speech subsystems. There is widespread cross-discipline use of speech recordings for diagnostic and research purposes, despite which there are no specific guidelines for a standardized method. This review aims to combine the specific clinical presentations of patients with movement disorders, existing acoustic assessment protocols, and technological advances in capturing speech to provide a basis for future research in this field and to improve the consistency of clinical assessments. We considered 3 areas: the recording environment (room, seating, background noise), the recording process (instrumentation, vocal tasks, elicitation of speech samples), and the acoustic outcome data. Four vocal tasks, namely, sustained vowel, sequential and alternating motion rates, reading passage, and monologues, are integral aspects of motor speech assessment. Fourteen acoustic vocal speech features, including their hypothesized pathomechanisms with regard to typical occurrences in hypokinetic or hyperkinetic dysarthria, are hereby recommended for quantitative exploratory analysis. Using these acoustic features and experimental speech data, we demonstrated that the hyperkinetic dysarthria group had more affected speech dimensions compared with the healthy controls than had the hypokinetic speakers. Several contrasting speech patterns between both dysarthrias were also found. This article is the first attempt to provide initial recommendations for a standardized way of recording the voice and speech of patients with hypokinetic or hyperkinetic dysarthria; thus allowing clinicians and researchers to reliably collect, acoustically analyze, and compare vocal data across different centers and patient cohorts. © 2020 International Parkinson and Movement Disorder Society.

Validation of cepstral peak prominence in assessing early voice changes of Parkinson's disease: Effect of speaking task and ambient noise.

Although the cepstral peak prominence (CPP) and its variant, the cepstral peak prominence smooth (CPPS), are considered to be robust acoustic measures for the evaluation of dysphonia, whether they are sensitive to capture early voice changes in Parkinson's disease (PD) has not yet been explored. This study aimed to investigate the voice changes via the CPP measures in the idiopathic rapid eye movement sleep behavior disorder (iRBD), a special case of prodromal neurodegeneration, and recently diagnosed and advanced-stage Parkinson's disease (AS-PD) patients using different speaking tasks across noise-free and noisy environments. The sustained vowel phonation, reading of passages, and monologues of 60 early stage untreated PD, 30 advanced-stage Parkinson's disease, 60 iRBD, and 60 healthy control (HC) participants were evaluated. Significant differences were found between the PD groups and controls in sustained phonation via the CPP (p < 0.05) and CPPS (p < 0.01) and the monologue via the CPP (p < 0.01), although neither the CPP nor CPPS measures were sufficiently sensitive to capture the possible prodromal dysphonia in the iRBD. The quality of the CPP and CPPS measures was influenced substantially by the addition of ambient noise. It was anticipated that the CPP measures might serve as a promising digital biomarker in assessing the dysphonia from the early stages of PD.

Effect of reading passage length on quantitative acoustic speech assessment in Czech-speaking individuals with Parkinson's disease treated with subthalamic nucleus deep brain stimulation.

Little is known about the minimum sample length required for the stable acoustic assessment of speech in Parkinson's disease (PD). This study aimed to investigate the effect of the duration of the reading passage on the determination of reliable acoustic patterns in individuals with PD treated with subthalamic nucleus deep brain stimulation. A phonetically balanced reading text of 313 words was collected from 32 Czech persons with PD, and 32 age- and sex-matched healthy controls. The reading passage was segmented to produce ten sub-texts of increasing length ranging from a one- to a ten-segment-long sub-text. An error rate analysis was used to estimate the required stabilization value by evaluating the differences between the sub-texts and the entire text across seven hypokinetic dysarthria features. The minimum length of a reading passage equal to 128 words was found to be necessary for acoustic assessment, with similar lengths being required for the controls (120 words) and the two PD subgroups, including Parkinsonian individuals with a mild (126 words) and moderate (128 words) dysarthria severity. The current study provides important guidelines for the necessary sample length for future expert instrumental dysarthria assessments and assists in decreasing the time required for clinical speech evaluations.

Efficient and Versatile Model for Vibrational STEM-EELS.

We introduce a novel method for the simulation of the impact scattering in vibrational scanning transmission electron microscopy electron energy loss spectroscopy simulations. The phonon-loss process is modeled by a combination of molecular dynamics and elastic multislice calculations within a modified frozen phonon approximation. The key idea is thereby to use a so-called δ thermostat in the classical molecular dynamics simulation to generate frequency dependent configurations of the vibrating specimen's atomic structure. The method includes correlated motion of atoms and provides vibrational spectrum images at a cost comparable to standard frozen phonon calculations. We demonstrate good agreement of our method with simulations and experiments for a 15 nm flake of hexagonal boron nitride.

Dysarthria enhancement mechanism under external clear speech instruction in Parkinson's disease, progressive supranuclear palsy and multiple system atrophy.

Clear speech refers to intentionally modifying conversational speech to maximise intelligibility. This study aimed to compare the speech behaviour of patients with progressive supranuclear palsy (PSP), multiple system atrophy (MSA) and Parkinson's disease (PD) under conversational and clear speech conditions to gain greater pathophysiological insight. A total of 68 participants including 17 PD, 17 MSA, 17 PSP and 17 healthy controls (HC) performed two readings of the same standardized passage. During the first reading, participants were instructed to read the text in an ordinary way, while during the second reading to read the text as clearly as possible. Acoustic analyses were based upon measurements of mean loudness, loudness variability, pitch variability, vowel articulation, articulation rate and speech severity. During clear speech production, PD patients were able to achieve improvements mainly in loudness (p < 0.05) and pitch variability (p < 0.001), leading to a reduction in overall speech severity (p < 0.001), whereas PSP and MSA patients were able to modulate only articulation rate (p < 0.05). Contrary to HC and PD groups, which slowed or maintained articulation rate, PSP and MSA groups employed a markedly faster articulation rate under the clear speech condition indicating an opposing approach to speech adaptation. Patients with atypical Parkinsonism showed a different strategy to intentionally improve their speech performance following a simple request to produce speech more clearly compared to PD, suggesting important therapeutic implications for speech rehabilitation management.

Speech disorder and vocal tremor in postural instability/gait difficulty and tremor dominant subtypes of Parkinson's disease.

Hypokinetic dysarthria is a multidimensional impairment affecting all main speech subsystems with variable patterns and severity across individual Parkinson's disease (PD) patients. We can thus assume that inter-individual abnormal speech patterns are related to the various clinical subtypes of PD with different prominent motor symptoms. The aim of this cross-sectional study was to compare speech disorder between patients with the postural instability/gait difficulty (PIGD) and tremor-dominant (TD) motor phenotypes of PD. Speech samples were acquired from a total of 63 participants, including 21 PIGD patients, 21 TD patients, and 21 healthy controls. Quantitative acoustic vocal assessment of 12 unique speech dimensions related to phonation, vocal tremor, oral diadochokinesis, articulation, prosody and speech timing was performed. Speech impairment was more pronounced in the PIGD group than in the TD group, with an area under the curve of 0.76. Patients in the PIGD group manifested abnormalities in pitch breaks, articulatory decay, decreased rate of follow-up speech segments and inappropriate silences, apart from monopitch and irregular AMR that were affected in TD group as well. An abnormal vocal tremor was present in only 10% of PD patients, with no differences between the PD phenotypes. We found a correlation between non-motor symptom severity and speech timing (r = - 0.40, p = 0.009). The present study demonstrates that speech disorder reflects the underlying motor phenotypes. Vocal tremor appeared to be an isolated phenomenon that does not share similar pathophysiology with limb tremor.

Eye movement abnormalities are associated with brainstem atrophy in Wilson disease.

BACKGROUNDS: This study aims to characterize eye movement abnormalities in Wilson disease and examine their association with the degree of brainstem atrophy. METHODS: Twenty patients (10 males, mean age 46.8, SD 8.9 years) with genetically confirmed neurological WD on stable anti-copper treatment and 20 age- and sex-matched healthy subjects were examined. Eye movements, including prosaccade and antisaccade tasks, were evaluated using infrared videooculography. MRI was performed using 1.5 T system, and T2-weighted images were used for the measurement of midbrain and pontine area on mid-sagittal slices. Clinical severity was assessed using the Unified Wilson's Disease Rating Scale (UWDRS). RESULTS: Compared to healthy controls, WD patients showed prolonged latencies of horizontal prosaccades and hypometry of both horizontal (p = 0.04) and vertical (p = 0.0046) prosaccades. In the antisaccade task, WD patients showed prolonged latency of both horizontal (p = 0.04) and vertical antisaccades (p = 0.047) and increased error rate of vertical antisaccades (p = 0.04). There is a significant association between midbrain area and horizontal latencies (r = -0.53; p = 0.02) and vertical maximum speed in prosaccades (r = 0.47; p = 0.04). The pons area inversely correlated with horizontal prosaccade and antisaccade latencies (p = 0.007). CONCLUSIONS: We showed impairments of ocular saccades such as prolonged latencies, hypometry, and increased error rate in antisaccades. The strong association between prolonged latencies of prosaccades and the brainstem atrophy suggests that VOG might serve as a sensitive electrophysiological marker of brainstem dysfunction in WD.

Atomic scale imaging of magnetic circular dichroism by achromatic electron microscopy.

In order to obtain a fundamental understanding of the interplay between charge, spin, orbital and lattice degrees of freedom in magnetic materials and to predict and control their physical properties1-3, experimental techniques are required that are capable of accessing local magnetic information with atomic-scale spatial resolution. Here, we show that a combination of electron energy-loss magnetic chiral dichroism 4 and chromatic-aberration-corrected transmission electron microscopy, which reduces the focal spread of inelastically scattered electrons by orders of magnitude when compared with the use of spherical aberration correction alone, can achieve atomic-scale imaging of magnetic circular dichroism and provide element-selective orbital and spin magnetic moments atomic plane by atomic plane. This unique capability, which we demonstrate for Sr2FeMoO6, opens the door to local atomic-level studies of spin configurations in a multitude of materials that exhibit different types of magnetic coupling, thereby contributing to a detailed understanding of the physical origins of magnetic properties of materials at the highest spatial resolution.

Publisher Correction: Atomic scale imaging of magnetic circular dichroism by achromatic electron microscopy.

In Fig. 1 of the version of this Letter originally published, the word 'Subtract' was missing from the green box to the left of panel f. This has now been corrected in all versions of the Letter.

Proposal for Measuring Magnetism with Patterned Apertures in a Transmission Electron Microscope.

We propose a magnetic measurement method utilizing a patterned postsample aperture in a transmission electron microscope. While utilizing electron magnetic circular dichroism, the method circumvents previous needs to shape the electron probe to an electron vortex beam or astigmatic beam. The method can be implemented in standard scanning transmission electron microscopes by replacing the spectrometer entrance aperture with a specially shaped aperture, hereafter called a ventilator aperture. The proposed setup is expected to work across the whole range of beam sizes-from wide parallel beams down to atomic resolution magnetic spectrum imaging.

Why patients with multiple sclerosis perceive improvement of gait during treatment with natalizumab?

Gait impairment is one of the common manifestations of multiple sclerosis (MS) and contributes to a loss of quality of life. Natalizumab, an anti-α4 integrin monoclonal antibody, has been shown to have an effect in treatment of MS, reducing relapses and inflammatory lesions. Aim of our study was to assess how patients perceive gait impairment over the first year of treatment with natalizumab and what is the objective correlate of this change. This is an open-label prospective observational study. Subjective gait evaluation was measured by Multiple Sclerosis Walking Scale-12 (MSWS-12). Objective gait assessment included Timed 25-Foot Walk Test (T25FW) and spatiotemporal parameters of gait measured by a GAITRite instrument during a self-selected speed of walking (normal walk) and a fast speed of walking (fast walk). We analysed data of 50 patients with a relapsing-remitting form of MS, median EDSS 3.5 (range 1.5-5). MSWS-12 score significantly decreased between the baseline and month 12 of treatment (p < 0.001). Walking velocity and step length were significantly improved in Normal walk tests (p < 0.001). During the Fast walk tests, a step length and a double support time of the gait cycle were significantly improved (p = 0.001). Change in MSWS-12 score confirmed the clinically significant improvement of gait in patients with MS treated with natalizumab for 1 year. The analysis of spatiotemporal gait parameters has shown a significant improvement in self-selected gait velocity and step length.

Eye movements in idiopathic rapid eye movement sleep behaviour disorder: High antisaccade error rate reflects prefrontal cortex dysfunction.

Abnormalities of eye movements have been reported in patients with Parkinson's disease (PD). However, it is unclear if they occur in the prodromal stage of synucleinopathy represented by idiopathic rapid eye movement sleep behaviour disorder (iRBD). We thus aimed to study eye movements in subjects with iRBD and in de novo PD, to assess if their abnormalities may serve as a clinical biomarker of neurodegeneration. Fifty subjects with polysomnography-confirmed iRBD (46 male, age 40-79 years), 18 newly diagnosed, untreated PD patients (13 male, age 43-75 years) and 25 healthy controls (20 male, age 42-79 years) were prospectively enrolled. Horizontal and vertical ocular prosaccades and antisaccades were investigated with video-oculography. All patients completed the MDS-UPDRS and the Montreal Cognitive Assessment. In addition, a neuropsychological battery was performed on iRBD subjects. When compared with healthy controls, both de novo PD patients and iRBD subjects showed increased error rates in the horizontal antisaccade task (p < 0.01, p < 0.05 respectively). In the iRBD group, the error rates in horizontal and vertical antisaccades correlated with performances in the Prague Stroop Test and the Grooved Pegboard Test, as well as with motor scores of the MDS-UPDRS. De novo PD patients showed a lower gain (p < 0.01) compared with controls. In conclusion, the increased error rate in the antisaccade task of iRBD and PD patients reflects a dysfunction of the dorsolateral prefrontal cortex and is related to the impairment of executive functions and attention.