Functional neurological disorder: a comparative analysis of experience of Czech, Slovak, and Italian neurologists.

AIM OF STUDY: We aimed to compare knowledge, opinions, and clinical experiences among Czech, Slovak, and Italian neurologists to identify potential educational gaps and unify understanding. CLINICAL RATIONALE FOR STUDY: Functional neurological disorder (FND) is a disabling condition characterised by motor, sensory, or cognitive symptoms which are incompatible with other neurological disorders. Novel diagnostic and treatment approaches have improved FND management. However, the extent of their adoption, and any differences or similarities across European communities, remain to be established. MATERIAL AND METHODS: Members of the Czech and Slovak Neurological Societies were invited via e-mail to participate in a 14- -item web-based survey investigating their approach to FND. This data was compared to results from a previous study involving 492 Italian neurologists. RESULTS: 232 questionnaires were completed by Czech and Slovak neurologists (CZ-SK). Similarities were found between CZ- -SK and Italian neurologists in their preference for the term 'FND' over other psychological-related terms and in explaining symptoms as due to abnormal functioning of the nervous system rather than attributing them to mental illness. However, only fewer than 5% in both groups thought that simulation was highly unlikely. Both groups reported relying on positive signs (e.g. inconsistency, distractibility) according to the current diagnostic criteria, but also a tendency to perform additional tests to exclude other causes. However, some differences were observed: Italian neurologists placed a greater emphasis on psychological factors including litigation. CZ-SK neurologists were more likely to suggest physiotherapy as a treatment option and to provide educational intervention for patients and their relatives. CONCLUSIONS: Overall, our findings suggest that although Czech, Slovak, and Italian neurologists have adopted some new developments in the field of FND, significant gaps still exist in their understanding and common practices regarding conceptualisation, diagnosis, and treatment. CLINICAL IMPLICATIONS: Our results suggest that promoting knowledge through postgraduate curricula and teaching courses for neurologists is necessary to optimise patient management in various European countries.

Trait-related neural basis of attentional bias to emotions: a tDCS study.

Negative emotional stimuli can strongly bias attention, particularly in individuals with high levels of dispositional negative affect (NA). The current study investigated whether the prefrontal cortex (PFC), a brain region involved in the top-down regulation of emotional processing, plays a different role in controlling attention to emotions, depending on the individual NA. Sham and anodal transcranial direct current stimulation (tDCS) was delivered over the right or left PFC while assessing attentional bias (AB) to emotions (happy, angry, sad faces) in individuals with higher and lower trait NA. When tDCS was inactive (sham), individuals with higher trait NA showed AB toward angry and away from sad faces, while individuals with lower trait NA presented with no AB. Right anodal-tDCS abolished the AB toward angry faces and induced an AB toward sad faces in individuals with higher trait NA, while no effect was found in individuals with lower trait NA. Left anodal-tDCS abolished any AB in individuals with higher trait NA and induced an AB away from happy faces in individuals with lower trait NA. These findings confirm a critical role of trait NA in AB to emotions and demonstrate a different involvement of PFC in emotional processing based on dispositional affect.

Performance validity tests in nonlitigant patients with functional motor disorder.

BACKGROUND AND PURPOSE: Performance validity tests (PVTs) are used in neuropsychological assessments to detect patterns of performance suggesting that the broader evaluation may be an invalid reflection of an individual's abilities. Data on functional motor disorder (FMD) are currently poor and conflicting. We aimed to examine the rate of failure on three different PVTs of nonlitigant, non-compensation-seeking FMD patients, and we compared their performance to that of healthy controls and controls asked to simulate malingering (healthy simulators). METHODS: We enrolled 29 nonlitigant, non-compensation-seeking patients with a clinical diagnosis of FMD, 29 healthy controls, and 29 healthy simulators. Three PVTs, the Coin in the Hand Test (CIH), the Rey 15-Item Test (REY), and the Finger Tapping Test (FTT), were employed. RESULTS: Functional motor disorder patients showed low rates of failure on the CIH and REY (7% and 10%, respectively) and slightly higher rates on the FTT (15%, n = 26), which implies a motor task. Their performance was statistically comparable to that of healthy controls but statistically different from that of healthy simulators (p < 0.001). Ninety-three percent of FMD patients, 7% of healthy simulators, and 100% of healthy controls passed at least two of the three tests. CONCLUSIONS: Performance validity test performance of nonlitigant, non-compensation-seeking patients with FMD ranged from 7% to 15%. Patients' performance was comparable to that of controls and significantly differed from that of simulators. This simple battery of three PVTs could be of practical utility and routinely used in clinical practice.

Placebo effect on gait: a way to reduce the dual-task cost in older adults.

The ability to perform two tasks simultaneously is essential for daily activities. In older adults, this ability is markedly reduced, as evidenced by the dual-task cost on gait. Preliminary evidences indicate that the dual-task cost can be influenced by different types of manipulations. Here, we explored the effectiveness of a new approach to reduce the dual-task cost, based on the placebo effect, a psychobiological phenomenon whereby a positive outcome follows the administration of an inert device thought to be effective. Thirty-five healthy older adults were asked to walk on a sensorized carpet (single-task condition) and to walk while counting backward (dual-task condition) in two sessions (pre-test and post-test). A placebo group, randomly selected, underwent sham transcranial direct current stimulation over the supraorbital areas between sessions, along with information about its positive effects on concentration and attention. A control group did not receive any intervention between sessions. The dual-task cost was significantly reduced in the placebo group at the post-test session compared to the pre-test for several gait parameters (Cohen's d > 1.43). At the post-test session, the dual-task cost was also lower in the placebo group than in the control group (d > 0.73). Cognitive (number of subtractions and number of errors) and subjective (perceived mental fatigability) variables remained stable across sessions. The reduced dual-task cost in the placebo group could indicate the ability to re-establish the allocation of attentional resources between tasks. These findings could contribute to the development of cognitive strategies that leverage positive expectations to boost motor control in older adults.

Attentional bias to emotions after prolonged endurance exercise is modulated by age.

Physical exercise has an impact in biasing attention to positive or negative emotional stimuli. While attentional shift to emotions varies with age, evidence is lacking on the effect of prolonged endurance exercise on age-related attentional bias to emotions. This study aims at filling this knowledge gap, by applying a dot-probe task to measure attentional bias to emotions before and after a half-marathon in healthy participants of different ages (age range 21-65 years). State anxiety, positive and negative affect were also assessed. Younger adults showed attentional bias towards anger and away from sadness after the race, supporting the hypothesis of the congruency between the high-arousing task and the associated emotion (anger) in the modulation of attention. Conversely, older adults showed a bias away from anger, likely representing an attempt to maintain an optimal emotional level after the competition. This study sheds new light on how age impacts on emotional mechanisms involved in prolonged endurance exercise and suggests that regulatory processes in response to stress may be involved differently, depending on age.

The effect of motor and cognitive placebos on the serial reaction time task.

Motor learning is a key component of human motor functions. Repeated practice is essential to gain proficiency over time but may induce fatigue. The aim of this study was to determine whether motor performance and motor learning (as assessed with the serial reaction time task, SRTT) and perceived fatigability (as assessed with subjective scales) are improved after two types of placebo interventions (motor and cognitive). A total of 90 healthy volunteers performed the SRTT with the right hand in three sessions (baseline, training and final). Before the training and the final session, one group underwent a motor-related placebo intervention in which inert electrical stimulation (TENS) was applied over the hand and accompanied by verbal suggestion that it improves movement execution (placebo-TENS). The other group underwent a cognitive-related placebo intervention in which sham transcranial direct current stimulation (tDCS) was delivered to the supraorbital area and accompanied by verbal suggestion that it increases attention (placebo-tDCS). A control group performed the same task without receiving treatment. Overall better performance on the SRTT (not ascribed to sequence-specific learning) was noted for the placebo-TENS group, which also reported less perceived fatigability at the physical level. The same was observed in a subgroup tested 24 hr later. The placebo-tDCS group reported less perceived fatigability, both at the mental and physical level. These findings indicate that motor- and cognitive-related placebo effects differently shape motor performance and perceived fatigability on a repeated motor task.

Cathodal Cerebellar tDCS Combined with Visual Feedback Improves Balance Control.

Balance control is essential to maintain a stable body position and to prevent falls. The aim of this study was to determine whether balance control could be improved by using cerebellar transcranial direct current stimulation (tDCS) and visual feedback in a combined approach. A total of 90 healthy volunteers were randomly assigned to six groups defined by the delivery of tDCS (cathodal or anodal or sham) and the provision or not of visual feedback on balance during the acquisition phase. tDCS was delivered over the cerebellar hemisphere ipsilateral to the dominant leg for 20 min at 2 mA during a unipedal stance task. Body sway (i.e., ankle angle and hip position) was measured as an overall maximal unit in anteroposterior and mediolateral direction, together with participant rating of perception of stability, before (baseline), during (acquisition), and after (final) the intervention. We found a reduction in body sway during the acquisition session when visual feedback alone was provided. When the visual feedback was removed (final session), however, body sway increased above baseline. Differently, the reduction in overall maximal body sway was maintained during the final session when the delivery of cathodal tDCS and visual feedback was combined. These findings suggest that cathodal tDCS may support the short-term maintenance of the positive effects of visual feedback on balance and provide the basis for a new approach to optimize balance control, with potential translational implications for the elderly and patients with impaired posture control.

Hedonicity in functional motor disorders: a chemosensory study assessing taste.

The aim of this study was to explore hedonicity to basic tastes in patients with functional motor disorders (FMDs) that are often associated with impairment in emotional processing. We recruited 20 FMD patients and 24 healthy subjects, matched for age and sex. Subjects were asked to rate the hedonic sensation (i.e., pleasant, neutral, and unpleasant) on a - 10 to +10 scale to the four basic tastes (sweet, sour, salty, and bitter) at different concentrations, and neutral stimuli (i.e., no taste stimulation) by means of the Taste Strips Test. Anxiety, depression, and alexithymia were assessed. FMD patients rated the highest concentration of sweet taste (6.7 ± 2.6) as significantly more pleasant than controls (4.7 ± 2.5, p = 0.03), and the neutral stimuli significantly more unpleasant (patients: - 0.7 ± 0.4, controls: 0.1 ± 0.4, p = 0.013). Hedonic ratings were not correlated to anxiety, depression, or alexithymia scores. Hedonic response to taste is altered in FMD patients. This preliminary finding might result from abnormal interaction between sensory processing and emotional valence.

When words hurt: Verbal suggestion prevails over conditioning in inducing the motor nocebo effect.

Perception and behavior are strongly influenced by the verbal information conveyed by other individuals (e.g., verbal suggestion) and by learning (e.g., conditioning). This influence is well represented by the placebo and nocebo effects, in which positive verbal suggestion associated with positive conditioning induces beneficial outcomes (placebo effect), while the opposite is true for the negative counterpart (nocebo effect). It is still unclear whether verbal suggestion and conditioning exert distinctive roles in influencing perception, behavior and motor system activity when they occur in opposite directions. To this purpose, fifty-three healthy volunteers were assigned to four groups characterized by either congruent or incongruent verbal suggestion and conditioning. Participants were asked to perform a force motor task by pressing a piston as strongly as possible. Transcranial magnetic stimulation over the primary motor cortex was used to record motor evoked potentials (MEP) and cortical silent period (CSP) from the muscle involved in the task. We found that negative verbal suggestion counteracted positive conditioning and induced sense of weakness, effort, and force decrements. MEP amplitude was stable, whereas the CSP duration shortened in all the groups throughout the procedure, indicating the involvement of cortical inhibitory circuits, independently of the type of verbal suggestion or conditioning. Our findings highlight a prevalent role of verbal suggestion over conditioning in determining a worsening (nocebo effect) but not an improvement (placebo effect) of motor performance. These results suggest that words associated with treatments should be chosen carefully to avoid negative outcomes, especially in sports and clinical settings.

The role of the dorsolateral prefrontal cortex in the motor placebo effect.

The neural correlates of the placebo effect in the motor domain are still unknown. The aim of this study was to tackle the role of a frontal cortical region, the dorsolateral prefrontal cortex (dlPFC). To this end, we stimulated the cortical site corresponding to the left dlPFC with transcranial direct current stimulation (tDCS) during a placebo procedure and measured any change in the motor placebo effect in all the participants and more specifically in placebo-responders. Three different experiments were conducted in which healthy volunteers performed a force motor task with the index finger. The placebo treatment consisted of transcutaneous electrical nerve stimulation (TENS). In Experiment 1 (expectation alone), participants were only verbally suggested about the positive effects of TENS. In Experiment 2 (expectation and conditioning), participants were verbally suggested about TENS and conditioned with a surreptitious increase in a visual feedback of force. In Experiment 3 (control procedure), participants were told that TENS was inefficient. Each participant was tested in three different days with anodal, cathodal and sham tDCS over the dlPFC. Results showed that in Experiment 1 and 2 force increased after the procedure, independently of tDCS. By focusing on placebo-responders, we found that in Experiment 1 force remained stable after active tDCS, whereas it increased after inactive tDCS. These findings bring new evidence on the neural underpinnings of the motor placebo effect, by showing that independently of the polarity, active tDCS over the left dlPFC may undermine the expectation-induced enhancement of force in placebo-responders.

The somatosensory temporal discrimination threshold changes after a placebo procedure.

In a recent study, we showed that tactile perception can be enhanced by applying a placebo manipulation consisting of verbal suggestion and conditioning (Fiorio et al., Neuroscience 217:96-104, 2012). Whether this change in perception is related to a better tactile functioning is still unknown. Aim of this study is to investigate whether placebo-induced enhancement of tactile perception results in better somatosensory temporal discrimination threshold (STDT), as a proxy of tactile acuity. To this purpose, a group of subjects (experimental group) was verbally influenced and conditioned about the effect of an inert cream in enhancing tactile perception, while a control group was informed about the real nature of the cream. In both groups, we measured STDT before and after cream application, by means of pairs of electrical stimuli delivered on the index fingertip and separated by ascending inter-stimulus intervals. STDT was defined as the shortest time interval at which the two stimuli were perceived as separated. Results revealed an increase in subjective perception of stimulus intensity and a reduction of STDT only in the experimental group. This study proves that a placebo procedure, consisting of verbal suggestion and a short conditioning, can reduce the temporal discrimination threshold.

Functional Connectivity Networks in Asymptomatic and Symptomatic DYT1 Carriers.

BACKGROUND: DYT1 mutation is characterized by focal to generalized dystonia and incomplete penetrance. To explore the complex perturbations in the different neural networks and the mutual interactions among them, we studied symptomatic and asymptomatic DTY1 mutation carriers by resting-state functional MRI. METHODS: A total of 7 symptomatic DYT1, 10 asymptomatic DYT1, and 26 healthy controls were considered. Resting-state functional MRI (Oxford Centre for Functional MRI of the Brain) [FMRIB] Software Library) (FSL) MELODIC, dual regression, (as a toolbox of FSL, with Nets is referred to "networks") (FSLNets) (http://fsl.fmrib.ox.ac.uk/fsl/fslwiki/FSLNets) was performed on 9 resting-state neural networks. RESULTS: DYT1 mutation signature (symptomatic DYT1 and asymptomatic DYT1) was characterized by increased connectivity in the dorsal attention network and in the left fronto-parietal network. Functional correlates of symptomatic DYT1 patients (symptomatic DYT1 vs healthy controls) showed increased connectivity in the sensorimotor network. DISCUSSION: This study argues that DYT1 dystonia is a network disorder, with crucial nodes in sensory-motor integration of posterior parietal structures. A better characterization of cortical networks involved in dystonia is crucial for possible neurophysiological therapeutic interventions. © 2016 International Parkinson and Movement Disorder Society.

Placebo-induced changes in excitatory and inhibitory corticospinal circuits during motor performance.

Despite behavioral evidence showing placebo modulations of motor performance, the neurophysiological underpinnings of these effects are still unknown. By applying transcranial magnetic stimulation (TMS) over the primary motor cortex, we investigated whether a placebo modulation of force could change the excitability of the corticospinal system. Healthy human volunteers performed a motor task by pressing a piston as strongly as possible with the right index finger. Two experimental groups were instructed that treatment with peripheral low-frequency transcutaneous electrical nerve stimulation (TENS) applied on the first dorsal interosseus would induce force enhancement. One experimental group was conditioned about the effects of TENS with a surreptitious amplification of the visual feedback signaling the force level. The other group, instead, was only verbally influenced, without conditioning. At the end of the instructive placebo procedure, the two experimental groups reached higher levels of force, believed that TENS had been effective and expected to perform better compared with two control groups, who were not influenced about TENS. Moreover, the experimental groups presented enhanced excitability of the corticospinal system in the muscle specifically involved in the task (first dorsal interosseus), as shown by increased amplitude of the motor evoked potentials and decreased duration of the cortical silent period (the latter only in the conditioned group). Crucially, the TMS pulse was delivered when all the subjects exerted the same amount of force, ruling out bottom-up influences. These findings hint at a top-down, cognitive enhancement of corticospinal excitability as a neural signature of placebo modulation of motor performance.

Disentangling the Role of Cortico-Basal Ganglia Loops in Top-Down and Bottom-Up Visual Attention: An Investigation of Attention Deficits in Parkinson Disease.

It is solidly established that top-down (goal-driven) and bottom-up (stimulus-driven) attention mechanisms depend on distributed cortical networks, including prefrontal and frontoparietal regions. On the other hand, it is less clear whether the BG also contribute to one or the other of these mechanisms, or to both. The current study was principally undertaken to clarify this issue. Parkinson disease (PD), a neurodegenerative disorder primarily affecting the BG, has proven to be an effective model for investigating the contribution of the BG to different brain functions; therefore, we set out to investigate deficits of top-down and bottom-up attention in a selected cohort of PD patients. With this objective in mind, we compared the performance on three computerized tasks of two groups of 12 parkinsonian patients (assessed without any treatment), one otherwise pharmacologically treated and the other also surgically treated, with that of a group of controls. The main behavioral tool for our study was an attentional capture task, which enabled us to tap the competition between top-down and bottom-up mechanisms of visual attention. This task was suitably combined with a choice RT and a simple RT task to isolate any specific deficit of attention from deficits in motor response selection and initiation. In the two groups of patients, we found an equivalent increase of attentional capture but also comparable delays in target selection in the absence of any salient distractor (reflecting impaired top-down mechanisms) and movement initiation compared with controls. In contrast, motor response selection processes appeared to be prolonged only in the operated patients. Our results confirm that the BG are involved in both motor and cognitive domains. Specifically, damage to the BG, as it occurs in PD, leads to a distinct deficit of top-down control of visual attention, and this can account, albeit indirectly, for the enhancement of attentional capture, reflecting weakened ability of top-down mechanisms to antagonize bottom-up control.

The role of the cerebellum in dynamic changes of the sense of body ownership: a study in patients with cerebellar degeneration.

The sense of the body is deeply rooted in humans, and it can be experimentally manipulated by inducing illusions in at least two aspects: a subjective feeling of ownership and a proprioceptive sense of limb position. Previous studies mapped these different aspects onto anatomically distinct neuronal regions, with the ventral premotor cortex processing subjective experience of ownership and the inferior parietal lobule processing proprioceptive calibration. Lines of evidence suggest an involvement also of the cerebellum, but its precise role is not clear yet. To investigate the contribution of the cerebellum in the sense of body ownership, we applied the rubber-hand illusion paradigm in 28 patients affected by neurodegenerative cerebellar ataxia, selectively involving the cerebellum, and in 26 age-matched control participants. The rubber hand illusion is established by synchronous stroking of the participants' real unseen hand and a visible fake hand. Short asynchronous stroking does not bring about the illusion. We tested the subjective experience of the illusion, evaluated through a questionnaire and the proprioceptive drift of the real unseen hand toward the viewed rubber hand. In patients with cerebellar ataxia, we observed reduced sense of the subjective illusory experience specifically after synchronous stroking. In contrast, the proprioceptive drift was enhanced after synchronous and after asynchronous stimulation. These findings support the contention that the mechanisms underlying the presence of the illusion and the proprioceptive drift may be differently affected in different conditions. Impairment of the subjective sense of the illusion in cerebellar patients might hint at an involvement of cerebellar-premotor networks, whereas the proprioceptive drift typically associated with synchronous stroking appears to rely on other circuits, likely involving the cerebellum and the parietal regions.

Aristotle's illusion reveals interdigit functional somatosensory alterations in focal hand dystonia.

In focal hand dystonia, the cortical somatosensory representation of the fingers is abnormal, with overlapping receptive fields and reduced interdigit separation. These abnormalities are associated with deficits in sensory perception, as previously demonstrated by applying tactile stimuli to one finger at a time. What is still unknown is whether the sensory deficits can be observed when tactile perception involves more than one finger. To address this issue, we applied 'Aristotle's illusion' to 15 patients with focal hand dystonia, 15 patients with dystonia not affecting the hand (blepharospasm and cervical dystonia) and 15 healthy control subjects. In this illusion, one object touching the contact point of two crossed fingertips is perceived as two objects by a blindfolded subject. The same object placed between two parallel fingertips is correctly perceived as one. The illusory doubling sensation is because of the fact that the contact point between the crossed fingers consists of non-adjacent and functionally unrelated skin regions, which usually send sensory signals to separate spots in the somatosensory cortex. In our study, participants were touched by one sphere between the second-third digits, the second-fourth digits and the fourth-fifth digits of both hands, either in crossed or in parallel position, and had to refer whether they felt one or two stimuli. The percentage of 'two stimuli' responses was an index of the illusory doubling. Both healthy control subjects and dystonic patients presented Aristotle's illusion when the fingers were crossed. However, patients with focal hand dystonia presented a significant reduction of the illusion when the sphere was placed between the crossed fourth and fifth digits of the affected hand. This reduction correlated with the severity of motor disease at the fingers. Similar findings were not observed in non-hand dystonia and control groups. The reduction of Aristotle's illusion in non-affected fingers and its preservation in affected fingers suggests dissociation between the abnormal processing of sensory signals and the motor impairment. Based on previous evidence showing that the sensory signals coming from the fourth digit determine lower activation in the somatosensory cortex than those coming from the fifth digit, we suggest that in the crossed position, the tactile information conveyed by the fifth digit prevailed over the fourth digit, thus resulting in the perception of one stimulus. The reduction of the illusory doubling perception, therefore, may represent the functional correlate of the different level of activation between the fourth and the fifth digit in the somatosensory cortex.

Preserving the placebo effect after disclosure: A new perspective on non-deceptive placebos.

The present study explores whether a particular style of placebo disclosure could serve as a tool to foster a renewed trust in one's own inherent resources and elicit a meaningful placebo effect. In a motor performance task, two placebo groups received inert transcutaneous electrical nerve stimulation (TENS) in each of four sessions along with information on its force-enhancing properties. Before the final session, one of the placebo groups was informed about the placebo, which was portrayed as a means to unleash an inherent potential. Along with force, we systematically monitored task-specific self-efficacy to test whether this variable would be differentially modulated in the two placebo groups. Compared to two control groups, placebo groups showed higher force and self-efficacy in the last session. No differences in self-efficacy were observed in the placebo groups even after revealing the placebo procedure, suggesting that the disclosure was effective in 'safeguarding' individuals' self-efficacy. These findings may have important implications, paving the way for the use of placebos that not only are ethically permissible but also support individuals' self-efficacy.

How Does Postural Control in Patients with Functional Motor Disorders Adapt to Multitasking-Based Immersive Virtual Reality?

BACKGROUND: Motor symptoms in functional motor disorders (FMDs) refer to involuntary, but learned, altered movement patterns associated with aberrant self-focus, sense of agency, and belief/expectations. These conditions commonly lead to impaired posture control, raising the likelihood of falls and disability. Utilizing visual and cognitive tasks to manipulate attentional focus, virtual reality (VR) integrated with posturography is a promising tool for exploring postural control disorders. OBJECTIVES: To investigate whether postural control can be adapted by manipulating attentional focus in a 3D immersive VR environment. METHODS: We compared postural parameters in 17 FMDs patients and 19 age-matched healthy controls over a single session under four increasingly more complex and attention-demanding conditions: simple fixation task (1) in the real room and (2) in 3D VR room-like condition; complex fixation task in a 3D VR city-like condition (3) avoiding distractors and (4) counting them. Dual-task effect (DTE) measured the relative change in performance induced by the different attention-demanding conditions on postural parameters. RESULTS: Patients reduced sway area and mediolateral center of pressure displacement velocity DTE compared to controls (all, P < 0.049), but only under condition 4. They also showed a significant reduction in the sway area DTE under condition 4 compared to condition 3 (P = 0.025). CONCLUSIONS: This study provides novel preliminary evidence for the value of a 3D immersive VR environment combined with different attention-demanding conditions in adapting postural control in patients with FMDs. As supported by quantitative and objective posturographic measures, our findings may inform interventions to explore FMDs pathophysiology.

Sensory tricks in primary cervical dystonia depend on visuotactile temporal discrimination.

A characteristic feature of primary cervical dystonia is the presence of "sensory tricks" as well as the impairment of temporal and spatial sensory discrimination on formal testing. The aim of the present study was to test whether the amount of improvement of abnormal head deviation due to a sensory trick is associated with different performance of temporal sensory discrimination in patients with cervical dystonia. We recruited 32 patients with cervical dystonia. Dystonia severity was assessed using the Toronto Western Spasmodic Torticollis Rating Scale. Patients were rated according to clinical improvement to a sensory trick and assigned to 1 of the following groups: (1) no improvement (n = 6), (2) partial improvement (n = 17), (3) complete improvement (n = 9). Temporal discrimination thresholds were assessed for visual, tactile, and visuotactile modalities. Disease duration was shorter (P = .026) and dystonia severity lower (P = .033) in the group with complete improvement to sensory tricks compared with the group with partial improvement to sensory tricks. A significant effect for group and modality and a significant interaction between group × modality were found, with lower visuotactile discrimination thresholds in the group with complete improvement to sensory tricks compared with the other groups. In primary cervical dystonia, a complete resolution of dystonia during a sensory trick is associated with better visuotactile discrimination and shorter disease duration compared with patients with less effective sensory tricks, which may reflect progressive loss of adaptive mechanisms to basal ganglia dysfunction.

Dual tasking affects gait performance but not automaticity in functional gait disorders: A new diagnostic biomarker.

INTRODUCTION: Functional gait disorders (FGDs) are disabling symptoms of Functional Motor Disorders. Clinical observations show improvement with distraction suggesting an association with higher-level control mechanisms. Dual tasking is a valuable tool for exploring the interplay between gait and cognition. Our research question was: how do different dual task paradigms shape spatio-temporal gait parameters in FGDs?. METHODS: In all, 29 patients with FGDs (age 43.48 ± 15.42 years; female 75%) and 49 healthy controls (age 43.33 ± 15.41 years; female 62%) underwent spatio-temporal gait analysis during a single task and during performance on a motor, a cognitive, and a visual-fixation dual-task. The dual-task effect was a measure of interference of the concurrent task on gait speed, stride length (a measure of gait performance), and stride time variability (a measure of automaticity and steadiness). RESULTS: Overall lower gait speed, shorter stride length, and higher stride time variability were noted in FGDs compared to healthy controls (for all, p < 0.019). The was a significant effect of group and Task × Group interaction for the dual-task effect on gait speed (p = 0.023) and stride length (p = 0.01) but not for stride time variability. CONCLUSION: Poorer gait performance and less automaticity and steadiness were noted in FGDs. However, dual tasking affected gait performance but, unlike different neurological diseases, not automaticity and steadiness compared to controls. Our findings shed light on higher-level gait control mechanisms in FGDs and suggest stride time variability could be a diagnostic and prognostic biomarker.