Remotely prescribed and monitored home-based gait-and-balance therapeutic exergaming using augmented reality (AR) glasses: protocol for a clinical feasibility study in people with Parkinson's disease.

BACKGROUND: Clinical guidelines for people with Parkinson's disease (pwPD) stress that, complementary to pharmacological treatment, exercise and physiotherapy should be given a central role in disease management. Adhering to regular exercise of the right type, and with high repetition, remains a challenge for pwPD. Exergaming has the potential to increase adherence through play and personalised interventions, both in clinic and at home. Reality DTx® is an augmented-reality (AR) home-based gait-and-balance exergaming intervention specifically designed for pwPD as an extension of supervised physiotherapy. The primary objective of this study is to evaluate the feasibility and potential efficacy of Reality DTx®. METHODS: Twenty-four pwPD (Hoehn and Yahr stages 2-4) with self-reported gait and/or balance impairments will participate in this study. The study comprises a 6-week waitlist-controlled AR home-based therapeutic gait-and-balance exergaming intervention. Reality DTx® will initially be prescribed remotely for a minimum of 5 days a week for 30 min per day. We will remotely set and adjust the frequency, difficulty, type of games, and/or duration weekly, based on objective and subjective data from the AR glasses and participant, respectively. In addition to the home-based gait-and-balance exergaming intervention, the study comprises three laboratory visits: before the 6-week waitlist period (t0; baseline), before the 6-week intervention period (t1; pre-intervention), and after the 6-week intervention period (t2; post-intervention). The primary study parameters are feasibility (in terms of safety, adherence, and user experience) and potential efficacy for improving gait and balance (using standard clinical gait-and-balance tests and a targeted walking-related fall-risk assessment). Recruitment started in December 2022 and the final post-intervention assessment will be according to planning in July 2023. CONCLUSIONS: This clinical feasibility trial is the first remotely prescribed and monitored home-based AR gait-and-balance exergaming intervention for pwPD. The results in terms of clinical feasibility (i.e. safety, adherence, and user experience) and potential efficacy (gait, balance, and fall-risk outcomes) form the basis for future randomised controlled studies on the effectiveness of home-based AR gait-and-balance exergaming interventions for pwPD. TRIAL REGISTRATION: ClinicalTrials.gov, NCT05605249 . Registered on 4 November 2022.

Clinical neurophysiology of functional motor disorders: IFCN Handbook Chapter.

Functional Motor Disorders are common and disabling. Clinical diagnosis has moved from one of exclusion of other causes for symptoms to one where positive clinical features on history and examination are used to make a "rule in" diagnosis wherever possible. Clinical neurophysiological assessments have developed increasing importance in assisting with this positive diagnosis, not being used simply to demonstrate normal sensory-motor pathways, but instead to demonstrate specific abnormalities that help to positively diagnose these disorders. Here we provide a practical review of these techniques, their application, interpretation and pitfalls. We also highlight particular areas where such tests are currently lacking in sensitivity and specificity, for example in people with functional dystonia and functional tic-like movements.

The Use of the Voice Trainer App for Vocal Control in People with a Degenerative Ataxia: A Pilot Intervention Study.

Dysarthria is disabling in persons with degenerative ataxia. There is limited evidence for speech therapy interventions. In this pilot study, we used the Voice trainer app, which was originally developed for patients with Parkinson's disease, as a feedback tool for vocal control. We hypothesized that patients with ataxic dysarthria would benefit from the Voice trainer app to better control their loudness and pitch, resulting in a lower speaking rate and better intelligibility. This intervention study consisted of five therapy sessions of 30 min within 3 weeks using the principles of the Pitch Limiting Voice Treatment. Patients received real-time visual feedback on loudness and pitch during the exercises. Besides, they were encouraged to practice at home or to use the Voice trainer in daily life. We used observer-rated and patient-rated outcome measures. The primary outcome measure was intelligibility, as measured by the Dutch sentence intelligibility test. Twenty-one out of 25 included patients with degenerative ataxia completed the therapy. We found no statistically significant improvements in intelligibility (p = .56). However, after the intervention, patients were speaking slower (p = .03) and the pause durations were longer (p < .001). The patients were satisfied about using the app. At the group level, we found no evidence for an effect of the Voice trainer app on intelligibility in degenerative ataxia. Because of the heterogeneity of ataxic dysarthria, a more tailor-made rather than generic intervention seems warranted.

Good vibrations: tactile cueing for freezing of gait in Parkinson's disease.

BACKGROUND: Cueing strategies can alleviate freezing of gait (FOG) in people with Parkinson's disease (PD). We evaluated tactile cueing delivered via vibrating socks, which has the benefit of not being noticeable to bystanders. OBJECTIVE: To evaluate the effect of tactile cueing compared to auditory cueing on FOG. METHODS: Thirty-one persons with PD with FOG performed gait tasks during both ON and OFF state. The effect of open loop and closed loop tactile cueing, as delivered by vibrating socks, was compared to an active control group (auditory cueing) and to a baseline condition (uncued gait). These four conditions were balanced between subjects. Gait tasks were videotaped and annotated for FOG by two experienced raters. Motion data were collected to analyze spatiotemporal gait parameters. Responders were defined as manifesting a relative reduction of > 10% in the percent time frozen compared to uncued gait. RESULTS: The average percent time frozen during uncued gait was 11.2% in ON and 21.5% in OFF state. None of the three tested cueing modalities affected the percentage of time frozen in either the ON (p = 0.20) or OFF state (p = 0.12). The number of FOG episodes and spatiotemporal gait parameters were also not affected. We found that 22 out of 31 subjects responded to cueing, the response to the three types of cueing was highly individual. CONCLUSIONS: Cueing did not improve FOG at the group level; however, tactile as well as auditory cueing improved FOG in many individuals. This highlights the need for a personalized approach when using cueing to treat FOG.

Validation of the Auditory Stroop Task to increase cognitive load in walking tasks in healthy elderly and persons with Parkinson's disease.

BACKGROUND: The development of treatments for freezing of gait (FOG) in Parkinson's disease (PD) requires experimental study set-ups in which FOG is likely to occur, and is amenable to therapeutic interventions. We explore whether the 'Auditory Stroop Task' (AST) can be used to increase cognitive load (and thereby elicit FOG), simultaneously with visual cues (as a therapeutic intervention for FOG). We additionally examined how these two contrasting effects might interact in affecting gait and FOG parameters. OBJECTIVES: We investigated whether: (1) the 'Auditory Stroop Task' (AST) influences gait in healthy elderly and persons with PD who experience FOG, and increases the frequency of FOG events among PD patients; (2) the AST and visual cues interact; and (3) different versions of the AST exert different cognitive loads. METHODS: In 'Experiment 1', 19 healthy elderly subjects performed a walking task while performing a high and low load version of the AST. Walking with a random numbers task, and walking without cognitive load served as control conditions. In 'Experiment 2', 20 PD patients with FOG and 18 healthy controls performed a walking task with the AST, and no additional cognitive load as control condition. Both experiments were performed with and without visual cues. Velocity, cadence, stride length, and stride time were measured in all subjects. FOG severity was measured in patients. RESULTS: Compared to the control conditions, the AST negatively affected all gait parameters in both patients and controls. The AST did not increase the occurrence of FOG in patients. Visual cues reduced the decline in stride length induced by cognitive load in both groups. Both versions of the AST exerted similar effects on gait parameters in controls. CONCLUSIONS: The AST is well-suited to simulate the effects of cognitive load on gait parameters, but not FOG severity, in gait experiments in persons with PD and FOG.

Focus on the pedunculopontine nucleus. Consensus review from the May 2018 brainstem society meeting in Washington, DC, USA.

The pedunculopontine nucleus (PPN) is located in the mesopontine tegmentum and is best delimited by a group of large cholinergic neurons adjacent to the decussation of the superior cerebellar peduncle. This part of the brain, populated by many other neuronal groups, is a crossroads for many important functions. Good evidence relates the PPN to control of reflex reactions, sleep-wake cycles, posture and gait. However, the precise role of the PPN in all these functions has been controversial and there still are uncertainties in the functional anatomy and physiology of the nucleus. It is difficult to grasp the extent of the influence of the PPN, not only because of its varied functions and projections, but also because of the controversies arising from them. One controversy is its relationship to the mesencephalic locomotor region (MLR). In this regard, the PPN has become a new target for deep brain stimulation (DBS) for the treatment of parkinsonian gait disorders, including freezing of gait. This review is intended to indicate what is currently known, shed some light on the controversies that have arisen, and to provide a framework for future research.

Promising non-pharmacological therapies in PD: Targeting late stage disease and the role of computer based cognitive training.

Non-pharmacological interventions are increasingly being acknowledged as valuable treatment options to overcome or reduce functional problems in patients with Parkinson's disease (PD). There is a wide range of such non-pharmacological treatments for which the supportive evidence is emerging. Physiotherapy is one good example in this domain. However, there are also several promising non-pharmacological treatment strategies that have thus far received less research attention. Here, we describe two relatively new, but encouraging approaches. First, we focus on a hitherto largely overseen subgroup of PD, namely those with late-stage disease, a population that is often excluded from clinical studies. Importantly, the aims and therapeutic strategies in late-stage PD differ considerably from those in early-stage PD, and an emphasis on non-pharmacological management is particularly important for this vulnerable subgroup. Second, we focus on computer-based cognitive training, as an example of a relatively new intervention that includes innovative elements such as personalized training, artificial intelligence, and virtual reality. We review the latest evidence, practical considerations and future research perspectives, both for non-pharmacological approaches in late-stage PD and for computer-based cognitive training.

Are postural responses to backward and forward perturbations processed by different neural circuits?

Startle pathways may contribute to rapid accomplishment of postural stability. Here we investigate the possible influence of a startling auditory stimulus (SAS) on postural responses. We formulated four specific questions: (1) can a concurrent SAS shorten the onset of automatic postural responses?; and if so (2) is this effect different for forward versus backward perturbations?; (3) does this effect depend on prior knowledge of the perturbation direction?; and (4) is this effect different for low- and high-magnitude perturbations? Balance was perturbed in 11 healthy participants by a movable platform that suddenly translated forward or backward. Each participant received 160 perturbations, 25% of which were combined with a SAS. We varied the direction and magnitude of the perturbations, as well as the prior knowledge of perturbation direction. Perturbation trials were interspersed with SAS-only trials. The SAS accelerated and strengthened postural responses with clear functional benefits (better balance control), but this was only true for responses that protected against falling backwards (i.e. in tibialis anterior and rectus femoris). These muscles also demonstrated the most common SAS-triggered responses without perturbation. Increasing the perturbation magnitude accelerated postural responses, but again with a larger acceleration for backward perturbations. We conclude that postural responses to backward and forward perturbations may be processed by different neural circuits, with influence of startle pathways on postural responses to backward perturbations. These findings give directions for future studies investigating whether deficits in startle pathways may explain the prominent backward instability seen in patients with Parkinson's disease and progressive supranuclear palsy.

Loading enhances the occurrence of startle responses in leg muscles.

INTRODUCTION: The startle reflex is an involuntary reaction to sudden sensory input and consists of a generalized flexion response. Startle responses in distal leg muscles occur more frequently during standing compared to sitting. We hypothesized that sensory input from load receptors modulates the occurrence of startle responses in leg muscles. METHODS: We administered sudden startling auditory stimuli (SAS) to 11 healthy subjects while (1) sitting relaxed, (2) standing relaxed, (3) standing while bearing 60% of their weight on the right leg, (4) standing while bearing 60% of their weight on the left leg, and (5) standing with 30% body weight support ('bilateral unloaded'). The requested weight distribution for each condition was verified using force plates. Electromyography data were collected from both tibialis anterior (TA) and the left sternocleidomastoid muscles. RESULTS: In the TA, startle responses occurred much more frequently during normal standing (26% of trials) compared to both sitting (6% of trials, p<0.01) and bilateral unloading (3% of trials, p<0.01). In the asymmetrical stance conditions, startle responses in the TA were more common in the loaded leg (21% of trials) compared to the unloaded leg (10% of trials, p<0.05). DISCUSSION: The occurrence of startle responses in the leg muscles was strongly influenced by load. Hence, it is likely that information from load receptors influences startle response activity. We suggest that, in a stationary position, startling stimuli result in a descending volley from brainstem circuits, which is gated at the spinal level by afferent input from load receptors.