Speed-accuracy testing on the Apple iPad provides a quantitative test of upper extremity motor performance in children with dystonia

A Scoping Review on Mobile Health Technology for Assessment and Intervention of Upper Limb Motor Function in Children with Motor Impairments

Upper limb (UL) motor dysfunctions impact residual movement in hands/shoulders and limit participation in play, sports, and leisure activities. Clinical and laboratory assessments of UL movement can be time-intensive, subjective, and/or require specialized equipment and may not optimally capture a child's motor abilities. The restrictions to in-person research experienced during the COVID-19 pandemic have inspired investigators to design inclusive at-home studies with child participants and their families. Relying on the ubiquity of mobile devices, mobile health (mHealth) applications offer solutions for various clinical and research problems. This scoping review article aimed to aggregate and synthesize existing research that used health technology and mHealth approaches to evaluate and assess the hand function and UL movement in children with UL motor impairment. A scoping review based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) model was conducted in March 2023 yielding 25 articles (0.32% of 7891 studies). Assessment characteristics included game or task-based tests (13/25, 52%), primarily for neurological disorders (e.g., autism spectrum disorder [ASD], dystonia, dysgraphia) or children with cerebral palsy (CP). Although several mHealth studies were conducted in the clinical environment (10/25, 40%), studies conducted at home or in nonclinical settings (15/25, 60%) reported acceptable and highly satisfactory to the patients as minimizing the potential risks in participation. Moreover, the remaining barriers to clinical translation included object manipulation on a touch screen, offline data analysis, real-world usability, and age-appropriate application design for the wider population. However, the results emphasize the exploration of mHealth over traditional approaches, enabling user-centered study design, family-oriented methods, and large-scale sampling in future research.

Smartphone applications for Movement Disorders: Towards collaboration and re-use

BACKGROUND

Numerous smartphone and tablet applications (apps) are available to monitor movement disorders, but an overview of their purpose and stage of development is missing.

OBJECTIVES

To systematically review published literature and classify smartphone and tablet apps with objective measurement capabilities for the diagnosis, monitoring, assessment, or treatment of movement disorders.

METHODS

We systematically searched for publications covering smartphone or tablet apps to monitor movement disorders until November 22nd, 2023. We reviewed the target population, measured domains, purpose, and technology readiness level (TRL) of the proposed app and checked their availability in common app stores.

RESULTS

We identified 113 apps. Most apps were developed for Parkinson's disease specifically (n = 82; 73%) or for movement disorders in general (n = 17; 15%). Apps were either designed to momentarily assess symptoms (n = 65; 58%), support treatment (n = 22; 19%), aid in diagnosis (n = 16; 14%), or passively track symptoms (n = 11; 10%). Commonly assessed domains across movement disorders included fine motor skills (n = 34; 30%), gait (n = 36; 32%), and tremor (n = 32; 28%) for the motor domain and cognition (n = 16; 14%) for the non-motor domain. Twenty-six (23%) apps were proof-of-concepts (TRL 1-3), while most apps were tested in a controlled setting (TRL 4-6; n = 63; 56%). Twenty-four apps were tested in their target setting (TRL 7-9) of which 10 were accessible in common app stores or as Android Package.

CONCLUSIONS

The development of apps strongly gravitates towards Parkinson's disease and a selection of motor symptoms. Collaboration, re-use and further development of existing apps is encouraged to avoid reinventions of the wheel.

Reliability and validity of eye-hand coordination pointing tests for older adults

To examine the reliability and validity of eye-hand coordination pointing with pencil test (EHCPPT), which evaluates the spatial and temporal displacement of rhythmic movements. One hundred and thirty-five older adults participated in our study. Reproducibility of the EHCPPT was assessed by the participants tapping on the center of the circles using a tablet pen in response to 2 types of stimulus sound sequences (Test A and B) across 2 separate trials, the first and second half. Construct validity was assessed by comparison in the distances between ultimate and current processing abilities, based on the spatial and temporal displacement relationship across Test A and Test B. Concurrent validity was assessed by examining the relationship between the distances between ultimate and current processing abilities and the motor and cognitive functions. Spatial and temporal displacements showed an excellent intraclass correlation coefficient in both Tests A and B of EHCPPT. The distance between ultimate and current processing ability, based on the relationship of spatial and temporal displacement, was significantly shorter in Test A compared to Test B. Spatial and temporal displacements were correlated with motor and cognitive functions. The spatial and temporal displacements of EHCPPT indicated reproducibility and validity in older adults. The EHCPPT may serve as a rhythmic movement reflecting motor and cognitive functions.

Evaluation of Predictive Motor Control With Two Touchscreen Tablet-Based Tests: Reliability and Validity in School-Aged Children

As predictive motor control is an important index of neuromotor development and maturation, we developed two touchscreen tablet-based tests of this function. Our aim was to investigate the reliability and validity of both a rapid manual interception test and a pursuit tracking test, using a sample of 124 children (62 boys and 62 girls) from two age groups (7-8-year-oldss and 9-10-year-olds). Participants performed both tablet tests with a stylus (sample rate 100 Hz) with both a visible and a temporarily invisible moving target. Confirmatory factor analyses and omega coefficients showed that both tests were univariate methods that provided a reliable assessment of the latent factor related to predictive visuomotor control. As would be expected, compared to younger children, older children performed better on both manual interception and pursuit tracking. The correlations between the latent factors of the two tests at 95% confidence intervals (-.276, -.608) suggested shared variance. Thus, the touchscreen-tablet based tests of rapid manual interception and manual pursuit tracking appear psychometrically suitable for assessing the neuromotor ability of predictive control in 7-10-year-old children.

Assessing IQ in adolescents with mild to moderate cerebral palsy using the WISC-V

Objective: To examine the influence of subtests that require fine motor responses on measures of intellectual ability, and compare three approaches to minimizing motor demands while assessing cognitive abilities in adolescents with cerebral palsy (CP) to the traditional method of the Wechsler Intelligence Scale for Children - Fifth edition (WISC-V). Method: Seventy adolescents with CP (M = 14 years 6 months, SD = 10 months) who were able to provide either a verbal or point response were assessed using the WISC-V administered via Q-interactive. The pencil-to-paper version of Coding was also administered. Performance on Block Design and pencil-to-paper Coding was compared to Visual Puzzles and Coding on Q-interactive, respectively. Full Scale IQ (FSIQ) scores derived according to the Traditional method of the WISC-V were compared to alternative estimates of FSIQ derived according to the Q-interactive, Nonmotor, and Motor-free methods, which minimized motor demands. Results: An additional 7-12% of participants were able to respond to Visual puzzles and Coding on Q-interactive compared to Block Design and pencil-to-paper Coding, respectively, and performance was marginally but significantly better. For 54 adolescents (Gross Motor Function Classification System (GMFCS) Level I-III) who were able to obtain FSIQ scores, the Traditional method underestimated FSIQ by 3-6 points compared to the alternative methods and the difference was most pronounced for those with more severe CP as measured by the GMFCS. Conclusion: Adolescents with CP are at an inherent disadvantage when cognitive ability is assessed using the Traditional method of the WISC-V. Findings suggest clinicians should employ the Nonmotor or Motor-free methods when assessing IQ in adolescents with CP.

Combined effect of orthotic intervention and conventional exercise training on balance and gait performance in cerebral palsy: a randomized controlled trial

Background

This study aimed to examine the combined effect of orthotic intervention and conventional therapeutic exercise training on balance and gait performance in children with cerebral palsy. This study was a randomized control trial. Forty children with dyskinetic cerebral palsy of both genders with ages ranged from 12 to 16 years were included. Participants in the control and study groups received a conventional therapeutic exercise training program for two 2 h ours per session. The treatment program was conducted three sessions per week, for twelve 12 successive weeks. Children in the study group additionally wore TheraTogs orthotic undergarment with the strapping system. Pediatric Balance Scale score and postural stability indices (overall, anteroposterior , and mediolateral) evaluated by the Biodex Balance System were assessed (in both groups) at baseline and after 12 weeks of treatment. The changes of step length, gait cycle time, cadence, and velocity were also measured by an electronic walkway.

Results

Children in the study group showed significant improvements in the scores of all the measured variables post-treatment compared to the control group (P < 0.05). The P -values for overall, anteroposterior and mediolateral postural stability indices were 0.011, 0.014, and 0.021, respectively. The P -values for Pediatric Balance Scale score, step length, gait cycle time, cadence, and velocity were 0.001, 0.023, 0.041, 0.011, and 0.013 respectively.

Conclusions

Conventional therapeutic exercise training combined with orthotic intervention were more effective in improving balance and gait performance in children with dyskinetic cerebral palsy.

Trial registration

The ClinicalTrial.gov PRS (NCT04990193).

Registered 4 August 2021 - Retrospectively registered.

Evaluation of Child-Computer Interaction Using Fitts' Law: A Comparison between a Standard Computer Mouse and a Head Mouse

This study evaluates and compares the suitability for child-computer interaction (CCI, the branch within human-computer interaction focused on interactive computer systems for children) of two devices: a standard computer mouse and the ENLAZA interface, a head mouse that measures the user's head posture using an inertial sensor. A multidirectional pointing task was used to assess the motor performance and the users' ability to learn such a task. The evaluation was based on the interpretation of the metrics derived from Fitts' law. Ten children aged between 6 and 8 participated in this study. Participants performed a series of pre- and post-training tests for both input devices. After the experiments, data were analyzed and statistically compared. The results show that Fitts' law can be used to detect changes in the learning process and assess the level of psychomotor development (by comparing the performance of adults and children). In addition, meaningful differences between the fine motor control (hand) and the gross motor control (head) were found by comparing the results of the interaction using the two devices. These findings suggest that Fitts' law metrics offer a reliable and objective way of measuring the progress of physical training or therapy.

Can spatial filtering separate voluntary and involuntary components in children with dyskinetic cerebral palsy?

The design of myocontrolled devices faces particular challenges in children with dyskinetic cerebral palsy because the electromyographic signal for control contains both voluntary and involuntary components. We hypothesized that voluntary and involuntary components of movements would be uncorrelated and thus detectable as different synergistic patterns of muscle activity, and that removal of the involuntary components would improve online EMG-based control. Therefore, we performed a synergy-based decomposition of EMG-guided movements, and evaluated which components were most controllable using a Fitts' Law task. Similarly, we also tested which muscles were most controllable. We then tested whether removing the uncontrollable components or muscles improved overall function in terms of movement time, success rate, and throughput. We found that removal of less controllable components or muscles did not improve EMG control performance, and in many cases worsened performance. These results suggest that abnormal movement in dyskinetic CP is consistent with a pervasive distortion of voluntary movement rather than a superposition of separable voluntary and involuntary components of movement.

New modalities and directions for dystonia care

Dystonia is an abnormal involuntary movement or posture owing to sustained or intermittent muscle contraction. Standard treatment for dystonia includes medications, such as levodopa, anticholinergic and antiepileptic drugs, botulinum toxin, and baclofen pump, and surgeries, such as lesioning surgery and deep-brain stimulation. New treatment modalities aimed toward improving dystonia care in the future are under investigation. There are two main axes to improve dystonia care; one is non-invasive neuromodulation, such as transcranial magnetic stimulation, transcranial electrical stimulation, and transcutaneous electrical nerve stimulation. The other is a quantitative evaluation of dystonia using a wearable device and motion-capturing system, which can be empowered by artificial intelligence. In this article, the current status of these axes will be reviewed.

Neuromorphic Model of Reflex for Realtime Human-Like Compliant Control of Prosthetic Hand

Current control of prosthetic hands is ineffective when grasping deformable, irregular, or heavy objects. In humans, grasping is achieved under spinal reflexive control of the musculotendon skeletal structure, which produces a hand stiffness commensurate with the task. We hypothesize that mimicking reflex on a prosthetic hand may improve grasping performance and safety when interacting with human. Here, we present a design of compliant controller for prosthetic hand with a neuromorphic model of human reflex. The model includes 6 motoneuron pools containing 768 spiking neurons, 1 muscle spindle with 128 spiking afferents, and 1 modified Hill-type muscle. Models are implemented using neuromorphic hardware with 1 kHz real-time computing. Experimental tests showed that the prosthetic hand could sustain a 40 N load compared to 95 N for an adult. Stiffness range was adjustable from 60 to 640 N/m, about 46.6% of that of human hand. The grasping velocity could be ramped up to 14.4 cm/s, or 24% of the human peak velocity. The complaint control could switch between free movement and contact force when pressing a deformable beam. The amputee can achieve a 47% information throughput of healthy humans. Overall, the reflex-enabled prosthetic hand demonstrated the attributes of human compliant grasping with the neuromorphic model of spinal neuromuscular reflex.

Instrumented assessment of motor function in dyskinetic cerebral palsy: a systematic review

BACKGROUND

In this systematic review we investigate which instrumented measurements are available to assess motor impairments, related activity limitations and participation restrictions in children and young adults with dyskinetic cerebral palsy. We aim to classify these instrumented measurements using the categories of the international classification of functioning, disability and health for children and youth (ICF-CY) and provide an overview of the outcome parameters.

METHODS

A systematic literature search was performed in November 2019. We electronically searched Pubmed, Embase and Scopus databases. Search blocks included (a) cerebral palsy, (b) athetosis, dystonia and/or dyskinesia, (c) age 2-24 years and (d) instrumented measurements (using keywords such as biomechanics, sensors, smartphone, and robot).

RESULTS

Our search yielded 4537 articles. After inspection of titles and abstracts, a full text of 245 of those articles were included and assessed for further eligibility. A total of 49 articles met our inclusion criteria. A broad spectrum of instruments and technologies are used to assess motor function in dyskinetic cerebral palsy, with the majority using 3D motion capture and surface electromyography. Only for a small number of instruments methodological quality was assessed, with only one study showing an adequate assessment of test-retest reliability. The majority of studies was at ICF-CY function and structure level and assessed control of voluntary movement (29 of 49) mainly in the upper extremity, followed by assessment of involuntary movements (15 of 49), muscle tone/motor reflex (6 of 49), gait pattern (5 of 49) and muscle power (2 of 49). At ICF-CY level of activities and participation hand and arm use (9 of 49), fine hand use (5 of 49), lifting and carrying objects (3 of 49), maintaining a body position (2 of 49), walking (1 of 49) and moving around using equipment (1 of 49) was assessed. Only a few methods are potentially suitable outside the clinical environment (e.g. inertial sensors, accelerometers).

CONCLUSION

Although the current review shows the potential of several instrumented methods to be used as objective outcome measures in dyskinetic cerebral palsy, their methodological quality is still unknown. Future development should focus on evaluating clinimetrics, including validating against clinical meaningfulness. New technological developments should aim for measurements that can be applied outside the laboratory.

Portable Motion-Analysis Device for Upper-Limb Research, Assessment, and Rehabilitation in Non-Laboratory Settings

This study presents the design and feasibility testing of an interactive portable motion-analysis device for the assessment of upper-limb motor functions in clinical and home settings. The device engages subjects to perform tasks that imitate activities of daily living, e.g. drinking from a cup and moving other complex objects. Sitting at a magnetic table subjects hold a 3D printed cup with an adjustable magnet and move this cup on the table to targets that can be drawn on the table surface. A ball rolling inside the cup can enhance the task challenge by introducing additional dynamics. A single video camera with a portable computer tracks real-time kinematics of the cup and the rolling ball using a custom-developed, color-based computer-vision algorithm. Preliminary verification with marker-based 3D-motion capture demonstrated that the device produces accurate kinematic measurements. Based on the real-time 2D cup coordinates, audio-visual feedback about performance can be delivered to increase motivation. The feasibility of using this device in clinical diagnostics is demonstrated on 2 neurotypical children and also 3 children with upper-extremity impairments in the hospital, where conventional motion-analysis systems are difficult to use. The device meets key needs for clinical practice: 1) a portable solution for quantitative motor assessment for upper-limb movement disorders at non-laboratory clinical settings, 2) a low-cost rehabilitation device that can increase the volume of in-home physical therapy, and 3) the device affords testing and training a variety of motor tasks inspired by daily challenges to enhance self-confidence to participate in day-to-day activities.

A Model to Estimate the Optimal Layout for Assistive Communication Touchscreen Devices in Children With Dyskinetic Cerebral Palsy

Excess involuntary movements and slowness of movement in children with dyskinetic cerebral palsy often result in the inability to properly interact with augmentative and alternative communication (AAC) devices. This significantly limits communication. It is, therefore, essential to know how to adjust the device layout in order to maximize each child's rate of communication. The aim of this paper was to develop a mathematical model to estimate the information rate in children with dyskinetic cerebral palsy and to determine the optimal AAC layout for a touchscreen tablet that results in enhanced speed of communication. The model predicts information rate based on button size, number, spacing between buttons, and the probability of making an error or missing target buttons. Estimation of the information rate confirmed our hypothesis of lower channel capacity in children with dyskinetic cerebral palsy compared with age-matched healthy children. Information rate increased when the AAC layout was customized based on the optimal parameters predicted by the model. In conclusion, this paper quantifies the effect of motor impairments on communication with assistive communication devices and shows that communication performance can be improved by optimally matching the parameters of the AAC touchscreen device to the abilities of the child.

Quantification of Upper-Extremity Movement Pattern in Patients with Stroke using Touchscreen: A Pilot Study

Humans typically move slower if the movement needs to be more accurate. Such a tradeoff between movement speed and accuracy is quantified in Fitts' Law as a linear relationship between the movement time (MT) and the index of difficulty (ID). For patients with stroke, the detailed pattern of speed-accuracy tradeoff is likely affected due to disrupted neuromuscular control in stroke. In this study, we adapted a previously published iPad software program designed for the test of Fitts' Law in children with dystonia. Subjects were asked to touch targets with different sizes and distances on the touchscreen. Data from 3 patients with stroke suggest that the post-stroke upper-extremity movements still obey Fitts' Law, but the affected side showed larger slopes, and higher endpoint errors compared with the unaffected side. Moreover, the success rate in the affected side was significantly higher than healthy controls, but not than the unaffected side. Our preliminary data suggest that Fitts' Law provides a promising toolkit for quantitatively assessing the movement behavior in stroke.

Basic and Translational Neuroscience of Childhood-Onset Dystonia: A Control-Theory Perspective

Dystonia is a collection of symptoms with involuntary muscle activation causing hypertonia, hyperkinetic movements, and overflow. In children, dystonia can have numerous etiologies with varying neuroanatomic distribution. The semiology of dystonia can be explained by gain-of-function failure of a feedback controller that is responsible for stabilizing posture and movement. Because postural control is maintained by a widely distributed network, many different anatomic regions may be responsible for symptoms of dystonia, although all features of dystonia can be explained by uncontrolled activation or hypersensitivity of motor cortical regions that can cause increased reflex gain, inserted postures, or sensitivity to irrelevant sensory variables. Effective treatment of dystonia in children requires an understanding of the relationship between etiology, anatomy, and the specific mechanism of failure of postural stabilization.

Mobile applications in children with cerebral palsy

INTRODUCTION

Cerebral palsy (CP) is one of the most common developmental disorders. Technological development has enabled a transformation of the healthcare sector, which can offer more individualised, participatory, and preventive services. Within this context of new technology applied to the healthcare sector, mobile applications, or apps, constitute a very promising tool for the management of children with CP.

OBJECTIVE

The purpose of this article is to perform a systematic review of the information published about various mobile applications either directly related to CP or with potential to be useful in the context of the disease, and to describe, analyse, and classify these applications.

MATERIAL AND METHODS

A literature search was carried out to gather articles published in English or Spanish between 2011 and 2017 which presented, analysed, or validated applications either specifically designed or potentially useful for CP. Furthermore, a search for mobile applications was conducted in the main mobile application markets.

CONCLUSIONS

A total of 63 applications were found in biomedical databases and mobile application markets, of which 40 were potentially useful for CP and 23 were specifically designed for the condition (11 for information, 3 for evaluation, and 9 for treatment). There are numerous mobile applications either specifically designed for or with potential to be useful in the field of CP. However, despite the existing scientific evidence, the low methodological quality of scientific articles makes it impossible to generalise the use of these tools.

Intrathecal baclofen therapy in paediatrics: a study protocol for an Australian multicentre, 10-year prospective audit

INTRODUCTION

Increasing clinical use of Intrathecal baclofen (ITB) in Australian tertiary paediatric hospitals, along with the need for standardised assessment and reporting of adverse events, saw the formation of the Australian Paediatric ITB Research Group (APIRG). APIRG developed a National ITB Audit tool designed to capture clinical outcomes and adverse events data for all Australian children and adolescents receiving ITB therapy.

METHODS AND ANALYSIS

The Australian ITB Audit is a 10 year, longitudinal, prospective, clinical audit collecting all adverse events and assessment data across body functions and structure, participation and activity level domains of the ICF. Data will be collected at baseline, 6 and 12 months with ongoing capture of all adverse event data. This is the first Australian study that aims to capture clinical and adverse event data from a complete population of children with neurological impairment receiving a specific intervention between 2011 and 2021. This multi-centre study will inform ITB clinical practice in children and adolescents, direct patient selection, record and aid decision making regarding adverse events and investigate the impact of ITB therapy on family and patient quality of life.

ETHICS AND DISSEMINATION

This project was approved by the individual Human Research Ethics committees at the six Australian tertiary hospitals involved in the study. Results will be published in various peer reviewed journals and presented at national and international conferences.

TRIAL REGISTRATION NUMBER

ACTRN 12610000323022; Pre-results.

Scaled Vibratory Feedback Can Bias Muscle Use in Children With Dystonia During a Redundant, 1-Dimensional Myocontrol Task

Vibratory feedback can be a useful tool for rehabilitation. We examined its use in children with dystonia to understand how it affects muscle activity in a population that does not respond well to standard rehabilitation. We predicted scaled vibration (ie, vibration that was directly or inversely proportional to muscle activity) would increase use of the vibrated muscle because of task-relevant sensory information, whereas nonscaled vibration would not change muscle use. The study was conducted on 11 subjects with dystonia and 14 controls. Each subject underwent 4 different types of vibration on the more dystonic biceps muscle (or nondominant arm in controls) in a 1-dimensional, bimanual myocontrol task. Our results showed that only scaled vibratory feedback could bias muscle use without changing overall performance in children with dystonia. We believe there may be a role in rehabilitation for scaled vibratory feedback to retrain abnormal muscle patterns.

Perceived Cost and Intrinsic Motor Variability Modulate the Speed-Accuracy Trade-Off

Fitts’ Law describes the speed-accuracy trade-off of human movements, and it is an elegant strategy that compensates for random and uncontrollable noise in the motor system. The control strategy during targeted movements may also take into account the rewards or costs of any outcomes that may occur. The aim of this study was to test the hypothesis that movement time in Fitts’ Law emerges not only from the accuracy constraints of the task, but also depends on the perceived cost of error for missing the targets. Subjects were asked to touch targets on an iPad^® screen with different costs for missed targets. We manipulated the probability of error by comparing children with dystonia (who are characterized by increased intrinsic motor variability) to typically developing children. The results show a strong effect of the cost of error on the Fitts’ Law relationship characterized by an increase in movement time as cost increased. In addition, we observed a greater sensitivity to increased cost for children with dystonia, and this behavior appears to minimize the average cost. The findings support a proposed mathematical model that explains how movement time in a Fitts-like task is related to perceived risk.

Speed-Accuracy Trade-Off in a Trajectory-Constrained Self-Feeding Task: A Quantitative Index of Unsuppressed Motor Noise in Children With Dystonia

Motor speed and accuracy are both affected in childhood dystonia. Thus, deriving a speed-accuracy function is an important metric for assessing motor impairments in dystonia. Previous work in dystonia studied the speed-accuracy trade-off during point-to-point tasks. To achieve a more relevant measurement of functional abilities in dystonia, the present study investigates upper-limb kinematics and electromyographic activity of 8 children with dystonia and 8 healthy children during a trajectory-constrained child-relevant task that emulates self-feeding with a spoon and requires continuous monitoring of accuracy. The speed-accuracy trade-off is examined by changing the spoon size to create different accuracy demands. Results demonstrate that the trajectory-constrained speed-accuracy relation is present in both groups, but it is altered in dystonia in terms of increased slope and offset toward longer movement times. Findings are consistent with the hypothesis of increased signal-dependent noise in dystonia, which may partially explain the slow and variable movements observed in dystonia.

Increased task-uncorrelated muscle activity in childhood dystonia

BACKGROUND

Even if movement abnormalities in dystonia are obvious on observation-based examinations, objective measures to characterize dystonia and to gain insights into its pathophysiology are still strongly needed. We hypothesize that motor abnormalities in childhood dystonia are partially due to the inability to suppress involuntary variable muscle activity irrelevant to the achievement of the desired motor task, resulting in the superposition of unwanted motion components on the desired movement. However, it is difficult to separate and quantify appropriate and inappropriate motor signals combined in the same muscle, especially during movement.

METHODS

We devise an innovative and practical method to objectively measure movement abnormalities during the performance of a continuous figure-eight writing task in 7 children with dystonia and 9 age-matched healthy controls. During the execution of a continuous writing task, muscle contractions should occur at frequencies that match the frequencies of the writing outcome. We compare the power spectra of kinematic trajectories and electromyographic signals of 8 upper limb muscles to separate muscle activity with the same frequency content of the figure-eight movement (task-correlated) from activity occurring at frequencies extraneous to the task (task-uncorrelated).

RESULTS

Children with dystonia present a greater magnitude of task-uncorrelated muscle components. The motor performance achieved by children with dystonia is characterized by an overall lower quality, with high spatial and temporal variability and an altered trade-off between speed and accuracy.

CONCLUSIONS

Findings are consistent with the hypothesis that, in childhood dystonia, the ability to appropriately suppress variable and uncorrelated elements of movement is impaired. Here we present a proof-of-concept of a promising tool to characterize the phenomenology of movement disorders and to inform the design of neurorehabilitation therapies.

Current and emerging strategies for treatment of childhood dystonia

Childhood dystonia is a movement disorder characterized by involuntary sustained or intermittent muscle contractions causing twisting and repetitive movements, abnormal postures, or both (Sanger et al, 2003). Dystonia is a devastating neurological condition that prevents the acquisition of normal motor skills during critical periods of development in children. Moreover, it is particularly debilitating in children when dystonia affects the upper extremities such that learning and consolidation of common daily motor actions are impeded. Thus, the treatment and rehabilitation of dystonia is a challenge that continuously requires exploration of novel interventions. This review will initially describe the underlying neurophysiological mechanisms of the motor impairments found in childhood dystonia followed by the clinical measurement tools that are available to document the presence and severity of symptoms. Finally, we will discuss the state-of-the-art of therapeutic options for childhood dystonia, with particular emphasis on emergent and innovative strategies.

Validating the Accuracy of Reaction Time Assessment on Computer-Based Tablet Devices

Computer-based assessment has evolved to tablet-based devices. Despite the availability of tablets and "apps," there is limited research validating their use. We documented timing delays between stimulus presentation and (simulated) touch response on iOS devices (3rd- and 4th-generation Apple iPads) and Android devices (Kindle Fire, Google Nexus, Samsung Galaxy) at response intervals of 100, 250, 500, and 1,000 milliseconds (ms). Results showed significantly greater timing error on Google Nexus and Samsung tablets (81-97 ms), than Kindle Fire and Apple iPads (27-33 ms). Within Apple devices, iOS 7 obtained significantly lower timing error than iOS 6. Simple reaction time (RT) trials (250 ms) on tablet devices represent 12% to 40% error (30-100 ms), depending on the device, which decreases considerably for choice RT trials (3-5% error at 1,000 ms). Results raise implications for using the same device for serial clinical assessment of RT using tablets, as well as the need for calibration of software and hardware.