Quantitative DigitoGraphy: a Comprehensive Real-Time Remote Monitoring System for Parkinson's Disease.

People with Parkinson's disease (PWP) face critical challenges, including lack of access to neurological care, inadequate measurement and communication of motor symptoms, and suboptimal medication management and compliance. We have developed QDG-Care: a comprehensive connected care platform for Parkinson's disease (PD) that delivers validated, quantitative metrics of all motor signs in PD in real time, monitors the effects of adjusting therapy and medication adherence and is accessible in the electronic health record. In this article, we describe the design and engineering of all components of QDG-Care, including the development and utility of the QDG Mobility and Tremor Severity Scores. We present the preliminary results and insights from the first at-home trial using QDG-Care. QDG technology has enormous potential to improve access to, equity of, and quality of care for PWP, and improve compliance with complex time-critical medication regimens. It will enable rapid "Go-NoGo" decisions for new therapeutics by providing high-resolution data that require fewer participants at lower cost and allow more diverse recruitment.

Differential Effects of Pathological Beta Burst Dynamics Between Parkinson's Disease Phenotypes Across Different Movements.

Background: Resting state beta band (13-30 Hz) oscillations represent pathological neural activity in Parkinson's disease (PD). It is unknown how the peak frequency or dynamics of beta oscillations may change among fine, limb, and axial movements and different disease phenotypes. This will be critical for the development of personalized closed loop deep brain stimulation (DBS) algorithms during different activity states. Methods: Subthalamic (STN) and local field potentials (LFPs) were recorded from a sensing neurostimulator (Activa® PC + S, Medtronic PLC.) in fourteen PD participants (six tremor-dominant and eight akinetic-rigid) off medication/off STN DBS during 30 s of repetitive alternating finger tapping, wrist-flexion extension, stepping in place, and free walking. Beta power peaks and beta burst dynamics were identified by custom algorithms and were compared among movement tasks and between tremor-dominant and akinetic-rigid groups. Results: Beta power peaks were evident during fine, limb, and axial movements in 98% of movement trials; the peak frequencies were similar during each type of movement. Burst power and duration were significantly larger in the high beta band, but not in the low beta band, in the akinetic-rigid group compared to the tremor-dominant group. Conclusion: The conservation of beta peak frequency during different activity states supports the feasibility of patient-specific closed loop DBS algorithms driven by the dynamics of the same beta band during different activities. Akinetic-rigid participants had greater power and longer burst durations in the high beta band than tremor-dominant participants during movement, which may relate to the difference in underlying pathophysiology between phenotypes.

Perspective: Evolution of Control Variables and Policies for Closed-Loop Deep Brain Stimulation for Parkinson's Disease Using Bidirectional Deep-Brain-Computer Interfaces.

A deep brain stimulation system capable of closed-loop neuromodulation is a type of bidirectional deep brain-computer interface (dBCI), in which neural signals are recorded, decoded, and then used as the input commands for neuromodulation at the same site in the brain. The challenge in assuring successful implementation of bidirectional dBCIs in Parkinson's disease (PD) is to discover and decode stable, robust and reliable neural inputs that can be tracked during stimulation, and to optimize neurostimulation patterns and parameters (control policies) for motor behaviors at the brain interface, which are customized to the individual. In this perspective, we will outline the work done in our lab regarding the evolution of the discovery of neural and behavioral control variables relevant to PD, the development of a novel personalized dual-threshold control policy relevant to the individual's therapeutic window and the application of these to investigations of closed-loop STN DBS driven by neural or kinematic inputs, using the first generation of bidirectional dBCIs.

Gender Differences in Modifying Lumbopelvic Motion during Hip Medial Rotation in People with Low Back Pain.

Reducing increased or early lumbopelvic motion during trunk or limb movements may be an important component of low back pain treatment. The ability to reduce lumbopelvic motion may be influenced by gender. The purpose of the current study was to examine the effect of gender on the ability of people with low back pain to reduce lumbopelvic motion during hip medial rotation following physical therapy treatment. Lumbopelvic rotation and hip rotation before the start of lumbopelvic rotation were assessed pre- and posttreatment for 16 females and 15 males. Both men and women decreased lumbopelvic rotation and completed more hip rotation before the start of lumbopelvic rotation post-treatment compared to pre-treatment. Men demonstrated greater lumbopelvic rotation and completed less hip rotation before the start of lumbopelvic rotation than women both pre- and post-treatment. Both men and women reduced lumbopelvic motion relative to their starting values, but, overall, men still demonstrated greater and earlier lumbopelvic motion. These results may have important implications for understanding differences in the evaluation and treatment of men and women with low back pain.

Differences in end-range lumbar flexion during slumped sitting and forward bending between low back pain subgroups and genders.

Patterns of lumbar posture and motion are associated with low back pain (LBP). Research suggests LBP subgroups demonstrate different patterns during common tasks. This study assessed differences in end-range lumbar flexion during two tasks between two LBP subgroups classified according to the Movement System Impairment model. Additionally, the impact of gender differences on subgroup differences was assessed. Kinematic data were collected. Subjects in the Rotation (Rot) and Rotation with Extension (RotExt) LBP subgroups were asked to sit slumped and bend forward from standing. Lumbar end-range flexion was calculated. Subjects reported symptom behaviour during each test. Compared to the RotExt subgroup, the Rot subgroup demonstrated greater end-range lumbar flexion during slumped sitting and a trend towards greater end-range lumbar flexion with forward bending. Compared to females, males demonstrated greater end-range lumbar flexion during slumped sitting and forward bending. A greater proportion of people in the Rot subgroup reported symptoms with each test compared to the RotExt subgroup. Males and females were equally likely to report symptoms with each test. Gender differences were not responsible for LBP subgroup differences. Subgrouping people with LBP provides insight into differences in lumbar motion within the LBP population. Results suggesting potential consistent differences across flexion-related tasks support the presence of stereotypical movement patterns that are related to LBP.

Clinical examination procedures to determine the effect of axial decompression on low back pain symptoms in people with chronic low back pain.

STUDY DESIGN: Observational. OBJECTIVE: To assess the effects of spinal decompression procedures performed during a clinical exam on low back pain (LBP) symptoms. BACKGROUND: Not all patients report an immediate or complete improvement in symptoms when the direction of lumbar motion or alignment is corrected according to principles of the movement system impairment (MSI) model. Axial compression of the spine may be responsible for the remaining symptoms. METHODS: Seventy subjects (mean ± SD age, 41.9 ± 11.5 years; 38 females, 32 males) with chronic LBP were evaluated using a standardized MSI exam. Seven tests assessing the effects of spinal decompression on LBP were added to the exam if the subjects' symptoms were not alleviated with typical standardized corrections of movement and alignment. For each test of decompression, subjects reported their symptoms compared to a reference movement or position. RESULTS: When decompression was performed during lateral bending to the right and left, 21 of 21 (100%) and 16 of 20 (80%) subjects, respectively, reported an improvement. When traction was applied to subjects in right and left sidelying, 6 of 11 (55%) and 7 of 9 (78%), respectively, reported an improvement. When patients performed a push-up in sitting, 36 of 51 (71%) reported an improvement. In subjects who had symptoms in unsupported sitting, 41 of 57 (72%) reported an improvement in supported sitting. In subjects who reported symptoms in standing, 33 of 47 (70%) reported an improvement in hook-lying. CONCLUSION: Patients with chronic LBP consistently reported an improvement in symptoms with tests proposed to decrease the axial load on the spine. These tests are a quick and effective way to assess the contribution of axial decompression to LBP symptoms and potentially could be used as part of the plan of care.

Sex differences in lumbopelvic movement patterns during hip medial rotation in people with chronic low back pain.

OBJECTIVE: To examine sex differences in lumbopelvic motion and symptom behavior during hip medial rotation in people with low back pain (LBP). We hypothesized that men would demonstrate greater and earlier lumbopelvic motion and would be more likely to report increased symptoms compared with women. DESIGN: Cross-sectional observational study. SETTING: University musculoskeletal analysis laboratory. PARTICIPANTS: Persons with chronic LBP (N=59; 30 men, 29 women) were recruited from the community and a university-based physical therapy clinic. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Lumbopelvic rotation range of motion, amount of hip rotation completed before the start of lumbopelvic motion, and provocation of LBP symptoms during the test of prone hip medial rotation were measured. RESULTS: Men demonstrated significantly more lumbopelvic rotation (men, 10.0°±5.1°; women, 4.5°±3.9°; P<.001) and completed less hip rotation before the start of lumbopelvic motion (men, 5.4°±3.8°; women, 16.0°±13.2°; P<.001) compared with women. Additionally, a significantly greater percentage of men (60.0%) than women (34.5%; P=.050) reported increased symptoms with hip medial rotation. CONCLUSIONS: Men could be at greater risk than women for experiencing LBP symptoms related to hip medial rotation as a result of greater and earlier lumbopelvic motion.

Low interrater reliability of examiners performing the prone instability test: a clinical test for lumbar shear instability.

OBJECTIVE: To test the interrater reliability of examiners performing the prone instability test (PIT), a clinical test proposed to identify lumbar shear instability. DESIGN: Cross-sectional test-retest design examining individuals with mechanical low back pain (LBP). SETTING: University-based musculoskeletal analysis laboratory. PARTICIPANTS: Individuals (N=30) with mechanical LBP recruited from community sources in a metropolitan region. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Repeated measures of a clinical examination test proposed to identify lumbar shear instability. RESULTS: Interrater reliability of examiners' judgments of PIT results were indexed with percentage of agreement and κ statistic. Examiners obtained 63% agreement and κ of .10 (95% confidence interval, -.27 to .47). Adjusted κ values based on prevalence and bias indexes were calculated to evaluate the effect on κ. The prevalence index associated with examiner judgments of the PIT was .43, and bias index was .03. The prevalence-adjusted bias-adjusted κ value was slightly higher than the unadjusted κ value (κ=.27; 95% confidence interval, -.08 to .61). CONCLUSIONS: Results of our study are not consistent with those of previous studies examining the reliability of therapists performing the PIT. We conclude that examiners do not attain acceptable interrater reliability when performing procedures for the PIT based on the information currently provided in the literature. Based on our experience, we suggest further exploration, standardization, and clarification of procedural details to improve therapists' ability to conduct the PIT on individuals with LBP.

Effect of classification-specific treatment on lumbopelvic motion during hip rotation in people with low back pain.

Increased and early lumbopelvic motion during trunk and limb movements is thought to contribute to low back pain (LBP). Therefore, reducing lumbopelvic motion could be an important component of physical therapy treatment. Our purpose was to examine the effects of classification-specific physical therapy treatment (Specific) based on the Movement System Impairment (MSI) model and non-specific treatment (Non-Specific) on lumbopelvic movement patterns during hip rotation in people with chronic LBP. We hypothesized that following treatment people in the Specific group would display decreased lumbopelvic rotation and achieve more hip rotation before lumbopelvic rotation began. We hypothesized that people in the Non-Specific group would display no change in these variables. Kinematic data collected before and after treatment for hip lateral and medial rotation in prone were analyzed. The Specific group (N = 16) demonstrated significantly decreased lumbopelvic rotation and achieved greater hip rotation before the onset of lumbopelvic rotation after treatment with both hip lateral and medial rotation. The Non-Specific group (N = 16) demonstrated significantly increased lumbopelvic rotation and no change in hip rotation achieved before the onset of lumbopelvic rotation. People who received treatment specific to their MSI LBP classification displayed decreased and later lumbopelvic motion with hip rotation, whereas people who received generalized non-specific treatment did not.

Differences in activity limitation between 2 low back pain subgroups based on the movement system impairment model.

OBJECTIVE: To examine if activity limitation differs between 2 low back pain (LBP) subgroups in the Movement System Impairment (MSI) model. DESIGN: Cross-sectional observational study. SETTING: University medical center musculoskeletal analysis laboratory. PARTICIPANTS: Convenience sample of 83 subjects with chronic LBP who were subgrouped as rotation (Rot) or rotation with extension (RotExt) according to the MSI model. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASUREMENTS: Subjects completed the modified Oswestry Low Back Pain Disability Questionnaire and the physical function subscale of the 36-Item Short-Form Health survey (SF-36 PFS) to assess activity limitation. Subjects also completed baseline measures related to demographics, LBP history, pain intensity, habitual activity level, general health status, and fear-avoidance behavior. Independent-samples t-tests, χ² tests of independence, and 2-way analysis of variance tests were used to analyze the data. RESULTS: Subjects in the Rot subgroup reported greater activity limitation on the modified Oswestry Questionnaire (P = .02) and SF-36 PFS (P = .03) than subjects in the RotExt subgroup. No other differences between LBP subgroups were significant (P > .05), except gender. More women (71%) than men (29%) were in the RotExt subgroup (P = .03). However, there was no main effect of gender and no interaction effect of gender and LBP subgroup on the modified Oswestry Questionnaire or the SF-36 PFS (P > .05). CONCLUSIONS: These results support that the Rot and RotExt LBP subgroups based on the MSI model differ with regard to variables that index activity limitation, with the Rot subgroup reporting greater limitation on both activity limitation measures. These differences are not the result of differences in other baseline measures.

Effect of metatarsal phalangeal joint extension on plantar soft tissue stiffness and thickness.

BACKGROUND: Plantar soft tissue stiffness and thickness are important biomechanical variables to understand stress concentrations that may contribute to tissue injury. OBJECTIVE: The purpose of this study was to determine the effects of passive metatarsal phalangeal joint (MPJ) extension on plantar soft tissue stiffness and thickness. METHODS: Seventeen healthy participants (7 male, 10 female, mean age 25.3 years, S.D. 4.4 years, mean BMI 24.7 kg/m(2), S.D. 3.2 kg/m(2)) were tested. Plantar soft tissue stiffness and thickness were measured at the metatarsal heads, midfoot and heel using a custom-built indentor device and an ultrasound machine. RESULTS: Indicators of soft tissue stiffness (K1 values) at the metatarsal heads and midfoot showed increases in stiffness of 81-88% (S.D.20-33%) in the MPJ extension position compared with the MPJ neutral position. Soft tissue thickness measures at the metatarsal heads with the MPJ in neutral ranged from a mean of 8.9 to 13.5mm and decreased, on average, by 8.8% (S.D. 2.9%) with MPJ extension. CONCLUSIONS: MPJ extension has a profound effect on increasing forefoot plantar soft tissue stiffness and a consistent but minimal effect on reducing soft tissue thickness. These changes may help transform the foot into a rigid lever at push-off consistent with the theory of the windlass mechanism.