Impact of deep brain stimulation on gait in Parkinson disease: A kinematic study

BACKGROUND

The effect of Deep Brain Stimulation (DBS) on gait in Parkinson's Disease (PD) is poorly understood. Kinematic studies utilizing quantitative gait outcomes such as speed, cadence, and stride length have shown mixed results and were done mostly before and after acute DBS discontinuation.

OBJECTIVE

To examine longitudinal changes in kinematic gait outcomes before and after DBS surgery.

METHOD

We retrospectively assessed changes in quantitative gait outcomes via motion capture in 22 PD patients before and after subthalamic (STN) or globus pallidus internus (GPi) DBS, in on medication state. Associations between gait outcomes and clinical variables were also assessed.

RESULT

Gait speed reduced from 110.7 ± 21.3 cm/s before surgery to 93.6 ± 24.9 after surgery (7.7 ± 2.9 months post-surgery, duration between assessments was 15.0 ± 3.8 months). Cadence, step length, stride length, and single support time reduced, while total support time, and initial double support time increased. Despite this, there was overall improvement in the Movement Disorder Society-Unified Parkinson Disease Rating Scale-Part III score "on medication/on stimulation" score (from 19.8 ± 10.7-13.9 ± 8.6). Change of gait speed was not related to changes in levodopa dosage, disease duration, unilateral vs bilateral stimulation, or target nucleus.

CONCLUSION

Quantitative gait outcomes in on medication state worsened after chronic DBS therapy despite improvement in other clinical outcomes. Whether these changes reflect the effects of DBS as opposed to ongoing disease progression is unknown.

Concurrent Validity of The Expanded Cutting Alignment Scoring Tool (E-CAST)

Background

The Expanded Cutting Alignment Scoring Tool (E-CAST) has been previously shown to be reliable when assessing lower extremity alignment during a 45-degree sidestep cut, however, the validity of this tool remains unknown. The purpose of this study was to assess the concurrent validity of the E-CAST by comparing visually identified movement errors from two-dimensional (2D) video with three-dimensional (3D) biomechanical variables collected using motion capture.

Study Design

Cross Sectional.

Methods

Sixty female athletes (age 14.1 ± 1.5 years) who regularly participated in cutting/pivoting sports performed a sidestep cut with 2D video and 3D motion capture simultaneously recording. One clinician scored the 2D videos for each limb using the E-CAST criteria. Joint angles and moments captured in 3D were computed for the trunk and knee. Receiver operating characteristic (ROC) curve analyses were performed to determine the accuracy of each E-CAST item and to provide cut-off points for risk factor identification.

Results

ROC analyses identified a cut-off point for all biomechanical variables with sensitivity and specificity ranging from 70-85% and 55-89%, respectively. Across items, the area under the curve ranged from 0.67 to 0.91.

Conclusion

The E-CAST performed with acceptable to outstanding area under the curve values for all variables except static knee valgus.

Level of evidence

3b.

Evaluation of Technical Performance of Ultrasound-Guided Procedures through Hand Motion Analysis: an Exploration of Motion Metrics

PURPOSE

To evaluate the ability of hand motion analysis using conventional and new motion metrics to differentiate between operators of varying levels of experience for central venous access (CVA) and liver biopsy (LB).

METHODS

CVA task: 7 Interventional Radiologists (experts), 10 senior trainees, and 5 junior trainees performed ultrasound-guided CVA on a standardized manikin; 5 trainees were retested after one year. LB task: 4 Radiologists (experts) and 7 trainees biopsied a lesion on a manikin. Conventional motion metrics (path length and task time), a refined metric (translational movements), and new metrics (rotational sum, rotational movements), were calculated.

RESULTS

CVA: experts outperformed trainees on all metrics (p ≤ 0.02). Senior trainees required fewer rotational movements (p = 0.02), translational movements (p = 0.045), and time (p = 0.001) than junior trainees. Similarly, on one-year follow-up, trainees had fewer translational (p=0.02) and rotational movements (p=0.003) with less task time (p=0.003). Path length and rotational sum were not different between junior and senior trainees or for trainees on follow-up. Rotational and translational movement had a greater area-under-the-curve (0.91 and 0.86 respectively) compared to rotational sum (0.73) and path length (0.61). LB: experts performed the task with a shorter path length (p=0.04), fewer translational movements (p=0.04), rotational movements (p=0.02), and less time (p<0.001) relative to the trainees.

CONCLUSION

Hand motion analysis using translational and rotational movements was better at differentiating levels of experience and improvement with training, as compared to the conventional metric of path length.

Ligand Dilution Analysis Facilitates Aptamer Binding Characterization at the Single-Molecule Level

Cell-specific aptamers offer a powerful tool to study membrane receptors at the single-molecule level. Most target receptors of aptamers are highly expressed on the cell surface, but difficult to analyze in situ because of dense distribution and fast velocity. Therefore, we herein propose a random sampling-based analysis strategy termed ligand dilution analysis (LDA) for easily implemented aptamer-based receptor study. Receptor density on the cell surface can be calculated based on a regression model. By using a synergistic ligand dilution design, colocalization and differentiation of aptamer and monoclonal antibody (mAb) binding on a single receptor can be realized. Once this is accomplished, precise binding site and detailed aptamer-receptor binding mode can be further determined using molecular docking and molecular dynamics simulation. The ligand dilution strategy also sets the stage for an aptamer-based dynamics analysis of two- and three-dimensional motion and fluctuation of highly expressed receptors on the live cell membrane.

Using 3-Dimensional Motion Analysis to Optimize Treatment Planning for a Patient With Dropfoot: Case Report

OBJECTIVE

This study demonstrated the use of computerized motion analysis to assist in evidence-based clinical decision-making.

CASE DESCRIPTION

A 15-year-old girl who had right hemiparesis after a stroke was referred for 3-dimensional computerized motion analysis to determine the effect of 3 devices intended to control her dropfoot and to assist in developing a treatment plan. Four conditions were tested and compared: barefoot, lateral support ankle brace, functional electrical stimulation (FES) device, and dropfoot cuff.

RESULTS

Kinematics showed the right ankle had significant dropfoot during swing phase (32.7 degrees of plantarflexion at terminal swing) in barefoot. The lateral support ankle brace, FES device, and dropfoot cuff reduced terminal swing plantarflexion to 27.2 degrees, 17.6 degrees, and 15.3 degrees, respectively, though ankle kinematics remained abnormal because of inadequate dorsiflexion. Improvements in gait variable score with FES (-8.2 degrees) or dropfoot cuff (-8.7 degrees) were significantly more than that with the lateral support brace (-2.2 degrees), and the difference in gait variable score between FES and dropfoot cuff was insignificant. Compared with the barefoot condition, the lateral support brace condition did not show a clinically significant difference in gait profile score; however, the gait profile scores of both FES and dropfoot cuff conditions showed clinically significant improvement (-1.7 degrees and -2.1 degrees, respectively).

CONCLUSION

Objective data delineated subtle changes among 3 devices and led to the recommendation to discontinue the lateral support ankle brace, continue using her night ankle-foot orthosis and FES device, with the dropfoot cuff as a backup when she feels leg fatigue or skin irritation, and consider serial casting or surgical calf lengthening.

IMPACT

Computerized motion analysis provides quantitative evaluation of subtle differences in the effect of braces with different designs, which are hard for the human eye to discern. The objective data inform and validate treatment decision-making. The recommendations were made as a result of evidence-based practice.

Measurement Performance of a Computer Assisted Vertebral Motion Analysis System

BACKGROUND

Segmental instability of the lumbar spine is a significant cost within the US health care system; however current thresholds for indication of radiographic instability are not well defined.

PURPOSE

To determine the performance measurements of sagittal lumbar intervertebral measurements using computerassisted measurements of the lumbar spine using motion sequences from a video-fluoroscopic technique.

STUDY DESIGN

Sensitivity, specificity, predictive values, prevalence, and test-retest reliability evaluation of digitized manual versus computer-assisted measurements of the lumbar spine.

PATIENT SAMPLE

A total of 2239 intervertebral levels from 509 symptomatic patients, and 287 intervertebral levels from 73 asymptomatic participants were retrospectively evaluated.

OUTCOME MEASURES

Specificity, sensitivity, negative predictive value (NPV), diagnostic accuracy, and prevalence between the two measurement techniques; Measurements of Coefficient of repeatability (CR), limits of agreement (LOA), intraclass correlation coefficient (ICC; type 3,1), and standard error of measurement for both measurement techniques.

METHODS

Asymptomatic individuals and symptomatic patients were all evaluated using both the Vertebral Motion Analysis (VMA) system and fluoroscopic flexion extension static radiographs (FE). The analysis was compared to known thresholds of 15% intervertebral translation (IVT, equivalent to 5.3mm assuming a 35mm vertebral body depth) and 25° intervertebral rotation (IVR).

RESULTS

The VMA measurements demonstrated greater specificity, % change in sensitivity, NPV, prevalence, and reliability compared with FE for radiographic evidence of instability. Specificity was 99.4% and 99.1% in the VMA compared to 98.3% and 98.2% in the FE for IVR and IVT, respectively. Sensitivity in this study was 41.2% and 44.6% greater in the VMA compared to the FE for IVR and IVT, respectively. NPV was 91% and 88% in the VMA compared to 62% and 66% in the FE for IVR and IVT, respectively. Prevalence was 12.3% and 11.9% for the VMA compared to 6.1% and 5.4% for the FE in IVR and IVT, respectively. Intra-observer IVR and IVT had a CR of 2.49 and 2.62, respectively. Inter-observer IVR and IVT had a CR of 1.99 and 2.81, respectively. Intra-subject (test/retest) CR were 2.49 and 3.11 for IVR and IVT, respectively.

CONCLUSIONS

The VMA system showed greater measurement performance in the detection of radiographic instability compared with FE radiographs.

Physical Activity during a Prolonged Congested Period in a Top-Class European Football Team

Purpose

The aim of the present study was to examine the variation in physical activity of elite soccer players within successive prolonged periods of fixture congestion over 5 months of competition during the competitive season 2011-2012.

Methods

Sixteen international players, classified into 6 positions (central defenders: CD; full-backs: FB; central defensive midfielders: CDM; wide midfielders: WM; central attacking midfielders: CAM; forwards: FW), were examined during the French First League, French Cup, and UEFA Champion's League matches. The total distance covered at light (<12 km.h⁻¹), sustained-cruising (>18-21 km.h⁻¹), high (>21-23 km.h⁻¹), very high (>23-25 km.h⁻¹), sub-maximal (>25-27 km.h⁻¹), and maximal (>27 km.h⁻¹) intensity running (IR) were measured and analysed using a semi-automatic match analysis system (Amisco Pro™).

Results

No differences were observed between congested and non-congested periods (two vs. one match a week, respectively) for the total distance covered at all the speed thresholds over 18 km.h⁻¹, with no variation in physical fitness over the 5 studied months. Specifically to the playing positions, regardless of the congestion periods, FB and WM covered more distance than CDM over 21km.h⁻¹; FB, WM and FW covered similar distances for all running intensities; and CD and CDM covered shorter distance during non-congested compared to congested periods (P<0.05) at light-IR.

Conclusion

The present study reveals that prolonged congested match fixture did not affect the high-intensity physical activity of top-class soccer players during official games during a 5 months fixture period.

Segmental motion of forefoot and hindfoot as a diagnostic tool

Segmental motions derived from non-invasive motion analysis are being used to investigate the intrinsic functional behavior of the foot and ankle in health and disease. The goal of this research was to examine the ability of a generic segmented model of the foot to capture and differentiate changes in internal skeletal kinematics due to neuromuscular disease and/or trauma. A robotic apparatus that reproduces the kinematics and kinetics of gait in cadaver lower extremities was employed to produce motion under normal and aberrant neuromuscular activation patterns of tibialis posterior and/or tibialis anterior. Stance phase simulations were conducted on 10 donor limbs while recording three-dimensional kinematic trajectories of (1) skin-mounted markers used clinically to construct segmented foot models, and (2) bone-mounted marker clusters to capture actual internal bone motion as the gold standard for comparison. The models constructed from external marker data were able to differentiate the kinematic behaviors elicited by different neuromuscular conditions in a manner similar to that using the bone-derived data. Measurable differences between internal and externally measured kinematics were small, variable and random across the three axes of rotation and neuromuscular conditions, with a tendency toward more differences noted during early and late stance. Albeit slightly different, three-dimensional motion profiles of the hindfoot and forefoot segments correlated well with internal skeletal motion under all neuromuscular conditions, thereby confirming the utility of measuring segmental motions as a valid means of clinical assessment.