Reachable workspace and performance of upper limb (PUL) in duchenne muscular dystrophy

Introduction: The Kinect‐based reachable workspace relative surface area (RSA) is compared with the performance of upper limb (PUL) assessment in Duchenne muscular dystrophy (DMD). Methods: 29 individuals with DMD (ages: 7–23; Brooke: 1–5) underwent both Kinect‐based reachable workspace RSA and PUL assessments. RSAs were also collected from 24 age‐matched controls. Total and quadrant RSAs were compared with the PUL total, shoulder‐, middle‐, and distal‐dimension scores. Results: The total reachable workspace RSA correlated well with the total PUL score (Spearman ρ = ‐0.602; P < 0.001), and with each of the PUL dimensional scores: shoulder (ρ = ‐0.624; P < 0.001), middle (ρ = ‐0.564; P = 0.001), and distal (ρ = ‐0.630; P < 0.001). With quadrant RSA, reachability in a particular quadrant was closely associated with respective PUL dimensional‐level function (lateral‐upper quadrant for shoulder‐, lateral‐upper/lower quadrants for middle‐, and lateral‐lower quadrant for distal‐level function). Conclusions: This study demonstrates concurrent validity of the reachable workspace outcome measure (RSA) with the DMD‐specific upper extremity outcome measure (PUL). Muscle Nerve 53: 545–554, 2016     

Reachable workspace in facioscapulohumeral muscular dystrophy (FSHD) by kinect

Introduction: A depth‐ranging sensor (Kinect) based upper extremity motion analysis system was applied to determine the spectrum of reachable workspace encountered in facioscapulohumeral muscular dystrophy (FSHD). Methods: Reachable workspaces were obtained from 22 individuals with FSHD and 24 age‐ and height‐matched healthy controls. To allow comparison, total and quadrant reachable workspace relative surface areas (RSAs) were obtained by normalizing the acquired reachable workspace by each individual's arm length. Results: Significantly contracted reachable workspace and reduced RSAs were noted for the FSHD cohort compared with controls (0.473 ± 0.188 vs. 0.747 ± 0.082; P < 0.0001). With worsening upper extremity function as categorized by the FSHD evaluation subscale II + III, the upper quadrant RSAs decreased progressively, while the lower quadrant RSAs were relatively preserved. There were no side‐to‐side differences in reachable workspace based on hand‐dominance. Conclusions: This study demonstrates the feasibility and potential of using an innovative Kinect‐based reachable workspace outcome measure in FSHD. Muscle Nerve 51 : 168–175, 2015     

Upper extremity 3‐dimensional reachable workspace assessment in amyotrophic lateral sclerosis by Kinect sensor

Introduction: Reachable workspace is a measure that provides clinically meaningful information regarding arm function. In this study, a Kinect sensor was used to determine the spectrum of 3‐dimensional reachable workspace encountered in a cross‐sectional cohort of individuals with amyotrophic lateral sclerosis (ALS). Methods: Bilateral 3D reachable workspace was recorded from 10 subjects with ALS and 17 healthy controls. The data were normalized by each individual's arm length to obtain a reachable workspace relative surface area (RSA). Concurrent validity was assessed by correlation with scoring on the ALS Functional Rating Score—revised (ALSFRSr). Results: The Kinect‐measured reachable workspace RSA differed significantly between the ALS and control subjects (0.579 ± 0.226 vs. 0.786 ± 0.069; P < 0.001). The RSA demonstrated correlation with ALSFRSr upper extremity items (Spearman correlation ρ = 0.569; P = 0.009). With worsening upper extremity function, as categorized by the ALSFRSr, the reachable workspace also decreased progressively. Conclusions: This study demonstrates the feasibility and potential of using a novel Kinect‐based reachable workspace outcome measure in ALS. Muscle Nerve 53: 234–241, 2016     

Longitudinal study of upper extremity reachable workspace in fascioscapulohumeral muscular dystrophy

Facioscapulohumeral Dystrophy (FSHD) results in slowly progressive strength impairment, especially the upper extremities. Recent discoveries regarding pathophysiology have led to exciting novel therapeutic strategies. To further facilitate drug development, improved FSHD outcome measures that are functionally-relevant and sensitive to longitudinal change will be critical. Recently, a motion sensor (Kinect)-based upper extremity outcome called ‘reachable workspace’ that provides a quantitative reconstruction of an individual's reachability was developed. In this study, changes in reachable workspace were tracked upwards for five-years in 18 FSHD subjects. Results show -1.63 %/year decline in total reachable workspace (p = 0.144); with most notable decline in the above-the-shoulder level quadrants (upper-lateral Q3: -9.5 %/year, p < 0.001 and upper-medial Q1: -6.8 %/ year, p = 0.063) with no significant changes in the lower quadrants (Q2, Q4). Reachable workspace declined more significantly if the subjects were challenged with 500 g wrist weights: total reachable workspace: -1.82 %/year, p = 0.039; Q1: -7.20 %/year, p = 0.041; Q3: -8.09 %/year, p = 0.001. Importantly, reachable workspace outcome was also able to distinguish subgroups in FSHD: mildly- and severely-affected with essentially unchanging reachability over years, and moderately-affected who demonstrate the most detectable changes longitudinally. The study demonstrates utility for measuring declines in upper quadrant reachability, and provides enrichment/stratification of FSHD populations most likely to show treatment effects in clinical trials.     

Upper extremity 3‐dimensional reachable workspace analysis in dystrophinopathy using Kinect

Introduction: An innovative upper extremity 3‐dimensional (3D) reachable workspace outcome measure acquired using the Kinect sensor is applied toward Duchenne/Becker muscular dystrophy (DMD/BMD). The validity, sensitivity, and clinical meaningfulness of this novel outcome measure are examined. Methods: Upper extremity function assessment (Brooke scale and NeuroQOL questionnaire) and Kinect‐based reachable workspace analyses were conducted in 43 individuals with dystrophinopathy (30 DMD and 13 BMD, aged 7–60 years) and 46 controls (aged 6–68 years). Results: The reachable workspace measure reliably captured a wide range of upper extremity impairments encountered in both pediatric and adult, as well as ambulatory and non‐ambulatory individuals with dystrophinopathy. Reduced reachable workspaces were noted for the dystrophinopathy cohort compared with controls, and they correlated with Brooke grades. In addition, progressive reduction in reachable workspace correlated directly with worsening ability to perform activities of daily living, as self‐reported on the NeuroQOL. Conclusion: This study demonstrates the utility and potential of the novel sensor‐acquired reachable workspace outcome measure in dystrophinopathy. Muscle Nerve 52:344–355, 2015     

Grip strength is a representative measure of muscle weakness in the upper extremity after stroke

Background: Muscle weakness is the most common impairment in the upper extremity after stroke, leading to a reduced ability to use the arm and the hand in daily activities. Grip strength is easier to measure than precise, but more time-consuming, isokinetic and isometric arm muscle strength measurements. It would therefore be advantageous in a clinical setting if grip strength could be used as a proxy for muscle strength in the entire upper extremity.

Objective: To investigate the association between grip strength and isometric and isokinetic arm muscle strength in persons with chronic stroke.

Methods: Forty-five persons with mild-to-moderate paresis in the upper extremity, at least 6 months post-stroke participated. Isometric grip strength was measured with a computerized grip dynamometer and arm strength (isometric shoulder abduction and elbow flexion as well as isokinetic elbow extension and flexion) with an isokinetic dynamometer. Pearson’s correlation coefficient was used to determine the association between the muscle strength measurements.

Results: There were significant correlations (p < .0001) between grip strength and all arm strength measurements in both the more affected (r = 0.77–0.82) and the less affected upper extremity (r = 0.65–0.82).

Conclusion: This cross-sectional study showed that grip strength is strongly associated with muscle strength in the arm in persons in the chronic phase after stroke. As grip strength is easy to measure and less time-consuming than arm muscle strength measurements, this implies that grip strength can be a representative measure of muscle weakness of the entire upper extremity in the chronic phase after stroke.     

Restrictive lung involvement in facioscapulohumeral muscular dystrophy

Introduction: Few studies have evaluated the frequency or predisposing factors for respiratory involvement in facioscapulohumeral muscular dystrophy type 1 (FSHD1) and type 2 (FSHD2). Methods: We performed a prospective cross‐sectional observational study of 61 genetically confirmed FSHD participants (53 FSHD1 and 8 FSHD2). Participants underwent bedside pulmonary function testing in sitting and supine positions, a standard clinical history and physical assessment, and manual muscle testing. Results: Restrictive respiratory involvement was suggested in 9.8% (95% confidence interval 2.4–17.3): 7.5% FSHD1 and 25.0% FSHD2 (P = 0.17). Participants with testing suggestive of restrictive lung involvement (n = 6) were more severely affected (P = 0.005), had weaker hip flexion (P = 0.0007), and were more likely to use a wheelchair (P = 0.01). Conclusions: Restrictive respiratory involvement should be considered in all moderate to severely affected FSHD patients with proximal lower extremity weakness. The higher frequency of restrictive lung disease in FSHD2 seen here requires confirmation in a larger cohort of FSHD2 patients. Muscle Nerve 50 : 739–743, 2014     

Effects of body orientation on maximum voluntary arm torques

Introduction: Increased reliance on bulbospinal motor systems has been implicated in individuals with chronic stroke during maximum voluntary arm joint torque generation. Methods: Maximum isometric single‐joint and multi‐joint arm strength was observed in two body orientations (sitting and supine) while maintaining identical head/neck/trunk/extremity joint configurations in order to identify bulbospinal contributions to maximum joint torque generation in 11 individuals with stroke and 10 individuals without stroke. Results: During sitting, shoulder flexion was greater for both groups, whereas shoulder extension and elbow flexion, part of the “flexion synergy,” were greater only in individuals with stroke. Conclusions: Body orientation influenced isometric arm strength, notably the constituents of flexion synergy in individuals with stroke, suggesting bulbospinal motor pathway involvement. From a practical perspective, clinical evaluation of single joint strength in the supine position may underestimate strength available during activities of daily living that are performed in an upright orientation. Muscle Nerve, 2011     

Upper extremity function and its relation with hand sensation and upper extremity strength in patients with multiple sclerosis

The purpose of this study was to investigate the relationships between the upper extremity functions, upper extremity strength and hand sensation in patients with Multiple Sclerosis (MS). Twenty-two patients with MS (mean age: 38.5 ± 8.31 years, median Expanded Disability Status Scale (EDSS): 2) and 10 healthy subjects were included. Upper extremity function was measured with the Nine-hole peg test, upper extremity strength (shoulder flexion-abduction, elbow flexion, pinch and grip) with hand-held dynamometer, hand grip dynamometer and manual pinch meter, threshold of light touch-pressure with Semmes-Weinstein monofilament, duration of vibration with 128-Hz frequency tuning fork, and distance of two-point discrimination with an aesthesiometer. Strength and functional level of the upper extremity, light touch-pressure, two-point discrimination, vibration sensations of the hand were lower in patients with MS compared with healthy controls (p < 0.05). Light touch-pressure sensation of thumb and index fingers, two-point discrimination of index finger and elbow flexion strength were found to be related with upper extremity function in patients with MS (p< 0.05). These results indicate that the hand sensation, upper extremity strength and function were affected in MS patients. Additionally upper extremity functions seem to be related with light touch-pressure and two-point discrimination sensations of the hand and elbow flexion strength. Upper extremity strengthening and sensorial training of the hand may contribute to the upper extremity function in patients with MS.     

Reorganization of flexion reflexes in the upper extremity of hemiparetic subjects.

We examined spatiotemporal abnormalities in the flexor reflex response in the impaired upper extremity of hemiparetic subjects. Electrical stimulation was used to elicit flexion reflexes in both upper extremities of 8 hemiparetic brain-injured and 6 control subjects. Electromyograms (EMGs) were recorded from 12 arm muscles, and reflex forces and moments were recorded at the wrist with a load cell, and converted to shoulder and elbow torques. We found that the onset of reflex torque and EMG was delayed in the impaired arm and delays were greater at the shoulder than at the elbow. The normal reflex torque response consisted of elbow flexion, shoulder extension, and shoulder adduction. In contrast, in the impaired limb shoulder, flexion torque was observed in 7 subjects and shoulder abduction in 3. The delays in reflex onset and altered torque patterns in the impaired arm may be related to the abnormal movement synergies observed following stroke. © 1999 John Wiley & Sons, Inc.     

Whole‐body magnetic resonance imaging evaluation of facioscapulohumeral muscular dystrophy

Introduction: Facioscapulohumeral muscular dystrophy (FSHD) is a hereditary disorder that causes progressive muscle wasting. Increasing knowledge of the pathophysiology of FSHD has stimulated interest in developing biomarkers of disease severity. Methods: Two groups of MRI scans were analyzed: whole‐body scans from 13 subjects with FSHD; and upper and lower extremity scans from 34 subjects with FSHD who participated in the MYO‐029 clinical trial. Muscles were scored for fat infiltration and edema‐like changes. Fat infiltration scores were compared with muscle strength and function. Results: The analysis revealed a distinctive pattern of both frequent muscle involvement and frequent sparing in FSHD. Averaged fat infiltration scores for muscle groups in the legs correlated with quantitative muscle strength and 10‐meter walk times. Conclusions: Advances in MRI technology allow for acquisition of rapid, high‐quality, whole‐body imaging in diffuse muscle disease. This technique offers a promising disease biomarker in FSHD and other muscle diseases. Muscle Nerve 52: 512–520, 2015     

Fatigue and recovery from dynamic contractions in men and women differ for arm and leg muscles

Introduction: Whether there is a gender difference in fatigue and recovery from maximal velocity fatiguing contractions and across muscles is not understood. Methods: Sixteen men and 19 women performed 90 isotonic contractions at maximal voluntary shortening velocity (maximal velocity concentric contractions, MVCC) with the elbow flexor and knee extensor muscles (separate days) at a load equivalent to 20% maximal voluntary isometric contraction (MVIC). Results: Power (from MVCCs) decreased similarly for men and women for both muscles (P > 0.05). Men and women had similar declines in MVIC of elbow flexors, but men had greater reductions in knee extensor MVIC force and MVIC electromyogram activity than women (P < 0.05). The decline in MVIC and power was greater, and force recovery was slower for the elbow flexors compared with knee extensors. Conclusions: The gender difference in muscle fatigue often observed during isometric tasks was diminished during fast dynamic contractions for upper and lower limb muscles. Muscle Nerve 48 : 436–439, 2013     

Resistance training and aerobic training improve muscle strength and aerobic capacity in chronic inflammatory demyelinating polyneuropathy

Introduction: We investigated the effects of aerobic and resistance exercise in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). Methods: Eighteen CIDP patients treated with subcutaneous immunoglobulin performed 12 weeks of aerobic exercise and 12 weeks of resistance exercise after a run‐in period of 12 weeks without exercise. Three times weekly the participants performed aerobic exercise on an ergometer bike or resistance exercise with unilateral training of knee and elbow flexion/extension. Primary outcomes were maximal oxygen consumption velocity (VO₂‐max) and maximal combined isokinetic muscle strength (cIKS) of knee and elbow flexion/extension. Results: VO₂‐max and muscle strength were unchanged during run‐in (?4.9% ± 10.3%, P = 0.80 and ?3.7% ± 10.1%, P = 0.17, respectively). Aerobic exercise increased VO₂‐max by 11.0% ± 14.7% (P = 0.02). Resistance exercise resulted in an increase of 13.8% ± 16.0% (P = 0.0004) in cIKS. Discussion: Aerobic exercise training and resistance exercise training improve fitness and strength in CIDP patients. Muscle Nerve 57 : 70–76, 2018     

Evaluation of admittance control as an alternative to passive arm supports to increase upper extremity function for individuals with Duchenne muscular dystrophy

The degree of upper extremity active range of motion provided by an admittance control robot compared with a commercially available passive arm support for individuals with DMD who have limited arm function was investigated in this study. The reachable workspace evaluation was used to assess active range of motion provided by both devices. A visual analog scale was also used to secure participant-reported outcome measures. The admittance control robot significantly increased reachable surface area scores compared with the passive arm support for the dominant arm (Wilcoxon T = 5, P = .022, r² = 0.263) and for the nondominant arm (paired-samples t test, t(9) = 4.66, P = .001, r² = 0.71). The admittance control robot also significantly decreased participant-reported exertion compared with the passive arm support. Results of this study substantiated the benefits of admittance control for individuals with DMD compared with a commercially available passive arm support.     

Shoulder strength profiles in children with and without brachial PLEXUS PALSY

Introduction: We characterized bilateral shoulder strength and the balance of antagonist/agonist muscle pairs in children with brachial plexus palsy (BPP) and with typical development (TD). Methods: In 15 children with unilateral BPP and 11 with TD, bilateral maximal isometric shoulder strength in flexion/extension, internal/external rotation, and abduction/adduction was recorded using a hand‐held dynamometer. Correlation between strength and active range of motion were evaluated using the Mallet score. Results: Children with BPP had strength asymmetry in all muscles, whereas children with TD had significant strength asymmetry for flexors and abductors. In children with BPP, extensors and external rotators were the weakest muscles, leading to sagittal and transverse plane muscle imbalances. Higher strength values were related to better active range of motion. Conclusions: This study highlights the importance of documenting shoulder strength profiles in children with BPP which may help predict deformity development. Muscle Nerve 50 : 60–66, 2014     

Muscle pathology grade for facioscapulohumeral muscular dystrophy biopsies

Introduction: As we move toward planning for clinical trials in facioscapulohumeral muscular dystrophy (FSHD), a better understanding of the clinical relationship with morphological changes in FSHD muscle biopsies will be important for stratifying patients and understanding post‐therapeutic changes in muscle. Methods: We performed a prospective cross‐sectional study of quadriceps muscle biopsies in 74 genetically confirmed FSHD participants (64 with FSHD type 1 and 10 with FSHD type 2). We compared a 12‐point muscle pathology grade to genetic mutation, disease severity score, and quantitative myometry. Results: Pathology grade had moderate correlations with genetic mutation (rho = –0.45, P < 0.001), clinical severity score (rho = 0.53, P < 0.001), disease duration (rho = 0.31, P = 0.03), and quantitative myometry (rho = –0.47, P < 0.001). We found no difference in the frequency of inflammation between FSHD types 1 and 2. Conclusions: The pathology grade of quadriceps muscle may be a useful marker of disease activity in FSHD, and it may have a role in stratification for future clinical trials. Muscle Nerve 52: 521–526, 2015     

Involuntary paretic wrist/finger flexion forces and EMG increase with shoulder abduction load in individuals with chronic stroke

ObjectiveClinical observations of the flexion synergy in individuals with chronic hemiparetic stroke describe coupling of shoulder, elbow, wrist, and finger joints. Yet, experimental quantification of the synergy within a shoulder abduction (SABD) loading paradigm has focused only on shoulder and elbow joints. The paretic wrist and fingers have typically been studied in isolation. Therefore, this study quantified involuntary behavior of paretic wrist and fingers during concurrent activation of shoulder and elbow.MethodsEight individuals with chronic moderate-to-severe hemiparesis and four controls participated. Isometric wrist/finger and thumb flexion forces and wrist/finger flexor and extensor electromyograms (EMG) were measured at two positions when lifting the arm: in front of the torso and at maximal reaching distance. The task was completed in the ACT^3D robotic device with six SABD loads by paretic, non-paretic, and control limbs.ResultsConsiderable forces and EMG were generated during lifting of the paretic arm only, and they progressively increased with SABD load. Additionally, the forces were greater at the maximal reach position than at the position front of the torso.ConclusionsFlexion of paretic wrist and fingers is involuntarily coupled with certain shoulder and elbow movements.SignificanceActivation of the proximal upper limb must be considered when seeking to understand, rehabilitate, or develop devices to assist the paretic hand.     

Validity of the 6 minute walk test in facioscapulohumeral muscular dystrophy

Introduction: In preparation for future clinical trials, we determined the reliability, relationship to measures of disease severity, and consistency across sites of the 6 Minute Walk Test (6MWT) in patients with facioscapulohumeral muscular dystrophy (FSHD). Methods: Genetically defined and clinically affected FSHD participants at 2 sites performed the 6MWT, the Timed Up and Go, and the 30 foot Go/Timed 10 meter test as measures of mobility using standard procedures. Results: Eight‐six participants representing the full range of severity performed the 6MWT. The mean 6MWT distance was 404.3 meters (SD 123.9), with no difference between sites. The 6MWT was reliable (n = 25; intraclass correlation coefficient = 0.99) and demonstrated moderate to strong correlations with lower extremity strength, functional outcomes, and FSHD Clinical Score. Conclusions: The 6MWT is reliable and is associated with other measures of FSHD disease severity. Future directions include assessing its sensitivity to disease progression. Muscle Nerve 55 : 333–337, 2017     

Evidence for strength imbalances as a significant contributor to abnormal synergies in hemiparetic subjects

Abnormal synergies in the paretic shoulder and elbow of hemiparetic subjects were quantified during maximal voluntary contractions (MVCs) in 27 subjects with a history of stroke and 8 age-matched control subjects. A six-axis load cell allowed simultaneous measurement of the primary torque the subject was attempting to maximize and the secondary torques at other joint actions. For example, during MVC of shoulder flexion, shoulder flexion is the primary torque and the secondary torques are internal/external rotation, abduction/adduction, and elbow flexion/extension. In general, the stroke subjects had increased secondary torques compared to controls, resulting in abnormal joint torque coupling within the set consisting of elbow flexion, internal rotation, adduction, shoulder flexion. Unlike previous studies, abnormal secondary torques in several cases were due to strength imbalances, which occur when the strength deficit for a particular joint action is greater than the strength deficit in the opposite joint action. This hypothesis was supported by electromyographic recordings and by the finding that subjects with larger strength imbalances tended to produce larger secondary torques. Possible mechanisms and consequences for rehabilitative treatments are discussed.     

From mental power to muscle power--gaining strength by using the mind

The purposes of this project were to determine mental training-induced strength gains (without performing physical exercises) in the little finger abductor as well as in the elbow flexor muscles, which are frequently used during daily living, and to quantify cortical signals that mediate maximal voluntary contractions (MVCs) of the two muscle groups. Thirty young, healthy volunteers participated in the study. The first group (N = 8) was trained to perform "mental contractions" of little finger abduction (ABD); the second group (N = 8) performed mental contractions of elbow (ELB) flexion; and the third group (N = 8) was not trained but participated in all measurements and served as a control group. Finally, six volunteers performed training of physical maximal finger abductions. Training lasted for 12 weeks (15 min per day, 5 days per week). At the end of training, we found that the ABD group had increased their finger abduction strength by 35% (P < 0.005) and the ELB group augmented their elbow flexion strength by 13.5% (P < 0.001). The physical training group increased the finger abduction strength by 53% (P < 0.01). The control group showed no significant changes in strength for either finger abduction or elbow flexion tasks. The improvement in muscle strength for trained groups was accompanied by significant increases in electroencephalogram-derived cortical potential, a measure previously shown to be directly related to control of voluntary muscle contractions. We conclude that the mental training employed by this study enhances the cortical output signal, which drives the muscles to a higher activation level and increases strength.