Publications

M Yamagami, KM Peters, I Milovanovic, I Kuang, Z Yang, N Lu, KM Steele (2018) “Assessment of Dry Epidermal Electrodes for Long-Term Electromyography Measurements.” Sensors

Keshia JournalArticle, Projects, Publications, UbiquitousRehabilitation
Sample sEMG signal from one subject’s FCU for (left) MVIC; (middle) dynamic and (right) functional tests indicate that there were no significant differences between the Delsys (lighter grey) and ESS electrodes (darker grey) based on raw sEMG amplitude, linear envelope amplitude, or power spectral density.

Journal article in Sensors:

In collaboration with University of Texas – Austin, we evaluated a new flexible, gold-based epidermal electrode for sensing muscle activity.

Sample sEMG signal from one subject’s FCU for (left) MVIC; (middle) dynamic and (right) functional tests indicate that there were no significant differences between the Delsys (lighter grey) and ESS electrodes (darker grey) based on raw sEMG amplitude, linear envelope amplitude, or power spectral density.Background: Commercially available electrodes can only provide quality surface electromyography (sEMG) measurements for a limited duration due to user discomfort and signal degradation, but in many applications, collecting sEMG data for a full day or longer is desirable to enhance clinical care. Few studies for long-term sEMG have assessed signal quality of electrodes using clinically relevant tests. The goal of this research was to evaluate flexible, gold-based epidermal sensor system (ESS) electrodes for long-term sEMG recordings.

Methods: We collected sEMG and impedance data from eight subjects from ESS and standard clinical electrodes on upper extremity muscles during maximum voluntary isometric contraction tests, dynamic range of motion tests, the Jebsen Taylor Hand Function Test, and the Box & Block Test. Four additional subjects were recruited to test the stability of ESS signals over four days.

Results: Signals from the ESS and traditional electrodes were strongly correlated across tasks. Measures of signal quality, such as signal-to-noise ratio and signal-to-motion ratio, were also similar for both electrodes.

Conclusions: Over the four-day trial, no significant decrease in signal quality was observed in the ESS electrodes, suggesting that thin, flexible electrodes may provide a robust tool that does not inhibit movement or irritate the skin for long-term measurements of muscle activity in rehabilitation and other applications.

Brianna Goodwin Presents at Seattle Children’s Grand Rounds

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Brianna Goodwin, a Master’s student in our lab, presented her collaborative Brianna Goodwin is pictured behind a podium, standing in front of her slideshow during her presentation.abstract on monitoring Constraint-Induced Movement Therapy (CIMT), a therapy for children with hemiplegic cerebral palsy (CP), at the Seattle Children’s Hospital (SCH) Grand Rounds this past week. The Grand Rounds are a time to present research, new ideas, and translational science to medical personnel of varied background.

To read Brianna’s abstract in full, download her PDF here: SCH Grand Rounds, CIMT abstract

 

AA Portnova, G Mukherjee, KM Peters, A Yamane, KM Steele (2018) “Design of a 3D-printed, open-source wrist-driven orthosis for individuals with spinal cord injury.” PLOSOne

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Journal article in PLOSOne: In collaboration with the University of Washington Prosthetics and Orthotics Division, a user-centered design approach was used to improve the design and wearability of a passive, wrist-driven orthosis. To read the article in full, click HERE. To access the open-source print files, click HERE.

Orthotists in training assemble the 3D-printed parts of a new wrist-driven orthosis in the top image. The lower image showcases a user gripping a pen in his freshly donned orthosis.Background: Assistive technology, such as wrist-driven orthoses (WDOs), can be used by individuals with spinal cord injury to improve hand function. A lack of innovation and challenges in obtaining WDOs have limited their use. These orthoses can be heavy and uncomfortable for users and also time-consuming for orthotists to fabricate.

Purpose/Methods: The goal of this research was to design a WDO with user (N = 3) and orthotist (N = 6) feedback to improve the accessibility, customizability, and function of WDOs by harnessing advancements in 3D-printing.

Results: The 3D-printed WDO reduced hands-on assembly time to approximately 1.5 hours and the material costs to $15 compared to current fabrication methods. Varying improvements in users’ hand function were observed during functional tests, such as the Jebsen Taylor Hand Function Test. For example, one participant’s ability on the small object task improved by 29 seconds with the WDO, while another participant took 25 seconds longer to complete this task with the WDO. Two users had a significant increase in grasp strength with the WDO (13–122% increase), while the other participant was able to perform a pinching grasp for the first time.

The WDO designs are available open-source to increase accessibility and encourage future innovation.

M Goudriaan, BR Shuman, KM Steele, M Van den Hauwe, N Goemans, G Molenaers, K Desloovere (2018) “Non-neural Muscle Weakness Has Limited Influence on Complexity of Motor Control during Gait.” Frontiers in Human Neuroscience

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Journal Article in Frontiers in Human Neuroscience:

Despite significant differences in kinematics children with Duchenne muscular dystrophy have similar control complexity to typically developing children.

Abstract: Cerebral palsy (CP) and Duchenne muscular dystrophy (DMD) are neuromuscular disorders characterized by muscle weakness. Weakness in CP has neural and non-neural components, whereas in DMD, weakness can be considered as a predominantly non-neural problem. Despite the different underlying causes, weakness is a constraint for the central nervous system when controlling gait. CP demonstrates decreased complexity of motor control during gait from muscle synergy analysis, which is reflected by a higher total variance accounted for by one synergy (tVAF1). However, it remains unclear if weakness directly contributes to higher tVAF1 in CP, or whether altered tVAF1 reflects mainly neural impairments. If muscle weakness directly contributes to higher tVAF1, then tVAF1 should also be increased in DMD. To examine the etiology of increased tVAF1, muscle activity data of gluteus medius, rectus femoris, medial hamstrings, medial gastrocnemius, and tibialis anterior were measured at self-selected walking speed, and strength data from knee extensors, knee flexors, dorsiflexors and plantar flexors, were analyzed in 15 children with CP [median (IQR) age: 8.9 (2.2)], 15 boys with DMD [8.7 (3.1)], and 15 typical developing (TD) children [8.6 (2.7)]. We computed tVAF1 from 10 concatenated steps with non-negative matrix factorization, and compared tVAF1between the three groups with a Mann-Whiney U-test. Spearman’s rank correlation coefficients were used to determine if weakness in specific muscle groups contributed to altered tVAF1. No significant differences in tVAF1 were found between DMD [tVAF1: 0.60 (0.07)] and TD children [0.65 (0.07)], while tVAF1 was significantly higher in CP [(0.74 (0.09)] than in the other groups (both p < 0.005). In CP, weakness in the plantar flexors was related to higher tVAF1 (r = −0.72). In DMD, knee extensor weakness related to increased tVAF1 (r = −0.50). These results suggest that the non-neural weakness in DMD had limited influence on complexity of motor control during gait and that the higher tVAF1 in children with CP is mainly related to neural impairments caused by the brain lesion.

KM Peters, VE Kelly, T Chang, MC Weismann, S Westcott McCoy, KM Steele (2018) “Muscle recruitment and coordination during upper-extremity functional tests.” Journal of Electromyography and Kinesiology

Keshia JournalArticle, Publications ,

Journal article in Journal of Electromyography and Kinesiology:

In collaboration with Rehabilitation Medicine here at the University of Washington, we evaluated muscle use of 20 unimpaired participants during three upper-extremity functional tests. An interactive supplement can be found HERE.

Recruitment and cocontration plots of eight upper-extremity muscles during the Jebsen Taylor Hand Function Test.Background: Performance-based tests, such as the Jebsen Taylor Hand Function Test or Chedoke Arm and Hand Activity Inventory, are commonly used to assess functional performance after neurologic injury. However, the muscle activity required to execute these tasks is not well understood, even for unimpaired individuals. The purpose of this study was to evaluate unimpaired muscle recruitment and coordination of the dominant and non-dominant limbs during common clinical tests.

Methods: Electromyography (EMG) recordings from eight arm muscles were monitored bilaterally for twenty unimpaired participants while completing these tests. Average signal magnitudes, activation times, and cocontraction levels were calculated from the filtered EMG data, normalized by maximum voluntary isometric contractions (MVICs).

Results: Overall, performance of these functional tests required low levels of muscle activity, with average EMG magnitudes less than 6.5% MVIC for all tests and muscles, except the extensor digitorum, which had higher activations across all tasks (11.7 ± 2.7% MVIC, dominant arm). When averaged across participants, cocontraction was between 25 and 62% for all tests and muscle pairs.

Conclusion: Tasks evaluated by speed of completion, rather than functional quality of movement demonstrated higher levels of muscle recruitment. These results provide baseline measurements that can be used to evaluate muscle-specific deficits after neurologic injury and track recovery using common clinical tests.