Relationship between function, strength and electromyography of upper extremities of persons with tetraplegia

Electromyography-Force Relation and Muscle Fiber Conduction Velocity Affected by Spinal Cord Injury

A surface electromyography (EMG) analysis was performed in this study to examine central neural and peripheral muscle changes after a spinal cord injury (SCI). A linear electrode array was used to record surface EMG signals from the biceps brachii (BB) in 15 SCI subjects and 14 matched healthy control subjects as they performed elbow flexor isometric contractions from 10% to 80% maximum voluntary contraction. Muscle fiber conduction velocity (MFCV) and BB EMG-force relation were examined. MFCV was found to be significantly slower in the SCI group than the control group, evident at all force levels. The BB EMG-force relation was well fit by quadratic functions in both groups. All healthy control EMG-force relations were best fit with positive quadratic coefficients. In contrast, the EMG-force relation in eight SCI subjects was best fit with negative quadratic coefficients, suggesting impaired EMG modulation at high forces. The alterations in MFCV and EMG-force relation after SCI suggest complex neuromuscular changes after SCI, including alterations in central neural drive and muscle properties.

[Predictors of upper limbs' function in patients with cervical tetraplegia]

Patients with traumatic cervical injury of the spinal cord show clinical symptoms of tetraplegia. Furthermore, the motor function of the upper limbs is a key function for such patients, because it has a significant impact on the quality of life. One of the components of the definition of rehabilitation potential is the identification of the possible functions' ceiling and compliance of the patient's current condition with known model characteristics.

OBJECTIVE

The aim of the study is to determine the predictors of upper limb functional motor activity in patients in the late period after spinal cord injury (SCI).

MATERIAL AND METHODS

The study included 190 patients with SCI: 151 men and 49 women. The mean age of patients was 30.0±12.9 years, the age of SCI - 1.9 [0.60; 5.40] years, in 93% of cases SCI was traumatic. Patients were classified using the ASIA International Neurological Standard. Upper limb function was evaluated using a short version of the Van Lushot Test (VLT). Stimulation electroneuromyography (SENMG) from the median and ulnar nerves was performed. The distribution at the motor level (ML) was as follows: C4-C6 - 117 patients; C7-D1 - 73 patients; depending on the severity of injury (SI): type A and B - 132 patients; upper limb motor score (ASIAarm) was 25.0±12.2, on VLT - 38.3±20.9. The factor loading of 10 factors was evaluated simultaneously in a linear discriminant analysis, the cut-off point was 20 and 40 scores on VLT (25 and 50% on the International Classification of Functioning, Disability and Health without the domain «balance»).

RESULTS

According to SENMG, denervation changes were detected in 15% of median and in 23% of ulnar nerves. The rank significance for the VLT threshold of 20 scores was: ASIA_arm - 100, functional tenodesis (FT) - 91, ML - 73, SI - 18; the classification tree had one branching at the ASIA_arm point of 17.3 score. The rank significance for the threshold of 40 scores was: ASIA_arm - 100, ML - 59, SI - 50, FT - 28, M response from the median nerve - 5; the classification tree had one branching at the ASIA_arm point of 26.9 score. The results of multivariate linear regression analysis confirmed the highest factor loading of ML predictor, motor score for upper limb (ASIA_arm) in both cases (R=0.67, R₂=0.45, F=38.0, p=0.00 and R=0.69, R₂=0.47; F=42.0, p=0.00, respectively).

CONCLUSION

In the late period after a spinal injury the leading predicative value for functional motor activity has the motor score of ASIA for the upper limb. The ASIA score more than 27 scores is the prediction of moderate and mild impairments, and less than 17 - severe impairments.

Handgrip Strength Cutoff Points for Functional Independence and Wheelchair Ability in Men With Spinal Cord Injury

Objectives

To determine optimal handgrip strength (HGS) cutoff points for greater functional independence and wheelchair skills in men with spinal cord injury (SCI), and to establish predictive equations for functional independence and wheelchair ability in men with SCI, based on demographic characteristics, HGS, and functionality.

Methods

In this cross-sectional study conducted at a rehabilitation hospital, 54 men with SCI were recruited and stratified into high and low paraplegia groups. All participants performed a maximum HGS test to determine cutoff points for the Spinal Cord Independence Measure (SCIM-III) and Adapted Manual Wheelchair Circuit (AMWC). The primary outcomes were the SCIM-III, AMWC, and HGS. Demographic characteristics obtained from participants' electronic medical records were the secondary outcomes, used as predictor variables of functional independence.

Results

The SCIM-III scale, performance score, and 3-minute overground wheeling test presented significant regression equations (R = 0.45, R = 0.69, and R = 0.72). The HGS showed a cutoff point of 102.5 kilogram force (kgf) to achieve a score of 70 on the SCIM-III and a 3-minute overground wheeling distance of 270 m. The HGS cutoff point to obtain a performance score of 23.7 seconds was 93.0 kgf.

Conclusion

The HGS was a significant predictor for the SCIM-III score, AMWC performance score, and 3-minute overground wheeling test. Three significant predictive equations were established based on HGS. The cutoff points could be adopted as parameters for optimal functional independence and wheelchair skills.

Neuronal Actions of Transspinal Stimulation on Locomotor Networks and Reflex Excitability During Walking in Humans With and Without Spinal Cord Injury

This study investigated the neuromodulatory effects of transspinal stimulation on soleus H-reflex excitability and electromyographic (EMG) activity during stepping in humans with and without spinal cord injury (SCI). Thirteen able-bodied adults and 5 individuals with SCI participated in the study. EMG activity from both legs was determined for steps without, during, and after a single-pulse or pulse train transspinal stimulation delivered during stepping randomly at different phases of the step cycle. The soleus H-reflex was recorded in both subject groups under control conditions and following single-pulse transspinal stimulation at an individualized exactly similar positive and negative conditioning-test interval. The EMG activity was decreased in both subject groups at the steps during transspinal stimulation, while intralimb and interlimb coordination were altered only in SCI subjects. At the steps immediately after transspinal stimulation, the physiological phase-dependent EMG modulation pattern remained unaffected in able-bodied subjects. The conditioned soleus H-reflex was depressed throughout the step cycle in both subject groups. Transspinal stimulation modulated depolarization of motoneurons over multiple segments, limb coordination, and soleus H-reflex excitability during assisted stepping. The soleus H-reflex depression may be the result of complex spinal inhibitory interneuronal circuits activated by transspinal stimulation and collision between orthodromic and antidromic volleys in the peripheral mixed nerve. The soleus H-reflex depression by transspinal stimulation suggests a potential application for normalization of spinal reflex excitability after SCI.

ORTHOPEDIC RELATED COMORBIDITIES IN SPINAL CORD-INJURED INDIVIDUALS

Objective:

This study aims to review, identify and study the determinations of the main orthopedic aspects in SCI patients.

Methods:

A total of 80 articles from PUBMED and three theses (MSc. /DSc.) were examined.

Results:

The results refer to the most essential joints. There is a chronic overload on the shoulder girdle due to the use of the upper limb as a supporting joint. The elbow presents osteoarthritis, subclinical, acute and chronic pain, mainly in quadriplegic patients. In the hand and wrist joints there are cases of paralysis, osteoporosis and osteoarthritis. Hips are the main weight-bearing joints while sitting which leads to a substantial degenerative process of this joint. Lastly, on the knee, feet and ankles, spasticity, contractures, osteoporosis and deformities can arise.

Conclusion:

Along with the increase in cases and research that analyze the alterations that spinal cord-injured individuals suffer, it is necessary to recognize the orthopedic changes to understand their limits and identify the relevance of the rehabilitation program to improve the muscle performance. Level of Evidence II, Prognostic Studies - Investigating the Effect of a Patient Characteristic on the Outcome of Disease.

Differences of Relative and Absolute Strength of Individuals With Spinal Cord Injury From Able-Bodied Subjects: A Discriminant Analysis

CONTEXT

Strength training is one of the most common interventions employed to increase functional independence during rehabilitation of individuals with spinal cord injury (SCI). However, in the literature, different results have been reported in terms of strength modifications after a SCI compared with a control group (CG).

OBJECTIVE

This study aimed to verify whether discriminant analysis using relative and absolute strength is able to discriminate individuals with different levels of SCI from a CG and to compare strength values of men with different levels of SCI with a CG.

DESIGN

Cross-sectional study.

SETTING

Rehabilitation hospital setting.

PARTICIPANTS

A total of 36 individuals with SCI stratified in tetraplegia (TP; C6-C8), high paraplegia (HP; T1-T6), and low paraplegia (LP; T7-L2), and 12 matched control subjects were enrolled in the study.

MAIN OUTCOME MEASURES

The subjects performed a maximum strength test of elbow extension/flexion and also shoulder abduction/adduction and flexion/extension in an isokinetic dynamometer. Discriminant analysis was carried out to identify which strength variables would be able to discriminate the TP, HP, or LP groups from the CG. A 1-way analysis of variance was performed to compare peak torque and agonist/antagonist ratio means.

RESULTS

Shoulder adduction, followed by elbow extension peak torque, was the best variable for discriminating the TP group from the CG (function coefficients: -0.056 and 0.051, respectively, Wilks Λ = 0.41, P ≤ .05). There were no significant differences between the HP group, LP group, and CG.

CONCLUSIONS

The strength similarity of the paraplegic groups and the CG should not be extrapolated for activities of daily living or sports. The TP group demonstrated lower peak torque for all movements than the CG.

REACH AND PALMAR GRASP IN TETRAPLEGICS WITH NEUROMUSCULAR ELECTRICAL STIMULATION

ABSTRACT Objective: To evaluate the movement strategies of quadriplegics, assisted by neuromuscular electrical stimulation, on reach and palmar grasp using objects of different weights. Methods: It was a prospective clinical trial. Four chronic quadriplegics (C5-C6), with injuries of traumatic origin, were recruited and all of them had their reach and palmar grasp movement captured by four infrared cameras and six retro-reflective markers attached to the trunk and right arm, assisted or not by neuromuscular electrical stimulation to the triceps, extensor carpi radialis longus, extensor digitorum communis, flexor digitorum superficialis, opponens pollicis and lumbricals. It was measured by a Neurological and Functional Classification of Spinal Cord Injuries of the American Spinal Injury Association, Functional Independence Measure and kinematic variables. Results: The patients were able to reach and execute palmar grasp in all cylinders using the stimulation sequences assisted by neuromuscular electrical stimulation. The quadriplegics produced lower peak velocity, a shorter time of movement and reduction in movement segmentation, when assisted by neuromuscular electrical stimulation. Conclusion: This study showed that reach and palmar grasp movement assisted by neuromuscular electrical stimulation was able to produce motor patterns more similar to healthy subjects. Level of evidence IV; Case series.

Rehabilitation of hand function after spinal cord injury using a novel handgrip device: a pilot study

Background

Activity-based therapy (ABT) for patients with spinal cord injury (SCI), which consists of repetitive use of muscles above and below the spinal lesion, improves locomotion and arm strength. Less data has been published regarding its effects on hand function. We sought to evaluate the effects of a weekly hand-focused therapy program using a novel handgrip device on grip strength and hand function in a SCI cohort.

Methods

Patients with SCI were enrolled in a weekly program that involved activities with the MediSens (Los Angeles, CA) handgrip. These included maximum voluntary contraction (MVC) and a tracking task that required each subject to adjust his/her grip strength according to a pattern displayed on a computer screen. For the latter, performance was measured as mean absolute accuracy (MAA). The Spinal Cord Independence Measure (SCIM) was used to measure each subject’s independence prior to and after therapy.

Results

Seventeen patients completed the program with average participation duration of 21.3 weeks. The cohort included patients with American Spinal Injury Association (ASIA) Impairment Scale (AIS) A (n = 12), AIS B (n = 1), AIS C (n = 2), and AIS D (n = 2) injuries. The average MVC for the cohort increased from 4.1 N to 21.2 N over 20 weeks, but did not reach statistical significance. The average MAA for the cohort increased from 9.01 to 21.7% at the end of the study (p = .02). The cohort’s average SCIM at the end of the study was unchanged compared to baseline.

Conclusions

A weekly handgrip-based ABT program is feasible and efficacious at increasing hand task performance in subjects with SCI.