Advanced Assessment of the Upper Limb in Tetraplegia: A Three-Tiered Approach to Characterizing Paralysis

Preoperative evaluation of nerve transfer recipients after spinal cord injury using stimulated manual muscle testing

Nerve transfer after spinal cord injury has become increasingly popular. Accurate preoperative identification of lower motor neuron involvement in potential recipient nerves is critical. Electrodiagnostic testing has been shown to correlate with intraoperative findings; however, it is time-consuming, costly and may not be readily available. Stimulated manual muscle testing is an alternative diagnostic approach. It is inexpensive and easily done by the surgeon or therapist in the office; however, correlation with intraoperative stimulation has not been reported. A retrospective review was conducted for patients who underwent nerve transfer for tetraplegia with recorded preoperative stimulated manual muscle testing and intraoperative stimulation results. Nine patients including 37 nerve transfers were included. Of the 37 nerve transfers, 36 were accurately graded preoperatively by stimulated manual muscle testing. Stimulated manual muscle testing had a sensitivity of 89%, specificity of 100%, positive predictive value of 100% and a negative predictive value of 97%. This study supports stimulated manual muscle testing for preoperative distinction between upper versus lower motor neuron injuries.Level of evidence: IV.

Neuroprosthesis for individuals with spinal cord injury

OBJECTIVE

Individuals who sustain a traumatic spinal cord injury (SCI) often have a loss of multiple body systems. Significant functional improvement can be gained by individual SCI through the use of neuroprostheses based on electrical stimulation. The most common actions produced are grasp, overhead reach, trunk posture, standing, stepping, bladder/bowel/sexual function, and respiratory functions.

METHODS

We review the fundamental principles of electrical stimulation, which are established, allowing stimulation to be safely delivered through implanted devices for many decades. We review four common clinical applications for SCI, including grasp/reach, standing/stepping, bladder/bowel function, and respiratory functions. Systems used to implement these functions have many common features, but are also customized based on the functional goals of each approach. Further, neuroprosthetic systems are customized based on the needs of each user.

RESULTS & CONCLUSION

The results to date show that implanted neuroprostheses can have a significant impact on the health, function, and quality of life for individuals with SCI. A key focus for the future is to make implanted neuroprostheses broadly available to the SCI population.

Functional electrical stimulation therapy for upper extremity rehabilitation following spinal cord injury: a pilot study

STUDY DESIGN

Pilot study.

OBJECTIVES

To examine if functional electrical stimulation therapy (FEST) improves neuromuscular factors underlying upper limb function in individuals with SCI.

SETTING

A tertiary spinal cord rehabilitation center specialized in spinal cord injury care in Canada.

METHODS

We examined 29 muscles from 4 individuals living with chronic, cervical, and incomplete SCI. The analysis was focused on the changes in muscle activation, as well as on how the treatment could change the ability to control a given muscle or on how multiple muscles would be coordinated during volitional efforts.

RESULTS

There was evidence of gains in muscle strength, activation, and median frequency after the FEST. Gains in muscle activation indicated the activation of a greater number of motor units and gains in muscle median frequency the involvement of higher threshold, faster motor units. In some individuals, these changes were smaller but accompanied by increased control over muscle contraction, evident in a greater ability to sustain a volitional contraction, reduce the co-contraction of antagonist muscles, and provide cortical drive.

CONCLUSIONS

FEST increases muscle strength and activation. Enhanced control of muscle contraction, reduced co-contraction of antagonist muscles, and a greater presence of cortical drive were some of the findings supporting the effects of FEST at the sensory-motor integration level.

[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.

Clinical electrodiagnostic evaluation for nerve transfer surgery in spinal cord injury: a new indication and clinical pearls

In this review, we highlight the important role of the clinical electrodiagnostic (EDX) evaluation after cervical spinal cord injury (SCI). Our discussion focuses on the need for timely, frequent, and accurate EDX evaluations in the context of nerve transfer surgery to restore critical upper limb functions, including elbow extension, hand opening, and hand closing. The EDX evaluation is crucial to define the extent of lower motor neuron lesions and determine candidacy for surgery. We also discuss the important role of the postoperative EDX evaluation in determining prognosis and supporting rehabilitation. We propose a practical framework for EDX evaluation in this clinical setting.

Improving hand function after spinal cord injury

Nerve transfer surgery has expanded reconstructive options for restoring upper extremity function following spinal cord injury. By adding new motor donors to the pool already available through tendon transfers, the effectiveness of treatment should improve. Planning which procedures and in which order to perform, along with their details must be delineated. To meet these demands, refined diagnostics are needed, along with awareness of the remaining challenges to restore intrinsic muscle function and to address spasticity and its consequences. This article summaries recent advances in surgical reanimation of upper extremity motor control, together with an overview of the development of neuro-prosthetic and neuromodulation techniques to modify recovery or substitute for functional losses after spinal cord injuries.

Can Magnetic Resonance Imaging Reveal Lower Motor Neuron Damage after Traumatic Spinal Cord Injury? A Scoping Review

Restoring muscle function to patients with spinal cord injuries (SCIs) will invariably require a functioning lower motor neuron (LMN). As techniques such as nerve transfer surgery emerge, characterizing the extent of LMN damage associated with SCIs becomes clinically important. Current methods of LMN diagnosis have inherent limitations that could potentially be overcome by the development of magnetic resonance imaging (MRI) biomarkers: specific features on MRI that are indicative of LMN integrity. To identify research on MRI biomarkers of LMN damage in the acute phase after SCI, we searched PubMed, EMBASE, MEDLINE, and the Cochrane Central Register of Controlled Trials for articles published from inception to April 27, 2021. Overall, 2 of 58 unique articles screened met our inclusion criteria, both of which were small studies. We therefore identify MRI biomarkers of LMN damage overlying SCI as a notable gap in the literature. Because of the lack of existing literature on this specific problem, we further our discussion by examining concepts explored in research characterizing MRI biomarkers of spinal cord and neuronal damage in different contexts that may provide value in future work to identify a biomarker for LMN damage in SCI. We conclude that MRI biomarkers of LMN damage in SCI is an underexplored, but promising, area of research as emerging, function-restoring therapies requiring this information continue to advance.

Lower Motor Neuron Abnormality in Chronic Cervical Spinal Cord Injury: Implications for Nerve Transfer Surgery

Nerve transfer surgery (NT) constitutes an exciting option to improve upper limb functions in chronic spinal cord injury (SCI), but requires intact sublesional lower motor neuron (LMN) health. The purpose of this study was to characterize patterns of LMN abnormality in nerve-muscle groups that are the potential recipients of NT, using a standardized electrodiagnostic examination, in individuals with chronic SCI (injury duration >2 years, injury levels C4-T1). The LMN abnormality was determined using a semihierarchical approach, combining the amplitude compound muscle action potential (CMAP) and abnormal spontaneous activity on needle electromyography (EMG). Ten participants (46 potential recipient muscles) were included (median age, 42.5 years; six males and four females; median duration from injury, 15.5 years). A high frequency of LMN abnormality was observed (87%), although there was substantial variation within and between individuals. No statistically significant discordance was observed between LMN abnormality on CMAP and EMG (p = 0.24), however, 50% of muscles with normal CMAP demonstrated abnormal spontaneous activity. The high frequency of LMN abnormality in recipient nerve-muscle groups has implications to candidate selection for NT surgery in chronic SCI and supports the important role of the pre-operative electrodiagnostic examination. Our results further support the inclusion of both CMAP and needle EMG parameters for characterization of LMN health. Although the number of nerve-muscle groups with normal LMN health was small (13%), this underscores the neurophysiological potential of some patients with chronic injuries to benefit from NT surgery.