Spontaneous Motor Recovery after Cervical Spinal Cord Injury: Issues for Nerve Transfer Surgery Decision Making

Surgical Strategies for Functional Upper Extremity Reconstruction After Spinal Cord Injury

Spinal cord injuries (SCI) can substantially affect independence and quality of life, particularly by limiting upper extremity function. Surgical reconstruction offers the potential to restore motion in the hand, wrist, and elbow for those with deficits following cervical spinal cord injury. Techniques such as tendon transfer, tenodesis, and arthrodesis-often used in combination-are well-established strategies for enhancing upper extremity function. Nerve transfers have more recently been employed and differ from other procedures in that they are often time sensitive and should be performed before permanent muscle atrophy occurs. A comprehensive preoperative evaluation, including clinical examination and electrodiagnostic assessment, is essential to determine the availability and strength of donor tendons and nerves. The International Classification of Surgery for the Hand in Tetraplegia (ICSHT) system is the most utilized surgical classification for determining muscle that can be used for reconstruction. Based on this classification, prioritization is given to restoring elbow extension, wrist extension, pinch, and grasp. Postoperative rehabilitative therapy balances the need for immobilization while preventing joint stiffness and may also incorporate cortical retraining strategies to activate tendon and nerve transfers. Ultimately, a collaborative, interdisciplinary approach is essential for assessing the injury, determining operative candidacy, selecting the optimal treatment strategy, and providing tailored rehabilitation. This article explores the classification of SCI as it pertains to the upper limb, provides an overview of surgical options, describes the preoperative clinical and electrodiagnostic evaluation process, and discusses reconstructive strategies aimed at improving functional outcomes in individuals with SCI.

Ulnar compound muscle action potentials predict hand muscle strength 1 year after cervical spinal cord injury: A retrospective analysis

BACKGROUND

Lower motor neuron (LMN) dysfunction caused by anterior horn cell damage in the ventral gray matter during spinal cord injury (SCI) may impact long-term prognosis.

OBJECTIVES

To determine the influence of the 3-month ulnar compound muscle action potentials (CMAP; representative of C8-T1 spinal segmental LMN integrity) on hand muscle strength and function, 12 months following SCI.

METHODS

We completed retrospective analyses of the European Multicenter Study about SCI (EMSCI) database. Included participants had traumatic SCI (motor complete or incomplete), initial neurological level of injury C1-C8, and ulnar CMAP from the abductor digiti minimi in at least one limb, 3 months after injury. We trichotomized 3-month ulnar CMAP into absent (CMAP = 0.0 mV), reduced (CMAP <6.0 mV), and normal (CMAP ≥6.0 mV), and constructed logistical regression models to predict 12-month C8 and T1 motor scores, dichotomized into poor (≤3) and functional (>3). We explored relationships between trichotomized 3-month ulnar CMAP and 12-month functional Graded Redefined Assessment of Strength, Sensation and Prehension (GRASSP) and Spinal Cord Independence Measure (SCIM) upper limb sub-scales, using non-parametric statistics.

RESULTS

Data from 318 participants (253 males), 46.8 years old (SD 18.4), resulted in CMAP and corresponding motor scores in 629 limbs. Adjusted logistical regression models were significant for C8 and T1 motor scores, with absent (C8 36.6, 95 % CI 12.9-133; T1 38.7, 95 % CI 11.2-24) and reduced (C8 11.0, 95 % CI 6.7-18.4; T1 7.93, 95 % CI 5.2-12.3) CMAP, predictive of poor 12-month motor scores. 12-month GRASSP (n = 30) and SCIM scores were significantly higher in those with normal 3-month ulnar CMAPs than absent and reduced.

CONCLUSION

There is a 7 to 38-fold higher likelihood that SCI individuals with reduced or absent 3-month ulnar CMAP will demonstrate poor hand motor scores at 12 months. This aligns with significantly worse GRASSP and SCIM functional scores. Our findings justify adding LMN health measures in prognostic modeling after SCI.

A quality improvement initiative to develop an interprofessional peripheral nerve transfer clinic for individuals with traumatic cervical spinal cord injury

PURPOSE

Loss of upper extremity (UE) function impacts almost every aspect of daily life and upper limb recovery is reported to be a major priority of individuals living with tetraplegia. Surgical peripheral nerve transfer (PNT) offers the potential to restore volitional control of elbow, wrist and hand function of individuals with C5-C8 tetraplegia AIS A-C. Unfortunately, while there is growing evidence supporting the role of PNT in spinal cord injury (SCI) rehabilitation, there are currently no internationally-recognized consensus-derived best practices for provision of PNT following spinal cord injury (SCI) and few programs have focused on interdisciplinary collaboration during patient selection, surgical decision making, management of medical comorbidities and postoperative rehabilitation. This quality improvement initiative aimed to establish a novel, interdisciplinary PNT program with the goal of optimizing UE recovery and function in individuals with tetraplegia in Canada.

MATERIALS AND METHODS

An interprofessional team assembled to complete a detailed exploration of care segments, organizing and sequencing care delivery.

RESULTS AND CONCLUSIONS

As a result of this initiative, a care map of planned interprofessional services, their optimal timing across the continuum of care, and clinical functional and community integration outcomes were developed. Data collection and program evaluation are ongoing, and further work to mitigate barriers and develop educational materials around PNT surgery are intended to improve medical decision making and best practice implementation.

Upper Extremity Nerve Transfers for Treatment of Nerve Injury After Cervical Spine Surgery: A Single-Center Retrospective Review

PURPOSE

Nerve transfers to restore or augment function after spinal cord injury is an expanding field. There is a paucity of information, however, on the use of nerve transfers for patients having undergone spine surgery. The incidence of neurologic deficit after spine surgery is rare but extremely debilitating. The purpose of this study was to describe the functional benefit after upper extremity nerve transfers in the setting of nerve injury after cervical spine surgery.

METHODS

A single-center retrospective review of all patients who underwent nerve transfers after cervical spine surgery was completed. Patient demographics, injury features, spine surgery procedure, nerve conduction and electromyography study results, time to referral to nerve surgeon, time to surgery, surgical technique and number of nerve transfers performed, complications, postoperative muscle testing, and subjective outcomes were reviewed.

RESULTS

Fourteen nerve transfers were performed in 6 patients after cervical spine surgery. Nerve transfer procedures consisted of a transfer between a median nerve branch of flexor digitorum superficialis into a biceps nerve branch, an ulnar nerve branch of flexor carpi ulnaris into a brachialis nerve branch, a radial nerve branch of triceps muscle into the axillary nerve, and the anterior interosseous nerve into the ulnar motor nerve. Average patient age was 55 years; all patients were male and underwent surgery on their left upper extremity. Average referral time was 7 months, average time to nerve transfer was 9 months, and average follow-up was 21 months. Average preoperative muscle grading was 0.9 of 5, and average postoperative muscle grading was 4.1 of 5 ( P < 0.00001).

CONCLUSIONS

Upper extremity peripheral nerve transfers can significantly help patients regain muscle function from deficits secondary to cervical spine procedures. The morbidity of the nerve transfers is minimal with measurable improvements in muscle function.

Impact of Upper Limb Motor Recovery on Functional Independence After Traumatic Low Cervical Spinal Cord Injury

Cervical spinal cord injury (SCI) causes devastating loss of upper limb function and independence. Restoration of upper limb function can have a profound impact on independence and quality of life. In low-cervical SCI (level C5-C8), upper limb function can be restored via reinnervation strategies such as nerve transfer surgery. The translation of recovered upper limb motor function into functional independence in activities of daily living (ADLs), however, remains unknown in low cervical SCI (i.e., tetraplegia). The objective of this study was to evaluate the association of patterns in upper limb motor recovery with functional independence in ADLs. This will then inform prioritization of reinnervation strategies focused to maximize function in patients with tetraplegia. This retrospective study performed a secondary analysis of patients with low cervical (C5-C8) enrolled in the SCI Model Systems (SCIMS) database. Baseline neurological examinations and their association with functional independence in major ADLs-i.e., eating, bladder management, and transfers (bed/wheelchair/chair)-were evaluated. Motor functional recovery was defined as achieving motor strength, in modified research council (MRC) grade, of ≥ 3 /5 at one year from ≤ 2/5 at baseline. The association of motor function recovery with functional independence at one-year follow-up was compared in patients with recovered elbow flexion (C5), wrist extension (C6), elbow extension (C7), and finger flexion (C8). A multi-variable logistic regression analysis, adjusting for known factors influencing recovery after SCI, was performed to evaluate the impact of motor function at one year on a composite outcome of functional independence in major ADLs. Composite outcome was defined as functional independence measure score of 6 or higher (complete independence) in at least two domains among eating, bladder management, and transfers. Between 1992 and 2016, 1090 patients with low cervical SCI and complete neurological/functional measures were included. At baseline, 67% of patients had complete SCI and 33% had incomplete SCI. The majority of patients were dependent in eating, bladder management, and transfers. At one-year follow-up, the largest proportion of patients who recovered motor function in finger flexion (C8) and elbow extension (C7) gained independence in eating, bladder management, and transfers. In multi-variable analysis, patients who had recovered finger flexion (C8) or elbow extension (C7) had higher odds of gaining independence in a composite of major ADLs (odds ratio [OR] = 3.13 and OR = 2.87, respectively, p < 0.001). Age 60 years (OR = 0.44, p = 0.01), and complete SCI (OR = 0.43, p = 0.002) were associated with reduced odds of gaining independence in ADLs. After cervical SCI, finger flexion (C8) and elbow extension (C7) recovery translate into greater independence in eating, bladder management, and transfers. These results can be used to design individualized reinnervation plans to reanimate upper limb function and maximize independence in patients with low cervical SCI.

Nerve Transfer After Cervical Spinal Cord Injury: Who Has a "Time Sensitive" Injury Based on Electrodiagnostic Findings?

OBJECTIVE

To use the ulnar compound muscle action potential (CMAP) to abductor digiti minimi (ADM) to identify the proportion of individuals with cervical spinal cord injury (SCI) who have lower motor neuron (LMN) abnormalities involving the C8-T1 spinal nerve roots, within 3-6 months, and thus may influence the response to nerve transfer surgery.

DESIGN

Retrospective analysis of prospectively collected data. Data were analyzed from European Multicenter Study About SCI database.

SETTING

Multi-center, academic hospitals.

PARTICIPANTS

We included 79 subjects (age=41.4±17.7, range:16-75; 59 men; N=79), who were classified as cervical level injuries 2 weeks after injury and who had manual muscle strength examinations that would warrant consideration for nerve transfer (C5≥4, C8<3).

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

The ulnar nerve CMAP amplitude to ADM was used as a proxy measure for C8-T1 spinal segment health. CMAP amplitude was stratified into very abnormal (<1.0 mV), sub-normal (1.0-5.9 mV), and normal (>6.0 mV). Analysis took place at 3 (n=148 limbs) and 6 months (n=145 limbs).

RESULTS

At 3- and 6-month post-injury, 33.1% and 28.3% of limbs had very abnormal CMAP amplitudes, respectively, while in 54.1% and 51.7%, CMAPs were sub-normal. Median change in amplitude from 3 to 6 months was 0.0 mV for very abnormal and 1.0 mV for subnormal groups. A 3-month ulnar CMAP <1 mV had a positive predictive value of 0.73 (95% CI 0.69-0.76) and 0.78 (95% CI 0.75-0.80) for C8 and T1 muscle strength of 0 vs 1 or 2.

CONCLUSION

A high proportion of individuals have ulnar CMAPs below the lower limit of normal 3- and 6-month post cervical SCI and may also have intercurrent LMN injury. Failure to identify individuals with LMN denervation could result in a lost opportunity to improve hand function through timely nerve transfer surgeries.

[Surgical reconstruction of arm and hand functions in tetraplegia : Current concepts]

The reconstruction of arm and hand functions is of enormous importance for tetraplegic patients as it enables at least some degree of independence. Depending on the level of the spinal cord injury, certain residual functions are present in the arms which can be used for surgical reconstruction of upper extremity functions. By utilizing tendon and nerve transfers missing functions can at least be partially reconstructed. Tendon transfers are a proven technique with reliable results that can be performed at any time regardless of the type of accident. Due to the frequent presence of lower motor neuron damage, it is essential to consider the optimal time window for nerve transfer interventions. From the multitude of surgical options, an individual reconstruction plan must be created for each patient, which considers multiple factors. The combination of nerve transfers and later completing the functional reconstruction by tendon transfers is the preferred concept of the authors of this article.

Assessing an Online Patient Decision Aid about Upper Extremity Reconstructive Surgery for Cervical Spinal Cord Injury: Pilot Testing Knowledge, Decisional Conflict, and Acceptability

Background. While nerve and tendon transfer surgery can restore upper extremity function and independence after midcervical spinal cord injury, few individuals (∼14%) undergo surgery. There is limited information regarding these complex and time-sensitive treatment options. Patient decision aids (PtDAs) convey complex health information and help individuals make informed, preference-consistent choices. The purpose of this study is to evaluate a newly created PtDA for people with spinal cord injury who are considering options to optimize upper extremity function. Methods. The PtDA was developed by our multidisciplinary group based on clinical evidence and the Ottawa Decision Support Framework. A prospective pilot study enrolled adults with midcervical spinal cord injury to evaluate the PtDA. Participants completed surveys about knowledge and decisional conflict before and after viewing the PtDA. Acceptability measures and suggestions for further improvement were also solicited. Results. Forty-two individuals were enrolled and completed study procedures. Participants had a 20% increase in knowledge after using the PtDA (P < 0.001). The number of participants experiencing decisional conflict decreased after viewing the PtDA (33 v. 18, P = 0.001). Acceptability was high. To improve the PtDA, participants suggested adding details about specific surgeries and outcomes. Limitations. Due to the COVID-19 pandemic, we used an entirely virtual study methodology and recruited participants from national networks and organizations. Most participants were older than the general population with a new spinal cord injury and may have different injury causes than typical surgical candidates. Conclusions. A de novo PtDA improved knowledge of treatment options and reduced decisional conflict about reconstructive surgery among people with cervical spinal cord injury. Future work should explore PtDA use for improving knowledge and decisional conflict in the nonresearch, clinical setting.

Highlights

People with cervical spinal cord injury prioritize gaining upper extremity function after injury, but few individuals receive information about treatment options.A newly created patient decision aid (PtDA) provides information about recovery after spinal cord injury and the role of traditional tendon and newer nerve transfer surgery to improve upper extremity upper extremity function.The PtDA improved knowledge and decreased decisional conflict in this pilot study.Future work should focus on studying dissemination and implementation of the ptDA into clinical practice.