Evidence for efficacy of new developments in reconstructive upper limb surgery for tetraplegia

A Mixed Methods Approach as a Channel to Interpret Outcomes Research and Lived Experience Enquiry of Upper Extremity Elective Surgery for Tetraplegia

Cervical spinal cord injury (SCI) causing tetraplegia is extremely disabling. In such circumstances, restoration of upper extremity (UE) function is considered the highest priority. The advent of early nerve transfer (NT) procedures, in addition to more traditional tendon transfers (TT), warranted in-depth consideration given the time-limited nature of NT procedures. Potential surgery candidates may not yet have come to terms with the permanence of their disability. A mixed methods convergent design was utilized for concurrent analysis of the Aotearoa/New Zealand upper limb registry data from the clinical assessments of all individuals considering UE surgery, regardless of their final decision. The International Classification of Functioning, Disability and Health (ICF) taxonomy guided data interpretation during the three-phased study series. It was the integration of the findings using the Stewart Model of care drawn from palliative health that enabled the interpretation of higher order messages. It is clear the clinical assessment and selection processes in use require reconsideration given the complexities individuals face following onset of SCI. We draw attention to the higher order cognitive demands placed on individuals, the requirement for SCI peer involvement in decision making and the need for acknowledgment of interdependence as a relational construct when living with tetraplegia.

The Anatomy of Nerve Transfers Used in Tetraplegic Hand Reconstruction

PURPOSE

To evaluate the anatomy of nerve transfers used to reconstruct wrist extension, hand opening, and hand closing in tetraplegic patients.

METHODS

Nerve transfers were completed on 18 paired cadaveric upper limbs. The overlap of donor and recipient nerves was measured, as well as the distance to the target muscle. Axons were counted in each nerve and branch, with the axon percentage calculated by dividing the donor nerve count by that of the recipient.

RESULTS

Transfers with overlap of the donor and recipient nerve were from the radial nerve branch to extensor carpi radialis brevis to anterior interosseous nerve (AIN) and from the branch(es) to supinator to posterior interosseous nerve. The extensor carpi radialis brevis to AIN had the shortest distance to the target, with the branch to brachialis to AIN being the longest. The nerve transfers for wrist extension had the highest axon percentage. Of the transfers for hand closing, the brachialis to AIN had the highest axon percentage, and the branch to brachioradialis to AIN had the lowest.

CONCLUSIONS

The anatomical features of nerve transfers used in tetraplegic hand reconstruction are variable. Differences may help explain clinical outcomes.

CLINICAL RELEVANCE

This study demonstrates which nerve transfers may be anatomically favorable for restoring hand function in tetraplegic patients.

Pre-operative electrodiagnostic planning for upper limb peripheral nerve transfers in cervical spinal cord injury: A Narrative Review

Peripheral nerve transfer (PNT) to improve upper limb function following cervical spinal cord injury (SCI) involves the transfer of supralesional donor nerves under voluntary control to intralesional or sublesional lower motor neurons not under voluntary control. Appropriate selection of donor and recipient nerves and surgical timing impact functional outcomes. While the gold standard of nerve selection is intra-operative nerve stimulation, preoperative electrodiagnostic (EDX) evaluation may help guide surgical planning. Currently there is no standardized preoperative EDX protocol. This study reviews the EDX workup preceding peripheral nerve transfer surgery in cervical SCI, and proposes an informed EDX protocol to assist with surgical planning. The PICO (Population, Intervention, Comparison, Outcome) framework was used to formulate relevant MeSH terms and identify published cases of PNT in cervical SCI in Medline, Embase, CINAHL, and Emcare databases in the last 10 years. The electrodiagnostic techniques evaluating putative donor nerves, recipient nerve branches, time-sensitivity of nerve transfer and other electrophysiological parameters were summarized to guide creation of a preoperative EDX protocol. Needle electromyography (EMG) was the most commonly used EDX technique to identify healthy donor nerves. Although needle EMG has also been used on recipient nerves, compound muscle action potential (CMAP) amplitudes may provide a more accurate determination of recipient nerve health and time-sensitivity for nerve transfer. While there has been progress in pre-surgical EDX evaluation, EMG and NCS approaches are quite variable, and each has limitations in their utility for pre-operative planning. There is need for standardization in the EDX evaluation preceding peripheral nerve transfer surgery to assist with donor and recipient nerve selection, surgical timing and to optimize outcomes. Based on results of this review, herein we propose the PreSCIse (PRotocol for Electrodiagnosis in SCI Surgery of the upper Extremity) pre-operative EDX panel to achieve said goals through an interdisciplinary and patient-centered approach. This article is protected by copyright. All rights reserved.

Functional outcome after transfer of brachialis on anterior interosseous and supinator on posterior interosseous nerves: A preliminary report

OBJECTIVE

Traumatic spinal cord injury (SCI) resulting in tetraplegia is a leading cause of morbidity among young adults worldwide and its management remains challenging. Restoring hand function in these patients must be considered a top priority with great impact on their quality of life (QOL); although nerve and tendon transfer have been extensively described, type of procedure to be chosen is not standardized and few studies have determined the functional outcome of those procedure and their impact on QOL is still poorly assessed. We report a preliminary retrospective study regarding feasibility and functional outcomes of nerve transfer procedures including bilateral brachialis nerve on anterior interosseous nerve (AIN) and supinator branch on posterior interosseous nerve (PIN) for hand reanimation following SCI focusing on the impact of these procedures on QOL.

METHODS

We performed a retrospective study involving patient sustained SCI and underwent nerve transfer of brachialis branch from musculocutaneous nerve on AIN and supinator branch from the trunk of the radial nerve on the PIN. We included 11 patients (14 limbs) with traumatic SCI resulting in C4 level tetraplegia in five patients, C5 in four and C6 and C7 in one case each, with a median age of 31.5 years underwent surgery at a median of 10 months after injury; including both transfers in 10 cases and AIN reanimation only in one. Functional assessment including medical research council (MCR) grade, graded redefined assessment of strength sensation and prehension (GRASSP) and spinal cord independence measure (SCIM) were performed at least 12 months follow up.

RESULTS

Thirteen PIN innervated muscles achieved an MRC score ≥3/5 whereas AIN supplied muscles in 5 out of 15. GRASSP qualitative measure improved from a baseline value of 1 to 2, while quantitative measure passed from 1 to 3 after 12 months; the difference was statistically significant (p = .005 and p = .008, respectively). SCIM self-care sub-score also statistically significant improved from 3 to 4 at 12 months (p = .016). No complication or donor morbidity occurred.

CONCLUSIONS

Functional performance has been significantly improved by nerve transfer procedures 1 year after surgery. Nerve transfers may represent a valuable option for the restoration of the hand function in patients with tetraplegia with minor or no morbidity.

Selective transfer of nerve to supinator to restore digital extension in central cord syndrome: An anatomical study and a case report

BACKGROUND

Nerve transfers are increasingly used to restore upper extremity function in patients with spinal cord injury. However, the role of nerve transfers for central cord syndrome is still being established. The purpose of this study is to report the anatomical feasibility and clinical use of nerve transfer of supinator motor branches (NS) to restore finger extension in a central cord syndrome patient.

MATERIALS AND METHODS

The posterior interosseous nerve (PIN), its superficial division, and branches were dissected in 14 fresh cadavers, with a mean age of 65 (58-79). Measurements included number and length of branches of donor and recipient, diameters, regeneration distance from coaptation site to motor entry point and axonal counts. A NS transfer to extensor carpi ulnaris (ECU), extensor digiti quinti (EDQ) and extensor digitorum communis (EDC) was performed in a 28-year-old patient, with central cord syndrome after a motorcycle accident, who did not recover active finger extension at 10 months post injury.

RESULTS

The PIN consistently divided into a deep and superficial branch between 1.5 cm proximal to, and 2 cm distal to the distal boundary of the supinator. The superficial branch provided a first common branch to the ECU and EDQ. In 12/14 dissections, the EDC was innervated by a 4 cm long branch that entered the muscle on its radial deep surface. In all cases, the superficial branch of the PIN could be separated in a retrograde fashion from the PIN and coapted with NS. The mean myelinated fiber count in nerve to EDC was 401 ± 190 compared to 398 ± 75 in the NS. At 48 months after surgery, with the wrist at neutral, the patient recovered full metacarpophalangeal extension scoring M4. Supination was preserved with the elbow extended or flexed.

CONCLUSIONS

Restoration of finger extension in central cord syndrome is possible with a selective transfer of the NS to EDC, and is anatomically feasible with a short regeneration distance and favorable axonal count ratio.

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.

Reanimating hand function after spinal cord injury using nerve transfer surgery

Loss of arm and hand function is a devastating consequence of cervical spinal cord injury. Tendon transfer surgery has traditionally been used to restore key functions including elbow extension, wrist extension and grasp and pinch. The more recent development of nerve transfer surgery enables direct restoration of voluntary control of these functions. While both types of surgery are safe and effective, nerve transfer surgery results in a more open, flexible and natural hand, with more subtle control for a range of activities of daily living.