Assessment, management, and rehabilitation of traumatic peripheral nerve injuries for non-surgeons

Electrodiagnostic evaluation is often requested for persons with peripheral nerve injuries and plays an important role in their diagnosis, prognosis, and management. Peripheral nerve injuries are common and can have devastating effects on patients' physical, psychological, and socioeconomic well-being; alongside surgeons, electrodiagnostic medicine specialists serve a central function in ensuring patients receive optimal treatment for these injuries. Surgical intervention-nerve grafting, nerve transfers, and tendon transfers-often plays a critical role in the management of these injuries and the restoration of patients' function. Increasingly, nerve transfers are becoming the standard of care for some types of peripheral nerve injury due to two significant advantages: first, they shorten the time to reinnervation of denervated muscles; and second, they confer greater specificity in directing motor and sensory axons toward their respective targets. As the indications for, and use of, nerve transfers expand, so too does the role of the electrodiagnostic medicine specialist in establishing or confirming the diagnosis, determining the injury's prognosis, recommending treatment, aiding in surgical planning, and supporting rehabilitation. Having a working knowledge of nerve and/or tendon transfer options allows the electrodiagnostic medicine specialist to not only arrive at the diagnosis and prognosticate, but also to clarify which nerves and/or muscles might be suitable donors, such as confirming whether the branch to supinator could be a nerve transfer donor to restore distal posterior interosseous nerve function. Moreover, post-operative testing can determine if nerve transfer reinnervation is occurring and progress patients' rehabilitation and/or direct surgeons to consider tendon transfers.

Possible donor nerves for axillary nerve reconstruction in dual neurotization for restoring shoulder abduction in brachial plexus injuries: a systematic review and meta-analysis

Restoring shoulder abduction is one of the main priorities in the surgical treatment of brachial plexus injuries. Double nerve transfer to the axillary nerve and suprascapular nerve is widely used and considered the best option. The most common donor nerve for the suprascapular nerve is the spinal accessory nerve. However, donor nerves for axillary nerve reconstructions vary and it is still unclear which donor nerve has the best outcome. The aim of this study was to perform a systematic review on reconstructions of suprascapular and axillary nerves and to perform a meta-analysis investigating the outcomes of different donor nerves on axillary nerve reconstructions. We conducted a systematic search of English literature from March 2001 to December 2020 following PRISMA guidelines. Two outcomes were assessed, abduction strength using the Medical Research Council (MRC) scale and range of motion (ROM). Twenty-two studies describing the use of donor nerves met the inclusion criteria for the systematic review. Donor nerves investigated included the radial nerve, intercostal nerves, medial pectoral nerve, ulnar nerve fascicle, median nerve fascicle and the lower subscapular nerve. Fifteen studies that investigated the radial and intercostal nerves met the inclusion criteria for a meta-analysis. We found no statistically significant difference between either of these nerves in the abduction strength according to MRC score (radial nerve 3.66 ± 1.02 vs intercostal nerves 3.48 ± 0.64, p = 0.086). However, the difference in ROM was statistically significant (radial nerve 106.33 ± 39.01 vs. intercostal nerve 80.42 ± 24.9, p < 0.001). Our findings support using a branch of the radial nerve for the triceps muscle as a donor for axillary nerve reconstruction when possible. Intercostal nerves can be used in cases of total brachial plexus injury or involvement of the C7 root or posterior fascicle. Other promising methods need to be studied more thoroughly in order to validate and compare their results with the more commonly used methods.

Defining the Reliability of Deltoid Reanimation by Nerve Transfer When Using Abnormal but Variably Recovered Triceps Donor Nerves

Upper brachial plexus injuries to the C5/6 roots or axillary nerve can result in severe deficits in upper limb function. Current techniques to reinnervate the deltoid muscle utilise the well-described transfer of radial nerve branches to triceps to the axillary nerve. However, in around 25% of patients, there is a failure of sufficient deltoid reinnervation. It is unclear in the literature if deltoid reanimation should be attempted with a nerve transfer from a weak but functioning triceps nerve. The authors present the largest series of triceps to axillary nerve transfers for deltoid reanimation in order to answer this clinical question. Seventy-seven consecutive patients of a single surgeon were stratified and analysed in four groups: (1) normal triceps at presentation, (2) abnormal triceps at presentation recovering to clinically normal function preoperatively, (3) abnormal triceps at presentation remaining abnormal preoperatively, and lastly (4) where pre-operative triceps function was deemed insufficient for use, requiring alternative reconstruction for deltoid reanimation. The authors considered deltoid re-animation of ≥ M4 as successful for the purpose of this study. Median Medical Research Council (MRC) values demonstrate group 1 achieves this successfully (M5), while median values for groups 2-4 result in M4 power (albeit with decreasing interquartile ranges). Median post-operative shoulder abduction active range of motion (AROM) values were represented by 170° (85-180) in group 1, 117.5° (97.5-140) in group 2, 90° (35-150) in group 3, and 60° (40-155) in group 4. For both post-operative assessments, subgroup analyses demonstrated statistically significant differences when comparing group 1 with groups 3 and 4 (p < 0.05), while all the other group to group pairwise comparisons did not reach significance. The authors postulated that triceps deficiency can act as a surrogate marker of a more extensive plexus injury and may predict poorer outcomes if the weakness persists representing the trending differences between groups 2 and 3. However, given no statistical differences were demonstrated between groups 3 and 4, the authors conclude that utilising an abnormal triceps nerve that demonstrates sufficient strength and redundancy intraoperatively is preferable to alternative transfers for deltoid reanimation. Lastly, in group 4 patients where triceps nerves are damaged and unusable for nerve transfer, alternative operations can also achieve sufficient outcomes and should be considered for restoration of shoulder abduction.

MRI evaluation of axillary neurovascular bundle: Implications for minimally invasive proximal humerus fracture fixation

Background

Percutaneous fixation of proximal humeral fractures places the axillary nerve and posterior humeral circumflex artery at risk for injury. Safe operative zones for the axillary nerve are described based on external measurements from anatomic landmarks, but no study to date has incorporated advanced imaging to help guide surgical procedures in the region of the axillary neurovascular bundle (ANVB). We sought to define the location and trajectory of the ANVB in relation to osseous landmarks using magnetic resonance imaging (MRI) measurements.

Methods

Retrospective review of 750 consecutive MRI studies was performed with 55 imaging studies meeting inclusion criteria for patient positioning, image alignment, and quality. Five measurements were performed including the distance from mid-lateral acromion to lateral ANVB, mid-lateral acromion to medial ANVB, greater tuberosity to lateral ANVB, vertical distance between inferior anatomic neck and lateral ANVB, and angle the ANVB crosses the humerus. Height, gender, and age were recorded. Analysis was performed using ANOVA and Pearson correlation tests.

Results

The lateral ANVB was below the inferior articular margin of the humeral head by an average of 12.9 ± 3.9 mm and within a 22 mm window. It was an average of 57.4 ± 5.1 mm from the lateral mid-acromion, and 34.7 ± 4.3 mm below the greater tuberosity. The angle formed by the ANVB crossing the humerus averaged 19.5 ± 3.9 degrees upward from medial to lateral. Height and gender directly impacted measurements.

Conclusions

The use of the inferior humeral head articular margin provides a radiographic landmark to aid intraoperative lateral ANVB assessment which may be helpful during percutaneous fracture fixation.

Isolated Axillary Nerve Rupture due to Closed Nondislocating Injury of the Shoulder in Contact Sports: A Report of 2 Cases

CASE

Axillary nerve rupture without shoulder joint fracture or dislocation in contact sports is very rare. To date, there has been no detailed report on such cases. We present 2 rare cases of axillary nerve rupture in contact sports who were successfully treated with free nerve grafting.

CONCLUSION

In contact sports, the deltoid muscle is sometimes paralyzed temporarily after a collision. However, similar to our cases, the axillary nerve can be lacerated without fracture or dislocation. It is necessary to watch the course of paralysis carefully and consider nerve reconstruction if it does not recover.

Isolated Axillary Nerve Injury in an Elite High School American Football Player: A Case Report

An elite high school American football athlete sustained a traumatic, isolated, axillary nerve injury. Axillary nerve injuries are uncommon, but serious injuries in American football. With the advent of nerve transfers and grafts, these injuries, if diagnosed in a timely manner, are treatable. This case report discusses the multidisciplinary approach necessary for the diagnosis and treatment of an elite high school American football player who presented with marked deltoid atrophy. The athlete's injury was diagnosed via electrodiagnostic testing and he underwent a medial triceps nerve to axillary nerve transfer. After appropriate postsurgical therapy, the athlete was able to return to American football the subsequent season and continue performing at an elite level. This case report reviews the evaluation and modern treatment for axillary nerve injuries in the athlete, including nerve transfers, nerve grafts, and return to play.

Nerve Transfer versus Interpositional Nerve Graft Reconstruction for Posttraumatic, Isolated Axillary Nerve Injuries: A Systematic Review

BACKGROUND

The purpose of this study was to compare functional outcomes between nerve grafting and nerve transfer procedures in the setting of isolated, posttraumatic axillary nerve injuries.

METHODS

A systematic review was performed using the PubMed, Scopus, and Cochrane databases to identify all cases of isolated, posttraumatic axillary nerve injuries in patients aged 18 years or older. Patients who underwent axillary nerve reconstruction were included and categorized by technique: graft or transfer. Demographics were recorded, including age, time to operation, and presence of concomitant injuries. Functional outcomes were evaluated, including British Medical Research Council strength and range of motion for shoulder abduction.

RESULTS

Ten retrospective studies met criteria, for a total of 66 patients (20 nerve grafts and 46 nerve transfers). Median time from injury to operation was equivalent across the nerve graft and nerve transfer groups (8.0 months versus 7.0 months; p = 0.41). Postoperative follow-up was 24.0 months for nerve grafting versus 18.5 months for nerve transfer (p = 0.13). Clinically useful shoulder abduction, defined as British Medical Research Council grade M3 or greater, was obtained in 100 percent of nerve graft patients versus 87 percent of nerve transfer patients (p = 0.09). Grade M4 or better strength was obtained in 85 percent of nerve graft patients and 73.9 percent of nerve transfer patients (p = 0.32).

CONCLUSIONS

Significant differences in functional outcomes between nerve graft and transfer procedures for posttraumatic axillary nerve injuries are not apparent at this time. Prospective outcomes studies are needed to better elucidate whether functional differences do exist.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Nerve Transfers to Restore Shoulder Function

The restoration of shoulder function after brachial plexus injury represents a significant challenge facing the peripheral nerve surgeons. This is owing to a combination of the complex biomechanics of the shoulder girdle, the multitude of muscles and nerves that could be potentially injured, and a limited number of donor options. In general, nerve transfer is favored over tendon transfer, because the biomechanics of the musculotendinous units are not altered. This article summarizes the surgical techniques and clinical results of nerve transfers for restoration of shoulder function.