Ballistic peripheral nerve injuries: basic concepts, controversies, and proposal for a management strategy

"Natural history of low velocity ballistic nerve injuries to the humerus"

OBJECTIVES

To assess ballistic humerus fractures with nerve injuries, their associated characteristics, and functional recovery.

DESIGN

Retrospective review SETTING: Level 1 trauma center over 10-year period.

PATIENTS

143 patients presenting with low-velocity ballistic humerus fractures.

INTERVENTION

Operative intervention and clinical examination of nerve function.

MAIN OUTCOME MEASUREMENTS

Nerve injury incidence and recovery.

RESULTS

The overall incidence of nerve injury was 21% (30 injuries/143 fractures) with 66.7% of fractures treated operatively. Nerve injury varied based on anatomic region: 28.6% (12/42) distal humerus; 20% (15/75) shaft and, 11.5% (3/26) proximal humerus. Arterial injury (p = 0.011) and bone loss (p = 0.0001) were significantly associated with nerve injury. The nerve was visualized during index surgery in 15 patients, with 4 transections. Multiple nerve injuries (n = 6) were most common around the distal humerus: 41.7% (5/12). The radial nerve comprised 52.9% (n = 9) of injuries in the distal humerus and 62.5% (n = 10) in the shaft with spontaneous recovery occurring in 75% (6/8) with distal fractures and 66.7% (6/9) with shaft fractures. The ulnar nerve accounted for 35.3% (n = 6) of injuries in the distal humerus and 25% (n = 4) in the shaft. Spontaneous recovery occurred in 60% (3/5) of ulnar nerve injuries around distal fractures but in only 25% (1/4) in the shaft. Half of ulnar nerve injuries were associated with additional nerve or vascular injury. The median nerve was the least likely to be injured: 40% (n = 2) distal humerus, 40% (n = 2) shaft, and 20% (n = 1) proximal humerus and 40% (2/5) spontaneously recovered.

CONCLUSION

In the setting of ballistic humerus fractures, arterial injury and bone loss were significantly associated with nerve injury. Multiple nerve injury occurred most commonly at the distal humerus. There was a 60-75% recovery rate of most nerve injuries however, ulnar nerve injuries around the shaft and median nerve injuries had lower rates of recovery.

LEVEL OF EVIDENCE

Level III.

Contribution of ultrasound in the management of ballistic nerve injury during the 2020 Nagorno-Karabakh war

PURPOSE

To evaluate the contribution of ultrasound in the management of ballistic peripheral nerve injuries (BPNI).

METHODS

Twenty-five Armenian soldiers who sustained BPNI of 44 different nerves during the Second Nagorno-Karabakh War in 2020 benefited from multidisciplinary team management including ultrasound examination.

RESULTS

The injuries affected the upper limb in 17 cases (including 2 bilateral cases), the lower limb in 7 cases and both upper and lower limb in 1 case. The injuries were due to shrapnel in 14 cases and to high-velocity bullets in 10 cases. One median-radial nerve injury occurred after prolonged haemostatic tourniquet. Thirteen patients had at least 2 nerves injuries. Ultrasound showed 16 nerves with neurapraxia, including 2 blast injuries, 8 axonotmesis with a neuroma-in-continuity and 8 neurotmesis. Twelve soldiers got surgery prior to our missions. The preoperative skin marking of nerve lesions under ultrasound control was very useful for the surgeon during the operation. A good correlation with surgery was observed, in 7 cases, and in 10 cases, a correlation with electroneuromyography (ENMG) was found. The ultrasound exploration was not informative in 2 patients.

CONCLUSION

Ultrasound is a useful examination for the assessment of BPNI. It allows exploration of the entire nerve without artefact in the presence of projectiles or external fixator, contrary to MRI. It localizes and characterizes the nerve damage with a good correlation with data from the surgery and ENMG.

CLINICAL RELEVANCE STATEMENT

Ballistic wounds of peripheral nerves are frequent in war wounded. Ultrasound can localize and characterize nerve injuries with good correlation with surgical and electrophysiological data.

Management of combat-related extremity injuries in modern armed conflicts

While the first conflicts of the 21st century involved asymmetric warfare in the fight against terrorism, recent geopolitical events require us to prepare for the possibility of high-intensity conflicts. Modern wounding agents mainly consist of explosive devices and high-velocity bullets. Every trauma surgeon must be familiar with the mechanisms of injury specific to armed conflicts. The initial care of these injuries is based on applying damage control surgery to save the patient's life, save their limb if possible and preserve their function. Blast injuries are the most common in modern armed conflicts; the resulting combination of severe injuries can be challenging to treat. Limb reconstruction involves a sequential strategy based on simple, reliable and reproducible techniques which can be used by non-specialized surgeons working in sometimes austere situations. LEVEL OF EVIDENCE: Expert opinion.

Low-Velocity Ballistic Trauma-Related Upper Extremity Nerve Injury: A Systematic Review and Meta-Analysis

PURPOSE

Optimal management of upper extremity nerve palsy caused by low-velocity ballistic trauma (LBT) remains controversial. The aim of this systematic review was to summarize the available evidence on the management of nerve injuries caused by LBT to the upper extremity.

METHODS

A literature search was completed for the keywords "Upper extremity," "Nerve Injury," and "Ballistic." 2 independent reviewers conducted a systematic screening of all articles and collected data from relevant publications. The data were summarized and pooled using a random-effect model.

RESULTS

14 studies met inclusion criteria. Cohorts between 6 and 168 patients (n = 848) with upper extremity LBT were reported. Neurologic deficits were present in 45% (95% CI: 38 to 52%) of patients at the time of injury evaluation. Nerve exploration was done in 50% (95% CI: 27 to 73%) of these patients with neurologic deficits. Early nerve exploration was done in 19% (95% CI: 9 to 32%) of all patients. Surgical findings included nerve continuity (49%; 95% CI: 14 to 84%), nerve contusion (30%; 95% CI: 12 to 50%), and nerve transection (31%; 95% CI: 14 to 50%). Nerve transection rates found at the time of exploration ranged from 0 to 71% (mean 31%). Outcomes were good in 62% (95% CI: 41 to 81%); however, analyses were limited by subjective outcome reporting of the studies.

CONCLUSIONS

Contrary to historical teaching that LBT causes neurapraxia, this review identified that 31% of resulting nerve injuries were neurotmesis (transections). These results advocate for systematic clinical follow-up and appropriately timed nerve intervention (within 3 to 6 months of injury) when neurologic deficits persist after ballistic injury.

LEVEL OF EVIDENCE

Level III.

Direct Suturing of Ulnar or Median Nerve Defects in High-Degree Elbow Flexion: An Experimental Cadaver Study

OBJECTIVE

The aim of this study is to determine the maximum loss of median and ulnar nerve substances that can be treated by direct suture in elbow flexion and to quantify this elbow flexion. The other objective is to determine the participation of the wrist position in this direct suture in elbow flexion.

METHODS

We performed an experimental study on 6 ulnar nerve lesions and 6 median nerve lesions. For each defect, a direct tensionless suture was performed with elbow flexion and in three different positions of the wrist (wrist extension, neutral position, and wrist flexion).

RESULTS

A 90° elbow flexion allowed direct suturing of defects up to 40 mm in the 3 positions of the wrist. A bowstringing effect (i.e., increase of the perpendicular distance of the nerve from the axis of rotation of the elbow) was noted starting from 25 mm of nerve defect. Wrist extension placed tension on the nerve suture for both nerves.

CONCLUSIONS

The results of this first anatomical study clarified the conditions for direct suturing of ulnar and median nerve defects in the flexed elbow position and flexed wrist position. This is an approach to consider for limited nerve defects to the elbow or when allograft harvesting is to be avoided.

Ballistic Nerve Injuries: State of the Evidence and Approach to the Patient Based on Experience

Nerve injuries secondary to gunshot wounds (GSWs) have been traditionally thought of as neurapraxic injuries with high likelihood of complete recovery. A review of the literature, however, highlights the misconceptions surrounding ballistic nerve injuries and their treatments. Contrary to this accepted dogma, approximately 30% to 60% of GSWs to the upper extremity may result in nerve injury requiring repair or reconstruction. Surgical exploration following ballistic injury reveals that 20% to 55% of nerves were lacerated requiring repair or grafting. Despite these numbers, outcomes after nerve repair or grafting are limited, and the limited data show evidence of poor functional recovery. In our experience, delayed exploration of GSW-related nerve injuries in patients without signs of functional recovery demonstrate large neuromas in continuity often requiring meticulous dissection and excision with resulting large gaps that require reconstruction. This has led us to explore options to identify patients with nerve deficits after GSWs who may benefit from earlier exploration. Others advocate for the exploration of all ballistic nerve injuries, which would represent a logistical challenge in high volume centers and may lead to unnecessary explorations of in continuity nerves. To facilitate identification of nerve injury following GSWs, we have explored the utilization of early ultrasound to identify patients with nerve lacerations that may benefit from early exploration (1-2 weeks after injury). Earlier exploration can lead to less technically challenging surgery, shorter nerve gaps, and more time for the nerve to recover. Herein, we present a series of cases to help illustrate this approach to the patient. Although early exploration and repair versus grafting of nerves may have benefits as outlined above, there are little to no data on outcomes of nerve repair or grafting in ballistic injuries in the more acute setting, 1 to 2 weeks after injury. Further research is needed both with regards to diagnosis and utilization of ultrasound, as well as postoperative outcomes in patients with ballistic nerve injuries to help guide our ever-evolving treatment protocols.

Treatment of Brachial Plexus Injuries following Gunshot Injuries: A Systematic Review

Introduction

Brachial plexus injuries (BPI) from gunshot injuries are uncommon but usually severe and can cause chronic pain, loss of function, and permanent nerve damage. Multiple surgical techniques including neurolysis, end-to-end suture repair, and graft repair have been described for the treatment of these injuries. However, surgical indication, timing, and technique for these injuries remain controversial. This systematic review aims to investigate the treatment modalities for patients with BPI due to gunshot-related injuries.

Methods

The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) methodology was employed for this review. PubMed, Cochrane Reviews, Embase, and CINAHL databases were included. The following keywords constituted our search criteria: gun-shot-wounds, brachial plexus, traum∗, and management.

Results

A total of 90 studies were imported for screening, from which 9 papers met our final inclusion/exclusion criteria. The most common studies utilized in this review were retrospective chart reviews followed by case series. In total, there were 628 patients that suffered from gunshot wounds to the brachial plexus. Most patients underwent some form of delayed nerve repair consisting of neurolysis, end-to-end epineural repair, or graft repair with a sural or antebrachial cutaneous nerve graft. Several patients suffered from complications, with neuroma being the most common long-term complication that required reoperation.

Conclusion

The optimal timing for surgeries involving BPIs should be determined after examining the level of nerve damage, associated injuries, operative risks, and electrophysiological workup for indications of spontaneous regeneration. Early surgical interventions were indicated for patients presenting with associated vascular or thoracic injuries, compressive masses, and nerve transection by sharp instruments in most selected papers.

Upper Extremity Ballistic Nerve Injury: A Scoping Review and Algorithm for Management

» Gunshot injuries to the upper extremity (UE) have high likelihood for causing peripheral nerve injury secondary to the high density of vital structures. Roughly one-fourth of patients sustaining a gunshot wound (GSW) to the UE incur a nerve injury. Of these nerve injuries, just over half are neurapraxic. In cases of surgical exploration of UE nerve injuries, nearly one-third demonstrate a transected or discontinuous nerve.» Existing literature regarding surgical management of nerve injuries secondary to GSWs comes from both military and civilian injuries. Outcomes are inconsistently reported, and indications are heterogeneous; however, reasonable results can be obtained with nerve reconstruction.» Our proposed management algorithm hinges on 4 treatment questions: if there is a nerve deficit present on examination, if there is a concomitant injury in the extremity (i.e., fracture or vascular insult), whether the injured nerve would be in the operative field of the concomitant injury, and whether there was an identified nerve lesion encountered at the time of surgery by another surgeon?» Early exploration rather than continued expectant management may offer improved recovery from GSW nerve injuries in particular situations. When an UE nerve deficit is present, establishing follow-up after the initial GSW encounter and early referral to a peripheral nerve surgeon are pivotal.

Neuroma-in-continuity: a review of pathophysiology and approach to the affected patient

A neuroma-in-continuity is a neuroma resulting from a nerve injury in which internal neuronal elements are partially disrupted (with a variable degree of disruption to the endoneurium and perineurium) while the epineurium typically remains intact. The portion of injured axons are misdirected and embedded in connective tissue, which may give rise to local neuroma pain and a distal nerve deficit. The lesion may result from a multitude of injury mechanisms, and clinical presentation is often variable depending on the nerve affected. Clinical, electrodiagnostic, and imaging examinations are helpful in assessing the extent and degree of the lesion. If no clear evidence of recovery is identified within 3-4 months post-injury, the patient may benefit from operative exploration. Surgical management options include neurolysis, neuroma resection, nerve grafting, and nerve transfer, or a combination of modalities. A primary consideration of surgery is the possibility of further downgrading nerve function in the pursuit of more, thereby highlighting the need to carefully weigh the advantages and disadvantages prior to surgical intervention. The objective of this review article is to describe the current understanding of the pathophysiology of neuroma-in-continuity lesions, and to review the approach to the affected patient including clinical evaluation, ancillary testing, and intraoperative assessment and treatment options.

Treatment of upper extremity nerve defects by direct suturing in high elbow or wrist flexion

PURPOSE

To evaluate functional outcomes after direct suturing of upper extremity nerve defects in high elbow or wrist flexion.

METHODS

A retrospective review was conducted in patients treated for median, ulnar, or radial nerve defects between 2011 and 2019. Inclusion criteria were a defect > 1 cm and a minimal follow-up period of 1 year. Nerve defects were bridged by an end-to-end suture in 90° elbow flexion or 70° wrist flexion for 6 weeks.

RESULTS

Nine patients with a mean age of 30.2 years were included. The patients presented with two ulnar nerve defects, four median nerve defects, and three radial nerve defects at various levels. The mean time to surgery was 13.5 weeks for recent injuries. The mean defect length was 2.9 cm, and the mean follow-up time was 22.4 months. Two patients had joint stiffness that was more likely related to the associated injuries than the 6-week immobilization. Successful outcomes were achieved in eight of the nine patients. Meaningful motor recovery was observed in seven patients, and all recovered meaningful sensation. Excellent nerve recovery was noted in pediatric patients and in those with distal nerve defects.

CONCLUSION

Temporary high joint flexion allows for direct coaptation of upper extremity nerve defects up to 4 cm located near the elbow or wrist. In this small and heterogenous cohort, functional outcomes seemed to be comparable to those obtained with short autografting.