Abstract
Background:
Understanding the clinical presentation of nontransected nerve injuries in acute hand trauma/wrist trauma will help in early intervention, which is vital for maximizing return of function in patients. This retrospective study evaluated patients who experienced traumatic hand injuries with nerve in continuity within the zone of injury.
Methods:
This was a single-center retrospective chart review of 20 patients with hand or wrist trauma resulting in damage to bone, tendon, or soft tissues within Zones II to V. Patients were 18 to 70 years of age and had documented visualization of at least one nerve within the zone of injury at the time of surgery but no documented full or partial nerve transection. The cohort was characterized using descriptive statistics including mechanism of injury, extent of strength and sensation deficits, and outcomes. Resolution of symptoms was defined as full, partial, or none.
Results:
Of the 20 patients included in the study, 15 patients (75%) showed symptoms of impaired nerve function either prior to surgery or at the first post-surgical follow-up visit. Without direct nerve treatment, only 23% (3/13) of patients experienced full recovery based on qualitative sensory assessment. However, patients reporting pain after surgery (57%; 8/14) showed full recovery from pain despite no direct nerve treatment.
Conclusions:
In our retrospective cohort of patients with hand/wrist trauma that presented with an intact nerve in continuity, we found that a majority showed symptoms of nerve injury. Further, these patients showed slow recovery over time with a minority achieving partial or full recovery or improvement in pain.
Keywords: trauma, diagnosis, hand, fracture/dislocation, nerve injury, nerve, anatomy, outcomes, research & health outcomes
Introduction
Hand trauma accounts for most upper extremity injuries and represents 5% to 10% of emergency department visits nationwide. 1 These injuries can take many forms, such as lacerations, fractures, crush, complex wounds, infections, and can cause osseous, soft tissue, neurologic, and/or vascular complications. 2 With potential variations in the mechanism, severity, and the tissues involved, these can be challenging cases to treat. The heterogeneous nature of these injuries makes each case unique, and treatment must be personalized to achieve the best possible outcome. Increased understanding and improved standard of care have helped in achieving favorable outcomes as they pertain to other tissue types; however, peripheral nerve injuries (PNIs) continue to be poorly understood. The incidence of PNI is often underestimated, and a lack of extensive clinical case series in the published literature remains a major limitation. 3 One estimate suggests 2% to 3% of all trauma patients have PNI. 4 Even though these injuries are rarely life-threatening, they can cause significant disability, threatening a patient’s livelihood and lifestyle.
Depending on the mechanism of injury, the nerve may be transected, stretched, or contused resulting in a lacerated nerve, neuroma, or neuroma in continuity. 4 Transected or partially transected nerves are often treated surgically with direct repair or with graft utilization.5-9 Furthermore, nontransected nerves, or nerve injuries in continuity, may present with obvious neurological deficit in strength and sensation.6-8,10,11 However, they are often dismissed intraoperatively or undergo further observation post-operatively if there is no obvious anatomical injury. These injured nerves in continuity present a surgical dilemma because of the lack of obvious repair needed.6-8,12 Additionally, as surrounding tissues begin to heal, the formation of scar tissue, reactive swelling, and edema may create a potentially hostile environment for recovery in otherwise healthy-looking nerves in continuity.
If left untreated, injured nerves may lead to persistent pain in addition to permanent motor or sensory deficit.13,14 Moreover, early intervention prior to edema and scar tissue formation may allow for easier exploration and treatment opportunities. 14 Though studies have looked at visually and anatomically evident injuries affecting the upper extremity peripheral nerves and the benefit of surgical management, there are few manuscripts describing risk factors and outcomes for nerves in continuity following significant upper extremity injury.5-8
In this retrospective, descriptive study, patients who experienced traumatic hand injuries and had nerves in continuity within the zone of injury were studied. The cohort was characterized based on mechanism of injury, extent of nerve deficiency in both strength and sensation, and relevant outcomes. An understanding of the potential for nontransected nerve injuries in acute hand trauma/wrist trauma will help in early identification and intervention, which is vital for maximizing the return of function in these types of patients.
Materials and Methods
In this single-center retrospective chart review performed at Vanderbilt University Medical Center, we identified patients who sustained hand or wrist trauma resulting in damage to bone or tendon and soft tissues within Zone II to Zone V between January 1, 2012, and December 31, 2017. All eligible patients were between 18 and 70 years of age and had documented exposure and visualization of at least one nerve within the zone of injury at the time of surgery but with no documented full or partial nerve transection.
Relevant outcomes included symptomatic postoperative nerve involvement, which was defined as any of the following: Sensory two-point discrimination (S2PD) more than 6 mm or a subjective appraisal of sensation reported by the patients charted as no sensation, or decreased/diminished sensation. Resolution of these symptoms was categorized as either full, partial or none. Full recovery was defined as intact sensation at the last follow-up visit where data were available and partial recovery was defined as an improvement in qualitative sensory assessment but not intact sensation. For pain, full recovery was defined as a pain value of 0 at the last follow-up visit where data were available. Patients with extensive soft tissue injury or vascular damage that impaired recovery assessment, cases where surgical intervention occurred 21 days post initial injury, and patients with type 1 and type 2 diabetes mellitus requiring regular insulin therapy were excluded from the analysis. Furthermore, patients who received chemotherapy, radiation therapy, or other treatment or medication that is known to affect the neural and/or vascular system were also excluded from the analysis. No patients reported prior neurological impairments or symptoms prior to injury. To ascertain more details, a chart review of all eligible patients was performed, and captured data was maintained in a Vanderbilt REDCap database. Clinical variables collected in the database included subject demographics, injury history, surgical intervention data, follow-up assessments, and economic data.
Based on the inclusion criteria, 50 patients were identified who underwent surgical repair of bone, tendon, or skin following acute traumatic injury to the hand or wrist. Of the 50 patients, a subgroup of 20 patients were reported to have nerves in continuity within the zone of injury and were included in this analysis (Table 1). Nerves in continuity were further characterized either as normal appearing nerves (n = 16) or nontransected nerve injury (ie, nerves with visible signs of injury such as edema, swelling, and/or bruising; n = 4). Symptoms that developed after surgery were tracked which included pain and sensation. The time to presentation for these symptoms was documented. These symptoms were then followed over time to investigate for complete or partial resolution. The mechanisms of injury were categorized and included lacerations (saw or sharp), firearm or blast, machinery/crush/compression injuries, or motor vehicle collisions. All patients received surgical intervention within 2 days of injury.
Table 1.
Injury Characteristics and Nerve Assessments.
| Subject # | Gender | Side | Zone(s) of injury | Mechanism of injury | Nerve classification | Nerve involvement? | ||
|---|---|---|---|---|---|---|---|---|
| Qualitative sensory assessment | S2PD | Presence of abnormal neurological symptoms | ||||||
| 1 | Male | Left | II | Saw laceration | Normal appearing | Yes | Yes | Yes |
| 2 | Male | Left | II | Firearm/blast | Normal appearing | Yes | Yes | Yes |
| 3 | Male | Right | III | Machinery/crush/compression | Normal appearing | Yes | — | Yes |
| 4 | Male | Left | II, III, V | Machinery/crush/compression | Nontransected nerve injury | Yes | Yes | Yes |
| 5 | Male | Right | II | Firearm/blast | Normal appearing | Yes | Yes | Yes |
| 6 | Female | Left | II | Machinery/crush/compression | Normal appearing | Yes | Yes | Yes |
| 8 | Female | Right | II, III | Motor vehicle collision | Normal appearing | — | — | No |
| 9 | Male | Right | V | Motor vehicle collision | Normal appearing | No | — | No |
| 10 | Male | Left | V | Saw laceration | Normal appearing | — | — | No |
| 11 | Male | Left | V | Saw laceration | Normal appearing | Yes | — | Yes |
| 15 | Male | Left | II, III | Firearm/blast | Nontransected nerve injury | Yes | Yes | Yes |
| 19 | Male | Left | II, V | Sharp laceration | Nontransected nerve injury | Yes | UNK | Yes |
| 20 | Male | Left | V | Sharp laceration | Nontransected nerve injury | Yes | — | Yes |
| 41 | Male | Left | III | Saw laceration | Normal appearing | Yes | Yes | Yes |
| 43 | Male | Left | III | Motor vehicle collision | Normal appearing | Yes | — | Yes |
| 44 | Male | Right | II | Sharp laceration | Normal appearing | No | — | No |
| 48 | Male | Right | V | Sharp laceration | Normal appearing | Yes | No | Yes |
| 49 | Female | Right | III | Motor vehicle collision | Normal appearing | Yes | Yes | Yes |
| 50 | Male | Left | II | Firearm/blast | Normal appearing | Yes | — | Yes |
| 51 | Male | Right, Left | II, III, IV | Motor vehicle collision | Normal appearing | No | — | No |
Note. S2PD = Sensory two-point discrimination; UNK = Unknown values.
Statistical Analysis
Data were evaluated and analyzed for incidence, recovery outcomes, and complications. All summaries of categorical data are presented in frequencies and percentages. All summaries of continuous data are presented by the number of nonmissing values, mean, standard deviation, standard error, median, minimum, maximum, and coefficient of variation.
Results
Twenty patients were included in this study. Of these, 15/20 (75%) had symptoms of impaired nerve function either prior to surgery or at the first post-surgical follow-up visit, presenting as subjective loss of intact sensation, higher scores on the S2PD, or pain greater than 1 on a 10-point scale. Notably, all patients, (4/4) in the nontransected nerve injury group had signs of impaired nerve function and 11/16 (68.75%) patients in the normal appearing nerve group had symptoms of neurological deficiency. Zone II injuries had a 73% likelihood of nerve involvement (8/11), Zone III had an 75% likelihood (6/8), Zone IV 0% (0/1), and Zone V 71% (5/7). Notably, some patients had injuries spanning more than one zone.
Recovery
Tables 2-4 demonstrate the symptoms reported by each of the 15 patients that presented with symptoms of possible impaired nerve function, and time to full resolution of symptoms for subjects who achieved it. Notably, two patients who presented with diminished sensation at the time of surgery did not have any subsequent information regarding sensation throughout the course of follow-up, so no determination of recovery could be made in those subjects, resulting in 13 subjects with recovery data for sensation. In the absence of direct nerve treatment, only 23% (3/13) of patients experienced full recovery based on qualitative sensory assessment. Furthermore, the patients who experienced full recovery were all noted to have normal appearing nerves. The majority, 77% (10/13), of patients either did not show any improvement (46%; 6/13) or experienced only partial recovery (31%; 4/13) in the sensory outcomes assessed at the last follow-up visit. When comparing normal appearing nerves to nontransected nerve injuries, there were no notable differences in partial recovery. Of the patients showing no improvement, there was a higher percentage of patients with nontransected nerve injuries (67%, 2/3) compared to 40% (4/10) of patients with normal appearing nerve.
Table 2.
Recovery of Nerve Function.
| Subject # | Nerve classification | Symptom | Full recovery | Partial recovery | No recovery |
|---|---|---|---|---|---|
| 1 | Normal | Sensation | ✓ | ||
| Pain | ✓ | ||||
| 2 | Normal | Sensation | UNK | UNK | UNK |
| Pain | ✓ | ||||
| 3 | Normal | Sensation | ✓ | ||
| Pain | ✓ | ||||
| 4 | Nontransected nerve injury | Sensation | UNK | UNK | UNK |
| Pain | ✓ | ||||
| 5 | Normal | Sensation | ✓ | ||
| Pain | ✓ | ||||
| 6 | Normal | Sensation | ✓ | ||
| Pain | ✓ | ||||
| 11 | Normal | Sensation | ✓ | ||
| Pain | ✓ | ||||
| 15 | Nontransected nerve injury | Sensation | ✓ | ||
| Pain | ✓ | ||||
| 19 | Nontransected nerve injury | Sensation | ✓ | ||
| Pain | ✓ | ||||
| 20 | Nontransected nerve injury | Sensation | ✓ | ||
| Pain | ✓ | ||||
| 41 | Normal | Sensation | ✓ | ||
| Pain | ✓ | ||||
| 43 | Normal | Sensation | ✓ | ||
| Pain | ✓ | ||||
| 48 | Normal | Sensation | ✓ | ||
| Pain | UNK | UNK | UNK | ||
| 49 | Normal | Sensation | ✓ | ||
| Pain | ✓ | ||||
| 50 | Normal | Sensation | ✓ | ||
| Pain | ✓ |
Note. UNK = Unknown values.
Table 3.
Summary of Nerve Function Recovery by Group.
| Nerve classification | Symptom | Full recovery (n/group N; %) | Partial recovery (n/group N; %) |
No recovery (n/group N; %) |
|---|---|---|---|---|
| Normal | Sensation | 3/10; 30 | 3/10; 30 | 4/10; 40 |
| Pain | 6/9; 67 | 2/9; 22 | 1/9; 11 | |
| Nontransected nerve injury | Sensation | 0/3; 0 | 1/3; 33 | 2/3; 67 |
| Pain | 1/4; 25 | 1/4; 25 | 2/4; 50 | |
| Total nerves | Sensation | 3/13; 23 | 4/13; 31 | 6/13; 46 |
| Pain | 8/14; 57 | 3/14; 21 | 3/14; 21 |
Table 4.
Duration to Full Recovery.
| Subject # | Time to resolution: pain (days) | Time to resolution: sensation (days) |
|---|---|---|
| 1 | 37 | — |
| 2 | 109 | — |
| 3 | 207 | — |
| 4 | 118 | — |
| 5 | — | 166 |
| 6 | 319 | 180 |
| 11 | 34 | — |
| 15 | 181 | — |
| 41 | 69 | — |
| 49 | 7 | 28 |
| Avg. (Stdev) | 120.1 (100.4) | 124.7 (84) |
On the other hand, most patients who reported pain after surgery (57%; 8/14) showed full recovery from pain (pain score of zero) despite no direct nerve treatment. Of these patients, 6 were patients with normal appearing nerve (6/9, 67%), and 1 patient had a non-transected nerve injury (1/4, 25%). However, 43% (6/14) of patients showed either only partial or no recovery from baseline pain scores. One patient did not have any pain reported throughout follow-up. When comparing normal appearing nerves to non-transected nerve injuries, there were no notable differences in partial recovery. Of the patients showing no improvement, there was a higher percentage of patients with nontransected nerve injuries (50%, 2/4) compared to 11% (1/9) of patients with normal appearing nerve.
Injury Type and Concomitant Injuries
In addition to assessing the presence or absence of nerve involvement and the incidence of recovery, we also sought to determine if certain injury types or concomitant tissue injuries had a higher likelihood of nerve involvement even when the nerve appears normal. Table 5 shows the distribution of patients that had damage to surrounding structures and concomitant nerve involvement, but where the nerve was assumed to be normal.
Table 5.
Incidence of Concomitant Injuries Associated With Nerve Involvement.
| Injury type | # of subjects with injury type | # of subjects with abnormal nerve symptoms |
|---|---|---|
| Fracture | 15/16 (93.75%) | 10/15 (66.67%) |
| Tendon | 11/16 (68.75%) | 9/11 (81.8%) |
| Ligament | 6/16 (37.5%) | 5/6 (83.3%) |
| Dislocation | 6/16 (37.5%) | 3/6 (50%) |
| Muscle | 4/16 (25%) | 2/4 (50%) |
| Vascular | 1/16 (6.25%) | 1/1 (100%) |
| Other | 1/16 (6.25%) | 0/1 (0%) |
Note. Incidence of concomitant injuries associated with nerve involvement.
Despite most patients having fractures, these only had a 67% frequency of having concomitant nerve involvement. Conversely, having a tendinous or ligamentous injury was correlated with a higher likelihood of nerve involvement (81.8% and 83.3%, respectively).
Mechanism of Injury
Table 6 displays the proportion of nerve involvement per mechanism of injury for the cohort of patients who had normal appearing nerve. All patients who experienced either a Firearm/Blast (3) or Machinery/Crush/Compression injury (2) also demonstrated one or more symptoms associated with possible nerve involvement. Similarly, 75% (3/4) of patients with a saw laceration demonstrated symptoms of nerve deficit. Only one-third of patients (2/6) who were injured in motor vehicle collisions had a possible nerve deficit associated with their injuries.
Table 6.
Mechanism of Injury.
| Mechanism of injury | # of subjects with injury type | # of subjects with nerve involvement |
|---|---|---|
| Motor vehicle collision | 5/16 (31.25%) | 2/5 (40%) |
| Saw laceration | 4/16 (25%) | 3/4 (75%) |
| Firearm/blast | 3/16 (18.75%) | 3/3 (100%) |
| Machinery/crush/compression | 2/16 (12.5%) | 2/2 (100%) |
| Sharp laceration | 2/16 (12.5%) | 1/2 (50%) |
Discussion
There are two main classification systems of nerve injuries that were developed by Seddon 15 and Sunderland. 16 The Seddon 15 system characterizes nerve injury as neuropraxia (demyelination), axonotmesis (discontinuity of axons), and neurotmesis (loss of continuity of the entire nerve). Sunderland 16 further elaborated on Seddon’s system segmenting axonotmesis into three different degrees, the first of which is discontinuity of axons only, the second is discontinuity of axons and endoneurial tubes, and the third is discontinuity of all structures except the epineurium. The neurotmetic or partial neurotmetic injuries are easily identified in the operating room. However, neuropraxic and axontometic injuries are much more difficult to identify and are what comprised the nerve injuries included in this study.
In our retrospective cohort of 20 patients with hand/wrist trauma that presented with either a normal appearing intact nerve, or an intact, but injured nerve, we found that 75% of patients with non-transected nerves within a zone of injury had signs and symptoms of nerve injury. Affirming our studies, Pannell et al, 11 looking at nerve injuries following gunshot wounds to the upper extremity found that 86% (12/14) of non-transected, contused nerves and 43% of intact nerves had palsy. Similarly, we found that 100% (4/4) of injured but continuous nerves had abnormal neurological symptoms and 69% (11/16) of “normal” nerves had signs and symptoms of nerve injury following trauma. These slight differences can be explained by the numbers within the cohort, comparison between a specific mechanism of action (GSW) and a mixed cohort of hand trauma, and different methods for analyzing nerve involvement. Furthermore, firearm and blast injuries as primary trauma were the most likely, along with crush or compression injuries, to result in nerve damage.
Trauma to surrounding structures near nerves not only reflects the energy and mechanism of the initial injury but may also indicate the likelihood of nerve involvement. For example, while most patients in our cohort had a fracture on presentation (94%), only 67% of these had concomitant symptoms of nerve injury. By contrast, ligamentous and tendinous injury, while less common, had a higher likelihood of abnormal neurological symptoms (>80%) potentially due to their anatomical locations adjacent to nerve. While pain related to multiple tissues within the injury site cannot be discounted, it may be that the type of injuries that result in trauma to the surrounding soft tissue may also affect the nerves through compression, heat, stretch, or contusion. While the source of pain is difficult to discern, it could be helpful for surgeons to be aware of these injury patterns when evaluating trauma patients for PNIs.
Recovery of function following hand trauma is of utmost importance. However, our results found surprisingly low recovery in both sensation and pain for nerves in continuity. Only 23% and 31% of patients had full or partial recovery, respectively, while a larger proportion (40%) had no improvement following surgery. A majority of patients (57%) did show full improvement in pain while 21% of patients showed partial improvement and 21% had no improvement in pain. These results reflect a sobering outcome for injured nerves in continuity following hand trauma. A full recovery of only 20% of patients with a functional deficit may indicate a need for further surgical care and alternative operative techniques and postoperative management for the care of these injuries from what is currently standard of care. Importantly, this study highlighted a lack of consistency in follow-up for these patients, particularly as it relates to functional outcomes, including validated neurological tests like the Semmes Weinstein monofilament (SWMF) and S2PD. For example, three patients were noted to have diminished sensation presenting after surgery. However, in each of these subjects, no tracking of improvement or change in subjective sensation was done after the initial note of reduced sensation. While these process measures point to a need for single institutional change it may also reflect a global need for more robust follow-up for these patients. Additionally, it was also surprising to find the lack of consistency of follow-up for these patients.
As a retrospective and descriptive study of 20 patients this study has important limitations to consider. First, at 20 patients, this constitutes a small cohort with variable mechanisms of injury and presentation. Second, the exact surgical treatment following trauma was not recorded, which would have allowed for further analysis. Finally, objective measurements of neurological deficit like the S2PD were not longitudinally tracked, which may highlight areas for further quality improvement in follow-up and areas of research opportunity.
Peripheral nerve injuries in upper extremity and hand trauma is a common presentation treated by orthopedic surgeons. However, despite the ubiquity of treatment for transected nerve injuries, there is scant data regarding injured nerves in continuity. These nerve injuries are often associated with deficits in sensation, strength, and pain, often needing a substantial amount of time to reach resolution. Mechanism of injury may also portend negative neurologic functional outcomes with blast or gunshot injury as well as crush or compression injuries resulting in a higher likelihood of problems with sensation. Similarly, surrounding soft tissue destruction, namely of ligaments and tendons, is more likely to result in nerve injury and functional deficits, highlighting the importance of considering injury patterns when evaluating for nerve injury. Finally, this study found a startlingly low proportion of patients who had functional recovery of their nerve deficits following hand trauma, obviating the need for further research, improved documentation and follow-up, and more focused management of nerves in continuity during hand trauma surgery. Further investigation into a larger patient cohort is planned, and may potentially provide further insight into the results of this study.
Acknowledgments
We would like to thank Dr. Andrew Raines and his team for project assistance and manuscript content review prior to submission.
Footnotes
Ethical Approval: This study was approved by our institutional review board.
Statement of Human and Animal Rights: This article does not contain any studies with animal and human subjects.
Statement of Informed Consent: This article does not include any identifying information, thus informed consent was not conducted.
The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: M. J. D. MD, is a Speaker’s Bureau Member for Axogen Inc. This study received financial and manuscript drafting support from Axogen Inc. D. E. P., MD has no conflicts to disclose.
Funding: The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Funding for data extraction was provided by Axogen inc.
ORCID iD: Daniel E. Pereira 
https://orcid.org/0000-0002-6356-9830
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