Median nerve injury and repair

Accessory head of flexor carpi radialis and abnormal course of the median nerve in the forearm

Background

The median nerve anatomy and its clinical presentation are crucial for surgeons to consider avoiding iatrogenic injury and performing effective surgical interventions.

Case Description

An atypical presentation of median nerve anatomy proximal to the carpal tunnel was found during cadaveric dissection. The median nerve was located deep to a uniquely double-headed flexor carpi radialis and curved medially around the tendons of the forearm to enter the carpal tunnel superficially.

Conclusion

The atypical presentation of median nerve anatomy can assist surgeons in adverse event reduction during surgeries such as carpal tunnel and pronator teres syndrome releases.

A review of 100 iatrogenic nerve injuries: delays in referrals remain significant

INTRODUCTION

This is a retrospective study of 100 consecutive patients with iatrogenic nerve injuries, as seen in a tertiary referral centre over a six-year period.

MATERIALS AND METHODS

Patients who presented with new-onset nerve palsy involving a motor or mixed motor/sensory nerve following an operation were studied.

RESULTS

There were 44 male and 56 female patients with a mean age of 53 years (range 5-87 years). The median duration from the index procedures to referral was six months (range 0 days to 12 years). Approximately one third of referrals were made over 12 months since the index procedures. Twenty patients recovered spontaneously and were managed expectantly. Eighty patients underwent secondary interventions.

DISCUSSION

There remains a significant delay in referring postoperative nerve palsy to a nerve specialist. The majority of these cases will warrant secondary reconstructive surgery and delay in treatment may have a negative effect on the ultimate outcomes.

Iatrogenic Nerve Injuries of the Upper Extremity: A Critical Analysis Review

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Iatrogenic nerve injuries may occur after any intervention of the upper extremity.

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Causes of iatrogenic nerve lesions include direct sharp or thermal injury, retraction, compression from implants or compartment syndrome, injection, patient positioning, radiation, and cast/splint application, among others.

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Optimal treatment of iatrogenic peripheral nerve lesions relies on early and accurate diagnosis.

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Advanced imaging modalities (e.g., ultrasound and magnetic resonance imaging) and electrodiagnostic studies aid and assist in preoperative planning.

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Optimal treatment of iatrogenic injuries is situation-dependent and depends on the feasibility of direct repair, grafting, and functional transfers.

Reversal of neuropathic pain is associated with corticostriatal functional reorganization after nerve repair in the spared nerve injury model

ABSTRACT

Following surgical repair after peripheral nerve injury, neuropathic pain diminishes in most patients but can persist in a small proportion of cases, the mechanism of which remains poorly understood. Based on the spared nerve injury (SNI), we developed a rat nerve repair (NR) model, where a delayed reconstruction of the SNI-injured nerves resulted in alleviating chronic pain-like behavior only in a subpopulation of rats. Multiple behavioral measures were assayed over 11-week presurgery and postsurgery periods (tactile allodynia, pain prick responses, sucrose preference, motor coordination, and cold allodynia) in SNI (n = 10), sham (n = 8), and NR (n = 12) rats. All rats also underwent resting-state functional magnetic resonance imaging under anesthesia at multiple time points postsurgery, and at 10 weeks, histology and retrograde labeling were used to calculate peripheral reinnervation. Behavioral measures indicated that at approximately 5 weeks postsurgery, the NR group separated to pain persisting (NR persisting, n = 5) and recovering (NR recovering, n = 7) groups. Counts of afferent nerves and dorsal root ganglion cells were not different between NR groups. Therefore, NR group differences could not be explained by peripheral reorganization. By contrast, large brain functional connectivity differences were observed between NR groups, where corticolimbic reorganization paralleled with pain recovery (repeated-measures analysis of variance, false discovery rate, P < 0.05), and functional connectivity between accumbens and medial frontal cortex was related both to tactile allodynia (nociception) and to sucrose preference (anhedonia) in the NR group. Our study highlights the importance of brain circuitry in the reversal of neuropathic pain as a natural pain-relieving mechanism. Further studies regarding the therapeutic potentials of these processes are warranted.

Treatment of painful median nerve neuroma using pedicled vascularized lateral antebrachial cutaneous nerve with adipofascial flap: a cadaveric study and exploration of clinical application

The most common procedure for the treatment of painful median nerve neuroma is coverage with vascularized soft tissue following external neurolysis. However, the ideal treatment should include reconnecting the proximal and distal stumps of the damaged nerve to allow the growth of regenerating axons to their proper targets for a functional recovery. We developed a useful technique employing radial artery perforator adipofascial flap including the lateral antebrachial cutaneous nerve (LABCN) to repair the median nerve by vascularized nerve grafting and to achieve coverage of the nerve with vascularized soft tissue. In an anatomical study of 10 fresh-frozen cadaver upper extremities, LABCN was constantly bifurcated into two branches at the proximal forearm (mean: 8.2 cm distal to the elbow) and two branches that run in a parallel manner toward the wrist. The mean length of the LABCN branches between the bifurcating point and the wrist was 18.2 cm, which enabled inclusion of adequate length of the LABCN branches into the radial artery perforator adipofascial flap. The diameters of the LABCN branches (mean: 1.7 mm) were considered suitable to bridge the funiculus of the median nerve defect after microsurgical internal neurolysis. In all cadaver upper extremities, the 3-cm median nerve defect at the wrist level could be repaired using the LABCN branches and covered with the radial artery perforator adipofascial flap. On the basis of this anatomical study, the median nerve neuroma was successfully treated with radial artery perforator adipofascial flap including vascularized LABCN branches.

Sensibility, Sensation, and Nerve Regeneration after Reconstructive Genital Surgery: Evolving Concepts in Neurobiology

BACKGROUND

Sensory recovery following phalloplasty and vaginoplasty for gender dysphoria is essential to the overall success of gender-confirming surgery. Anecdotal evidence suggests that superior reinnervation results are seen in genitoplasty compared to other peripheral nerve repair scenarios. Despite these observed differences, the quality of available literature is poor.

METHODS

The authors reviewed the body of English language literature regarding sensory outcomes following genitoplasty for gender confirmation.

RESULTS

The available body of literature discussing the basic science and clinical science aspects of sensory recovery following gender-confirming genitoplasty is small. Available data show that sensory recovery following vaginoplasty produces high rates of reported orgasmic ability, largely through the neoclitoris, and a neovagina with vibratory and pressure sensation similar to that of the native vagina. Phalloplasty sensory outcomes are variable, with the largest series reporting return of sensation in the neophallus that is slightly less than what is measured in control men. Erogenous sensation, including the ability to orgasm, is present in nearly all patients after several months.

CONCLUSIONS

Existing series indicate that genitoplasty patients experience faster and more complete recovery than any other peripheral nerve regeneration scenarios. However, there are many potential confounding factors in assessment and reporting, and more consistent and reproducible measure endpoints measures are needed. Further research is needed to better understand both the basic science and clinical science of peripheral nerve regeneration in genitoplasty, which may change fundamental aspects of current paradigms of peripheral nerve regeneration.

Surgical Treatment of Upper Extremity Gunshot Injures: An Updated Review

INTRODUCTION

Firearm morbidity and mortality have been increasing in recent years, and with this, the demand for medical personnel firearm injury treatment knowledge. Extremities contribute to a majority of firearm injuries, with these injuries being particularly complex because of neurovascular proximity within a confined space. Knowledge of firearm mechanism of injury and treatment management options is important for any trauma hand surgeon. Many factors play vital roles in the treatment of complex upper extremity (UE) gunshot wounds (GSWs). The aim of our review and case illustrations is to provide hand surgeons with an up-to-date guide for initial emergent management, soft tissue, bony, and nerve repair and reconstruction.

PATIENT AND METHODS

A literature review was conducted in the current management of UE GSW injuries, and 2 specific patient case examples were included. High-energy versus low-energy GSWs were documented and compared, as well as containment injures. Management including soft tissue, bony, and nerve injuries was explored along with patient outcome. Based on these findings, guidelines for GSW management were purposed.

CONCLUSION

Gunshot wounds of the UE encompass a group of highly heterogeneous injuries. High-energy wounds are more extensive, and concomitant injuries to bone, vessel, nerve, muscle, and soft tissue are common. Early treatment with adequate debridement, skeletal fixation, and soft tissue coverage is indicated for complex injuries, and antibiotic treatment in the pre-, peri-, and postoperative period is indicated for operative injuries. Soft tissue coverage options include the entire reconstructive ladder, with pattern of injury and considerations of wound characteristics dictating reconstructive choice. There are arguments to using either external or internal bony fixation techniques for bone fracture management, with choice tailored to the patient. For management of nerve injuries, we advocate earlier nerve repair and a shorter duration of observation before secondary reconstruction in selective cases. If transected nerve endings cannot be brought together, nerve autografts of shorter length are recommended to bridge nerve ending gaps. A significant number of patients with GSW fail to make necessary follow-up appointments, which adds to challenges in treatment.

Impaired Limb Functional Outcome of Peripheral Nerve Regeneration Is Marked by Incomplete Recovery of Paw Muscle Atrophy and Brain Functional Connectivity in a Rat Forearm Nerve Repair Model

Skilled sensorimotor deficit is an unsolved problem of peripheral nerve injury (PNI) led by limb trauma or malignancies, despite the improvements in surgical techniques of peripheral nerve anastomosis. It is now accepted that successful functional recovery of PNI relies tremendously on the multilevel neural plasticity from the muscle to the brain. However, animal models that recapitulate these processes are still lacking. In this report, we developed a rat model of PNI to longitudinally assess peripheral muscle reinnervation and brain functional reorganization using noninvasive imaging technology. Based on such model, we compared the longitudinal changes of the rat forepaw intrinsic muscle volume and the seed-based functional connectivity of the sensorimotor cortex after nerve repair. We found that the improvement of skilled limb function and the recovery of paw intrinsic muscle following nerve regeneration are incomplete, which correlated with the functional connectivity between the primary motor cortex and dorsal striatum. Our results were highly relevant to the clinical observations and provided a framework for future investigations that aim to study the peripheral central sensorimotor circuitry underlying skilled limb function recovery after PNI.

A Preligamentous Variant of the Thenar Motor Branch of the Median Nerve

We report a rare variant of the thenar motor branch (TMB) of the median nerve. A preligamentous TMB was discovered during revision carpal tunnel release in a 49-year-old man. The prevalence and characteristics of TMB variations are discussed. The literature describing iatrogenic injury to the TMB variants, surgical treatment, and preoperative screening tools is reviewed. Recognition of anatomic variants of the TMB is essential considering notable consequences of iatrogenic injury.

Disinhibition of Human Primary Somatosensory Cortex After Median Nerve Transection and Reinnervation

Despite state-of-the-art surgical and postoperative treatment, median nerve transection causes lasting impaired hand function due to limitations in the nerve’s reinnervation ability. The defective innervation and thus controllability of the affected hand can shape the brain’s control of manual behaviors. Earlier studies of changes in the processing of tactile stimuli have focused mainly on stimulation of the reinnervated hand and lack sufficient control over the brain’s use of the tactile input in perceptual terms. Here we used fMRI to measure brain activity (BOLD-signal) in 11 people with median nerve injury and healthy controls (N = 11) when performing demanding tactile tasks using the tip of either the index or little finger of either hand. For the nerve-injured group, the left median nerve had been traumatically transected in the distal forearm and surgically repaired on average 8 years before the study. The hand representation of their contralesional (right) primary somatosensory cortex (S1) showed greater activity compared to controls when the left reinnervated index finger was used, but also when the left-hand little finger and the fingers of the right hand innervated by uninjured nerves were used. We argue that the overall increase in activity reflects a general disinhibition of contralesional S1 consistent with an augmented functional reorganizational plasticity being an ongoing feature of chronic recovery from nerve injury. Also, the nerve-injured showed increased activity within three prefrontal cortical areas implicated in higher-level behavioral processing (dorsal anterior cingulate cortex, left ventrolateral prefrontal and right dorsolateral prefrontal cortex), suggesting that processes supporting decision-making and response-selection were computationally more demanding due to the compromised tactile sensibility.

Topical Application of Human Wharton's Jelly Mesenchymal Stem Cells Accelerates Mouse Sciatic Nerve Recovery and is Associated with Upregulated Neurotrophic Factor Expression

Peripheral nerve regeneration following injury is often slow and impaired, which results in weakened and denervated muscle with subsequent atrophy. Human Wharton's jelly mesenchymal stem cells (hWJ-MSC) have potential regenerative properties which, however, remain unknown in mouse nerve recovery. This study investigated the effect of the topical application of hWJ-MSC onto repairing transected sciatic nerves in a mouse model. Human adipocyte-derived stem cells (hADSC) were used as a positive control. The sciatic nerve of BALB/c mice was transected at a fixed point and repaired under the microscope using 10-0 sutures. hWJ-MSC and hADSC were applied to the site of repair and mice were followed up for 1 year. The hWJ-MSC group had significantly better functional recovery of five-toe spread and gait angles compared with the negative control and hADSC groups. hWJ-MSC improved sciatic nerve regeneration in a dose-dependent fashion. The hWJ-MSC group had a better quality of regenerated nerve with an increased number of myelinated axons throughout. hWJ-MSC appear to be safe in mice after 1 year of follow-up. hWJ-MSC also expressed higher levels of neurotrophic factor-3, brain-derived neurotrophic factor, and glial-derived neurotrophic factor than hADSC. hWJ-MSC may promote better nerve recovery than hADSC because of this upregulation of neurotrophic factors.

Management of Recalcitrant Carpal Tunnel Syndrome

Recalcitrant carpal tunnel syndrome presents a clinical challenge. Potential etiologies of persistent or recurrent symptoms after primary carpal tunnel release include incomplete nerve decompression, secondary sites of nerve compression, unrecognized anatomic variations, irreversible nerve pathology associated with chronic compression neuropathy, perineural adhesions, conditions associated with secondary nerve compression, iatrogenic nerve injury, or inaccurate preoperative diagnosis. Understanding the pertinent surgical anatomy and pathophysiology is essential toward developing an effective diagnostic and treatment strategy. A thorough clinical history and examination guide a comprehensive diagnostic evaluation that includes serial examinations, neurophysiologic testing, and imaging studies. Conservative treatment may provide symptomatic relief; however, surgical management involving revision neuroplasty, neurolysis, nerve reconstruction, and/or local soft-tissue flap augmentation may be indicated in refractory cases.

Pulsed radiofrequency of the median nerve under ultrasound guidance for management of intractable neuropathic pain

A median nerve injury in the forearm may lead to devastating sequelae if left untreated. Even with appropriate treatments involving microsurgical techniques and postoperative care, patients may still experience lasting neuropathic pain that significantly reduces their quality of life. Pulsed radiofrequency (PRF) is widely performed to alleviate such neuropathic pain caused by trauma.

A 47-year-old man visited our pain clinic with allodynia, hyperalgesia, paresthesia, skin color changes, and atrophy in the right forearm. In the orthopedic department, the patient was treated by neurectomy of the median nerve to manage the intractable pain. However, the effect was unsatisfactory. The fourth median nerve block performed in our pain clinic after neurectomy produced good results, and ultrasound-guided PRF of the median nerve was performed.

The patient showed 80% relief of symptoms within 5 hours after the procedure. The visual analog scale score for the forearm decreased from 8/10 to 1/10. This case suggests that ultrasound-guided PRF can be a therapeutic option for the management of refractory neuropathic pain after neurectomy in patients with a median nerve injury.

[Acute carpal tunnel syndrome regarding clinico-anatomical point of view in personified medicine]

Carpal tunnel syndrome (CTS) requires special attention due to its different reasons and course. Knowledge about the variability of median nerve (MN) topography in carpal canal region, features of diagnosis and treatment extends outlooks on this pathology. Aggregating rare clinical cases from the Medline and Pubmed databases is useful to form personified approach. There are 3 types of topographic variations which should be considered to prevent false-positive diagnosis of pathology: recurrent branch location, early bi- and trifurcations of MN, anastomoses. Since acute CTS is treated only by surgery, every surgical approach is aimed at minimally invasiveness and fast recovery. Endoscopic decompression (ED) is more favorable regarding these aspects. However, this method cannot be considered as perfect due to available data about incomplete decompression and certain incidence of recurrences. The last ones are absent after microsurgical decompression as a rule. It can be concluded that only individual approach is advisable for complete release of CTS without iatrogenic damage and recurrences.

Reinnervation of spinal cord anterior horn cells after median nerve repair using transposition with other nerves

Our previous studies have confirmed that during nerve transposition repair to injured peripheral nerves, the regenerated nerve fibers of motor neurons in the anterior horn of the spinal cord can effectively repair distal nerve and target muscle tissue and restore muscle motor function. To observe the effect of nerve regeneration and motor function recovery after several types of nerve transposition for median nerve defect (2 mm), 30 Sprague-Dawley rats were randomly divided into sham operation group, epineurial neurorrhaphy group, musculocutaneous nerve transposition group, medial pectoral nerve transposition group, and radial nerve muscular branch transposition group. Three months after nerve repair, the wrist flexion test was used to evaluate the recovery of wrist flexion after regeneration of median nerve in the affected limbs of rats. The number of myelinated nerve fibers, the thickness of myelin sheath, the diameter of axons and the cross-sectional area of axons in the proximal and distal segments of the repaired nerves were measured by osmic acid staining. The ratio of newly produced distal myelinated nerve fibers to the number of proximal myelinated nerve fibers was calculated. Wet weights of the flexor digitorum superficialis muscles were measured. Muscle fiber morphology was detected using hematoxylin-eosin staining. The cross-sectional area of muscle fibers was calculated to assess the recovery of muscles. Results showed that wrist flexion function was restored, and the nerve grew into the distal effector in all three nerve transposition groups and the epineurial neurorrhaphy group. There were differences in the number of myelinated nerve fibers in each group. The magnification of proximal to distal nerves was 1.80, 3.00, 2.50, and 3.12 in epineurial neurorrhaphy group, musculocutaneous nerve transposition group, medial pectoral nerve transposition group, and radial nerve muscular branch transposition group, respectively. Nevertheless, axon diameters of new nerve fibers, cross-sectional areas of axons, thicknesses of myelin sheath, wet weights of flexor digitorum superficialis muscle and cross-sectional areas of muscle fibers of all three groups of donor nerves from different anterior horn motor neurons after nerve transposition were similar to those in the epineurial neurorrhaphy group. Our findings indicate that donor nerve translocation from different anterior horn motor neurons can effectively repair the target organs innervated by the median nerve. The corresponding spinal anterior horn motor neurons obtain functional reinnervation and achieve some degree of motor function in the affected limbs.

A comparative study of rehabilitation therapy in traumatic upper limb peripheral nerve injuries

INTRODUCTION

Lower motor neurons are the only neurons of the central nervous system (CNS) with the ability to regenerate without any intervention after an axotomy.

AIM

This present study was conducted to analyze clinical and electrophysiological parameters in four groups of upper limb peripheral neuropathies, before and after treatment, comparing the results obtained after three cures of complex rehabilitation therapy.

MATERIALS AND METHODS

We selected a number of 107 patients (66 women and 41 men) aged between 29 and 77 years (mean age = 49.6). Clinical (muscular strength, sensitivity) and electrophysiological parameters (accommodation coefficient α, nerve conduction velocity) were analyzed. All patients received 3 comprehensive treatment cures, each cure of 14 days and a rest period of 3 months between the cures.

RESULTS

From the total of 107 patients included in the study, 52 were diagnosed with brachial plexus palsy, 27 with radial nerve palsy, 18 with median nerve palsy and 10 with ulnar nerve palsy. We did not observe a statistically significant difference between the mean age of males (47.2) and females (51.2) (p = 0.07), but peripheral neuropathies were more common in young males. At the end of the rehabilitation treatment all patients achieved better outcomes in muscle strength, sensitivity, adjustment coefficient α and nerve conduction velocity (p < 0.001).CONCLUSIONThe intervention of a physical therapy program in patients with peripheral neuropathies provided significantly better outcomes in clinical and electrophysiological parameters. Our rehabilitation protocol can be considered an alternative in order to stimulate and accelerate the nerve regeneration process.

Vascularized Nerve Bypass Graft: A Case Report of an Additional Treatment for Poor Sensory Recovery

End-to-side neurorrhaphy has proven effective in basic research and in clinical application. One of the methods of end-to-side neurorrhaphy, nerve bypass technique, has been reported and axon regeneration has been proven. In clinical application, the utility of the nerve bypass technique has been revealed in some cases; however, these bypasses were performed using nonvascularized nerves. We initially used the vascularized nerve bypass graft technique with the sural nerve as a secondary clinical procedure after median nerve injury in a 61-year-old patient and achieved motor and sensory nerve regeneration, as supported by a nerve conduction study and clinical sensory test. This technique has the potential to become one of the choices for salvage procedure of severe nerve injury.

Nerve Repair and Nerve Grafting

Direct repair and nerve autografting are primary options in the treatment of upper extremity peripheral nerve injuries. Deciding between these surgical options depends on the mechanism of injury, time since injury, and length of repair defect. Principles of direct repair and nerve autografting are reviewed. Finally, a literature-based review of the outcomes of upper extremity peripheral nerve repair and autografting is provided. Taken together, this article provides relevant and recent data for surgeons regarding patient selection, technique selection, surgical technique, surgical outcomes, and prognostic factors that will aid surgeons treating patients with upper extremity peripheral nerve injuries.

Sensory perturbations using suture and sutureless repair of transected median nerve in rats

The effects of changes to cold, mechanical, and heat thresholds following median nerve transection with repair by sutures (Su) or Rose Bengal adhesion (RA) were compared to sham-operated animals. Both nerve-injured groups showed a transient, ipsilateral hyposensitivity to mechanical and heat stimuli followed by a robust and long-lasting hypersensitivity (6-7 weeks) with gradual recovery towards pre-injury levels by 90 days post-repair. Both tactile and thermal hypersensitivity were seen in the contralateral limb that was similar in onset but differed in magnitude and resolved more rapidly compared to the injured limb. Prior to injury, no animals showed any signs of aversion to cold plate temperatures of 4-16 °C. After injury, animals showed cold allodynia, lasting for 7 weeks in RA-repaired rats before recovering towards pre-injury levels, but were still present at 12 weeks in Su-repaired rats. Additionally, sensory recovery in the RA group was faster compared to the Su group in all behavioural tests. Surprisingly, sham-operated rats showed similar bilateral behavioural changes to all sensory stimuli that were comparable in onset and magnitude to the nerve-injured groups but resolved more quickly compared to nerve-injured rats. These results suggest that nerve repair using a sutureless approach produces an accelerated recovery with reduced sensorimotor disturbances compared to direct suturing. They also describe, for the first time, that unilateral forelimb nerve injury produces mirror-image-like sensory perturbations in the contralateral limb, suggesting that the contralateral side is not a true control for sensory testing. The potential mechanisms involved in this altered behaviour are discussed.

Evidence-based Comprehensive Approach to Forearm Arterial Laceration

INTRODUCTION

Penetrating injury to the forearm may cause an isolated radial or ulnar artery injury, or a complex injury involving other structures including veins, tendons and nerves. The management of forearm laceration with arterial injury involves both operative and nonoperative strategies. An evolution in management has emerged especially at urban trauma centers, where the multidisciplinary resource of trauma and hand subspecialties may invoke controversy pertaining to the optimal management of such injuries. The objective of this review was to provide an evidence-based, systematic, operative and nonoperative approach to the management of isolated and complex forearm lacerations. A comprehensive search of MedLine, Cochrane Library, Embase and the National Guideline Clearinghouse did not yield evidence-based management guidelines for forearm arterial laceration injury. No professional or societal consensus guidelines or best practice guidelines exist to our knowledge.

DISCUSSION

The optimal methods for achieving hemostasis are by a combination approach utilizing direct digital pressure, temporary tourniquet pressure, compressive dressings followed by wound closure. While surgical hemostasis may provide an expedited route for control of hemorrhage, this aggressive approach is often not needed (with a few exceptions) to achieve hemostasis for most forearm lacerations. Conservative methods mentioned above will attain the same result. Further, routine emergent or urgent operative exploration of forearm laceration injuries are not warranted and not cost-beneficial. It has been widely accepted with ample evidence in the literature that neither injury to forearm artery, nerve or tendon requires immediate surgical repair. Attention should be directed instead to control of bleeding, and perform a complete physical examination of the hand to document the presence or absence of other associated injuries. Critical ischemia will require expeditious surgical restoration of arterial perfusion. In a well-perfused hand, however, the presence of one intact artery is adequate to sustain viability without long-term functional disability, provided the palmar arch circulation is intact. Early consultation with a hand specialist should be pursued, and follow-up arrangement made for delayed primary repair in cases of complex injury.

CONCLUSION

Management in accordance with well-established clinical principles will maximize treatment efficacy and functional outcome while minimizing the cost of medical care.