Supercharge End-to-Side Anterior Interosseous-to-Ulnar Motor Nerve Transfer Restores Intrinsic Function in Cubital Tunnel Syndrome

Supercharged end-to-side anterior interosseous nerve transfer to restore intrinsic function in high ulnar nerve injury: a prospective cohort study

BACKGROUND

High ulnar nerve injuries is known to have unfavorable motor outcomes compared to other peripheral nerve injuries in the upper extremity. Functional muscle recovery after peripheral nerve injury depends on the time to motor end plate reinnervation and the number of motor axons that successfully reach the target muscle. The purpose of this study is to assess the functional recovery, and complications following performing supercharge end-to-side (SETS) anastomosis for proximal ulnar nerve injuries. Our study focuses on the role of SETS in the recovery process of high ulnar nerve injury.

PATIENT AND METHODS

This study is a prospective, single-arm, open-label, case series. The original proximal nerve pathology was dealt with according to the cause of injury, then SETS was performed distally. The follow-up period was 18 months. We compared the neurological findings before and after the procedure. A new test was used to show the effect of SETS on recovery by performing a Lidocaine proximal ulnar nerve block test.

RESULTS

Recovery of the motor function of the ulnar nerve was evident in 33 (86.8%) patients. The mean time to intrinsic muscle recovery was 6.85 months ± 1.3, only 11.14% of patients restored protective sensation to the palm and finger and 86.8% showed sensory level at the wrist level at the end of the follow-up period. Lidocaine block test was performed on 35 recovered patients and showed no change in intrinsic hand function in 31 patients.

CONCLUSION

SETS exhibit a remarkable role in the treatment of high ulnar nerve damage. SETS transfer can act as a nerve transfer that can supply intrinsic muscles by its fibers and allows for proximal nerve regeneration. We believe that this technique improves recovery of hand motor function and allows recovery of sensory fibers when combined with treating the proximal lesion.

TRIAL REGISTRATION

Approved by Research Ethics Committee of Faculty of Medicine- Cairo University on 01/09/2021 with code number: MD-215-2021.

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.

Supercharge end-to-side nerve transfer from anterior interosseous nerve to augment intrinsic recovery in high ulnar nerve injuries of varying magnitudes

BACKGROUND

High ulnar nerve injuries result in intrinsic muscle weakness and are inconvenient for patients. Moreover, conventional surgical techniques often fail to achieve satisfactory motor recovery. A potential reconstructive solution in the form of the supercharge end-to-side (SETS) anterior interosseous nerve (AIN) transfer method has emerged. Therefore, this study aims to compare surgical outcomes of patients with transected and in-continuity high ulnar nerve lesions following SETS AIN transfer.

METHODS

Between June 2015 and May 2023, patients with high ulnar palsy in the form of transection injuries or lesion-in-continuity were recruited. The assessment encompassed several objective results, including grip strength, key pinch strength, compound muscle action potential, sensory nerve action potential, and two-point discrimination tests. The muscle power of finger abduction and adduction was also recorded. Additionally, subjective questionnaires were utilized to collect data on patient-reported outcomes. Overall, the patients were followed up for up to 2 years.

RESULTS

Patients with transected high ulnar nerve lesions exhibited worse baseline performance than those with lesion-in-continuity, including motor and sensory functions. However, they experienced greater motor improvement but less sensory recovery, resulting in comparable final motor outcomes in both groups. In contrast, the transection group showed worse sensory outcomes.

CONCLUSIONS

Our findings suggest that SETS AIN transfer benefits patients with high ulnar nerve palsy, regardless of the lesion type. Nonetheless, improvements may be more pronounced in patients with transected lesions.

A Systematic Review of Registered Clinical Trials for Peripheral Nerve Injuries

ABSTRACT

Upper extremity peripheral nerve injuries (PNIs) significantly impact daily functionality and necessitate effective treatment strategies. Clinical trials play a crucial role in developing these strategies. However, challenges like retrospective data collection, reporting biases, inconsistent outcome measures, and inadequate data sharing practices hinder effective research and treatment advancements. This review aims to analyze the landscape of reporting, methodological design, outcome measures, and data sharing practices in registered clinical trials concerning upper extremity PNIs. It seeks to guide future research in this vital area by identifying current trends and gaps.A systematic search was conducted on ClinicalTrials.gov and WHO International Clinical Trials Registry Platform up to November 10, 2023, using a combination of MeSH terms and keywords related to upper extremity nerve injury. The PRISMA 2020 guidelines were followed, and the studies were selected based on predefined inclusion and exclusion criteria. A narrative synthesis of findings was performed, with statistical analysis for associations and completion rates.Of 3051 identified studies, 96 met the inclusion criteria. These included 47 randomized controlled trials, 27 nonrandomized trials, and others. Sensory objective measures were the most common primary outcomes. Only 13 studies had a data sharing plan. The analysis revealed varied intervention methods and inconsistencies in outcome measures. There was a significant association between study funding, design, and completion status, but no association between enrollment numbers and completion.This review highlights the need for standardized outcome measures, patient-centered assessments, and improved data sharing in upper extremity PNI trials. The varied nature of interventions and inconsistency in outcome measures indicate the necessity for more rigorous and transparent research practices to strengthen the evidence base for managing these injuries.

The Unpredictable Ulnar Nerve-Ulnar Nerve Entrapment from Anatomical, Pathophysiological, and Biopsychosocial Aspects

Peripheral nerves consist of delicate structures, including a rich microvascular system, that protect and nourish axons and associated Schwann cells. Nerves are sensitive to internal and external trauma, such as compression and stretching. Ulnar nerve entrapment, the second most prevalent nerve entrapment disorder after carpal tunnel syndrome, appears frequently at the elbow. Although often idiopathic, known risk factors, including obesity, smoking, diabetes, and vibration exposure, occur. It exists in all adult ages (mean age 40-50 years), but seldom affects individuals in their adolescence or younger. The patient population is heterogeneous with great co-morbidity, including other nerve entrapment disorders. Typical early symptoms are paresthesia and numbness in the ulnar fingers, followed by decreased sensory function and muscle weakness. Pre- and postoperative neuropathic pain is relatively common, independent of other symptom severity, with a risk for serious consequences. A multimodal treatment strategy is necessary. Mild to moderate symptoms are usually treated conservatively, while surgery is an option when conservative treatment fails or in severe cases. The decision to perform surgery might be difficult, and the outcome is unpredictable with the risk of complications. There is no consensus on the choice of surgical method, but simple decompression is relatively effective with a lower complication rate than transposition.

Surgery for mononeuropathies

Advancement in microsurgical techniques and innovative approaches including greater use of nerve and tendon transfers have resulted in better peripheral nerve injury (PNI) surgical outcomes. Clinical evaluation of the patient and their injury factors along with a shift toward earlier time frame for intervention remain key. A better understanding of the pathophysiology and biology involved in PNI and specifically mononeuropathies along with advances in ultrasound and magnetic resonance imaging allow us, nowadays, to provide our patients with a logical and sophisticated approach. While functional outcomes are constantly being refined through different surgical techniques, basic scientific concepts are being advanced and translated to clinical practice on a continuous basis. Finally, a combination of nerve transfers and technological advances in nerve/brain and machine interfaces are expanding the scope of nerve surgery to help patients with amputations, spinal cord, and brain lesions.

Clinical Outcomes of Upper Extremity Nerve Transfers in Neuralgic Amyotrophy

SUMMARY

Neuralgic amyotrophy (NA) is a disease affecting peripheral nerves. Treatment has historically been conservative, as the natural course of the disease was thought to be self-limiting. Recent work has demonstrated that as many as two-thirds of people with NA have persistent pain, fatigue, or weakness. At the authors' center, supercharged end-to-side (SETS) nerve transfers are commonly performed in patients with NA to optimize motor recovery while allowing for native axonal regrowth. The authors describe the technique and clinical outcomes of patients with NA affecting the anterior interosseous nerve (AIN) who were treated with SETS nerve transfer from extensor carpi radialis brevis to AIN. Ten patients (90% male; mean age, 51.3 ± 9.7 years) underwent extensor carpi radialis brevis-to-AIN transfer at a mean period of 6.4 ± 1.4 months after onset of symptoms. Mean postoperative follow-up duration was 14.8 ± 3.2 months. Before surgery, all patients demonstrated clinically significant weakness in the flexor pollicis longus (FPL), flexor digitorum profundus muscle to the index finger (FDP2), or both. FPL strength improved from a median Medical Research Council (MRC) grade of 1.5 to 4 ( P = 0.011) and FDP2 strength improved from a median MRC grade of 1 to 5 ( P = 0.016). A postoperative MRC grade of 4 or greater was achieved in nine of 10 (90%) FPL and 10 of 10 (100%) FDP muscles. This is the first report of SETS nerve transfer for the treatment of NA. The outcomes of this work suggest that SETS nerve transfers may be an option to optimize motor outcomes in patients with NA.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

The hand diagram: A novel outcome measure following supercharged end-to-side anterior interosseous nerve to ulnar nerve transfer in severe compressive ulnar neuropathy

BACKGROUND

With advances in the surgical management for severe ulnar neuropathy with the introduction of the super charged-end-to-side (SETS) anterior interosseous nerve (AIN) to ulnar nerve transfer, a simple and reliable outcome measure is required. There is currently not "one" standardized outcome measure used to represent and compare results.

PURPOSE

To present the abduction hand diagram as a "novel", reproducible, and simple outcome measure for patients with severe ulnar neuropathy.

STUDY DESIGN

Retrospective case series.

METHODS

Nine patients with severe entrapment/compressive ulnar neuropathy at the elbow were reviewed. Clinical parameters included preoperative and postoperative abduction tracings, Medical Research Grade (MRC) muscle strength, key pinch strength, Disability of the Hand Arm and Shoulder (DASH) score, and crossed finger test. Electrodiagnostic data included change in compound muscle action potentials (CMAP) amplitude of the first dorsal interosseous (FDI), and abductor digiti minimi (ADM). Summary statistics were used for demographic and clinical data.

RESULTS

Average follow-up was 22.8 ± 9.3 months. At 18-months of follow up, 44% had ADM MRC grade 3 strength or higher, mean key pinch strength improved to 72 ± 19.3%, and mean DASH was 33 ± 28.7. There was a mean increase of 16.7 ± 9.1 mm and 31.5 ± 12 mm in total and summed hand abduction tracing measurements respectively.

CONCLUSIONS

Hand abduction tracings are a quantitative outcome measure to follow recovery over time for intrinsic hand function and can be used in patients with severe ulnar neuropathy following surgical intervention.

Primary Repair versus Reverse End-to-Side Coaptation by Anterior Interosseous Nerve Transfer in Proximal Ulnar Nerve Injuries

BACKGROUND

Proximal ulnar nerve lacerations are challenging to treat because of the complex integration of sensory and motor function in the hand. The purpose of this study was to compare primary repair and primary repair plus anterior interosseous nerve (AIN) reverse end-to-side (RETS) coaptation in the setting of proximal ulnar nerve injuries.

METHODS

A prospective cohort study was performed of all patients at a single, academic, level I trauma center from 2014 to 2018 presenting with isolated complete ulnar nerve lacerations. Patients underwent either primary repair (PR) only or primary repair and AIN RETS (PR + RETS). Data collected included demographic information; quick Disabilities of the Arm, Shoulder and Hand questionnaire score; Medical Research Council score; grip and pinch strength; and visual analogue scale pain scores at 6 and 12 months postoperatively.

RESULTS

Sixty patients were included in the study: 28 in the PR group and 32 in the RETS + PR group. There was no difference in demographic variables or location of injury between the two groups. Average quick Disabilities of the Arm, Shoulder and Hand questionnaire scores for the PR and PR + RETS groups were 65 ± 6 and 36 ± 4 at 6 months and 46 ± 4 and 24 ± 3 at 12 months postoperatively, respectively, and were significantly lower in the PR + RETS group at both points. Average grip and pinch strength were significantly greater for the PR + RETS group at 6 and 12 months.

CONCLUSION

This study demonstrated that primary repair of proximal ulnar nerve injuries plus AIN RETS coaptation yielded superior strength and improved upper extremity function when compared with PR alone.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, II.

Challenges in Nerve Repair and Reconstruction

Peripheral nerve injuries may substantially impair a patient's function and quality of life. Despite appropriate treatment, outcomes often remain poor. Direct repair remains the standard of care when repair is possible without excessive tension. For larger nerve defects, nerve autografting is the gold standard. However, a considerable challenge is donor site morbidity. Processed nerve allografts and conduits are other options, but evidence supporting their use is limited to smaller nerves and shorter gaps. Nerve transfer is another technique that has seen increasing popularity. The future of care may include novel biologics and pharmacologic therapy to enhance regeneration.

Modern Treatment of Cubital Tunnel Syndrome: Evidence and Controversy

Cubital tunnel syndrome is the second most common peripheral mononeuropathy in the upper extremity. However, the diagnosis and treatment of cubital tunnel syndrome remains controversial without a standard algorithm. Although diagnosis can often be made from the patient's history and physical examination alone, electrodiagnostic studies, ultrasound, computed tomography (CT), and magnetic resonance image (MRI) can also be useful in diagnosing the disease and selecting the most appropriate treatment option. Treatment options include conservative nonoperative techniques as well as various surgical options, including in situ decompression with or without transposition, medial epicondylectomy, and nerve transfer in advanced disease. The purpose of this review is to summarize the most up-to-date literature regarding cubital tunnel syndrome and propose a treatment algorithm to provide clarity about the challenges of treating this complex patient population.

Factors Associated With Severity of Cubital Tunnel Syndrome at Presentation

BACKGROUND

The outcomes of cubital tunnel syndrome surgery are affected by preoperative disease severity. The aim of this study was to identify factors associated with clinical and electrodiagnostic severity of cubital tunnel syndrome at presentation.

METHODS

We retrospectively identified 213 patients with electrodiagnostically confirmed cubital tunnel syndrome who underwent cubital tunnel surgery from July 2008 to June 2013. Our primary response variable was clinical cubital tunnel syndrome severity assessed by the McGowan grade. Our secondary response variables were sensory nerve action potential (SNAP) recordability, presence of fibrillations, and motor nerve conduction velocities (CVs) in the abductor digiti minimi (ADM) and first dorsal interosseous (FDI). Bivariate analysis was used to screen for factors associated with disease severity; significant variables were selected for multivariable regression analysis.

RESULTS

Older age was associated with higher McGowan grade and diabetes mellitus was associated with unrecordable SNAPs on bivariate analysis. No other variables met inclusion criteria for multivariable regression analysis for McGowan grade or unrecordable SNAPs. Multivariable regression analysis showed older age and higher Distressed Communities Index (DCI) to be associated with decreased motor nerve CVs in ADM. Multivariable regression analysis showed higher body mass index (BMI) and higher DCI to be associated with decreased motor nerve CVs in FDI. No variable was associated with the presence of fibrillations.

CONCLUSIONS

A subset of patients with cubital tunnel syndrome may benefit from earlier referral for hand surgery evaluation and earlier surgery. Older patients, with higher BMI, with diabetes mellitus, and with economic distress are at higher risk for presentation with more severe disease.

Reverse End-to-Side Transfer to Ulnar Motor Nerve: Evidence From Preclinical and Clinical Studies

The disappointing outcomes of conventional nerve repair or grafting procedures for proximal ulnar nerve injuries have led the scientific community to search for better alternatives. The pronator quadratus branch of the anterior interosseous nerve has been transferred to the distal ulnar motor branch in a reverse end-to-side fashion with encouraging results. This transfer is now becoming commonly used as an adjunct to cubital tunnel decompression in patients with compressive ulnar neuropathy, underscoring the need for this knowledge transfer to the neurosurgical community. However, the mechanism of recovery after these transfers is not understood completely. We have reviewed the existing preclinical and clinical literature relevant to this transfer to summarize the current level of understanding of the underlying mechanisms, define the indications for performing this transfer in the clinic, and identify the complications and best practices with respect to the operative technique. We have also attempted to identify the major deficiencies in our current level of understanding of the recovery process to propose directions for future research.

Beyond the Cubital Tunnel: Use of Adjunctive Procedures in the Management of Cubital Tunnel Syndrome

BACKGROUND

Our management of cubital tunnel syndrome has expanded to involve multiple adjunctive procedures, including supercharged end-to-side anterior interosseous to ulnar nerve transfer, cross-palm nerve grafts from the median to ulnar nerve, and profundus tenodesis. We also perform intraoperative brief electrical stimulation in patients with severe disease. The aims of this study were to evaluate the impact of adjunctive procedures and electrical stimulation on patient outcomes.

METHODS

We performed a retrospective review of 136 patients with cubital tunnel syndrome who underwent operative management from 2013 to 2018. A total of 38 patients underwent adjunctive procedure(s), and 33 received electrical stimulation. A historical cohort of patients who underwent cubital tunnel surgery from 2009 to 2011 (n = 87) was used to evaluate the impact of adjunctive procedures. Study outcomes were postoperative improvements in Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire scores, pinch strength, and patient-reported pain and quality of life.

RESULTS

In propensity score-matched samples, patients who underwent adjunctive procedures had an 11.3-point greater improvement in DASH scores than their matched controls (P = .0342). In addition, patients who received electrical stimulation had significantly improved DASH scores relative to baseline (11.7-point improvement, P < .0001), whereas their control group did not. However, when compared between treatment arms, there were no significant differences for any study outcome.

CONCLUSIONS

Patients who underwent adjunctive procedures experienced greater improvement in postoperative DASH scores than their matched pairs. Additional studies are needed to evaluate the effects of brief electrical stimulation in compression neuropathy.

Interfascicular Anatomy of the Motor Branch of the Ulnar Nerve: A Cadaveric Study

PURPOSE

The motor branch of the ulnar nerve contains fascicles that innervate the intrinsic musculature of the hand. This cadaveric study aimed to describe the organization and consistency of the internal topography of the motor branch of the ulnar nerve.

METHODS

Five fresh-frozen cadaveric specimens with an average age of 74 years (range, 65-88 years) were dissected. The ulnar nerve was exposed and transfixed to the underlying tissues to maintain its orientation throughout the dissection. The dorsal cutaneous branch (DCB) and the volar sensory branch were identified and reflected to expose the motor branch. The fascicles to the first dorsal interosseus (FDI), flexor pollicis brevis, and abductor digiti minimi (ADM) were identified. Internal neurolysis was performed distal to proximal to identify the interfascicular arrangement of these fascicles within the motor branch. The organization of these fascicles was noted, and the branch points of the DCB, FDI, and ADM were measured relative to the pisiform using a handheld electronic caliper.

RESULTS

The internal topography of the motor branch was consistent among all specimens. Proximal to the pisiform, the arrangement from radial to ulnar was as follows: volar sensory branch, flexor pollicis brevis, FDI/intrinsic muscles, ADM, and DCB. The position of these branches remained consistent as the deep motor branch curved radially within the palm and traveled to the terminal musculature. The locations of the average branch points of the FDI, ADM, and DCB with respect to the pisiform were as follows: FDI, 4.6 cm distal (range, 4.1-4.9 cm), 4.5 cm radial (range, 4.1-4.9 cm); ADM, 0.65 cm distal (range, 0.3-1.1 cm), 0.7 cm radial (range, 0.3-1.1 cm), DCB, 7.7 cm proximal (range, 4.2-10.1 cm), and 0.4 cm ulnar (range, 0.3-0.8 cm).

CONCLUSIONS

The internal topography of the ulnar nerve motor branch was consistent among the specimens studied. The topography of the motor branches was maintained as the motor branch turns radially within the palm.

CLINICAL RELEVANCE

This study provides further understanding of the internal topography of the ulnar nerve motor branch at the wrist level.

Reverse End-to-Side Nerve Transfer for Severe Ulnar Nerve Injury: A Western Canadian Multicentre Prospective Nonrandomized Cohort Study

BACKGROUND

Reverse end-to-side (RETS) nerve transfer has become increasingly popular in patients with severe high ulnar nerve injury, but the reported outcomes have been inconsistent.

OBJECTIVE

To evaluate the "babysitting effect," we compared outcomes after anterior interosseous nerve RETS transfer with nerve decompression alone. To evaluate the source of regenerating axons, a group with end-to-end (ETE) transfer was used for comparisons.

METHODS

Electrophysiology measures were used to quantify the regeneration of anterior interosseous nerve (AIN) and ulnar nerve fibers while functional recovery was evaluated using key pinch and Semmes-Weinstein monofilaments. The subjects were followed postsurgically for 3 years.

RESULTS

Sixty-two subjects (RETS = 25, ETE = 16, and decompression = 21) from 4 centers in Western Canada were enrolled. All subjects with severe ulnar nerve injury had nerve compression at the elbow except 10 in the ETE group had nerve laceration or traction injury. Postsurgically, no reinnervation from the AIN to the abductor digiti minimi muscles was seen in any of the RETS subjects. Although there was no significant improvement in compound muscle action potentials amplitudes and pressure detection thresholds in the decompression and RETS group, key pinch strength significantly improved in the RETS group ( P < .05).

CONCLUSION

The results from published clinical trials are conflicting in part because crossover regeneration from the donor nerve has never been measured. Unlike those with ETE nerve transfers, we found that there was no crossover regeneration in the RETS group. The extent of reinnervation was also no different from decompression surgery alone. Based on these findings, the justifications for this surgical technique need to be carefully re-evaluated.

Classifying the Severity of Cubital Tunnel Syndrome: A Preoperative Grading System Incorporating Electrodiagnostic Parameters

BACKGROUND

Current classifications for cubital tunnel syndrome have not been shown to reliably predict postoperative outcomes. In this article, the authors introduce a new classification that incorporates clinical and electrodiagnostic parameters, including compound muscle action potential amplitude, to classify the preoperative severity of cubital tunnel syndrome. The authors compare this to established classifications and evaluate its association with patient-rated improvement.

METHODS

The authors reviewed 44 patients who were treated surgically for cubital tunnel syndrome. Patients were retrospectively classified using their proposed classification and the Akahori, McGowan-Goldberg, Dellon, and Gu classifications. Correlation of grades was assessed by Spearman coefficients and agreement was assessed by weighted kappa coefficients. Patient-reported impairment was assessed using the Disabilities of the Arm, Shoulder, and Hand questionnaire before and after surgery.

RESULTS

The classifications tended to grade patients in a similar way, with Spearman coefficients of 0.60 to 0.85 ( p < 0.0001) and weighted kappa coefficients of 0.46 to 0.71 ( p < 0.0001). Preoperative Disabilities of the Arm, Shoulder, and Hand scores increased with severity grade for most classifications. In multivariable analysis, the authors' classification predicted postoperative Disabilities of the Arm, Shoulder, and Hand score improvement, whereas established classifications did not.

CONCLUSIONS

Established classifications are imperfect indicators of preoperative severity. The authors introduce a preoperative classification for cubital tunnel syndrome that incorporates electrodiagnostic findings in addition to classic signs and symptoms.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Diagnostic, III.

Anterior Interosseous Nerve to Ulnar Nerve Transfer: A systematic review

Background

Objectives

Methods

Results

Conclusion

The management of failed cubital tunnel decompression

Cubital tunnel decompression is a commonly performed operation with a much higher failure rate than carpal tunnel release.

Failed cubital tunnel release generally occurs due to an inadequate decompression in the primary procedure, new symptoms due to an iatrogenic cause, or development of new areas of nerve irritation.

Our preferred technique for failed release is revision circumferential neurolysis with medial epicondylectomy, as this eliminates strain, removes the risk of subluxation, and avoids the creation of secondary compression points.

Adjuvant techniques including supercharging end-to-side nerve transfer and nerve wrapping show promise in improving the results of revision surgery.

Limited quality research exists in this subject, compounded by the lack of consensus on diagnostic criteria, classification, and outcome assessment.

Cite this article: EFORT Open Rev 2021;6:735-742. DOI: 10.1302/2058-5241.6.200135

Compression Neuropathies of the Upper Extremity: A Review

Compressive neuropathies of the forearm are common and involve structures innervated by the median, ulnar, and radial nerves. A thorough patient history, occupational history, and physical examination can aid diagnosis. Electromyography, X-ray, and Magnetic Resonance Imaging may prove useful in select syndromes. Generally, first line therapy of all compressive neuropathies consists of activity modification, rest, splinting, and non-steroidal anti-inflammatory drugs. Many patients experience improvement with conservative measures. For those lacking adequate response, steroid injections may improve symptoms. Surgical release is the last line therapy and has varied outcomes depending on the compression. Carpal Tunnel syndrome (CTS) is the most common, followed by ulnar tunnel syndrome. Open and endoscopic CTS release appear to have similar outcomes. Endoscopic release appears to incur decreased cost baring a low rate of complications, although this is debated in the literature. Additional syndromes of median nerve compression include pronator syndrome (PS), anterior interosseous syndrome, and ligament of Struthers syndrome. Ulnar nerve compressive neuropathies include cubital tunnel syndrome and Guyon’s canal. Radial nerve compressive neuropathies include radial tunnel syndrome and Wartenberg’s syndrome. The goal of this review is to provide all clinicians with guidance on diagnosis and treatment of commonly encountered compressive neuropathies of the forearm.

Cubital tunnel syndrome

Cubital tunnel syndrome (CuTS) is the second most common compression neuropathy of the upper limb, presenting with disturbance of ulnar nerve sensory and motor function.The ulnar nerve may be dynamically compressed during movement, statically compressed due to reduction in tunnel volume or compliance, and tension forces may cause ischaemia or render the nerve susceptible to subluxation, further causing local swelling, compression inflammation and fibrosis.Superiority of one surgical technique for the management of CuTS has not been demonstrated. Different techniques are selected for different clinical situations with simple decompression being the most common procedure due to its efficacy and low complication rate.Adjunctive distal nerve transfer for denervated muscles using an expendable motor nerve to restore the axon population in the distal nerve is in its infancy but may provide a solution for severe intrinsic weakness or paralysis. Cite this article: EFORT Open Rev 2021;6:743-750. DOI: 10.1302/2058-5241.6.200129.

Restoration of the first dorsal interosseous muscle

Motor dysfunction of the 1^st dorsal interosseous (DIO) muscle is typically observed in low and high ulnar nerve palsy. This causes weak thumb-index pinch, which can be disabling for the patient. Various reconstructive techniques have been described; however, the choice often depends on the surgeon's experience, the presence of associated neurovascular and musculotendinous injuries, as well as the requirements of the palliative surgery schedule. Nerve transfers can be proposed when patients present early in the course of the disease. Tendon transfers are often a last resort when late presentation occurs. Tendon transfers must follow general principles: the insertion is made on the 1^st DIO terminal tendon; the tension must be adjusted in a neutral position to avoid excessive tension, and immobilization is maintained for 4 weeks. Although many transfers are possible, the extensor pollicis brevis transfer is our preferred option. This donor does not require additional tendon grafting, has a direct line of pull close to that of the 1^st DIO and is not often used for other reconstructive purposes.

Role of electrodiagnosis in nerve transfers for focal neuropathies and brachial plexopathies

Over the past 2 decades, the surgical treatment of brachial plexus and peripheral nerve injuries has advanced considerably. Nerve transfers have become an important surgical tool in addition to nerve repair and grafting. Electrodiagnosis has traditionally played a role in the diagnosis and localization of peripheral nervous system injuries, but a different approach is needed for surgical decision-making and monitoring recovery. When patients have complete or severe injuries they should be referred to surgical colleagues early after injury, as outcomes are best when nerve transfers are performed within the first 3 to 6 mo after onset. Patients with minimal recovery of voluntary activity are particularly challenging, and the presence of a few motor unit action potentials in these individuals should be interpreted on the basis of timing and evidence of ongoing reinnervation. Evaluation of potential recipient and donor muscles, as well as redundant muscles, for nerve transfers requires an individualized approach to optimize the chances of a successful surgical intervention. Anomalous innervation takes on new importance in these patients. Communication between surgeons and electrodiagnostic medicine specialists (EMSs) is best facilitated by a joint collaborative clinic. Ongoing monitoring of recovery post-operatively is critical to allow for decision making for continued surgical and rehabilitation treatments. Different electrodiagnostic findings are expected with resolution of neurapraxia, distal axon sprouting, and axonal regrowth. As new surgical techniques become available, EMSs will play an important role in the assessment and treatment of these patients with severe nerve injuries.

Five Reliable Nerve Transfers for the Treatment of Isolated Upper Extremity Nerve Injuries

LEARNING OBJECTIVES

After studying this article and accompanying videos, the participant should be able to: 1. Understand and apply the principles of nerve transfer surgery for nerve injuries. 2. Discuss important considerations when performing nerve transfers, such as aspects of surgical technique and perioperative decision-making. 3. Understand indications for end-to-end versus supercharged reverse end-to-side nerve transfers. 4. Understand an algorithm for treating nerve injuries to include the indications and surgical techniques of five nerve transfers commonly performed for the treatment of isolated upper extremity nerve injuries. 5. Understand the outcomes and postoperative management of the discussed nerve transfers.

SUMMARY

Nerve transfers are gaining wide acceptance because of their superior results in the management of many nerve injuries of the upper extremity. This article presents five nerve transfers for the treatment of isolated nerve injuries in the authors' upper extremity nerve practice that offer reliable results. Indications, surgical techniques, outcomes, and postoperative management are reviewed. To maximize functional outcomes in patients with nerve injuries, the treatment should be individualized to the patient, and the principles for nerve transfers as described herein should be considered.