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.

Round table discussion: the management of idiopathic cubital tunnel syndrome.

Idiopathic cubital tunnel syndrome is the second most common neuropathy in the upper limb. Best evidence regarding the surgical management of this condition has evolved from anterior or submuscular transposition as the former reference standard, to in situ simple release. Differences of opinion remain regarding the timing of surgery, type of surgery and adjunctive surgery. Four surgeons with Level 5 expertise were asked to answer specific questions regarding this condition.

Supercharging of the ulnar nerve: clinical and neurophysiological assessment at 2 years for nine proximal injuries.

LEVEL OF EVIDENCE: II.

Neuralgic Amyotrophy and Hourglass Nerve Constriction/Nerve Torsion: Two Sides of the Same Coin? A Clinical Review.

Neuralgic amyotrophy, also called Parsonage-Turner syndrome, in its classic presentation is a brachial plexopathy or a multifocal neuropathy, involving mainly motor nerves of the upper limb with a monophasic course. Recently, a new radiological entity was described, the hourglass constriction, which is characterized by a very focal constriction of a nerve, or part of it, usually associated with nerve thickening proximally and distally to the constriction. Another condition, which is similar from a radiological point of view to hourglass constriction, is nerve torsion. The pathophysiology of neuralgic amyotrophy, hourglass constriction and nerve torsion is still poorly understood, and a generic role of inflammation is proposed for all these conditions. It is now widely accepted that nerve imaging is necessary in identifying hourglass constrictions/nerve torsion pre-surgically in patients with an acute mononeuropathy/plexopathy. Ultrasound and MRI are useful tools for diagnosis, and they are consistent with intraoperative findings. The prognosis is generally favorable after surgery, with a high rate of good motor recovery.

[MR neurography reveals fascicular constriction of the median nerve in a patient with neuralgic amyotrophy].

Diagnosing neuralgic amyotrophy can be challenging in clinical practice. Here, we report the case of a 37-years old Japanese woman who suddenly developed neuropathic pain in the right upper limb after influenza vaccination. The pain, especially at night, was severe and unrelenting, which disturbed her sleep. However, X-ray and MRI did not reveal any fractures or muscle injuries, and brain MRI did not reveal any abnormalities. During neurological consultation, she was in a posture of flexion at the elbow and adduction at the shoulder. Manual muscle testing suggested weakness of the flexor pollicis longus, pronator quadratus, flexor carpi radialis (FCR), and pronator teres (PT), while the flexor digitorum profundus was intact. Medical history and neurological examination suggested neuralgic amyotrophy, particularly anterior interosseous nerve syndrome (AINS) with PT/FCR involvement. Innervation patterns on muscle MRI were compatible with the clinical findings. Conservative treatment with pain medication and oral corticosteroids relieved the pain to minimum discomfort, whereas weakness remained for approximately 3 months. For surgical exploration, lesions above the elbow and fascicles of the median nerve before branching to the PT/FCR were indicated on neurological examinations; thus, we performed high-resolution imaging to detect possible pathognomonic fascicular constrictions. While fascicular constrictions were not evident on ultrasonography, MR neurography indicated fascicular constriction proximal to the elbow joint line, of which the medial topographical regions of the median nerve were abnormally enlarged and showed marked hyperintensity on short-tau inversion recovery. In patients with AINS, when spontaneous regeneration cannot be expected, timely surgical exploration should be considered for a good outcome. In our case, MR neurography was a useful modality for assessing fascicular constrictions when the imaging protocols were appropriately optimized based on clinical assessment.

Index Finger Flexor Digitorum Profundus Function Deficit after Shoulder Arthroscopy Treated by Neurolysis: A Case Report.

A 60-year-old woman presented functional deficit of the index finger flexor digitorum profundus (FDP) tendon after shoulder arthroscopic rotator cuff repair. As no recovery was observed for 10 months, we conducted an operative exploration of the median nerve and the anterior interosseous nerve, followed by an external neurolysis. The patient recovered FDP function 4.5 months after the second operation. In a patient with persistent isolated FDP dysfunction after shoulder arthroscopy, operative exploration and external neurolysis could facilitate functional recovery. Level of Evidence: Level V (Therapeutic).

Supercharged End-to-Side Nerve Transfer for Ulnar Neuropathy: Redefining Nomenclature and Recommendations for Standardisation of Surgical Technique Description.

Supercharged end-to-side (SETS) nerve transfers have been described as a treatment option for ulnar neuropathy, however, there is inconsistency in the nomenclature used to describe the microsurgical technique. The purpose of this article is to systematically review the available literature on the SETS nerve transfer technique and to provide an overview of the technical variations to facilitate standardisation of surgical method. A literature review was performed through PubMed, MEDLINE, and Ovid databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies that reported surgical technique of anterior interosseous nerve (AIN) to ulnar nerve SETS transfer were included. Studies were excluded when not referencing SETS/reverse end-to-side (RETS) nerve transfers, studies referencing nerve transfers other than AIN to motor fascicle bundle of the ulnar nerve (MUN), animal studies, and studies not reporting technique. Of the 168 studies found, 14 articles were included. In five articles, distal visualisation of the MUN in Guyon's canal was specifically cited. In the four studies that commented on donor preparation, sharp neurectomy proximal to the AIN branching point was undertaken. Recipient preparation was commented on in seven of the included studies. Two studies referred to an epineurial window only while five specifically recommended a perineurial window. Coaptation site was specified in four studies and all studies used sutures for coaptation, with four articles stipulating that 9-0 nylon was used. Additionally, fibrin glue was used in conjunction with suture technique in four studies. Consistency in nomenclature used to describe SETS microsurgical technique is needed before case series measuring outcome can be reliably interpreted. This review allowed for the development of suggestions for standardisation of nomenclature and minimal reporting requirements when describing SETS technique. Standardisation of technique will allow for reproducibility and facilitate future evaluations of outcome in prospective randomised control trials.

Persistent Hourglass Constriction in Recovered Anterior Interosseous Nerve Palsy Due to Neuralgic Amyotrophy: A Case Report.

The current articles recommended the interfascicular neurolysis for anterior interosseous nerve (AIN) palsy with hourglass-like fascicular constrictions (FCs) detected by ultrasonography or surgical exploration to realign to the fascicular torsion for those who failed to recover spontaneously. We present the case report of spontaneous AIN palsy recovered after conservative treatment; however, ultrasonographic findings showed persistent FCs of AIN in the arm at the beginning, at 6 weeks, and subsequent 3-year follow-ups, even after complete clinical recovery of palsy. This finding calls into question the current notion that AIN paralysis is due to FCs and that neurolysis is the best surgical treatment when spontaneous recovery does not occur for a considerable observation period. Level of Evidence: Level V (Therapeutic).

Hourglass-like constriction of the anterior interosseous nerve in the left forearm: A case report.

BACKGROUND: Hourglass-like constriction neuropathy is a rare neurological disorder. The main clinical manifestation is peripheral nerve injury with no apparent cause, and the pathomorphological change is an unexplained narrowing of the diseased nerve. The diagnosis and treatment of the disease are challenging and there is no accepted diagnostic or therapeutic approach. CASE SUMMARY: This report describes a rare hourglass constriction of the anterior interosseous nerve in the left forearm in a 47-year-old healthy male who was treated surgically and gradually recovered function over a 6-mo follow-up period. CONCLUSION: Hourglass-like constriction neuropathy is a rare disorder. With the development of medical technology, more examinations are now available for diagnosis. This case aims to highlight the rare manifestations of Hourglass-like constriction neuropathy and provides a reference for enriching the clinical diagnosis and treatment experience.

Kiloh-Nevin syndrome: an unusual cause of forearm pain.

The popularity of weight training, bodybuilding and general physical conditioning has led to an increased rate of musculoskeletal injuries, such as nerve compression caused by muscle hypertrophy and, stretching of nerves peripherally. We present a case of anterior interosseous nerve (AIN) entrapment syndrome/neuropathy otherwise known as Kiloh-Nevin syndrome in a 22-year-old weightlifter. Knowledge of this injury is paramount for practitioners to increase awareness among athletes and bodybuilders.

Anterior interosseous nerve syndrome following infection with COVID-19: a case report.

BACKGROUND: Various neurological manifestations associated with coronavirus disease 2019 have been increasingly reported. Herein, we report a rare case of anterior interosseous nerve syndrome, which occurred 5 days after the onset of coronavirus disease 2019. CASE PRESENTATION: A 62-year-old Asian woman with a history of coronavirus disease 2019 who developed a complete motor deficit in the left flexor pollicis longus and pronator quadratus without sensory deficits. The symptoms appeared as a sudden onset fatigue and severe pain of the left arm, 5 days after the onset of coronavirus disease 2019. She noticed paralysis of the left thumb at 2 weeks after the onset of coronavirus disease 2019. Electromyography assessment of the anterior interosseous nerve-dominated muscles revealed neurogenic changes such as positive sharp wave and fibrillation in flexor pollicis longus and pronator quadratus, confirming the diagnosis of anterior interosseous nerve syndrome. There were no other diseases that could have resulted in peripheral nerve palsy. We performed a functional reconstruction surgery of the thumb by tendon transfer from the extensor carpi radialis longus to the flexor pollicis longus. The patient reported a good patient-reported outcome (2.27 points in QuickDASH Disability/Symptom scoring and 5 points in Hand20 scoring) at final follow-up (1 year after the surgery). CONCLUSION: This case highlights the need for vigilance regarding the possible development of anterior interosseous nerve syndrome in patients with coronavirus disease 2019. Tendon transfer from extensor carpi radialis longus to flexor pollicis longus can provide good functional recovery for unrecovered motor paralysis after anterior interosseous nerve syndrome.

A rat model of modified contralateral C7 transfer permitting ulnar nerve recovery.

BACKGROUND: Contralateral C7 transfer (cC7) is an important treatment for total brachial plexus avulsion (TBPA), which sacrifices the recovery of the ulnar nerve (UN). The present study aimed to introduce an animal model of modified cC7 that preserved the deep branch of ulnar nerve (dbUN) and verify its feasibility. METHODS: Anatomical study: Lengths, diameters, and axon counts of dbUN and anterior interosseous (AIN) branches in six rats were measured. In vivo surgery: 18 rats were divided into three groups. Group A: Traditional cC7. Group B: Modified cC7 finished in one stage. Group C: Modified cC7 and AIN branch anastomosed with dbUN one month after the first stage. Electrophysiological examinations, muscle wet weight, muscle cross-sectional areas, and nerve axon counts were evaluated six months postoperatively. RESULTS: Anatomical study: The distances from dbUN and AIN branches to the midpoint of the inner and outer epicondyles connection of the humerus, diameters, and axon numbers of dbUN and AIN branches were analyzed, then AIN terminal branch (tbAIN) was anastomosed with dbUN. In vivo surgery: The differences in median nerve fiber counts were not significant. There were more UN axons in group A than in groups B and C. In electrophysiological examinations, muscle wet weight and cross-sectional area of the flexor digitorum profundus showed no significant difference, but the second interosseus cross-sectional areas in groups B and C were significantly larger than in group A. CONCLUSIONS: This study established an animal model of preserving dbUN in cC7 and verified its feasibility. The possibility of restoring dbUN was established.

Modified contralateral C7 transfer to restore ulnar nerve function without sacrificing median nerve recovery: an experimental study.

Contralateral C7 (cC7) transfer is a technique used in patients with total brachial plexus avulsion. An ulnar nerve graft (UNG) is usually used, as intrinsic function is not expected to be restored due to length of reinnervation required. In this study, we attempted to improve intrinsic function recovery by preserving the deep branch of the ulnar nerve (dbUN) and reanimating it with the anterior interosseous nerve (AIN) after cC7 transfer. Fifty-four rats were divided into the following three groups: Group A, traditional cC7 transfer to the median nerve with a UNG; Group B, cC7 transfer preserving and repairing the dbUN with the terminal branch of the AIN; Group C, same as Group B; however, the dbUN was coapted after 1 month with the AIN. At 3, 6 and 9 months postoperatively, the results of electrodiagnostic and histomorphometric examinations of the interosseous muscle were significantly better in Groups B and C, without affecting AIN recovery. In conclusion, the modified cC7 transfer technique can potentially improve intrinsic function recovery without affecting median nerve recovery.

Anterior Interosseous Nerve to Ulnar Nerve Transfers: A Systematic Review.

Background There has been an increasing utilization of end-to-end (ETE) and reverse "supercharged" end-to-side (SETS) anterior interosseous nerve (AIN) to ulnar nerve transfers (NTs) for treatment of high ulnar nerve injury. This study aimed to review the potential indications for, and outcomes of, ETE and SETS AIN-ulnar NT. Methods A literature review was performed, and 10 articles with 156 patients who had sufficient follow-up to evaluate functional outcomes were included. English studies were included if they reported the outcome of patients with ulnar nerve injuries treated with AIN to ulnar motor NT. Outcomes were analyzed based on the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire scores, grip and key pinch strength, and interosseous Medical Research Council-graded motor strength. Comparisons were made using the independent t -test and the chi-square test. No nerve graft control group was required for eligibility. Ulnar nerve injury types varied. Results NT resulted in 77% of patients achieving M3+ recovery, 53.7 ± 19.8 lb grip strength recovery, 61 ± 21% key pinch recovery, and a mean DASH score of 33.4 ± 16. In this diverse group, NT resulted in significantly greater M3+ recovery and grip strength recovery measured in pounds than in the nerve graft/conventional treatment group, and ETE repairs had significantly better outcomes compared with SETS repairs for grip strength, key pinch strength, and DASH scores, but heterogeneity limits interpretation. Conclusion ETE and SETS AIN-ulnar NTs produce significant restoration of ulnar nerve motor function for high ulnar nerve injuries. For ulnar nerve transection injuries at or above the elbow, ETE NT results in superior motor recovery compared with nerve grafting/conventional repair. However, further research is needed to determine the best treatment for other types of ulnar nerve injury and the role of SETS NT.

Anterior interosseous nerve palsy in the early postoperative period after open capsular release for elbow stiffness: a case report.

Surgical release of elbow contracture is associated with injury to structures traversing the elbow. To date, only one other case report has been published describing anterior interosseous nerve (AIN) palsy that developed immediately after open elbow contracture release and debridement. Here we describe the unique case of a patient that developed AIN palsy 1 week after operation, including magnetic resonance imaging and electrodiagnostic studies, to shed some light on the etiology of this rare complication.

Outcomes after Anterior Interosseous Nerve to Ulnar Motor Nerve Transfer.

Background Ulnar nerve lesions proximal to the elbow can result in loss of intrinsic muscle function of the hand. The anterior interosseous nerve (AIN) to deep motor branch of the ulnar nerve (DBUN) transfer has been demonstrated to provide intrinsic muscle reinnervation, thereby preventing clawing and improving pinch and grip strength. The purpose of this study was to evaluate the efficacy of the AIN to DBUN transfer in restoring intrinsic muscle function for patients with traumatic ulnar nerve lesions. Methods We performed a prospective, multi-institutional study of outcomes following AIN to DBUN transfer for high ulnar nerve injuries. Twelve patients were identified, nine of which were enrolled in the study. The mean time from injury to surgery was 15 weeks. Results At final follow-up (mean postoperative follow-up 18 months + 15.5), clawing was observed in all nine patients with metacarpophalangeal joint hyperextension of the ring finger averaging 8.9 degrees (+ 10.8) and small finger averaging 14.6 degrees (+ 12.5). Grip strength of the affected hand was 27% of the unaffected extremity. Pinch strength of the affected hand was 29% of the unaffected extremity. None of our patients experienced claw prevention after either end-to-end ( n = 4) or end-to-side ( n = 5) AIN to DBUN transfer. Conclusion We conclude that, in traumatic high ulnar nerve injuries, the AIN to DBUN transfer does not provide adequate intrinsic muscle reinnervation to prevent clawing and normalize grip and pinch strength.

Transfer of extensor carpi radialis brevis branch of radial nerve to anterior interosseous nerve for lower trunk brachial plexopathy after motor vehicle accident.

The patient is a 15-year-old male who sustained injury to his right lower brachial plexus (C8-T1) in a motor vehicle accident. Six months after the injury, the patient still had persistent hand weakness and wished to regain function in his first and second digits. Transfer of the extensor carpi radialis brevis (ECRB) branch of the radial nerve to the anterior interosseous nerve (AIN) was performed to restore motor function. The patient did well after the surgery, although it may take 12-24 months for benefits to fully manifest. Pertinent surgical anatomy and techniques are highlighted in this video demonstration. The video can be found here: https://stream.cadmore.media/rr10.3171/2022.10.FOCVID2287.

Distal anterior interosseous nerve to ulnar nerve motor branch reverse end-to-side transfer in a case of severe ulnar neuropathy.

Reverse end-to-side (RETS) distal transfer is gaining popularity in cases of proximal nerve damage with the nerve in continuity, allowing the nerve to potentially retain its ability to regenerate and recover. While preserving the original axon pool, RETS could provide an additional pool of motor axons and/or possibly "babysit" the muscle endplates and distal denervated nerve Schwann cells until reinnervation from the original pool occurs. The authors present a video demonstrating anterior subcutaneous transposition of the ulnar nerve at the elbow coupled with a distal anterior interosseous nerve to ulnar nerve RETS in a case of severe posttraumatic ulnar neuropathy at the elbow. The video can be found here: https://stream.cadmore.media/r10.3171/2022.9.FOCVID2282.

Nerve Ultrasonography for the Diagnosis and Evaluation of Neuralgic Amyotrophy.

Neuralgic amyotrophy (NA) is a peripheral nervous system disorder involving multifocal distribution. Although nerve ultrasonography has shown potential for detecting NA lesions, no established detection method exists for distal forearm NA. A 59-year-old man presented with weakness of the muscles innervated by the left posterior interosseous nerve (PIN), median nerve (MN), anterior interosseous nerve (AIN), and ulnar nerve (UN), following severe left shoulder pain. This case suggests that nerve ultrasonography can help accurately diagnose distal forearm NA.