Outcomes after Anterior Interosseous Nerve to Ulnar Motor Nerve Transfer

Histological study of donor/recipient feasibility in distal nerve transfer for the upper limb nerve injury

This study aimed to histologically investigate whether the compatibility of donor and recipient nerves in distal nerve transfer for radial and ulnar nerve palsy is suitable for restoring nerve function. Partial median to radial nerve transfer for radial nerve palsy and partial median to ulnar nerve transfer for ulnar nerve palsy were performed in 10 cadaveric upper limbs fixed using the Thiel technique. Histological analysis of the nerve samples at the coaptation site focused on the number of myelinated axons. Each recipient and donor nerve was identified in all specimens without any anatomical variations. While median-radial nerve transfer techniques showed an adequate number of donor axons, median-ulnar nerve transfer techniques showed a shortage of donor axons. The insufficiency of donor axons compared to the recipient axons may explain the challenges in reinnervating the recipient muscles. Combining the two different nerve transfers may compensate for the shortage of donor axons and improve motor recovery. Type of study and Level of evidence: Therapeutic, Level III.

Anatomical Characterization of the Motor Branch to the Fourth Lumbrical: A Cadaver Study

PURPOSE

The branching pattern of the deep motor branch of the ulnar nerve (DBUN) in the hand is complex. The anatomy of the motor branch innervating the fourth lumbrical (4L), where paralysis results in a claw hand deformity after ulnar nerve injury, is not well defined. This cadaver study focused on mapping and defining anatomical landmarks in relation to the motor branch to the 4L.

METHODS

Ten fresh-frozen cadaver hands were dissected. The DBUN was exposed and followed distally, identifying all motor branches, until the branch to the 4L was seen. The small finger flexor tendons were reflected distally to enable visualization of the entire 4L motor branch and its distal entry point. The origin of the 4L motor branch was mapped in relation to fixed anatomical landmarks in the hand.

RESULTS

A consistent motor branch to the 4L and third palmar interosseous (3PI) muscles was seen originating from the DBUN in all specimens. The mean number of motor branches innervating the hypothenar muscles proximal to the 4L/3PI motor branch was 2.1 (range 1 to 5). The mean distance from the origin of the DBUN to the 4L/3PI motor branch was 2.9 cm (range 2.5 to 4.2 cm). The mean length of the 4L/3PI branch was 3.1 cm (range 2.3 to 4.5 cm). In seven specimens, the 4L/3PI branch demonstrated an intramuscular course through the 3PI before terminating in the 4L. In three specimens the 4L/ 3PI branch ran on the volar surface of the 3PI before terminating in the 4L.

CONCLUSIONS

A consistent 4L/3PI motor branch was mapped and characterized in all specimens.

CLINICAL RELEVANCE

These findings provide a guide for intraoperative localization of the 4L/3PI motor branch and also may provide further evidence to explain findings seen after distal nerve transfers to treat ulnar nerve injury.

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

LEVEL OF EVIDENCE

II.

Reconstructing Pinch Strength after Ulnar Nerve Injury by Transferring the Opponens Pollicis Motor Branch

BACKGROUND

With ulnar nerve injuries, paralysis of the first dorsal interosseous and adductor pollicis muscle weakens the patient's pinch. In the palm, we transferred the opponens pollicis motor branch to the deep terminal division of the ulnar nerve for pinch reconstruction.

METHODS

Sixteen patients with ulnar nerve injuries around the elbow underwent reconstruction and were followed up postoperatively for a minimum of 14 months. Their mean age was 41 ± 16 years, and the mean interval between injury and surgery was 134 ± 126 days (range, 2 to 390 days). Preoperatively and postoperatively, grasp, key, and subterminal key pinch strength were measured using dynamometers.

RESULTS

Reinnervation of the first dorsal interosseous muscle was observed in 15 of the 16 patients. Mean grasp strength improved from 15.5 ± 8.5 kg preoperatively to 24 ± 10 kg postoperatively, achieving 57% ± 16% of contralateral hand strength. Preoperatively, terminal key pinch averaged 3 ± 1 kg, which improved postoperatively to 5.5 ± 2 kg, achieving 71 ± 24% of the strength measured contralaterally. Preoperatively to postoperatively, subterminal key pinch force increased from 0 to 2.4 ± 1.3 kg, achieving 61% ± 27% that of the unaffected side. Patients who underwent surgery within 6 months of their injury showed a mean subterminal key pinch strength recovery of 63% ± 27% of the normal side, whereas those who underwent surgery between 7 and 13 months after injury showed a mean subterminal key pinch strength recovery of 51% ± 29%.

CONCLUSION

Transferring the opponens pollicis motor branch to the deep terminal division of the ulnar nerve improved pinch and grasp strength without jeopardizing thumb function.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

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.

Updates in peripheral nerve surgery of the upper extremity: diagnosis and treatment options

The loss of function resulting from peripheral nerve injuries confers a significant burden to the patient and society. The treatment of peripheral nerve injuries requires an accurate diagnosis and formulation of a functional reconstructive plan. Advances in peripheral nerve imaging complement electrodiagnostic studies, and provide us with detailed information regarding the status of nerve injury, repair, and regeneration in order to prognosticate recovery and determine the need for surgical intervention. When direct nerve repair is not possible, the methods for bridging a nerve gap are the nerve autograft, allograft and conduit. While current research supports the use of conduits and nerve allografts for shorter nerve gaps, the nerve autograft still remains the gold standard for bridging a nerve gap. When direct nerve repair or nerve grafting fails, or is anticipated to be insufficient, nerve transfers are an alternative for reconstruction. Knowledge of axonal counts, upper limb innervation patterns, location and clustering of upper limb peripheral nerves allows for the design of new nerve transfers. The options of nerve transfers for radial, ulnar and median nerve injuries are outlined, as well as their outcomes. Nerve transfers are an attractive option for restoring motor and sensory function while minimizing donor site morbidity. However, one must consider their limitations, and preserve donor sites for secondary tendon transfer options. This article presents the latest information regarding the imaging of peripheral nerves, methods to bridge a nerve gap, and nerve transfers to aid the peripheral nerve surgeon in choosing a reconstructive plan.