A Fresh Cadaver Study on the Innervation of Brachioradialis and Extensor Carpi Radialis Longus Muscles

PURPOSE

Distal nerve transfers have revolutionized peripheral nerve surgery by allowing the transfer of healthy motor nerves to paralyzed ones without causing additional morbidity. Radial nerve branches to the brachialis (Ba), brachioradialis (Br), and extensor carpi radialis longus (ECRL) muscles have not been investigated in fresh cadavers.

METHODS

The radial nerve and its branches were dissected in 34 upper limbs from 17 fresh cadavers. Measurements were taken to determine the number, origin, length, and diameter of the branches. Myelinated fiber counts were obtained through histological analysis.

RESULTS

The first branch of the radial nerve at the elbow was to the Ba muscle, followed by the branches to the Br and ECRL muscles. The Ba and Br muscles consistently received single innervation. The ECRL muscle showed varying innervation patterns, with one, two, or three branches. The branches to the Br muscles originated from the anterior side of the radial nerve, whereas the branches to the Ba and ECRL muscles originated from the posterior side. The average myelinated fiber counts favored the nerve to Br muscle over that to the ECRL muscle, with counts of 542 versus 350 and 568 versus 302 observed in hematoxylin and eosin and neurofilament staining, respectively.

CONCLUSIONS

This study provides detailed anatomical insights into the motor branches of the radial nerve to the Ba, Br, and ECRL muscles.

CLINICAL RELEVANCE

Understanding the anatomy of the radial nerve branches at the elbow is of utmost importance when devising a reconstructive strategy for upper limb paralysis. These findings can guide surgeons in selecting appropriate donor or recipient nerves for nerve transfer in cases of high tetraplegia and lower-type brachial plexus injuries.

Anatomical study of first palmar intermetacarpal flap in cadavers and application for congenital first web contracture in a child with Apert's syndrome

INTRODUCTION

Reconstructing severe first web contractures often involves using either pedicled forearm flaps, which can cause extensive scarring, or free flaps, which can be highly complex. In this study, we present a local palmar hand flap that overcomes both of these challenges.

METHODS

Ten fresh upper limbs were examined after arterial injection with colored latex. The study focused on identifying the most distal palmar vascular cutaneous branches suitable for designing an elliptical cutaneous flap over the volar intermetacarpal area. This flap's width was approximately 50% of the width of the thenar eminence. Additionally, we present the case of an 8-year-old child with a type 1 Upton's Apert's hand, which exhibited a severe first web contracture.

RESULTS

In seven cadaver hands, one distal cutaneous perforator was found, while in three hands, two perforators were identified. These perforators originated from the thumb radial collateral artery six times, pollex princeps three times, index radial collateral vessels twice, and thumb ulnar collateral vessels twice. The mean perforator diameter was 0.5 mm (ranging from 0.4 to 0.6 mm), and the mean perforator length was 10 mm (ranging from 0.8 to 12 mm). Using this flap bilaterally in our patient resulted in a straightforward procedure that created a broad and functional first web. A total-thickness skin graft was necessary to cover the proximal thenar area, and fortunately, no complications arose. A wide first web with an intermetacarpal angle of 40° ultimately was obtained scoring 8 on the kapandji.

CONCLUSIONS

The first palmar intermetacarpal flap presents itself as a reasonable and uncomplicated option for addressing significant moderate-to-severe first web contractures.

Shoulder extension impairment with residual neonatal brachial plexus injury

BACKGROUND

Impairment of both shoulder extension and behind-the-back function are common in patients with residual neonatal brachial plexus injury (NBPI), but have scarcely been studied or reported in the literature. Behind-the-back function is classically evaluated using the hand-to-spine task used for the Mallet score. Angular measurements of shoulder extension with residual NBPI have generally been studied utilizing kinematic motion laboratories. To date, no validated clinical examination method for this has been described.

METHODS

Intraobserver and interobserver reliability analyses of 2 shoulder extension angles-passive glenohumeral extension (PGE) and active shoulder extension (ASE)-were performed. Afterwards, a retrospective clinical study was conducted on prospectively collected data on 245 children with residual BPI treated from January 2019 through August 2022. Demographic characteristics, level of palsy, previous surgical procedures, modified Mallet score, and bilateral PGE and ASE data were analyzed.

RESULTS

All inter- and intraobserver agreements were excellent, ranging from 0.82 to 0.86. The median patient age was 8.1 years (3.5-21). Among the 245 children, 57.6% had Erb's palsy, 28.6% extended Erb's palsy, and 13.9% global palsy. One hundred sixty-eight (66%) of the children could not touch their lumbar spine, among whom 26.2% (n = 44) had to swing the arm to reach it. Both the degrees of ASE and PGE achieved correlation significantly with the hand-to-spine score, the ASE strongly (r = 0.705) and the PGE weakly (r = 0.372) (both P < .0001). Significant correlations also were found between lesion level and the hand-to-spine Mallet score (r = -0.339; P < .0001) and ASE (r = -0.299; P < .0001), and between patient age and the PGE (P = .0416, r = -0.130). A statistically significant decrease in PGE and incapacity to reach the spine were found in patients who underwent glenohumeral reduction, shoulder tendon transfer, or humeral osteotomy, relative to those who had microsurgery or no surgery. Receiver operating curves showed that, for both PGE and ASE, the minimum extension angle required to successfully perform the hand-to-spine task was 10°, with sensitivity levels of 69.9 and 82.2, and specificity levels of 69.5 and 87.8 (both P < .0001), respectively.

CONCLUSIONS

Glenohumeral flexion contracture and lost ASE are extremely common in children with residual NBPI. Both the PGE and ASE angles can be measured reliably with a clinical exam, with at least 10° of PGE and ASE necessary to perform the hand-to-spine Mallet task.

Extensor carpi radialis brevis motor branch transfer to the deep branch of the ulnar nerve to repair intrinsic hand palsy in neonatal lower brachial plexus and spinal cord injury: A case report

Concomitant lower neonatal brachial plexus palsy (Klumpke) and spinal cord injury is extremely rare but with a clearly established mechanism of injury pattern. No successful surgical techniques have been reported to date to restore intrinsic hand function. We report a case of successful transfer of the extensor carpi radialis brevis motor branch to the deep branch of the ulnar nerve to repair intrinsic hand palsy. Three-month-old boy with the diagnosis of left Klumpke paralysis and thoracic spinal cord injury associating left Horner's sign, intrinsic minus deformity of all the digits, and thenar muscle paralysis in the upper limb. Both lower limbs were fully paralyzed. Cervical magnetic resonance imaging (MRI) revealed spinal cord narrowing from T1 to T5 and pseudo-meningoceles involving the left C8 through T3 roots. Since no spontaneous recovery was apparent by 6.5 months and surgical exploration showed pronator quadratus denervation, the ECRB motor branch deep branch was transferred to the ulnar nerve (DBUN) with interposed a 7.5 cm-long sural nerve graft. By 18 months post-operatively, all the digits showed complete active IP extension. Thirty-six months after surgery, no signs of first dorsal interosseous nerve or thenar muscle reinnervation were present, thus an extensor carpi ulnaris opponensplasty was performed. ECRB motor branch might be a valuable tool to restore finger intrinsic function in these uncommon cases.