Distal pronator teres motor branch transfer for wrist extension restoration in radial nerve paralysis

Abstract

<jats:sec><jats:title>OBJECTIVE</jats:title><jats:p>The authors describe the anatomy of the motor branches of the pronator teres (PT) as it relates to transferring the nerve of the extensor carpi radialis brevis (ECRB) to restore wrist extension in patients with radial nerve paralysis. They describe their anatomical cadaveric findings and report the results of their nerve transfer technique in several patients followed for at least 24 months postoperatively.</jats:p></jats:sec><jats:sec><jats:title>METHODS</jats:title><jats:p>The authors dissected both upper limbs of 16 fresh cadavers. In 6 patients undergoing nerve surgery on the elbow, they dissected the branches of the median nerve and confirmed their identity by electrical stimulation. Of these 6 patients, 5 had had a radial nerve injury lasting 7–12 months, underwent transfer of the distal PT motor branch to the ECRB, and were followed for at least 24 months.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>The PT was innervated by two branches: a proximal branch, arising at a distance between 0 and 40 mm distal to the medial epicondyle, responsible for PT superficial head innervation, and a distal motor branch, emerging from the anterior side of the median nerve at a distance between 25 and 60 mm distal to the medial epicondyle. The distal motor branch of the PT traveled approximately 30 mm along the anterior side of the median nerve; just before the median nerve passed between the PT heads, it bifurcated to innervate the deep head and distal part of the superficial head of the PT. In 30% of the cadaver limbs, the proximal and distal PT branches converged into a single trunk distal to the medial epicondyle, while they converged into a single branch proximal to it in 70% of the limbs. The proximal and distal motor branches of the PT and the nerve to the ECRB had an average of 646, 599, and 457 myelinated fibers, respectively.</jats:p><jats:p>All patients recovered full range of wrist flexion-extension, grade M4 strength on the British Medical Research Council scale. Grasp strength recovery achieved almost 50% of the strength of the contralateral side. All patients could maintain their wrist in extension while performing grasp measurements.</jats:p></jats:sec><jats:sec><jats:title>CONCLUSIONS</jats:title><jats:p>The distal PT motor branch is suitable for reinnervation of the ECRB in radial nerve paralysis, for as long as 7–12 months postinjury.</jats:p></jats:sec>

Innervation Patterns of the Pronator Teres Muscle and Their Possible Role in Neurotization: A Systematic Review of Cadaveric Studies

“…Our analysis on the above compatibilities further supported by a recent histomorphometric study, wherein, the PTM branches are seen to have an average of 646 and 599 myelinated fibers in both proximal and distal branches, respectively. These myelinated fibers are more or less close to the 548 and 457 fibers of ECRB reported (9,31). The above comparison of diameter differences and nerve fibers might give an explicit idea about selecting the donor nerve for neurotization procedures.…”

“…Contrary to the classic description, many recent studies have reported variability in the motor branches of Mn that are supplying PTM. And these branches are located at a variable distance either proximal or distal to the humeral intercondylar line (HIL) or at the level of HIL (4)(5)(6)(7)(8)(9). In cases, where more than one branch to the PTM is present, these remain as an effective alternative surgical option for nerve transfer procedures (5,8,10,11).…”

Patterns of median nerve branching in the cubital fossa: implications for nerve transfers to restore motor function in a paralyzed upper limb

“…The DPT consistently ran along the top of the median nerve to reach the deep head of the PT, as previously reported. 9 Yang et al 13 described the presence of at least 2 branches to the PT, whereas Tung and Mackinnon 6 described 2 branches in only 70% of their cases. The FCR motor branch originated just distal to the PPT (45%), from the DPT motor branch (20%), or just proximal to the AIN or from the AIN (35%).…”

“…In this last scenario, if the DPT is chosen as a donor for restoration of wrist extension in a patient with radial nerve paralysis, the DPT should be harvested distal to the FCR motor branch. 9 Proximal to the PT muscle, identification of the FCR motor branch requires confirmation by electrical stimulation. Distal to the PT muscle, identification can be confirmed by locating its motor entry point.…”

“…Interest in the surgical anatomy of the median nerve in the cubital fossa applies to nerve transfer to achieve hand function restoration for radial, high median nerve, brachial plexus, and spinal cord injuries. 1,[6][7][8][9] With some peripheral nerve injuries and peripheral types of spinal cord injury, recipient nerves will not respond to intraoperative electrical stimulation; instead, their identification relies exclusively on anatomical knowledge.…”