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

OBJECTIVE: 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. METHODS: 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. RESULTS: 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.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. CONCLUSIONS: The distal PT motor branch is suitable for reinnervation of the ECRB in radial nerve paralysis, for as long as 7-12 months postinjury.

Nerve transfers in the upper extremity following cervical spinal cord injury. Part 1: Systematic review of the literature.

OBJECTIVE: Patients with cervical spinal cord injury (SCI)/tetraplegia consistently rank restoring arm and hand function as their top functional priority to improve quality of life. Motor nerve transfers traditionally used to treat peripheral nerve injuries are increasingly being used to treat patients with cervical SCIs. In this study, the authors performed a systematic review summarizing the published literature on nerve transfers to restore upper-extremity function in tetraplegia. METHODS: A systematic literature search was conducted using Ovid MEDLINE 1946-, Embase 1947-, Scopus 1960-, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and clinicaltrials.gov to identify relevant literature published through January 2019. The authors included studies that provided original patient-level data and extracted information on clinical characteristics, operative details, and strength outcomes after nerve transfer procedures. Critical review and synthesis of the articles were performed. RESULTS: Twenty-two unique studies, reporting on 158 nerve transfers in 118 upper limbs of 92 patients (87 males, 94.6%) were included in the systematic review. The mean duration from SCI to nerve transfer surgery was 18.7 months (range 4 months-13 years) and mean postoperative follow-up duration was 19.5 months (range 1 month-4 years). The main goals of reinnervation were the restoration of thumb and finger flexion, elbow extension, and wrist and finger extension. Significant heterogeneity in transfer strategy and postoperative outcomes were noted among the reports. All but one case report demonstrated recovery of at least Medical Research Council grade 3/5 strength in recipient muscle groups; however, there was greater variation in the results of larger case series. The best, most consistent outcomes were demonstrated for restoration of wrist/finger extension and elbow extension. CONCLUSIONS: Motor nerve transfers are a promising treatment option to restore upper-extremity function after SCI. Flexor reinnervation strategies show variable treatment effect sizes; however, extensor reinnervation may provide more consistent, meaningful recovery. Despite numerous published case reports describing good patient outcomes with nerve transfers, there remains a paucity in the literature regarding optimal timing and long-term clinical outcomes with these procedures.

Nerve transfers in the upper extremity following cervical spinal cord injury. Part 2: Preliminary results of a prospective clinical trial.

OBJECTIVE: Patients with cervical spinal cord injury (SCI)/tetraplegia consistently rank restoring arm and hand function as their top functional priority to improve quality of life. Motor nerve transfers traditionally used to treat peripheral nerve injuries are increasingly used to treat patients with cervical SCIs. In this article, the authors present early results of a prospective clinical trial using nerve transfers to restore upper-extremity function in tetraplegia. METHODS: Participants with American Spinal Injury Association (ASIA) grade A-C cervical SCI/tetraplegia were prospectively enrolled at a single institution, and nerve transfer(s) was performed to improve upper-extremity function. Functional recovery and strength outcomes were independently assessed and prospectively tracked. RESULTS: Seventeen participants (94.1% males) with a median age of 28.4 years (range 18.2-76.3 years) who underwent nerve transfers at a median of 18.2 months (range 5.2-130.8 months) after injury were included in the analysis. Preoperative SCI levels ranged from C2 to C7, most commonly at C4 (35.3%). The median postoperative follow-up duration was 24.9 months (range 12.0-29.1 months). Patients who underwent transfers to median nerve motor branches and completed 18- and 24-month follow-ups achieved finger flexion strength Medical Research Council (MRC) grade ≥ 3/5 in 4 of 15 (26.7%) and 3 of 12 (25.0%) treated upper limbs, respectively. Similarly, patients achieved MRC grade ≥ 3/5 wrist flexion strength in 5 of 15 (33.3%) and 3 of 12 (25.0%) upper limbs. Among patients who underwent transfers to the posterior interosseous nerve (PIN) for wrist/finger extension, MRC grade ≥ 3/5 strength was demonstrated in 5 of 9 (55.6%) and 4 of 7 (57.1%) upper limbs 18 and 24 months postoperatively, respectively. Similarly, grade ≥ 3/5 strength was demonstrated in 5 of 9 (55.6%) and 4 of 7 (57.1%) cases for thumb extension. No meaningful donor site deficits were observed. Patients reported significant postoperative improvements from baseline on upper-extremity-specific self-reported outcome measures. CONCLUSIONS: Motor nerve transfers are a promising treatment option to restore upper-extremity function after SCI. In the authors' experience, nerve transfers for the reinnervation of hand and finger flexors showed variable functional recovery; however, transfers for the reinnervation of arm, hand, and finger extensors showed a more consistent and meaningful return of strength and function.

Nerve transfers for restoration of finger flexion in patients with tetraplegia.

OBJECTIVE The purpose of this paper was to report the authors' results with finger flexion restoration by nerve transfer in patients with tetraplegia. METHODS Surgery was performed for restoration of finger flexion in 17 upper limbs of 9 patients (8 male and 1 female) at a mean of 7.6 months (SD 4 months) after cervical spinal cord injury. The patients' mean age at the time of surgery was 28 years (SD 15 years). The motor level according to the ASIA (American Spinal Injury Association) classification was C-5 in 4 upper limbs, C-6 in 10, and C-7 in 3. In 3 upper limbs, the nerve to the brachialis was transferred to the anterior interosseous nerve (AIN), which was separated from the median nerve from the antecubital fossa to the midarm. In 5 upper limbs, the nerve to the brachialis was transferred to median nerve motor fascicles innervating finger flexion muscles in the midarm. In 4 upper limbs, the nerve to the brachioradialis was transferred to the AIN. In the remaining 5 upper limbs, the nerve to the extensor carpi radialis brevis (ECRB) was transferred to the AIN. Patients were followed for an average of 16 months (SD 6 months). At the final evaluation the range of finger flexion and strength were estimated by manual muscle testing according to the British Medical Research Council scale. RESULTS Restoration of finger flexion was observed in 4 of 8 upper limbs in which the nerve to the brachialis was used as a donor. The range of motion was incomplete in all 5 of these limbs, and the strength was M3 in 3 limbs and M4 in 1 limb. Proximal retrograde dissection of the AIN was associated with better outcomes than transfer of the nerve to the brachialis to median nerve motor fascicles in the arm. After the nerve to the brachioradialis was transferred to the AIN, incomplete finger flexion with M4 strength was restored in 1 limb; the remaining 3 limbs did not show any recovery. Full finger flexion with M4 strength was demonstrated in all 5 upper limbs in which the nerve to the ECRB was transferred to the AIN. No functional downgrading of elbow flexion or wrist extension strength was observed. CONCLUSIONS In patients with tetraplegia, finger flexion can be restored by nerve transfer. Nerve transfer using the nerve to the ECRB as the donor nerve produced better recovery of finger flexion in comparison with nerve transfer using the nerve to the brachialis or brachioradialis.

Results of nerve grafting in radial nerve injuries occurring proximal to the humerus, including those within the posterior cord.

OBJECT Results of radial nerve grafting are largely unknown for lesions of the radial nerve that occur proximal to the humerus, including those within the posterior cord. METHODS The authors describe 13 patients with proximal radial nerve injuries who were surgically treated and then followed for at least 24 months. The patients' average age was 26 years and the average time between accident and surgery was 6 months. Sural nerve graft length averaged 12 cm. Recovery was scored according to the British Medical Research Council (BMRC) scale, which ranges from M0 to M5 (normal muscle strength). RESULTS After grafting, all 7 patients with an elbow extension palsy recovered elbow extension, scoring M4. Six of the 13 recovered M4 wrist extension, 6 had M3, and 1 had M2. Thumb and finger extension was scored M4 in 3 patients, M3 in 2, M2 in 2, and M0 in 6. CONCLUSIONS The authors consider levels of strength of M4 for elbow and wrist extension and M3 for thumb and finger extension to be good results. Based on these criteria, overall good results were obtained in only 5 of the 13 patients. In proximal radial nerve lesions, the authors now advocate combining nerve grafts with nerve or tendon transfers to reconstruct wrist, thumb, and finger extension.

Results of wrist extension reconstruction in C5-8 brachial plexus palsy by transferring the pronator quadratus motor branch to the extensor carpi radialis brevis muscle.

OBJECT The objective of this study was to report the results of pronator quadratus (PQ) motor branch transfers to the extensor carpi radialis brevis (ECRB) motor branch to reconstruct wrist extension in C5-8 root lesions of the brachial plexus. METHODS Twenty-eight patients, averaging 24 years of age, with C5-8 root injuries underwent operations an average of 7 months after their accident. In 19 patients, wrist extension was impossible at baseline, whereas in 9 patients wrist extension was managed by activating thumb and wrist extensors. When these 9 patients grasped an object, their wrist dropped and grasp strength was lost. Wrist extension was reconstructed by transferring the PQ motor to the ECRB motor branch. After surgery, patients were followed for at least 12 months, with final follow-up an average of 22 months after surgery. RESULTS Successful reinnervation of the ECRB was demonstrated in 27 of the 28 patients. In 25 of the patients, wrist extension scored M4, and in 2 it scored M3. CONCLUSIONS In C5-8 root injuries, wrist extension can be predictably reconstructed by transferring the PQ motor branch to reinnervate the ECRB.

Results of nerve grafting in radial nerve injuries occurring proximal to the humerus, including those within the posterior cord.

OBJECTIVE Results of radial nerve grafting are largely unknown for lesions of the radial nerve that occur proximal to the humerus, including those within the posterior cord. METHODS The authors describe 13 patients with proximal radial nerve injuries who were surgically treated and then followed for at least 24 months. The patients' average age was 26 years and the average time between accident and surgery was 6 months. Sural nerve graft length averaged 12 cm. Recovery was scored according to the British Medical Research Council (BMRC) scale, which ranges from M0 to M5 (normal muscle strength). RESULTS After grafting, all 7 patients with an elbow extension palsy recovered elbow extension, scoring M4. Six of the 13 recovered M4 wrist extension, 6 had M3, and 1 had M2. Thumb and finger extension was scored M4 in 3 patients, M3 in 2, M2 in 2, and M0 in 6. CONCLUSIONS The authors consider levels of strength of M4 for elbow and wrist extension and M3 for thumb and finger extension to be good results. Based on these criteria, overall good results were obtained in only 5 of the 13 patients. In proximal radial nerve lesions, the authors now advocate combining nerve grafts with nerve or tendon transfers to reconstruct wrist, thumb, and finger extension.