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Background: Functional recovery following supinator motor branch transfer requires further investigation., Objective: To compare the outcome of finger extension after supinator motor branch transfer or contralateral C7 (cC7) transfer in C7-T1 brachial plexus palsies in rats., Methods: In this study, 120 adult rats underwent C7-T1 nerve root avulsion and received different nerve transfer repairs: group A, cC7 nerve transfer to the lower trunk; group B, supinator motor branch nerve transfer to the posterior interosseous nerve (PIN); and group C, no repair. The ethology of the rats, latency and amplitude of the compound muscle action potential from the PIN, muscle mass and muscle fiber cross-sectional area of the extensor digitorum communis and extensor carpi ulnaris, and number of myelinated nerve fibers in the PIN were examined postoperatively., Results: There was no finger extension in group C. We observed finger extension in groups A and B 50.2 ± 5.66 and 13.1 ± 2.08 days postoperatively, respectively. Finger extension restoration in group B was greater than that in group A at 4, 8, and 12 weeks postoperatively ( P < .05). Sixteen weeks after surgery, the recovery rate of the myelinated nerve fibers in group A was marginally higher than that in group B, but the difference was not significant. Of the other measured values, group B showed a greater and significant improvement compared to group A ( P < .05)., Conclusion: Supinator motor branch transfer allows for faster recovery and is a more effective procedure for restoring finger extension in C7-T1 brachial plexus palsies., (Copyright © 2017 by the Congress of Neurological Surgeons)

In obstetric brachial plexus palsy (OBPP), irreversible muscle atrophy occurs much faster in intrinsic muscles of the hand than in the biceps. To elucidate the mechanisms involved, mRNA expression profiles of denervated intrinsic muscles of the forepaw (IMF) and denervated biceps were determined by microarray using the rat model of OBPP where atrophy of IMF is irreversible while atrophy of biceps is reversible. Relative to contralateral control, 446 dysregulated mRNAs were detected in denervated IMF and mapped to 51 KEGG pathways, and 830 dysregulated mRNAs were detected in denervated biceps and mapped to 52 KEGG pathways. In denervated IMF, 10 of the pathways were related to muscle regulation; six with down-regulated and one with up-regulated mRNAs. The remaining three pathways had both up- and down-regulated mRNAs. In denervated biceps, 13 of the pathways were related to muscle regulation, six with up-regulated and seven with down-regulated mRNAs. Five of the pathways with up-regulated mRNAs were related to regrowth and differentiation of muscle cells. Among the 23 pathways with dysregulated mRNAs, 13 were involved in regulation of neuromuscular junctions. Our results demonstrated that mRNAs expression characteristics in irreversibly atrophic denervated IMF were different from those in reversibly atrophic denervated biceps; dysregulated mRNAs in IMF were associated with inactive pathways of muscle regulation, and in biceps they were associated with active pathways of regrowth and differentiation. Lack of self-repair potential in IMF may be a major reason why atrophy of IMF becomes irreversible much faster than atrophy of biceps after denervation.

Contralateral C7 (CC7) neurotization has been an important approach for brachial plexus injury (BPI). Patients can achieve relatively good grasping function driven by the proximal extrinsic hand muscle (flexor digitorum, FD) after CC7 neurotization, whereas the thumb opposition function driven by the distal intrinsic muscle (abductor pollicis brevis, APB) is poor. The present study aimed to investigate the brain reorganization patterns of the recovery processes of intrinsic and extrinsic hand functions after repairing the median nerve by CC7 neurotization. Transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) were used to evaluate the cerebral plasticity in one BPI patient after CC7 neurotization. After the CC7 neurotization, the patient showed improvements in the paralyzed hand. Combination of TMS and fMRI investigations demonstrated different cortical reshaping patterns of APB and FD. It was also found that the activated cortical areas of FD were located in bilateral motor cortices, but the area of APB was only located in ipsilateral motor cortex. The cerebral plasticity procedure appeared to be different in the gross and fine motor function recovery processes. It provided a new perspective into the cerebral plasticity induced by CC7 neurotization., (Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.)

Clinically in obstetric brachial plexus palsy (OBPP), irreversible atrophy of intrinsic musculature of the hand in denervation occurs much earlier than that of denervated arm muscles. With the aim of finding clues to explain this, the miRNA expression profile of denervated intrinsic musculature of the forepaw (IMF) and that of the denervated biceps were examined by microarray screening in the rat model simulating irreversible muscular atrophy caused by pan-plexus lesions of OBPP, and potential targets of specifically dysregulated miRNAs were predicted with use of bioinformatics analysis. It was found that denervated IMF and biceps had their own specifically dysregulated miRNAs, respectively, as compared with control. Analysis of Gene Ontology and of pathway showed that those specifically dysregulated miRNAs and their target genes might participate in self-regulation of neuromuscular junctions (NMJs). These outcomes suggest that self-regulative mechanism of NMJs may be different between denervated IMF and denervated biceps in the rat model simulating irreversible muscular atrophy of OBPP., (Copyright © 2015 Elsevier B.V. All rights reserved.)

To elucidate anatomic basis of susceptibility for contracture of the subscapularis muscle in Erb's palsy of the brachial plexus, we semiquantitatively studied the spinal nerve origins of the subscapular nerves innervating the subscapularis, with special reference to the contribution of C7 innervation to the subscapularis. Thirty-three sides of formalin-fixed upper extremities were dissected to obtain the intact brachial plexus. After immersed in 10% acetic acid for 2 weeks, the upper and lower subscapular nerves innervating the whole subscapularis, were dissected retrogradely to verify their spinal nerve origins. The cross-sectional area by C7 innervation and that by the upper trunk innervation was calculated respectively to obtain the constituent percentage of different components in the upper and lower subscapular nerves. In the upper subscapular nerve, fascicles of C7 accounted for 0% (interquartile range, 0-1.1%) of cross-sectional area and those of the upper trunk, 100% (98.9-100%). In the lower subscapular nerve, fascicles of C7 accounted for 40.5% (23.5-47.5%) and those of the upper trunk, 59.5% (52.5-76.5%). In total, 18.6% (13.3-27.3%) of fascicles in the subscapular nerves innervating the subscapularis originated from C7, while 81.4% (72.7-86.7%) of those came from the upper trunk. It is confirmed that innervation of the subscapularis originates from more spinal cord segments than that of infraspinatus and teres minor, and this may be the main reason for which in Erb's palsy, functional recovery of the subscapularis is often faster than that of lateral rotators of the shoulder, resulting in medial rotation contracture of the shoulder., (Copyright © 2012 Wiley Periodicals, Inc.)

There are no biological marks to indicate if denervated muscle atrophy after nerve injury is irreversible. Clinically in obstetric brachial plexus palsy (OBPP), atrophy of denervated intrinsic musculature of the hand is much faster to irreversible than that of denervated muscles of the arm. 64 pup rats whose C5C6 had been divided and C7C8T1 avulsed, were divided equally into the reconstruction and control groups. The former had subgroups R1, R5, R10, R15 where the ulnar and musculocutaneous nerves were reconstructed one, five, ten and 15 weeks respectively after injury and efficacy was evaluated 12 weeks later. The latter had C1, C5, C10, C15 subgroups where denervated muscles of the two nerves were assessed one, five, ten and 15 weeks after injury. Results of average cross-sectional area of the muscle fiber for intrinsic musculature of the forepaw showed that the R5, R10, R15 subgroups were not statistically superior to the C5, C10, C15 ones, respectively, though R1 was; those for biceps indicated, however, that the R1, R5, R10 subgroups were better than the C1, C5, C10 ones, respectively, though R15 was not. In the reconstruction subgroups regenerative nerve fibers in each nerve were no less than 53 percent of those on the control side, while number of motor end plates was statistically less in subgroups with irreversible muscle atrophy. We conclude that rat model of OBPP is suitable for simulating clinical appearance of atrophy of denervated intrinsic musculature of the hand being faster than that of denervated muscles of the arm.

Background: In injuries of the lower brachial plexus, finger flexion can be restored by nerve or tendon transfer. However, there is no technique that can guarantee good recovery of finger and thumb extension., Objective: To determine the spinal nerve origins of the muscular branches of the radial nerve and identify potential intraplexus donor nerves for neurotization of the posterior interosseous nerve in patients with lower brachial plexus injuries., Methods: An intraoperative electrophysiological study was carried out during 16 contralateral C7 nerve transfers. The compound muscle action potential of each muscle innervated by the radial nerve was recorded while the C5-T1 nerves were individually stimulated., Results: The triceps brachii muscle primarily received root contributions from C7. The C5 and C6 nerve roots displayed greater amplitudes for the brachioradialis and supinator muscles compared with those of the C7, C8, and T1 nerve roots (P < .05). The extensor carpi radialis branch was innervated by C5, C6, and C7, and no significant differences were detected between them (P > .05). The amplitudes obtained for the extensor digitorum communis branch were the largest from C7 and C8, without a significant difference between them (P > .05), whereas the amplitudes of the extensor carpi ulnaris and extensor pollicis longus were largest from the C8 root (P < .05)., Conclusion: The supinator muscle branch is likely the best donor nerve for the repair of lower brachial plexus injuries affecting muscles that are innervated by the posterior interosseous nerve.

An experimental study was conducted to observe the electrophysiologic changes in C7 innervated muscles following transection of different fascicles of C7 nerve root in the brachial plexus with already transected C5 and C6. Twenty-four Sprague-Dawley rats were randomized into groups A, B, and C. C5 and C6 transection, C5, C6, and partial C7 (anteriolateral fascicles of the anterior division) transection, and C5, C6, and C7 transection were done in group A, B, and C, respectively. One month postoperatively, compound muscle action potentials of the latissimus dorsi, triceps, and extensor digitorum communis were recorded. Decreased amplitude and a prolonged latent period were seen in all three muscles of group C. No obvious changes, however, were found in groups A and B. This suggests that when the upper trunk of the brachial plexus is injured, partial transection of C7 does not obviously impair C7 innervated muscle function. Selective ipsilateral C7 transfer is safe for the treatment of upper-trunk avulsion., (Copyright 2004 Wiley-Liss, Inc.)

Objective: To study the influence of the electric stimulation of denervated muscle atrophy., Methods: Sixteen SD rats were made the model of denervated skeletal muscle in two lower limbs by cutting off the sciatic nerve and femoral nerve. The right gastrocnemius muscle was stimulated with JNR-II nerve & muscle recovery instrument by skin as the experimental side and the left was not treated as the control side. The muscle histology, ultrastructure, fibrillation potential amplitude, Na(+)-K(+)-ATPase and Ca(2+)-ATPase activities were observed 2 weeks and 4 weeks after operation., Results: Electric stimulation could protect mitochondria and sarcoplasmic reticulum from the degeneration. The reduction rates of muscle cell diameter and cross section in the experimental side were slower significantly than those in control side. There was no influence on fibrillation potential amplitude in the both sides after electric stimulation. The reduction rates of Na(+)-K(+)-ATPase activity in the experimental side were slower 15.59% and 27.38% respectively than those in the control side. The reduction rates of Ca(2+)-ATPase activity in the experimental side were slower 4.83% and 21.64% respectively than those in the control side., Conclusion: The electric stimulation can protect muscle histology, electrophysiology and enzymic histochemistry of denervated skeletal muscle from the degeneration. The electric stimulation is an effective method to prevent and treat muscle atrophy.

To evaluate the effects of transfer of the trapezius and/or latissimus dorsi with the teres major for treatment of dysfunction of the shoulder in obstetrical brachial plexus palsy (OBPP), 34 patients with paresis of the abductors and external rotators, as well as co-contraction of the adductors in abduction, who had undergone reconstructive operations, were followed-up for at least 1 year. Of these, transfer of the latissimus dorsi with attached teres major to the insertion of the infraspinatus (single procedure), was performed in 25 cases, and transfer of both latissimus dorsi with teres major and trapezius (to the humerus) in nine (combined procedure). Gilbert's grading system was used for evaluation. The results showed that in spite of improvement of external rotation in most of the cases, abduction was improved in only 13 of the 25 cases with a single procedure, and that eight of nine cases with a combined procedure gained improvement of both external rotation and abduction. These results indicated that, for improvement of both abduction and external rotation of the shoulder in OBPP, transfer of the latissimus dorsi with the teres major can be performed only when abduction is > or =90 degrees; otherwise, transfer of the trapezius should be added.