The Study of Myogenin Expression in Denervated Human Skeletal Muscles

Skeletal muscle denervation eventually causes atrophy as a result of interrupted nerve conduction and the lack of nutritional factors. Myogenin is a myogenic regulatory factor that plays a key role in myoblast differentiation. Changes in myogenin expression in denervated rat skeletal muscle have been demonstrated, but myogenin expression in denervated human skeletal muscle has not been reported. Human muscle samples were analysed at different time-points post-denervation to evaluate changes in myogenin expression and their relationship with skeletal muscle atrophy. Post-denervation, myogenin mRNA levels peaked at 7 months and were 37.5 times the normal level. Expression levels then declined to 21 and 11 times the normal level at 12 and 26 months post-denervation, respectively. Prolonged denervation resulted in pathological changes characterized by decreased numbers of intact muscle fibres.

Regenerated host axons form synapses with neurons derived from neural stem cells transplanted into peripheral nerves

It is reported that neural stem cells (NSC) can arrest denervated muscle atrophy and promote nerve regeneration when transplanted into injured peripheral nerves, and that regenerated host axons can form synapses with transplanted and differentiated NSC. In this study, F344 rat nerve segments and F344 rat NSC were transplanted into host green fluorescence protein (GFP) transgenic F344 rats. This allowed transplanted F344 rat tissue to be used as a nonluminous background for the clear visualization of regenerated host GFP axons. Regenerated host axons grew into the transplanted F344 nerve segment 2 weeks after nerve anastomosis. Immunohistochemical staining and confocal microscope analysis revealed that regenerated host axons formed synapses with NSC-derived neurons. The findings confirmed that regenerated peripheral axons form synapses with neurons in peripheral nerves, possibly forming the basis for clinical application in peripheral nerve injury.

Reinnervation of thenar muscle after repair of total brachial plexus avulsion injury with contralateral C7 root transfer: report of five cases

OBJECTIVE

In this report, we present the findings of reinnervation of the thenar muscle in five patients who underwent the contralateral C7 nerve root transfers for repair of total brachial plexus root avulsions.

PATIENTS AND METHODS

Five (2 children and 3 adults) of 32 patients who received two-staged procedures of the contralateral C7 nerve root transfers to the median nerves showed reinnervation of thenar muscle were evaluated. The patients also received other procedures including the intercostal nerve transfer to the musculocutaneous nerve, the spinal accessory nerve to the suprascapular nerve, and the ipsilateral phrenic nerve to the musculocutaneous nerve before the contralateral C7 nerve root transfers. The patients were followed up from 24 to 118 months after surgery.

RESULTS

Varied degrees of functional restorations were achieved after different procedures. The strength of abductor pollicis brevis (APB) muscle with Grade M2 was found in four patients. The incomplete interference pattern in the APB muscle was detected by electromyogram (EMG) in two patients, and the minority motor unit potential (MUP) was detected in other two patients. The strength of APB muscle was found with Grade M1 in one patient with EMG showing MUP.

CONCLUSION

The findings from our series show reinnervation of thenar muscles after repair of the median nerve with the contralateral C7 nerve root transfer, which provides evidence for further investigation of reconstruction of the brachial plexus root avulsion injury with this procedure.

Reorganization in motor cortex after brachial plexus avulsion injury and repair with the contralateral C7 root transfer in rats

The purpose of our study was to establish the profile of cortical reorganization in whole BPAI on rats and evaluate changes of cortical reorganization after repair of the median nerve with the contralateral C7 root transfer. Forty adult SD rats underwent whole roots avulsion of left brachial plexus, among them 20 received contralateral C7 root transfer to the injured median nerve. Intracortical microstimulation was performed in primary motor cortex (M1) at intervals of 3, 5, 7, and 10 months, postoperatively. The maps of motor cortical responses were constructed. Five normal rats were used as the control. Results showed that stimulating right M1 elicited motion of left vibrissae, submaxilla, neck, back, and left hindlimb after left BPAI, among them neck representation area replaced the forelimb area throughout the reorganization process. The left forelimb representation area was found in the left motor cortex 5 months after the contralateral C7 root transfer and existed in both motor cortexes at 7th postoperative month. The left forelimb representation area was detected only in right motor cortex at 10th month, postoperatively. In conclusions, after the contralateral C7 root transfer for repair of the median nerve in BPAI, the cortical reorganization occurred in a time-dependent reorganization. The findings from this study demonstrate that brain involves in the functional recovery after BPAI and repair with nerve transfer and suggest that efforts to improve the results from nerve repair should address the peripheral nerve as well as the brain.

Phrenic nerve transfer for elbow flexion and intercostal nerve transfer for elbow extension

PURPOSE

To explore long-term recovery of elbow flexion and extension after transferring the phrenic nerve and intercostal nerves, respectively, in adults with global brachial plexus avulsion injuries.

METHODS

Seven adults with global brachial plexus avulsion injuries had the phrenic nerve transferred to the musculocutaneous nerve (or to the anterior division of upper trunk) and intercostal nerves transferred to the triceps branch of the radial nerve at our hospital 7 to 12 years ago. The results of elbow motor strength testing using the Medical Research Council grading scale, and electrodiagnostic findings using electromyogram examinations, were studied retrospectively. Pulmonary function tests were also performed at final visits.

RESULTS

Functional elbow flexion was obtained in most of the 7 cases (M2, 1; M3, 3; M4, 2; and M5, 1) but elbow extension was absent or insufficient in all subjects (M0, 1; M1, 3; and M2, 3). Electrical results showed successful biceps reinnervation in 6 patients and successful triceps reinnervation in 5. No patient experienced breathing problems, and pulmonary function results were within normal range.

CONCLUSIONS

In the long term, after brachial plexus avulsion injury in most patients who underwent both phrenic nerve and intercostal nerve transfer to achieve elbow flexion and extension eventually obtained satisfactory elbow flexion but poor elbow extension. We recommend against transferring the intercostal nerves to the triceps branch of radial nerve in conjunction with primary phrenic to musculocutaneous nerve transfer.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Long-range plasticity between intact hemispheres after contralateral cervical nerve transfer in humans

OBJECT

Peripheral nerve injury in a limb usually causes intrahemispheric functional reorganization of the contralateral motor cortex. Recently, evidence has been emerging for significant interhemispheric cortical plasticity in humans, mostly from studies of direct cortical damage. However, in this study, a long-range interhemispheric plasticity was demonstrated in adults with brachial plexus avulsion injury (BPAI) who had received a contralateral cervical nerve transfer, and this plasticity reversed the BPAI-induced intrahemispheric cortical reorganization.

METHODS

In this study, 8 adult male patients with BPAI were studied using PET scanning.

RESULTS

The results indicated that the right somatomotor cortices, which may contribute to the control of the injured limb before brachial plexus deafferentation, still played an important role when patients with BPAI tried to move their affected limbs, despite the fact that the contralateral C-7 nerve transfer had been performed and the peripheral output had changed dramatically. Such findings are consistent with the results of the authors' previous animal study.

CONCLUSIONS

The brain may try to restore the control of an injured limb to its original cortex area, and a complicated change of peripheral pathway also can induce long-range interhemispheric cortical reorganization in human motor cortex.

Clinical use of supinator motor branch transfer to the posterior interosseous nerve in C7–T1 brachial plexus palsies

Object

In C7–T1 brachial plexus palsies, finger extension and flexion are absent. At the authors' institution, finger flexion has been successfully reconstructed by transferring the brachialis motor branch to the anterior interosseous nerve. However, there is no reliable method for restoring finger extension. In the present study, the authors examined the surgical results of transferring the supinator motor branch to the posterior interosseous nerve.

Methods

Since October 2007, the authors have performed a supinator motor branch transfer to the posterior interosseous nerve in 4 patients. The patients underwent follow-up every 3–4 months postoperatively.

Results

Finger extension appeared between 5 and 9 months in the first 3 cases and demonstrated promising improvement over time. One recent case remains under follow-up.

Conclusions

A supinator motor branch to posterior interosseous nerve transfer leads to reliable recovery of thumb and finger extension. Therefore, it is a viable option for C7–T1 brachial plexus palsies.

Sympathetic preganglionic neurons project to superior cervical ganglion via C7 spinal nerve in pup but not in adult rats

We investigated the distribution of sympathetic preganglionic fibers in each spinal nerve of the brachial plexus, and its correlation with presence of Horner's syndrome in the pup and adult rats. According to surgical intervention to the C7-T1 spinal nerves in the right side, rats of 7 days postnatal (P7), P14 and adulthood (24 for each age group) were subdivided into four subgroups of six each, respectively, i.e., C7 or C8 or T1 spared subgroup--where C7 or C8 or T1 alone was kept intact with avulsion of the other two spinal nerves and division of the sympathetic chain caudal to the stellate ganglion; C7-T1 avulsed subgroup--where C7-T1 were all avulsed but the sympathetic chain kept intact. Fluoro-Gold (FG) was injected bilaterally into the superior cervical ganglion (SCG) for labeling of sympathetic preganglionic neurons (SPNs). Furthermore, Horner's syndrome was examined after avulsion of different spinal nerves for P14 and adult rats. In C7 spared subgroups, FG-labeled neurons accounted averagely for 16.9% in P7, 13.5 in P14 and 1.0 in adult rats, and difference was statistically significant between P7 and adults (Z=-2.9, P=0.004), P14 and adults (Z=-2.9, P=0.004). When both C7 and C8 were avulsed, Horner's syndrome was more prone to be produced in pups than in adults (chi(2)=4.2, P=0.04). These results indicate that some SPNs project to SCG via C7 in the pup, but this pathway disappears during postnatal development. It suggests that in newborns with brachial plexopathy, presence of Horner's syndrome may be correlated with avulsion of C7.

Surgical outcome of phrenic nerve transfer to the anterior division of the upper trunk in treating brachial plexus avulsion

Object

The purpose of this investigation was to study the surgical results of phrenic nerve transfer to the anterior division of the upper trunk of the brachial plexus.

Methods

Between 2002 and 2005, 40 patients received a phrenic nerve transfer to the anterior division of the upper trunk of the brachial plexus to restore elbow flexion. These cases were followed postoperatively for > 2 years, and the efficacy of the surgery and related factors were evaluated.

Results

The overall effective rate of this procedure was 82.5% (Medical Research Council Grade ≥ 3). The results show that for patients with surgical delay of > 1 year or prolongation of the latency of the preoperative phrenic nerve evoked potential > 20%, the recovery rates were 25 and 50%, respectively.

Conclusions

Phrenic nerve transfer to the anterior division of the upper trunk of the brachial plexus is a simple procedure that causes minor surgical trauma and yields good recovery of elbow flexion. It is suitable in patients with a relatively intact structure at the division level of the brachial plexus.

Computer simulation of stress distribution in the metatarsals at different inversion landing angles using the finite element method

Metatarsal fracture is one of the most common foot injuries, particularly in athletes and soldiers, and is often associated with landing in inversion. An improved understanding of deformation of the metatarsals under inversion landing conditions is essential in the diagnosis and prevention of metatarsal injuries. In this work, a detailed three-dimensional (3D) finite element foot model was developed to investigate the effect of inversion positions on stress distribution and concentration within the metatarsals. The predicted plantar pressure distribution showed good agreement with data from controlled biomechanical tests. The deformation and stresses of the metatarsals during landing at different inversion angles (normal landing, 10 degree inversion and 20 degree inversion angles) were comparatively studied. The results showed that in the lateral metatarsals stress increased while in the medial metatarsals stress decreased with the angle of inversion. The peak stress point was found to be near the proximal part of the fifth metatarsal, which corresponds with reported clinical observations of metatarsal injuries.

Hand prehension recovery after brachial plexus avulsion injury by performing a full-length phrenic nerve transfer via endoscopic thoracic surgery

Object

The functional recovery of hand prehension after complete brachial plexus avulsion injury (BPAI) remains an unsolved problem. The authors conducted a prospective study to elucidate a new method of resolving this injury.

Methods

Three patients with BPAI underwent a new procedure during which the full-length phrenic nerve was transferred to the medial root of the median nerve via endoscopic thoracic surgery support. All 3 patients were followed up for a postoperative period of > 3 years.

Results

The power of the palmaris longus, flexor pollicis longus, and the flexor digitorum muscles of all 4 fingers reached Grade 3–4/5, and no symptoms of respiratory insufficiency occurred.

Conclusions

Neurotization of the phrenic nerve to the medial root of the median nerve via endoscopic thoracic surgery is a feasible means of early hand prehension recovery after complete BPAI.

[An experimental study on outcome of ipsilateral C7 nerve root transfer to repair the root avulsion of the brachial plexus]

OBJECTIVE

To experimentally compare the treatment outcome of the injured upper limb of the root avulsion of C5 and C6 of the brachial plexus repaired by ipsilateral C7 nerve root transfer and other three multiple nerve transfers.

METHODS

One hundred and twenty SD rats of simulated C5 and C6 root avulsion randomly divided into 4 groups, and 30 each underwent various combined nerve transfers. Group A: the ipsilateral C7 root transferred to the upper trunk of brachial plexus and the spinal accessory nerve to the suprascapular nerve; Group B: partial fascicles of the ulnar nerve transferred to the biceps branch (Oberlin's procedure), the spinal accessory to the suprascapular and branches to the triceps long head to the axillary nerve; Group C: the phrenic transferred to the musculocutaneous, cervical plexus motor branches to the lower trunk (axillary nerve) of brachial plexus and the spinal accessory nerve to the suprascapular nerve; Group D: the phrenic transferred to the musculocutaneous and the spinal accessory nerve to the suprascapular nerve. Neurotization outcomes were evaluated at 3, 6 and 12 weeks postoperatively by comparing changes of behavioral tests (Ochiai clinical scores, Barth Foot-fault test and Terzis grooming test), neurophysiological investigations and muscular histology.

RESULTS

At 3 weeks after operation, no significant difference was found between Group A and other three control groups in the three behavioral evaluations. Neurophysiologic investigations of the axillary nerve showed that Group A was superior to the other three groups. Muscular histological outcome of the axillary nerve and deltoid muscle showed that Group A was superior to the Group C and D, while no significant difference was found between Group A and B. Except that the thruput of regenerating medullated musculocutaneous nerve fibers of Group A was superior to Group C, neurophysiological and histological outcome of the musculocutaneous nerve and biceps showed that no significant difference was found between Group A and other three groups. At 12 weeks postoperatively, nearly all the behavioral, neurophysiological and histological determination showed that Group A was superior to the other three groups.

CONCLUSIONS

Ipsilateral C7 transfer to the upper trunk of brachial plexus combined with the spinal accessory nerve to the suprascapular nerve is found to be significantly effective on treatment of the root avulsion of C5 and C6 of the brachial plexus.

ORIGINATION OF THE BRACHIALIS BRANCH OF THE MUSCULOCUTANEOUS NERVE

OBJECTIVE

To test an innovative method to study the origin of a specific nerve or of the nerve fibers innervating a given muscle on the healthy upper limb of a human being and to find the rationale for the brachialis branch of musculocutaneous nerve transfer.

METHODS

An intraoperative electrophysiological study was conducted comprising 27 cases of contralateral C7 transfer. The goal of the study was to record compound muscle action potential of the brachialis muscle while various nerve roots of the brachial plexus were stimulated.

RESULTS

Analysis of compound muscle action potential suggested that the brachialis branch of the musculocutaneous nerve is composed of fibers from the C5, C6, and C7 nerve roots and that the C5 and C6 nerve roots are the major origin for the brachialis branch of musculocutaneous nerve fibers.

CONCLUSION

The technique proposed here was a more direct and functional method of tracing the origin of a specific nerve or of the nerve fibers innervating a given muscle on the healthy upper limb of a live patient.

Contralateral C7 transfer for the treatment of brachial plexus root avulsions in children - a report of 12 cases

PURPOSE

To retrospectively determine the risks and benefits of contralateral C7 nerve root transfer in infants and children.

METHODS

In 12 infants and children with brachial plexus root avulsions from birth injury or other trauma, the common trunk of the contralateral C7 root was transferred to the trunk, division, cord, or nerve branch(es) on the affected side with 2 different types of interposition grafts. The surgery was performed in 1 stage for 5 patients and in 2 stages for 7 patients.

RESULTS

Patients were followed up for a mean of 42 months, with a minimum of 21 months. Noteworthy function (> or = M2+, modified British Medical Research Council grading system) was gained in 10 of 12 patients and sensory function (> or = S3, British Medical Research Council grading system) was gained in all patients. Improvements in strength and sensation were accompanied by little synchronous motion and sensibility changes in the donor limb in 7 children, to whom the repaired nerves were those innervating the shoulder and/or elbow or both the musculocutaneous and median nerves. In addition to slight damage to the sensory function of the median nerve, 2 infants also had temporarily reduced shoulder abduction on the healthy side.

CONCLUSIONS

For contralateral C7 transfer in infants and children with brachial plexus root avulsions, the deficit created by the procedure is minimal and motor and sensory function is gained. Transfer of the contralateral C7 root to different nerves for a child may improve the quality of functional recovery.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic, Level IV.

[Long-term impact of transfer of phrenic nerve on respiratory system of children: a clinical study of 34 cases]

OBJECTIVE

To study the long-term impact of transfer of phrenic nerve on respiratory system of children.

METHODS

Thirty-four children with brachial plexus injury, 25 boys and 9 girls, underwent transfer of phrenic nerve and were divided into 3 groups according to the age when they underwent operation: group of the age of 0 - 12 months (n = 17), group of 13 - 36 months (n = 11), and group of 37 - 60 months (n = 6). Thirty-four sex, height, and body weight-matched healthy children were used as controls. Follow-up, including physical examination, pulmonary function examination (tidal volume, ventilation, etc), blood gas analysis, and chest radiography, was conducted for 4.03 years (3 - 7 years).

RESULTS

The values of maximum vital capacity of the group of 0 - 12 months and group of 13 - 36 months were 1.0 L +/- 0.2 L and 1.2 L +/- 0.4 L, both significantly lower than those of the corresponding control groups (1.3 L +/- 0.3 L and 1.4 L +/- 0.5 L, both P < 0.05). The values of one-second vital capacity of the group of 0 - 12 months and group of 13 - 36 months were 0.8 L +/- 0.1 L and 0.9 L +/- 0.1 L, both significantly lower than those of the corresponding control groups (1.0 L +/- 0.1 L and 1.0 L +/- 0.1 L, both P < 0.05). However, the values of the maximum vital capacity and one-second vital capacity of the group of 37 - 60 months were 1.6 L +/- 0.3 L and 1.8 L +/- 0.5 L respectively, both not significantly different from those of the controls (both P > 0.05). The results of blood gas analysis of the 3 operation groups were not significantly different from those of the corresponding controls. Chest radiograph showed that the diaphragm top was raised by 1.93 intercostal spaces (0.5 - 3.5 intercostal spaces) in comparison with the contralateral sides with significant differences between the group of 0 - 12 months and the group of 13 - 36 months and between the group of 0 - 12 months and the group of 37 - 60 months (both P < 0.05). The recurrent respiratory infection rate and of the groups of 0 - 12 months and 13 - 36 months were 47.1% and 27.3% respectively, both significantly higher than that of the group of 37 - 60 months (0%). The thorax deformity rate of the groups of 0 - 12 months and 13 - 36 months were 41.2% and 9.1% respectively, both significantly higher than that of the group of 37 - 60 months (0%). Three of the children in the group of 0 - 12 months (17.6%) had digestive system symptoms.

CONCLUSION

Transfer of phrenic nerve operated on children younger than 3 years may cause abnormalities of respiratory system, thorax, and digestive system. The younger the patients the more severe the consequences of the operation. The children older than 3 years tolerate the operation better.

Pulmonary function after complete unilateral phrenic nerve transection

Object

The status of pulmonary function following phrenic nerve transfer surgery is still largely unknown because of the high degree of variability in the accessory phrenic nerve that may be involved. In the present study, pulmonary functions were assessed in patients before and after full-length phrenic nerve transfer surgery, in whom the phrenic nerve was severed at a location just before its entry into the diaphragm.

Methods

Fifteen patients (average age 27.4 years) with complete brachial plexus palsy underwent full-length phrenic nerve transfer. The phrenic nerve was harvested from the thoracic cavity by means of video-assisted thoracic surgery and then transferred to the musculocutaneous nerve. Postoperative pulmonary functions were retrospectively analyzed. Patients underwent follow-up evaluation for 42 to 48 months; four patients were eventually lost to follow up.

Although no patient experienced pulmonary problems following the surgery, all sustained varying degrees of diaphragmatic paralysis and elevation (for 1–1.5 intercostal spaces) on the surgically treated side as seen on chest x-ray films. Pulmonary functional parameters, including vital capacity, vital capacity in percentage of predicted values, residual volume, total lung capacity, forced vital capacity, and forced expiratory volume in 1 second, recovered to preoperative levels by 1 year postsurgery. In contrast, the postoperative maximal inspiratory pressure value was significantly decreased compared with the predicted values (average decrease ∼20%) in all of the patients, even at 4 years after the surgery.

Conclusions

In young patients with healthy lung function, unilateral phrenic nerve transection surgery can cause unilateral diaphragmatic paralysis and reduce the inspiration muscle force; however, most pulmonary function parameters gradually recover to preoperative levels within 1 year.

Selective neurotization of the median nerve in the arm to treat brachial plexus palsy. Surgical technique

BACKGROUND

The current method for treatment of median nerve palsy after a brachial plexus injury is unpredictable. On the basis of an anatomic study of the median nerve in the arm, we present a new method of selective neurotization of the median nerve.

METHODS

Internal topographic features of the fascicular groups of the median nerve were observed in seventeen cadavera. On the basis of the anatomical results, selective neurotization of the posterior fascicular group of the median nerve in the arm was performed in one patient with a complete brachial plexus palsy.

RESULTS

In the distal half of the arm, the branches of the median nerve consistently collect into three fascicular groups, which are located at the anterior, middle, and posterior parts of the median nerve trunk. The anterior fascicular group is composed of the branches to the pronator teres and the flexor carpi radialis, the posterior fascicular group is composed mainly of the anterior interosseous nerve and the branches to the palmaris longus, and the middle fascicular group is made up mostly of the branches to the hand and the flexor digitorum superficialis. A transfer of the full length of the phrenic nerve was used to selectively reinnervate the posterior fascicular group of the median nerve in a patient with a complete brachial plexus palsy. The muscles supplied by the posterior fascicular group regained Grade-4 power, according to the system of the Medical Research Council, sixteen months after surgery.

CONCLUSIONS

The typical arrangement of the fascicular groups of the median nerve in the arm favors the technique of selective neurotization, which has been used effectively in one patient to date.

The role of the large superficial vein in survival of proximally based versus distally based sural veno-neuro-fasciocutaneous flaps in a rabbit model

A sural veno-neuro-fasciocutaneous flap in the New Zealand White rabbit was developed, and the role of the large subcutaneous lesser saphenous vein was investigated in proximally based versus distally based flaps. Retrograde dye injection showed that the lesser saphenous vein in rabbits has many valves with strong resistance against reflux. Twenty rabbits were randomly allocated into four groups of 10 flaps each. Group I consisted of proximally based flaps with the lesser saphenous vein intact (outflow) in the veno-neuro-adipofascial pedicle. Group II also consisted of proximally based flaps but the lesser saphenous vein was ligated at 1 cm proximal to the pedicle. Group III consisted of distally based flaps with the lesser saphenous vein intact (inflow) in the veno-neuro-adipofascial pedicle. Group IV also consisted of distally based flaps, but the lesser saphenous vein was ligated at 1 cm distal to the pedicle. The results showed that the mean flap survival area in group I (88.8 percent) was statistically higher than that in group II (62.6 percent, p < 0.001), and was higher in group IV (55.5 percent) than in group III (22.7 percent, p < 0.01). However, group II and group IV had no significant difference (p > 0.05). This experiment demonstrated that flap viability is determined by its intrinsic vascularization, both arterial and venous. The large superficial subcutaneous vein has a positive role (venous outflow) in proximally based flaps but a negative role (venous inflow) in distally based flaps. If the effect of the large subcutaneous vein is excluded, distally based flaps are not inherently inferior to proximally based flaps.

Comparative clinic study on vascularized and nonvascularized full-length phrenic nerve transfer

In order to understand whether the vascularizing procedure has any clinical value in nerve transfer and grafting, we compared nonvascularized and vascularized full-length phrenic never transfers in patients with a brachial plexus injury. Full-length phrenic nerve transfer to the musculocutaneous nerve had been conducted by the technique of video-assisted thoracic surgery in 15 patients. Three kinds of procedures were carried out. The first involved retaining the initial point of the phrenic nerve and dissecting the full-length distal nerve. The second involved keeping the cervical segment and isolating the thoracic segment of the phrenic nerve. The last involved vascularized phrenic nerve transfer. All these phrenic nerves were sutured to musculocutaneous nerves. After 28-35 months, the results of electrophysiology and function of the biceps brachii muscle were compared. All three procedures had no significant differences and led to the same functional recovery of the biceps brachii muscle after at least 28 months of follow-up. In conclusion, the vascularizing procedure had little clinical value, not only in full-length phrenic nerve transfer, but also in nerve grafting irrespective of the length of the gap, when the recipient bed had normal vascularity.

Ultrastructural Analysis of Peripheral-Nerve Regeneration within a Nerve Conduit

The purpose of this study was to observe the cellular components of regenerating peripheral nerves within a nerve conduit. Rat sciatic nerves were placed in a silicone conduit with a 5-mm gap between nerve endings. At weekly intervals for 6 weeks, 70-nm sections of nerve tissue from the conduit were obtained for ultrastructural observation. The principal cellular components by the end of the first week were macrophages and fibroblasts. By the end of the second week, both myelinated and unmyelinated nerve fibers began to pass through the entire conduit. By the end of the fifth week, nerve fibers were present at various levels of maturity, with no evidence of inflammatory or immunologic response. By the end of the sixth week, the percentage of nerve fibers was 86 percent of the cellular components. This analysis provides cellular data on which to base additional research regarding functional outcomes when using nerve conduits.