Outcome following phrenic nerve transfer to musculocutaneous nerve in patients with traumatic brachial palsy: a qualitative systematic review

VATS phrenic nerve harvesting for brachial plexus neurotization: literature review and our experience

INTRODUCTION

Brachial plexus traumatic lesions often lead to severe upper extremity deficits that dramatically compromise quality of life of mostly young patients. Optimal treatment aims to restore elbow flexion transferring various donor nerves. Phrenic nerve (PN) is a powerful source of transferable axons and, despite supraclavicular sectioning being the most used technique, it can be harvested through video-assisted thoracoscopic surgery (VATS).

EVIDENCE ACQUISITION

About PN harvesting, less than 20 articles were found in Literature. Most of them are clinical case-reports or case-series or expert opinions. Most of these studies are from China and East Asia and very rarely from Europe; none from Italy. Therefore, we present our experience in PN VATS harvesting in two patients, first cases reported in Italy.

EVIDENCE SYNTHESIS

Few papers explore risks and benefits of PN as a donor site for brachial plexus reconstruction. There is no clear consensus in the literature whether a traditional approach or minimally invasive surgery is advisable to harvest PN for neurotization. Currently there's no clear indication nor a definitive contraindication about routine use of PN for surgical treatment of BPTLs, it's mostly a matter of choosing the best donor nerve for every single patient. This choice depends on the patient's characteristics, type of traumatic lesion, time from the traumatic event and on the center's experience. The only real concern about using PN as a donor is the potential loss of pulmonary function. In our center two patients with complete brachial plexus avulsion underwent PN transfer via VATS in 2021. Usually, recovery of muscle function depends on time between injury and surgical repair. A commonly accepted recommendation is to perform surgery within six months from the traumatic lesion12. In our experience, the time between trauma and surgery was five months for patient A and six months for patient B. Even if some authors13 consider previous thoracic trauma with rib fractures a major contraindication for homolateral PN harvesting, we believe that the presence of pleural adhesions should not exclude a patient from surgery. No intra or postoperative complications were observed. Both patients were discharged on IV postoperative day. An intense rehabilitation program within three months after surgery is mandatory and regular follow-up is needed to monitor any improvement. No respiratory symptoms or discomfort is recorded up to now.

CONCLUSIONS

Nerve transfer is a safe and reliable surgical reconstructive procedure and phrenic nerve, due to its pure motor nature, is a very good donor for brachial plexus injuries14. VATS is a valid procedure to guarantee a much longer nerve, avoiding any graft use, and doesn't seem to determine significant pulmonary function loss. Previous thoracic trauma, rib fractures and pneumothorax are commonly considered contraindications for VATS harvesting. However, a major trauma leading to BPTL often implies homolateral thoracic trauma with or without rib fracture or pneumothorax. This could be a reasonable justification to reconsider those contraindications and extend the potential cohort of patients that could benefit from this technique.

Phrenic Nerve Transfer to Musculocutaneous Nerve: An Anatomical and Histological Study

BACKGROUND

To restore elbow flexor muscle function in case of traumatic brachial plexus avulsion, the phrenic nerve transfer to the musculocutaneous nerve has become part of clinical practice. The nerve transfer can be done by means of video-assisted thoracic surgery without nerve graft or via supraclavicular approach in combination with an autograft. This study focuses on a detailed microscopic and macroscopic examination of the phrenic nerve. It will allow a better interpretation of existing clinical results and, thus, serve as a basis for future clinical studies.

MATERIAL AND METHODS

An anatomical study was conducted on 28 body donors of Caucasian origin (female n = 14, male n = 14). A sliding caliper and measuring tape were used to measure the diameter and length of the nerves. Sudan black staining was performed on 15 µm thick cryostat sections mounted on glass slides and the number of axons was determined by the ImageJ counting tool. In 23 individuals, the phrenic nerve could be examined on both sides. In 5 individuals, however, only one side was examined. Thus, a total of 51 nerves were examined.

RESULTS

The mean length of the left phrenic nerves (33 cm (29-38 cm)) was significantly longer compared to the mean length of the right phrenic nerves (30 cm (24-33 cm)) (p < 0.001). Accessory phrenic nerves were present in 9 of 51 (18%) phrenic nerves. The mean number of phrenic nerves axons at the level of the first intercostal space in body donors with a right accessory phrenic nerve was significantly greater compared to the mean number of phrenic nerves axons at the same level in body donors without a right accessory phrenic nerve (3145 (range, 2688-3877) vs. 2278 (range, 1558-3276)), p = 0.034. A negative correlation was registered between age and the nerve number of axons in left (0.742, p < 0.001) and right (-0.273, p = 0.197) phrenic nerves. The mean distance from the upper edge of the ventral ramus of the fourth cervical spinal nerve to the point of entrance of the musculocutaneous nerve between the two parts of the coracobrachialis muscle was 19 cm (range, 15-24 cm) for the right and 20 cm (range, 15-25 cm) for the left arm.

CONCLUSIONS

If an accessory phrenic nerve is available, it presumably should be spared. Thus, in that case, a supraclavicular approach in combination with a nerve graft would probably be of advantage.

Video-assisted thoracoscopic surgery (VATS) aided full-length phrenic nerve transfer for restoration of elbow flexion

BACKGROUND

In complete brachial plexus injury, phrenic nerve (PN) is frequently used in neurotization for elbow flexion restoration. The advancement in video-assisted thoracoscopic surgery (VATS) allows full-length PN dissection intrathoracically for direct coaptation to recipient without nerve graft.

PURPOSE

We report our experience in improving the surgical technique and its outcome.

METHODS

Seven patients underwent PN dissection via VATS and full-length transfer to musculocutaneous nerve (MCN) or motor branch of biceps (MBB) from June 2015 to June 2018. Comparisons were made with similar group of patients who underwent conventional PN transfer.

RESULTS

Mean age of patients was 21.9 years. All were males involved in motorcycle accidents who sustained complete brachial plexus injury. We found the elbow flexion recovery were earlier in full-length PN transfer. However, there was no statistically significant difference in elbow flexion strength at 3 years post-surgery.

CONCLUSION

We propose full-length PN transfer for restoration of elbow flexion in patients with delayed presentation.

Restoring musculocutaneous nerve function in 146 brachial plexus operations – a retrospective analysis

INTRODUCTION

A brachial plexus lesion is a devastating injury often affecting young, male adults after traffic accidents. Therefore, surgical restoration of elbow flexion is critical for establishing antigravity movement of the upper extremity. We analyzed different methods for musculocutaneous reconstruction regarding outcome.

METHODS

We conducted a retrospective analysis of 146 brachial plexus surgeries with musculocutaneous reconstruction performed at our department from 2013 to 2017. Demographic data, surgical method, donor and graft nerve characteristics, body mass index (BMI) as well as functional outcome of biceps muscle based on medical research council (MRC) strength grades before and after surgery were analyzed. Multivariate analysis was performed using SPSS.

RESULTS

Oberlin reconstruction was the procedure performed most often (34.2%, n = 50). Nerve transfer and autologous repair showed no significant differences regarding outcome (p = 0.599, OR 0.644 CI95% 0.126-3.307). In case of nerve transfers, we found no significant difference whether reconstruction was performed with or without a nerve graft (e.g. sural nerve) (p = 0.277, OR 0.619 CI95% 0.261-1.469). Multivariate analysis identifies patient age as a strong predictor for outcome, univariate analysis indicates that nerve graft length > 15 cm and BMI of > 25 could lead to inferior outcome. When patients with early recovery (n = 19) are included into final evaluation after 24 months, the general success rate of reconstructions is 62,7% (52/83).

CONCLUSION

Reconstruction of musculocutaneous nerve after brachial plexus injury results in a high rate of clinical improvement. Nerve transfer and autologous reconstruction both show similar results. Young age was confirmed as an independent predictor for better clinical outcome. Prospective multicenter studies are needed to further clarify.

Neurotization of musculocutaneous nerve with intercostal nerve versus phrenic nerve – A retrospective comparative study

Background:

Brachial plexus injuries are common after both blunt and penetrating traumas resulting in upper limb weakness. The nerve transfer to the affected nerve distal to the injury site is a good option where proximal stump of the nerve is unhealthy or absent which has shown early recovery and better results. Commonly used procedures to restore elbow flexion are ipsilateral phrenic or ipsilateral intercostal nerves (ICNs) in global plexus injuries. The use of both intercostal and phrenic nerves for elbow flexion is well described and there is no definite consensus on the superiority of one on another.

Methods:

All patients presented in the outpatient department of LNH and MC from January 2014 to December 2017 with pan plexus or upper plexus injury with no signs of improvement for at least 3 months were included in the study. After 3 months of conservative trial; surgery offered to patients.

Results:

A total of 25 patients (n = 25) were operated from January 2015 to December 2017. Patients were followed to record Medical Research Council (MRC) grades at 3, 6, 9, 12, and 18 months. The patients achieved at least MRC Grade 3; 70% at 12 months follow-up to 80% at 18 months in the phrenic nerve transfer group. While in the ICN transfer group, it is 86% and 100% at 12 and 18 months postoperative, respectively.

Conclusion:

Our study has shown better results with ICN transfers to musculocutaneous nerve, recorded on MRC grading system.

Validity of range of motion, muscle strength, sensitivity, and Tinel sign tele-assessment in adults with traumatic brachial plexus injury

Background

The COVID-19 pandemic and the need for social distancing created challenges for accessing and providing health services. Telemedicine enables prompt evaluation of patients with traumatic brachial plexus injury, even at a distance, without prejudice to the prognosis. The present study aimed to verify the validity of range of motion, muscle strength, sensitivity, and Tinel sign tele-assessment in adults with traumatic brachial plexus injury (TBPI).

Methods

A cross-sectional study of twenty-one men and women with TBPI admitted for treatment at a Rehabilitation Hospital Network was conducted. The participants were assessed for range of motion, muscle strength, sensitivity, and Tinel sign at two moments: in-person assessment (IPA) and tele-assessment (TA).

Results

The TA muscle strength tests presented significant and excellent correlations with the IPA (the intra-rater intraclass correlation coefficient, ICC ranged between 0.79 and 1.00 depending on the muscle tested). The agreement between the TA and IPA range of motion tests ranged from substantial to moderate (weighted kappa coefficient of 0.47–0.76 (p < 0.05) depending on the joint), and the kappa coefficient did not indicate a statistically significant agreement in the range of motion tests of supination, wrist flexors, shoulder flexors, and shoulder external rotators. The agreement between the IPA andTA sensitivity tests of all innervations ranged from substantial to almost perfect (weighted kappa coefficient 0.61–0.83, p < 0.05) except for the C5 innervation, where the kappa coefficient did not indicate a statistically significant agreement. The IPA versus TA Tinel sign test showed a moderate agreement (weighted kappa coefficient of 0.57, p < 0.05).

Conclusions

The present study demonstrated that muscle strength tele-assessment is valid in adults with TBPI and presented a strong agreement for many components of TA range of motion, sensitivity, and Tinel sign tests.

The Terminal Anatomy of Phrenic Nerve: a Deeper Look at Diaphragm Innervation Patterns

BACKGROUND

Traumatic brachial plexus injuries are devastating lesions and neurotization is an usually elected surgical therapy. The phrenic nerve has been harvested as motor fibers donor in brachial plexus neurotization, showing great results in terms of motor reinnervation. Unfortunately, these interventions lack solid evidence regarding long-term safety and possible late respiratory function sequelae, raising crescent concerns after the COVID-19 pandemic onset and possibly resulting in reduced propensity to use this technique. The study of the distal anatomy of the phrenic nerves may lead to a better understanding of their branching patterns, and thus the proposition of surgical approaches that better preserve patient respiratory function.

METHODS

Twenty-one phrenic nerves in ten formalized cadavers were scrutinized. Pre-diaphragmatic branching patterns were inspected through analysis of the distance between the piercing site of the nerve at the diaphragm and the cardiac structures, number of divisions, and length from the point where the main trunk emits its branches to the diaphragm.

RESULTS

The main trunk of the right phrenic nerve reaches the diaphragm near the inferior vena cava and branches into three major divisions. The left phrenic nerve reaches the diaphragm in variable locations near the heart, branching into two to five main trunks. Moreover, we noticed a specimen presenting two ipsilateral parallel phrenic nerves.

CONCLUSION

The right phrenic nerve presented greater consistency concerning insertion site, terminal branching point distance to this muscle, and number of rami than the left phrenic nerve.

Treatment Trends of Adult Brachial Plexus Injury: A Bibliometric Analysis

Brachial plexus injury is often debilitating because it can severely impair upper extremity function and, thus, quality of life. The surgical treatment of injuries to the brachial plexus is very demanding because it requires a profound understanding of the anatomy and expertise in microsurgery. The aim of this study was to get an overview of the landscape in adult brachial plexus injury surgery, and to understand how this has changed over the years.

Methods

The most frequently cited articles in English relevant to adult brachial plexus injury were identified through the Web of Science online database.

Results

The average number of citations per article was 32.8 (median 24, range 4-158). Authors from 26 countries contributed to our list, and the US was the biggest contributor. Almost half of all nerve transfer cases were described by Asian authors. Amongst nerve transfer, the spinal accessory nerve was the preferred donor overall, except in Asia, where intercostal nerves were preferred. Distal nerve transfers were described more often than plexo-plexal and extra-plexal-to-plexal transfers. The most common grafts were sural nerve grafts and vascularized ulnar nerve grafts, which became popular in the last decade.

Conclusions

Our study sheds light on the regional variations in treatment trends of adult brachial plexus injury, and on the evolution of the field over the last 30 years. The articles included in our analysis are an excellent foundation for those interested in the surgical management of brachial plexus injuries.

Nerve Graft Length and Recovery of Elbow Flexion Muscle Strength in Patients With Traumatic Brachial Plexus Injuries: Case Series

BACKGROUND

Traumatic brachial plexus injuries cause long-term maiming of patients. The major target function to restore in complex brachial plexus injury is elbow flexion.

OBJECTIVE

To retrospectively analyze the correlation between the length of the nerve graft and the strength of target muscle recovery in extraplexual and intraplexual nerve transfers.

METHODS

A total of 51 patients with complete or near-complete brachial plexus injuries were treated with a combination of nerve reconstruction strategies. The phrenic nerve (PN) was used as axon donor in 40 patients and the spinal accessory nerve was used in 11 patients. The recipient nerves were the anterior division of the upper trunk (AD), the musculocutaneous nerve (MC), or the biceps branches of the MC (BBs). An index comparing the strength of elbow flexion between the affected and the healthy arms was correlated with the choice of target nerve recipient and the length of nerve grafts, among other parameters. The mean follow-up was 4 yr.

RESULTS

Neither the choice of MC or BB as a recipient nor the length of the nerve graft showed a strong correlation with the strength of elbow flexion. The choice of very proximal recipient nerve (AD) led to axonal misrouting in 25% of the patients in whom no graft was employed.

CONCLUSION

The length of the nerve graft is not a negative factor for obtaining good muscle recovery for elbow flexion when using PN or spinal accessory nerve as axon donors in traumatic brachial plexus injuries.

Long-Term Outcome of Phrenic Nerve Transfer in Brachial Plexus Avulsion Injuries

INTRODUCTION

In brachial plexus injuries, useful recovery of arm function has been documented in most patients after phrenic nerve transfer after variable follow-up durations, but there is not much information about long-term functional outcomes. In addition, there is still some concern that respiratory complications might become manifest with aging. The aim of this study was to report the outcome of phrenic nerve transfer after a minimum follow-up of 5 years.

PATIENTS AND METHODS

Twenty-six patients were reviewed and evaluated clinically. Age at surgery averaged 25.2 years and follow-up averaged 9.15 years.

RESULTS

Shoulder abduction and external rotation achieved by transfer of phrenic to axillary nerve (or posterior division of upper trunk), combined with spinal accessory to suprascapular nerve transfer, were better than that achieved by transfer of phrenic to suprascapular nerve, combined with grafting the posterior division of upper trunk from C5, 52.3 and 45.5 degrees versus 47.5 and 39.4 degrees, respectively. There was no difference in abduction when the phrenic nerve was transferred directly to the posterior division of upper trunk or to the axillary nerve using nerve graft. Elbow flexion (≥M3 MRC) was achieved in 5 (83.3%) of 6 cases. Elbow extension M4 MRC or greater was achieved in 4 (66.6%) of 6 cases. All patients, including those who exceeded the age of 45 years and those who had concomitant intercostal nerve transfer, continued to have no respiratory symptoms.

CONCLUSIONS

The long-term follow-up confirms the safety and effectiveness and of phrenic nerve transfer for functional restoration of shoulder and elbow functions in brachial plexus avulsion injuries.

Anatomical feasibility of peripheral nerve transfer to reestablish external anal sphincter control - cadaveric study

PURPOSE

Motor deficits affecting anal sphincter control can severely impair quality of life. Peripheral nerve transfer has been proposed as an option to reestablish anal sphincter motor function. We assessed, in human cadavers, the anatomical feasibility of nerve transfer from a motor branch of the tibialis portion of the sciatic nerve to two distinct points on pudendal nerve (PN), through transgluteal access, as a potential approach to reestablish anal sphincter function.

METHODS

We dissected 24 formalinized specimens of the gluteal region and posterior proximal third of the thigh. We characterized the motor fascicle (donor nerve) from the sciatic nerve to the long head of the biceps femoris muscle and the PN (recipient nerve), and measured nerve lengths required for direct coaptation from the donor nerve to the recipient in both the gluteal region (proximal) and perineal cavity (distal).

RESULTS

We identified three anatomical variations of the donor nerve as well as three distinct branching patterns of the recipient nerve from the piriformis muscle to the pudendal canal region. Donor nerve lengths (proximal and distal) were satisfactory for direct coaptation in all cases.

CONCLUSIONS

Transfer of a motor fascicle of the sciatic nerve to the PN is anatomically feasible without nerve grafts. Donor nerve length was sufficient and donor nerve functionally compatible (motor). Anatomical variations in the PN could also be accommodated.

Comparison Between Supraclavicular Versus Video-Assisted Intrathoracic Phrenic Nerve Section for Transfer in Patients With Traumatic Brachial Plexus Injuries: Case Series

BACKGROUND

The phrenic nerve has been extensively reported to be a very powerful source of transferable axons in brachial plexus injuries. The most used technique used is supraclavicular sectioning of this nerve. More recently, video-assisted thoracoscopic techniques have been reported as a good alternative, since harvesting a longer phrenic nerve avoids the need of an interposed graft.

OBJECTIVE

To compare grafting vs phrenic nerve transfer via thoracoscopy with respect to mean elbow strength at final follow-up.

METHODS

A retrospective analysis was conducted among patients who underwent phrenic nerve transfer for elbow flexion at 2 centers from 2008 to 2017. All data analysis was performed in order to determine statistical significance among the analyzed variables.

RESULTS

A total of 32 patients underwent supraclavicular phrenic nerve transfer, while 28 underwent phrenic nerve transfer via video-assisted thoracoscopy. Demographic characteristics were similar in both groups. A statistically significant difference in elbow flexion strength recovery was observed, favoring the supraclavicular phrenic nerve section group against the intrathoracic group (P = .036). A moderate though nonsignificant difference was observed favoring the same group in mean elbow flexion strength. Also, statistical differences included patient age (P = .01) and earlier time from trauma to surgery (P = .069).

CONCLUSION

Comparing supraclavicular sectioning of the nerve vs video-assisted, intrathoracic nerve sectioning to restore elbow flexion showed that the former yielded statistically better results than the latter, in terms of the percentage of patients who achieve at least level 3 MRC strength at final follow-up. Furthermore, larger scale prospective studies assessing the long-term effects of phrenic nerve transfers remain necessary.

Intercostal to musculocutaneous nerve transfer in patients with complete traumatic brachial plexus injuries: case series

BACKGROUND

To recover biceps strength in patients with complete brachial plexus injuries, the intercostal nerve can be transferred to the musculocutaneous nerve. The surgical results are very controversial, and most of the studies with good outcomes and large samples were carried out in Asiatic countries. The objective of the study was to evaluate biceps strength after intercostal nerve transfer in patients undergoing this procedure in a Western country hospital.

METHODS

We retrospectively analyzed 39 patients from 2011 to 2016 with traumatic brachial plexus injuries receiving intercostal to musculocutaneous nerve transfer in a rehabilitation hospital. The biceps strength was graded using the British Medical Research Council (BMRC) scale. The variables reported and analyzed were age, the time between trauma and surgery, surgeon experience, body mass index, nerve receptor (biceps motor branch or musculocutaneous nerve), and the number of intercostal nerves transferred. Statistical tests, with a significance level of 5%, were used.

RESULTS

Biceps strength recovery was graded ≥M3 in 19 patients (48.8%) and M4 in 15 patients (38.5%). There was no statistical association between biceps strength and the variables. The most frequent complication was a pleural rupture.

CONCLUSIONS

Intercostal to musculocutaneous nerve transfer is a safe procedure. Still, biceps strength after surgery was ≥M3 in only 48.8% of the patients. Other donor nerve options should be considered, e.g., the phrenic or spinal accessory nerves.

Intercostal nerve transfer for restoration of the diaphragm muscle function after phrenic nerve transfer in total brachial plexus avulsion

OBJECT

To determine the possibility of innervation of the diaphragm muscle using intercostal nerve after ipsilateral phrenic nerve transfer in total brachial plexus avulsion.

METHODS

Bilateral phrenic nerves and the 9th intercostal nerves were observed inside the thorax. The point where the phrenic nerve entered the diaphragm muscle (point A), the point where the 9th intercostal nerve gave rise to the cutaneous branch (point B) and crossed the posterior axillary line (point C) and the point where the posterior axillary line met the insertion of the diaphragm muscle (point D) were identified. The distances between points B and C, points A and C and from points A through D to C were recorded respectively. The 9th intercostal nerve was transferred to the distal stump of the phrenic nerve in one patient after phrenic nerve transfer to avulsed brachial plexus.

RESULTS

The mean distances between points B and C, points A and C and from points A through D to C were 12.20 ± 1.04 cm, 10.32 ± 1.02 cm and 16.43 ± 0.91 cm on the right side respectively, 11.78 ± 1.21 cm, 7.77 ± 0.85 cm and 11.74 ± 1.00 cm on the left side respectively. The 9th intercostal nerve was used to innervate the distal stump of the phrenic nerve in one patient after the phrenic nerve transfer to the avulsed brachial plexus. The diaphragm muscle function partially recovered one year after the operation.

CONCLUSION

The 9th intercostal nerve can be transferred to the distal stump of the phrenic nerve to restore the diaphragm muscle function according to the anatomical study. The movement of the diaphragm muscle was partially restored in one clinical case.

Traumatic brachial plexus injury: a study of 510 surgical cases from multicenter services in Guangxi, China

BACKGROUND

Traumatic brachial plexus injuries are severe lesions, and the incidence of these injuries has been increasing in recent years.

METHODS

The clinical data of 510 operated patients with brachial plexus injury recruited from 74 hospitals in Guangxi from 2004 to 2016 were retrospectively studied.

RESULTS

Our study included 447 males and 63 females, with an average age of 29.04 years. Traffic accidents were the most common cause of injury (64.71%), especially motorcycle accidents. Closed injuries accounted for 88.24% of cases, and 83.53% of patients had associated injuries, the most common of which were fractures (76.27%). The preoperative predictive value of root injury of MRI and CT was 74.71% and 71.28%, respectively. 44.71% of patients underwent an initial operation within 6 months after the trauma. Regarding the surgery, neurolysis alone, brachial plexus reconstruction, and free functioning gracilis graft accounted for 16.67%, 75.50%, and 4.51%, respectively. A total of 415 patients were followed up with an average time of 47.95 (25-68) months, and anxiety or depression were found among 81.20% of them. Two hundred seventy-six patients suffered from nerve pain, with mild pain present in 67.03% of patients. Additionally, 347 patients were followed up for more than 3 years, 76.81% of patients with C5-C6 injury recovery to useful function, and the procedure of neurolysis alone demonstrated the best efficacy (79.45%).

CONCLUSIONS

Brachial plexus injury is still a challenging trauma for surgeons, and traffic accidents are the dominant cause. Timely and effective surgery is important for functional limb recovery.

Results of Phrenic Nerve Transfer to the Musculocutaneous Nerve Using Video-Assisted Thoracoscopy in Patients with Traumatic Brachial Plexus Injury: Series of 28 Cases

BACKGROUND

The phrenic nerve can be transferred to the musculocutaneous nerve using video-assisted thoracoscopy, aiming at the recovery of elbow flexion in patients with traumatic brachial plexus injuries. There are few scientific papers in the literature that evaluate the results of this operative technique.

OBJECTIVE

To evaluate biceps strength and pulmonary function after the transfer of the phrenic nerve to the musculocutaneous nerve using video-assisted thoracoscopy.

METHODS

A retrospective study was carried out in a sample composed of 28 patients who were victims of traumatic injury to the brachial plexus from 2008 to 2013. Muscle strength was graded using the British Medical Research Council (BMRC) scale and pulmonary function through spirometry. Statistical tests, with significance level of 5%, were used.

RESULTS

In total, 74.1% of the patients had biceps strength greater than or equal to M3. All patients had a decrease in forced vital capacity and forced expiratory volume in 1 s, with no evidence of recovery over time.

CONCLUSION

Transferring the phrenic nerve to the musculocutaneous nerve using video-assisted thoracoscopy may lead to an increase in biceps strength to BMRC M3 or greater in most patients. Considering the deterioration in the parameters of spirometry observed in our patients and the future effects of aging in the respiratory system, it is not possible at the moment to guarantee the safety of this operative technique in the long term.

Comparative study of phrenic and partial ulnar nerve transfers for elbow flexion after upper brachial plexus avulsion: A retrospective clinical analysis

The widely used nerve transfer sources for elbow flexion in patients with upper brachial plexus avulsion (UBPA) include partial ulnar nerve, phrenic nerve, and intercostal nerves. A retrospective review of 21 patients treated with phrenic and partial ulnar nerve transfers for elbow flexion after UBPA was carried out. In the phrenic nerve transfer group, the phrenic nerve was transferred to the anterolateral bundle of the anterior division of the upper trunk; in the partial ulnar nerve transfer group, one fascicle of the ulnar nerve was transferred to the biceps branch. The British Medical Research Council (MRC) grading system, angle of elbow flexion, electromyography (EMG), and the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire scoring were used to evaluate the recovery of elbow flexion at least 3 years postoperatively. The efficiency of motor function in phrenic nerve transfer group was 82%, whereas it was 80% in partial ulnar nerve transfer group. The outstanding rates of angle of elbow flexion were 64% and 70% in phrenic and partial ulnar nerve transfer groups, respectively. The DASH scores after surgery were significantly lower than those before surgery in the two groups. There was no statistical difference between the two groups in the changes of DASH scores before and after surgery. Both of phrenic and partial ulnar nerve transfers had good prognosis for elbow flexion in patients with UBPA.

Tomographic optical imaging of cortical responses after crossing nerve transfer in mice

To understand the neural mechanisms underlying the therapeutic effects of crossing nerve transfer for brachial plexus injuries in human patients, we investigated the cortical responses after crossing nerve transfer in mice using conventional and tomographic optical imaging. The distal cut ends of the left median and ulnar nerves were connected to the central cut ends of the right median and ulnar nerves with a sciatic nerve graft at 8 weeks of age. Eight weeks after the operation, the responses in the primary somatosensory cortex (S1) elicited by vibratory stimulation applied to the left forepaw were visualized based on activity-dependent flavoprotein fluorescence changes. In untreated mice, the cortical responses to left forepaw stimulation were mainly observed in the right S1. In mice with nerve crossing transfer, cortical responses to left forepaw stimulation were observed in the left S1 together with clear cortical responses in the right S1. We expected that the right S1 responses in the untreated mice were produced by thalamic inputs to layer IV, whereas those in the operated mice were mediated by callosal inputs from the left S1 to layer II/III of the right S1. To confirm this hypothesis, we performed tomographic imaging of flavoprotein fluorescence responses by macroconfocal microscopy. Flavoprotein fluorescence responses in layer IV were dominant compared to those in layer II/III in untreated mice. In contrast, responses in layer II/III were dominant compared to those in layer IV in operated mice. The peak latency of the cortical responses in the operated mice was longer than that in the untreated mice. These results confirmed our expectation that drastic reorganization in the cortical circuits was induced after crossing nerve transfer in mice.

Rehabilitation, Using Guided Cerebral Plasticity, of a Brachial Plexus Injury Treated with Intercostal and Phrenic Nerve Transfers

Recovery after surgical reconstruction of a brachial plexus injury using nerve grafting and nerve transfer procedures is a function of peripheral nerve regeneration and cerebral reorganization. A 15-year-old boy, with traumatic avulsion of nerve roots C5–C7 and a non-rupture of C8–T1, was operated 3 weeks after the injury with nerve transfers: (a) terminal part of the accessory nerve to the suprascapular nerve, (b) the second and third intercostal nerves to the axillary nerve, and (c) the fourth to sixth intercostal nerves to the musculocutaneous nerve. A second operation—free contralateral gracilis muscle transfer directly innervated by the phrenic nerve—was done after 2 years due to insufficient recovery of the biceps muscle function. One year later, electromyography showed activation of the biceps muscle essentially with coughing through the intercostal nerves, and of the transferred gracilis muscle by deep breathing through the phrenic nerve. Voluntary flexion of the elbow elicited clear activity in the biceps/gracilis muscles with decreasing activity in intercostal muscles distal to the transferred intercostal nerves (i.e., corresponding to eighth intercostal), indicating cerebral plasticity, where neural control of elbow flexion is gradually separated from control of breathing. To restore voluntary elbow function after nerve transfers, the rehabilitation of patients operated with intercostal nerve transfers should concentrate on transferring coughing function, while patients with phrenic nerve transfers should focus on transferring deep breathing function.