Clinicopathological study of malignant peripheral nerve sheath tumors in the head and neck:Case reports and review of literature

BACKGROUND Malignant peripheral nerve sheath tumor(MPNST)is a rare and aggressive soft tissue sarcoma that poses a major diagnostic and therapeutic challenge.CASE SUMMARY We retrospectively reviewed patients with head and neck MPNSTs treated in our hospital from 2000 to 2021.The clinical features,pathological manifestations,treatments,and prognoses were summarized.We also reviewed the literature,focusing on MPNST in the mandible and maxilla.The study population consisted of five women and five men aged 22–75 years(mean age,49 years).Of the 10 patients,7 were initial cases and 3 were recurrent cases.All lesions were sporadic.The most common site was the mandible.The most frequently encountered symptoms were a progressive mass and local swelling.Complete or partial loss of trimethylation at lysine 27 of histone H3(H3K27me3)was evident on staining in four of nine cases(one case was excluded due to lack of tissue for evaluation of loss of H3K27me3).The 2-and 5-year disease-specific survival rates were 86%a nd 43%,respectively.The average survival time was 64 mo.CONCLUSION MPNST is a highly malignant tumor with a poor prognosis,prone to a high risk of recurrence and distant metastasis.Complete surgical resection is the main treatment.

Ultrasound-Guided Dorsal Scapular Nerve Blockade in the Diagnosis and Management of Neck Pain

Neck pain is common and has multiple sources, but correct diagnosis and matched treatment provide the best outcomes. The first description of ultrasound-guided dorsal scapular nerve blockade using a single-shot local anesthetic technique for the diagnosis and treatment of neck pain is reported. A 38-year-old female patient presented with neck pain, and the history and clinical examination strongly suggested myofascial pain affecting the middle scalene muscle. The pain had been unresponsive to pharmacological therapy or physiotherapy. After identifying the dorsal scapular nerve (DSN) in the body of the middle scalene muscle, an ultrasound-guided nerve block was performed using a single injection of local anesthetic to alleviate the patient’s pain. It has been demonstrated that the dorsal scapular nerve can be identified in the neck and effectively blocked using ultrasound guidance. This technique has the potential to assist in the diagnosis and treatment of neck pain originating from the middle scalene muscle.

Resting-state brain network remodeling after different nerve reconstruction surgeries:a functional magnetic resonance imaging study in brachial plexus injury rats

Distinct brain remodeling has been found after different nerve reconstruction strategies,including motor representation of the affected limb.However,differences among reconstruction strategies at the brain network level have not been elucidated.This study aimed to explore intranetwork changes related to altered peripheral neural pathways after different nerve reconstruction surgeries,including nerve repair,endto-end nerve transfer,and end-to-side nerve transfer.Sprague–Dawley rats underwent complete left brachial plexus transection and were divided into four equal groups of eight:no nerve repair,grafted nerve repair,phrenic nerve end-to-end transfer,and end-to-side transfer with a graft sutured to the anterior upper trunk.Resting-state brain functional magnetic resonance imaging was obtained 7 months after surgery.The independent component analysis algorithm was utilized to identify group-level network components of interest and extract resting-state functional connectivity values of each voxel within the component.Alterations in intra-network resting-state functional connectivity were compared among the groups.Target muscle reinnervation was assessed by behavioral observation(elbow flexion)and electromyography.The results showed that alterations in the sensorimotor and interoception networks were mostly related to changes in the peripheral neural pathway.Nerve repair was related to enhanced connectivity within the sensorimotor network,while end-to-side nerve transfer might be more beneficial for restoring control over the affected limb by the original motor representation.The thalamic-cortical pathway was enhanced within the interoception network after nerve repair and end-to-end nerve transfer.Brain areas related to cognition and emotion were enhanced after end-to-side nerve transfer.Our study revealed important brain networks related to different nerve reconstructions.These networks may be potential targets for enhancing motor recovery.

Motor neuron-specific RhoA knockout delays degeneration and promotes regeneration of dendrites in spinal ventral horn after brachial plexus injury

Dendrites play irreplaceable roles in the nerve conduction pathway and are vulnerable to various insults.Peripheral axotomy of motor neurons results in the retraction of dendritic arbors,and the dendritic arbor can be re-expanded when reinnervation is allowed.RhoA is a target that regulates the cytoskeleton and promotes neuronal survival and axon regeneration.However,the role of RhoA in dendrite degeneration and regeneration is unknown.In this study,we explored the potential role of RhoA in dendrites.A line of motor neuronal conditional knockout mice was developed by crossbreeding HB9~(Cre+)mice with RhoA~(flox/flox)mice.We established two models for assaying dendrite degeneration and regeneration,in which the brachial plexus was transection or crush injured,respectively.We found that at 28 days after brachial plexus transection,the density,complexity,and structural integrity of dendrites in the ventral horn of the spinal cord of RhoA conditional knockout mice were slightly decreased compared with that in Cre mice.Dendrites underwent degeneration at 7 and 14 days after brachial plexus transection and recovered at 28–56 days.The density,complexity,and structural integrity of dendrites in the ventral horn of the spinal cord of RhoA conditional knockout mice recovered compared with results in Cre mice.These findings suggest that RhoA knockout in motor neurons attenuates dendrite degeneration and promotes dendrite regeneration after peripheral nerve injury.

Human amniotic epithelial cell transplantation for the repair of injured brachial plexus nerve: evaluation of nerve viscoelastic properties

The transplantation of embryonic stem cells can effectively improve the creeping strength of nerves near an injury site in animals. Amniotic epithelial cells have similar biological properties as em-bryonic stem cells; therefore, we hypothesized that transplantation of amniotic epithelial cells can repair peripheral nerve injury and recover the creeping strength of the brachial plexus nerve. In the present study, a brachial plexus injury model was established in rabbits using the C6root avulsion method. A suspension of human amniotic epithelial cells was repeatedly injected over an area 4.0 mm lateral to the cephal and caudal ends of the C6 brachial plexus injury site （1 × 106 cells/mL, 3μL/injection, 25 injections） immediately after the injury. The results showed that the decrease in stress and increase in strain at 7,200 seconds in the injured rabbit C6 brachial plexus nerve were mitigated by the cell transplantation, restoring the viscoelastic stress relaxation and creep properties of the brachial plexus nerve. The forepaw functions were also signiifcantly improved at 26 weeks after injury. These data indicate that transplantation of human amniotic epithelial cells can effec-tively restore the mechanical properties of the brachial plexus nerve after injury in rabbits and that viscoelasticity may be an important index for the evaluation of brachial plexus injury in animals.

Transplantation of human amniotic epithelial cells repairs brachial plexus injury:pathological and biomechanical analyses

A brachial plexus injury model was established in rabbits by stretching the C6 nerve root. Imme- diately after the stretching, a suspension of human amniotic epithelial cells was injected into the injured brachial plexus. The results of tensile mechanical testing of the brachial plexus showed that the tensile elastic limit strain, elastic limit stress, maximum stress, and maximum strain of the injured brachial plexuses were significantly increased at 24 weeks after the injection. The treatment clearly improved the pathological morphology of the injured brachial plexus nerve, as seen by hematoxylin eosin staining, and the functions of the rabbit forepaw were restored. These data indicate that the injection of human amniotic epithelial cells contributed to the repair of brachial plexus injury, and that this technique may transform into current clinical treatment strategies.

Phrenic nerve transfer to the musculocutaneous nerve for the repair of brachial plexus injury: electrophysiological characteristics

Phrenic nerve transfer is a major dynamic treatment used to repair brachial plexus root avulsion. We analyzed 72 relevant articles on phrenic nerve transfer to repair injured brachial plexus that were indexed by Science Citation Index. The keywords searched were brachial plexus injury, phrenic nerve, repair, surgery, protection, nerve transfer, and nerve graft. In addition, we per-formed neurophysiological analysis of the preoperative condition and prognosis of 10 patients undergoing ipsilateral phrenic nerve transfer to the musculocutaneous nerve in our hospital from 2008 to 201 3 and observed the electromyograms of the biceps brachii and motor conduc-tion function of the musculocutaneous nerve. Clinically, approximately 28% of patients had brachial plexus injury combined with phrenic nerve injury, and injured phrenic nerve cannot be used as a nerve graft. After phrenic nerve transfer to the musculocutaneous nerve, the regener-ated potentials ifrst appeared at 3 months. Recovery of motor unit action potential occurred 6 months later and became more apparent at 12 months. The percent of patients recovering ‘ex-cellent’ and ‘good’ muscle strength in the biceps brachii was 80% after 18 months. At 12 months after surgery, motor nerve conduction potential appeared in the musculocutaneous nerve in seven cases. These data suggest that preoperative evaluation of phrenic nerve function may help identify the most appropriate nerve graft in patients with an injured brachial plexus. The func-tional recovery of a transplanted nerve can be dynamically observed after the surgery.

Restoration and protection of brachial plexus injury: hot topics in the last decade

Brachial plexus injury is frequently induced by injuries, accidents or birth trauma. Upper limb function may be partially or totally lost after injury, or left permanently disabled. With the de- velopment of various medical technologies, different types of interventions are used, but their effectiveness is wide ranging. Many repair methods have phasic characteristics, i.e., repairs are done in different phases. This study explored research progress and hot topic methods for pro- tection after brachial plexus injury, by analyzing 1,797 articles concerning the repair of brachial plexus injuries, published between 2004 and 2013 and indexed by the Science Citation Index database. Results revealed that there are many methods used to repair brachial plexus injury, and their effects are varied. Intervention methods include nerve transfer surgery, electrical stimula- tion, cell transplantation, neurotrophic factor therapy and drug treatment. Therapeutic methods in this field change according to the hot topic of research.

Stability of motor endplates is greater in the biceps than in the interossei in a rat model of obstetric brachial plexus palsy

The time window for repair of the lower trunk is shorter than that of the upper trunk in patients with obstetric brachial plexus palsy. The denervated intrinsic muscles of the hand become irreversibly atrophic much faster than the denervated biceps. However, it is unclear whether the motor endplates of the denervated interosseous muscles degenerate more rapidly than those of the denervated biceps. In this study, we used a rat model of obstetric brachial plexus palsy of the right upper limb. C5–6 was lacerated distal to the intervertebral foramina, with concurrent avulsion of C7–8 and T1, with the left upper limb used as the control. Bilateral interossei and biceps were collected at 5 and 7 weeks. Immunofluorescence was used to assess the morphology of the motor endplates. Real-time quantitative polymerase chain reaction and western blot assay were used to assess mRNA and protein expression levels of acetylcholine receptor subunits(α, β and δ), rapsyn and β-catenin. Immunofluorescence microscopy showed that motor endplates in the denervated interossei were fragmented, while those in the denervated biceps were morphologically intact with little fragmentation. The number and area of motor endplates, relative to the control side, were significantly lower in the denervated interossei compared with the denervated biceps. mRNA and protein expression levels of acetylcholine receptor subunits(α, β and δ) were significantly lower, whereas β-catenin protein expression was higher, in the denervated interossei compared with the denervated biceps. The protein expression of rapsyn was higher in the denervated biceps than in the denervated interossei at 7 weeks. Our findings demonstrate that motor endplates of interossei are destabilized, whereas those of the biceps remain stable, in the rat model of obstetric brachial plexus palsy. All procedures were approved by the Experimental Animal Ethics Committee of Fudan University, China(approval No. DF-187) in January 2016.

Use of intercostal nerves for different target neurotization in brachial plexus reconstruction

Intercostal nerve transfer is a valuable procedure in devastating plexopathies. Intercostal nerves are a very good choice for elbow flexion or extension and shoulder abduction when the intraplexus donor nerves are not available. The best results are obtained in obstetric brachial plexus palsy patients, when direct nerve transfer is performed within six months from the injury. Unlike the adult posttraumatic patients after median and ulnar nerve neurotization with intercostal nerves, almost all obstetric brachial plexus palsy patients achieve protective sensation in the hand and some of them achieve active wrist and finger flexion. Use in combination with proper muscles, intercostal nerve transfer can yield adequate power to the paretic upper limb. Reinnervation of native muscles(i.e., latissimus dorsi) should always be sought as they can successfully be transferred later on for further functional restoration.

The expressions of brain-derived neurotrophic factor and nerve growth factor in purified rat choroid plexus epithelial cells in vitro

Objective： To detect the expressions of brain-derived neurotrophic factor （BDNF） and nerve growth factor （NGF） in purified rat choroid plexus epithelial cells in vitro. Methods： Primary and passage choroid plexus epithelial cells were obtained from newborn, one-day Spragne-Dawley rats. The expressions of BDNF and NGF were measured by qRT-PCR and Western blottingting. The secretions of BDNF and NGF were detected by ELISA. Cell supematants of primary cells, purified cells and passage 1 cells were harvested. Results： The expression of BDNF in the purified cells was significantly lower than that in the primary cells （P〈0.05）, and it in the primary cells and the purified cells was significantly higher than that in the passage 1 cells （P〈0.05）. The expression of NGF was significantly higher in the purified cells than in the primary cells and the passage 1 cells （P〈0.05）. It in the passage 1 cells was significantly higher than that in the primary cells （P〈0.05）. Conclusion： The time of CPECs transplantation for central nervous system diseases should be selected based on their secretory function and features,which could lead to better and more effective treatment.

Neural differentiation of choroid plexus epithelial cells:role of human traumatic cerebrospinal fluid

As the key producer of cerebrospinal fluid（CSF）,the choroid plexus（CP） provides a unique protective system in the central nervous system.CSF components are not invariable and they can change based on the pathological conditions of the central nervous system.The purpose of the present study was to assess the effects of non-traumatic and traumatic CSF on the differentiation of multipotent stem-like cells of CP into the neural and/or glial cells.CP epithelial cells were isolated from adult male rats and treated with human non-traumatic and traumatic CSF.Alterations in m RNA expression of Nestin and microtubule-associated protein（MAP2）,as the specific markers of neurogenesis,and astrocyte marker glial fibrillary acidic protein（GFAP） in cultured CP epithelial cells were evaluated using quantitative real-time PCR.The data revealed that treatment with CSF（non-traumatic and traumatic） led to increase in m RNA expression levels of MAP2 and GFAP.Moreover,the expression of Nestin decreased in CP epithelial cells treated with non-traumatic CSF,while treatment with traumatic CSF significantly increased its m RNA level compared to the cells cultured only in DMEM/F12 as control.It seems that CP epithelial cells contain multipotent stem-like cells which are inducible under pathological conditions including exposure to traumatic CSF because of its compositions.

Improved C_(3-4) transfer for treatment of root avulsion of the brachial plexus upper trunk Animal experiments and clinical application

Experimental rats with root avulsion of the brachial plexus upper trunk were treated with the improved C34 transfer for neurotization of 05-6. Results showed that Terzis grooming test scores were significantly increased at 6 months after treatment, the latency of C5-6 motor evoked potential was gradually shortened, and the amplitude was gradually increased. The rate of C3 instead of C5 and the C4 ＋ phrenic nerve instead of C6 myelinated nerve fibers crossing through the anastomotic stoma was approximately 80%. Myelinated nerve fibers were arranged loosely but the thickness of the myelin sheath was similar to that of the healthy side. In clinical applications, 39 patients with root avulsion of the brachial plexus upper trunk were followed for 6 months to 4.5 years after treatment using the improved C3 instead of C5 nerve root transfer and C4 nerve root and phrenic nerve instead of C6 nerve root transfer. Results showed that the strength of the brachial biceps and deltoid muscles recovered to level IIHV, scapular muscle to level Ill-W, latissimus dorsi and pectoralis major muscles to above level Ⅲ, and the brachial triceps muscle to level 0 Ill. Results showed that the improved 03-4 transfer for root avulsion of the brachial plexus upper trunk in animal models is similar to clinical findings and that C3-4 and the phrenic nerve transfer for neurotization of C5-6 can innervate the avulsed brachial plexus upper trunk and promote the recovery of nerve function in the upper extremity.

Structure of the brachial plexus root and adjacent regions displayed by ultrasound imaging

Brachial plexuses of 110 healthy volunteers were examined using high resolution color Doppler ultrasound. Ultrasonic characteristics and anatomic variation in the intervertebral foramen, interscalene, supraclavicular and infraclavicular, as well as the axillary brachial plexus were investigated. Results confirmed that the normal brachial plexus on cross section exhibited round or elliptic hypoechoic texture. Longitudinal section imaging showed many parallel linear hypo-moderate echoes, with hypo-echo. The transverse processes of the seventh cervical vertebra, the scalene space, the subclavian artery and the deep cervical artery are important markers in an examination. The display rates for the interscalene, and supraclavicular and axillary brachial plexuses were 100% each, while that for the infraclavicular brachial plexus was 97%. The region where the normal brachial plexus root traversed the intervertebral foramen exhibited a regular hypo-echo. The display rate for the C5-7 nerve roots was 100%, while those for C8 and T1 were 83% and 68%, respectively. A total of 20 of the 110 subjects underwent cervical CT scan. High-frequency ultrasound can clearly display the outline of the transverse processes of the vertebrae, which were consistent with CT results. These results indicate that high-frequency ultrasound provides a new method for observing the morphology of the brachial plexus. The C~ vertebra is a marker for identifying the position of brachial plexus nerve roots.

Influence of species,age and weight on the establishment of a murine model of brachial plexus root avulsion

BACKGROUND： Animal models of brachial plexus root avulsion are required for the study of brachial plexus root injuries. The established ventral approach results in slight injuries, and is similar to mechanisms underlying human brachial plexus root avulsion.OBJECTIVE： To analyze the effects of weight, age, and species on the success rate of brachial plexus root avulsion, and to determine the perfect method for establishing models of brachial plexus root avulsion.DESIGN, TIME AND SETTING： A randomized, block design was performed at the Laboratory of Professor Lihua Zhou, Zhongshan School of Medicine, Sun Yat-sen University, China from June 2008 to June 2009.MATERIALS： Sprague Dawley （SD） rats, golden hamsters, and BALb/C mice were used in the present study.METHODS： All animals were randomly subjected to classical brachial plexus root avulsion and modified brachial plexus root avulsion.MAIN OUTCOME MEASURES： Success rate of brachial plexus root avulsion. RESULTS： The success rate of brachial plexus root avulsion was greater in the modified group than in the classical group （P〈0.01）. Moreover, the difference was significant in 15-day-old SD rats, 5-week-old SD rats, and 3-month-old BALb/C mice （P〈0.01）. The success rate of brachial plexus root avulsion was greater in the same weight, 15-day-old juvenile SD rats, than in the 3-month-old BALb/C mice （classical group, P〈0.01; modified group, P〈0.05）. The success rate of brachial plexus root avulsion was significantly greater in 3-month-old golden hamsters than in 5-week-old SD rats in the classical group （P〈0.05）. The success rate of brachial plexus root avulsion was significantly lower in the 15-day-old SD rats compared with the 5-week-old and 3-month-old SD rats in the classical group （P〈0.01）. However, there was no significant difference in the success rate of brachial plexus root avulsion between various ages of SD rats in the modified group （P〉0.05）.CONCLUSION： Modified surgery to induce brachial plexus root avulsion significantly increases the success rate of model establishment. Species, age, and weight affect the success rate of brachial plexus root avulsion, and species plays an important role in the success rate.

A novel extradural nerve transfer technique by coaptation of C4 to C5 and C7 to C6 for treating isolated upper trunk avulsion of the brachial plexus

The study aimed to demonstrate the feasibility of an extradural nerve anastomosis technique for the restoration of a C5 and C6 avulsion of the brachial plexus.Nine fresh frozen human cadavers were used.The diameters,sizes,and locations of the extradural spinal nerve roots were observed.The lengths of the extradural spinal nerve roots and the distance between the neighboring nerve root outlets were measured and compared in the cervical segments.In the spinal canal,the ventral and dorsal roots were separated by the dura and arachnoid.The ventral and dorsal roots of C7 had sufficient lengths to anastomose those of C6.The ventral and dorsal of C4 had enough length to be transferred to those of C5,respectively.The feasibility of this extradural nerve anastomosis technique for restoring C5 and C6 avulsion of the brachial plexus in human cadavers was demonstrated in our anatomical study.

An electroencephalography-based human-machine interface combined with contralateral C7 transfer in the treatment of brachial plexus injury

Transferring the contralateral C7 nerve root to the median or radial nerve has become an important means of repairing brachial plexus nerve injury.However,outcomes have been disappointing.Electroencephalography(EEG)-based human-machine interfaces have achieved promising results in promoting neurological recovery by controlling a distal exoskeleton to perform functional limb exercises early after nerve injury,which maintains target muscle activity and promotes the neurological rehabilitation effect.This review summarizes the progress of research in EEG-based human-machine interface combined with contralateral C7 transfer repair of brachial plexus nerve injury.Nerve transfer may result in loss of nerve function in the donor area,so only nerves with minimal impact on the donor area,such as the C7 nerve,should be selected as the donor.Single tendon transfer does not fully restore optimal joint function,so multiple functions often need to be reestablished simultaneously.Compared with traditional manual rehabilitation,EEG-based human-machine interfaces have the potential to maximize patient initiative and promote nerve regeneration and cortical remodeling,which facilitates neurological recovery.In the early stages of brachial plexus injury treatment,the use of an EEG-based human-machine interface combined with contralateral C7 transfer can facilitate postoperative neurological recovery by making full use of the brain’s computational capabilities and actively controlling functional exercise with the aid of external machinery.It can also prevent disuse atrophy of muscles and target organs and maintain neuromuscular junction effectiveness.Promoting cortical remodeling is also particularly important for neurological recovery after contralateral C7 transfer.Future studies are needed to investigate the mechanism by which early movement delays neuromuscular junction damage and promotes cortical remodeling.Understanding this mechanism should help guide the development of neurological rehabilitation strategies for patients with brachial plexus injury.

Intraneural ganglion cyst of the lumbosacral plexus mimicking L5 radiculopathy:A case report

BACKGROUND Intraneural ganglion cysts are benign gelatinous masses that form within the epineurium of a peripheral nerve.Only few cases of intraneural ganglion cyst arising from the hip joint have been reported.CASE SUMMARY A previously healthy 65-year-old woman who had been experiencing left buttock pain radiating to the dorsum of the foot for 2 years visited our clinic.Prior to visiting the clinic,she underwent lumbar spine magnetic resonance imaging and received physiotherapy,pain killers,and epidural injections based on a presumptive diagnosis of spinal stenosis for 2 years in other hospitals.Repeat magnetic resonance imaging revealed joint connection of the articular branch of the hip joint and rostral extension of the cyst along the L5 spinal nerve near the L5-S1 neural foramen.The patient was diagnosed with intraneural ganglion cyst arising from the articular branch of the hip joint based on high-resolution magnetic resonance neurography.Using the arthroscopic approach,a cystic opening within the intra-articular space was detected,and cyst decompression was then performed.The pain in the left leg was significantly relieved during the 6-mo follow-up.CONCLUSION Although intraneural ganglion cysts arising from the hip joint are rare,they can cause typical radicular pain and mimic common L5 radiculopathy.Typical cyst ascent phenomenon starting from the termination of the articular branch on magnetic resonance imaging is a crucial finding indicative of intraneural ganglion cysts arising from the hip joint.

OBSERVATION ON EFFECT OF POINT INJECTION AS THE MAIN TREATMENT FOR OBSTETRIC BRACHIAL PLEXUS PALSY

To discuss the best way of treatment for obstetric brachial plexus palsy （OBPP）. Method： The 102 cases of OBPP were randomized into two groups： the observation group （51 cases） and the control group （51 cases）. The observation group was treated by point injection with nerve growth factor （NGF）, acupuncture, and moxibustion. The control group was treated by acupuncture and moxibustion. Result： The result was compared after two courses of treatment. The curative rate of observation group was 35.3% and that of control group 11.8%. The curative and remarkably effective rate was 78.4% and 43.2% respectively. In the two-two comparison, the difference was significant （ P〈 0. 01 ）. Conclusion： The effect of NGF point injection as the main treatment for OBPP was good, worth spreading.

Modified contralateral C7 nerve transfer: the possibility of permitting ulnar nerve recovery is confirmed by 10 cases of autopsy

Contralateral C7 nerve transfer surgery is one of the most important surgical techniques for treating total brachial plexus nerve injury. In the traditional contralateral C7 nerve transfer surgery, the whole ulnar nerve on the paralyzed side is harvested for transfer, which completely sacrifices its potential of recovery. In the present, novel study, we report on the anatomical feasibility of a modified contralateral C7 nerve transfer surgery. Ten fresh cadavers (4 males and 6 females) provided by the Department of Anatomy, Histology, and Embryology at the Medical College of Fudan University, China were used in modified contralateral C7 nerve transfer surgery. In this surgical model, only the dorsal and superficial branches of the ulnar nerve and the medial antebrachial cutaneous nerve on the paralyzed side (left) were harvested for grafting the contralateral (right) C7 nerve and the recipient nerves. Both the median nerve and deep branch of the ulnar nerve on the paralyzed (left) side were recipient nerves. To verify the feasibility of this surgery, the distances between each pair of coaptating nerve ends were measured by a vernier caliper. The results validated that starting point of the deep branch of ulnar nerve and the starting point of the medial antebrachial cutaneous nerve at the elbow were close to each other and could be readily anastomosed. We investigated whether the fiber number of donor and recipient nerves matched one another. The axons were counted in sections of nerve segments distal and proximal to the coaptation sites after silver impregnation. Averaged axon number of the ulnar nerve at the upper arm level was approximately equal to the sum of the median nerve and proximal end of medial antebrachial cutaneous nerve (left: 0.94:1;right: 0.93:1). In conclusion, the contralateral C7 nerve could be transferred to the median nerve but also to the deep branch of the ulnar nerve via grafts of the ulnar nerve without deep branch and the medial antebrachial cutaneous nerve. The advantage over traditional surgery was that the recovery potential of the deep branch of ulnar nerve was preserved. The study was approved by the Ethics Committee of Fudan University (approval number: 2015-064) in July, 2015.