Sensory Nerve Recovery Research Articles

Inferior Long-Term Results of a Randomized Controlled Trial Initially Demonstrating Enhanced Sensory Nerve Recovery Using a Chitosan Nerve Tube.

Traumatic peripheral nerve injuries can result in significant functional impairments and long-term sequelae. This study evaluated the long-term outcomes of a chitosan tube implant to protect epineural coaptation after peripheral nerve injuries using 2 different tube versions (different wall thicknesses and resorption characteristics), compared with a control group. The study focused on pain levels, sensory function, and overall functional outcomes. Patients who received a tube implant around direct coaptation sites of digital nerves were randomized and compared with control patients with no additional tube protection. Pain levels, sensory function, grip force, and functional scores were assessed at time points ranging from 3 months to 5 years postoperatively. Tube biodegradation was measured using high-resolution magnetic resonance neurography and categorized. Patients with the first tube version had higher pain levels compared with the control group after 5 years, and reported more symptoms of numbness and hypersensitivity. Patients with the second version exhibited higher pain levels at 3 months that did not persist at 6 months, but they showed compromised sensory function, with higher 2-point discrimination values compared with the first and control groups. No differences were found in grip force or functional scores between the groups. Magnetic resonance imaging displayed remnants of implants even at long-term follow-up. The findings suggest potential limitations attributable to increased pain and impaired sensory function associated with tube implantation in the long term. In the short term, however, the material seemed to have a protective effect (as published previously). The resorption process was not complete at the end of the 5-year observation period. This might explain the prolonged scarring and inferior long-term results. Future research should focus on improving tube materials and design to minimize adverse effects and enhance functional outcomes.

Analysis of Effect of Melatonin on Postoperative Sensory Nerve Recovery Following Open Reduction and Internal Fixation of Anterior Mandible Fractures: A Prospective Randomized Control Trial.

Open reduction and internal fixation (ORIF) of the anterior mandibular fractures are commonly associated with mental nerve paraesthesia. This study evaluates the efficacy of melatonin on postoperative sensory functional recovery and pain following surgical treatment of anterior mandibular fractures. Forty patients were randomly allocated to two groups: Group I-melatonin, and Group II-control group. Postoperative neurosensory recovery was evaluated both subjectively and objectively at 1-week, 1-month, and 3-month intervals. The pain was assessed during the immediate postoperative period, postoperative days 1, 2, 3, and 7 using a visual analog scale. Statistical significance was set at P value < 0.05. The statistically significant difference was noticed in both subjective and objective recovery of sensory nerve function at 1-month follow-up. All patients in the melatonin group showed complete recovery of nerve function as compared to the control group where 10% of patients showed limited recovery. Neurosensory recovery following ORIF of mandibular fractures was better in the melatonin group as compared to the control group and therefore the perioperative administration of 10mg. Melatonin can be recommended for quicker and better nerve recovery in the anterior mandibular fractures requiring close manipulation of the mental nerve during treatment.

Nerve Regeneration Using Polyglycolic Acid-Collagen Tube Following Tumor Resection in The Inferior Alveolar Nerve

A conduit for peripheral nerve regeneration (NERBRIDGE®; Toyobo Co., Japan) in cases of disconnection or deficiency of the peripheral nerve was approved in Japan in 2013. NERBRIDGE® is a polyglycolic acid-collagen (PGA) product derived from porcine skin. The use of NERBRIDGE® has been reported mainly in orthopaedic surgery. Reports on its use for sensory nerve injuries in the oral region are scarce. This case report describes a case of significant sensory recovery obtained by nerve repair using NERBRIDGE® in a patient with schwannoma-induced inferior alveolar nerve resection. At the 1-year postoperative evaluation, sensory nerve recovery using the two-point discrimination test was confirmed.

Precise Monitoring of Returning Sensation in Digital Nerve Lesions by 3-D Imaging: A Proof-of-Concept Study.

Digital nerve lesions result in a loss of tactile sensation reflected by an anesthetic area (AA) at the radial or ulnar aspect of the respective digit. Yet, available tools to monitor the recovery of tactile sense have been criticized for their lack of validity. However, the precise quantification of AA dynamics by three-dimensional (3-D) imaging could serve as an accurate surrogate to monitor recovery following digital nerve repair.For validation, AAs were marked on digits of healthy volunteers to simulate the AA of an impaired cutaneous innervation. Three dimensional models were composed from raw images that had been acquired with a 3-D camera (Vectra H2) to precisely quantify relative AA for each digit (3-D models, n= 80). Operator properties varied regarding individual experience in 3-D imaging and image processing. Additionally, the concept was applied in a clinical case study.Images taken by experienced photographers were rated better quality (p< 0.001) and needed less processing time (p= 0.020). Quantification of the relative AA was neither altered significantly by experience levels of the photographer (p= 0.425) nor the image assembler (p= 0.749).The proposed concept allows precise and reliable surface quantification of digits and can be performed consistently without relevant distortion by lack of examiner experience. Routine 3-D imaging of the AA has the great potential to provide visual evidence of various returning states of sensation and to convert sensory nerve recovery into a metric variable with high responsiveness to temporal progress.

Comparative assessment of fingertip replantation in paediatric and adult patients within a single institution.

The purpose of this retrospective study was to compare the outcomes of paediatric and adult fingertip replantation within a single institution. Our retrospective study found no significant difference in the survival rate between the paediatric (10/12) and adult (22/26) groups. At 6months follow-up, there was no significant difference in sensory recovery between both groups, as measured with Semmes-Weinstein testing, but a significant difference in mean static two-point discrimination testing values between the paediatric (4.0 mm) and adult (6.2 mm) groups. Moreover, the mean time for regaining sensation was faster in paediatric patients (1.3months) as compared with adult patients (4.1months). Five children and four adults received erythrocyte transfusion. Paediatric fingertip replantation has similar survival rates, faster and better sensory nerve recovery as compared with adults despite a higher erythrocyte transfusion rate. Although technically demanding, paediatric fingertip replantation is recommended, whenever possible, because of the good outcomes achievable.Level of evidence: IV.

Safety and efficacy of a nerve matrix membrane as a collagen nerve wrapping: a randomized, single-blind, multicenter clinical trial.

A new nerve matrix membrane derived from decellularized porcine nerves has been shown to retain the major extracellular matrix components, and to be effective in preventing adhesion between the nerve anastomosis sites and the surrounding tissues in a rat sciatic nerve transection model, thereby enhancing regeneration of the nerve. The effectiveness of the membrane may be attributed to its various bioactive components. In this prospective, randomized, single-blind, parallel-controlled multicenter clinical trial, we compared the safety and efficacy of the new nerve matrix membrane with a previously approved bovine tendon-derived type I collagen nerve wrapping. A total of 120 patients with peripheral nerve injury were recruited from Beijing Jishuitan Hospital, The First Bethune Hospital of Jilin University, and Yantai Yuhuangding Hospital, China. The patients were randomly assigned to undergo end-to-end and tension-free neurorrhaphy with nerve matrix membrane (n = 60, 52 male, 8 female, mean age 41.34 years, experimental group) or tendon-derived collagen nerve wrapping (n = 60, 42 male, 18 female, mean age 40.17 years, control group). Patients were followed-up at 14 ± 5, 30 ± 7, 90 ± 10 and 180 ± 20 days after the operation. Safety evaluation included analyses of local and systemic reactions, related laboratory tests, and adverse reactions. Efficacy evaluation included a static 2-point discrimination test, a moving 2-point discrimination test, and a Semmes-Weinstein monofilament examination. Sensory nerve function was evaluated with the British Medical Research Council Scale and Semmes-Weinstein monofilament examination. The ratio (percentage) of patients with excellent to good results in sensory nerve recovery 180 ± 20 days after the treatment was used as the primary effectiveness index. The percentages of patients with excellent to good results in the experimental and control groups were 98.00% and 94.44%, respectively, with no significant difference between the two groups. There were no significant differences in the results of routine blood tests, liver and renal function tests, coagulation function tests, or immunoglobulin tests at 14 and 180 days postoperatively between the two groups. These findings suggest that the novel nerve matrix membrane is similar in efficacy to the commercially-available bovine-derived collagen membrane in the repair of peripheral nerve injury, and it may therefore serve as an alternative in the clinical setting. The clinical trial was approved by the Institutional Ethics Committee of Beijing Jishuitan Hospital, China (approval No. 20160902) on October 8, 2016, the Institutional Ethics Committee of the First Bethune Hospital of Jilin University, China (approval No. 160518-088) on December 14, 2016, and the Institutional Ethics Committee of Yantai Yuhuangding Hospital, China (approval No. 2016-10-01) on December 9, 2016. The clinical trial was registered with the Chinese Clinical Trial Registry (registration number: ChiCTR2000033324) on May 28, 2020.

Short- and long-term results of common peroneal nerve injuries treated by neurolysis, direct suture or nerve graft.

Damage to the common peroneal nerve is the most frequent nerve injury in lower limb traumas. Our objective was to assess the motor and sensory recovery levels and the functional outcomes after remedial surgery for common peroneal nerve trauma, through either neurolysis, direct suture or nerve graft. This is a transversal, observational study of a monocentric cohort of 20 patients who underwent surgery between January 2004 and June 2016, which included 16 men and 4 women whose median age was 35 ± 11years. We assessed the level of sensory and motor nerve recovery and the Kitaoka score. Nine patients benefited from neurolysis, 5 had direct sutures, and 6 received a nerve graft. With 48months' average follow-up, 7 out of 9 patients underwent neurolysis and 4 out of 5 with direct sutures had good motor recovery (≥ M4), but none for the grafts. Sensory recovery (≥ S3) was satisfactory in 7 out of 9 cases in the neurolysis group, 3 out of 5 in the direct suture group, and 3 out of 6 in the nerve graft group. The average Kitaoka score was 83.7 ± 11.5 for the neurolysis group, 86.8 ± 16 for the direct suture group, and 73 ± 14 for the graft group. Surgical treatment by neurolysis and direct suture yields good results with a motor recovery ratio nearing 80%. When a nerve graft becomes necessary, recovery is poor and resorting to palliative techniques in the shorter run is a strategy which should be evaluated.

Molecular basis of Mitomycin C enhanced corneal sensory nerve repair after debridement wounding

The ocular surface is covered by stratified squamous corneal epithelial cells that are in cell:cell contact with the axonal membranes of a dense collection of sensory nerve fibers that act as sentinels to detect chemical and mechanical injuries which could lead to blindness. The sheerness of the cornea makes it susceptible to superficial abrasions and recurrent erosions which demand continuous regrowth of the axons throughout life. We showed previously that topical application of the antibiotic and anticancer drug Mitomycin C (MMC) enhances reinnervation of the corneal nerves and reduces recurrent erosions in mice via an unknown mechanism. Here we show using RNA-seq and confocal imaging that wounding the corneal epithelium by debridement upregulates proteases and protease inhibitors within the epithelium and leads to stromal nerve disruption. MMC attenuates these effects after debridement injury by increasing serpine1 gene and protein expression preserving L1CAM on axon surfaces of reinnervating sensory nerves. These data demonstrate at the molecular level that gene expression changes in the corneal epithelium and stroma modulate sensory axon integrity. By preserving the ability of axons to adhere to corneal epithelial cells, MMC enhances sensory nerve recovery after mechanical debridement injury.

Can nerve regeneration on an artificial nerve conduit be enhanced by ethanol-induced cervical sympathetic ganglion block?

This study aimed to determine whether nerve regeneration by means of an artificial nerve conduit is promoted by ethanol-induced cervical sympathetic ganglion block (CSGB) in a canine model. This study involved two experiments—in part I, the authors examined the effect of CSGB by ethanol injection on long-term blood flow to the orofacial region; part II involved evaluation of the effect of CSGB by ethanol injection on inferior alveolar nerve (IAN) repair using polyglycolic acid-collagen tubes. In part I, seven Beagles were administered left CSGB by injection of 99.5% ethanol under direct visualization by means of thoracotomy, and changes in oral mucosal blood flow in the mental region and nasal skin temperature were evaluated. The increase in blood flow on the left side lasted for 7 weeks, while the increase in average skin temperature lasted 10 weeks on the left side and 3 weeks on the right. In part II, fourteen Beagles were each implanted with a polyglycolic acid-collagen tube across a 10-mm gap in the left IAN. A week after surgery, seven of these dogs were administered CSGB by injection of ethanol. Electrophysiological findings at 3 months after surgery revealed significantly higher sensory nerve conduction velocity and recovery index (ratio of left and right IAN peak amplitudes) after nerve regeneration in the reconstruction+CSGB group than in the reconstruction-only group. Myelinated axons in the reconstruction+CSGB group were greater in diameter than those in the reconstruction-only group. Administration of CSGB with ethanol resulted in improved nerve regeneration in some IAN defects. However, CSGB has several physiological effects, one of which could possibly be the long-term increase in adjacent blood flow.

Prognostic factors in sensory recovery after digital nerve repair.

The prognostic factors that affect sensory nerve recovery after digital nerve repair are variable because of nonhomogeneous data, subjective tests, and different assessment/scoring methods. The aim of this study was to evaluate the success of sensory nerve recovery after digital nerve repair and to investigate the prognostic factors in sensorial healing. Ninety-six digital nerve repairs of 63 patients were retrospectively evaluated. All nerves were repaired with end-to-end neurorraphy. The static two-point discrimination (s2PD) and Semmes Weinstein monofilament (SWM) tests were performed to evaluate sensory recovery. The association between prognostic factors such as gender, age, involved digit, time from injury to repair, length of follow-up, smoking, concomitant injuries, type of injury, and sensory recovery results were assessed. The s2PD test demonstrated excellent results in 26 nerves (27%), good results in 61 nerves (64%), and poor results in 9 nerves (9%). The results of the SWM test according to Imai classification showed that 31 nerves (32%) were normal, light touch was diminished in 38 nerves (40%), protective sensation was diminished in 17 nerves (18%), loss of protective sensation occurred in 5 nerves (5%), and 5 nerves (5%) were anesthetic. There was a negative relationship between age, smoking, concomitant injuries, and sensory recovery. Our results demonstrate that concomitant tendon, bone and vascular injuries, older age, and smoking were associated with worse sensory nerve recovery results. However, all digital nerve injuries should be repaired, regardless of these prognostic factors.

Natural history of sensory nerve recovery after cutaneous nerve injury following foot and ankle surgery.

Cutaneous nerve injury is the most common complication following foot and ankle surgery. However, clinical studies including long-term follow-up data after cutaneous nerve injury of the foot and ankle are lacking. In the current retrospective study, we analyzed the clinical data of 279 patients who underwent foot and ankle surgery. Subjects who suffered from apparent paresthesia in the cutaneous sensory nerve area after surgery were included in the study. Patients received oral vitamin B12 and methylcobalamin. We examined final follow-up data of 17 patients, including seven with sural nerve injury, five with superficial peroneal nerve injury, and five with plantar medial cutaneous nerve injury. We assessed nerve sensory function using the Medical Research Council Scale. Follow-up immediately, at 6 weeks, 3, 6 and 9 months, and 1 year after surgery demonstrated that sensory function was gradually restored in most patients within 6 months. However, recovery was slow at 9 months. There was no significant difference in sensory function between 9 months and 1 year after surgery. Painful neuromas occurred in four patients at 9 months to 1 year. The results demonstrated that the recovery of sensory function in patients with various cutaneous nerve injuries after foot and ankle surgery required at least 6 months.

A comparison between complete immobilisation and protected active mobilisation in sensory nerve recovery following isolated digital nerve injury

Post-operative immobilisation following isolated digital nerve repair remains a controversial issue amongst the microsurgical community. Protocols differ from unit to unit and even, as evidenced in our unit, may differ from consultant to consultant. We undertook a retrospective review of 46 patients who underwent isolated digital nerve repair over a 6-month period. Follow-up ranged from 6 to 18 months. Twenty-four were managed with protected active mobilisation over a 4-week period while 22 were immobilised over the same period. Outcomes such as return to work, cold intolerance, two-point discrimination and temperature differentiation were used as indicators of clinical recovery. Our results showed that there was no significant difference noted in either clinical assessment of recovery or return to work following either post-operative protocol, suggesting that either regime may be adopted, tailored to the patient's needs and resources of the unit.

Vein conduit associated with microsurgical suture for complete collateral digital nerve severance

The aim of this study is to present the long term results of a series of 53 vein conduit grafts as first line therapy to repair complete severance of one or more collateral digital nerves. The surgical technique included an epi-perineural suture of the nerve under minimal tension, associated with a vein graft harvested from the back of the hand to cover the nerve. None of the patients presented with a neuroma, spontaneous pain or had stopped using the injured finger. Sensibility results were good or very good in 67% of cases. The scar at the donor site was very light or invisible. A total of 96% of patients were satisfied or very satisfied. This simple technique, by protecting the injured nerve, results in a rate of sensory nerve recovery that is comparable or better than that of other series in the literature, without neuroma and with minimal scarring at the donor site.

Treatment of a Segmental Nerve Defect in the Rat with Use of Bioabsorbable Synthetic Nerve Conduits: A Comparison of Commercially Available Conduits

The use of biodegradable synthetic nerve conduits for the reconstruction of segmental nerve defects has been extensively reported in both animal and human studies, with a majority of studies evaluating sensory nerve recovery. However, few studies have compared these nerve conduits for functional motor recovery. The purpose of this study was to compare three commercially available, synthetic, bioabsorbable nerve conduits and autograft with respect to compound muscle action potentials, maximum isometric tetanic force, wet muscle weight, and nerve histomorphometry. Eighty Lewis rats were divided into four groups according to the type of repair of a 10-mm excision of the sciatic nerve: group I had a reversed autograft; group II, a poly-DL-lactide-epsilon-caprolactone conduit; group III, a type-I collagen conduit; and group IV, a polyglycolic acid conduit. All results were compared with the contralateral side. At twelve weeks, the rats underwent bilateral measurements of the compound muscle action potentials of the tibialis anterior and flexor digiti quinti brevis muscles, isometric tetanic force and muscle weight of the tibialis anterior, and peroneal nerve histomorphometry. At twelve weeks, no difference in the percentage of recovery between the autograft and the poly-DL-lactide-epsilon-caprolactone conduit was observed with respect to compound muscle action potentials, isometric muscle force, muscle weight, and axon count measurements. The poly-DL-lactide-epsilon-caprolactone and collagen conduits remained structurally stable at twelve weeks, while the polyglycolic acid conduits had completely collapsed. The polyglycolic acid conduit had the poorest results, with a recovery rate of 15% for compound muscle action potentials and 29% for muscle force. The functional outcome in this rat model was similar for the autograft and the poly-DL-lactide-epsilon-caprolactone conduits when they were used to reconstruct a 10-mm sciatic nerve defect. Functional recovery following the use of the polyglycolic acid conduit was the poorest.

경피신경전기자극과 전침자극이 흰쥐 좌골신경 압좌손상 후 척수내 c-fos 발현과 기능회복에 미치는 영향

본 연구는 흰쥐를 대상으로 좌골신경 압좌 손상 유발 후 경피신경전기자극과 전침자극을 적용하고 진통효과와 기능회복에 미치는 영향을 알아보았다. 실험동물은 경피신경전기자극군을 적용한 TENS군, 전침자극군을 적용한 EA군과 대조군으로 구분하였고, 각각의 군은 전기자극 적용기간에 따라 1일군, 7일군 및 14일군으로 나누었다. 경피신경자극과 전침자극을 적용한 결과, 실험군에서 대조군에 비하여 통각신경활성의 지표로 이용되는 c-fos 발현의 감소, 발도피지연시의 증가, 좌골신경기능지수의 증가를 통해 전기자극이 말초신경 손상에서 통증억제와 기능회복을 증가시키는 것으로 나타났다. 하지만 경피신경전기자극군과 전침자극군간의 유의한 차이는 관찰되지 않았다. The purpose of this study was to identify the effect of transcutaneous electrical nerve stimulation(TENS) and electroacupuncture(EA) after sciatic nerve crush injury in rats. Subjects were classified TENS group with TENS application, EA group with EA application and Control group which is not applicated electrical stimulation. TENS and EA stimulations were applied post-injury day(PD) 1 to 14 after sciatic nerve injury. This study observed c-fos expression in rat lumbar spinal cord. In addition, the paw withdrawal latency(PWL) and sciatic function index(SFI) were measured. The results were as follows: At PD 1, control group had higher c-fos immunoreactivity than experimental groups. At PD 7 and 14, control group had higher c-fos immunoreactivity than experimental groups. The PWL of experimental groups were significantly lower than control group. The SFI had not significant difference in all groups. But the average of experimental groups were higher than control group. These results suggest that TENS and EA applications increasing sensory and motor nerve recovery while decreasing c-fos immunoreactivity after sciatic nerve crush injury.

Functional Gait Evaluation of Collagen Chitosan Nerve Guides for Sciatic Nerve Repair

The objective of this work was to use a functional gait analysis technique to evaluate sciatic nerve repair through tissue-engineered nerve guides in a rodent animal model. The nerve guides were fabricated by blending collagen with chitosan material and evaluated over a 12-week period for motor and sensory nerve recovery assessed by gait analysis and behavioral testing. Gastrocnemius muscle weight measurements were obtained at the end of each experimental time point and correlated to motor nerve recovery. Functional gait analysis studied both the stance and swing phase angle formations during a normal gait cycle. During the stance phase, functional results revealed that blended nerve guides promoted increased motor nerve recovery than unblended chitosan nerve guides. Similar results were obtained from behavioral tests, indicating that blended nerve guides created increased sensitivity to applied stimulus compared to unblended nerve guides. Muscle strength also correlated with functional recovery and was significantly higher when compared to the unblended nerve guides. From this study, we conclude that collagen-blended chitosan nerve guides enhanced motor and sensory nerve recovery assayed through gait and behavioral testing compared to unblended nerve guides.

P079 Stimulus dependence of sensory nerve recovery cycles measured by threshold tracking

P079 Stimulus dependence of sensory nerve recovery cycles measured by threshold tracking

Acceleration of Sensory Neural Regeneration and Wound Healing with Human Mesenchymal Stem Cells in Immunodeficient Rats

The sensory nerve is highly involved in lower extremity wound healing. In diabetic and vascular diseases, impaired nerve function and blood flow delay wound healing. Tissue regeneration using adult stem cells is a targeted therapeutic modality in disorders of nerve and blood supply. Effective delivery using an autologous vascularized fascial flap as a vehicle of stem cells leads to severed sensory nerve recovery, local tissue blood flow, and wound healing. Human MSCs (hMSCs) were transfected with green fluorescent protein (GFP) cDNA and tested for efficiency and proliferation in vitro. The nude rat model with femoral vessel and saphenous nerve severance and ligation was wrapped with a vascularized epigastric flap for GFP-hMSC, fibroblast growth factor-2 (FGF-2), or a combination of both after 2 weeks. Maximum nerve conduction velocity recovered to 70% of the presurgical level in the GFP-hMSC- and FGF-2-treated group at 2 weeks. Blood flow and nerve conduction velocity were positively correlated at 1 week. Wound healing in the ipsilateral paw had significantly improved by 1 week. Histologically, blood vessels and nerves are very organized, and regenerated neuron immunoreactivity of GAP-43 and a nerve regrowth marker of S-100 were remarkable in the human GFP (hGFP)-hMSC and FGF-2-treated group at 2 weeks; therefore, sensory nerve regeneration, blood flow, and wound healing were improved by the administration of stem cells and FGF-2 via a vascularized flap. This may be implicated in clinical denervated and reduced circulation tissue wound healing.

Secondary Digital Nerve Repair in the Foot with Resorbable p(DLLA-ε-CL) Nerve Conduits

Nerve guides are increasingly being used in peripheral nerve repair. In the last decade, much preclinical research has been undertaken into a resorbable nerve guide composed of p(DLLA-epsilon-CL). This report describes the results of secondary digital nerve reconstruction in the foot in a patient with post-traumatic neuromas of the common plantar digital nerves II-III and III-IV. The neuromas were resected and reconstruction of the nerves was carried out with resorbable Neurolac nerve guides. The Pressure Specified Sensory Device was used to measure the static (s) and moving (m) 1- and 2-point discrimination (PD). Fourteen months after nerve repair, the m1-PD returned in all digital nerves. The s1-PD returned only on the lateral side of the second toe. The m2-PD and s2-PD did not return in any of the toes originally innervated by the reconstructed nerves. According to the British Classification System, the sensory nerve recovery was poor. However, there were no complaints of painful neuromas after this procedure. In conclusion, this report shows no beneficial effects of Neurolac nerve guides in terms of return of sensibility after repair of common plantar digital nerves. Painful neuromas, however, could be well-treated.

Long‐term effects of muscle‐derived protein with molecular mass of 77 kDa (MDP77) on nerve regeneration

The long-term effects of the 77-kDa muscle-derived protein (MDP77) on motor and sensory nerve regeneration were examined in vivo. Fourteen-millimeter bridge grafts of the right sciatic nerve of SD rats were carried out with silicone tubes containing a solution of type I collagen together with 0, 5, 10, or 20 microg/ml recombinant human MDP77 (N = 10 in each group). Recovery of motor and sensory function was evaluated monthly by the maximal toe-spread index (TSI) and hot-plate test, respectively, for 6 months after the operation. Electrophysiology (nerve conduction velocity), histology (diameter and total number of the regenerated myelinated axons in the tube), and immunohistochemistry (total number of Schwann cells in the tube), as well as measurement of soleus muscle weight, were also performed at this time. Motor, but not sensory, function recovered rapidly in the MDP77-treated groups in a dose-dependent manner. Electrophysiological measurements and the ratio of soleus muscle weight corroborated the positive effects of MDP77 on motor nerve regeneration, but no facilitation of sensory nerve recovery was observed. Furthermore, histological and immunohistochemical evaluations suggested that MDP77 treatment accelerates Schwann cell migration, followed by enhanced maturation of regenerating axons, resulting in functional recovery of both the nerves and the atrophied, denervated muscle.