Complete Nerve Transection Research Articles

Biocompatible 3D-Printed Devices With Adipose Stem Cells in the Regenerative Process of Sciatic Nerve Lesions in Rodent Models: An Experimental Study.

Peripheral nerve injuries are a significant clinical challenge. The rat sciatic nerve serves as an ideal model for studying nerve regeneration. Extensive research has been conducted to unravel the intricate mechanisms involved in peripheral nerve regeneration, aiming to develop effective therapeutic strategies for nerve injury patients. Research including different types of materials that can be used as nerve guides like synthetic polymershave been investigated for their biocompatibility and molding properties. Among multiple stem cell types, adipose-derived stem cells (ASCs), bone marrow-derived mesenchymal stem cells (BM-MSCs), and induced pluripotent stem cells (iPSCs) have shown neuroprotective and regenerative important properties. The purposes of our study were to develop a protocol for rat sciatic nerve injury treated with 3D-printed guide and adipose stem cells to investigate nerve regeneration through histologic examination and biomechanical characteristics of muscular tissue. We use 20 (100%) male Wistar rats, measuring between 350 g ± 35 g, whounderwent complete transection of the right sciatic nerve, resulting in a 1 cm defect. The group was separated into three subgroups: the first subgroup (n = 8) was treated with a 3D-printed guide with adiposestem cells, the second subgroup (n = 8) was treated with a 3D-printed guide without adiposestem cells, and the third subgroup (n = 4) was the control group. At four, eight, and 12 weeks, we measured with ultrasonography the grade of muscular atrophy. At 12 weeks, we harvested the sciatic nerve and performed a histological examination and mechanical investigation of the tibialis anterior muscle. On the examined specimen of the first subgroup, cross-sectioned nerve structures were present, surrounded by a mature fibro-adipose connective tissue, with blood vessels. In the second subgroup, no nerve structure was observed on the examined sections, but in the polymorphic inflammatory infiltrate and control group, no signs of regeneration were found. The present study shows a promising potential when utilizing adipose stem cell-based therapies for promoting peripheral nerve regeneration following large (>1 cm) nerve defects knowing that at this size, regeneration is impossible with known treatments.

Primary Radial Nerve Lesions in Humerus Shaft Fractures-Revision or Wait and See.

Background: This study investigates the surgical state-of-the-art procedure for humeral shaft fractures with primary radial nerve palsy based on its own case series in relation to the current and established literature. Methods: Retrospective review of treated cases between January 2018 and December 2022 describing radial nerve palsy after humerus shaft fractures, radiological fracture classification, intraoperative findings, surgical procedure, patient follow-up and functional outcome. Results: A total of 804 patients (463 women and 341 men) with humerus shaft fractures were identified. A total of 33 patients showed symptomatic lesions of the radial nerve (4.1%). The primary lesion was identified in 17 patients (2.1%). A broad and inhomogeneous distribution of fractures according to the AO classification was found. According to the operative reports, the distraction of the radial nerve was found eleven times, bony interposed three times and soft tissue constricted/compressed three times. In every case the radial nerve was surgically explored, there was no case of complete traumatic nerve transection. Four intramedullary nails and thirteen locking plates were used for osteosynthesis. Complete recovery of nerve function was seen in 12 cases within 1 to 36 months. Three patients still showed mild hypesthesia in the thumb area after 18 months. Two patients were lost during follow-up. Conclusions: With this study, we support the strategy of early nerve exploration and plate osteosynthesis in humeral fractures with primary radial nerve palsy when there is a clear indication for surgical fracture stabilisation. In addition, early exploration appears sensible in the case of palsies in open fractures and secondary palsy following surgery without nerve exposure as well as in the case of diagnostically recognisable nerve damage. Late nerve exploration is recommended if there are no definite signs of recovery after 6 months. An initial wait-and-see strategy with clinical observation seems reasonable for primary radial nerve palsies without indication for surgical fracture stabilisation.

Rat ventral caudal nerve as a model for long distance regeneration

In the rat, tail nerves are the longest peripheral nerves in their body. We suggest that ventral caudal nerve (VCN) may serve as a model for studying nerve injury and long distance regeneration. For this purpose, we have studied the anatomy and morphometry of the VCN in control animals. 10 cm long segment of the VCN was removed, and transversal sections were collected at 10 mm distances. The myelinated axons were counted, and the series of data were used to characterize the craniocaudal tapering of the nerve. In a separate group of animals, retrograde tracing with Fluorogold was used to localize and quantitate the spinal neurons projecting their axons into the VCN. After complete nerve transection, the time course of histopathological changes in the distal segment was studied. The primary goal was to define the time needed for axonal disintegration. In later periods, axonal debris removal and rearrangement of tissue elements was documented. After compression injury (axonotmesis), Wallerian degeneration was followed by spontaneous regeneration of axons. We show that the growing axons will span the 10 cm distance within 4–8 weeks. After different survival periods, the numbers of regenerating axons were counted at 10 mm distances. These data were used to characterize the dynamics of axonal regeneration during 4 months’ survival period. In the present study we show that axonal regeneration across 10 cm distance can be studied and quantitatively analyzed in a small laboratory animal.

Surgical management and the prognosis of iatrogenic facial nerve injury in middle ear surgery: a 20-year experience

BackgroundIatrogenic facial nerve injury is one of the severest complications of middle ear surgery, this study aims to evaluate surgical management and prognosis in the era of improved surgical instruments.MethodsPatients suffered from facial nerve paralysis after middle ear surgery between January 2000 and December 2019 were retrospectively collected. Demographic characters, primary disease and surgery, details of revision surgery were analyzed.ResultsForty-five patients were collected, of whom 8 were injured at our center and 37 were transferred.For 8 patients injured at our center, seven (87.5%) ranked House-Brackmann (H-B) grade V and one (12.5%) ranked H-B VI before revision surgery; postoperatively, two (25.0%) patients recovered to H-B grade I, four (50.0%) recovered to H-B II, and the other two (25.0%) recovered to H-B III. For 37 patients transferred, thirteen (35.1%) ranked H-B grade V and 24 (64.9%) ranked H-B VI preoperatively, final postoperative grade ranked from H-B grade I to grade V, with H-B I 6 (16.2%) cases, H-B II 6 (16.2%) cases, H-B III 18 (48.6%) cases, H-B IV 5 (13.5%) cases and H-B V 2 (5.4%) cases. The most vulnerable site was tympanic segment (5, 62.5% and 27, 73.0% respectively). Twenty-one (46.7%) patients suffered from mild injury and 24 (53.3%) suffered from partial or complete nerve transection. For surgical management, twenty-one (46.7%) patients received decompression, nineteen (42.2%) received graft and 5 (11.1%) received anastomosis. Those decompressed within 2 months after paralysis had higher possibility of H-B grade I or II recovery (P = 0.026), those received graft within 6 months were more likely to get H-B grade III recovery (P = 0.041), and for patients underwent anastomosis within 6 months, all recovered to H-B grade III.ConclusionsTympanic segment is the vulnerable site. If facial nerve paralysis happens, high-resolution computed tomography could help identify the injured site. Timely treatment is important, decompression within 2 months after paralysis, graft and anastomosis within 6 months lead to better recovery.

Adipose-Derived Stem Cells and Tacrolimus Improve Nerve Regeneration in a Rat Sciatic Nerve Defect Model.

This study compared the effect of undifferentiated adipose-derived stem cells (ADSCs) vs tacrolimus (FK506) in peripheral nerve regeneration in a rat sciatic nerve complete transection model. Forty Wistar rats were equally distributed in four groups. In the SHAM surgery group, the sciatic nerve was exposed and no further intervention was done. In the conduit-alone group (the SLN group), a 10-mm nerve gap was created and bridged with a fibrin conduit filled in with normal saline. In the FK506 group, the fibrin conduit was injected with soluble FK506. In the ADSC group, the conduit was impregnated with undifferentiated ADSCs. Nerve regeneration was assessed by means of walking track analysis, electromyography, and neurohistomorphometry. Clinically and microscopically, nerve regeneration was achieved in all groups at 12 weeks. Walking track analysis confirmed functional recovery in the FK506 and ADSC groups, but there was no difference between them. Recovery in function was also achieved in the SLN group, but it was inferior (P<.05). Electromyography demonstrated superior nerve regeneration in the FK506 and ADSC groups compared with the SLN group (P<.05), with no difference between the FK506 and ADSC groups. Similarly, histology showed no difference between the FK506 and ADSC groups, although both outperformed the SLN group (P<.05). No complications were observed. Successful peripheral nerve regeneration can be accomplished after a 10-mm nerve defect treated with nerve conduits. Superior nerve regeneration may be expected when the conduits are loaded with undifferentiated ADSCs or FK506, with similar outcomes for ADSCs and FK506. [Orthopedics. 2023;46(6):e353-e361.].

A systematic review of nerve grafting, end-to-end repair, and nerve transfer for obturator nerve injuries

ObjectiveObturator nerve injury can occur as a complication of gynecologic surgeries, occurring most frequently in patients with endometriosis and genitourinary malignancies. The resulting injury causes paresthesia and major weakness in...

Surfboard Related Orbital and Periocular Injury.

The objective of this study is to present the complexity of surfboard related orbital and periocular injuries and to discuss the different prevention aspects of such injuries. A retrospective review was performed on surfing related orbital and periocular injuries cases in a single tertiary medical center over a period of 10 years. Six patients at a mean age of 34 (range 20-50) years were evaluated. All were amateur surfers. Five patients had an orbital fracture, 3 had a full thickness eyelid laceration, 3 had lacrimal drainage system damage and 3 had intraocular findings related to trauma, but no perforation of the globe was observed. Two patients had complete optic nerve avulsion or transection, 1 of them had extraocular muscle transection. Five patients underwent surgery and 2 required an additional surgical intervention. At the end of follow-up, 3 patients had an unrepairable lacrimal drainage damage, 2 had a malposition of an eyelid, 2 eyes remained blind, 1 patient had a hypoglobus, and 1 had hypoesthesia in distribution of infraorbital nerve. Surfboard related orbital injuries may cause a severe orbital injury, which may debilitate and disable a previously active and healthy group of young people. Hence, protective gear wear should be more vigorously encouraged as already been done in other sports.

Optic chiasmatic potential by endoscopically implanted skull base microinvasive biosensor: a brain-machine interface approach for anterior visual pathway assessment.

Background: Visually evoked potential (VEP) is widely used to detect optic neuropathy in basic research and clinical practice. Traditionally, VEP is recorded non-invasively from the surface of the skull over the visual cortex. However, its trace amplitude is highly variable, largely due to intracranial modulation and artifacts. Therefore, a safe test with a strong and stable signal is highly desirable to assess optic nerve function, particularly in neurosurgical settings and animal experiments.Methods: Minimally invasive trans-sphenoidal endoscopic recording of optic chiasmatic potential (OCP) was carried out with a titanium screw implanted onto the sphenoid bone beneath the optic chiasm in the goat, whose sphenoidal anatomy is more human-like than non-human primates.Results: The implantation procedure was swift (within 30 min) and did not cause any detectable abnormality in fetching/moving behaviors, skull CT scans and ophthalmic tests after surgery. Compared with traditional VEP, the amplitude of OCP was 5-10 times stronger, more sensitive to weak light stimulus and its subtle changes, and was more repeatable, even under extremely low general anesthesia. Moreover, the OCP signal relied on ipsilateral light stimulation, and was abolished immediately after complete optic nerve (ON) transection. Through proof-of-concept experiments, we demonstrated several potential applications of the OCP device: (1) real-time detector of ON function, (2) detector of region-biased retinal sensitivity, and (3) therapeutic electrical stimulator for the optic nerve with low and thus safe excitation threshold.Conclusions: OCP developed in this study will be valuable for both vision research and clinical practice. This study also provides a safe endoscopic approach to implant skull base brain-machine interface, and a feasible in vivo testbed (goat) for evaluating safety and efficacy of skull base brain-machine interface.

Negative Pressure Neurogenesis: A Novel Approach to Accelerate Nerve Regeneration after Complete Peripheral Nerve Transection.

Background:Various modalities to facilitate nerve regeneration have been described in the literature with limited success. We hypothesized that negative pressure applied to a sectioned peripheral nerve would enhance nerve regeneration by promoting angiogenesis and axonal lengthening.Methods:Wistar rats’ sciatic nerves were cut (creating ~7 mm nerve gap) and placed into a silicone T-tube, to which negative pressure was applied. The rats were divided into 4 groups: control (no pressure), group A (low pressure: 10 mm Hg), group B (medium pressure: 20/30 mm Hg) and group C (high pressure: 50/70 mm Hg). The nerve segments were retrieved after 7 days for gross and histological analysis.Results:In total, 22 rats completed the study. The control group showed insignificant nerve growth, whereas the 3 negative pressure groups showed nerve growth and nerve gap reduction. The true nerve growth was highest in group A (median: 3.54 mm) compared to group B, C, and control (medians: 1.19 mm, 1.3 mm, and 0.35 mm); however, only group A was found to be significantly different to the control group (**P < 0.01). Similarly, angiogenesis was observed to be significantly greater in group A (**P < 0.01) in comparison to the control.Conclusions:Negative pressure stimulated nerve lengthening and angiogenesis within an in vivo rat model. Low negative pressure (10 mm Hg) provided superior results over the higher negative pressure groups and the control, favoring axonal growth. Further studies are required with greater number of rats and longer recovery time to assess the functional outcome.

Differential effects of 4‐aminopyridine on nerve injury severity‐dependent functional recovery and muscle atrophy in mice

Peripheral nerve injury (PNI) represents a major public health problem that often leads to profound neurologic impairment, disuse muscle atrophy, and permanent disability. While the functional recovery following nerve transection and repair is disappointing, the impact of irreparable nerve gap remains poorly characterized. Recently we demonstrated a repurposing beneficial effect of 4-aminopyridine (4-AP), a potassium channel blocker, on the functional recovery and muscle atrophy after sciatic nerve crush injury in rodents. However, this effect of 4-AP is unknown in nerve transection and gap models. This study was designed to evaluate and compare the functional recovery and muscle atrophy between nerve transection and nerve gap models in the absence (saline) and presence of 4-AP treatment. Under deep anesthesia and aseptic conditions, complete nerve transection or nerve gap injury was performed in male C57BL/6 mice (n = 10/group). In novel Stepwise Nerve Transection and Glue (STG) group, right sciatic nerve was sequentially transected with fibrin gluing to prevent gap formation. In nerve gap model, a large gap was created by dissecting out 7 mm (Gap-7) of right sciatic nerve section where the proximal stump of the nerve was buried underneath the muscle with fibrin glue. Following surgery, 4-AP (40 µg, ip) or saline was given daily and sciatic function index (SFI) was determined weekly for 12 weeks to evaluate functional recovery. After 12 weeks, tibialis anterior (TA) muscles were harvested for wet weight and histomorphological analysis. To asses muscle atrophy, right TA (RTA) muscle mass is presented as a percentage of contralateral healthy left TA (LTA) muscle which was assigned 100%. We found that SFI in STG group significantly dropped from baseline -9.9±2.83 to -66±2.24 (P<0.001) on one week followed by a small but significant recovery after 2 weeks (-51±4.42; P<0.05 vs. week-1) and then a steady state level between 9-12 weeks (-63±4.33). In Gap-7 group, SFI also significantly dropped from -8.5±3.18 to -72.4±2.50 in one week (P<0.001) and continued to deteriorate until it reached a steady state level after 10 weeks (-89.7±2.51). 4-AP had no effect on the SFI recovery in either group. Muscle atrophy was more pronounced in Gap-7 group (28±2% of LTA, P<0.001) compared to STG group (89±1.5% of LTA, P<0.001). Similar to muscle mass, RTA muscle cross sectional area (CSA) and minimum ferret diameter (MFD) were also significantly smaller in Gap-7 group compared to STG group. Interestingly, 4-AP treatment caused a significantly better recovery in RTA muscle mass, CSA, and MFD in Gap-7 group compared to STG group. These preliminary findings demonstrate that post-injury functional recovery and muscle atrophy after PNI are directly related to the intervening nerve gap, and 4-AP exerts differential effects on functional recovery and muscle atrophy.

Recovery of sciatic nerve with complete transection in rats treated with leuprolide acetate: A gonadotropin-releasing hormone agonist

It has been reported that the Gonadotropin-releasing hormone (GnRH) and its agonist leuprolide acetate (LA) can act as promoters of nerve regeneration. The aim of this study is to evaluate the effect of LA in a complete transection model. Sciatic nerve injury (SNI) was performed using a complete nerve transection and immediately repaired by epineural sutures. Rats were divided into three groups: SHAM, SNI treated with LA (SNI + LA) or saline solution (SNI + SS) for 5 weeks. Sciatic nerve regeneration was evaluated by kinematic gait analyzes, electrophysiological, morphological and biochemical tests. SNI + LA group had a functional recovery in kinematic gait, an increase in ankle angle value and a faster walking speed, compound muscle action potential amplitude, nerve conduction velocity (NCV). Furthermore, the number of myelinated axons and microtubule-associated protein 2 (MAP-2) expression were also higher compared to SS group. In conclusion, LA treatment improves of gait, walking speed, NCV, axons morphometry and MAP-2 expression in rats with sciatic nerve complete transection. These results suggest that LA can be a potential treatment for peripheral nerve injuries.

Sheath-Preserving Optic Nerve Transection in Rats to Assess Axon Regeneration and Interventions Targeting the Retinal Ganglion Cell Axon.

Retinal ganglion cell (RGC) axons converge at the optic nerve head to convey visual information from the retina to the brain. Pathologies such as glaucoma, trauma, and ischemic optic neuropathies injure RGC axons, disrupt transmission of visual stimuli, and cause vision loss. Animal models simulating RGC axon injury include optic nerve crush and transection paradigms. Each of these models has inherent advantages and disadvantages. An optic nerve crush is generally less severe than a transection and can be used to assay axon regeneration across the lesion site. However, differences in crush force and duration can affect tissue responses, resulting in variable reproducibility and lesion completeness. With optic nerve transection, there is a severe and reproducible injury that completely lesions all axons. However, transecting the optic nerve dramatically alters the blood brain barrier by violating the optic nerve sheath, exposing the optic nerve to the peripheral environment. Moreover, regeneration beyond a transection site cannot be assessed without reapposing the cut nerve ends. Furthermore, distinct degenerative changes and cellular pathways are activated by either a crush or transection injury. The method described here incorporates the advantages of both optic nerve crush and transection models while mitigating the disadvantages. Hydrostatic pressure delivered into the optic nerve by microinjection completely transects the optic nerve while maintaining the integrity of the optic nerve sheath. The transected optic nerve ends are reapposed to allow for axon regeneration assays. A potential limitation of this method is the inability to visualize the complete transection, a potential source of variability. However, visual confirmation that the visible portion of the optic nerve has been transected is indicative of a complete optic nerve transection with 90-95% success. This method could be applied to assess axon regeneration promoting strategies in a transection model or investigate interventions that target the axonal compartments.

Histological evaluation of inferior alveolar nerve injury after osteotomy of mandibular buccal cortex using piezoelectric versus conventional rotary devices: a split-mouth randomised study in rabbits

Up until now, only a limited number of evidence-based studies with different results has evaluated traumatic nerve injury after maxillofacial surgery using piezoelectric devices versus rotary instruments. The present experiment was performed to evaluate damage to the inferior alveolar nerve (IAN), histologically, after osteotomy of the buccal cortex of the mandible using piezoelectric devices versus surgical handpieces. Forty rabbits underwent bilateral osteotomy of the mandibular buccal cortex. For the osteotomy of one side, piezoelectric devices were used, and for the other, conventional rotary handpieces. After cleavage of the osteotomised cortical bone segments, the exposed part of the IAN was excised and examined histologically for nerve injury. IAN damage was scored histologically from Grade 0 (no nerve damage) to Grade 4 (complete nerve transection). It was found that 25% and 17.5% of nerves had Grade 0; 17.5% and 10% had Grade 1; 25% and 20% had Grade 2; 17.5% and 27.5% had Grade 3; and 15% and 25% had Grade 4 injury in piezosurgery and rotary groups, respectively. Statistical analyses revealed no significant difference between groups in damage to the IAN. The present study showed that piezosurgery devices, similar to conventional rotary instruments, have the potential to cause severe nerve damage during surgery and should therefore be used with care.

Nerve Injuries in Hip and Knee Arthroplasty - Risk Factors, Diagnostic and Therapeutic Approaches

Iatrogenic nerve injuries are rare complications of total hip and knee arthroplasty, which may cause chronic pain and loss of function, severely affecting the patient's daily activities and quality of life. Nerves "at risk" include the sciatic nerve, the femoral nerve, the lateral femoral cutaneous nerve and the superior gluteal nerve during total hip arthroplasty, and the infrapatellar branch of the saphenous nerve as well as the peroneal nerve during total knee arthroplasty. Multiple procedure-related and patient-related factors have been identified to modify the risk of nerve injury in the course of lower limb joint replacement surgery. These include the surgeon's skills, the surgical approach, the type of implant fixation, the intraoperative positioning of the patient, as well as pre-existing scars, the patient's sex, age and comorbidities. Diagnostic and therapeutic approaches should be based on the aetiology of the lesion: iatrogenic nerve lesions can result from direct (compression or transection) and/or indirect (traction, ischemia) trauma. The majority of nerve injuries encountered in hip or knee arthroplasty has been referred to as "minor" nerve lesions, which generally respond very well to non-operative treatment. "Major" nerve lesions, such as complete motor nerve transection, may result in lifelong impairment. Any perioperatively encountered neurological deficit requires a meticulous diagnostic work-up and an individually tailored treatment strategy, respecting aetiology and anatomic site of the nerve lesion as well as the individual patient's needs and comorbidities.

Facial nerve repair utilizing intraoperative repair strategies.

ObjectivesTo determine whether functional and anatomical outcomes following suture neurorrhaphy are improved by the addition of electrical stimulation with or without the addition of polyethylene glycol (PEG).MethodsIn a rat model of facial nerve injury, complete facial nerve transection and repair was performed via (a) suture neurorrhaphy alone, (b) neurorrhaphy with the addition of brief (30 minutes) intraoperative electrical stimulation, or (c) neurorrhaphy with the addition electrical stimulation and PEG. Functional recovery was assessed weekly for 16 weeks. At 16 weeks postoperatively, motoneuron survival, amount of regrowth, and specificity of regrowth were assessed by branch labeling and tissue analysis.ResultsThe addition of brief intraoperative electrical stimulation improved all functional outcomes compared to suturing alone. The addition of PEG to electrical stimulation impaired this benefit. Motoneuron survival, amount of regrowth, and specificity of regrowth were unaltered at 16 weeks postoperative in all treatment groups.ConclusionThe addition of brief intraoperative electrical stimulation to neurorrhaphy in this rodent model shows promising neurological benefit in the surgical repair of facial nerve injury.Level of EvidenceAnimal study.

The surgical management of traumatic neuromas

Following injury to a peripheral nerve, a neuroma may form and cause severe debilitating neuropathic pain. End neuromas are the result of an amputation or are found at the proximal stump in a complete nerve transection or rupture. Neuromas-in-continuity follows traction or compression injury and may complicate repair of a nerve transection or rupture. Symptomatic neuromas should be assessed and treated by a peripheral nerve surgeon working within a multi-professional team. The objectives of the initial treatment should encompass pain management, psychological support and physical therapies with the aim of restoration of normal nerve response thresholds to afferent stimuli and optimisation of the perineuroma environment. Surgical intervention should be reserved for non-responders and in cases where reconstruction of nerve function is deemed essential for useful functional recovery and pain resolution.

Rapid continuous 3D printing of customizable peripheral nerve guidance conduits.

Engineered nerve guidance conduits (NGCs) have been demonstrated for repairing peripheral nerve injuries. However, there remains a need for an advanced biofabrication system to build NGCs with complex architectures, tunable material properties, and customizable geometrical control. Here, a rapid continuous 3D-printing platform was developed to print customizable NGCs with unprecedented resolution, speed, flexibility, and scalability. A variety of NGC designs varying in complexity and size were created including a life-size biomimetic branched human facial NGC. In vivo implantation of NGCs with microchannels into complete sciatic nerve transections of mouse models demonstrated the effective directional guidance of regenerating sciatic nerves via branching into the microchannels and extending toward the distal end of the injury site. Histological staining and immunostaining further confirmed the progressive directional nerve regeneration and branching behavior across the entire NGC length. Observational and functional tests, including the von Frey threshold test and thermal test, showed promising recovery of motor function and sensation in the ipsilateral limbs grafted with the 3D-printed NGCs.

Nerve wrap after end-to-end and tension-free neurorrhaphy attenuates neuropathic pain: A prospective study based on cohorts of digit replantation

The repair of injured peripheral nerve is still challenging for surgeons. The end-to-end and tension-free neurorrhaphy is the current gold standard for reconstruction after complete nerve transection without significant defect. The main objective of this study neurorrhaphy in digit replantation affects the sensory recovery and neuropathic pain in replanted digit. Total 101 patients who received replantation of single completely amputated digit were included for analysis in this study. In group I (n = 49), the digital nerves were repaired with end-to-end and tension-free neurorrhaphy and then wrapped into a tendon-derived collagen nerve conduit. In group II (n = 52), the digital nerves were repaired with end-to-end and tension-free neurorrhaphy only. The static two-point discrimination (s2PD) was performed to evaluate sensory recovery. Visual analog scale (VAS) scores of pain at rest and with exertion were measured respectively. The s2PD tests at three and six months after surgery did not show any significant difference between the two groups. The VAS scores at rest and with exertion of group I were significantly reduced compared with those of group II at three and six months after surgery. Thus, we concluded that nerve wrap into a collagen conduit after end-to-end and tension-free neurorrhaphy could attenuate neuropathic pain after digit replantation but have no benefit for sensory recovery.

Similar 2-point discrimination and stereognosia but better locognosia at long term with an independent home-based sensory reeducation program vs no reeducation after low-median nerve transection and repair

Study DesignProspective controlled study. IntroductionPrevious studies evaluated the effectiveness of sensory reeducation (SR) after peripheral nerve injury and repair. However, evidence for long-term clinical usefulness of SR is inconclusive. Purpose of the StudyThe purpose of this study is to compare the sensory results of patients with low-median nerve complete transection and microsurgical repair, with and without SR at long term. MethodsWe prospectively studied 52 consecutive patients (mean age, 36 years; range, 20-47 years) with low-median nerve complete transection and microsurgical repair. When reinnervation was considered complete with perception of vibration with a 256-cycles per second tuning fork (mean, 3.5 months after nerve injury and repair), the patients were sequentially allocated (into 2 groups [group SR, 26 patients, SR; group R, 26 patients, reassured on recovery without SR). SR was conducted in a standardized fashion, in 2 stages, as an independent home-based program: the first stage was initiated when reinnervation was considered complete, and included instruction in home exercises to identify familiar objects and papers of different roughness, and localization of light touch (eyes open and closed); the second stage was initiated when the patients experienced normal static and moving 2-point discrimination (2PD) at the index fingertip of injured hand, and included instruction in home exercises for stereognosia, supplementary exercises for localization of light touch, and identification of small objects (eyes open and closed). Exercises were prescribed for 5-10 minutes, 4 times per day. At 1.5, 3, and 6 years after nerve injury and repair, we evaluated the static and moving 2PD, stereognosia with the Moberg's pick-up test, and locognosia with the modified Marsh test. Comparison between groups and time points was done with the nonparametric analysis of variance (Kruskal-Wallis analysis of variance). ResultsStatic and moving 2PD and stereognosia were not significantly different between groups at any study period. Locognosia was significantly better at 1.5 and 3 years in group SR; locognosia was excellent in 17 patients of group SR vs 5 patients of group R at 1.5-year follow-up and in 14 patients of group SR vs 5 patients of group R at 3-year follow-up. Locognosia was not different between the study groups at 6-year follow-up. ConclusionA 2-stage home program of SR improved locognosia at 1.5 and 3 years after low-median nerve complete transection and repair without significant differences in other modalities or the 6-year follow-up of a small subsample.

Partial Optic Nerve Transection in Rats: A Model Established with a New Operative Approach to Assess Secondary Degeneration of Retinal Ganglion Cells

Previous studies have shown that the secondary degeneration of retinal ganglion cells (RGCs) occurs commonly in glaucoma. Partial optic nerve transection is considered a useful and reproducible model. Compared with other optic nerve injury models used commonly for assessing secondary degeneration, e.g. complete optic nerve transection and optic nerve crush models, the partial optic nerve transection model is superior as it distinguishes primary from secondary degeneration in situ. Therefore, it serves as an excellent tool for evaluating secondary degeneration. This study describes a novel operative approach of partial optic nerve transection by directly accessing the area of the retrobulbar optic nerve through the orbital lateral wall of the eyeball. Moreover, we present a newly designed, low cost surgical instrument to assist with transection. As demonstrated by the representative results in distinguishing the boundary of primary and secondary injury areas, the new approach and instrument ensures high efficiency and stability of the model by providing adequate space for surgical operation. This in turn makes it easy to separate the meningeal sheath and ophthalmic vessels from the optic nerve before transection. An additional benefit is that this space-saving operative approach improves the investigators' ability to administer drugs, carriers, or selective RGC tracers to the stump of the partially transected optic nerve, allowing the exploration of mechanisms behind secondary injury in RGCs, in a new way.