Perineural Scar Formation Research Articles

Fibrin Glue Coating Limits Scar Tissue Formation around Peripheral Nerves.

Scar tissue formation presents a significant barrier to peripheral nerve recovery in clinical practice. While different experimental methods have been described, there is no clinically available gold standard for its prevention. This study aims to determine the potential of fibrin glue (FG) to limit scarring around peripheral nerves. Thirty rats were divided into three groups: glutaraldehyde-induced sciatic nerve injury treated with FG (GA + FG), sciatic nerve injury with no treatment (GA), and no sciatic nerve injury (Sham). Neural regeneration was assessed with weekly measurements of the visual static sciatic index as a parameter for sciatic nerve function across a 12-week period. After 12 weeks, qualitative and quantitative histological analysis of scar tissue formation was performed. Furthermore, histomorphometric analysis and wet muscle weight analysis were performed after the postoperative observation period. The GA + FG group showed a faster functional recovery (6 versus 9 weeks) compared to the GA group. The FG-treated group showed significantly lower perineural scar tissue formation and significantly higher fiber density, myelin thickness, axon thickness, and myelinated fiber thickness than the GA group. A significantly higher wet muscle weight ratio of the tibialis anterior muscle was found in the GA + FG group compared to the GA group. Our results suggest that applying FG to injured nerves is a promising scar tissue prevention strategy associated with improved regeneration both at the microscopic and at the functional level. Our results can serve as a platform for innovation in the field of perineural regeneration with immense clinical potential.

Nerve-End Capping Treatment with a Polyglycolic Acid Conduit for Rat Sciatic Neuroma: A Preliminary Report.

The treatment of painful neuroma remains challenging. Recently, a nerve-end capping technique using a bioabsorbable nerve conduit was newly introduced to treat amputation neuroma. A collagen-coated polyglycolic acid (PGA) conduit has been commercially available for the reconstruction of peripheral nerve defects, yielding successful clinical outcomes. However, no experimental research has been conducted using this PGA nerve conduit as capping device for treating amputation neuroma. The purpose of this study was to investigate nerve-end capping treatment with the PGA conduit in the rat sciatic nerve amputation model, focusing on histological scar formation and neuroinflammation. Forty-seven rats were divided into two groups: no capping (transected nerve stump without capping; n = 25) and capping (nerve-end capping with collagen-coated PGA nerve conduit; n = 22). Twelve weeks after sciatic neurectomy, neuropathic pain was evaluated using the autotomy score. Stump neuromas were histologically evaluated or perineural scar and neuroinflammation. While autotomy scores gradually exacerbated in both groups, they were consistently lower in the capping group at 4, 8, and 12 weeks postprocedure. Twelve weeks after surgery, the transected nerve stumps in the no-capping group had formed macroscopic bulbous neuromas strongly adhering to surrounding tissues, whereas they remained wrapped with the PGA nerve conduits loosely adhering to surrounding tissues in the capping group. Histologically, distal axonal fibers were expanded radially and formed neuromas in the no-capping group, while they were terminated within the PGA conduit in the capping group. Perineural scars and neuroinflammation were widely found surrounding the randomly sprouting nerve end in the no-capping group. In capped counterparts, scars and inflammation were limited to closely around the terminated nerve end. Nerve-end capping with a collagen-coated PGA conduit after rat sciatic neurectomy might prevent neuroma formation by suppressing perineural scar formation and neuroinflammation around the nerve stump, potentially relieving neuropathic pain.

Nerve capping with a nerve conduit for the treatment of painful neuroma in the rat sciatic nerve.

Treatment of painful neuroma remains difficult, despite the availability of numerous surgical procedures. Recently, nerve capping treatment for painful neuroma using artificial nerve conduits has been introduced in clinical and basic research. However, the appropriate length of the nerve conduit and the pain relief mechanism have not been determined. In this study the authors aimed to investigate nerve capping treatment with a bioabsorbable nerve conduit using the rat sciatic nerve amputation model. Using histological analysis, the authors focused on the nerve conduit length and pain relief mechanism. Sixteen Sprague Dawley rats were evaluated for neuropathic pain using an autotomy (self-amputation) score and gross and histological changes of the nerve stump 2, 4, 8, and 12 weeks after sciatic nerve neurectomy without capping. Forty-five rats were divided into 3 experimental groups, no capping (control; n = 15), capping with a 3-mm nerve conduit (n = 15), and capping with a 6-mm nerve conduit (n = 15). All rats were evaluated using an autotomy score and nerve stump histology 12 weeks after neurectomy. The nerve conduit was approximately 0.5 mm larger than the 1.5-mm diameter of the rat sciatic nerves to prevent nerve constriction. The autotomy scores gradually exacerbated with time. Without capping, a typical bulbous neuroma was formed due to random axonal regeneration 2 weeks after neurectomy. Subsequently, the adhesion surrounding the neuroma expanded over time for 12 weeks, and at the 12-week time point, the highest average autotomy scores were observed in the no-capping (control) group, followed by the 3- and the 6-mm nerve conduit groups. Histologically, the distal axonal fibers became thinner and terminated within the 6-mm nerve conduit, whereas they were elongated and protruded across the 3-mm nerve conduit. Minimal perineural scar formation was present around the terminated axonal fibers in the 6-mm nerve conduit group. Expressions of anti-α smooth muscle actin and anti-sigma-1 receptor antibodies in the nerve stump significantly decreased in the 6-mm nerve conduit group. In the rat sciatic nerve amputation model, nerve capping treatment with a bioabsorbable nerve conduit provided relief from neuroma-induced neuropathic pain and prevented perineural scar formation and neuroinflammation around the nerve stump. The appropriate nerve conduit length was determined to be more than 4 times the diameter of the original nerve.

ESTUDO COMPARATIVO DA TÉCNICA DE REPARO DO NERVO ISQUIÁTICO DE RATOS WISTAR COM E SEM O USO DE INVÓLUCRO VENOSO

Abstract Background: Considering the quality of motor function, the authors compared different peripheral nerve repair techniques with the end-to-end neurorrhaphy technique associated with the venous wrap. As previously described by other authors, the vein wrapping technique has shown promising results regarding the reduction of nerve fiber dispersion, perineural scar and neuroma formation. However, data regarding motor recovery were not clear yet. Therefore, the aim of this study is to evaluate the motor recovery of the neurorraphy with vein wrapping. Methods: This article is an experimental study with randomized control trials. We used a rat sciatic nerve injury model in which we completely transected and repaired the right sciatic nerve. Therefore, 4 groups were created: control (C), end-to-end neurorrhaphy (N), vein tube (V) and the group of end-to-end neurorrhaphy associated with vein wrapping (NV). In the postoperative period, the specimens had motor function assessed by the Sciatic Function Index (SFI) at the 4th, 8th and 12th week. Results: Considering the motor function of the groups N and NV, these had showed a higher SFI score in relation to group C and V (p = 0.00000). Comparing N with NV both groups were identical, in other words, significant differences were not found (p=0,00631). Conclusions: Considering statistical data, groups N and NV were strictly equal. Therefore, the techniques of isolated end-to-end neurorrhapy or associated with the vein wrapping were similar in terms of motor function recovery and they may be used interchangeably. Keywords - Neurorrhaphy; Venous Sheath; Peripheral Nerve Injuries

Effect of chitosan combined with hyaluronate on promoting the recovery of postoperative facial nerve regeneration and function in rabbits.

To determine better solutions for postoperative nerve functional recovery, the effects of chitosan and hyaluronate on perineural scar formation and neural function recovery were investigated in 40 rabbits. Rabbits were randomized into 4 groups: A (chitosan), B (chitosan + hyaluronate), C (hyaluronate) and D (control). The rabbits underwent the same parotidectomy surgery, but different materials were used to cover the operated nerves. By evaluating specific indicators, including vibrissae motion tests, neural electrophysiological examinations and extraneural examinations, it was revealed that the amplitude of vibrissae motion of all groups had increased 6 weeks after surgery. The recovery of Group B was superior compared with all other groups at 4 and 12 weeks post-surgery; however no significant differences were detected. Group B exhibited a great number of nerve fibers, thicker myelin sheath and greater nerve conduction velocity. In summary, the use of a chitosan conduit combined with sodium hyaluronate gel may prevent perineural scar formation in facial nerves and promote nerve functional recovery.

Effects of hyaluronic acid and tacrolimus on the prevention of perineural scar formation and on nerve regeneration after sciatic nerve repair in a rabbit model

Scar formation after injured peripheral nerve repair is a significant clinical problem because it prevents nerve regeneration. The aim of this study was to investigate and compare the effects of hyaluronic acid (HA) and tacrolimus (FK506) on peripheral nerve regeneration in rabbits after the drugs were topically applied at the site of nerve repair. Thirty adult male European rabbits (Oryctolagus cuniculus), ranging in weight from 2.5 to 3kg, were randomly assigned to three groups: the HA and FK506 groups comprised the experimental groups, while the saline group served as the control. At week 12, macroscopic and microscopic evaluations were performed and analyzed. In general, the macroscopic evaluations (skin and muscle fascia closure and nerve adherence), microscopic evaluations (cellular components, scar tissue formation index, and histomorphological organization), and measurements of nerve diameter and gastrocnemius muscle wet weight demonstrated the positive effects of topical application of these pharmacological agents (HA and FK506); HA and FK506 prevented scar formation and enhanced nerve regeneration. No significant differences in the parameters described above were observed between the HA and FK506 groups (P>0.05). However, significant differences were observed between both the HA and FK506 groups and the saline group (P<0.05). Based on our findings, topical application of HA and FK506 exhibits equally positive effects, preventing perineural scar formation and enhancing nerve regeneration after peripheral nerve repair.

Efficacy of anti-adhesion gel of carboxymethylcellulose with polyethylene oxide on peripheral nerve: Experimental results on a mouse model

Perineural scar formation is responsible for pain and loss of function after surgical procedures. Neurolysis and application of anti-adhesion gels are required to restore a gliding surface. We tested a carboxymethylcellulose (CMC) and polyethylene oxide (PEO) gel on mouse sciatic nerve to describe its safety and efficacy. Adult mice underwent a surgical procedure in which we burned the muscular bed of the sciatic nerve bilaterally (Burned group) and applied anti-adhesion gel to 1 of the nerves (Burned+gel group). After 3 weeks, we studied scar tissue by biomechanical and histological evaluation. Both histological and biomechanical analysis showed that the gel reduced perineural scarring. The difference between the Burned and Burned+gel groups was statistically significant. CMC-PEO gel can reduce perineural scar tissue. In histological section, scar tissue was present in both groups, but in the Burned+gel group a gliding surface was identified between scar and nerve.

A simple and reliable method to perform biomechanical evaluation of postoperative nerve adhesions.

Perineural fibrotic adhesions are among the major complications of peripheral nerve surgery. While different experimental models have been used for the pre-clinical testing of anti-adherential strategies, the methods used so far to induce scar tissue appear to be poorly standardized and reproducible. Thirty adult mice were used. Two methods were tested: the first one is based on burning the perineural muscular bed with a diathermocoagulator, while the second is based on direct scratching of the nerve surface with a cotton swab. After 3 weeks, the fibrotic reaction was assessed by measuring the peak pull out force of the nerve from muscular bed by means of a new tool specifically devised for biomechanical assessment of scar tissue formation. Moreover, histological analysis with specific collagen stain was also carried out. Both methods produced fibrotic reaction. Statistical analysis of biomechanical data showed a significant difference between burning and scratching group compared to the control sham operated group. No significant differences were detected between burning and scratching group. Histological analysis showed the presence of perineural scar tissue in both groups, though with a different distribution pattern. This protocol is easier to perform. The tool used for biomechanical evaluation is reliable and cheap. Both methods for perineural scar formation are effective and simple. They represent reproducible models for the study of the anti-adherential strategies. Yet, biomechanical testing with the device that we have developed proved to be a reliable and simple method for the quantitative assessment of the degree of perineural adhesion formation.

Does the addition of a nerve wrap to a motor nerve repair affect motor outcomes?

The purpose of this study was to evaluate the effect of wrapping bioabsorbable nerve conduit around primary suture repair on motor nerve regeneration in a rat model. Forty rats were randomly divided into two experimental groups according to the type of repair of the rat sciatic nerve: group I had primary suture repair; group II had primary suture repair and bioabsorbable collagen nerve conduit (NeuraGen® 1.5 mm, Integra LifeSciences Corp., Plainsboro, NJ) wrapped around the repair. At 12 weeks, no significant differences in the percentage of recovery between the two groups were observed with respect to compound muscle action potentials, isometric muscle force, and muscle weight (P = 0.816, P = 0.698, P = 0.861, respectively). Histomorphometric analysis as compared to the non-operative sites was also not significantly different between the two groups in terms of number of myelinated axons, myelinated fiber area, and nerve fiber density (P = 0.368, P = 0.968, P = 0.071, respectively). Perineural scar tissue formation was greater in primary suture repair group (0.36 ± 0.15) than in primary repair plus conduit wrapping group (0.17 ± 0.08). This difference was statistically significant (P < 0.001). Wrapping bioabsorbable nerve conduit around primary nerve repair can decrease perineural scar tissue formation. Although the scar-decreasing effect of bioabsorbable nerve wrap does not translate into better motor nerve recovery in this study, it might have an effect on the functional outcome in humans where scar formation is much more evident than in rats.

Revision Decompression and Collagen Nerve Wrap for Recurrent and Persistent Compression Neuropathies of the Upper Extremity

Recurrent or persistent compression neuropathies of the upper extremity, including carpal and cubital tunnel syndrome, present a difficult treatment challenge to the hand or peripheral nerve surgeon. Collagen conduits have been used successfully for decades in nerve injury repair, but have not been studied in the treatment of compression neuropathy. Patients with recurrent or persistent compression neuropathies treated with a repeat decompression and collagen wrap from a 5-year period were retrieved from the Computerized Patient Record System database and 15 patient records were identified. A systematic review was performed for all articles from 1946 to 2012 on secondary carpal and cubital tunnel syndrome. The mean age of the 15 patients treated was 63.3 years and ranged from 35 to 86 years. The patients with revision carpal tunnel decompression had an 89% subjective response rate, whereas those with revision cubital tunnel decompression had an 83% resolution or improvement of symptoms. Visual analog scale decreased from a preoperative mean 2.47 to 0.47 postoperatively and the mean number of opiate medications decreased from 0.67 to 0.40. We identified 32 papers using various treatment strategies for recurrent carpal tunnel syndrome with success rates ranging from 53% to 100%. We identified 18 papers on recurrent cubital tunnel syndrome, with success rates ranging from 33% to 100%, with a weighted success of 78.1% overall but 71.7% in the submuscular transposition group. Here we report on the novel technique of using a collagen matrix wrap in recurrent compression neuropathies with good success. The collagen wrap allows nerve gliding, protection from perineural scar formation, and a favorable microenvironment. Submuscular transposition seems to be no better than other methods of decompression for recurrent cubital tunnel syndrome in contrary to traditional teaching.

Comparison and evaluation of current animal models for perineural scar formation in rat.

Objective (s): Scar formation in injured peripheral nerve bed causes several consequences which impede the process of nerve regeneration. Several animal models are used for scar induction in preclinical studies which target prevention and/or suppression of perineural scar. This study evaluates the translational capacity of four of physical injury models to induce scar formation around the sciatic nerve of rat: laceration, crush, mince and burn. Functional (Toe out angle), macroscopic, and microscopic evaluations were performed weekly for four weeks and correlation of findings were analyzed. While macroscopic and microscopic findings suggested a well-developed and adhesive fibrosis surrounding the sciatic nerve, functional assessment did not reveal any significant difference between control and experimental groups (P>0.05). Our study suggests that none of the applied animal models reproduce all essential features of clinical perineural scar formation. Therefore, more studies are needed to develop optimal animal models for translating preclinical investigations.

Investigation of the dose-dependency of citicoline effects on nerve regeneration and functional recovery in a rat model of sciatic nerve injury

The aim of this study was to investigate the dose dependence of citicoline's previously-reported effects on recovery of peripheral nerve injury. Right sciatic nerves of sixty adult female Wistar Albino rats were incised and primary anastomosis was performed. Rats were then divided into four groups: Control group received 2 ml of saline intraperitoneally, while rats in C-300, C-600 and C-900 groups received 300 μmol/kg, 600 μmol/kg and 900 μmol/kg citicoline dissolved in 2 ml saline, respectively. Rats were tested for sciatic functional index (SFI) on the 4th, 8th and 12th weeks and electrophysiological recordings were obtained on the 12th week. Rats were then sacrificed to investigate nerve adhesions and perform histomorphological examinations. Our results showed that rats in C-600 and C-900 groups had significantly lesser neural adhesion and greater SFI and electrophysiological score than those in the Control and C-300 groups (p < 0.05). Mean density and total number of functionally myelinated axons were significantly increased in C-900 group, while perineural scar tissue formation was reduced in all citicoline-treated groups. We conclude that citicoline exhibits dose-dependent effects on axonal regeneration and recovery without scar formation in a rat model of peripheral nerve incision and primary anastomosis.

Effect of Hyaluronic Acid-Carboxymethylcellulose Solution on Perineural Scar Formation after Sciatic Nerve Repair in Rats

BackgroundScar tissue formation is the major cause of failure in peripheral nerve surgery. Use of a hyaluronic acid-carboxymethylcellulose (HA-CMC) membrane (Seprafilm) as a solid anti-adhesion barrier agent is one of the therapeutic approaches to reduce postoperative scar tissue formation. However, a solid membrane may not be suitable for repair of a weak peripheral nerve site. This study examined the effect of HA-CMC solution on perineural scar formation after peripheral nerve repair in rats.MethodsThe sciatic nerves of 40 rats were transected and then immediately repaired using 10-0 nylon. The nerves were divided randomly into two groups. Saline and HA-CMC solution were applied topically to the nerve repair sites in the control and experimental groups, respectively. Reoperation was performed at 3, 6, 9, and 12 weeks to assess scar tissue formation. The assessment included the quality of wound healing, presence of perinueral adhesion, cellular components of the scar tissue, thickness of the scar tissue and histomorphological organization of the repair site.ResultsTopical application of the HA-CMC solution significantly decreased the macroscopic nerve adherence score and the numbers of the cellular components such as fibroblasts and inflammatory cells (p < 0.05, Mann-Whitney U-test). The scar tissue formation index was significantly lower in the experimental group at 12 weeks than that in the control group (p < 0.05, Mann-Whitney U-test). The grading scores of the histomorphological axonal organization at the repair site were significantly higher in the experimental group than those in the control group at 12 weeks (p < 0.05, Mann-Whitney U-test). No evidence of wound dehiscence or inflammatory reactions against the HA-CMC solution was noted.ConclusionsTopical application of a HA-CMC solution is effective in reducing the perineural scar formation and adhesion after sciatic nerve repair in rats, and is effective in promoting peripheral nerve regeneration at the repair site.

Collagen nerve protector in rat sciatic nerve repair: A morphometric and histological analysis

Peripheral nerve repair is often complicated by fibroblastic scar formation, nerve dysfunction, and traumatic neuroma formation. Use of bio-absorbable protective wraps may improve outcomes of these repairs. This study histologically compared the incidence of neuroma formation, connective tissue proliferation, and axonal regrowth in transected rat sciatic nerves repaired with and without tubular collagen nerve sleeves. Twenty Sprague-Dawley rats underwent unilateral sharp sciatic nerve transection and microscopic nerve repair with four epineural sutures and were randomly treated with or without an encircling collagen nerve sleeve. Normal nerves from the contralateral sciatic nerve were also examined. At sacrifice three months later, the nerves were evaluated for traumatic neuroma formation, perineural scar formation, and morphometric analysis. Histological examination of normal and repaired nerves by a neuropathologist demonstrated healing, minimal Wallerian degeneration and no traumatic neuroma formation. Distal section analysis (nine nonwrapped, 10 wrapped), revealed no significant differences in total fascicular area, myelinated fibers per nerve, fiber density, myelin area per nerve, myelinated fiber diameter, axon diameter, myelin thickness, or G-ratio. Significantly greater (P = 0.005) inner epineural connective tissue formation was observed in nonwrapped nerves (0.62 mm(2) +/- 0.2) versus wrapped nerves (0.35 mm(2) +/- 0.16). The ratio of connective tissue to fascicular area was larger in nonwrapped (1.08 +/- 0.26) versus wrapped nerves (0.63 +/- 0.22) (P < 0.001). This study demonstrated decreased inner epineural connective tissue formation with use of a collagen nerve wrap during primary repair of peripheral nerve transection in a rat sciatic nerve model.

Submuscular Versus Subcutaneous Anterior Ulnar Nerve Transposition: A Rat Histologic Study

The 2 most common methods of ulnar nerve anterior transposition are submuscular and subcutaneous. Controversy exists as to which technique yields superior results. The purpose of this study was to examine the histologic differences between the 2 methods in a rat model. Twenty forelimbs in 10 adult Sprague-Dawley rats had bilateral ulnar nerve transpositions; one side with the submuscular method, and the other side with the subcutaneous method. Animals were killed 6 weeks after the index surgery and the forelimbs were examined for histologic evidence of the health of the axons and perineural scar formation. Nerve health was assessed using a 4-part classification in which 4 = normal nerve, 3 = abnormal axons in one-third cross-sectional area (CSA), 2 = abnormal axons in two-thirds CSA, and 1 = abnormal axons in 100% CSA. Perineural scar formation was assessed using a 3-part classification in which 3 = scar completely encasing nerve, 2 = scar formation partially surrounding nerve, and 1 = no scar. The submuscular method displayed healthier ulnar nerve axons. In addition, the submuscular method displayed less perineural scar tissue. On this basis of this rat model, the submuscular method of ulnar nerve anterior transposition displayed histologically healthier axons and less perineural scar tissue when compared to the subcutaneous method.

Comparative Study of Scar Formation at the Site of Sciatic Nerve Repair in Rats

Purpose : To investigate the effectiveness and to compare the degree of axonal regeneration with the control after the topical application of dexamethasone, hyaluronic acid and amniotic fluid at the repair site of the peripheral nerve. Materials and Methods : The left sciatic nerves of 40 adult Sprague-Dawley rats were transected and neurorrhaphy was performed. The nerves were divided into four groups according to thesolution applied around the repair site: control group (group 1), 0.3 ml normal saline: experimental groups, 0.3 ml dexamethasone (group 2), 0.3 ml hyaluronic acid (group 3), and 0.3 ml amniotic fluid (group 4). The thickness of the perineural scar tissue, the count of the myelinated nerve fiber and axonal regeneration on the repair site were evaluated electromyographically and histologically 4 and 12 weeks after surgery. Results : The peak amplitude of the compound motor action potential was observed in group 2, at postoperative 4 weeks and group 3 at postoperative 12 weeks. The increase in the number of myelinated nerve fibers was most prominently in group 3 at 4 and 12 weeks after surgery. The degree of perineural scarring was lowest in group 2 at postoperative 4 weeks and in group 3 at postoperative 12 weeks. Conclusion : A single dose topical application of Dexamethasone, HA and Amniotic fluid is more effective in preventing perineural scar formation as well as in facilitating the nerve regeneration process in a rat hind-limb model than using saline.

Lumbar microdiscectomy with and without prophylaxis of perineural scar formation using ADCON-L barrier gel – 2-year results

A retrospective study investigated the advantages of the intraoperative application of the anti-adhesion barrier gel ADCON-L after lumbar microdiscectomy. For the study 92 patients were recruited. Following the operation 46 patients (study group) received ADCON-L application. In another 46 patients (control group), wounds were closed without ADCON-L application. Median follow-up was 32 (26–33) months in the study group and 37 (32–41) months in the control group postoperation. All patients were examined clinically and spinal MRIs carried out on 12 randomly selected patients in each group. According to the score of the Low Back Pain Committee of the Japanese Orthopedic Association, no significant clinical difference could be established between the two groups. Subjective evaluation of operation results (score according to Weber) was not significant. Peridural scarring in the postoperative MRI of 24 patients did not differ significantly. A significant effect on clinical results after ADCON-L application could not be found.

The effects of free fat grafts on the stiffness of the rat sciatic nerve and perineural scar.

We developed a new quantitative rat sciatic nerve model to test whether free fat grafts can reduce postoperative perineural scar formation. Epineurectomies of sciatic nerves were performed to create scar. The force required to distract the nerve a unit distance was measured after surgery to determine the time of maximal scar formation. Nerve stiffness normalized for rat weight was statistically greater at 2 months after the initial dissection (0.097+/-0.009 g/mm/g rat weight; n = 10 limbs) than rat limbs that had not undergone a previous dissection (0.075+/-0.012 g/mm/g rat weight). Perineural scar thickness was thicker at 2 months than the perineural tissue in preoperative controls. Free fat grafts decreased nerve stiffness at 2 months (0.078+/-0.012 g/mm/g rat weight) in comparison to the contralateral surgical control limb without a fat graft (0.094+/-0.014 g/mm/g rat weight). Free fat grafts reduced the strength of postoperative perineural scar in this surgical model; however, they were associated with an unexpected finding of substantial postoperative neuropathy.

Entrapment radiculopathy: Hypothesis that explains spinal nerve root disorders after spontaneous resorption of lumbar disc herniation

This paper presents ten cases of lumbar spinal nerve root disorder differing from ordinary lumbar disc herniation (LDH) in pathology. The lumbar spinal nerve roots of the ten patients were entrapped or anchored to the posterior longitudinal ligament (PLL), as in entrapment peripheral neuropathy, causing symptoms of radiculopathy similar to LDH. Regression or complete resorption of LDH has been frequently reported. The pathology of perineural conditions after spontaneous resorption, however, has not been expensively studied. We compared disc degeneration in these patients with degeneration in patients with ordinary LDH, based on magnetic resonance imaging (MRI). We also compared the clinical courses in the two groups. The affected discs of 106 patients with low back pain and sciatica, treated operatively for LDH from July 1989 to October 1994 were studied and graded by MRI to assess disc degeneration. Of these 106 patients, 10 exhibited lumbar spinal nerve adhesion to the PLL (entrapment radiculopathy) without herniation mass on myelogram, computed tomography (CT)-myelogram, and MRI. The disc degeneration in the 10 patients showing nerve root entrapment corresponded to that in the 96 patients with LDH. All ten patients had a similar clinical history of recurrent sciatica and low back pain after remission of the first onset, and good results were obtained after neurolysis with free fat grafting, performed to protect against perineural scar formation or adhesions. One patient was follow-up from onset to recurrence by MRI. The pathology “entrapment radiculopathy” may be present in some patients with LDH after spontaneous resorption. Careful follow-up is necessary, even when spontaneous resorption of LDH is recognized by MRI or CT.

Percutaneous Lateral Discectomy of the Lumbar Spine

The description in a French journal in 1775 of cerclage wiring of a humerus has been widely accepted as the first recorded case of internal fixation of a fresh fracture. Retranslation reveals that the operation was not in fact performed, although the subject was of surgical interest at that time.