Nerve regeneration following primary repair

Summary In nine selected cases a primary nerve repair was done. In all these patients a special suture was used. Applying clinical and neurophysiological tests, regeneration of the motor and sensory nerve fibres was followed for two years.A remarkable difference in growth rates of sensory and motor nerve fibres was observed. The average rate of growth of sensory nerve fibres was 5 mm a day, and of motor nerve fibres it was 1.7 mm a day. At the end of a two years' interval after operation, good recovery from the initial muscular atrophy was observed in all but two cases. Function of previously denervated muscles was nearly normal. Discrimination of points 4–10 mm apart was possible. Normal terminal conduction times along motor nerve fibres were found in five eases. Slightly prolonged times were found in four. Calculated conduction velocities in sensory nerve fibres were half to three quarters of normal times.All patients resumed their previous occupations.     

A preliminary investigation of the reinnervation and return of sensory function in burn patients treated with INTEGRA®

Background

Loss of sensory function in scar after burn is common, although the basis for this loss is not clear. Additionally, little is known about the effects of different treatment modalities on sensory function and neuroanatomical outcomes in burn patients. Here, we investigated the effects of the use of the INTEGRA^® dermal scaffold on neuroanatomy and sensory function in acute burn patients.

Hypothesis and objectives

We hypothesized that the use of artificial dermal templates would inhibit or reduce reinnervation after excision, since regrowth of nerves requires complex molecular interactions. Therefore the primary objective of this study was to identify whether there is regrowth of nerve fibres in the INTEGRA^® dermal scaffold. The secondary objective was to identify whether the INTEGRA^® dermal scaffold reduced nerve regrowth or limited sensory function outcomes in acute burn patients.

Methods

Five patients treated with INTEGRA^®, cultured epithelial autograft spray (prepared using ReCell^® (CEA)) and split skin graft (SSG) were assessed for sensory function in scar and uninjured contralateral control skin. Neuroanatomy of scar and control sites was assessed using immunohistochemistry for PGP9.5, CGRP and substance P neuronal markers. Nerve density and sensory function was also assessed in a comparative group (n = 8) treated with CEA and SSG only.

Results

Neuroanatomy was not significantly different in the INTEGRA^® patients when compared to the CEA/SSG group only. The patients treated with INTEGRA^® had worse sensory function than those with CEA/SSG only.

Conclusions

Peripheral nerves do reinnervate the INTEGRA^® dermal scaffold. There is no statistically significant reduction in reinnervation observed when compared to a control group. It is possible that the use of artificial dermal constructs, while permissive for nerve regrowth, limit functionality when compared to nerves that regrow through dermal tissue. Further research to understand the causes of this, and into enhancing reinnervation in dermal scaffolds may improve sensory outcome in the most severely burned patients.     

周围神经损伤感觉终器退变与重建实验研究

目的：通过观察灵长类动物指神经切断后感觉终器的退变和不同时间修复神经后感觉终器的重建过程，以证实修复晚期周围神经损伤恢复感觉功能的临床价值。方法：检测方法采用感觉神经传导速度、神经纤维镀银染色、非特异胆碱酯酶染色、感觉终器超微结构观察等。结果经计算机图象分析和统计学分析。结果：Ｍｅｉｓｓｎｅｒ小体失神经支配３０周基本退变消失。在小体消失前修复神经，再生神经纤维可以与残留的小体重建连接。Ｍｅｉｓｓｎｅｒ小体消失以后不能再生。再生神经纤维长入真皮乳头，以游离末梢的形式恢复部分功能。ｐａｃｉｎｉａｎ小体退变缓慢，修复神经后可以恢复基本结构。结论：作者认为修复晚期周围神经损伤重建感觉功能有重要的价值。     

SENSORY RECOVERY AFTER HAND REIMPLANTATION: A CLINICAL,MORPHOLOGICAL, AND NEUROPHYSIOLOGICAL STUDY IN HUMANS

Despite fairly good return of motor function, patients who have amputated hands reimplanted demonstrate poor sensory recovery and severe cold intolerance, two variables that are difficult to quantify reliably. In this study we wanted to find out if there is a correlation between morphological findings of sensory and sympathetic reinnervation and clinical and neurophysiological variables. Skin was biopsied from the reimplanted and corresponding area in the normal hands of eight patients who had sustained a hand amputation and subsequent reimplantation. The sections were immunostained using markers for both sensory and sympathetic nerve fibres. Comparison between the reimplanted and normal sides in each individual showed a mean loss of sensory immunoreactive nerve fibres of 30%, and for sympathetic immunoreactivity the loss was 60%. There was measurable two-point discrimination in the injured hand only in patients below the age of 40 years, corresponding to the better recovery of mechanical thresholds evaluated neurophysiologically for this age group. These results confirm the extensive loss of sensory nerve fibres after nerve injury, probably correlated to loss of sensory neurons. We have also shown that it is possible to correlate the results of clinical and neurophysiological evaluation with morphological results of skin reinnervation specific to the repaired nerve, and so improve the possibility for the quantification of sensory recovery.     

Sensory recovery after hand reimplantation: a clinical, morphological, and neurophysiological study in humans.

Despite fairly good return of motor function, patients who have amputated hands reimplanted demonstrate poor sensory recovery and severe cold intolerance, two variables that are difficult to quantify reliably. In this study we wanted to find out if there is a correlation between morphological findings of sensory and sympathetic reinnervation and clinical and neurophysiological variables. Skin was biopsied from the reimplanted and corresponding area in the normal hands of eight patients who had sustained a hand amputation and subsequent reimplantation. The sections were immunostained using markers for both sensory and sympathetic nerve fibres. Comparison between the reimplanted and normal sides in each individual showed a mean loss of sensory immunoreactive nerve fibres of 30%, and for sympathetic immunoreactivity the loss was 60%. There was measurable two-point discrimination in the injured hand only in patients below the age of 40 years, corresponding to the better recovery of mechanical thresholds evaluated neurophysiologically for this age group. These results confirm the extensive loss of sensory nerve fibres after nerve injury, probably correlated to loss of sensory neurons. We have also shown that it is possible to correlate the results of clinical and neurophysiological evaluation with morphological results of skin reinnervation specific to the repaired nerve, and so improve the possibility for the quantification of sensory recovery.     

Up-regulation of α1-adrenoceptors in burn and keloid scars

Stimulation of α₁-adrenoceptors evokes inflammatory cytokine production, boosts neurogenic inflammation and pain, and influences cellular migration and proliferation. Hence, these receptors may play a role both in normal and abnormal wound healing. To investigate this, the distribution of α₁-adrenoceptors in skin biopsies of burn scars (N = 17), keloid scars (N = 12) and unscarred skin (N = 17) was assessed using immunohistochemistry. Staining intensity was greater on vascular smooth muscle in burn scars than in unscarred tissue, consistent with heightened expression of α₁-adrenoceptors. In addition, expression of α₁-adrenoceptors was greater on dermal nerve fibres, blood vessels and fibroblasts in keloid scars than in either burn scars or unscarred skin. These findings suggest that increased vascular expression of α₁-adrenoceptors could alter circulatory dynamics both in burn and keloid scars. In addition, the augmented expression of α₁-adrenoceptors in keloid tissue may contribute to processes that produce or maintain keloid scars, and might be a source of the uncomfortable sensations often associated with these scars.     

P2X3-immunoreactive nerve fibres in neurogenic detrusor overactivity and the effect of intravesical resiniferatoxin

OBJECTIVES: The ATP-gated purinergic receptor P2X3 is expressed by small diameter sensory neurons and has been identified in normal and neurogenic human bladder suburothelial fibres. Animal models have shown that ATP is released by the urothelium during bladder distension, suggesting a mechanosensory role for P2X3 receptors in normal bladder function. Successful treatment of spinal neurogenic detrusor overactivity (NDO) with intravesical resiniferatoxin (RTX), which partly acts on suburothelial C fibres, provides evidence for the emergence of a C fibre-mediated spinal reflex. The aim of this study was to investigate the possible role of P2X3-positive innervation in this pathological voiding reflex by comparing suburothelial P2X3 immunoreactivity of controls and in patients with NDO before and after intravesical RTX. METHODS: Bladder biopsies were obtained from 8 controls and 20 patients with refractory NDO enrolled in a trial of intravesical RTX. P2X3 nerve fibre density and intensity were studied in the specimens by immunohistochemistry. RESULTS: P2X3-IR nerve fibres were significantly increased in patients with NDO compared to controls (p=0.014). Thirteen patients had pre- and post-RTX biopsies available for immunohistochemistry; 5 of them responded clinically and 8 were non-responders. In the 5 patients who responded to RTX, there was a significant decrease in P2X3-positive fibres (p=0.032), whereas in non-responders, P2X3-IR nerve fibre density did not change significantly. CONCLUSIONS: In patients with NDO, the numbers of P2X3-IR nerve fibres were increased in the suburothelium. There was a significant decrease in P2X3 immunoreactivity in responders to RTX, indicating a potential pathophysiological role for the P2X3 expressing fibres.     

The effect of surgical denervation on prevention of excessive dermal scarring: A study on rabbit ear hypertrophic scar model

Background

Previous reports have suggested that the extent of wound contraction, epithelisation and total healing time were influenced by denervation of tissues. In this article, we studied for the first time the effect of sensory denervation on prevention of excessive dermal scarring.

Materials and Methods

Sixteen New Zealand white rabbits were used. Denervation of the right ears was performed by surgical excision of two main sensory nerves. Dissections were also performed on left ears without any nerve excision for the control group. After 14 days of follow-up and confirmation of tissue denervation, an excessive dermal scarring model as defined by Morris et al. was made by surgery on both ears. Twenty-eight days after making the wounds, the tissues were extirpated for analyses. The scars were evaluated by the scar elevation index (SEI), epithelisation time and inflammatory cell count.

Results

The SEI of the denervated side scars was significantly lower than that of the non-denervated side. The rate and timing of total epithelisation and inflammatory cell count between groups yielded no difference.

Conclusions

In this study, the surgical denervation skin reduced scarring. It was suggested that understanding the exact role of sensory nerves and neural mediators in excessive dermal scarring is necessary for the prevention and treatment of scarring.     

P2X receptors in sensory neurones

P2X receptors are a family of ligand-gated ion channels responsive to ATP. Seven subtypes have been identified which form homo-multimeric or hetero-multimeric pores. P2X3 receptors are selectively expressed predominantly on small-diameter nociceptive sensory neurones in the dorsal root, trigeminal and nodose ganglia, particularly the non- peptidergic subpopulations labelled with the lectin IB4. P2X2/3 labelling is also present in inner lamina II of the spinal cord and in sensory nerve projections to skin and viscera, but few receptors are present in skeletal muscle. P2X3 receptors are down-regulated after peripheral nerve injury and their expression can be regulated by glial cell-derived neurotrophic factor. P2X receptor activation of sensory neurones has been demonstrated in in vivo pain models, including the rat hindpaw and knee-joint preparations, as well as in inflammatory models. P2X4 and/or P2X6 receptors in the CNS also seem to be involved in pain pathways. Non-nociceptive P2 receptors on sensory nerves are present in muscle and on sensory endings in the heart and lung that initiate reflex activity involving vagal afferent and efferent nerve fibres. The sources of ATP involved in nociception and non-nociceptive sensory nerve stimulation are discussed as well as a novel hypothesis about purinergic mechanosensory transduction.      

Long term sensory function after minor partial thickness burn: A pilot study to determine if recovery is complete or incomplete

BackgroundAcute burn damages skin architecture, including nerve endings, altering sensation and influencing recovery of quality of life and participation. It is established that sensation is reduced in scars after deep burn. However, it is unclear if sensory deficits exist in mild scars. The aim of this trial was to determine if sensory deficits persist in mature scars after minor partial thickness burn.MethodsThis observational pilot involved 30 patients with ‘good quality’ scars (defined as VSS ≤5 at ≥6 months post-burn). Sensory function was compared in scars and site matched uninjured skin using von Frey filaments and two-point discrimination (2-PD). Multivariable regression was used to predict the influence of burn and confounders on sensory outcomes.ResultsBoth pressure and 2-PD distance were significantly greater in scar compared to uninjured sites, indicating reduced sensory function. For von Frey filaments, the median was 3.84 (IQR = 1) in scars and 3.22 (IQR = 1) for uninjured (p = 0.001). For 2-PD, the median was 3.9 cm (IQR = 1.8) for scars and 2.6 cm (IQR = 1.6) for control sites (p = 0.001).ConclusionMeasureable sensory deficits persist in mature, good quality burn scars. These deficits may influence long-term recovery after minor partial thickness burn.     

Sensory hypoinnervation in club foot

We have compared the density of nerve fibres in the synovium in club foot with that of specimens obtained from the synovium of the hip at operations for developmental dysplasia. The study focused on the sensory neuropeptides substance P; calcitonin gene-related peptide; protein gene product 9.5, a general marker for mature peripheral nerve fibres; and growth associated protein 43, a neuronal marker for new or regenerating nerve fibres. In order to establish whether there might be any inherent difference we analysed the density of calcitonin gene-related peptide-positive nerve fibres in the hip and ankle joints in young rats. Semi-quantitative analysis showed a significant reduction in the number of sensory and mature nerve fibres in the synovium in club foot compared with the control hips. Calcitonin gene-related peptide (CGRP) positive fibres were reduced by 28%, substance P-positive fibres by 36% and protein gene product 9.5-positive fibres by 52% in club foot. The growth associated protein 43-positive fibres also seemed to be less in six samples of club foot. No difference in the density of CGRP-positive nerve fibres was observed in the synovium between ankle and hip joints in rats. The lack of sensory input may be responsible for the fibrosis and soft-tissue contractures associated with idiopathic club foot.     

Clinical effectiveness of dermal substitution in burns by topical negative pressure: A multicenter randomized controlled trial

Previous research has shown clinical effectiveness of dermal substitution; however, in burn wounds, only limited effect has been shown. A problem in burn wounds is the reduced take of the autograft, when the substitute and graft are applied in one procedure. Recently, application of topical negative pressure (TNP) was shown to improve graft take. The aim of this study was to investigate if application of a dermal substitute in combination with TNP improves scar quality after burns. In a four‐armed multicenter randomized controlled trial, a split‐skin graft with or without a dermal substitute and with or without TNP was compared in patients with deep dermal or full‐thickness burns requiring skin transplantation. Graft take and rate of wound epithelialization were evaluated. Three and 12 months postoperatively, scar parameters were measured. The results of 86 patients showed that graft take and epithelialization did not reveal significant differences. Significantly fewer wounds in the TNP group showed postoperative contamination, compared to other groups. Highest elasticity was measured in scars treated with the substitute and TNP, which was significantly better compared to scars treated with the substitute alone. Concluding, this randomized controlled trial shows the effectiveness of dermal substitution combined with TNP in burns, based on extensive wound and scar measurements.     

Differentiation of superficial-partial vs. deep-partial thickness burn injuries in vivo by confocal-laser-scanning microscopy

Objective

The current determination of burn depth is based both on a visual and clinical assessment. Confocal-laser-scanning microscopy (CLSM) enables in vivo histomorphological images. We hypothesized that CLSM can differentiate superficial-partial vs. deep-partial thickness burns on a histomorphological level.

Methods

Thirty-eight burn wounds in 14 patients were clinically divided in three groups from superficial (group 1), superficial-partial (group 2) to deep-partial (group 3) thickness burns. CLSM was performed with the Vivascope1500 (Lucid Inc., Rochester, NY, USA) 24 h after burn. The following parameters were assessed: cell size of the granular-layer, thickness of the basal-layer, minimal thickness of the epidermis and number of perfused dermal papillae.

Results

Superficial burns resulted in a significant increase of the cell size of the granular-layer and a higher increase of the minimal thickness of the epidermis as in superficial-partial thickness burns. The granular-layer in partial thickness burns was destroyed. Superficial burns had an increased thickness of the basal-layer; in superficial-partial thickness burns the basal-layer was partly destroyed with complete destruction in deep-partial thickness burns. In superficial burns the perfused dermal papillae were increased significantly, while decreased in superficial-partial thickness, and completely destroyed in deep-partial thickness burns up to a depth of 350 μm.

Conclusions

In vivo confocal-laser-scanning microscopy can differentiate superficial-partial vs. deep-partial thickness burns on a histomorphological level.     

The sensory-motor bridge neurorraphy: an anatomic study of feasibility between sensory branch of the musculocutaneous nerve and deep branch of the radial nerve

Introduction: Restoring elbow flexion remains the first step in the management of total palsy of the brachial plexus. Non avulsed upper roots may be grafted on the musculocutaneous nerve. When this nerve is entirely grafted, some motor fibres regenerate within the sensory fibres quota. Aiming potential utilization of these lost motor fibres, we attempted suturing the sensory branch of the musculocutaneous nerve onto the deep branch of the radial nerve. The objective of our study was to assess the anatomic feasibility of such direct suturing of the terminal sensory branch of the musculocutaneous nerve onto the deep branch of the radial nerve. Methods: The study was carried out with 10 upper limbs from fresh cadavers. The sensory branch of the musculocutaneous muscle was dissected right to its division. The motor branch of the radial nerve was identified and dissected as proximally as possible into the radial nerve. Then, the distance separating the two nerves was measured so as to assess whether direct neurorraphy of the two branches was feasible. Results: The excessive distance between the two branches averaged 6 mm (1–13 mm). Thus, direct neurorraphy of the sensory branch of the musculocutaneous nerve and the deep branch of the radial nerve was possible. Conclusions: When the whole musculocutaneous nerve is grafted, some of its motor fibres are lost amongst the sensory fibres (cutaneous lateral antebrachial nerve). By suturing this sensory branch onto the deep branch of the radial nerve, “lost” fibres may be retrieved, resulting in restoration of digital extension. © 2011 Wiley‐Liss, Inc. Microsurgery, 2011.     

Improved method of dermatoplasty

For restoration of dermal integument on hands, feet, major joints, face and neck in 104 patients special device was used which provided creation of split dermal flaps of new types--with fenestrated gaping perforations or entire flaps with areas of various thickness which enabled to preserve islands of full thickness skin at donor's sites or superficial dermal layers. The thickness of the transplants made up 0.4-0.6 mm in adults and 0.25-0.5 mm in children. Perforated flaps were transplanted in 128 cases, the flaps of variable thickness--in 31. 151 operations (95.0%) resulted in complete recovering of the transplants, all wounds at donor's sites have closed spontaneously. Through 3-17 years after the operation the scars at perforations' sites looked hardly out of the ordinary, the areas of smaller thickness are unnoticeable, skin-grafts are soft and loading-proofed. The decrease in complications' rate and improvement of functional and aesthetic results of treatment after the application of the device were stated.     

下颌后小切口结合肿胀分离技术在髁突低位骨折内复位固定术中的应用

目的:探讨应用下颌后小切口及肿胀分离技术在髁突低位骨折切开复位内固定术中的应用效果。方法:对36例下颌骨髁突低位骨折患者采用下颌后小切口,术区皮下行肿胀液注射后紧贴皮下分离至咬肌表面,平行于面神经的方向钝性分离咬肌纤维,显露骨折部位,直视下行髁突骨折解剖复位内固定术。结果:术后通过临床及影像学检查随访,复位固定效果满意,无面神经损伤等严重并发症,切口瘢痕隐蔽。结论:下颌后小切口结合皮下肿胀分离技术处理髁突低位骨折具有安全、便捷、美观的优点,值得临床推广。     

Hyaluronic acid three‐dimensional scaffold for surgical revision of retracting scars: a human experimental study

An observational study was carried out at the Plastic and Reconstructive Surgery Unit of the University of Pavia – Salvatore Maugeri Research and Care Institute, Pavia, Italy, to assess the clinical and histological long‐term outcomes of autologous skin grafting of fresh surgical wounds following previous repair with a hyaluronic acid three‐dimensional scaffold (Hyalomatrix®). Eleven fresh wounds from surgical release of retracted scars were enrolled in this study. A stable skin‐like tissue cover was observed in all of the treated wounds in an average 1 month's time; at the end of this study, after an average of 12 months' time, all of the reconstructed areas were pliable and stable, although an average retraction rate of 51·62% was showed. Histological observation and immunohistochemical analysis displayed integration of the graft within the surrounding tissues. A regenerated dermis with an extracellular matrix rich in type I collagen and elastic fibres and with reduced type III collagen rate was observed. The epidermis and dermoepidermal junction featured a normal appearance with well‐structured dermal papillae, too. Although the histological features would suggest regeneration of a skin‐like tissue, with a good dermis and no signs of scarring, the clinical problem of secondary contracture is still unsolved.     

Nerve fibre and sensory end organ density in the epidermis and papillary dermis of the human hand.

Quantification of sensory recovery after peripheral nerve surgery is difficult and no accurate techniques are available at present. Quantification of reinnervated skin has been used experimentally, and in some clinical studies, but the lack of knowledge about the normal sensory distribution has been a problem. The purpose of this study was, therefore, to map the density of sensory end organs, nerve fibres and free nerve endings in the glabrous skin of the human hand. Skin biopsies were taken from patients undergoing acute and elective hand surgery. Nerve fibres were stained in the epidermis and papillary dermis and quantified in five sites on the palm of the hand, using protein gene product 9.5 immunoreactivity-a panneuronal marker. The finger tip skin was found to have more than twice the nerve fibre density in the papillary dermis than the skin of the palm, and the number of Meissner corpuscles in the finger tip was also higher than in the palm. We found a reduction in innervation density with increasing age in the dermis, however, that was not the case for the epidermis. The innervation of the epidermis showed high interindividual variability and unlike the papillary dermis did not display any pattern of distribution in the hand.     

Quantitative sensory and autonomic testing in male diabetic patients with erectile dysfunction

OBJECTIVE: To correlate abnormalities of nerve fibres in the lower limbs with erectile dysfunction in male diabetic patients, using a range of quantitative sensory and autonomic function tests. PATIENTS AND METHODS: The study included 68 male diabetic patients with symptomatic erectile dysfunction and 11 matched diabetics without erectile dysfunction; none had clinical evidence of peripheral vascular disease or psychological disorder. Patients were evaluated with a symptom questionnaire based on the Michigan Neuropathy Screening Instrument questionnaire and examined clinically. Sural and peroneal nerve-conduction studies, and quantitative sensory and autonomic tests (vibration, thermal, light-touch thresholds, sensory and autonomic cutaneous axon-reflexes) were used to detect nerve abnormalities in the lower limbs, which were correlated with erectile dysfunction. RESULTS: Symptoms of neuropathy were more common in the group with male erectile dysfunction (MED), but statistically significant only for neuropathic pain (53% MED, 18% nonMED, P<0.05, chi-square test) and gastroparesis (44% MED, 0% nonMED, P<0.05). Tests of unmyelinated afferents (warming perception and capsaicin-induced sensory axon-reflex vasodilatation) were most often abnormal, sometimes with no other abnormalities on tests or neurological examination. However, abnormality of warm perception was not significantly different between groups (81% MED, 70% nonMED), suggesting that it is a poorer discriminant than abnormal sensory axon-reflex vasodilatation (89% MED, 22% nonMED, P<0.001). The only other significant test difference was decreased sural nerve action potential (70% MED, 22% non-MED, P<0.01). CONCLUSIONS: There appeared to be preferential involvement of unmyelinated sensory fibres that mediate axon-reflex vasodilatation in the limbs of diabetic patients with erectile dysfunction. This test appears to be a helpful indicator of neurological involvement in erectile dysfunction, and may be used to monitor the effect of new treatments.     

Evaluation of sympathetic vasomotor fibres in carpal tunnel syndrome using continuous wave Doppler ultrasonography

Sympathetic vasomotor fibres carried by the median nerve and ulnar nerve innervate their respective sensory territories. The sympathetic vasomotor fibres of the median nerve were evaluated in patients with carpal tunnel syndrome and in healthy volunteers using continuous wave Doppler ultrasonography. The pulsatility index of the radialis indicis artery and the radial palmar digital artery of the little finger were measured at baseline and after stimulation. The maximal increase in the pulsatility index of each artery was measured. This was significantly lower for the radialis indicis artery in the CTS group than in the healthy controls. However, there was no significant difference in the maximal increase in pulsatility index of the radial palmar digital artery of the little finger between both groups. Sympathetic vasomotor fibres of the median nerve are affected in carpal tunnel syndrome. Continuous wave Doppler ultrasonography is easy to use and should be investigated further as a possible diagnostic tool for the confirmation of carpal tunnel syndrome.