Interposition of a pedicle fat flap significantly improves specificity of reinnervation and motor recovery after repair of transected nerves in adjacency in rats

Outcome of Stromal Vascular Fraction-Enriched Fat Grafting Compared to Intramuscular Transposition in Painful End-Neuromas of Superficial Radial Nerve: Preliminary Results

Introduction

The management of painful end-neuromas of the superficial branch of the radial nerve (SBRN) remains challenging due to high levels of pain relapse. The novel technique of stromal vascular fraction (SVF)-enriched fat grafting showed continuous pain relief, although failed to prove statistically significant. Besides acting as a mechanical barrier, SVF-enriched fat grafting might also affect the cellular level. The aim of this study was to compare clinical outcomes of SVF to the widely popular intramuscular transposition technique.

Patients and methods

In this cohort study, 10 consecutive patients treated for painful end-neuromas of the SBRN between 2010 and 2013 were analyzed retrospectively. Microsurgical resection of end-neuromas was performed in all patients. Five patients were treated with subsequent intramuscular transposition into the brachioradialis muscle and five patients received SVF-enriched fat grafting. Five different pain modalities and various predictors were compared pre- and up to 36 months post-operatively.

Results

In the transposition group, sustained pain reduction was not observed after an initial significant reduction 2 months’ post-surgery, resulting in pain relapse at 36 months and comparable to the preoperative assessment. In the graft group, some degree of pain reduction was observed at 2 months after the surgery and proved to be constant in the long-term outcome, although not statistically significant compared to preoperative levels.

Conclusion

Both SVF-enriched fat grafting and intramuscular transposition failed to prove statistical significant pain reduction in treating symptomatic neuromas of peripheral nerves.

Stromal Vascular Fraction-enriched Fat Grafting for the Treatment of Symptomatic End-neuromata

The purpose of this study was to methodically illustrate and highlight the crucial steps of stromal vascular fraction (SVF)-enriched fat grafting as a novel treatment of symptomatic end-neuromata of peripheral sensory nerves, and in this study, specifically of the superficial branch of the radial nerve (SBRN). Despite a multitude of existing treatments, persistent postoperative pain and common pain relapse are still very common, independent of the procedure assessed. The neuroma is microsurgically excised accordingly to standardized protocol. Instead of the relocation of the regenerating nerve stump in neighboring anatomical structures, such as muscle or bone, a fat graft is applied perifocally and acts as a mechanical barrier. In order to reduce the fat resorption rate and boost the regenerative potential of the graft, the highly concentrated SVF is integrated in the grafting. The SVF is isolated from subcutaneous fat by enzymatic and mechanic separation of the lipoaspirate by a specific commercial isolation system. The SVF-enriched fat graft provides both a mechanical barrier and various biological effects at the cellular level, including improving angiogenesis, inflammation, and fibrosis. Both mechanical and biologic effects help to reduce the disorganized axonal outgrowth of the nerve stump during nerve regeneration and hence prevent the recurrence of painful end-neuromata.

Scar Tissue Causing Saphenous Nerve Entrapment: Percutaneous Scar Release and Fat Grafting

Painful neuropathies can be caused by nerve compression or neuromas. Nerve compressions can arise from scar adhesions causing painful posttraumatic entrapment of nerve branches via fibrosis. The classical treatment methods include neurolysis and nerve transposition. In this case, we present the treatment of recurrent scar entrapment of the saphenous nerve with percutaneous neurolysis and lipofilling in a patient who had previously undergone an open neurolysis procedure. Resolution of the condition without any complications was noted during the 2-month clinical follow-up. Percutaneous neurolysis and lipofilling are shown to be safe and reproducible methods for the treatment of neuropathic compressive scars.

The novel treatment of SVF-enriched fat grafting for painful end-neuromas of superficial radial nerve

INTRODUCTION

None of the existing treatments in the management of painful end-neuromas of the superficial branch of the radial nerve (SBRN) has been proven superior due to high levels of pain relapse. Fat grafts enriched with the stromal vascular fraction (SVF) could act as a mechanic barrier with biological effects decreasing the resorption rate and boosting the graft's regenerative potential. This study describes the novel surgical treatment technique of SVF-enriched fat grafting.

PATIENTS AND METHODS

In this clinical study, five consecutive patients treated for painful end-neuromas of the SBRN between 2012 and 2013 were analyzed retrospectively. Microsurgical resection of end-neuromas followed by SVF-enriched fat grafting around the nerve stump was performed in all patients. Five different pain modalities and various predictors were compared pre- and up to 36 months postoperatively.

RESULTS

Pain reduction observed at 2 months after surgery was constant over time, though not statistically significant compared to preoperative levels. Spontaneous pain could be reduced from 1.6 ± 0.55 to 1.2 ± 1.1 (p = 0.414), spikes from 2.2 ± 1.3 to 1.4 ± 1.34 (p = 0.180), hyperaesthesia from 1.6 ± 1.14 to 1.2 ± 1.64 (p = 0.713), tap pain from 2.8 ± 0.45 to 1.8 ± 1.3 (p = 0.197) and motion pain from 2.8 ± 0.45 to 1.4 ± 1.34 (p = 0.066). An improvement in overall pain reduction could be observed from 2.2 ± 0.97 to 1.4 ± 1.26 3 years after the surgery (p = 0.104).

CONCLUSION

SVF-enriched fat grafting represents another alternative to numerous available treatments of painful end-neuromas of the SBRN. Our preliminary results could not show any significant difference in pain reduction following SVF-enriched fat grafting. Further larger trials are required in order to evaluate the therapeutic potential of SVF-enriched fat grafting.

Nerve regeneration techniques respecting the special characteristics of the inferior alveolar nerve

PURPOSE

The aim of this study was to examine the in situ regeneration of the inferior alveolar nerve (IAN) in its bony channel, using autologous tissue in combination with a recombinant human nerve growth factor (rhNGF).

MATERIALS AND METHODS

A total of 20 New Zealand rabbits were randomly divided into five groups. Following dissection of the IAN, the animals underwent reconstruction either with muscle tissue (groups 1 and 2) or with fat tissue (groups 3 and 4). In group 5 (control), the dissected nerve was resected and reconstructed by placement of the reversed autologous segment. After 2 and 4 weeks, 1 mL rhNGF was locally injected in groups 1 and 3. Nerve function was monitored by measuring the jaw-opening reflex using electromyography for a period of 24 weeks.

RESULTS

Regeneration of the nerve was achieved in all groups, but preoperative threshold values were not achieved. Comparing the experimental groups to the control, there was a significant difference in favor of the autologous nerve reconstruction. Differences between the experimental groups remained statistically not significant.

CONCLUSION

Regeneration of the IAN with autologous tissue is possible, but without achieving preoperative thresholds. Additional injection of a growth factor seems to improve the speed of regeneration for fat and muscle grafts.

The role of a barrier between two nerve fascicles in adjacency after transection and repair of a peripheral nerve trunk

Aberrant reinnervation of target organs caused by misdirected axonal growth at the repair site is a major reason for the poor functional outcome usually seen after peripheral nerve transection and repair. The following two studies investigate whether criss-crossing of regenerating rat sciatic nerve axons between tibial and peroneal nerve fascicles can be reduced by using a barrier at the coaption site. The left sciatic nerve was transected and repaired at mid-thigh as follows: epineural sutures (group A, A-II), fascicular repair of tibial and peroneal nerve fascicles (group B, B-II), fascicular repair of tibial and peroneal nerve fascicles separating the two fascicles with a pedicled fat flap (group C), Integra (group D) or non-vascularized autologous fascia (group C-II). In the control groups E and D-II, only the left tibial fascicle was transected and repaired. Four and 5 months postoperatively, the outcome of regeneration was evaluated by histology, by retrograde tracing, and by assessment of the muscle force of the gastrocnemius and tibial anterior muscles. The tracing experiments showed that specificity of muscle reinnervation significantly improved when a barrier was employed, which significantly or clearly improved muscle twitch tension in groups C and D. However, muscle contraction force was not better when fascia was used as barrier. The histological picture indicated that this inferior result in group C-II was due to nerve compression caused by fibrotic scar tissue at the site of the fascia graft. Results of this study show that a pedicle fat flap and Integra used as barrier significantly prevent aberrant reinnervation between two sutured nerve fascicles in adjacency resulting in improved motor recovery in rats. Non-vascularized autologous fascia however, reduces also criss-crossing of regenerating axons between the fascicles, but causes significant nerve compression.

Differentiated Adipose-derived Stem Cells Promote Reinnervation of Rat Skin Flaps

BACKGROUND

Sensory recovery of skin flaps is generally poor unless they are elevated as an innervated flap. The aim of this study was to elucidate if Schwann cell (SC)-like cells differentiated from adipose-derived stem cells (ASCs) could improve the cutaneous nerve regeneration in skin flaps.

METHODS

Microvascular island groin flaps were elevated bilaterally in 32 Lewis rats. On the right flap, the epigastric nerve was resected and ligated (noninnervated flap), and on the left flap, the nerve was crushed (innervated flap). ASCs, SC-like cells differentiated from ASCs (dASCs), SCs, or vehicle were simultaneously injected to the dermal and hypodermal layers of flap. After 20 weeks, the reinnervation pattern of flap was assessed immunohistochemically using a neuronal marker, PGP9.5.

RESULTS

dASC cultures produced significantly higher amount of nerve growth factor and brain-derived neurotrophic factor compared with ASC cultures (P < 0.01), and the level was comparable to that of SC cultures. Although a long-term survival of the transplanted cells was not found, dASCs and SCs significantly increased reinnervation density in the periphery of both types of flaps (P < 0.05), and this effect was more pronounced in noninnervated flaps. On the other hand, ASC transplantation showed no statistically significant effect on the peripheral reinnervation (P > 0.05). In the center of flap, there was no statistically significant increase in reinnervation density in all groups irrespective of flap innervation (P > 0.05).

CONCLUSIONS

dASCs could improve flap reinnervation by 2 mechanisms: First, neurotrophic factors produced by dASCs facilitated regrowth of cutaneous axons from the surroundings of flap. Second, nerve growth factor released by dASCs induced the collateral sprouting of undamaged axons in adjacent tissues. In addition to the use of innervated flaps, dASC transplantation therapy could be a new approach to improve the sensory recovery of skin flaps.

Perineural fat grafting in the treatment of painful end-neuromas of the upper limb: a pilot study

The purpose of this study was to evaluate the effectiveness and middle-term durability of the results achieved with perineural fat grafting of painful neuromas of the upper limb. We retrospectively analysed eight patients, affected by eight neuromas, treated by neuroma excision and fat grafting around the proximal nerve stump. Clinical parameters, the disabilities of the arm shoulder and hand score, and the visual analogue scale were recorded at 2, 6 and 12 months after surgery. A reduction of 23.2% was observed in the mean disabilities of the arm shoulder and hand scores at 12 months. The spontaneous baseline visual analogue scale score showed a mean improvement of 22% at 12 months, although not this was not statistically significant. Perineural fat grafting is a quick and useful procedure and could represent a useful primary operation in the treatment of pain syndromes of neuropatic origin.

Recovery of sensation in immediate breast reconstruction with latissimus dorsi myocutaneous flaps after breast-conservative surgery and skin-sparing mastectomy

In breast reconstruction, sensation in the reconstructed breasts affects the patients' quality of life along with its aesthetic outcome. Fortunately, less invasive procedures such as breast-conservative surgery (BCS) and skin-sparing mastectomy (SSM) have greatly contributed to the improved aesthetic outcome in immediate breast reconstruction. However, there are few reports on the recovery of breast sensation after BCS and SSM. We retrospectively reviewed 104 consecutive patients who underwent immediate breast reconstruction with the latissimus dorsi myocutaneous flap between 2001 and 2006 at our institution. The sensations of pain, temperature, touch, and vibration were examined at the nipple and skin envelope during the follow-up period (range: 12-61 months, mean: 31 months), and a stratified analysis was performed to determine the critical factors affecting the sensation recovery after BCS and SSM. We found that large breast size significantly impaired the recovery of sensation in the nipple and skin envelope after BCS as well as SSM. Older age and high body mass index value were the factors which negatively affected the sensation in the skin envelope after SSM. While all our BCS patients underwent postoperative radiation therapy, it did not negatively affect the recovery of sensation in SSM patients. On the basis of these findings, we could further improve the sensation of the reconstructed breasts after BCS and SSM. Especially after SSM, the use of innervated flaps is recommended in the patients with large breast, increased age, or obesity when the nipple-areola complex is resected.

A comparative microanatomical study on cross-sections of superficial branch of radial nerve in proximal and distal parts of the forearm: a cadaveric study

PURPOSE OF STUDY

Changes in peripheral nerve anatomy with age may be the cause for poor prognosis after nerve repair in elderly cases. The aim of the present study is to find out and compare the cross-sectional microanatomy as well as age-related changes in the non-fascicular components of superficial branch of radial nerve at cubital fossa (SBRN-1) and above wrist (SBRN-2).

METHODS

Thirty-eight fresh human (14 male and five female) cadaveric SBRN-1 and SBRN-2 were collected from both sides of 19 cadavers and study has been performed at different magnifications after routine histological (Masson's trichrome stain) processing was done for morphometric analysis (total cross-sectional area [Asc], fascicular area [Af], non-Af [Anonf], adipose [FAT] area and non-adipose area [nFAT]).

RESULTS

SBRN-1 and SBRN-2 belonged to polyfascicular type and showed difference in amount of connective and adipose tissues in Anonf. The number of fascicles in SBRN-1 ranged from 2 to 6 (3.66±0.21, mean±SEM) and in SBRN-2 ranged from 7.5 to 11.5 (9.24±0.26). On comparing the percentage level of adipose tissue (FAT) in total cross-section area (Asc) and in Anonf of SBRN-1 and SBRN-2, the level of adipose tissue was increased with age.

CONCLUSIONS

The amount of adipose tissue in SBRN-1 and SBRN-2 Anonf was found to be high in most of the elderly cases. On comparison, there was not much difference between SBRN-1 and SBRN-2, but, the fascicle count was found to be increasing gradually from proximal to distal part of the SBRN.

A comparative microanatomical study on cross sections of medial and lateral cutaneous nerves of forearm at the antecubital fossa: a cadaveric study

BACKGROUND

The anterior branch of the medial antebrachial cutaneous nerve of the forearm (AMACN) and the lateral antebrachial cutaneous nerve of the forearm (LACN) are used as potential donor grafts for repairing sensory nerves. A higher percentage of connective tissue plays an important role in predicting prognosis after nerve repair. The aim is to perform a comparative study on cross-sectional microanatomy and age related changes in non-fascicular components of the AMACN and LACN.

METHODS

Thirty six fresh human (from both sides of 14 male and 4 female) cadaveric AMACN and LACN were collected at antecubital fossae and studied at different magnifications for morphometric analysis (total cross-sectional area (Asc), fascicular area (Af) and non-fascicular area (Anonf)), after histological (Masson's trichrome stain) processing.

RESULTS

AMACN and LACN belong to polyfascicular type and showed differences in amount of connective and adipose tissues in non-fascicular areas. In the AMACN, there was less adipose tissue (19.38% in Asc and 25.57% in Anonf) with more collagen fibers (57.28% in Asc and 75.57% in Anonf) and in the LACN, there was more adipose tissue (47.51% in Asc and 58.19% in Anonf) with fewer collagen fibers (34.10% in Asc and 41.76% in Anonf) in interfascicular domains.

CONCLUSIONS

The amount of adipose tissue in LACN non-fascicular area was found to be high at all ages. The presence of less adipose tissue and collagen fibers in the non-fascicular area of the AMACN (below 60 years) could be used for successful nerve grafting when compared to LACN.

Estimations of topographically correct regeneration to nerve branches and skin after peripheral nerve injury and repair

Peripheral nerve injury is typically associated with long-term disturbances in sensory localization, despite nerve repair and regeneration. Here, we investigate the extent of correct reinnervation by back-labeling neuronal soma with fluorescent tracers applied in the target area before and after sciatic nerve injury and repair in the rat. The subpopulations of sensory or motor neurons that had regenerated their axons to either the tibial branch or the skin of the third hindlimb digit were calculated from the number of cell bodies labeled by the first and/or second tracer. Compared to the normal control side, 81% of the sensory and 66% of the motor tibial nerve cells regenerated their axons back to this nerve, while 22% of the afferent cells from the third digit reinnervated this digit. Corresponding percentages based on quantification of the surviving population on the experimental side showed 91%, 87%, and 56%, respectively. The results show that nerve injury followed by nerve repair by epineurial suture results in a high but variable amount of topographically correct regeneration, and that proportionally more neurons regenerate into the correct proximal nerve branch than into the correct innervation territory in the skin.

Morphological and functional evaluation of leg-muscle reinnervation after coupler coaptation of the divided rat sciatic nerve

Mechanical couplers are successfully used for microvascular venous anastomoses. The advantages include a simple and fast technique and a high patency rate. Couplers offer a secluded coaptation site, and might also be of use in peripheral nerve repair. The present study was designed to investigate coupler coaptation of the rat sciatic nerve, evaluating the number and locations of motor and sensory neurons projecting to the selected muscles as well as stimulation-induced muscle contraction force. Adult rats underwent either suture or coupler repair after left sciatic nerve transection. In all rats, the experimental side was compared to the healthy right side. Evaluation after 20 weeks included retrograde labeling of motoneurons and dorsal root ganglion neurons projecting to the tibial anterior muscle and to the tibial posterior muscle, histology, muscle contraction force (tibial anterior muscle and gastrocnemius muscle), and a pinch reflex test. The results show that the suture and the coupler groups did not differ significantly regarding the examined parameters, except for discrete signs of nerve compression at the coaptation site after coupler repair due to fibrous tissue ingrowth. However, this did not impair axonal regeneration. Importantly, axonal outgrowth from the repair site to the surrounding tissue was not observed after coupler coaptation, but it was observed after suture repair. These results suggest that couplers may be of value for repair of nerves in adjacency to avoid axonal crisscrossing between nerves during regeneration.

Reconstruction of complex parotidectomy defects using the lateral arm free tissue transfer

OBJECTIVES

The study goal was to show that the lateral arm flap is a viable reconstructive option for complex parotidectomy defects.Study design and setting We studied a case series at a tertiary care medical center from March 1997 to March 2002. The lateral arm flap was used to reconstruct parotidectomy defects that included a composite resection of adjacent tissue in 30 patients. There were 19 men and 11 women (mean age, 62 years; mean follow-up, 19 months). The mean flap area was 114 cm(2), and the mean flap volume was 172 cm(3). The posterior cutaneous nerve of the forearm (PCNF) was used as a facial nerve cable graft in 14 patients. Facial disability outcomes were measured using the Facial Clinimetric Evaluation scale.

RESULTS

The major and minor complication rates with use of this reconstructive approach were low: 16.7% (5 of 30) and 26.7% (8 of 30), respectively. Donor site morbidity was minimal, with no patient having a major donor site complication and 23.3% (7 of 30) having minor complications. Functional recovery of the facial nerve occurred in 6 of 8 evaluable patients who underwent facial nerve grafting using the PCNF. Controlling for degree of facial nerve paralysis, Facial Clinimetric Evaluation scale scores of our patients were not statistically different than those of a historic population with a facial paralysis and no surgical defect.

CONCLUSIONS

The lateral arm free flap effectively restores facial appearance when used for reconstruction of complex parotidectomy defects. The PCNF, a nerve harvested with the lateral arm flap, can be used as a facial nerve cable graft with a high rate of success.

SIGNIFICANCE

The lateral arm flap is successful as a single donor site for reconstructing facial contour and the facial nerve after major ablative defects in the parotid region.

Hyaluronic acid prevents peripheral nerve adhesion

The purpose of this study was to clarify the effectiveness of hyaluronic acid (HA) in the prevention of scar formation after neurolysis using a rabbit model. In the first stage, the left sciatic nerve was exposed and elevated along a 3 cm section. Then, the surface of the neural bed was coagulated using a bipolar coagulator. Finally, the sciatic nerve was replaced and fixed to the neural bed with 8/0 nylon sutures, and the wound was closed. In the second stage, the adherent sciatic nerve was re-exposed after 6 weeks. In the neurolysis group, a simple neurolysis was performed. In the HA group, the neurolysis was performed in a surgical field coated with HA from the beginning to the end of the operation. In the steroid group, methyl prednisolone acetate was infiltrated at the end of the neurolysis. In the third stage, electrophysiological, histological and biomechanical measurements were taken 6 weeks after the second stage. While there was no significant difference between the HA and the steroid groups, the electrophysiological functions of the HA and steroid groups were significantly better than that of the neurolysis group. Histology showed that the formation of intraneural and extraneural scar tissue was lowest in the HA group, followed by the steroid and neurolysis groups. The tensile strength required to strip the sciatic nerve from the neural bed of the HA group was significantly less than that of the neurolysis group. However, there was no significant difference between the steroid and neurolysis groups. In conclusion, HA effectively reduced scar formation after neurolysis.