Role of topical steroids in reducing dysfunction after nerve injury

Review of Drug Therapy for Peripheral Facial Nerve Regeneration That Can Be Used in Actual Clinical Practice

Although facial nerve palsy is not a life-threatening disease, facial asymmetry affects interpersonal relationships, causes psychological stress, and devastates human life. The treatment and rehabilitation of facial paralysis has many socio-economic costs. Therefore, in cases of facial paralysis, it is necessary to identify the cause and provide the best treatment. However, until now, complete recovery has been difficult regardless of the treatment used in cases of complete paralysis of unknown cause and cutting injury of the facial nerve due to disease or accident. Therefore, this article aims to contribute to the future treatment of facial paralysis by reviewing studies on drugs that aid in nerve regeneration after peripheral nerve damage.

Changes of Functional, Morphological, and Inflammatory Reactions in Spontaneous Peripheral Nerve Reinnervation after Thermal Injury

In recent decades, the use of energy-based devices has substantially increased the incidence of iatrogenic thermal injury to nerves (cauterization, etc.). While recovery of the nerve after thermal injury is important, the changes in neural structure, function, and peripheral inflammatory reactions postinjury remain unclear. This study is aimed at demonstrating the changes mentioned above during the acute, subacute, and chronic stages of nerve reinnervation after thermal injury. Spontaneous reinnervation was evaluated, including the neural structures, nerve conduction abilities, and muscle regeneration. These effects vary depending on the severity of thermal injury (slight, moderate, and severe). Peripheral inflammatory reactions, as impediments to reinnervation, were found in significant numbers 3 days after thermal injury, exhibiting high expression of IL-1β and TNF-α, but low expression of IL-10. Our findings reveal the pathogenesis of peripheral nerve reinnervation after thermal injury, which will assist in selecting appropriate treatments in further research.

Functional recovery with histomorphometric analysis of nerves and muscles after combination treatment with erythropoietin and dexamethasone in acute peripheral nerve injury

Introduction

Peripheral nerve injury (PNI) often leads to significant functional loss in patients and poses a challenge to physicians since treatment options for improving functional outcomes are limited. Recent studies suggest that erythropoietin and glucocoticoids have beneficial effects as mediators of neuro-regenerative processes. We hypothesized that combination treatment with erythropoietin and glucocoticoids would have a synergistic effect on functional outcome after PNI.

Materials and methods

Sciatic nerve crush injury was simulated in ten-week-old male C57BL/6 mice. The mice were divided into four groups according to the type of drugs administered (control, erythropoietin, dexamethasone, and erythropoietin with dexamethasone). Motor functional recovery was monitored by walking track analysis at serial time points up to 28 days after injury. Morphological analysis of the nerve was performed by immunofluorescent staining for neurofilament (NF) heavy chain and myelin protein zero (P0) in cross-sectional and whole-mount nerve preparations. Additionally, morphological analysis of the muscle was performed by Hematoxylin and eosin staining.

Results

Combination treatment with erythropoietin and dexamethasone significantly improved the sciatic functional index at 3, 7, 14, and 28 days after injury. Fluorescence microscopy of cross sectional nerve revealed that the combination treatment increased the ratio of P0/NF-expressing axons. Furthermore, confocal microscopy of the whole-mount nerve revealed that the combination treatment increased the fluorescence intensity of P0 expression. The cross-sectional area and minimum Feret’s diameter of the muscle fibers were significantly larger in the mice which received combination treatment than those in the controls.

Conclusion

Our results demonstrated that combination treatment with erythropoietin and dexamethasone accelerates functional recovery and reduces neurogenic muscle atrophy caused by PNI in mice, which may be attributed to the preservation of myelin and Schwann cell re-myelination. These findings may provide practical therapeutic options for patients with acute PNI.

Closing the Gap Between Mammalian and Invertebrate Peripheral Nerve Injury: Protocol for a Novel Nerve Repair

BACKGROUND

Outcomes after peripheral nerve injuries are poor despite current nerve repair techniques. Currently, there is no conclusive evidence that mammalian axons are capable of spontaneous fusion after transection. Notably, certain invertebrate species are able to auto-fuse after transection. Although mammalian axonal auto-fusion has not been observed experimentally, no mammalian study to date has demonstrated regenerating axolemmal membranes contacting intact distal segment axolemmal membranes to determine whether mammalian peripheral nerve axons have the intrinsic mechanisms necessary to auto-fuse after transection.

OBJECTIVE

This study aims to assess fusion competence between regenerating axons and intact distal segment axons by enhancing axon regeneration, delaying Wallerian degeneration, limiting the immune response, and preventing myelin obstruction.

METHODS

This study will use a rat sciatic nerve model to evaluate the effects of a novel peripheral nerve repair protocol on behavioral, electrophysiologic, and morphologic parameters. This protocol consists of a variety of preoperative, intraoperative, and postoperative interventions. Fusion will be assessed with electrophysiological conduction of action potentials across the repaired transection site. Axon-axon contact will be assessed with transmission electron microscopy. Behavioral recovery will be analyzed with the sciatic functional index. A total of 36 rats will be used for this study. The experimental group will use 24 rats and the negative control group will use 12 rats. For both the experimental and negative control groups, there will be both a behavior group and another group that will undergo electrophysiological and morphological analysis. The primary end point will be the presence or absence of action potentials across the lesion site. Secondary end points will include behavioral recovery with the sciatic functional index and morphological analysis of axon-axon contact between regenerating axons and intact distal segment axons.

RESULTS

The author is in the process of grant funding and institutional review board approval as of March 2020. The final follow-up will be completed by December 2021.

CONCLUSIONS

In this study, the efficacy of the proposed novel peripheral nerve repair protocol will be evaluated using behavioral and electrophysiologic parameters. The author believes this study will provide information regarding whether spontaneous axon fusion is possible in mammals under the proper conditions. This information could potentially be translated to clinical trials if successful to improve outcomes after peripheral nerve injury.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/18706.

Dexamethasone Suppresses Radicular Pain Through Targeting the L-PGDS/PI3K/Akt Pathway in Rats With Lumbar Disc Herniation

PURPOSE

Lumbar disc herniation (LDH) is a frequently occurring disease with unknown etiology, which makes treatment a challenge. The aim of this study was to analyze the effects of dexamethasone on LDH and elucidate the underlying mechanisms.

GENERAL METHODS

An LDH rat model was established by nucleus pulposus implantation. The activity of the lipocalin type prostaglandin D synthase (L-PGDS)/phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) axis was evaluated by Western blotting. Paw withdrawal threshold and paw withdrawal latency were assessed by the Von Frey hairs method and the thermal dolorimeter of Hargreaves, respectively. The 21-point Basso-Beattie-Bresnahan scale was used to assess the locomotor function of rats. Pathological changes in the affected region were analyzed by hematoxylin-eosin staining. Immunofluorescence was used to measure the expression of microtubule-associated protein (MAP-2).

FINDINGS

Lumbar disc herniation markedly increased thermo-mechanical allodynia and induced dorsal root ganglion (DRG) degeneration by inactivating the L-PGS/PI3K/Akt pathway. Dexamethasone restored the L-PGDS/PI3K/Akt pathway and relieved LDH-induced thermo-mechanical allodynia. Furthermore, overexpression and knockdown of L-PGDS respectively attenuated and worsened LDH-triggered thermo-mechanical allodynia and tissue degeneration by modulating the PI3K/Akt pathway. Pretreatment with dexamethasone partially abrogated the effect of L-PGDS knockdown through PI3K/Akt activation.

CONCLUSIONS

Dexamethasone relieves LDH-mediated radicular pain by exerting anti-inflammatory effects and reducing the suppression of L-PGDS induced by LDH. Meanwhile, the activity of the PI3K/Akt pathway was decreased, possibly due to the attenuated inflammation induced by dexamethasone. Our results revealed the underlying mechanism of dexamethasone, which might be helpful in reducing the side effects of dexamethasone and provide more focused therapy in LDH.

Composite nanofibers incorporating alpha lipoic acid and atorvastatin provide neuroprotection after peripheral nerve injury in rats

Despite the new treatment strategies within the last 30 years, peripheral nerve injury (PNI) is still a worldwide clinical problem. The incidence rate of PNIs is 1 in 1000 individuals per year. In this study, we designed a composite nanoplatform for dual therapy in peripheral nerve injury and investigated the in-vivo efficacy in rat sciatic nerve crush injury model. Alpha-lipoic acid (ALA) was loaded into poly lactic-co-glycolic acid (PLGA) electrospun nanofibers which would release the drug in a faster manner and atorvastatin (ATR) loaded chitosan (CH) nanoparticles were embedded into PLGA nanofibers to provide sustained release. Sciatic nerve crush was generated via Yasargil aneurism clip with a holding force of 50 g/cm². Nanofiber formulations were administered to the injured nerve immediately after trauma. Functional recovery of operated rat hind limb was evaluated using the sciatic functional index (SFI), extensor postural thrust (EPT), withdrawal reflex latency (WRL) and Basso, Beattie, and Bresnahan (BBB) test up to one month in the post-operative period at different time intervals. In addition to functional recovery assessments, ultrastructural and biochemical analyses were carried out on regenerated nerve fibers. L-929 mouse fibroblast cell line and B35 neuroblastoma cell line were used to investigate the cytotoxicity of nanofibers before in-vivo experiments. The neuroprotection potential of these novel nanocomposite fiber formulations has been demonstrated after local implantation of composite nanofiber sheets incorporating ALA and ATR, which contributed to the recovery of the motor and sensory function and nerve regeneration in a rat sciatic nerve crush injury model.

Transdermal delivery of 4-aminopyridine accelerates motor functional recovery and improves nerve morphology following sciatic nerve crush injury in mice

Oral 4-aminopyridine (4-AP) is clinically used for symptomatic relief in multiple sclerosis and we recently demonstrated that systemic 4-AP had previously unknown clinically-relevant effects after traumatic peripheral nerve injury including the promotion of re-myelination, improvement of nerve conductivity, and acceleration of functional recovery. We hypothesized that, instead of oral or injection administration, transdermal 4-AP (TD-4-AP) could also improve functional recovery after traumatic peripheral nerve injury. Mice with surgical traumatic peripheral nerve injury received TD-4AP or vehicle alone and were examined for skin permeability, pharmacokinetics, functional, electrophysiological, and nerve morphological properties. 4-AP showed linear pharmacokinetics and the maximum plasma 4-AP concentrations were proportional to TD-4-AP dose. While a single dose of TD-4-AP administration demonstrated rapid transient improvement in motor function, chronic TD-4-AP treatment significantly improved motor function and nerve conduction and these effects were associated with fewer degenerating axons and thicker myelin sheaths than those from vehicle controls. These findings provide direct evidence for the potential transdermal applicability of 4-AP and demonstrate that 4-AP delivered through the skin can enhance in-vivo functional recovery and nerve conduction while decreasing axonal degeneration. The animal experiments were approved by the University Committee on Animal Research (UCAR) at the University of Rochester (UCAR-2009-019) on March 31, 2017.

Peripheral nerve injury and myelination: Potential therapeutic strategies

Traumatic peripheral nerve injury represents a major clinical and public health problem that often leads to significant functional impairment and permanent disability. Despite modern diagnostic procedures and advanced microsurgical techniques, functional recovery after peripheral nerve repair is often unsatisfactory. Therefore, there is an unmet need for new therapeutic or adjunctive strategies to promote the functional recovery in nerve injury patients. In contrast to the central nervous system, Schwann cells in the peripheral nervous system play a pivotal role in several aspects of nerve repair such as degeneration, remyelination, and axonal growth. Several non-surgical approaches, including pharmacological, electrical, cell-based, and laser therapies, have been employed to promote myelination and enhance functional recovery after peripheral nerve injury. This review will succinctly discuss the potential therapeutic strategies in the context of myelination following peripheral neurotrauma.

A morphological and biochemical evaluation of the effects of quercetin on experimental sciatic nerve damage in rats

The present study evaluated the neuroprotective and antioxidant effects of quercetin in a rat model of sciatic nerve crush injury using histopathological, morphometric and biochemical methods. A total of 48 male Sprague Dawley rats, aged 10-12 weeks old were randomly divided into eight groups, consisting of two sham groups (S-7, S-28), three quercetin-treated groups (Q-7, Q-28; 200 mg/kg/7 days), trauma (T-7, T-28; 1 min sciatic nerve crush injury) and three trauma+quercetin groups (T+Q-7, T+Q-28; trauma+quercetin 200 mg/kg/7 days). Rats were sacrificed on day 7 or 28. Oxidant-antioxidant biochemical parameters in nerve tissues from all groups were analyzed using histopathological staining with toluidine blue and Masson's trichrome. DNA fragmentations were identified using terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling in cells from each tissue sample. Degeneration of the axons and myelin sheath, the breakdown of the concentric lamellar structure of the myelin sheath and axonal swelling were observed in groups T-7 and T-28. Myelin sheath thicknesses, nerve fiber diameters and the number of myelinated nerve fibers decreased, while the apoptotic index (AI) increased in the T-7 and T-28 groups. However, it was observed that nerve regeneration began in the T+Q-7 and T+Q-28 groups compared with the sham groups, together with the healing of cellular damage and axonal structure and a decrease in the AI. Malondialdehyde and superoxide dismutase activity did not differ significantly between the T-7 and S-7 groups. However, catalase activity significantly decreased in the T-28 group when compared with the sham 7 day group. Tissue malondialdehyde levels significantly increased, while serum catalase activity increased in the T+Q-7 group compared with the T-7 group. These results suggest that quercetin has beneficial effects on nerve regeneration and may shorten the healing period in crush-type sciatic nerve injuries.

A case series of trigeminal nerve injuries caused by periapical lesions of mandibular teeth

Aims Periapical lesions have been implicated in mandibular trigeminal sensory neuropathy. This study aimed to report on a case series of consecutive patients presenting with mandibular division trigeminal nerve injuries (TNI) caused by periapical lesions. Common presenting characteristics and possible strategies for management were also investigated.Materials and methods A retrospective study of 22 patients with TNI caused by periapical lesions. Data were extracted from patient records and analysed using Microsoft Excel and SPSS. Factors associated with TNI resolution were assessed using Student's t-Tests and one-way Analysis of Variance (ANOVA), where P <0.05 indicated statistical significance.Results Twenty-one patients had inferior alveolar nerve injuries (IANI) and one had a lingual nerve injury (LNI). The most commonly affected teeth were the first molars (11 patients; 50%). TNI symptoms included numbness, pain and/or paraesthesia. IANI resolved completely among five patients within a mean time of 4.7 months (range 1.5-12 months). Patients who showed complete resolution had the affected teeth extracted or primary endodontic treatment with antibiotics.Conclusions Patients with TNI caused by periapical lesions can suffer significantly from combined numbness, pain and paraesthesia. Resolution of these injuries may be maximised upon early diagnosis and treatment of the periapical lesion by tooth extraction or primary endodontic treatment.

Does the combination of erythropoietin and tapered oral corticosteroids improve recovery following iatrogenic nerve injury?

INTRODUCTION

The reported prognosis for recovery after peripheral nerve injury is remarkably poor. Deficits may persist for years, resulting in significant functional disability. Both corticosteroids and Erythropoietin have been investigated as neuroprotective agents; however, their efficacy in total hip and knee arthroplasty is not known. The purpose of this study was to evaluate the effect of systemically-administered Erythropoietin and tapered oral corticosteroids on the recovery of postoperative nerve palsies in the setting of total hip and knee arthroplasty.

METHODS

Eleven patients sustaining postoperative peripheral nerve injuries after total hip or knee arthroplasty were treated acutely with Erythropoietin and tapered oral steroids. Motor and sensory function was assessed clinically pre- and postoperatively until complete motor recovery or for a minimum of 1 year.

RESULTS

Motor loss was complete in seven (64%) patients and partial in four (36%). Seven (64%) patients' symptoms affected the common peroneal nerve distribution and four (36%) had concomitant tibial nerve involvement. Eight (73%) patients experienced full motor recovery at an average of 39 days (range: 3-133 days), and three (27%) had near-complete motor recovery. At final follow up, no patient required assistive devices for ambulation.

CONCLUSIONS

Administration of Erythropoietin coupled with oral tapered steroids for patients sustaining iatrogenic nerve injuries in total hip and knee arthroplasty demonstrated faster and more complete recovery of motor and sensory function compared to previous reports in the literature. This study highlights the importance of further investigation to define the role of each in the setting of acute postoperative nerve palsies.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Effect of topical dexamethasone in reducing dysfunction after facial nerve crush injury in the rat

OBJECTIVE

To date, the effect of topical steroid after a crush injury to rat facial nerve has rarely been reported on. The aim of this study was to investigate the effects of topical dexamethasone on recovery after a crush injury to the rat facial nerve, by functional, electrophysiological, and morphological evaluation.

MATERIALS AND METHODS

We investigated the effects of topical dexamethasone on recovery after a crush injury to rat facial nerve by functional, electrophysiological and morphological evaluation.

RESULTS

The functional recovery using vibrissae movement was significantly high scores in the experimental group than control group at two and three weeks post-crush. The recovery of the threshold of muscle action potential was significantly lowered in the experimental group compared to the control (p<0.05). However, there was no statistical significance in the nerve conduction velocity. The dexamethasone treatment groups showed a larger axon diameter and thicker myelin sheath than the control group.

CONCLUSION

From our results, topical dexamethasone accelerates recovery of the crush-injured facial nerve.

Therapeutic effects of local application of dexamethasone during bilateral sagittal split ramus osteotomy surgery

PURPOSE

Bilateral sagittal split ramus osteotomy (BSSO) is one of the most common procedures used in the treatment of mandibular deformity. One common complication of this surgical procedure is hypoesthesia of the inferior alveolar nerve. The authors hypothesized that perioperative local application of dexamethasone would have positive therapeutic effects on neurosensory function.

MATERIALS AND METHODS

This study investigated 18 patients (10 male, 8 female; mean age, 26.1 ± 4.9 yr) who underwent BSSO. One side of each patient's mandible was randomly selected as the control side and the opposite side as the experimental side. A solution of dexamethasone 4 mg/1 mL was drawn into a syringe and poured directly on the distal segment of the exposed inferior alveolar nerve during splitting and 1 mL was poured on the same nerve immediately before the start of fixation. Neurosensory tests, including light touch, direction of movement, static 2-point touch, thermal stimuli, and pin prick discrimination, were conducted. The χ(2) and Fisher exact tests were used to evaluate the data.

RESULTS

The difference between the control and experimental groups at all intervals was not significant for any of the neurosensory tests.

CONCLUSION

Local application of dexamethasone on the exposed inferior alveolar nerve during BSSO is not recommended.

Dexamethasone topically accelerates peripheral nerve repair and target organ reinnervation: a transected sciatic nerve model in rat

The objective was to assess the effect of topically administered dexamethasone on peripheral nerve regeneration and functional recovery. Sixty male healthy white Wistar rats were divided into four experimental groups (n = 15), randomly: in transected group (TC), left sciatic nerve was transected and stumps were fixed in the adjacent muscle. In treatment group defect was bridged using a silicone tube (SIL/Dexa) filled with 10 μL dexamethasone (0.1 mg/kg). In silicone group (SIL), the tube was filled with phosphate-buffered saline alone. In sham-operated group (SHAM), sciatic nerve was exposed and manipulated. Each group was subdivided into three subgroups of five animals each and regenerated nerve fibres were studied 4, 8 and 12 weeks after surgery. Functional study, gastrocnemius muscle mass and morphometric indices confirmed faster recovery of regenerated axons in SIL/Dexa than SIL group (p < 0.05). In immunohistochemistry, location of reactions to S-100 in SIL/Dexa was clearly more positive than that in SIL group. When loaded in a silicone tube, dexamethasone improved functional recovery and morphometric indices of sciatic nerve. Topical application of this readily available agent offers the benefit of cost savings as well as avoiding the complications associated with systemic administration.

Betamethasone-enhanced vein graft conduit accelerates functional recovery in the rat sciatic nerve gap

PURPOSE

The objective of the study was to assess the effect of topically administered betamethasone on peripheral nerve regeneration and functional recovery after sciatic nerve transection in the rat.

MATERIALS AND METHODS

Forty-five healthy male white Wistar rats were divided into 3 experimental groups (n = 15), randomly. In the treatment group, a 10-mm sciatic nerve defect was bridged by use of an inside-out vein graft filled with 10 μL betamethasone (0.1 mg/kg) (IOVG/BETA group). In the control group, the vein was filled with phosphate-buffered saline solution alone (IOVG group). In the sham surgery group, the sciatic nerve was exposed with no further deleterious manipulations (SHAM group). Each group was subdivided into 3 subgroups of 5 animals each, and the regenerated nerve fibers were studied 4, 8, and 12 weeks after surgery.

RESULTS

Functional study confirmed faster recovery of regenerated axons in the IOVG/BETA group than in the IOVG group (P < .05). Gastrocnemius muscle mass in the IOVG/BETA group was found to be significantly greater than that in the IOVG group (P < .05). Morphometric indices of the regenerated fibers showed that the number and diameter of the myelinated fibers were significantly higher in the IOVG/BETA group than in the control group (P < .05). By use of immunohistochemistry, the location of reactions to S-100 in IOVG/BETA was clearly more positive than that in the IOVG group.

CONCLUSIONS

When loaded in a vein graft, betamethasone resulted in improvement of functional recovery and quantitative morphometric indices of sciatic nerve. Topical application of this readily available agent offers the benefit of cost savings, as well as avoiding the complications associated with systemic administration.

Facial nerve neurorrhaphy and the effects of glucocorticoids in a rat model

OBJECTIVE

After nerve injury, an exaggerated neuroinflammatory process may hinder neuron regeneration and recovery. Immunomodulation using glucocorticoids may therefore improve facial nerve injury outcomes. This study aims to examine the effect of both local and systemic dexamethasone administration on facial nerve functional recovery after axotomy in a rat model.

STUDY DESIGN

Randomized, placebo-controlled, blinded animal study. Setting Animal laboratory.

SUBJECTS AND METHODS

Seventy-four Wistar rats underwent facial nerve axotomy with immediate neurorrhaphy. Rats were randomly assigned a postoperative group: control (no therapy); systemic dexamethasone 0.5, 1, 5, or 10 mg/kg for 3 administrations; or topically applied dexamethasone at 2 or 4 mg/mL. Blinded, standardized facial assessments and nerve conduction studies (NCS) were performed. Gross facial motion assessments were corroborated with vibrissae frequency video analysis.

RESULTS

At 8 weeks, rats receiving systemic dexamethasone at 5 mg/kg attained greater eye blink closure (P = .004) and vibrissae motion (P = .012) compared with controls. Systemic dexamethasone at 0.5, 1, and 10 mg/kg and intraoperative topical application of dexamethasone at 2 or 4 mg/mL did not produce a significant improvement in facial motion compared with controls. Nerve conduction studies show a trend of increased return of compound muscle action potential amplitude levels compared with baseline among rats that received systemic dexamethasone 5 mg/kg but do not achieve statistical significance.

CONCLUSION

In a rat facial nerve axotomy model, high-dose systemic dexamethasone therapy may improve functional recovery when administered in the immediate period following neurorrhaphy.

Altered sensation caused by peri-implantitis: a case report

Frequently reported is a case wherein a lesion caused by periodontitis or periapical lesion in a natural tooth enlarged, invaded the inferior alveolar nerve canal, and induced paresthesia. Cases wherein paresthesia occurred because of peri-implantitis have been rarely reported. The patient in this case report had experienced transient paresthesia after implant placement and recovered normal sensation 3 months later. Thirteen years later, this patient visited the authors' hospital with paresthesia in the same region because the peri-implantitis progressed to the apex of the implant. One week after removal of the implant, sense recovery and pain relief started, and 15 days after removal, the paresthesia and pain completely disappeared. For patients who experience transient paresthesia and recovery owing to nerve damage caused by the placement of an implant in the mandibular molar or premolar area, or in patients in whom the implant is close to the inferior alveolar nerve canal or the mental nerve, the spread of inflammation caused by peri-implantitis can induce paresthesia.

Injury of the Inferior Alveolar Nerve during Implant Placement: a Literature Review

Objectives

The purpose of present article was to review aetiological factors, mechanism, clinical symptoms, and diagnostic methods as well as to create treatment guidelines for the management of inferior alveolar nerve injury during dental implant placement.

Material and Methods

Literature was selected through a search of PubMed, Embase and Cochrane electronic databases. The keywords used for search were inferior alveolar nerve injury, inferior alveolar nerve injuries, inferior alveolar nerve injury implant, inferior alveolar nerve damage, inferior alveolar nerve paresthesia and inferior alveolar nerve repair. The search was restricted to English language articles, published from 1972 to November 2010. Additionally, a manual search in the major anatomy, dental implant, periodontal and oral surgery journals and books were performed. The publications there selected by including clinical, human anatomy and physiology studies.

Results

In total 136 literature sources were obtained and reviewed. Aetiological factors of inferior alveolar nerve injury, risk factors, mechanism, clinical sensory nerve examination methods, clinical symptoms and treatment were discussed. Guidelines were created to illustrate the methods used to prevent and manage inferior alveolar nerve injury before or after dental implant placement.

Conclusions

The damage of inferior alveolar nerve during the dental implant placement can be a serious complication. Clinician should recognise and exclude aetiological factors leading to nerve injury. Proper presurgery planning, timely diagnosis and treatment are the key to avoid nerve sensory disturbances management.

Mandibular nerve neurosensory impairment after dental implant surgery: management and protocol

More than 70% of dentists have experienced patients with postoperative paresthesia/dysesthesia or anesthesia as a result of dental procedures. The most common nerve affected is the mandibular nerve, which may be injured during either implant surgery or bone grafting procedures. However, no organized protocol directed specifically for general dentists, or for the vast majority of specialists, has been published. The protocol presented in this article is divided into 5 periods: during surgery (1) nerve injury is suspected or (2) known nerve transection, post-operative period (3) 1 week and (4) 12 weeks. The appropriate treatment (pharmacology, monitoring, etc.) for each period is suggested, including the referral to a nerve specialist when appropriate.

Systemic Betamethasone Accelerates Functional Recovery After a Crush Injury to Rat Sciatic Nerve

PURPOSE

The aim of the study was to evaluate the effect of perioperatively systemically administered betamethasone on nerve recovery (within or outside a confined space) after induced nerve crush injury.

MATERIALS AND METHODS

The sciatic nerve of 40 adult Wistar rats was crushed. In half of the animals, the injured nerve was entrapped in a silicone tube to simulate the environment of a closed space, and in the other half the nerve was left to heal. Half of the rats in each group were treated with subcutaneous betamethasone (2 mg/kg body weight/day) during the first 24 hours, starting preoperatively, whereas the other half, the control animals, were given the same amount of physiological saline. All animals underwent preoperative and postoperative walking track analysis (toe spread [TS] and intermediate toe spread [ITS]) twice weekly for 6 weeks.

RESULTS

For nonconfined space groups, there was no significant difference between the 2 groups (P = .052 for ITS and P = .315 for TS) during the first 2 weeks. Starting from the end of the second week, animals treated with betamethasone recovered more rapidly than did the controls (P < .001) and continued to do so until the end of the observation period. In the confined space groups, there was a significant difference between the 2 groups for ITS (P < .001) and for TS (P < .05) during the first 2 weeks. The difference continued at almost the same level of significance (P = .001) for ITS, whereas for TS, the difference disappeared after the second week.

CONCLUSIONS

We conclude that short-term perioperative administration of betamethasone has a beneficial effect on the recovery of the injured rat sciatic nerve.

The effects of exogenous nitric oxide donor on motor functional recovery of reperfused peripheral nerve

PURPOSE

To investigate the effects of the nitric oxide donor S-nitroso-N-acetylcysteine (SNAC) on motor functional recovery of reperfused rat sciatic nerve.

METHODS

Seventy-eight rats were divided into groups treated with SNAC (100 nmol/100 g/min), methylprednisolone 30 mg/kg/h for 15 minutes, 45-minute pause, 5.4 mg/kg/h for 1.5 h), and phosphate-buffered saline 0.2 mL/100 g/h). A 1-cm segment of sciatic nerve had 2 hours of ischemia and the results were evaluated after various reperfusion periods using a walking track test, muscle contractile testing, muscle weight, and histology.

RESULTS

During reperfusion there was a significant overall improvement in sciatic functional index measurement and isometric titanic contractile force for the SNAC-treated group compared with the methylprednisolone- and phosphate-buffered saline- treated groups. The SNAC group had significantly earlier improvement in the sciatic functional index measurement between days 7 and 28. Restoration of the contractile force and muscle weight of the extensor digitorum longus muscle began earlier in the SNAC group--after day 11--whereas the other 2 groups showed progressive atrophy until day 21, with a significant difference between the SNAC group and the other 2 groups. Histologic examination showed that SNAC-treated rats had less severe degeneration and earlier regeneration of axons than the others. Although methylprednisolone-treated rats showed earlier recovery than phosphate-buffered saline-treated rats in all parameters there were no significant differences between these 2 groups.

CONCLUSIONS

Supplementation of nitric oxide is effective in promoting motor functional recovery of the reperfused peripheral nerve and has potential to replace or augment steroids as therapeutic agents in treatment of nervous system ischemia/reperfusion injury.

On neurosensory disturbance after sagittal split osteotomy

PURPOSE

The purpose of this retrospective study was to assess the incidence of the neurosensory disturbance (NSD) after sagittal split osteotomy and evaluate NSD in relation to patient age, gender, satisfaction, and effect of steroids.

PATIENTS AND METHODS

Questionnaires were mailed to all patients (31 women, 19 men) who underwent bilateral sagittal split osteotomy between 1995 and 1999, at least 1 year after the operation. Patients were queried about perceived NSD in the distribution of both inferior alveolar and lingual nerves, duration of these changes, and any influence of these changes on their quality of life.

RESULTS

Eighty-six percent of the mailed questionnaires were returned and analyzed (27 women, 16 men). Eight patients with 10 affected sides (11.6% of sides) reported long lasting NSD corresponding to the distribution of the inferior alveolar nerve. NSD was reported in 16.7% of the operated sides in women, while 3% of the operated sides in the men had such changes. Fifty percent of the operated sides in patients over 40 years of age were affected. Steroid treatment seemed to decrease NSD. Four patients (9%) were not satisfied, but only 1 attributed the dissatisfaction to sensory impairment.

CONCLUSION

The incidence of NSD after sagittal split osteotomy increases in patients over the age of 40. Steroid regimen might be beneficial in reducing NSD after sagittal split osteotomy, although further investigation is required. The discomfort of the nerve damage seems outweighed by the result of function and esthetics.

Involvement of gicerin, a cell adhesion molecule, in development and regeneration of chick sciatic nerve

We have examined the role of gicerin, an immunoglobulin superfamily cell adhesion molecule, in chick sciatic nerves during development and regeneration. Gicerin was expressed in the spinal cord, dorsal root ganglion (DRG) and sciatic nerves in embryos, but declined after hatching. Neurite extensions from explant cultures of the DRG were promoted on gicerin's ligands, which were inhibited by an anti-gicerin antibody. Furthermore, gicerin expression was upregulated in the regenerating sciatic nerves, DRG and dorsal horn of the spinal cord after injury to the sciatic nerve. These results indicate that gicerin might participate in the development and regeneration of sciatic nerves.

Dexamethasone decreases blood flow in normal nerves and dorsal root ganglia

STUDY DESIGN

An experimental physiologic and histologic study of dexamethasone effects on peripheral nerves.

OBJECTIVE

To characterize the effect of topically applied 0.4% dexamethasone on acute changes in nerve blood flow and subsequent histologic changes in rat sciatic nerve fibers.

SUMMARY OF BACKGROUND DATA

Dexamethasone is an anti-inflammatory glucocorticoid used clinically to reduce the neural consequences of inflammation. Several reports of accidental injury to nerves after steroid injections have raised questions about the mechanisms involved in dexamethasone-induced neurotoxic injury.

METHODS

Nerve blood flow studies using a laser Doppler flowmeter were conducted in animals with stable temperature and arterial pressure. Dexamethasone 0.4%, 0.1 mL was applied topically to rat sciatic nerve in the following protocol groups: 1) nerve blood flow recording every 5 minutes for 30 minutes, and 2) initial nerve blood flow recording and repeat recording at 4 hours. Three additional animals had 30-minute nerve blood flow recordings in which normal saline was substituted for dexamethasone; these animals were used for control and to assure that the experimental preparation was viable throughout the observational period. Additional groups of two animals each received dexamethasone but were used only for neuropathologic observation at 2, 4, and 6 days after treatment. Neuropathologic studies were conducted on glutaraldehyde-fixed, plastic-embedded tissue.

RESULTS

Application of saline to the exposed sciatic nerves did not significantly change nerve blood flow from baseline values. Nerve blood flow values remained constant throughout the observational period. Dexamethasone, however, significantly reduced nerve blood flow in both the 30-minute and 4-hour groups. Some animals showed an initial transient increase in blood flow before nerve blood flow began to steadily decline to the final values reported. Neuropathologic changes were minimal and consisted only of edema and occasional subperineurial activation of Schwann cells. No demyelination or degeneration was seen.

CONCLUSION

Dexamethasone causes statistically significant reductions in normal nerve blood flow at 30 minutes and 4 hours after topical application; however, the reduction is on average below the threshold for causing ischemic changes in the structure of peripheral nerve fibers.