The use of autogenous vein grafts for inferior alveolar and lingual nerve reconstruction

Surgical outcomes of the surgical techniques following management of iatrogenic trigeminal nerve injuries: A systematic review

Objective

To investigate the effectiveness of the microsurgical treatment in restoring full sensory recovery following trigeminal nerve injuries caused by iatrogenic oral and maxillofacial surgical interventions.

Methods

A detailed search was conducted on the Cochrane central register of controlled trials, Medline and Embase. Clinical studies with at least twelve months of follow up were included and assessment of risks of bias was made using the Robbin I assessment tool.

Results

Six studies were identified in the searches which include 227 patients. The lingual nerve was the most common injured nerve, followed by the inferior alveolar nerve. Third molar removal was the most frequent cause of nerve injury, followed by root canal treatment, pathology excision, coronectomy, orthognathic surgery, dental implants and then local anaesthetic injections. Overall, surgical interventions for nerve injuries showed neurosensory improvement postoperatively in the majority of patients.

Conclusion

Direct neurorrhaphy is still the gold-standard technique when the tension at the surgical site is minimal. Promising results have been noted on conduit applications following traditional repair or grafting. Further research is needed on the efficacy of allografting and conduit applications in nerve repair.

Neurosensory recovery of inferior alveolar nerve gap reconstruction: a systematic review

Numerous procedures can potentially injure the inferior alveolar nerve during oral and maxillofacial surgery, eventually causing loss or alteration of local sensitivity. When its total rupture occurs, a conduit, such as an autogenous graft, can be used to join it. Due to the morbidity resulting from this technique, alternative forms of sensorineural repair have been investigated. This systematic review includes an electronic search of PubMed, Embase, LILACS, and Web of Science databases, in addition to a grey literature and manual search. Article selection was performed by two independent researchers following a predetermined inclusion criterion: human studies evaluating the regression of sensorineural disorders after any form of grafting (autogenous, allogeneic, and synthetic). Of the 789 studies, 648 were analysed. Only 11 articles met the eligibility criteria. After analysing the results, it was noted that regaining normal sensitivity was uncommon, but the majority of reconstructed nerves recovered their protective abilities. Allografts showed success rates similar to autogenous grafts, making them a viable alternative. However, clinical trials are still needed to provide solid evidence. Prognosis for sensory recovery was impacted by grafting time and patient age.

Efficacy of platelet-rich fibrin and tacrolimus on facial nerve regeneration: an animal study

This study was performed to investigate the effect of platelet-rich fibrin membrane (PRFM), alone and with topical tacrolimus application, on regeneration of the crushed facial nerve (FN). Thirty healthy 7-week-old albino rats were used. The left FN was damaged by crushing in all rats. Three random groups of rats were formed: group 1, untreated; group 2, treated with PRFM; group 3, treated with PRFM plus topical tacrolimus. Functional recovery and histological and immunohistochemical evaluations were performed 4 and 8 weeks later. Anti-S100 was used to detect myelin sheath. At 4 weeks, blinking reflex recovery was more rapid in group 3 than in groups 2 and 1 (4.30 ± 0.48, 3.40 ± 0.52, and 2.20 ± 0.42, respectively); the difference was statistically significant (P = 0.001). Histologically, group 3 showed more apparent normal FN structures than the other groups. Immunohistochemical caspase-3 evaluation of the axon area revealed a significant difference between group 2 (PRFM alone; 8.67 ± 0.029) and group 3 (PRFM plus topical tacrolimus; 4.42 ± 0.028) (P = 0.001). Group 3 showed the greatest positive staining in the myelin sheath. Based on the results of this animal study, clinical studies should be performed to determine whether the combination of PRF and tacrolimus also improves the outcome of nerve regeneration in humans.

Injuries of the Peripheral Mandibular Nerve, Evaluation of Interventions and Outcomes: A Systematic Review

Trigeminal nerve injuries are common and there is currently no consensus on both timing and type of intervention to achieve the best outcomes. A systematic review was performed to compare the outcomes of the many different types of therapeutic interventions for nerve injury. PubMed, EBSCO, and Cochrane Review databases were used to search for studies published from January 1, 2000 to December 31, 2019. Included studies detailed treatment of an injury to peripheral branches of the trigeminal nerve, either known transection or injury causing persistent alteration in sensation. The primary outcome was functional sensory recovery via the Medical Research Council scale. Twenty studies were included, detailing outcomes of 608 subjects undergoing intervention for 622 nerve injuries. Surgical interventions were able to achieve functional sensory recovery in approximately >80% or more of the subjects. There was heterogeneity among how procedures were performed, timing to intervention, and methods of measuring recovery. The data of this study supports the ability of surgical intervention to achieve functional sensory recovery in a significant number of subjects, and found evidence for better outcomes with intervention closer to the time of injury.

Recovery of Sensation Over the Distribution of the Inferior Alveolar Nerve Following Mandibular Resection Without Nerve Reconstruction

PURPOSE

To assess the long-term recovery of sensation in the lower lip after mandibular resection without reconstruction of the inferior alveolar nerve.

MATERIAL AND METHODS

Thirty patients who had mandibular resection carried out without reconstruction of the inferior alveolar nerve were examined after an interval ranging from 6 to 33 years.

RESULTS

Only 1 patient, seen 10 years after resection, was totally numb over the distribution of the inferior alveolar nerve. The other 29 patients had some return of sensation and many had a significant return, though it may take several years to reach the final result. Utilizing the MRC scale 70% of patients achieved S3 (return of superficial cutaneous pain and tactile sensibility without over response) CONCLUSION: This study can serve as a baseline for comparison with patients who have had mandibular resection with reconstruction of the inferior alveolar nerve to assess if this procedure improves the outcomes.

Type I Collagen-Based Devices to Treat Nerve Injuries after Oral Surgery Procedures. A Systematic Review

The regeneration of nerve injuries after oral surgery procedures is a quite often attempted procedure in dental medicine. Despite several proposed technical approaches, there is still a lack of consensus on which should be considered the gold standard procedure, even-though in the last decades, the use of collagen-based devices allowing a tension-free direct neurorrhaphy has been used. A systematic search of multiple electronic databases and hand searching was conducted to assess the level of evidence behind the use of type I collagen devices to treat nerve injuries after oral surgery procedures. After screening, four articles (one case series and three retrospective studies) including overall 65 patients suffering from inferior alveolar (IAN)/lingual nerve (LN) injury after mandibular wisdom tooth extraction, met the inclusion criteria and could be included. The Oxford Centre for evidence-based medicine (OCEBM) scaling system was used to evaluate the quality of the included studies. Positive clinical results in terms of sensorial improvements were recorded at least 3 months after surgery, even-though the overall level of evidence is low. The use of collagen membranes to enhance nerve regeneration in oral surgery results in promising results. Nevertheless, additional clinical comparative trials with larger sample sizes are needed.

Outcomes of Direct Lingual Nerve Repair After an Injury: A Systematic Review

PURPOSE

The purpose of this study was to conduct a systematic review with meta-analysis to investigate the outcomes of direct lingual nerve repair after injury.

MATERIALS AND METHODS

The studies in this review were compiled by using PubMed/Medline and ScienceDirect, which were searched by a single reviewer (M.K.) from their inception until March 10, 2020. Two independent reviewers (M.K. and V.B.Z.) who were blinded to each other's assessments reviewed full-text articles to assess for study inclusion. Outcomes were dichotomized as either functional sensory recovery (FSR) or no FSR. Clinical testing must have been assessed at a minimum of 6 months postoperatively. FSR was defined as grade S3, S3⁺, or S4 on the British Medical Research Council scale of neurosensory function. Studies were only eligible if they provided the number of patients treated with conduits or time from injury to repair and the associated rates of FSR with each intervention.

RESULTS

The initial search using the key terms yielded 4,921 results, which was then eventually filtered down to 6 articles after multiple levels of appraisal. Five articles were retrospective cohort studies and 1 was a randomized controlled study. Four of the 6 studies reported an FSR of grade S3 or higher in 85% or more of the patients. Conduit use was not associated with a significantly greater likelihood of achieving FSR (pooled risk ratio = 1.10; 95% confidence interval, 0.96 to 1.27; P = .17). Repair within 6 months was associated with significantly improved likelihood of achieving FSR (pooled risk ratio = 0.84; 95% confidence interval, 0.71 to 0.99; P = .04).

CONCLUSIONS

The use of conduits during repair was not associated with clinically significant increased FSR. Early repair was associated with a beneficial effect on FSR; however, heterogeneity was an issue with the studies. There is a lack of strong evidence owing to the nature of studies analyzed and the need for further research is required.

Sensory Restoration of the Facial Region

Normal sensitivity of the face is very important for preserving its integrity and function as an efferent source of information for the brain. The trigeminal nerve, which is the largest cranial nerve, conducts most of facial sensory function through its 3 branches: the ophthalmic nerve (V1), the maxillary nerve (V2), and the mandibular nerve (V3). The trigeminal nerve may be damaged by a variety of etiologies including inflammatory disorders, brain tumor resection, trauma, iatrogenic injury, or congenital anomalies. Temporary or permanent damage can lead to numbness, lip-biting injury, corneal anesthesia, and, in the worst scenario, even blindness. Different age groups, mechanisms of the injury, and the time between injury and repair can affect the final result of the nerve repair. Unlike the well-understood facial nerve palsy, so far there is no universal approach to restore the facial sensory function. This article serves to thoroughly review the basic anatomy of trigeminal nerve, diagnosis of sensory nerve dysfunction, and attempts to establish a protocol for treatment and rehabilitation of affected patients.

An Anatomical Feasibility Study Using a Great Auricular Nerve Graft for Ipsilateral Inferior Alveolar Nerve Repair

The great auricular nerve (GAN) has been used for trigeminal and facial nerve repair and the inferior alveolar nerve (IAN) are often sacrificed during segmental mandibulectomy. To our knowledge, only 1 case report has discussed IAN repair using GAN after segmental mandibulectomy. The goal of this study is to clarify the feasibility of using GAN for IAN repair. Eleven sides from 6 fresh frozen Caucasian cadavers were used for this study. The mean age at the time of death was 82.3 years. A submandibular skin incision was made 2 finger breadths below and parallel to the inferior border of the mandible. The GAN was identified and then the mental foramen was found via extraoral dissection. The buccal cortical bone was removed 5 mm posterior to the mental foramen to the wisdom tooth area. Next, the anteroposterior length of the window was measured. The diameter of the IAN at the first molar tooth area was measured. Finally, the GAN was cut with maximum available length to compare to the length of the window in the mandible. The anteroposterior length of the window and diameter of the IAN ranged from 23.1 to 31.2 mm and 1.2 to 2.1 mm, respectively. The length of the available GAN was longer than the ipsilateral bony window of the mandible on all sides. This study might encourage surgeons to consider a new way to treat patients who undergo segmental resection of the mandible with surgical neck dissection with injury to their IAN.

A case report of a long-term abandoned torn lingual nerve injury repaired by collagen nerve graft induced by lower third molar extraction

Background

The lingual nerve plays an important role in multiple functions, including gustatory sensation and contact sensitivity and thermosensitivity. Misdiagnosed conservative treatments for serious lingual nerve (LN) injuries can induce the patient to serious mental disability. After continuous observation and critical diagnosis of the injury, in cases involving significant disruption of lingual nerve function, microneurosurgical reconstruction of the nerve is recommended. Direct anastomosis of the torn nerve ends without tension is the recommended approach. However, in cases that present significant gaps between the injured nerve ends, nerve grafts or conduits (tubes of various materials) are employed. Recently, various reconstruction materials for peripheral nerves were commercially offered especially in the USA, but the best method and material is still unclear in the world. There currently exists no conventional protocol for managing LN neurosensory deficiency in regard to optimal methods and the timing for surgical repair. In Japan, the allograft collagen nerve for peripheral nerves reconstruction was permitted in 2017, and we tried to use this allograft nerve and got a recommendable result.

Case presentation

This report is a long-term abandoned torn LN reconstructed with allograft nerve induced by the lower third molar extraction.

Conclusions

In early sick period, with the exact diagnosis, the LN disturbance should be managed. In a serious condition, the reconstruction with allograft nerve is one of the recommendable methods.

Management and prevention of third molar surgery-related trigeminal nerve injury: time for a rethink

Trigeminal nerve injury as a consequence of lower third molar surgery is a notorious complication and may affect the patient in long term. Inferior alveolar nerve (IAN) and lingual nerve (LN) injury result in different degree of neurosensory deficit and also other neurological symptoms. The long term effects may include persistent sensory loss, chronic pain and depression. It is crucial to understand the pathophysiology of the nerve injury from lower third molar surgery. Surgery remains the most promising treatment in moderate-to-severe nerve injuries. There are limitations in the current treatment methods and full recovery is not commonly achievable. It is better to prevent nerve injury than to treat with unpredictable results. Coronectomy has been proved to be effective in reducing IAN injury and carries minimal long-term morbidity. New technologies, like the roles of erythropoietin and stem cell therapy, are being investigated for neuroprotection and neural regeneration. Breakthroughs in basic and translational research are required to improve the clinical outcomes of the current treatment modalities of third molar surgery-related nerve injury.

Vein Graft Interposition: A Training Model Using Gradually Thawed Cryopreserved Vessels

INTRODUCTION

Microsurgical interposition of vein grafts is an extraordinarily filigree surgical technique, which requires both sound theoretical knowledge and solid manual skills. Although there are a large number of training models, the majority of these are either relatively expensive, technically complex, or employ synthetic materials with poor resemblance to human tissue. The authors' model allows training of ex vivo vein graft interposition on gradually thawed cryopreserved vessels and it, therefore, is cost-efficient and readily available when needed. Furthermore, it respects the 3R-principle (Reduce-Refine-Replace), as it is based on rat cadaveric vessels.

METHODS

Three trainees with basic microsurgical experience, but without prior performance of vein graft interpositioning, were chosen to perform 20 femoral vein graft (5 mm) interpositions into femoral artery defects. The patency and leakage rate served as qualitative variable and operation time as a quantitative variable for efficiency control.

RESULTS

For the first half of trials, the trainees had a patency failure rate of 50% and for the second half a rate of 13.3%. The leakage rate noticeably decreased from 44.4% in the first half of trials to 10% in the second half. Although the trainees needed 60 minutes on average for their first 10 trials, they improved to 51 minutes for their last 10 anastomoses.

CONCLUSION

The authors' microsurgical model offers a simple, low-cost simulation training, specifically designed for learning of vein graft interposition into arterial defects. The model is associated with a high learning curve, based on an objective control of the anastomoses by assessment of the patency, leakage, and operation time.

Neuropathic Pain Due to Iatrogenic Lingual Nerve Lesion: Nerve Grafting to Reduce Otherwise Untreatable Pain

Iatrogenic lingual nerve lesion is a well-known and unfortunate complication after mandibular third molar removal. Occasionally, the nerve injury can cause severe neuropathic pain.Here, the authors present the history of 2 patients with lingual nerve injury due to mandibular third molar removal, and with severe neuropathic pain in the craniomandibular region. Pharmacotherapy and physiotherapy did not reduce the pain, and ultimately, the lingual nerve was surgically explored. Scar tissue and a lingual nerve neuroma were observed and resected in both patients.In the first patient, the gap between the nerve stumps was bridged with an autologous sural nerve graft. In the second patient, some continuity of the lingual nerve was preserved and the resected part was substituted with an autologous sural nerve graft. Significant pain reduction was achieved in both patients and no further medical treatment was necessary at the end of follow-up.These reports show that lingual nerve reconstruction can be a successful therapy in patients experiencing severe neuropathic pain after iatrogenic lingual nerve injury. Different treatment options for neuropathic pain due to lingual nerve injury are discussed.

Treatment modalities and risk factors associated with refractory neurosensory disturbances of the inferior alveolar nerve following oral surgery: a multicentre retrospective study

Little research has been conducted into hypoesthesia, and no studies have elucidated the risk factors for refractory hypoesthesia and compared treatment modalities. The purpose of this multicentre retrospective cohort study was to investigate the relationships between various risk factors, treatment modalities, and refractory hypoesthesia. Risk factors for refractory hypoesthesia after oral surgery were evaluated using univariate and multivariate analysis. To minimize the selection bias associated with a retrospective data analysis, a propensity score analysis was performed between the medication and non-medication groups (65 sites in each group). Moderate or severe hypoesthesia (odds ratio 13.42) and no or late administration of ATP/vitamin B12 (odds ratio 2.28) were significantly associated with refractory hypoesthesia. In the propensity score analysis, the incidence rate of refractory hypoesthesia in the medication group was lower than that in the non-medication group (P<0.001). This study demonstrated the multivariate relationships between various risk factors, treatment modalities, and refractory hypoesthesia. Moderate or severe hypoesthesia and no or late administration of ATP/vitamin B12 were significantly associated with refractory hypoesthesia. Therefore, clinicians should consider these risk factors and initiate early oral administration of ATP/vitamin B12 in cases of hypoesthesia.

[Inferior alveolar nerve reconstruction after segmental resection of the mandible]

INTRODUCTION

The sacrifice of inferior alveolar nerve (IAN) is usual in case of resection of mandibular tumors and is responsible for disabling sensory disorders, drooling and lip incompetence. We report the case of a reconstruction of the IAN by means of an autologous nerve graft after segmental resection of the mandible.

OBSERVATION

A 27-year-old man presented with a recurrence of mandibular ameloblastoma. Treatment consisted in segmental mandibulectomy with resection of the IAN. Bone reconstruction was performed with a fibula free flap and IAN reconstruction was obtained by mean of a 7-cm nerve graft obtained from the greater auricular nerve (GAN). At the 6th postoperative month, the patient had recovered a normal sensitivity of his lower lip and chin. Latency of somatosensory evoked potentials was similar for both sides.

DISCUSSION

The repair of the IAN by nerve autograft is a simple procedure that allows for good sensitive rehabilitation. The use of the GAN is well suited from its anatomy and from the moderate ear sensory sequelae.

Longitudinal Treatment Outcomes of Microsurgical Treatment of Neurosensory Deficit after Lower Third Molar Surgery: A Prospective Case Series

Objective

To prospectively evaluate the longitudinal subjective and objective outcomes of the microsurgical treatment of lingual nerve (LN) and inferior alveolar nerve (IAN) injury after third molar surgery.

Materials and Methods

A 1-year longitudinal observational study was conducted on patients who received LN or IAN repair after third molar surgery-induced nerve injury. Subjective assessments (“numbness”, “hyperaesthesia”, “pain”, “taste disturbance”, “speech” and “social life impact”) and objective assessments (light touch threshold, two-point discrimination, pain threshold, and taste discrimination) were recorded.

Results

12 patients (10 females) with 10 LN and 2 IAN repairs were recruited. The subjective outcomes at post-operative 12 months for LN and IAN repair were improved. “Pain” and “hyperaesthesia” were most drastically improved. Light touch threshold improved from 44.7g to 1.2g for LN repair and 2g to 0.5g for IAN repair.

Conclusion

Microsurgical treatment of moderate to severe LN injury after lower third molar surgery offered significant subjective and objective sensory improvements. 100% FSR was achieved at post-operative 6 months.

Evidence-based outcomes following inferior alveolar and lingual nerve injury and repair: a systematic review

The inferior alveolar nerve (IAN) and lingual (LN) are susceptible to iatrogenic surgical damage. Systematically review recent clinical evidence regarding IAN/LN repair methods and to develop updated guidelines for managing injury. Recent publications on IAN/LN microsurgical repair from Medline, Embase and Cochrane Library databases were screened by title/abstract. Main texts were appraised for exclusion criteria: no treatment performed or results provided, poor/lacking procedural description, cohort <3 patients. Of 366 retrieved papers, 27 were suitable for final analysis. Treatment type for injured IANs/LNs depended on injury type, injury timing, neurosensory disturbances and intra-operative findings. Best functional nerve recovery occurred after direct apposition and suturing if nerve ending gaps were <10 mm; larger gaps required nerve grafting (sural/greater auricular nerve). Timing of microneurosurgical repair after injury remains debated. Most authors recommend surgery when neurosensory deficit shows no improvement 90 days post-diagnosis. Nerve transection diagnosed intra-operatively should be repaired in situ; minor nerve injury repair can be delayed. No consensus exists regarding optimal methods and timing for IAN/LN repair. We suggest a schematic guideline for treating IAN/LN injury, based on the most current evidence. We acknowledge that additional RCTs are required to provide definitive confirmation of optimal treatment approaches.

[Suture of lingual nerve: Technical note]

INTRODUCTION

Because of its anatomical position, the lingual nerve may be severed during oral surgical procedures, such as third molar removal. Early suturing of the nerve promotes better recovery. We describe the end-to-end suture of this nerve.

OPERATIVE PROCEDURE

The suture is carried-out under general anesthesia. The approach is made in the mouth floor, in the same way as for submandibular gland lithiasis transoral removal. This approach allows good exposure and some laxity to displace the nerve stumps. The latter can then be sutured under microscope assistance before closing the mucosa.

DISCUSSION

Lingual nerve suture is a simple, quick and inexpensive procedure. Unlike other procedures, it cannot be used in case of large loss of substance because of the small amount of laxity of the nerve. Nerve function recovery is better if performed before the 6th post-traumatic month, and in young patients.

Clinical outcomes for Conduits and Scaffolds in peripheral nerve repair

The gold standard of peripheral nerve repair is nerve autograft when tensionless repair is not possible. Use of nerve autograft has several shortcomings, however. These include limited availability of donor tissue, sacrifice of a functional nerve, and possible neuroma formation. In order to address these deficiencies, researchers have developed a variety of biomaterials available for repair of peripheral nerve gaps. We review the clinical studies published in the English literature detailing outcomes and reconstructive options. Regardless of the material used or the type of nerve repaired, outcomes are generally similar to nerve autograft in gaps less than 3 cm. New biomaterials currently under preclinical evaluation may provide improvements in outcomes.

Visualization analysis of research frontiers and trends in nerve regeneration and osseoperception in the repair of tooth loss

This study analyzed 85 articles indexed by the Web of Science concerning nerve regeneration and osseoperception during tooth loss repair. Using the Web of Science database and Citespace III software, a document co-citation network map was drawn by document co-citation analysis and word frequency analysis methods. Combined with emergent node secondary literature retrieval, subject headings with apparent changing word frequency trends were retrieved so as to identify research frontiers and development trends. Research frontiers and hotspots for neuronal calcium sensor protein were quantitatively explored to forecast future research developments in nerve regeneration and osseoperception during repair of tooth loss.

The vascularized sural nerve graft based on a peroneal artery perforator for reconstruction of the inferior alveolar nerve defect

The sural nerve has been described for nerve reconstruction of the maxillofacial region since it provides many advantages. We report a case of a vascularized sural nerve graft based on a peroneal artery perforator for immediate reconstruction after the removal of intraosseous neuroma originating in the inferior alveolar nerve. The patient had a neuroma caused by iatrogenic injury to the inferior alveolar nerve. A 4-cm long neuroma existed in the inferior alveolar nerve and was resected. A peroneal perforator was chosen as the pedicle of the vascularized sural nerve graft for the nerve gap. The graft including the skin paddle for monitoring the perfusion supplied by this perforator was transferred to the lesion. The nerve gap between the two stumps of the inferior alveolar nerve was repaired using the 6-cm long vascularized sural nerve. The perforator of the peroneal artery was anastomosed to the branch of the facial artery in a perforator-to-perforator fashion. There was no need to sacrifice any main arteries. The skin paddle with 1 cm × 3 cm in size was inset into the incised medial neck. Perceptual function tests with a Semmes-Weinstein pressure esthesiometer and two-point discrimination in the lower lip and chin at 10 months after surgery showed recovery almost to the level of the normal side. This free vascularized sural nerve graft based on a peroneal artery perforator may be a good alternative for reconstruction of inferior alveolar nerve defects.

Interventions for iatrogenic inferior alveolar and lingual nerve injury

BACKGROUND

Iatrogenic injury of the inferior alveolar or lingual nerve or both is a known complication of oral and maxillofacial surgery procedures. Injury to these two branches of the mandibular division of the trigeminal nerve may result in altered sensation associated with the ipsilateral lower lip or tongue or both and may include anaesthesia, paraesthesia, dysaesthesia, hyperalgesia, allodynia, hypoaesthesia and hyperaesthesia. Injury to the lingual nerve may also affect taste perception on the affected side of the tongue. The vast majority (approximately 90%) of these injuries are temporary in nature and resolve within eight weeks. However, if the injury persists beyond six months it is deemed to be permanent. Surgical, medical and psychological techniques have been used as a treatment for such injuries, though at present there is no consensus on the preferred intervention, or the timing of the intervention.

OBJECTIVES

To evaluate the effects of different interventions and timings of interventions to treat iatrogenic injury of the inferior alveolar or lingual nerves.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Oral Health Group's Trial Register (to 9 October 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 9), MEDLINE via OVID (1946 to 9 October 2013) and EMBASE via OVID (1980 to 9 October 2013). No language restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

Randomised controlled trials (RCTs) involving interventions to treat patients with neurosensory defect of the inferior alveolar or lingual nerve or both as a sequela of iatrogenic injury.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by The Cochrane Collaboration. We performed data extraction and assessment of the risk of bias independently and in duplicate. We contacted authors to clarify the inclusion criteria of the studies.

MAIN RESULTS

Two studies assessed as at high risk of bias, reporting data from 26 analysed participants were included in this review. The age range of participants was from 17 to 55 years. Both trials investigated the effectiveness of low-level laser treatment compared to placebo laser therapy on inferior alveolar sensory deficit as a result of iatrogenic injury.Patient-reported altered sensation was partially reported in one study and fully reported in another. Following treatment with laser therapy, there was some evidence of an improvement in the subjective assessment of neurosensory deficit in the lip and chin areas compared to placebo, though the estimates were imprecise: a difference in mean change in neurosensory deficit of the chin of 8.40 cm (95% confidence interval (CI) 3.67 to 13.13) and a difference in mean change in neurosensory deficit of the lip of 21.79 cm (95% CI 5.29 to 38.29). The overall quality of the evidence for this outcome was very low; the outcome data were fully reported in one small study of 13 patients, with differential drop-out in the control group, and patients suffered only partial loss of sensation. No studies reported on the effects of the intervention on the remaining primary outcomes of pain, difficulty eating or speaking or taste. No studies reported on quality of life or adverse events.The overall quality of the evidence was very low as a result of limitations in the conduct and reporting of the studies, indirectness of the evidence and the imprecision of the results.

AUTHORS' CONCLUSIONS

There is clearly a need for randomised controlled clinical trials to investigate the effectiveness of surgical, medical and psychological interventions for iatrogenic inferior alveolar and lingual nerve injuries. Primary outcomes of this research should include: patient-focused morbidity measures including altered sensation and pain, pain, quantitative sensory testing and the effects of delayed treatment.

Lingual nerve deficit following mandibular third molar removal: review of the literature and medicolegal considerations. Oral Surg Oral Med Oral Pathol Oral Radiol. 2012;113:e10-e18. [PMID: 22669152 DOI: 10.1016/j.tripleo.2011.06.034]

The removal of mandibular third molars is probably the most frequently performed procedure in oral and maxillofacial surgery, and it is the most common surgical procedure associated with lingual nerve deficit. Lingual sensory impairment remains a clinical problem in oral and maxillofacial surgery and has serious medical and legal implications. In fact, damage to the lingual nerve is a common cause of litigation in dentistry. The purpose of this article was to review the literature about lingual nerve deficit following mandibular third molar removal and discuss the associated medicolegal aspects.

Facial nerve repair with Gore-Tex tube and adipose-derived stem cells: an animal study in dogs

PURPOSE

Synthetic conduits have been considered a viable option in nerve reconstructive procedures. They address the goal of entubulization and eliminate the disadvantages of autografts. However, despite all successful reports, none has contained regeneration characteristics, such as growth factors or essential cells, for nerve repair. The authors evaluated the capability of adipose-derived stem cells in Gore-Tex tubes to enhance facial nerve repair.

MATERIALS AND METHODS

Undifferentiated mesenchymal stem cells were extracted from the autogenous adipose tissues of 7 mongrel dogs. The frontal branch of the facial nerve was transected. A gap size of 7 mm was repaired with an expanded polytetrafluoroethylene tube filled with undifferentiated adipose-derived stem cells encapsulated in alginate hydrogel. The control sides were repaired with the tube and alginate alone. The healing phase was 12 weeks.

RESULTS

Except in 2 control sides, an organized neural tissue was formed within the tubes. Compared with the normal nerve diameter, there was a decreased ratio of 29% and 39% in the experimental and control groups, respectively. Neurofilament-positive axon counts were 67% of normal values in the 2 groups. There was no significant difference between groups in histomorphometric parameters. Nerve conduction velocity in the experimental group (28.5 ± 3.5 m/s) was significantly greater than in the control group (16.2 ± 7 m/s). The experimental group also exhibited a greater maximal amplitude of action potential (1.86 ± 0.24 mV) than the control group (1.45 ± 0.49 mV).

CONCLUSIONS

Addition of stem cells in the Gore-Tex tube enhanced the neural repair from a functional standpoint. However, for better functional and histologic results, differentiated Schwann cells and other mediators may be warranted.

Treatment modalities of neurosensory deficit after lower third molar surgery: a systematic review

PURPOSE

To conduct a systematic review to answer the clinical question, "What are the available treatment modalities and their outcomes of neurosensory deficit after lower third molar surgery?"

MATERIALS AND METHODS

A systematic search, including a computer search of several databases with specific keywords, a reference search, and a manual search of 3 key maxillofacial journals were performed. Relevant articles were then evaluated and those that fulfilled the 6 predetermined criteria were chosen to enter the final review. The various treatment modalities and their outcomes of neurosensory deficit after lower third molar surgery, in the selected studies in the final review, were analyzed.

RESULTS

Ten articles entered the final review. Six treatment modalities of lingual nerve or inferior alveolar nerve deficit after lower third molar surgery were identified. External neurolysis, direct suturing, autogenous vein graft, and a Gore-Tex tube as a conduit were the 4 surgical treatments. Significant improvement after surgical treatment ranged from 25% to 66.7%. Acupuncture and low-level laser therapy were 2 available nonsurgical treatment modalities that were found to have produced significant improvement in sensation after treatment in more than 50% of subjects. There was insufficient information to determine the best timing of treatment of nerve injury after third molar surgery.

CONCLUSIONS

Four surgical treatments and 2 nonsurgical treatments were identified in the management of neurosensory disturbance after lower third molar surgery. Most treatments showed an improvement in sensation but the outcomes were variable. Complete recovery was uncommon in all kinds of available treatments.

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.

Construction of tissue engineered nerve grafts and their application in peripheral nerve regeneration

Surgical repair of severe peripheral nerve injuries represents not only a pressing medical need, but also a great clinical challenge. Autologous nerve grafting remains a golden standard for bridging an extended gap in transected nerves. The formidable limitations related to this approach, however, have evoked the development of tissue engineered nerve grafts as a promising alternative to autologous nerve grafts. A tissue engineered nerve graft is typically constructed through a combination of a neural scaffold and a variety of cellular and molecular components. The initial and basic structure of the neural scaffold that serves to provide mechanical guidance and optimal environment for nerve regeneration was a single hollow nerve guidance conduit. Later there have been several improvements to the basic structure, especially introduction of physical fillers into the lumen of a hollow nerve guidance conduit. Up to now, a diverse array of biomaterials, either of natural or of synthetic origin, together with well-defined fabrication techniques, has been employed to prepare neural scaffolds with different structures and properties. Meanwhile different types of support cells and/or growth factors have been incorporated into the neural scaffold, producing unique biochemical effects on nerve regeneration and function restoration. This review attempts to summarize different nerve grafts used for peripheral nerve repair, to highlight various basic components of tissue engineered nerve grafts in terms of their structures, features, and nerve regeneration-promoting actions, and finally to discuss current clinical applications and future perspectives of tissue engineered nerve grafts.

Inferior alveolar nerve injury in implant dentistry: diagnosis, causes, prevention, and management

Inferior alveolar nerve injury is one of the most serious complications in implant dentistry. This nerve injury can occur during local anesthesia, implant osteotomy, or implant placement. Proper understanding of anatomy, surgical procedures, and implant systems and proper treatment planning is the key to reducing such an unpleasant complication. This review discusses the causes of inferior alveolar nerve injury and its diagnosis, prevention, and management.

A bioabsorbable collagen nerve cuff (NeuraGen) for repair of lingual and inferior alveolar nerve injuries: a case series

PURPOSE

This study describes the results of using NeuraGen (Integra LifeSciences, Plainsboro, NJ) as a nerve cuff for repair of lingual and inferior alveolar nerve injuries following third molar surgery.

PATIENTS AND METHODS

Eight female patients received a total of 9 NeuraGen cuffs for repair of lingual (6) or inferior alveolar (3) nerves. All injuries were treated within 3 to 7 months following injury. All patients were evaluated by mechanoceptive and nociceptive testing via brush directional discrimination, pin-prick pressure and thermal sensation. Lateral trap-door osteotomy of the mandible was utilized to access the inferior alveolar nerve. The lingual nerve was approached via a lingual gingival sulcus incision. Following external neurolysis and primary neurorrhaphy, NeuraGen was split longitudinally, and encased the nerve with at least a 1.5 cm margin. One or 2 6-0 prolene horizontal mattress sutures were used to reapproximate the NeuraGen edges and Healon (hyaluronic acid; Advanced Medical Optics, Santa Ana, CA) was applied to the perineural tissues.

RESULTS

Five injuries resulted in objective anesthesia preoperatively with the other 4 having varying degrees of hypoesthesia. Six of the nerve injuries also resulted in dysesthesia. Four patients were followed for at least 1 year and the other 4 patients for about 2.5 years. The most recent data was used for this study. Postsurgical outcome was assessed utilizing some of the criteria proposed by Pogrel to classify patients as having good improvement, some improvement, no improvement, or worsening of symptoms. Four cases were found to have good improvement, 4 with some improvement and 1 had no improvement. None of the cases had worsening of symptoms.

CONCLUSION

While reports of the use of other alloplastic materials for nerve repair were found to be variable, NeuraGen seems to have good preliminary results. Bioresorption is complete which decreases the likelihood of interneural scarring. Also, NeuraGen is not associated with episodes of compression neuropathy reported with other rigid non biodegradable materials. Its use in hand surgery literature and in experimental animal studies showed no statistical significance in outcome when compared to end-to-end anastomosis or nerve grafts. The reported advantage of NeuraGen was the elimination of problems associated with graft harvesting. In this small series, 8 out of 9 nerve repairs showed sensory improvement which suggests a favorable role of NeuraGen as a nerve cuff and protective barrier around the nerve injury site. While primary end-to-end anastomosis has comparable results, a nerve cuff has the advantage of preventing axonal escape at suture lines, it minimizes scar ingrowth and nerve entrapment, and it concentrates growth factors at the injury site.

Platelet rich plasma may enhance peripheral nerve regeneration after cyanoacrylate reanastomosis: a controlled blind study on rats

The aim of this study was to explore the ability of platelet rich plasma (PRP) to promote peripheral nerve regeneration after cyanoacrylate reanastomosis in rats. A total of 18 rats were used in this study. Bilateral sciatic neurotomies were performed in 15 rats, and then immediately reanastomosed with cyanoacrylate glue. On one side (G1), the anastomosed nerves were treated with prepared autologous PRP gel; on the contralateral side (G2) the nerves received no additional treatment. Sham surgery was undertaken on the remaining 3 rats (6 cases) where bilateral sciatic nerves were surgically approached but not cut (passive control group, (G3). Biopsies were harvested 12 weeks postoperatively and examined under the light microscope using osmic acid stain. The number of nerve fibers in the distal and proximal nerve segments of G1 and G2 as well as in G3 were counted and the results analyzed and compared. Animals in G1 and G2 showed some weakness and ulceration in their right and left feet for a few weeks postoperatively, which gradually improved during the follow-up period. The histomorphometric assessment showed a higher axon count in the distal segment of G1 (291.7 axons) compared with that of G2 (280.5 axons) (P=0.001). Similar results were noticed when the proximal segments of both groups were compared (P=0.040). These results were reflected in the values of the neurotization indices of G1 (91.9%) and G2 (89.5%) (P=0.008). The number of nerve fibers in G1 and G2 remained lower than in G3 (P=0.0001). The authors conclude that PRP may enhance the number of regenerating nerve fibers after cyanoacrylate neruoanastomosis.

Autogenous standard versus inside-out vein graft to repair facial nerve in rabbits

OBJECTIVE

To evaluate autogenous vein grafts and inside-out vein grafts as conduits for the defects repair in the rabbit facial nerves.

METHODS

The 10 mm segments of buccal division of facial nerve were transected for 48 rabbits in this study. Then the gaps were immediately repaired by autogenous vein grafts or inside-out vein grafts in different groups. All the animals underwent the whisker movement test and electrophysiologic test during the following 16 weeks at different time points postoperatively. Subsequently, the histological examination was performed to observe the facial nerve regeneration morphologically.

RESULTS

At 8 weeks after operation, the facial nerve regeneration has significant difference between the experimental group and the control group in electrophysiologic test and histological observation. However, at the end of this study, 16 weeks after operation, there was no significant difference between inside-out vein grafts and standard vein grafts in enhancing peripheral nerve regeneration.

CONCLUSION

This study suggest that both kinds of vein grafts play positive roles in facial nerve regeneration after being repaired immediately, but the autogenous inside-out vein grafts might accelerate and facilitate axonal regeneration as compared with control.

Cyanoacrylate glue versus suture in peripheral nerve reanastomosis

OBJECTIVE

To assess the effectiveness of n-butyl-2-cyanoacrylate glue compared with microsuturing technique in peripheral nerve reanastomosis in rats.

STUDY DESIGN

Fourteen young adult white rats were used. Bilateral sciatic neurotomies were performed in 12 of them and then reanastomosed with 3 epineural microsutures in the right side (study group G1) and with n-butyl-2-cyanoacrylate glue in the left side (study group G2). On the remaining 2 rats (control group G3), sham surgery was done on both sides. Biopsies were harvested 12 weeks after surgery and examined under light microscope using Osmic acid stains. The number of nerve fibers was counted in the distal and proximal nerve segments, and the results were analyzed and compared in all groups.

RESULTS

Adequate regeneration with no anastomotic ruptures was seen 12 weeks after surgery in G1 and G2. The histomorphometric assessment showed no statistically significant difference (P = .960) in the neurotization index of G1 (89.01%) compared with G2 (88.97%). There was a significant (P = .001) reduction in the mean number of axon counts distal to the repair in G1 (271.3) and G2 (272.8) compared with that of the proximal segments of each study group (304.6 and 303, respectively, as well as to that of G3 (348.5).

CONCLUSION

Both n-butyl-2-cyanoacrylate adhesive and 3-microsuture techniques showed comparable neurotization indices and were equally adequate to stabilize the nerve during regeneration period.