Primary tumors of the facial nerve

Task force of the Brazilian Society of Otology - evaluation and management of peripheral facial palsy

OBJECTIVE

To review key evidence-based recommendations for the diagnosis and treatment of peripheral facial palsy in children and adults.

METHODS

Task force members were educated on knowledge synthesis methods, including electronic database search, review and selection of relevant citations, and critical appraisal of selected studies. Articles written in English or Portuguese on peripheral facial palsy were eligible for inclusion. The American College of Physicians' guideline grading system and the American Thyroid Association's guideline criteria were used for critical appraisal of evidence and recommendations for therapeutic interventions.

RESULTS

The topics were divided into 2 main parts: (1) Evaluation and diagnosis of facial palsy: electrophysiologic tests, idiopathic facial palsy, Ramsay Hunt syndrome, traumatic peripheral facial palsy, recurrent peripheral facial palsy, facial nerve tumors, and peripheral facial palsy in children; and (2) Rehabilitation procedures: surgical decompression of the facial nerve, facial nerve grafting, surgical treatment of long-term peripheral facial palsy, and non-surgical rehabilitation of the facial nerve.

CONCLUSIONS

Peripheral facial palsy is a condition of diverse etiology. Treatment should be individualized according to the cause of facial nerve dysfunction, but the literature presents better evidence-based recommendations for systemic corticosteroid therapy.

Characteristics and Management of Facial Nerve Schwannomas and Hemangiomas

OBJECTIVES

To characterize facial nerve (FN) schwannomas (FNSs) and FN hemangiomas (FNHs) and their clinical features and management strategies, and to describe the results of cable nerve grafting after FN sectioning during tumor removal.

METHODS

This retrospective study included 84 FNS cases and 42 FNH cases managed between July 1989 and July 2020 at a quaternary referral center for skull base pathology. Clinical details, locations, management, and results of cable nerve grafting at 1 year and during an average period of 3.12 years were evaluated. Sural nerve interpositioning was performed for patients who experienced FN paralysis for less than 1 year and underwent nerve sectioning during tumor removal.

RESULTS

FNSs more often involved multiple segments compared with FNHs. The cerebellopontine angle and the mastoid segments were involved in 16 (19.1%) and 34 (40.5%) FNS cases, respectively; however, the cerebellopontine angle and the mastoid segments were involved in 0 and 7 (16.7%) FNH cases, respectively. Sectioned nerves of 99 patients (78.6%) were restored using interposition cable grafting. At the last follow-up evaluation, 56.3% of FNSs and 60.7% of FNHs attained House-Brackmann (HB) grade III. Lower preoperative HB grades were associated with poorer postoperative outcomes. For FNSs, the mean HB grades were 4.13 at 1 year postoperatively and 3.75 at the last follow-up evaluation ( p = 0.001); however, for FNHs, the mean HB grades were 4.04 postoperatively and 3.75 at the last follow-up evaluation. Therefore, extradural coaptation yielded better outcomes.

CONCLUSION

FNSs can occur along any part of the FN along its course, and FNHs are concentrated around the area of geniculate ganglion. The results of cable inter positioning grafts are better in patients with preoperative FN-HB-III or less when compared with higher grades. The outcome of the interpositioning continues to improve even after 1 year in extradural coaptation.

Facial nerve schwannoma and other benign neoplastic facial nerve lesions

PURPOSE OF REVIEW

Several neoplastic lesions may originate from facial nerves, including facial nerve schwannomas. These neoplastic lesions can cause various symptoms, such as facial nerve paralysis, and decrease the quality of life of patients. Therefore, knowledge of how to manage these diseases is important for otologists. However, the incidence of these diseases is extremely low, and universal management methods have not yet been established. This review summarizes recent advances in knowledge regarding these neoplastic lesions, especially facial nerve schwannomas.

RECENT FINDINGS

Recent advances and the accumulation of knowledge regarding these benign facial nerve lesions have provided several preferable treatments and management methods, especially for facial nerve schwannomas. However, this still depends on the patient's symptoms and tumor localization.

SUMMARY

This review presents the optimal treatment protocol and differential diagnosis of benign facial nerve lesions. This may be useful for pretreatment differentiation and treatment decision-making.

Facial nerve in skullbase tumors: imaging and clinical relevance

Facial nerve, the 7th cranial nerve, is a mixed nerve composed of sensory and motor fibers, and its main branch is situated in the cerebellopontine angle. Facial nerve dysfunction is a debilitating phenomenon that can occur in skullbase tumors and Bell's pals. Recovery of the facial nerve dysfunction after surgery for skullbase tumors can be disappointing, but is usually favorable in Bell's palsy. Advances in magnetic resonance imaging (MRI) allow to visualize the facial nerve and its course in the cerebellopontine angle, also when a large tumor is present and compresses the nerve. Here, we describe the anatomical, neurochemical and clinical aspects of the facial nerve and highlight the recent progress in visualizing the facial nerve with MRI.

Oliveira F, Lavinsky J, Isolan G. Facial Nerve Hemangioma of the Lateral Portion of the Internal Acoustic Canal: A Case Report and a Review of Literature

Introduction  Facial nerve hemangiomas (FNH) are rare tumors. Although it can occur in any portion of the nerve, it predominantly appears near the geniculate ganglion. We present a case of facial nerve hemangioma of an unusual location. Case Report  A 30-year-old woman presented with right-sided severe hearing loss and progressive facial palsy. Magnetic resonance showed a 5 mm lesion in the lateral portion of the right internal auditory canal. Due to facial palsy, the patient was submitted to a translabyrinthine approach and a total tumor resection, followed by hypoglossal-facial nerve anastomosis. Discussion  The facial nerve is susceptible in its path to expansive lesions, which have high morbidity. FNH is a rare and difficult-to-diagnose lesion. Computerized tomography and nuclear magnetic resonance can be used in its diagnosis. The differential diagnosis of FNH includes, in addition to schwannomas, meningiomas, cholesteatomas, paragangliomas, and other temporal bone tumors. There is no well-established consensus on the best approach. Because of its slow growth and benign behavior, some studies suggest conservative treatment and serial imaging. However, surgery is the cornerstone of treatment, as it is the only curative option. Conclusion  FNHs are often small but very symptomatic. Its high morbidity demands early diagnosis and, sometimes, surgical treatment.

Features of postoperative hearing function changes in patients with cerebellopontine angle and intratemporal tumors other than vestibular schwannomas

OBJECTIVE

Tumors around the cerebellopontine angle (CPA) and temporal bone can potentially affect hearing function. In patients with such tumors other than vestibular schwannomas (VSs), auditory tests were investigated before and after surgery to characterize the auditory effect of each tumor and to determine prognostic factors.

METHODS

A total of 378 patients were retrospectively evaluated for hearing functions before and after surgery. These 378 patients included 168 with CPA meningioma, 40 with trigeminal schwannoma (TS), 55 with facial nerve schwannoma (FNS), 64 with jugular foramen schwannoma (JFS), and 51 with CPA epidermoid cyst (EPD).

RESULTS

Preoperative hearing loss was observed in 124 (33%) of the 378 patients. Of these 124 patients, 38 (31%) experienced postoperative hearing improvement. Postoperative hearing deterioration occurred in 67 (18%) of the 378 patients. The prognostic factors for postoperative hearing improvement were younger age and the retrocochlear type of preoperative hearing disturbance. Tumor extension into the internal auditory canal was correlated with preoperative hearing loss and postoperative hearing deterioration. Preoperative hearing loss was observed in patients with FNS (51%), JFS (42%), and MGM (37%), and postoperative hearing improvement was observed in patients with JFS (41%), MGM (31%), and FNS (21%). Postoperative hearing deterioration was observed in patients with FNS (27%), MGM (23%), and EPD (16%).

CONCLUSIONS

According to the results of this study in patients with CPA and intratemporal tumors other than VS, preoperative retrocochlear hearing disturbance was found to be a prognostic factor for hearing improvement after surgery. Among the tumor types, JFS and MGM had a particularly favorable hearing prognosis. The translabyrinthine approach and cochlear nerve section should be avoided for these tumors, regardless of the patient's preoperative hearing level.

Intratemporal Facial Nerve Schwannomas: A Review of 45 Cases in A Single Center

There are no established indications for facial nerve schwannoma treatment, including surgery, radiation and follow-up observation, and it is difficult to determine treatment policy uniformly. The treatment policy was examined from each treatment course. Data of patients with facial nerve schwannomas at our hospital from 1987 to 2018 were retrospectively examined. Their age, sex, clinical symptoms, tumor localization, treatment policies and outcomes were reviewed. In total, 22 patients underwent surgery and 1 patient underwent radiotherapy; 22 patients were followed up without treatment. After total resection, there were no tumor recurrences, and most patients had grade 3 or 4 postoperative facial paralysis. After subtotal resection, tumor regrowth was observed in four patients and reoperation was required in two patients. Facial nerve function was maintained in four patients and was decreased in two patients. During follow-up, six patients showed tumor growth. Only one patient had worsening facial nerve paralysis; four patients underwent facial nerve decompression owing to facial nerve paralysis during follow-up. If the tumor compresses the brain or it is prone to growth, surgery may be indicated, and when the preoperative facial nerve function is grade ≤ 3, consideration should be given to preserving facial nerve function and subtotal resection should be indicated. If the preoperative facial nerve function is grade ≥ 3, total resection with nerve grafting is an option to prevent regrowth. If there is no brain compression or tumor growth, the follow-up is a good indication, and decompression should be considered in facial nerve paralysis cases.

Management of non-vestibular schwannomas in adult patients: a systematic review and consensus statement on behalf of the EANS skull base section Part II: Trigeminal and facial nerve schwannomas (CN V, VII)

BACKGROUND

Non-vestibular schwannomas are relatively rare, with trigeminal and jugular foramen schwannomas being the most common. This is a heterogenous group which requires detailed investigation and careful consideration to management strategy. The optimal management for these tumours remains unclear and there are several controversies. The aim of this paper is to provide insight into the main principles defining management and surgical strategy, in order to formulate a series of recommendations.

METHODS

A task force was created by the EANS skull base section committee along with its members and other renowned experts in the field to generate recommendations for the surgical management of these tumours on a European perspective. To achieve this, the task force performed an extensive systematic review in this field and had discussions within the group. This article is the second of a three-part series describing non-vestibular schwannomas (V, VII).

RESULTS

A summary of literature evidence was proposed after discussion within the EANS skull base section. The constituted task force dealt with the practice patterns that exist with respect to pre-operative radiological investigations, ophthalmological assessments, optimal surgical and radiotherapy strategies, and follow-up management.

CONCLUSION

This article represents the consensually derived opinion of the task force with respect to the treatment of trigeminal and facial schwannoma. The aim of treatment is maximal safe resection with preservation of function. Careful thought is required to select the appropriate surgical approach. Most middle fossa trigeminal schwannoma tumours can be safely accessed by a subtemporal extradural middle fossa approach. The treatment of facial nerve schwannoma remains controversial.

[Clinical analysis of 32 cases of facial nerve schwannomas]

Objective:To elucidate the clinical characteristics, surgical strategy, facial nerve repair methods and outcomes of facial nerve schwannomas（FNS）. Methods:The clinical data of patients with FNS treated between January 2010 and December 2018 at Sun Yat-sen Memorial Hospital of Sun Yat-sen University were retrospectively collected, including the sidedness of FNS, clinical manifestations, imaging data, the extent of tumor, clinical management, preoperative and postoperative facial nerve function. Results:The major clinical manifestations of the 32 patients with FNS were facial palsy（27, 84.4%）, hearing loss（27, 84.4%）, tinnitus（22, 68.8%）, ear mass（15, 46.9%）, and stuffy feeling in the ear（13, 40.6%） respectively. Thirty patients were preoperatively diagnosed with FNS and 2 patients were misdiagnosed. 31 patients underwent resection of FNS, except one patient who was selected for long-term follow-up observation. The choice of surgical approach was based on the location, extent and auditory function of the FNS involved as well as the patient's wishes. The surgical approach was decided based on the location and extent of the tumor: 9 patients were operated via the inferior temporal fossa type A（Fisch A） approach; 8 patients were operated via the mastoid approach; 7 patients were operated via the enlarged mastoid approach; 3 patients were operated via the combined mastoid-cranial middle fossa approach; 1 patient was operated via the cranial middle fossa approach; 3 patients were operated via the combined Fisch A-cranial middle fossa approach. 28 patients（87.5%） had FNS with multiple segments of facial nerve involved. The most involved segment was the vertical segment of the facial nerve（26, 81.3%）. 15 patients underwent facial nerve repair simultaneously, including 7 cases of auricular nerve-facial nerve graft and 8 cases of facial nerve-sublingual nerve anastomosis. 4 cases had improved facial nerve function after auricular nerve-facial nerve graft and 2 cases had improved function after facial nerve-sublingual nerve anastomosis. Among patients who underwent facial nerve repair,the best outcome was H-B Ⅲ. Conclusion:The patients with FNS mainly presented with facial palsy and hearing loss. Temporal bone CT and cranial MR plain & enhanced scan served well to confirm the diagnosis. The improvement rate of postoperative facial nerve function was significantly higher in patients who underwent nerve repair than in those who did not. Hence, facial nerve repair should be considered. Compared with facial nerve-sublingual nerve anastomosis, auricular major nerve-facial nerve graft might be a better choice for improving postoperative facial nerve function.

Rare Diseases of the Salivary Glands and of Facial Nerve

Salivary gland diseases are rare. In the European Union (EU) a disease is considered to be rare if not more than 5 of 10,000 people are affected by it. According to estimates in Germany are about 4 million people with a rare disease. In the EU are about 30 million people with rare diseases [1]. In the present work most of the described diseases of salivary glands and of the facial nerve fall in this category. They form a very heterogeneous group whose treatment takes place mainly in specialized centers. Still, it is essential for the otolaryngologist to identify and to diagnose these diseases in order to initiate the right therapeutic steps. The work is a compilation of innate andacquired rare salivary gland disorders and of rare facial nerve disorders. The etiologies of inflammatory diseases, autoimmune disorders and tumors are taken into account. For the individual topics, the current literature, if available, was evaluated and turned into summarized facts. In this context the development of new processes, diagnostics, imaging and therapy are considered. Genetic backgrounds of salivary gland tumors and the trends in the treatment of tumorous lesions of the facial nerve are picked up. Furthermore, also rare diseases of the salivary glands in childhood are described. Some of them can occur in adults as well, but differ in frequency and symptoms. Due to the rarity of these diseases, it is recommended to tread these in centers with special expertise for it. Finally, the difficulties of initiation of studies and the problems of establishing disease registries concerning salivary gland disorders are discussed. This is very relevant because these pathologies are comparatively seldom.

Unilateral Facial Paralysis in the Pediatric Patient

Unilateral facial paralysis (FP) in the pediatric population is a rare entity secondary to multiple etiologies including infectious, vascular, and neoplastic. In persistent or recurrent FP, imaging can demonstrate a peripheral facial nerve (FN) lesion. Given the rarity of FN lesions, however, there is limited literature regarding optimal management. In this case series, we describe the presentation, evaluation, and management of unilateral FP in three pediatric patients along with a review of the literature. All patients presented with complete FP due to a peripheral FN lesion or compression of the FN. A combined mastoid and middle cranial fossa approach was utilized for excision in two cases, and the other child underwent a translabyrinthine approach. The pathology of the lesions revealed a meningioma, an arachnoid cyst, and a hemangioma. Presentation, evaluation, post-operative outcomes, as well as final pathologies are discussed.

Primary facial nerve paraganglioma: report and review of the literature

This report describes the diagnosis and treatment of a patient with a rare primary facial nerve paraganglioma as well as a review of the current literature. A 60-year-old male patient presented to our clinic with a 4-month history of left-sided progressive facial paralysis House-Brackmann V. Biopsy taken during facial nerve (FN) decompression confirmed the diagnosis of paraganglioma. The left FN was sacrificed during resection of the mass and a 12-7 jump graft, using the left greater auricular nerve, was performed with acceptable outcomes. The rarity of these tumours does not discount their clinical importance or the necessity to include them in the differential when presented with unilateral FN paralysis. Investigation should begin with CT and MRI imaging to identify and localise the potential mass. Histologic confirmation requires tissue. While surveillance imaging is occasionally an option, often complete surgical resection of the mass and sacrifice of the nerve is necessary.

The paralyzing legal costs of facial nerve injury in head and neck tumors

PURPOSE

Facial nerve paralysis from head and neck tumors can result from disease progression or iatrogenic causes, leading to litigation. The aim of this study was to investigate lawsuits regarding facial paralysis as a consequence of these tumors to understand and better educate physicians behind the reasons for litigation.

METHODS

Jury verdict reviews were obtained from the Westlaw database from 1985 to 2018. Gathered data, including verdicts, litigation reasons, defendant specialties, and amounts awarded, were analyzed via Statistical Package for the Social Sciences.

RESULTS

Of the 26 lawsuits analyzed, the leading reason for litigation was failure to diagnose (53.8%), followed by iatrogenic injury (34.6%). The average award was $2,704,470. Otolaryngologists were the most common defendants. Defendants that included an otolaryngologist had shorter delays of diagnosis compared to those that did not (p < 0.05).

CONCLUSION

Failure to diagnose parotid injury was the leading cause of litigation. In instances where the jury found for the plaintiff, the amount was material. There were equivalent incidences of cases in favor of plaintiffs and defendants.

Facial Schwannoma Management Outcomes: A Systematic Review of the Literature

OBJECTIVE

To evaluate facial nerve outcomes of various management strategies for facial schwannomas by assimilating individualized patient data from the literature to address controversies in management.

DATA SOURCES

PubMed-National Center for Biotechnology Information and Scopus databases.

REVIEW METHODS

A systematic review of the literature was performed for studies regarding facial schwannomas. Studies were included if they presented patient-level data, type of intervention, pre- and postintervention House-Brackmann (HB) grades, and tumor location by facial nerve segment.

RESULTS

Individualized data from 487 patients were collected from 31 studies. Eighty (16.4%) facial schwannomas were managed with observation, 25 (5.1%) with surgical decompression, 20 (4.1%) with stereotactic radiosurgery, 225 (46.2%) with total resection, and 137 (28.1%) with subtotal resection/stripping surgery. Stripping surgery/subtotal resection with good preoperative facial nerve function maintained HB grade 1 or 2 in 96% of cases. With a total resection of intradural tumors, preoperative HB grade did not significantly affect facial nerve outcome (n = 45, P = .46). However, a lower preoperative HB grade was associated with a better facial nerve outcome with intratemporal tumors (n = 56, P = .009). When stereotactic radiosurgery was performed, 40% of patients had improved, 35% were stable, and 25% had worsened facial function. Facial nerve decompression rarely affected short-term facial nerve status.

CONCLUSION

The data from this study help delineate which treatment strategies are best in which clinical scenarios. The findings can be used to develop a more definitive management algorithm for this complicated pathology.

Primary temporal bone chondrosarcoma: experience with 10 cases

Background: Temporal bone chondrosarcoma (TBC) are uncommon primary temporal bone malignancies, and clinicians lack experience in its diagnosis and treatment. The optimal management of patients with tumor of TBC also remains a topic of debate and controversy. Objectives: This article summarizes the experience of diagnosis and treatment of TBC, in order to improve the quality of life of cancer patients in the future. Material and methods: We conducted a retrospective analysis of 10 patients who were referred to our hospital from June 2009 to June 2018 for the treatment of TBC. Results: There were 3 males and 7 females. The most common presenting symptoms were facial paresis (50%) and hearing loss (40%), whereas otalgia (10%), vertigo (10%) and headache (10%) were less common. All tumors originated from the temporal bone, and 80% involved the jugular foramen area. All patients survived without evidence of disease at a median time of follow up of 28.8 months. Conclusions and significance: TBC mostly originated in the middle ear mastoid area, and easily extended to the jugular foramen area. An individualized surgical procedure that removes tumors integrally with minimal nerve and blood vessel damage provides long-term cancer control and minimal morbidity in most cases.

The Natural History of Facial Schwannomas: A Meta-Analysis of Case Series

Objective  This study is to establish predictors of facial paralysis and auditory morbidity secondary to facial schwannomas by assimilating individualized patient data from the literature. Design  A systematic review of the literature was conducted for studies regarding facial schwannomas. Studies were only included if they presented patient level data, House-Brackmann grades, and tumor location by facial nerve segment. Odds ratios (OR) were estimated using generalized linear mixed models. Main Outcome Measures  Facial weakness and hearing loss. Results  Data from 504 patients were collected from 32 studies. The geniculate ganglion was the most common facial nerve segment involved (39.3%). A greater number of facial nerve segments involved was positively associated with both facial weakness and hearing loss, whereas tumor diameter did not correlate with either morbidity. Intratemporal involvement was associated with higher odds of facial weakness (OR = 4.78, p  < 0.001), intradural involvement was negatively associated with facial weakness (OR = 0.56, p  = 0.004), and extratemporal involvement was not a predictor of facial weakness (OR = 0.68, p  = 0.27). The odds of hearing loss increased with more proximal location of the tumor (intradural: OR = 3.26, p  < 0.001; intratemporal: OR = 0.60, p  = 0.14; extratemporal: OR = 0.27, p  = 0.01). Conclusion  The most important factors associated with facial weakness and hearing loss are tumor location and the number of facial nerve segments involved. An understanding of the factors that contribute most heavily to the natural morbidity can help guide the appropriate timing and type of intervention in future cases of facial schwannoma.

Anatomy and Surgical Approach of the Ear and Temporal Bone

The temporal bone is one of the more complex structures at the skull base that houses the hearing and vestibular organs, numerous nerves, and vessels. A host of inflammatory and neoplastic processes can occur within the temporal bone that often necessitate permanent and frozen section pathologic examination. A number of simple to complex surgical procedures are used to manage temporal bone pathology. This chapter will provide a brief overview of normal temporal bone anatomy, common surgical approaches, normal histology, and indications for pathologic examination.

Case analysis of temporal bone lesions with facial paralysis as main manifestation and literature review

OBJECTIVE

This study aims to discuss clinical characteristics, image manifestation and treatment methods of temporal bone lesions with facial paralysis as the main manifestation for deepening the understanding of such type of lesions and reducing erroneous and missed diagnosis.

METHODS

The clinical data of 16 patients with temporal bone lesions and facial paralysis as main manifestation, who were diagnosed and treated from 2009 to 2016, were retrospectively analyzed. Among these patients, six patients had congenital petrous bone cholesteatoma (PBC), nine patients had facial nerve schwannoma, and one patient had facial nerve hemangioma. All the patients had an experience of long-term erroneous diagnosis.

RESULTS

The lesions were completely excised by surgery. PBC and primary facial nerve tumors were pathologically confirmed. Facial-hypoglossal nerve anastomosis was performed on two patients. HB grade VI was recovered to HB grade V in one patient. The anastomosis failed due to severe facial nerve fibrosis in one patient. Hence, HB remained at grade VI. Postoperative recovery was good for all patients. No lesion recurrence was observed after 1-6 years of follow-up.

CONCLUSION

For the patients with progressive or complete facial paralysis, imaging examination should be perfected in a timely manner. Furthermore, PBC, primary facial nerve tumors and other temporal bone space-occupying lesions should be eliminated. Lesions should be timely detected and proper intervention should be conducted, in order to reduce operation difficulty and complications, and increase the opportunity of facial nerve function reconstruction.

Surgical Management of Intrinsic Tumors of the Facial Nerve

BACKGROUND

Intrinsic tumors of the facial nerve are a rare entity. Dealing with this subset of tumors is challenging both in terms of decision making and surgical intervention.

OBJECTIVE

To review the outcomes of surgical management of facial nerve tumors and cable nerve graft interpositioning.

METHODS

A retrospective analysis was performed at a referral center for skull base pathology. One hundred fifteen patients who were surgically treated for facial nerve tumors were included. In case of nerve interruption during surgery, the cable nerve interpositioning technique was employed wherein the facial nerve palsy lasted for less than 1-yr duration. In cases of facial nerve palsy lasting for greater than 1 yr, the nerve was restituted by a hypoglossal facial coaptation.

RESULTS

Various degrees of progressive paralysis were seen in 84 (73%) cases. Sixty nine (60%) of the tumors involved multiple segments of the facial nerve. Sixty-two (53.9%) tumors involved the geniculate ganglion. Seventy four (64.3%) of the cases were schwannomas. Hearing preservation surgeries were performed in 60 (52.1%). Ninety one (79.1%) of the nerves that were sectioned in association with tumor removal were restituted primarily by interposition cable grafting. The mean preoperative House-Brackmann grading of the facial nerve was 3.6. The mean immediate postoperative grading was 5.4, which recovered to a mean of 3.4 at the end of 1 yr.

CONCLUSION

In patients with good facial nerve function (House-Brackmann grade I-II), a wait-and-scan approach is recommended. In cases where the facial nerve has been interrupted during surgery, the cable nerve interpositioning technique is a convenient and well-accepted procedure for immediate restitution of the nerve.