Facial nerve schwannoma. Curr Opin Otolaryngol Head Neck Surg. 2009;17:346-350. [PMID: 19561500 DOI: 10.1097/moo.0b013e32832ea999]

Schwannomas of Brain and Spinal Cord

Schwannomas are benign tumors originating from the Schwann cells of cranial or spinal nerves. The most common cranial schwannomas originate from the eight cranial nervevestibular schwannomas (VS). VS account for 6-8% of all intracranial tumors, 25-33% of the tumors localized in the posterior cranial fossa, and 80-94% of the tumors in the cerebellopontine angle (CPA). Schwannomas of other cranial nerves/trigeminal, facial, and schwannomas of the lower cranial nerves/are much less frequent. According to the World Health Organization (WHO), intracranial and intraspinal schwannomas are classified as Grade I. Some VS are found incidentally, but most present with hearing loss (95%), tinnitus (63%), disequilibrium (61%), or headache (32%). The neurological symptoms of VSs are mainly due to compression on the surrounding structures, such as the cranial nerves and vessels, or the brainstem. The gold standard for the imaging diagnosis of VS is MRI scan. The optimal management of VSs remains controversial. There are three main management options-conservative treatment or "watch-and-wait" policy, surgical treatment, and radiotherapy in all its variations. Currently, surgery of VS is not merely a life-saving procedure. The functional outcome of surgery and the quality of life become issues of major importance. The most appropriate surgical approach for each patient should be considered according to some criteria including indications, risk-benefit ratio, and prognosis of each patient. The approaches to the CPA and VS removal are generally divided in posterior and lateral. The retrosigmoid suboccipital approach is a safe and simple approach, and it is favored for VS surgery in most neurosurgical centers. Radiosurgery is becoming more and more available nowadays and is established as one of the main treatment modalities in VS management. Radiosurgery (SRS) is performed with either Gamma knife, Cyber knife, or linear accelerator. Larger tumors are being increasingly frequently managed with combined surgery and radiosurgery. The main goal of VS management is preservation of neurological function - facial nerve function, hearing, etc. The reported recurrence rate after microsurgical tumor removal is 0.5-5%. Postoperative follow-up imaging is essential to diagnose any recurrence.

Giant Facial Nerve Schwannoma with Extra-Temporal Involvement: A Series Of Two Cases

Facial nerve schwannoma is a rare benign tumor of temporal bone arising from the schwann cells with incidence of 0.8%. They can arise from any segment of facial nerve with geniculate ganglion being the most common and labyrinthine segment the second commonest site. Intra-temporal location is common while only 9% of the cases have extra-temporal or parotid gland involvement. Bony remodeling or scalloping of the facial canal and the surrounding bone is the classic radiological feature of schwannoma. However schwannomas of temporal bone location can show bony erosions. The management option depends on site, extent, facial nerve function and hearing status. Surgery is reserved for large tumors with poor facial functions, hearing loss and giddiness. Giant facial nerve schwannoma with extra-temporal involvement is a rare entity with only handful number of cases reported in the literature. We present a series of two cases of giant facial nerve schwannoma with parotid gland involvement.

Case Report: Dry Eye Management Leads to Early Diagnosis of Seventh Nerve Schwannoma

SIGNIFICANCE

Facial nerve schwannomas are rare tumors that are usually benign and relatively slow in their progression. Common symptoms include facial neuropathy, auditory deficiencies, and parotid masses. Because of slow progression, symptoms are often present for over a year before an appropriate diagnosis is made.

PURPOSE

The purpose of this study was to present a case in which comprehensive dry eye assessments and management led to diagnosis of facial nerve shwannoma in a patient who had no presenting symptoms of auditory deficiencies or facial weakness.

CASE REPORT

A 36-year-old woman presented for a contact lens examination with concerns of progressively worsening symptoms of irritation and dryness in her right eye that began 6 months earlier. Dry eye assessment visits and management strategies were implemented. Although this regimen was initially successful, symptoms returned after 7 months. At this visit, a new finding of incomplete blink in her right eye was manifested. Further in-office assessments revealed a weakened right orbicularis oculi and right frontalis muscle. These findings, combined with patient risk factors and no history of trauma, prompted MRI of the seventh nerve. Imaging revealed the presence of seventh nerve schwannoma, the location of which correlated with the geniculate ganglion and greater superficial petrosal nerve. This patient was later referred to a neurosurgeon, who assessed the risks and benefits of schwannoma removal. It was decided that the risks of the surgery outweighed the benefits, and regular MRI was scheduled for monitoring purposes. Appropriate management of the patient's chronic dry eye disease continues.

CONCLUSIONS

Facial nerve schwannomas can and do present with no presenting subjective facial neuropathy symptoms aside from mild unilateral dry eye and can be detected with comprehensive dry eye management. This case may contribute to future minor adjustments in clinical practice guidelines for asymmetric dry eye assessments.

Surgical management of intraoperatively diagnosed facial nerve schwannoma located at internal auditory canal and cerebellopontine angle - our experiences of 14 cases

BACKGROUND

Facial nerve schwannomas located at internal auditory canal and cerebellopontine angle (IAC/CPA FNS) were diagnosed intraoperatively, it poses a therapeutic dilemma to the surgeon.

OBJECTIVE

To report our experience in managing IAC/CPA FNS and to propose a treatment strategy.

METHODS

A total of 14 patients with IAC/CPA FNS who were diagnosed intraoperatively and treated by operation between 2015 and 2019 were retrospectively studied.

RESULTS

Unilateral hearing loss was the most common symptom and all these patients had normal facial nerve function preoperatively. Surgical approaches used in these patients including translabyrinthine (2 cases), retrosigmoid (RS) (11 cases), and middle cranial fossa (MCF) approach (1 case). Eight patients underwent partial resection, three patients underwent subtotal resection and three patients had complete tumor removal with facial nerve reconstruction. All partial resection patients and two patients underwent subtotal resection achieved a long-term HB grade I facial nerve function. The long-term facial nerve function of patients underwent complete resection and nerve grafting was no better than HB grade III.1 of the eight patients underwent partial resection experienced tumor regrowth during the follow-up.

CONCLUSIONS

Partial or subtotal resection for IAC/CPA FNS may provide an opportunity of retaining excellent facial nerve function. Regular postoperative imaging is helpful to monitor the recurrence.

Management of intratemporal facial nerve schwannomas: The evolution of treatment paradigms from 2000-2015

Intratemporal facial nerve schwannoma (FNS) are rare benign tumors of the skull base. Many of these tumors will be detected during evaluation for symptoms suggestive of vestibular schwannoma. However, there are several signs and symptoms which can suggest the facial nerve as the origin of the tumor. Intratemporal FNS can be multiple, like “beads on a string”, or solitary lesions of the internal auditory canal. This variable tumor morphology necessitates multiple treatment options to allow patients the best chance of preservation of facial nerve function. Historically FNS were managed with resection of the nerve with cable grafting. However this leaves the patient with permanent facial weakness and asymmetry. Currently most patients find this outcome unacceptable, especially when they present with good to normal facial nerve function. Facial paralysis has a significantly negative impact on quality life, so treatment regimens that spare facial nerve function have been used in patients who present with moderate to good facial nerve function. Nerve sparing options include tumor debulking, decompression of the bony facial canal, radiosurgery, and observation. The choice of management depends on the degree of facial nerve dysfunction at presentation, hearing status in the affected ear, medical comorbidities and patient preference. Each treatment option will be discussed in detail and suggestions for patient management will be presented.

Clinical Retrospective Analysis of 9 Cases of Intraparotid Facial Nerve Schwannoma

PURPOSE

The management of intraparotid facial nerve schwannoma (IFNS) is challenging because it is extremely rare and often misdiagnosed as pleomorphic adenoma or another parotid tumor. The purpose of this study was to report on the authors' experience in the treatment of IFNS and to review the literature regarding the diagnosis and management of IFNS.

MATERIALS AND METHODS

From January 1997 through October 2015, 916 consecutive parotidectomies were performed at Shenzhen People's Hospital (Shenzhen, China). Of 916 parotid tumors samples, 9 cases of IFNS confirmed by histopathology were identified and analyzed retrospectively. In addition, 161 published cases from 1956 through 2015 were systematically reviewed.

RESULTS

Nine cases of IFNS were identified from 916 parotid tumors samples and accounted for 0.98% of all parotid tumors. All these patients with IFNS underwent tumor removal and parotidectomy with preservation of facial nerve (FN) continuity. The mean follow-up period was 6.2 years (range, 1 to 16 yr). Facial function improved gradually from House-Brackmann grade (HBG) II to III immediately postoperatively to HBG I during the subsequent 3 to 9 months in all cases. Tumor recurrence with stylomastoid foramen involvement was observed in 1 case 3 years after surgery. The others remained free of recurrence. Of 161 IFNS cases reported in the literature, 17 cases with facial paresis were found to have intra-temporal involvement, but no facial paresis was found in patients with intraparotid involvement only.

CONCLUSIONS

An IFNS is easily misdiagnosed as pleomorphic adenoma or Warthin tumor preoperatively; the correct diagnosis for IFNS depends mainly on intraoperative observation of the gross relation between the tumor and the FN or excision frozen biopsy examination. The integrity of the FN should be preserved for patients with IFNS and without facial paresis, whenever possible.

Intraoperatively diagnosed cerebellopontine angle facial nerve schwannoma: how to deal with it

OBJECTIVE

This study aimed to report our experience in the management of patients with intraoperatively diagnosed intracranial facial nerve schwannomas (FNSs) and propose a decision-making strategy.

METHODS

Twenty-three patients with FNS of the internal auditory canal and/or cerebellopontine angle operated on between 1992 and 2012 were identified.

RESULTS

Preoperatively, all cases have been radiographically diagnosed as vestibular schwannomas. Operative procedures consisted of total tumor resection with grafting in 43.4% of patients, near-total resection leaving behind the tumor capsule overlying the facial nerve in 21.7%, total tumor resection with preservation of anatomic continuity of the facial nerve in 13%, and subtotal resection in 4.3%. Four patients (17.4%) underwent bony decompression with no tumor removal.

CONCLUSION

Management of FNS diagnosed at surgery represents a significant clinical challenge. We considered total tumor resection with grafting when patients presented with preoperative facial nerve palsy (≥ grade III). Both subtotal and near-total tumor removal can be performed in patients with preoperative good facial function and/or large tumors with brainstem compression. Patients with small tumors who were selected for hearing preservation surgery can be considered for bony decompression. Fascicle preservation surgery may be an option when a clear cleavage plane between the tumor and the facial nerve is found.

Facial Schwannomas: Various Presentations and their Management with Literature Review

Facial schwannomas or neuromas are rare entity. They often are confused with vestibular schwannomas on imaging, especially if they are limited to the cisternal segment of the facial nerve. Awareness regarding this entity is paramount for the early diagnosis and correct management which may differ from patient to patient. We share the different clinical presentations of this rare benign tumour and discuss their management strategies in light of the affected segment of the nerve. The results were analyzed along with review of literature. Three cases of facial schwannomas were analyzed retrospectively during last 4 years and their presentation, imaging, preferred surgical approaches, intra-operative findings and post grafting results are discussed. All three patients underwent surgical excision with sural nerve cable grafting and have no recurrence till date. However, the facial paresis remained the same in one of the cases while improvement was observed in two patients. The improvement was delayed in one patient as documented by electromyography of facial muscles. Facial schwannomas are slow growing tumours with low incidence. Usual presentations can sometimes be masked. Appropriate management decision needs to be arrived after considering three determinants i.e. the patient's age, hearing status and the severity of facial paresis (House-Brackmann grading). Nerve reconstruction after excision should be performed in each case and sometimes the results may be delayed. It is thus important to keep a close surviellance during the follow up and to perform the electrophysiological tests frequently so as to detect the earliest signs of regeneration (which can be delayed up to 18 months).

Are the current treatment strategies for facial nerve schwannoma appropriate also for complex cases?

OBJECTIVES

To describe the decision-making strategies for complex facial nerve schwannomas (FNSs).

MATERIALS AND METHODS

Charts belonging to 103 consecutive patients with facial nerve tumors managed between 1990 and 2011 were examined retrospectively to identify complex FNSs. To be classified as complex, at least one of the following criteria had to be met: (1) FNS with large intraparotid tumor component and preoperative good facial nerve function (3 cases); (2) multiple-segment FNSs with extension to both the cerebellopontine angle and the middle cranial fossa in patients with preoperative good hearing (5 cases); (3) fast-growing FNS with preoperative good facial nerve function (4 cases), and (4) large FNS compressing the temporal lobe with preoperative normal facial nerve function (1 case).

RESULTS

Thirteen patients were classified as complex; 12 patients had total tumor removal with sural nerve grafting and 1 patient had partial tumor removal. Two patients with intratemporal-intraparotid FNS underwent a transmastoid-transparotid approach. One patient with a tumor extending from the geniculate ganglion to the parotid portion of the facial nerve underwent a combined middle fossa transmastoid-transparotid approach. A transcochlear approach with temporal craniotomy was performed in all the patients with multiple-segment FNS as well as in patients with fast-growing tumors extending both in the cerebellopontine angle and middle cranial fossa. A partial tumor removal through the middle fossa approach was performed in 1 patient with a large tumor compressing the temporal lobe.

CONCLUSIONS

Therapeutic options for patients with FNS include surgical intervention, observation and radiotherapy. Nowadays, surgical resection with facial nerve repair is usually the standard management for patients with poor facial function (House-Brackmann grade III or worse). In patients presenting with normal or near-normal facial nerve function, initial observation with periodic examination and imaging is usually recommended. However, on rare occasions surgeons can be faced with a situation in which the management decision-making process is particularly challenging. In these complex cases treatment should be individualized. We recommend early surgical intervention regardless of the preoperative facial and hearing functions in the following cases: intratemporal FNSs extending with a large tumor component into the parotid, multiple-segment FNSs extending in both the cerebellopontine angle and the middle cranial fossa, fast-growing FNSs, and large FNSs with temporal lobe compression.

Management Outcomes of Facial Nerve Tumors

Objectives

Primary facial nerve tumors (FNTs) present in varying ways. In this study, the authors present their institutional experience with the management of facial nerve tumors, including their recommendations for available therapies such as observation, microsurgical decompression or removal, and stereotactic radiation. They emphasize the auditory and facial nerve function outcomes.

Study Design

Retrospective case review.

Setting

Tertiary referral center.

Subjects and Methods

Retrospective review of all cases of FNT seen at the authors’ tertiary care academic medical center over a 10-year period (2002-2011). The clinical presentation, treatment modality, and outcome parameters of cochlear and facial nerve function were assessed.

Results

Twelve patients were identified. House-Brackmann grades on presentation were 4 grade I, 2 grade II, 2 grade III, 1 grade IV, and 3 grade V, with 2 grade V patients declining to grade VI shortly after presentation. Seven patients presented with serviceable hearing and 4 with nonserviceable hearing. Treatment options/arms included observation with serial clinicoradiological review (2 cases), stereotactic radiation with the CyberKnife (3 cases), wide fallopian canal decompression (3 cases), microsurgical excision and repair (3 cases), and biopsy followed by observation (1 case). At the end of the review period, facial nerve function was stable in 8 patients, improved in 3, and declined in 1, and none had documented worsening of hearing based on American Academy of Otolaryngology—Head and Neck Surgery Foundation classification.

Conclusions

Management of FNT is largely based on the clinicoradiological picture. Each treatment arm is different, but overall auditory and facial function can be maintained.