Intracranial Facial Nerve Schwannomas: Current Management and Review of Literature

Surgical Outcomes in Patients with Endolymphatic Sac Tumors: A Single-Center Experience of 29 Patients

OBJECTIVE

To analyze the clinical features and surgical outcomes of patients with endolymphatic sac tumors (ELSTs).

STUDY DESIGN

Single institution retrospective cohort study.

METHODS

The clinical data of 29 patients with 30 ELSTs who underwent surgery were retrospectively reviewed. Information on patient demographics, tumor size and grade, intraoperative blood loss volume, hearing and facial nerve outcomes, and follow-up data was collected and analyzed.

RESULTS

The main symptoms were hearing loss in 26 ELSTs (86.7%) and tinnitus in 17 (56.7%). Twenty-four (80%) ELSTs were in advanced stages (Grade III). The median tumor volume was 6.35 cm3. The median intraoperative blood loss volume was 300 mL. Facial nerve function was well preserved in 21 patients. Among all patients with Grade III tumors, 12 patients underwent tension-free anterior facial nerve rerouting, and 11 patients (91.7%) maintained good facial nerve function postoperatively (HB I and HB II). Only one patient exhibited permanent vocal cord paralysis, and no patients experienced cerebrospinal fluid (CSF) leakage postoperatively. Gross total resection was achieved in 22 patients (73.3%), 5 patients (16.7%) experienced tumor recurrence, and 3 (10%) had residual tumors.

CONCLUSIONS

Most ELSTs tend to be diagnosed in the advanced stage. Tension-free anterior facial nerve rerouting could maximally preserve facial nerve function. The intraoperative blood loss volume was associated with tumor size and stage. Tumor recurrence tends to occur at the posterior edge of the petrosal bone, internal auditory canal, and surface of the posterior fossa. Given the relatively high recurrence rate of ELSTs, long-term follow-up is recommended.

LEVEL OF EVIDENCE

4 Laryngoscope, 2024.

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.

Accessory nerve schwannoma extending into the fourth ventricle: case report and review of literature

Accessory nerve schwannoma is a rare entity in patients presenting with cranial nerve (CN) deficits. Most of these tumours arise from the cisternal segment of the eleventh CN and extend caudally. Herein, we report the third case of an accessory schwannoma extending cranially into the fourth ventricle. A 61-year-old female presented with a history of variable headaches. Cerebral magnetic resonance imaging (cMRI) revealed a large inhomogeneous contrast-enhancing lesion at the craniocervical junction extending through the foramen of Magendi and concomitant hydrocephalus due to obstruction of the foramina of Luschkae. Microsurgical tumour resection was performed in the half-sitting position. Intraoperatively, the tumour arose from a vestigial fascicle of the spinal accessory nerve. At three month follow-up, neither radiological tumour recurrence nor neurological deficits were observed.

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.

Orbital schwannoma management: a case report, literature review, and potential paradigm shift

PURPOSE

To present a case of orbital schwannoma and assess the literature on treatment modalities.

METHODS

A MEDLINE literature search for cases of orbital schwannomas was performed using the PubMed search tool using the search terms "orbital schwannoma" and "orbital neurilemmoma." Papers were included if they were peer-reviewed, published in English, discussed management, and included the search terms. Each article was rated using the scale developed by the British Centre for Evidence-Based Medicine. In addition, we present a case report of an orbital schwannoma.

RESULTS

A total of 428 articles were found. 102 met the criteria for inclusion. Only two articles met Level 1 evidence and 16 were important to the clinical care process. We report a case of a biopsy-proven orbital schwannoma managed conservatively with observation over a 4-year period due to risk of cosmetic disfigurement with tumor removal. There has been no change in tumor size and no associated complications during follow up.

CONCLUSIONS

There is a paucity of data on the natural history of orbital schwannomas. Based on our review of the literature, we recommend observation for asymptomatic or minimally symptomatic orbital schwannomas with minimal growth over an extended period of time. For rapidly growing tumors or large tumors affecting key structures causing visual loss, diplopia, aesthetic disfigurement, or patient discomfort, a more aggressive approach may be necessary.

[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.

Preoperative Differences in Intracranial Facial Versus Vestibular Schwannomas: A Four Nerve Assessment

OBJECTIVES

Assesses whether preoperative functional testing can distinguish vestibular schwannomas from facial nerve schwannomas medial to the labyrinthine segment.

STUDY DESIGN

Retrospective cohort.

METHODS

Retrospectively review surgically managed intracranial facial and vestibular schwannomas between January 2015 and December 2019 at two tertiary care centers. Patients with neurofibromatosis 2 and surgery for recurrence were excluded. Preoperative functional testing to include House-Brackmann scores, electroneuronography (ENoG), cervical vestibular evoked myogenic potentials (cVEMP), caloric testing, acoustic brainstem responses (ABRs), acoustic reflexes, and audiograms was compared between the two groups of schwannomas.

RESULTS

Twelve facial and 128 vestibular schwannomas met inclusion criteria. In only one case was a facial schwannoma diagnosed preoperatively from imaging. No statistically significant difference was found in preoperative House-Brackmann scores, ENoG, cVEMP, caloric testing, ABRs, or acoustic reflexes. Pure tone average was worse in the vestibular schwannoma group (63 dB [95% CI: 58-68 dB] vs. 46 dB [95% CI: 34-58 dB], P = .01), and the difference was more apparent in the lower frequencies. Word recognition score was better in the facial schwannoma group (66% [95% CI: 45-86%] vs. 41% [95% CI: 34-47%], P = .02).

CONCLUSION

Specialized preoperative functional evaluation of the nerves of the internal auditory canal cannot reliably predict the presence of an intracranial facial schwannoma. Hearing is better in facial schwannomas, particularly in the lower frequencies. This should raise the index of suspicion for an intracranial facial schwannoma, especially in candidates for hearing preservation vestibular schwannoma surgery.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:2098-2105, 2021.

Trends in the Management of Non-Vestibular Skull Base and Intracranial Schwannomas

The aim of this review is to analyze the latest trends in the management of non-vestibular skull base and intracranial schwannomas in order to optimize tumor control and quality of life. Non-vestibular cranial nerve schwannomas are rare lesions, representing 5–10% of cranial nerve schwannomas. Management decisions should be individualized depending on tumor size, location and associated functional deficits. Generally, large sized schwannomas exerting significant mass effect with increased intracranial pressure are treated surgically. In some cases, even after optimal skull base resection, it is not possible to achieve a gross total resection because tumor location and extent and/or to reduce morbidity. Thus, subtotal resection followed by stereotactic radiosurgery or fractioned radiotherapy offers an alternative approach. In certain cases, stereotactic radiosurgery or radiotherapy alone achieves good tumor control rates and less morbidity to gross total resection. Finally, given the slow growth rate of most of these tumors, observation with periodic radiographic follow-up approach is also a reasonable alternative for small tumors with few, if any, symptoms.

Recent advancements in understanding the role of epigenetics in the auditory system

Sensorineural deafness in mammals is most commonly caused by damage to inner ear sensory epithelia, or hair cells, and can be attributed to genetic and environmental causes. After undergoing trauma, many non-mammalian organisms, including reptiles, birds, and zebrafish, are capable of regenerating damaged hair cells. Mammals, however, are not capable of regenerating damaged inner ear sensory epithelia, so that hair cell damage is permanent and can lead to hearing loss. The field of epigenetics, which is the study of various phenotypic changes caused by modification of genetic expression rather than alteration of DNA sequence, has seen numerous developments in uncovering biological mechanisms of gene expression and creating various medical treatments. However, there is a lack of information on the precise contribution of epigenetic modifications in the auditory system, specifically regarding their correlation with development of inner ear (cochlea) and consequent hearing impairment. Current studies have suggested that epigenetic modifications influence differentiation, development, and protection of auditory hair cells in cochlea, and can lead to hair cell degeneration. The objective of this article is to review the existing literature and discuss the advancements made in understanding epigenetic modifications of inner ear sensory epithelial cells. The analysis of the emerging epigenetic mechanisms related to inner ear sensory epithelial cells development, differentiation, protection, and regeneration will pave the way to develop novel therapeutic strategies for hearing loss.

Long-term results of Gamma Knife radiosurgery for facial nerve schwannomas

OBJECTIVE

Long-term outcomes of eleven cases of facial nerve schwannoma were evaluated and the related literature was reviewed to determine the efficacy of Gamma Knife radiosurgery for treating patients with facial nerve schwannoma.

METHODS

Eleven patients with facial nerve schwannoma (7 women and 4 men; mean age, 44.2 years; range, 19-73 years) underwent Gamma Knife radiosurgery. The most common symptoms were facial palsy (n = 10) and hearing loss (n = 7). Five patients presented with headache. Two patients had undergone prior resection. The patients' clinical and radiographic data were evaluated retrospectively.

RESULTS

For the 11 cases of facial nerve schwannoma, mean tumor volume was 3.1 cm³ (range, 0.4-7.4 cm³) and the mean marginal dose applied was 11.9 Gy (range, 11-13 Gy). The mean follow-up period was 84.3 months (range, 66-117 months). Tumor control was achieved in all patients. At the time of writing, four patients experienced tumor volume regression and the other seven were in stable condition. During follow-up, nine patients experienced no change in their facial function, two experienced deteriorated facial function, and none developed new facial palsy. Ten patients who had serviceable hearing prior to Gamma Knife radiosurgery retained their hearing.

CONCLUSIONS

Gamma Knife radiosurgery achieves excellent results with respect to tumor control for 7 years on average. In addition, Gamma Knife radiosurgery provides good results in facial nerve and hearing function at long term. Our series demonstrates that Gamma Knife radiosurgery is an effective and safe treatment for patients with either primary or residual facial nerve schwannoma.

Oculomotor Neurofibroma: A Different Histology Implying an Unsatisfying Clinical Outcome

BACKGROUND

Tumors arising from oculomotor nerve are rare, with few cases reported in the literature. Generally, whereas schwannomas are well encapsulated tumors, neurofibromas tend to invade the entire nerve fibers. These differences influence surgical resection and neurological clinical outcome, with neurofibroma often requiring the sacrifice of the nerve. Accordingly, an incorrect preoperative diagnosis can lead to incomplete patient counseling before surgery.

CASE DESCRIPTION

We report 2 cases: a patient with oculomotor schwannoma and a patient with oculomotor neurofibroma. After tumor resection, the patient with a diagnosis of schwannoma recovered with 3rd nerve palsy, while patient with the neurofibroma developed a complete oculomotor nerve deficit. For each patient, surgical strategy and neurological outcome are elucidated in relation with differences in preoperative magnetic resonance imaging and histology.

CONCLUSIONS

To the best of our knowledge, this is the first report of an oculomotor neurofibroma. When an oculomotor nerve tumor is suspected, a careful preoperative evaluation of magnetic resonance imaging guides in distinguishing the different histology, in selecting the treatment strategy, and in correctly informing the patient on expected postoperative neurologic outcome.

Facial paralysis: Clinical practice guideline of the Spanish Society of Otolaryngology

Bell's palsy is the most common diagnosis associated with facial nerve weakness or paralysis. However, not all patients with facial paresis/paralysis have Bell's palsy. Other common causes include treatment of vestibular schwannoma, head and neck tumours, iatrogenic injuries, Herpes zoster, or trauma. The approach to each of these conditions varies widely. The purpose of this guideline is to provide clinicians with guidance on the treatment and monitoring of patients with different causes of facial paralysis. We intend to draft a practical guideline, focusing on operationalised recommendations deemed to be useful in the daily management of patients. This guideline was promoted by the Spanish Society of Otolaryngology and developed by a group of physicians with an interest in facial nerve disorders, including at least one physician from each Autonomous Community. In a question and answer format, it includes 56 relevant topics related to the facial nerve.

Facial Nerve Schwannoma Complicated by Acute Hemorrhage After Treatment with Stereotactic Radiosurgery

BACKGROUND

Facial nerve schwannomas (FNSs) are rare benign tumors that arise from Schwann cells of the facial nerve. FNSs are similar to vestibular schwannomas in many aspects, yet their infiltrative nature into the facial nerve fascicles warrants a more conservative management approach. In the last decade, stereotactic radiosurgery (SRS) has shown promise in stabilizing or shrinking FNSs.

CASE DESCRIPTION

A 71-year-old woman presented with mild facial paresis. Tumor growth after a period of watchful waiting warranted treatment with SRS, which was complicated by an acute posterior fossa hemorrhage and brainstem compression, necessitating microsurgical hematoma evacuation, tumor resection, and facial nerve substitution.

CONCLUSIONS

SRS has led to better facial nerve function and outcomes and is currently considered a reasonable alternative to microsurgical resection in patients with FNSs. This is the first report to our knowledge of an acute, life-threatening hemorrhage after SRS in a patient with FNS.