Long-term outcomes of facial nerve schwannomas with favorable facial nerve function: tumor growth rate is correlated with initial tumor size

A, Rao KVLN, Somanna S. Surgical Management of Large (≥3 cm) Trigeminal Schwannomas: Functional Outcomes and Approach Selection in Multicompartmental Schwannomas

Introduction  Trigeminal schwannoma surgery has shown a remarkable improvement in functional recovery and tumor resection. In the era of radiosurgery, these outcomes need to be characterized for tumors which are outside the realm of being treated with radiosurgery. We present a series of trigeminal schwannomas larger than 3 cm, surgical approaches used, and outcomes with an emphasis on functional recovery in a high-volume center with radiosurgery facilities. Method  All consecutive cases of trigeminal schwannoma from January 2012 to May 2021 which were more than 3 cm in size and underwent microsurgery were included in this series. The surgical approach, neurological outcomes, and extent of resection were defined objectively with pre/postoperative magnetic resonance imaging. Results  A total of 83 such cases (>3 cm) were found, with cranial nerve symptoms (5th most common) being the commonest. Twenty three percent cases had blindness due to secondary optic atrophy and eighteen percent had long tract motor symptoms signifying the tumor burden in our series. Radiological gross total excision was achieved in 75.9% cases. Conclusion  Large-volume schwannomas present with cranial nerve involvement and may need extensive skull base approaches. Functional outcomes need to be prioritized and can be achieved albeit with lesser gross resection rates. Hearing and facial preservation in addition to relief of trigeminal symptoms should be the goal of resection with minimal additional morbidity.

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.

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.

Management of facial nerve schwannoma: when is the timing for surgery

PURPOSE

Although the estimated prevalence is extremely low, facial nerve schwannoma (FNS) is the most common primary tumor of the facial nerve (FN). In the present study, the outcome of surgical management in 18 patients with FNS was analyzed and an appropriate time for surgery was proposed.

MATERIALS AND METHODS

A total of 18 patients with FNS who underwent surgical management by a single surgeon from 1999 to 2018 were retrospectively analyzed.

RESULTS

Among the 18 patients, five had no facial paralysis before surgery. Near-total removal was performed in three cases, and two cases were managed with decompression. In 13 cases with various degree of preoperative facial palsy, nerve continuity was lost during surgery. FN was reconstructed using cable graft in ten cases, direct anastomosis in one case, and facial-hypoglossal nerve transfer in one case. Facial reanimation surgery without FN reconstruction was performed in one case due to a long-standing facial paralysis before surgery. Preoperative House-Brackmann (H-B) grade in all patients was significantly worse as tumor size increased. The correlation was not observed between the duration and severity of preoperative facial palsy. Analysis of 12 patients who underwent FN reconstruction revealed that all patients with good preoperative facial function (H-B grade II-III) recovered to H-B grade III after surgery (7/7, 100%). However, patients with poor preoperative facial function (H-B grade IV or worse) had only a 40% (2/5) chance of improving to grade III after surgery. Preoperative tumor size and duration of facial palsy did not affect postoperative final facial function.

CONCLUSION

We suggest that H-B grade III facial palsy is the best time for surgical intervention, regardless of the tumor size or duration of facial palsy.

Intratemporal facial nerve schwannomas: multicenter experience of 80 cases

PURPOSE

To provide more data on the clinical presentation and natural evolution of facial nerve schwannomas and to provide guidance for therapeutic decision making.

METHODS

A retrospective case review of eighty patients diagnosed with a facial nerve schwannoma between 1990 and 2018 in ten tertiary referral centers in Europe was performed. Patients' demographics, symptomatology, audiometry, anatomical site (segments involved), size and whenever possible volume measurement were registered.

RESULTS

At presentation, transient or persistent facial palsy was the most common symptom, followed by hearing loss. The schwannoma involved more than one segment in the majority of the patients with the geniculate ganglion being most commonly involved. Initial treatment consisted of a wait and scan approach in 67.5%, surgery in 30% and radiation therapy in 2.5% of the patients. Tympanic segment schwannomas caused mainly conductive hearing loss and were more prone to develop facial palsy at follow-up. Internal auditory canal or cerebellopontine angle schwannomas presented with significantly more sensorineural hearing loss.

CONCLUSIONS

Although modern imaging has improved diagnosis of this tumor, choosing the best treatment modality remains a real challenge. Based on the literature review and current findings, more insights into the clinical course and the management of facial nerve schwannomas are provided.

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.

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.

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.

Management of Facial Nerve Schwannoma: A Multicenter Study of 50 Cases

Objective  In the management of facial nerve schwannoma (FNS), surgical tumor resection is now often being replaced with more conservative approaches, such as observation with serial imaging or stereotactic radiosurgery (SRS). Given the scarcity of these lesions, determining the optimal management of FNS remains challenging and subject of debate with multiple treatment approaches supported in the literature. Methods  A retrospective chart review was performed in two academic centers for patients diagnosed with FNS between 1996 and 2017. The clinical presentation, treatment modalities employed, tumor control rates, and facial nerve function (FNF) outcomes (House-Brackmann system) were assessed and analyzed. Results  The study comprised 50 adult patients. Initial treatment modalities included observation with serial clinicoradiologic review in 27 patients (54%), surgery in 17 patients (34%), and SRS in 6 patients (12%). The FNF were decreased in more than half of the patients who had surgery. Nonetheless, more than 80% of the patients who were initially managed with observation or SRS had stable or improved FNF. Conclusion  A prevailing trend toward more conservative treatment modalities for FNS has evolved over time, providing relatively long-term preservation of FNF. As there are multiple management options available, it is of paramount importance that the treating physician be familiar with all treatment modalities and outcomes and counsel patients appropriately. The surgery should be reserved for large tumors and poor FNF at initial presentation or follow-up while watchful observation with imaging is the treatment of choice for rest of the patients.

Evaluation and Management of Facial Nerve Schwannoma

Facial nerve schwannomas are benign peripheral nerve sheath tumors that arise from Schwann cells, and most commonly present with facial paresis and/or hearing loss. Computed tomography and MRI are critical to diagnosis. Management decisions are based on tumor size, facial function, and hearing status. Observation is usually the best option in patients with good facial function. For patients with poor facial function, the authors favor surgical resection with facial reanimation. There is growing evidence to support radiation treatment in patients with progressively worsening moderate facial paresis and growing tumors.

Facial Nerve Schwannomas: Review of 80 Cases Over 25 Years at Mayo Clinic

OBJECTIVE

To elucidate the long-term clinical behavior, treatment, and outcomes of sporadic facial nerve schwannoma (FNS) in a large cohort of patients managed in the post-magnetic resonance imaging era.

PATIENTS AND METHODS

Retrospective review at a single tertiary health care system (January 1, 1990, through December 31, 2015), evaluating 80 consecutive patients with sporadic FNS.

RESULTS

Ninety-eight patients with FNS were identified; 10 with incomplete data and 8 with neurofibromatosis type 2 were excluded. The remaining 80 patients (median age, 47 years; 58% women) were analyzed. Forty-three (54%) patients presented with asymmetrical hearing loss, 33 (41%) reported facial paresis, and 21 (26%) reported facial spasm. Seventeen (21%) exhibited radiologic features mimicking vestibular schwannoma, 14 (18%) presented as a parotid mass, and 5 (6%) were discovered incidentally. Factors predictive of facial nerve paresis or spasm before treatment were female sex and tumor involvement of the labyrinthine/geniculate and tympanic facial nerve segments. The median growth rate among growing FNS was 2.0 mm/y. Details regarding clinical outcome according to treatment modality are described.

CONCLUSION

In patients with FNS, female sex and involvement of the labyrinthine/geniculate and tympanic segments of the facial nerve predict a higher probability of facial paresis or spasm. When isolated to the posterior fossa or parotid gland, establishing a preoperative diagnosis of FNS is challenging. Treatment should be tailored according to tumor location and size, existing facial nerve function, patient priorities, and age. A management algorithm is presented, prioritizing long-term facial nerve function.

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.