Does NF2 status impact the results of combined surgery and adjunctive Gamma Knife surgery for large vestibular schwannomas?

Large vestibular schwannoma treated using a cranial nerve sparing approach with planned subtotal microsurgical resection and stereotactic radiosurgery: meta-analysis and International Stereotactic Radiosurgery Society (ISRS) practice guidelines

INTRODUCTION

Stereotactic radiosurgery (SRS) has become a standard of care for small- to medium- size vestibular schwannomas (VS), while the majority of patients with large VS still require microsurgical resection due to potential consequences of long tract and cranial nerve compression, intracranial hypertension or hydrocephalus.

METHODS

We performed a systematic review and meta-analysis of the literature specific to planned subtotal resection for large VSs followed by SRS to the residual tumor to inform clinical practice guideline development. The Medline and Embase databases were used to apply the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) approach to search for manuscripts reporting outcomes for large VSs treated with this paradigm, with a search end date of June 1st 2023. Crude outcomes were pooled using weighted random effects.

RESULTS

12 series met inclusion criteria reporting on treatment outcomes for 677 patients. Overall tumor control was 89.9% (86.9-92.9%, p < 0.001), with tumor stability observed in 43.9% (19.9-68%, p < 0.001) and tumor reduction in 39.9% (57-74.2%, p = 0.02) post-SRS. Facial nerve functional preservation immediately after microsurgery was 88.0% (82.7-93.3%, p < 0.001), improving to 94.4% (91.4-97.4%, p < 0.001) at last follow-up. Cochlear functional preservation immediately after microsurgery was 58.8% (33.2-84.4%, p < 0.001), decreasing to 57.4% (33-81.8%, p < 0.001) at last follow-up.

CONCLUSIONS

A cranial nerve sparing approach with planned subtotal microsurgical resection and SRS to the residual tumor achieves high rates of tumor control with highly satisfactory outcome of facial and cochlear functional preservation. Clinical practice consensus recommendations on behalf of the International Stereotactic Radiosurgery Society (ISRS) are also presented.

Stereotactic radiosurgery for vestibular schwannomas in neurofibromatosis type 2 patients: a systematic review and meta-analysis

INTRODUCTION

Neurofibromatosis type 2 (NF2) is characterized by often bilateral vestibular schwannomas (VS) that result in progressive hearing loss and compression of nearby brainstem structures causing cranial nerve palsies. Treatment of these tumors remains challenging, as both surgical removal and expectant management can result in symptom progression. Stereotactic radiosurgery (SRS) has been investigated for the management of NF2-associated VS; however, the role, promises, and pitfalls of this treatment modality remain unclear.

METHODS

Ovid MEDLINE, EMBASE, Web of Science, and Cochrane Reviews were searched for studies assessing SRS outcome in NF2-associated VS only. Primary endpoints included tumor control, serviceable hearing, presence of tinnitus, and cranial nerve V and VII symptoms.

RESULTS

A total of 16 studies (589 patients harboring 750 tumors) were analyzed. Clinical tumor control was achieved in 88% of cases (95% CI 80-95%); salvage surgery was needed in 8% (95% CI 4-13%) of cases. Treatment resulted in a worsening of pre-treatment serviceable hearing (OR = 0.26, p < 0.01), increased facial nerve (OR = 1.62, p < 0.01) and trigeminal nerve (OR = 1.42, p = 0.07) impairment. The incidence of vestibular symptoms and hydrocephalus were not consistently reported and thus could not be assessed.

CONCLUSIONS

The treatment of NF2-associated VS continues to pose a challenge, as current SRS regimens result in impaired hearing and worse cranial nerve comorbidities, despite achieving high tumor control. It remains unclear if these findings have to be regarded as treatment complications or, rather, continued disease progression.

Treatment Analysis and Overall Survival Outcomes of Patients With Bilateral Vestibular Schwannoma

OBJECTIVES

To investigate the clinical presentation, treatment breakdown, and overall survival (OS) outcomes of patients with neurofibromatosis type 2 (NF2)-associated bilateral vestibular schwannoma (NVS).

METHODS

The 2004 to 2016 National Cancer Database was queried for patients with a diagnosis of VS. The "Laterality" code was used to stratify patients into sporadic unilateral vestibular schwannoma (UVS) and NVS.

RESULTS

Of the 33,839 patients with VS, 155 (0.46%) were coded for NVS with an average age and tumor size of 37.4 ± 20.5 years and 23.5 ± 18.2 mm. Patients underwent observation (45.3%), surgery (29.3%), and radiotherapy (20.0%), and had a 5.8% 5-year mortality rate. Compared with UVS, NVS was negatively associated with receiving surgery (40.2% versus 29.3%, p = 0.02) while watchful observation was more prevalent (30.1% versus 45.3%, p = 0.001). In NVS, undergoing surgery was associated with larger tumor size (34.5 ± 21.2 versus 17.8 ± 13.3 mm, p = 0.001) and shorter diagnosis-to-treatment time (49.1 ± 60.6 versus 87.0 ± 78.5 d, p = 0.02), radiotherapy was associated with older age (44.4 ± 18.9 versus 35.2 ± 20.6 yr, p = 0.02) and longer diagnosis-to-treatment time (85.9 ± 77.9 versus 53.9 ± 65.5 d, p = 0.04), and observation was associated with smaller tumor size (17.8 ± 15.9 versus 28.0 ± 19.2 mm, p = 0.01). Kaplan-Meier log-rank analysis demonstrated similar 10-year OS between NVS and UVS patients (p = 0.58) without factoring the earlier age of presentation. Furthermore, there were no temporal changes in presentation/management of NVS, and OS was not dependent on the received treatment (p = 0.30).

CONCLUSIONS

With younger age, larger tumors, and more conservative management, NVS's OS was not treatment-dependent and was similar to sporadic UVS, though the latter should not be interpreted as similar life expectancies due to the much earlier presentation.

Facial Nerve Outcomes After Vestibular Schwannoma Microsurgical Resection in Neurofibromatosis Type 2

OBJECTIVE

The aim of this study is to investigate facial nerve outcomes after microsurgical resection in neurofibromatosis type 2 (NF2) compared to sporadic tumors.

STUDY DESIGN

Single institutional retrospective chart review.

SETTING

Tertiary referral center.

METHODS

All adult patients with NF2 vestibular schwannoma (VS) or sporadic VS who underwent microsurgical resection from 2008 to 2019 with preoperative magnetic resonance imaging (MRI) and 1 year of postsurgical follow-up were included. The primary outcome measure was postoperative House-Brackmann (HB) facial nerve score measured at first postoperative visit and after at least 10 months.

RESULTS

In total, 161 sporadic VSs and 14 NF2 VSs met inclusion criteria. Both median tumor diameter (NF2, 33.5 mm vs sporadic, 24 mm, P = .0011) and median tumor volume (NF2, 12.4 cm³ vs sporadic, 2.9 cm³, P = .0005) were significantly greater in patients with NF2. The median follow-up was 24.9 months (range, 12-130.1). Median facial nerve function after 1 year for patients with NF2 was HB 3 (range, 1-6) compared to HB 1 (range, 1-6) for sporadic VS (P = .001). With multivariate logistic regression, NF2 tumors (odds ratio [OR] = 13.9, P = .001) and tumor volume ≥3 cm³ (OR = 3.6, P = .025) were significantly associated with HB ≥3 when controlling for age, sex, extent of tumor resection, translabyrinthine approach, and prior radiation.

CONCLUSION

Tumor volume >3 cm³ and NF2 tumors are associated with poorer facial nerve outcomes 1 year following microsurgical resection.

Current Management of Large Vestibular Schwannomas for NF2 Patients in a National Reference Center

OBJECTIVE

Recently, treatment decision making for large vestibular schwannomas (VS) in patients with neurofibromatosis type 2 (NF2) has become increasingly challenging due to the availability of multiple therapeutic options including surgery, bevacizumab (an anti-VEGF), radiosurgery, and observation; and it often remains an arbitrary decision based on local practices without firm recommendations. Our objective is to discuss the multimodal treatment options for Koos IV VS in a national reference center for NF2.

STUDY DESIGN

Single-institution retrospective cohort study.

METHODS

All NF2 patients with Koos IV VS who visited our center, the National Reference Center for NF2 Rare Disease in Pitié-Salpétrière Hospital of Paris, between January 2016 and December 2018 were included. Clinical charts, radiology, operative reports, and audiograms were reviewed.

RESULTS

Among 54 NF2 patients with Koos IV VS (mean maximum extrameatal diameter: 34 mm; range:17-62 mm), 27 were operated on for 28 VS; 21 were treated with bevacizumab; and six were observed. In the surgical group, VS resections were gross total, near-total, subtotal, or partial in 32%, 25%, 32%, and 11%, respectively; and a good (House-Brackmann grades I-II) facial nerve function was achieved in 81.5% at 1 year. Hearing was preserved in 14%, 78%, and 66% of the surgical (n = 7), bevacizumab (n = 9), and observation (n = 3) patients, respectively.

CONCLUSION

All therapeutic options, including surgery and/or bevacizumab and occasionally observation, should be proposed to NF2 patients with large VS in the setting of dedicated centers. A decision-making tree is proposed for Koos IV VS management based on tumor evolution, hearing and clinical status of the patient, and contralateral VS size.

LEVEL OF EVIDENCE

4, case series study, historically controlled study Laryngoscope, 131:E98-E107, 2021.