Repeat stereotactic radiosurgery for progressive vestibular schwannomas after previous radiosurgery: a systematic review and meta-analysis

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

BACKGROUND

Management of neurofibromatosis type 2 (NF2)- associated vestibular schwannomas (VSs) is challenging due to their multiplicity, early onset, proximity to the brainstem, unpredictable growth, and aggressive behavior. The optimal therapeutic intervention remains controversial in the literature, and the advantages and disadvantages of each treatment option should be evaluated for each patient. Stereotactic radiosurgery (SRS) has exhibited favorable results in the management of NF2-associated VSs. This systematic review and meta-analysis aimed to assess the role of SRS in NF2-associated VSs.

METHODS

On August 22, 2024, four electronic databases, comprising PubMed, Embase, Scopus, and Web of Science, were comprehensively searched. Studies that assessed SRS's radiological and clinical outcomes in NF2-associated VSs were enrolled.

RESULTS

Nineteen studies were included with 960 individuals and 1310 NF2-associated VSs. The analysis showed a pooled local control (LC) rate of 83% (95%CI:74-90%). Older age (P = 0.001), prior resection (P = 0.003), and lower tumor volume (P = 0.019) were associated with higher LC rates. The results demonstrated a pooled serviceable hearing preservation (SHP) rate of 42% (95%CI:34-51%), trigeminal nerve worsening rate of 2% (95%CI:1-4%), and a facial nerve worsening rate of 5% (95%CI:2-9%). None of the patients experienced radionecrosis (RN) following SRS. Sensitivity analyses revealed a moderate to high robustness of the results. No publication bias was identified.

CONCLUSION

SRS is an effective therapeutic modality for managing VSs, especially small-to medium-sized lesions. We showed that SRS is associated with favorable LC and SHP rates and considerably low trigeminal or facial nerve worsening and RN rates.

Clinical Outcomes of Salvage Microsurgical Resection after Radiation Therapy for Sporadic Vestibular Schwannomas

Background  The purpose of this study was to evaluate clinical outcomes after salvage microsurgery for vestibular schwannoma (VS) treated initially with modern radiotherapy techniques as compared to those treated with primary microsurgical resection. Methods  Patients who underwent microsurgical resection of sporadic VS undergoing a translabyrinthine approach at a single academic skull base tertiary referral center were included. Baseline and postoperative dynamic gait index, functional gait assessment, House-Brackmann facial nerve grading, and completeness of resection were prospectively recorded. Results  Of the 265 patients reviewed, 21 (7.9%) patients underwent prior radiation. Median age of the cohort was 55 years (interquartile range: 51-63). The likelihood of achieving a gross total resection was significantly lower for radiated as compared to nonradiated patients (odds ratio: 0.18, 95% confidence interval: 0.05-0.53, p  = 0.004) when controlling for tumor size. Radiated patients had better postoperative facial nerve function on the first postoperative day, but this difference was not significant at long-term follow-up. Radiated patients had lower preoperative postural stability scores than nonradiated patients on FGA (26 vs. 23, p  = 0.035). Postoperatively, radiated patients had comparable outcomes compared to nonradiated patients when controlling for age and tumor size. Conclusion  Compared to patients with VS treated with surgery alone, previously radiated patients are less likely to achieve gross total resection in the salvage setting. Radiated patients scored better on facial nerve outcomes compared to nonradiated patients in the initial postoperative period but demonstrated similar long-term outcomes.

Dynamics of tumor evolution after Gamma Knife radiosurgery for sporadic vestibular schwannoma: Defining volumetric patterns characterizing individual trajectory

BACKGROUND

The definition of tumor control and treatment failure after Gamma Knife radiosurgery (GKRS) for vestibular schwannoma (VS) is still debated. The lack of knowledge on the dynamics of tumor evolution can lead to misinterpretation and subsequent inappropriate second treatment. The aim of this study was to evaluate the post-GKRS dynamics of the evolution of tumor volume and characterize volumetric patterns.

METHODS

We included patients with sporadic VS treated by GKRS with an MRI follow-up of a minimum of 3 years. A clustering was performed in 2 steps: Definition of the patterns of evolution based on a subset of patients with the most comprehensive follow-up, and then the assignment of the remaining patients on a best-fit basis. The minimum length of follow-up was assessed by measuring the consistency of the clusters over time (adjusted rand index and normalized mutual information). An analysis of the discriminant variables was finally performed.

RESULTS

A total of 1607 patients were included (median follow-up: 67 months). Five patterns were defined with 1 pattern gathering almost all cases of treatment failure. The clustering at 5 years afforded the highest consistency with long-term follow-up. Discriminant variables for clusters were as follows: sex, initial symptoms, delay of diagnosis, Koos grading, fundus invasion, and number of isocenters.

CONCLUSIONS

The definition of these robust distinct patterns is likely to help the physicians tremendously to distinguish tumor control from potential failure. We advocate for no retreatment decision before 5 years post-GKRS. Further investigations are required to decide if the dynamics of evolution can be predicted at GKRS on an individual basis.

Stereotactic Radiosurgery for Vestibular Schwannoma - A Case-Based Practice Guide From the Radiosurgery Society

PURPOSE

Vestibular schwannomas (VS) are the most common benign intracranial nerve sheath tumors. Surgery and radiation therapy - particularly stereotactic radiosurgery (SRS) - are the primary treatment options. SRS is the dominant treatment for small- and medium-sized VS and selected larger tumors due to its excellent local control rates and favorable safety profile compared with surgery. However, careful treatment planning is essential, taking into account patient preferences, tumor location and size, symptoms, and anticipated treatment-related toxicity.

METHODS AND MATERIALS

Four clinical VS scenarios have been selected to illustrate the use of SRS, including a unilateral small intracanalicular VS, a large VS with cystic components, reirradiation with SRS after local tumor recurrence, and bilateral VS in the setting of neurofibromatosis type 2-related schwannomatosis.

RESULTS

SRS is an effective and safe treatment modality for the majority of VS cases, requiring careful treatment planning and a thorough understanding of potential limitations and challenges.

CONCLUSIONS

This case-based practice guide aims to provide a concise overview of the treatment of VS with SRS. We present and discuss 4 different clinical scenarios of VS to highlight the pitfalls and best practice recommendations.

Repeat stereotactic radiosurgery in vestibular schwannoma patients: A systematic review and meta-analysis

BACKGROUND

Regarding the newly diagnosed vestibular schwannomas (VSs), active surveillance, microsurgical resection (MS), and stereotactic radiosurgery (SRS) are the leading treatment options. Although SRS is an effective intervention with a low incidence of complications, failure may occur occasionally. Several options, including repeat SRS, are considered salvage treatment after failure of the SRS. In this systematic review and meta-analysis study, we aimed to evaluate the efficacy and outcomes of repeat stereotactic radiosurgery (SRS) in progressive VS following the failure of the initial SRS.

METHOD

The electronic databases of PubMed/Medline, Scopus, Embase, and Web of Science (WOS) were searched from inception to August 23rd, 2024. Studies that evaluated the role of repeat SRS in the setting of VS were included. The risk of bias was assessed using the Risk of Bias in Non-Randomized Studies of Interventions tool. The R program performed the meta-analyses, sensitivity analysis, publication bias, and meta-regression.

RESULTS

A total of 11 studies encompassing 260 VS patients with repeat SRS were included in our study. The median time interval between initial and repeat SRSs ranged from tumor volume ranged from 43 to 62 months. Our analysis revealed a pooled tumor control of 91 % (95 % CI: 86 %-94 %). Regarding the radiological response, the pooled regression rate was 59 % (95 % CI: 52 %- 65 %), while the pooled progression rate was 9 % (95 % CI: 6 %- 14 %). Regarding the clinical outcomes, the pooled serviceable hearing preservation (SHP) rate was 36 % (95 % CI: 22 %-53 %), while worsened fifth cranial nerve (CN) and seventh CN rates were 12 % (95 % CI: 7 %- 19 %) and 8 % (95 % CI: 5 %- 12 %), respectively. In addition, the pooled adverse radiation effect (ARE) rate was 6 % (95 % CI: 3 %- 11 %).

CONCLUSION

Our results suggest that the repeat SRS following the failure of the initial SRS in VS is associated with favorable outcomes, including tumor control, SHP, and CN worsening concurrent with low ARE rates.

Repeat stereotactic radiosurgery for progressive vestibular schwannomas after primary gamma knife radiosurgery

PURPOSE

Limited data provides guidance on the management of vestibular schwannomas (VSs) that have progressed despite primary Gamma Knife radiosurgery (GKRS). The present article reports our long-term experience after repeat GKRS for VS with sustained progression after solely primary GKRS management.

METHODS

A retrospective review of 1997 patients managed between 1987 and 2023 was conducted. Eighteen patients had sustained tumor progression after primary GKRS and underwent repeat GKRS. The median repeat GKRS margin dose was 11 Gy (IQR: 11-12), the median tumor volume was 2.0 cc (IQR: 1.3-6.3), and the median cochlear dose in patients with preserved hearing was 3.9 Gy (IQR: 3-4.1). The median time between initial and repeat GKRS was 65 months (IQR: 38-118).

RESULTS

The median follow-up was 70 months (IQR: 23-101). After repeat GKRS, two patients had further tumor progression at 4 and 21 months and required partial resection of their tumors. The 10-year actuarial tumor control rate after repeat GKRS was 88%. Facial nerve function was preserved in 13 patients who had House-Brackmann grade 1 or 2 function at the time of repeat GKRS. Two patients with serviceable hearing preservation (Gardner-Robertson grade 1 or 2) at repeat GKRS retained that function afterwards. In patients with tinnitus, vestibular dysfunction, and trigeminal neuropathy, symptoms remained stable or improved for 16/16 patients, 12/15 patients, and 10/12 patients, respectively. One patient developed facial twitching in the absence of tumor growth 21 months after repeat GKRS.

CONCLUSIONS

Repeat GKRS effectively controlled tumor growth and preserved cranial nerve outcomes in most patients whose VS had sustained progression after initial primary radiosurgery.

Repeat Radiosurgery for Sporadic Vestibular Schwannoma After Primary Radiosurgical Failure: An International Multi-institutional Investigation

OBJECTIVE

To describe outcomes of patients with sporadic vestibular schwannoma (VS) who underwent repeat stereotactic radiosurgery (SRS) after primary SRS failure.

STUDY DESIGN

Multi-institutional historical cohort study.

SETTING

Five tertiary care referral centers.

PATIENTS

Adults ≥18 years old with sporadic VS.

INTERVENTION

Primary and repeat treatment with SRS.

MAIN OUTCOME MEASURE

Microsurgery-free survival after repeat SRS.

RESULTS

Across institutions, 32 patients underwent repeat SRS after primary SRS. Most patients (74%) had tumors with cerebellopontine angle extension at primary SRS (median size, 13.5 mm [interquartile range, 7.5-18.8] mm). After primary SRS, patients underwent repeat SRS at a median of 4.8 years (interquartile range, 3.2-5.7 yr). For treatment modality, 30 (94%) patients received gamma knife for primary treatment and 31 (97%) patients received gamma knife as their repeat treatment. Median tumor volume increased from 0.970 cm3 at primary SRS to 2.200 cm3 at repeat SRS. Facial nerve function worsened in two patients after primary SRS and in two patients after repeat SRS. There were no instances of intracranial complications after repeat SRS. Microsurgery-free survival rates (95% confidence interval; number still at risk) at 1, 3, and 5 years after repeat SRS were 97% (90-100%, 24), 84% (71-100%, 13), and 68% (48-96%, 6), respectively. There was one occurrence of malignancy diagnosed after repeat radiosurgery.

CONCLUSION

Overall, repeat SRS for sporadic VS has comparable risk profile, but lower rates of tumor control, compared with primary SRS.

Adaptive treatment strategy for a vestibular schwannoma in a patient with vascular Eagle syndrome: illustrative case

BACKGROUND

Eagle syndrome, an uncommon condition, causes symptoms due to neural and/or vascular compression from an elongated styloid process or calcified stylohyoid ligament and can also complicate other planned surgical procedures.

OBSERVATIONS

A 42-year-old female with loss of balance, dizziness, and ataxic gait underwent cranial magnetic resonance imaging (MRI), revealing a right-sided Koos grade IV vestibular schwannoma. Initially, a retrosigmoid craniotomy for tumor resection was planned. However, preoperative MRI and computed tomography (CT) showed a dilated right-sided mastoid emissary vein, tortuous scalp and paraspinal veins, and bilateral elongated styloid processes. CT angiography and digital subtraction angiography indicated Eagle syndrome-related compression of both internal jugular veins and concurrent occlusion of the left internal jugular vein at the jugular foramen. Consequently, given the risk of damaging venous structures, Gamma Knife radiosurgery was chosen over resection.

LESSONS

This case highlights the importance of adapting treatment plans based on patient-specific anatomical and pathological factors. In situations in which traditional surgery poses risks to sensitive structures such as the venous system, alternative approaches like radiosurgery offer safer yet effective options. Comprehensive risk-benefit evaluations are crucial for such decisions.

Stereotactic radiosurgery for the treatment of hypoglossal schwannoma: a multi-institutional retrospective study

BACKGROUND

Surgical removal has been performed as the first line treatment for symptomatic or enlarging hypoglossal schwannomas (HS). Stereotactic radiosurgery (SRS) offers a minimally invasive approach that may afford long-term tumor control for patients with HS particularly those who refuse or are unfit for surgery. This study evaluates outcomes after SRS performed for both newly diagnosed and residual tumors after incomplete resection.

METHODS

This retrospective, multi-institutional study involved patients treated with adjuvant or primary SRS for HS. The study end-points included local tumor response, clinical outcomes, and procedure-related complications. All the patients had Gamma Knife SRS.

RESULTS

The cohort included 12 patients (five females), median age at SRS 49.5 years (range, 37-76)]. The median tumor target volume was 5.9 cm³ (range, 0.7-27.23). At median imaging follow-up of 37 months (range, 6-153), tumor control was achieved in 11 patients. Tumor enlargement that was managed with surgical resection was noted at the 6-month follow-up in one patient. At median clinical follow-up of 30.5 months (range, 6-157), stability, or improvement of all pre-SRS signs and symptoms was noted in nine patients. Two patients experienced worsening of at least one pre-existing symptoms or sign. New-onset trapezius weakness was noted in one patient and tongue atrophy in two patients.

CONCLUSION

Single-fraction SRS appears to be a safe and effective upfront and adjuvant treatment option for HS. SRS may be recommended as an alternative to surgery for patients presenting with HS or as an adjuvant treatment following subtotal resection and at HS recurrence.

Stereotactic radiosurgery for hypoglossal schwannoma

Hypoglossal schwannomas (HS) are extremely rare neoplasms. Surgical resection has historically been the treatment of choice but carries a significant risk of postoperative neurological deficits and mortality. Stereotactic radiosurgery (SRS) is a minimally invasive approach that may afford long-term tumour growth. However, literature to determine the safety and effectiveness of SRS in the treatment of HS is scarce. We report on a patient who presented with progressive headache and dysphagia as well as tongue deviation to the left, due to a space-occupying lesion, consistent on brain MRI with a left HS. Primary SRS using a prescription dose of 12 Gy in a single fraction was used to treat the tumour without complications. By last follow-up, the tumour regressed, and the patient's symptoms improved. Our case shows that radiosurgery can be safe and effective for the management of HS.