Gamma Knife Stereotactic Radiosurgery for Nonvestibular Cranial Nerve Schwannomas

Economic evaluation of stereotactic radiotherapy and stereotactic radiosurgery technologies in the treatment of cancers: a systematic review

INTRODUCTION

This systematic review study investigated the cost-effectiveness of stereotactic radiotherapy (SRT) and stereotactic radiosurgery (SRS) for treatment of various types of cancers.

METHODS

PubMed, Scopus, and Web of Science were searched from 30/12/1990 to 1/1/2023. The entered studies were screened in accordance with the inclusion criteria. The inclusion criteria encompassed all types of economic evaluation studies that investigated SRT/SRS technologies in the treatment of various cancers.

RESULTS

A total of 47 articles were included in the review. The findings suggest that the use of Linear accelerator technology for the treatment of lung cancer (8 out of 12 studies) and prostate cancer (4 out of 5 studies) was a cost-effective strategy. Linear accelerator was found to be cost-effective in the treatment of liver metastases and liver cancer (2 out of 5 studies). All of the included studies that used Gamma Knife technology in brain metastases reported Gamma-Knife was a cost-effective treatment. Furthermore, in the treatment of prostate and liver cancer, proton therapy was identified as a cost-effective option than other treatments.

CONCLUSIONS

This study confirms that SRT/SRS is a cost-effective procedure for the treatment of various types of cancers. Therefore, it is recommended to use SRT/SRS technology for optimal use of resources.

Lower Cranial Nerve Schwannomas: Cohort Study and Systematic Review

BACKGROUND AND OBJECTIVES

Schwannomas originating from the lower cranial nerves (LCNS) are rare and pose a significant surgical challenge. Resection is the mainstay treatment; however, risk of treatment morbidity is considerable, and the available literature regarding differential treatment outcomes in this vulnerable population is sparse.

METHODS

A single-institution cohort study and systematic literature review of LCNS were performed.

RESULTS

Fifty-eight patients were included: 34 underwent surgical resection and 24 underwent stereotactic radiosurgery (SRS). The median age at diagnosis was 48 years (range 17-74). Presenting symptoms were dysphagia (63%), dysarthria/hypophonia (47%), imbalance (33%), and hearing loss/tinnitus (30%). Tumor size was associated with surgical resection, as compared with initial SRS (4.1 cm vs 1.5 cm, P = .0001). Gross total resection was obtained in 52%, with tumor remnants predominantly localized to the jugular foramen (62%). Post-treatment worsening of symptoms occurred in 68% of surgical and 29% of SRS patients ( P = .003). Postoperative symptoms were mostly commonly hypophonia/hoarseness (63%) and dysphagia (59%). Seven patients (29%) had new neurological issues after SRS treatment, but symptoms were overall milder. The median follow-up was 60 months (range 12-252); 98% demonstrated meaningful clinical improvement. Eighteen surgical patients (53%) underwent adjuvant radiation at a median of 5 months after resection (range 2-32). At follow-up, tumor control was 97% in the surgical cohort and 96% among SRS patients.

CONCLUSION

Although LCNS resection is potentially morbid, most postoperative deficits are transient, and patients achieve excellent tumor control-particularly when paired with adjuvant SRS. For minimally symptomatic patients undergoing surgical intervention, we advise maximally safe resection with intracapsular dissection to preserve nerve integrity where possible. For residual or as a primary treatment modality, SRS is associated with low morbidity and high rates of long-term tumor control.

Long-term outcomes of stereotactic radiosurgery for intracranial schwannoma in neurofibromatosis type 2: a genetic analysis perspective

PURPOSE

Neurofibromatosis type 2 (NF2) is intractable because of multiple tumors involving the nervous system and is clinically diverse and genotype-dependent. Stereotactic radiosurgery (SRS) for NF2-associated schwannomas remains controversial. We aimed to investigate the association between radiosurgical outcomes and mutation types in NF2-associated schwannomas.

METHODS

This single-institute retrospective study included consecutive NF2 patients with intracranial schwannomas treated with SRS. The patients' types of germline mutations ("Truncating," "Large deletion," "Splice site," "Missense," and "Mosaic") and Halliday's genetic severity scores were examined, and the associations with progression-free rate (PFR) and overall survival (OS) were analyzed.

RESULTS

The study enrolled 14 patients with NF2 with 22 associated intracranial schwannomas (median follow-up, 102 months).　The PFRs in the entire cohort were 95% at 5 years and 90% at 10-20 years. The PFRs tended to be worse in patients with truncating mutation exons 2-13 than in those with other mutation types (91% at 5 years and 82% at 10-20 years vs. 100% at 10-20 years, P = 0.140). The OSs were 89% for patients aged 40 years and 74% for those aged 60 years in the entire cohort and significantly lower in genetic severity group 3 than in the other groups (100% vs. 50% for those aged 35 years; P = 0.016).

CONCLUSION

SRS achieved excellent PFR for NF2-associated intracranial schwannomas in the mild (group 2A) and moderate (group 2B) groups. SRS necessitates careful consideration for the severe group (group 3), especially in cases with NF2 truncating mutation exons 2-13.

Imaging of trochlear nerve schwannomas: a case series and systematic review of the literature

Purpose Trochlear nerve schwannomas are rare tumors. So far, only 121 cases have been published. We present four new cases, discuss the imaging characteristics and summarize all previously published cases through a systematic review.Methods Four cases, all treated in AZ Sint-Jan Hospital Brugge-Oostende (Belgium), were collected, including their demographic, clinical and radiological data. All MR imaging was performed with the three-dimensional fluid-attenuated inversion recovery (3D-FLAIR), turbo spin echo T1 high-resolution (TSE T1 HR), three-dimensional balanced fast-field echo (3D b-FFE) and three-dimensional T1 black blood (3D T1 black blood) sequence. We compared our findings with the present literature through a systematic literature review in accordance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines.Results Screening with routine unenhanced 3D-FLAIR imaging could identify all schwannomas as hyperintense lesions on the course of the trochlear nerve. The use of 3D T1 black blood sequences was superior in depicting the lesions, while high-resolution 3D b-FFE images enabled us to visualize the anatomic boundaries of the lesions in detail. Most trochlear schwannomas are located in the ambient cistern, at or just below the free edge of the tentorium.Conclusion The majority of trochlear nerve schwannomas are located cisternal and display variable enhancement on contrast administration. 3D-FLAIR imaging is superior in detecting these lesions. Comparison with data collected from previous cases demonstrates the importance of early diagnosis and treatment. Generally, patients with trochlear nerve schwannomas have a good prognosis.

Hemorrhagic schwannoma of the trochlear nerve: Case report and a review of the literature

Background

Schwannomas of the trochlear nerve with the absence of systemic neurofibromatosis are considerably uncommon, especially complicated by intra-tumoral hemorrhage. Due to the lack of typical clinical manifestations and imaging findings, a definite diagnosis of trochlear schwannomas before surgery is particularly difficult.

Case presentation

We report the case of a 64-year-old female patient who presented with a unilaterally intermittent headache of 2-month duration and without a remarkable neurological deficit at admission. Imaging studies revealed a well-demarcated cystic-solid lesion with mixed signals beside the brainstem and suprasellar cisterna. The patient underwent a surgical operation with total resection of the tumor by a subtemporal surgical approach. The tumor was intraoperatively found to originate from the trochlear nerve and was pathologically confirmed as a hemorrhagic schwannoma with cystic degeneration.

Conclusions

We describe this case in detail and conduct a concomitant survey of the literature, summarizing the clinical presentations, radiological features, surgical treatment, and the possible mechanisms of hemorrhage in relevance to trochlear nerve schwannoma.

The Treatment Outcome of CyberKnife-Based Stereotactic Radiotherapy for Intracranial and Extracranial Nonvestibular Schwannomas: A Single-Center Experience

BACKGROUND

Data on the outcomes of CyberKnife-based hypofractionated stereotactic radiosurgery (hSRS) for intracranial and extracranial nonvestibular schwannomas (nVSs) are not sufficient.

METHODS

Patients who underwent hSRS for nVSs between 2010 and 2019 were retrospectively reviewed.

RESULTS

A total of 39 patients with 39 nVSs were identified. The mean age was 53 (±18) years, and 20 patients (51%) were women. Twenty-five patients (64%) had previous surgeries. Seventeen patients (44%) had nVSs extending outside the cranium. The mean prescribed dose covering 95% of the planning target volume was 22 Gy (±3.7 Gy), the mean fractionation was 4 (±2), and the mean target volume was 13 cm³ (±16 cm³). The radiological tumor control rate was 100% during the mean follow-up period of 67 months (±37 months). Thirty-seven patients (95%) were clinically stable during the mean follow-up period of 72 months (±35 months). Nine patients (23%) suffered from transient adverse radiation effects (AREs), including transient tumor expansion, and 2 (5%) suffered from permanent AREs.

CONCLUSIONS

We summarized the treatment outcomes of hSRS for nVSs. Although all patients achieved radiological tumor control, the risk of either transient or permanent ARE was high. Therefore, it is necessary to monitor patients for clinical deterioration due to AREs.

Long-Term Outcomes of Stereotactic Radiosurgery for Trigeminal, Facial, and Jugular Foramen Schwannoma in Comparison with Vestibular Schwannoma

Simple Summary

Intracranial schwannomas are benign intracranial neoplasms. Vestibular schwannomas (VS) account for 90% of intracranial schwannomas; whereas the other cranial nerve schwannomas, such as trigeminal (TS), facial (FS), and jugular foramen schwannoma (JFS), account for 10% of all cases. Stereotactic radiosurgery (SRS) is a minimally invasive treatment for small to medium VS and known to provide excellent long-term tumor control; however, there remains a paucity of evidence regarding SRS for TS, FS, and JFS due to the rarity of these tumors. We investigated the radiosurgical outcomes of these non-vestibular schwannomas and compared them to those of VS through matched cohort analysis.

Abstract

Stereotactic radiosurgery (SRS) is known to provide excellent tumor control with functional preservation for vestibular schwannomas (VS), but its efficacy in the other major intracranial schwannomas including trigeminal (TS), facial (FS), and jugular foramen schwannomas (JFS) has not been established yet due to their rarity. We retrospectively analyzed data of 514 consecutive patients who had intracranial schwannomas (460 VS, 22 TS, 7 FS, and 25 JFS) and underwent SRS. The 5- and 10-year tumor control rates were 97% and 94% for VS, 100% and 100% for TS, 80% and 80% for FS, and 100% and 80% for JFS. Radiation-induced complications included one hydrocephalus for TS (4.5%), no cases for FS (0%), and one hydrocephalus and one lower palsy for JFS (8.0%). Through matched cohort analysis between patients with VS and each of the non-VS, we found no statistical difference in tumor control and radiation-induced adverse events. SRS seems to provide long-term tumor control with functional preservation for TS, FS and JFS and the efficacies are similar to VS.

Outcomes after stereotactic radiosurgery for schwannomas of the oculomotor, trochlear, and abducens nerves

OBJECTIVE

Cranial nerve (CN) schwannomas are intracranial tumors that are commonly managed by stereotactic radiosurgery (SRS). There is a large body of literature supporting the use of SRS for vestibular schwannomas. Schwannomas of the oculomotor nerves (CNs III, IV, and VI) are rare skull base tumors, occurring close to the brainstem and often involving the cavernous sinus. Resection can cause significant morbidity, including loss of nerve function. As for other schwannomas, SRS can be used to manage these tumors, but only a handful of cases have been published so far, often among reports of other uncommon schwannoma locations.

METHODS

The goal of this study was to collect retrospective multicenter data on tumor control, clinical evolution, and morbidity after SRS. This study was performed through the International Radiosurgery Research Foundation. Patients managed with single-session SRS for an oculomotor cranial nerve schwannoma (CN III, IV, or VI) were included. The diagnosis was based on diplopia or ptosis as the main presenting symptom and anatomical location on the trajectory of the presumed cranial nerve of origin, or prior resection confirming diagnosis. Demographic, SRS dose planning, clinical, and imaging data were collected from chart review of the treated patients. Chi-square and Kaplan-Meier analyses were performed.

RESULTS

Seven institutions submitted data for a total of 25 patients. The median follow-up time was 41 months. The median age at the time of treatment was 52 years. There were 11 CN III schwannomas, 11 CN IV schwannomas, and 3 CN VI schwannomas. The median target volume was 0.74 cm3, and the median marginal dose delivered was 12.5 Gy. After SRS, only 2 patients (including the only patient with neurofibromatosis type 2) had continued tumor growth. Crude local control was 92% (23/25), and the 10-year actuarial control was 86%. Diplopia improved in the majority of patients (11/21), and only 3 had worsening following SRS, 2 of whom also had worsened ptosis, both in the context of tumor progression.

CONCLUSIONS

SRS for schwannomas of the oculomotor, trochlear, and abducens nerves is effective and provides tumor control rates similar to those for other cranial nerve schwannomas. SRS allows improvement of diplopia in the majority of patients. SRS should therefore be considered as a first-line treatment option for oculomotor nerve schwannomas.

Oculomotor Schwannomas: A Systematic Review and Report of Two Pediatric Cases Treated with Fractionated Cyberknife Stereotactic Radiotherapy

OBJECTIVE

Pediatric oculomotor nerve schwannomas are rare and challenging lesions due to the high morbidity associated with surgical intervention and their proximity to critical structures limiting the opportunity for stereotactic radiosurgery. We aim to report and review the novel use of fractionated Cyberknife (Accuray, Inc., Sunnyvale, California, USA) stereotactic radiotherapy in pediatric patients with oculomotor schwannomas.

METHODS

A systematic review of PubMed, Embase, and Cochrane was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Two patients, ages 8 and 10 years, with tumor volumes of 0.1 cm³ and 0.2 cm³, respectively, were treated with fractionated Cyberknife radiotherapy at our institution. A total dose of 45-50 Gy was administered over 25 fractions (1.8-2.0 Gy per fraction) to the 82%-84% isodose line. Serial magnetic resonance imaging was obtained for long-term follow-up (56-58 months).

RESULTS

We found 14 articles published between 1982 and 2018 that reported a total of 18 pediatric patients with intracranial oculomotor schwannomas. No previously described cases of pediatric intracranial oculomotor schwannomas were treated with radiation therapy. In both of our patients, radiographic tumor control was achieved at a mean follow-up of 57 months, with 1 patient displaying a decrease in tumor volume. Neither patient exhibited any worsening of their presenting symptoms, nor did either patient develop any new neurocognitive deficits following treatment.

CONCLUSIONS

Fractionated Cyberknife radiotherapy is an effective and well-tolerated treatment option for intracranial oculomotor nerve schwannomas with excellent tumor control rates, similar to surgical and radiosurgical techniques, while sparing critical surrounding structures.

Rapidly Growing and Asymptomatic Skull Base Lesion

Trochlear schwannomas typically present with diplopia and are extremely rare benign intracranial neoplasms that require the combined expertise of neurotologists and neurosurgeons for surgical excision. A combined petrosal approach offers a surgical route for removal of growing and/or symptomatic tumors. A study of a trochlear nerve schwannoma that demonstrated rapid growth but was otherwise asymptomatic was presented in this study.