Results for local control and functional outcome after linac-based image-guided stereotactic radiosurgery in 190 patients with vestibular schwannoma

Tumor Control Following Stereotactic Radiosurgery in Patients with Vestibular Schwannomas - A Retrospective Cohort Study

BACKGROUND

To better counsel vestibular schwannoma patients, it is necessary to understand the tumor control rates of stereotactic radiosurgery (SRS).

OBJECTIVES

To determine tumor control rates, factors determining control and complication rates following SRS.

METHODS

Tertiary hospital retrospective cohort.

RESULTS

579 tumors (576 patients) were treated with SRS. 477 tumors (474 patients, 82%) had ≥1 year follow up and 60% (344) ≥3 years follow up. 88% of tumors had primary SRS and 6.7% salvage SRS. Median follow up time was 4.6 years. At 3 years, the tumor control rate of primary SRS was 89% (258 of 290) in sporadic tumors compared to 43% in Neurofibromatosis type II (3 of 17) (p < 0.01). Our bivariable survival data analysis showed that Neurofibromatosis type II, documented pre-SRS growth, tumor measured by maximum dimension, SRS given as nonprimary treatment increased hazard of failure to control. There was one case of malignancy and another of rapid change following intra-tumoral hemorrhage. For tumors undergoing surgical salvage (25 of 59), 56% had a total or near-total resection, 16% had postoperative CSF leak, with 12% new facial paralysis (House-Brackmann grade VI) and worsening of facial nerve outcomes (House-Brackmann grade worse in 59% at 12 mo).

CONCLUSIONS

Control of vestibular schwannoma after primary SRS occurs in the large majority. Salvage surgical treatment was notable for higher rates of postoperative complications compared to primary surgery reported in the literature.

Stereotactic Radiosurgery for Vestibular Schwannomas: Reducing Toxicity With 11 Gy as the Marginal Prescribed Dose

Background

Stereotactic radiosurgery (SRS) is a common treatment option for vestibular schwannomas. Historically, a dose de-escalation of the marginal prescribed dose from 16 Gy to 12–13 Gy has been done to limit toxicity without reducing local control (LC). We aimed to retrospectively report outcomes of Linac-based SRS for vestibular schwannomas treated with different doses.

Methods

Included in the study were 97 stage 1 (1%), 2 (56%), 3 (21.5%), and 4 (21.5%) vestibular schwannomas treated with Linac-based (Novalis^®) SRS from 1995 to 2019. No margin was added to the GTV to create the PTV. The median marginal prescribed dose was 14 Gy (range: 12–16 Gy) before 2006 and then 11 Gy for all patients (61 pts). Mean tumor volume was 1.96 cm³, i.e., about 1.6 cm in diameter. Mean follow-up was 8.2 years.

Results

Following SRS, LC at 3, 5, and 10 years was 100%, 98.4%, and 95.6%, respectively [100% for those with ≤ 13 Gy as the marginal prescribed dose (NS)]. Toxicity to the trigeminal nerve was reported in 7.2% of cases (3.3% and 0% for transient and permanent toxicity for 11 Gy). The marginal prescribed dose was the only significant predictive factor in univariate and multivariate analysis (HR = 1.77, 95% CI = 1.07–3.10, p = 0.028). Toxicity to the facial nerve was reported in 6.2% of cases. The marginal prescribed dose was again the only significant predictive factor in univariate and multivariate analysis (HR = 1.31, 95% CI = 0.77–2.23, p = 0.049).

Conclusion

Linac-based SRS for stages 1–3 vestibular schwannomas provides excellent outcomes: a 10-year LC rate of over 95%, with a permanent facial or trigeminal toxicity rate of under 5%. A marginal prescribed dose of 11 Gy seems to decrease nerve toxicity and facial toxicity in particular, without reducing LC. Prospective studies with longer follow-up are needed.

Long-term outcomes of patients with primary or residual vestibular schwannoma treated with LINAC-based stereotactic radiosurgery: a single-centre experience

Aim:

Vestibular schwannomas (VS) are benign slow-growing tumours treated either with microsurgery or stereotactic radiosurgery (SRS) or both. The aim of this study was to correlate the outcome factors—tumour control and adverse factors—facial nerve function and hearing loss with patient and treatment factors.

Materials and methods:

A retrospective review of the records of 98 patients with 99 VS treated from June 2007 to June 2014, all patients receiving Linear Accelerator (LINAC)-based SRS.

Results:

Median follow-up period was 5·6 years (range: 1–12 years). The response to treatment was stable disease in 37 (37·4%), regression in 46 (46·5%), asymptomatic minimal progression in 9 (9·1%) and symptomatic progression in 5 (5%) and unknown in 2 (2%) patients. There was no evidence of SRS induced tissue damage on magnetic resonance scans for any. Hearing preservation rate after SRS was 92%. The patients who developed worsening of facial function were predominantly in the cohort that had prior surgery.

Findings:

SRS is an effective modality to treat VS lesser than 3 cm in size. Tumour control rate was 95% with a median follow-up period of 5·6 years. The complication rates were 8% each for facial function worsening and worsening of hearing. Prior surgery was a statistically significant factor that affected facial nerve function deterioration.

Progressive Vestibular Schwannoma following Subtotal or Near-Total Resection: Dose-Escalated versus Standard-Dose Salvage Stereotactic Radiosurgery

Objective  Local failure of incompletely resected vestibular schwannoma (VS) following salvage stereotactic radiosurgery (SRS) using standard doses of 12 to 13 Gy is common. We hypothesized that dose-escalated SRS, corrected for biologically effective dose, would have superior local control of high-grade VS progressing after subtotal or near-total resection compared with standard-dose SRS. Design  Retrospective cohort study. Setting  Tertiary academic referral center. Participants  Adult patients treated with linear accelerator-based SRS for progressive VS following subtotal or near-total resection. Main Outcome Measures  Dose-escalated SRS was defined by a biologically effective dose exceeding a single-fraction 13-Gy regimen. Study outcomes were local control and neurologic sequelae of SRS. Binary logistic regression was used to evaluate predictors of study outcomes. Results  A total of 18 patients with progressive disease following subtotal (71%) and near-total (39%) resection of Koos grade IV disease (94%) were enrolled. Of the 18 patients, 7 were treated with dose-escalated SRS and 11 with standard-dose SRS. Over a median follow-up of 32 months after SRS, local control was 100% in the dose-escalated cohort and 91% in the standard-dose cohort ( p  = 0.95). Neurologic sequelae occurred in 28% of patients, including 60% of dose-escalated cohort and 40% of the standard-dose cohort ( p  = 0.12), although permanent neurologic sequelae were low at 6%. Conclusions  Dose-escalated SRS has similar local control of recurrent VS following progression after subtotal or near-total resection and does not appear to have higher neurologic sequalae. Larger studies are needed.

Preoperative Assessment of Cervical Vestibular Evoked Myogenic Potentials (cVEMPs) Help in Predicting Hearing Preservation After Removal of Vestibular Schwannomas Through a Middle Fossa Craniotomy

OBJECTIVE

To determine whether cervical vestibular evoked myogenic potentials (cVEMPs) are predictive of hearing preservation in patients undergoing vestibular schwannoma removal through middle fossa craniotomy approach.

STUDY DESIGN

Retrospective case study.

SETTING

Tertiary referral center.

PATIENTS

Eighteen patients who underwent a middle fossa craniotomy for vestibular schwannoma (stage I or II of Koos classification) with attempted hearing preservation from January 2008 to February 2016 were retrospectively reviewed.

INTERVENTION

Pre-surgical cVEMPs test, videonystagmography (caloric test), and magnetic resonance imaging (MRI) as well as a pre- and post-surgical audiometry test.

MAIN OUTCOME MEASURES

cVEMPs parameters including amplitude asymmetry ratio (AR), P13, and N23 latencies and peak-to-peak amplitude between P13 and N23 waves were calculated. Hearing data were classified according to the AAO-HNS hearing classes. The nerve of origin of the tumor was specified during surgery and the largest tumor diameter was measure on MRI axial plane on T2-CISS weighed images.

RESULTS

Preoperative amplitude asymmetry ratio was lower (n = 15, Mann-Whitney U test, p < 0.001) in the group with postoperative hearing preservation (n = 11) compared with the group with postoperative hearing preservation failure (n = 4). The positive predictive value of an AR less than 24% to assess postoperative hearing preservation is 91.6%. Tumor size and localization were not correlated with cVEMPs, nor with caloric testing in this group of small-sized intracanalicular vestibular schwannomas.

CONCLUSIONS

Our data suggest that cVEMPs may help predict hearing preservation outcome in vestibular schwannoma surgery via the middle fossa craniotomy approach.

Radiosurgery treatment is associated with improved facial nerve preservation versus repeat resection in recurrent vestibular schwannomas

BACKGROUND

Vestibular schwannomas (VSs) are benign neoplasms of the Schwann cells of cranial nerve VIII, and treatment of VS typically involves surgical resection. However, tumor recurrence may necessitate reintervention, and secondary treatment modalities include repeat surgical resection or adjuvant radiosurgery. The purpose of this study is to examine the scientific literature in order to determine whether surgical resection or radiosurgery for recurrent VS results in better tumor control, hearing preservation, and preservation of facial nerve function.

METHODS

The PubMed, Scopus, Embase, Cochrane, and Web of Science databases were searched for studies reporting on patients undergoing either radiosurgery or repeat surgical resection after primary surgical resection for recurrent VS. Statistical analyses were performed on the compiled data, primarily outcome data involving tumor control, hearing preservation, and preservation of facial nerve function.

RESULTS

We analyzed the data of 15 individual studies involving 359 total patients, and our results reveal that tumor control rates are comparable between adjuvant radiosurgery (91%, CI: 88-94%) and secondary resection (92%, CI 75-98%). However, adjuvant radiosurgery was shown to preserve good facial nerve function better (94%, CI 84-98%) compared to secondary surgical resection (56%, CI 41-69%).

CONCLUSION

With comparable tumor control rates and better preservation of good facial nerve function, this study suggests that secondary radiosurgery for recurrent VS is associated with both optimal tumor control and preservation of good facial nerve function.

Facial Nerve Paralysis Occurring 4 Days following Stereotactic Radiosurgery for a Vestibular Schwannoma

Stereotactic radiosurgery (SRS) is commonly used for the treatment of vestibular schwannomas given its high rate of tumor control and low rate of complications. Facial nerve palsy has been reported several months after treatment as a rare late complication of SRS. Here, we report a case of facial weakness occurring only 4 days after treatment and discuss potential etiology and management considerations.

Stereotactic Radiosurgery for Neurosurgical Patients: A Historical Review and Current Perspectives

Today, stereotactic radiosurgery is an effective therapy for a variety of intracranial pathology that were treated solely with open neurosurgery in the past. The technique was developed from the combination of therapeutic radiation and stereotactic devices for the precise localization of intracranial targets. Although stereotactic radiosurgery was originally performed as a partnership between neurosurgeons and radiation oncologists, this partnership has weakened in recent years, with some procedures being performed without neurosurgeons. At the same time, neurosurgeons across the United States and Canada have found their stereotactic radiosurgery training during residency inadequate. Although neurosurgeons, residency directors, and department chairs agree that stereotactic radiosurgery education and exposure during neurosurgery training could be improved, a limited number of resources exist for this kind of education. This review describes the history of stereotactic radiosurgery, assesses the state of its use and education today, and provides recommendations for the improvement of neurosurgical education in stereotactic radiosurgery for the future.

Translabyrinthine microsurgical resection of small vestibular schwannomas

OBJECTIVE

Translabyrinthine resection is one of a number of treatment options available to patients with vestibular schwannomas. Though this procedure is hearing destructive, the authors have noted excellent clinical outcomes for patients with small tumors. The authors review their experience at a tertiary acoustic neuroma referral center in using the translabyrinthine approach to resect small vestibular schwannomas. All operations were performed by a surgical team consisting of a single neurosurgeon and 1 of 7 neurotologists.

METHODS

Data from a prospectively maintained clinical database were extracted and reviewed. Consecutive patients with a preoperative diagnosis of vestibular schwannoma that had less than 1 cm of extension into the cerebellopontine angle, operated on between 2008 and 2013, were included. Patents with neurofibromatosis Type 2, previous treatment, or preexisting facial weakness were excluded. In total, 107 patients were identified, 74.7% of whom had poor hearing preoperatively.

RESULTS

Pathologically, 6.5% of patients were found to have a tumor other than vestibular schwannoma. Excluding two malignancies, the tumor control rates were 98.7%, as defined by absence of radiographic disease, and 99.0%, as defined by no need for additional treatment. Facial nerve outcome was normal (House-Brackmann Grade I) in 97.2% of patients and good (House-Brackmann Grade I–II) in 99.1%. Complications were cerebrospinal fluid leak (4.7%) and sigmoid sinus thrombosis (0.9%), none of which led to long-term sequelae.

CONCLUSIONS

Translabyrinthine resection of small vestibular schwannomas provides excellent results in terms of complication avoidance, tumor control, and facial nerve outcomes. This is a hearing-destructive operation that is advocated for selected patients.

Patterns of stereotactic radiotherapy utilization and fractionation for acoustic neuroma in the United States

OBJECTIVE

Stereotactic radiosurgery is a commonly offered modality utilized for the treatment of acoustic neuromas. In this study we sought to analyze the national practice patterns and utilization of GK compared to LINAC based radiosurgery.

METHODS

Patients diagnosed with an acoustic neuroma between 2004-2013 and treated with LINAC or GK radiosurgery in 1-5 fractions were identified in the National Cancer Database.

RESULTS

There were 2,705 patients analyzed, of which 2,222 (82.1%) received GK and 483 (17.9%) received LINAC based radiosurgery. Single fraction treatment was observed in 98.8% of GK patients, versus 19.5% of LINAC patients. LINAC based radiosurgery use increased from 3.5-3.7% in 2004-2005 to 15-26% from 2007-2013. On multivariable logistic regression the use of 3-5 fractions was strongly associated with LINAC based radiosurgery (p<0.001).

CONCLUSION

GK remains the predominant modality for delivering radiosurgery to acoustic neuroma. LINAC based radiosurgery is being cautiously adopted and often utilizes a hypofractionated approach.

Linear accelerator radiosurgery for vestibular schwannomas: Results of medium-term follow-up

BACKGROUND

To examine tumour control, via volume changes, and the complications of linear accelerator (LINAC)-based stereotactic radiosurgery (SRS) treatment of vestibular schwannomas (VSs) on medium-term follow-up.

METHODS

Between September 2003 and November 2009 fifty consecutive patients with VSs treated with SRS using a marginal dose of 12.5 Gy utilizing a LINAC equipped with a micro-multileaf collimator were identified. Evaluation included serial magnetic resonance imaging (MRI), and neurological and hearing examinations.

RESULTS

The median tumour volume at treatment was 2.4 (range: 0.24-10.59) cm3. The intracranial diameter of the tumours ranged between 7.7 and 28.7 (median: 15.8) mm. Follow-up MRI was available for analysis on 49 patients. The median radiological follow-up period was 5.8 (range: 1.4-9.2) years. The median tumour volume at last follow-up was 1.1 (range: 0.03-5.3) cm3. VS decreased in size in 45 (90%) patients, with a median reduction in tumour volume of 1.46 (range: 0.06-9.29) cm3 or a median tumour size reduction of 59% of the baseline (range: 6-90%) in these patients. VS remained stable in 2 patients and increased in size in 2 patients. Only 1 patient (2%) required additional intervention (surgery). 15 patients had useful hearing pre-treatment; 10 post-treatment pure-tone audiograms of these patients were available. 5 (50%) patients still had useful hearing post treatment. Non-auditory adverse radiation effects included new (House-Brackmann grade II) or worsened facial nerve palsy (House-Brackmann grade II to grade V) in 2 (4%) patients and trigeminal sensory disturbance in 2 (4%) patients.

CONCLUSIONS

At medium term, the vast majority of VSs treated with LINAC-based SRS exhibit tumour shrinkage. The slightly higher rate of facial nerve palsy compared with Gamma Knife surgery (GKS) results may be related to the learning curve. Other complications were similar to reported GKS results for VSs of comparable sizes.

Short-term therapeutic effects of low-dose cytarabine plus surgical resection on elderly patients with trigeminal nerve tumor and safety observation

OBJECTIVE

To evaluate the short-term therapeutic effects of low-dose cytarabine plus surgical resection on elderly patients with trigeminal nerve tumor and to observe the safety.

METHODS

A total of 120 elderly patients with trigeminal nerve tumor were divided into a treatment group and a control group by random draw (n=60), and both groups were subjected to resection by stereotactic image-guided endoscopic nasal surgery. Afterwards, the control group was administered with high-dose cytarabine while the treatment group was given low-dose cytarabine for 14 days.

RESULTS

Both groups completed treatment, but the effective rate of the treatment group (96.7%) was significantly higher than that of the control group (83.3%) (P < 0.05). The pain scores of the two groups were similar at T0, T1 and T2, but the score of the treatment group at T2 was significantly different from those at T0 and T1 (P < 0.05). During treatment, the treatment group was significantly less prone to complications such as headache, vomiting, vision impairment, nausea and local swelling than the control group (P < 0.05). During three months of follow-up, the appetite, sleep and daily living scores were significantly higher than those of the control group (P < 0.05).

CONCLUSION

Stereotactic image-guided surgery was able to treat trigeminal nerve tumor well, and the effect was enhanced by low-dose cytarabine that improved postoperative outcomes and quality of life by dramatically decreasing complications.

Critical appraisal of RapidArc radiosurgery with flattening filter free photon beams for benign brain lesions in comparison to GammaKnife: a treatment planning study

BACKGROUND

To evaluate the role of RapidArc (RA) for stereotactic radiosurgery (SRS) of benign brain lesions in comparison to GammaKnife (GK) based technique.

METHODS

Twelve patients with vestibular schwannoma (VS, n = 6) or cavernous sinus meningioma (CSM, n = 6) were planned for both SRS using volumetric modulated arc therapy (VMAT) by RA. 104 MV flattening filter free photon beams with a maximum dose rate of 2400 MU/min were selected. Data were compared against plans optimised for GK. A single dose of 12.5 Gy was prescribed. The primary objective was to assess treatment plan quality. Secondary aim was to appraise treatment efficiency.

RESULTS

For VS, comparing best GK vs. RA plans, homogeneity was 51.7 ± 3.5 vs. 6.4 ± 1.5%; Paddick conformity Index (PCI) resulted 0.81 ± 0.03 vs. 0.84 ± 0.04. Gradient index (PGI) was 2.7 ± 0.2 vs. 3.8 ± 0.6. Mean target dose was 17.1 ± 0.9 vs. 12.9 ± 0.1 Gy. For the brain stem, D(1cm3) was 5.1 ± 2.0 Gy vs 4.8 ± 1.6 Gy. For the ipsilateral cochlea, D(0.1cm3) was 1.7 ± 1.0 Gy vs. 1.8 ± 0.5 Gy. For CSM, homogeneity was 52.3 ± 2.4 vs. 12.4 ± 0.6; PCI: 0.86 ± 0.05 vs. 0.88 ± 0.05; PGI: 2.6 ± 0.1 vs. 3.8 ± 0.5; D(1cm3) to brain stem was 5.4 ± 2.8 Gy vs. 5.2 ± 2.8 Gy; D(0.1cm3) to ipsi-lateral optic nerve was 4.2 ± 2.1 vs. 2.1 ± 1.5 Gy; D(0.1cm3) to optic chiasm was 5.9 ± 3.1 vs. 4.5 ± 2.1 Gy. Treatment time was 53.7 ± 5.8 (64.9 ± 24.3) minutes for GK and 4.8 ± 1.3 (5.0 ± 0.7) minutes for RA for schwannomas (meningiomas).

CONCLUSIONS

SRS with RA and FFF beams revealed to be adequate and comparable to GK in terms of target coverage, homogeneity, organs at risk sparing with some gain in terms of treatment efficiency.