Spontaneous tumour shrinkage in 1261 observed patients with sporadic vestibular schwannoma

Documented Initial Growth Does Not Necessarily Indicate Treatment for Sporadic Vestibular Schwannomas

OBJECTIVE

To report the natural history of vestibular schwannoma (VS) who elected an initial period of observation and identify prognostic factors. To describe the natural history of growing VS, identify prognostic factors, and review the most recent literature.

STUDY DESIGN

Prospective cohort study and literature review.

SETTING

Tertiary referral center.

PATIENTS

Adult patients diagnosed with a VS between January 1998 and February 2023.

INTERVENTION

Magnetic resonance imaging surveillance.

MAIN OUTCOME MEASURES

Growth-free survival and subsequent growth-free survival considering significant growth as a change in size of ≥2 mm.

RESULTS

Of 430 patients undergoing observation with serial magnetic resonance imaging, 193 (44.9%) demonstrated significant growth at a median of 1.6 years (interquartile range, 0.94-3.51). Of the 193 patients who presented an initial episode of growth, 137 elected to continue to be observed. Of those, 83 (60.6%) presented a second episode of growth at a median of 1.43 years (interquartile range, 1.00-2.49). The subsequent growth-free survival rates (95% confidence interval) at 1, 3, 5, 7, and 10 years were 91.79% (87.26-96.56%), 64.44% (56.56-73.42%), 52.52% (44.23-62.35%), 42.23% (33.92-52.56%), and 36.11% (27.89-46.76%), respectively. Univariate and multivariate Cox regression analyses showed that EC tumor location and initial growth rate were significant predictors of subsequent growth.

CONCLUSIONS

Close observation after documentation of growth is an appropriate management in well-selected cases given that only around 56% of the tumor will continue to grow. Extracanalicular tumor location and initial growth rate are promising prognostic factors to help determine which patient would be a better candidate for close surveillance after initial documentation of growth.

Clinical practice guideline on the management of vestibular schwannoma

INTRODUCTION

Vestibular schwannoma (VS) is the most common tumour of the cerebellopontine angle. The greater accessibility to radiological tests has increased its diagnosis. Taking into account the characteristics of the tumour, the symptoms and the age of the patient, three therapeutic strategies have been proposed: observation, surgery or radiotherapy. Choosing the most appropriate for each patient is a frequent source of controversy.

MATERIAL AND METHODS

This paper includes an exhaustive literature review of issues related to VS that can serve as a clinical guide in the management of patients with these lesions. The presentation has been oriented in the form of questions that the clinician usually asks himself and the answers have been written and/or reviewed by a panel of national and international experts consulted by the Otology Commission of the SEORL-CCC.

RESULTS

A list has been compiled containing the 13 most controversial thematic blocks on the management of VS in the form of 50 questions, and answers to all of them have been sought through a systematic literature review (articles published on PubMed and Cochrane Library between 1992 and 2023 related to each thematic area). Thirty-three experts, led by the Otology Committee of SEORL-CCC, have analyzed and discussed all the answers. In Annex 1, 14 additional questions divided into 4 thematic areas can be found.

CONCLUSIONS

This clinical practice guideline on the management of VS offers agreed answers to the most common questions that are asked about this tumour. The absence of sufficient prospective studies means that the levels of evidence on the subject are generally medium or low. This fact increases the interest of this type of clinical practice guidelines prepared by experts.

Wait-and-scan management in sporadic Koos grade 4 vestibular schwannomas: A longitudinal volumetric study

Background

Volumetric natural history studies specifically on large vestibular schwannomas (VSs), commonly classified as Koos grade 4, are lacking. The aim of the current study is to present the volumetric tumor evolution in sporadic Koos grade 4 VSs and possible predictors for tumor growth.

Methods

Volumetric tumor measurements and tumor evolution patterns from serial MRI studies were analyzed from selected consecutive patients with Koos grade 4 VS undergoing initial wait-and-scan management between January 2001 and July 2020. The significant volumetric threshold was defined as a change in volume of ≥10%.

Results

Among 215 tumors with a median size (IQR) of 2.7 cm3 (1.8-4.2), 147 tumors (68%) demonstrated growth and 75 tumors (35%) demonstrated shrinkage during follow-up. Growth-free survival rates (95% CI) at 1, 2, 5, and 10 years were 55% (48-61), 36% (29-42), 29% (23-36), and 28% (21-34), respectively and did not significantly differ in tumors> 20 mm (Chi-square = .40; P-value = .53). Four tumor evolution patterns (% of total) were observed: continued growth (60); initial growth then shrinkage (7); continued shrinkage (27); and stability (5). Good hearing (adjusted HR 2.21, 95% CI 1.48-3.30; P < .001) and peritumoral edema (adjusted HR 2.22, 95% CI 1.18-4.13; P = .01) at diagnosis were significantly associated with an increased likelihood of growth.

Conclusions

Koos grade 4 VSs show a wide variety in size and growth. Due to variable growth patterns, an initial wait-and-scan strategy with short scan intervals may be an acceptable option in selected tumors, if no significant clinical symptoms of mass effect that warrant treatment are present.

Vestibular Impairment in Patients with Vestibular Schwannoma: A Journey through the Pitfalls of Current Literature

Vestibular Schwannoma is the most common tumour of Ponto Cerebellar Angle and is capable of strongly impacting the patient's quality of life. In recent decades, the proposals for the management of the disease have multiplied, just as the diagnostic capacity has improved. While in the past, the primary objective was the preservation of the facial function, and subsequently also of the auditory function, the attention to the vestibular symptomatology, which appears to be one of the main indicators of deterioration of quality of life, is still unsatisfactory. Many authors have tried to provide guidance on the best possible management strategy, but a universally recognized guideline is still lacking. This article offers an overview of the disease and the proposals which have advanced in the last twenty years, evaluating their qualities and defects in a critical reading.

Regression of Acoustic Tumor After Chemotherapy for Ovarian Cancer in a Patient With a Breast Cancer Susceptibility Gene 1 (BRCA1) Germline Mutation

We report the case of an adult woman who developed ovarian cancer during a follow-up for vestibular schwannoma. Volume reduction of the schwannoma was observed after chemotherapy for ovarian cancer. After ovarian cancer had been diagnosed, the patient was found to have a germline mutation of breast cancer susceptibility gene 1 (BRCA1). This is the first reported case of vestibular schwannoma in a patient with a germline mutation of BRCA1 and the first documented example of chemotherapy including olaparib to have shown efficacy for schwannoma.

Which Epidemiological Characteristics Drive Decision Making in the Management of Patients with Vestibular Schwannoma?

The incidence of sporadic vestibular schwannoma has significantly increased over the past few decades. However, there is no method currently available to accurately predict the risk of subsequent tumor growth. The difference in the management of five patient groups has been evaluated: wait and scan, conversion to microsurgery, conversion to stereoradiotherapy, sterioradiotherapy, and microsurgery. In total, 463 patients with vestibular schwannoma have been consulted in our department from 2010 through 2016. Of the 250 patients initially indicated for observation, 32.4% were later indicated for active treatment. Younger patients were more frequently indicated for surgery (mean age 48 years) compared to older patients, who were more often indicated for stereoradiotherapy (mean age 62 years). Tumor growth was observed more often in patients under 60 years of age and in patients with tumors greater than 10 mm. In elderly patients, including those with larger tumors, a conservative approach is the optimal solution. If tumor growth occurs in the wait-and-scan strategy, it is still possible to continue with a conservative approach in some situations. The duration of follow-up scans is still a matter of debate, as tumors can begin to grow after 5 years from the initial diagnosis.

Spontaneous regression of solid-cystic vestibular schwannoma: A case report

Background:

Vestibular schwannomas (VSs) are one of the most common tumors of the cerebellopontine angle and internal meatus, the evolution of this type of tumors is defined as unpredictable, it can enlarge or present a spontaneous regression as described in rare cases.

Case Description:

We report the case of a 50-year-old woman who presented with a large right full cystic VS revealed by a balance disorder associated with deafness in the right ear which spontaneously regressed. The patient was lost to follow-up for 3 years, the symptomatology improved, and the tumor clearly regressed without any surgical treatment.

Conclusion:

Spontaneous regression of solid-cystic VS is possible but rare, it can be part of conservative treatment, which requires regular follow-up.

Vestibular schwannomas with spontaneous shrinkage: about 35 cases

PURPOSES

The first aim is to describe the epidemiological, clinical, and radiological characteristics of regressive vestibular schwannomas (VS), based on volumetric measurements on MRI to define which regressions are significant. The secondary aim is to look for a correlation between a shrinkage of the tumor and the medical history, and the presence of clinical symptoms.

METHODS

We first selected all patients presenting with a VS who underwent two or more MRI of the internal auditory canal on the same 3 T MRI machine retrospectively between January 2013 and June 2018. All MRI images were evaluated independently by two radiologists. The volumetric analysis was performed contrast-enhanced 2D spin-echo T1-weighted sequence and expressed in cubic centimeters.

RESULTS

Thirty-five patients presented with a regressive VS on MRI (14%). The annual mean shrinkage rate was 0.08 cm³/year. Eighty percent of the patients present both a shrinkage by more than 0.01 cm³/year and a decrease of the initial tumor volume by more than 20%. The majority of patients are asymptomatic or presented moderate balance disorders, which remained stable or improved over time. Tinnitus was observed in 47% and was stable or improved in the majority of cases and the mean annual mean hearing loss was by < or = 4 dB/year.

CONCLUSION

Out of 247 VS, 14% decreased using follow-up (by > or = 2 MRI), and a spontaneous shrinkage greater than 0.01 cm³/year and greater than 20% could be considered significant.

The role of a virtual telephone clinic in the follow-up management of lateral skull base tumours

OBJECTIVE

The purpose of this article was to determine the impact of employing a telephone clinic for follow-up of patients with stable lateral skull-base tumours.

METHOD

An analysis of 1515 patients in the national lateral skull-base service was performed, and 148 patients enrolled in the telephone clinic to date were identified. The length of time that patients waited for results of their follow-up scans and the travel distance saved by patients not having to attend the hospital for their results was determined.

RESULTS

The mean time from scan to receiving results was 30.5 ± 32 days, 14 days sooner than in the face-to-face group (p = 0.0016). The average round-trip distance travelled by patients to the hospital for results of their scans was 256 ± 131 km.

CONCLUSION

The telephone clinic led to a significant reduction in time until patients received their scan results and helped reduce travel distance and clinic numbers in traditional face-to-face clinics.

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.

Tracking Spontaneous Vestibular Schwannoma Regression with Volumetric Measurements

OBJECTIVE

To characterize a series of patients with MRI evidence of spontaneous vestibular schwannoma (VS) regression.

STUDY DESIGN

Retrospective case series.

METHODS

Retrospective review between 2012 and 2020 from a single, tertiary-care center of all patients with an untreated, sporadic VS and spontaneous regression in volumetric tumor size over the course of observation. The main outcome measures included VS size and location, presenting symptoms, medication use, changes in pure-tone averages and word recognition scores.

RESULTS

The 13 treatment-naïve patients (62% female, mean age 67.1 years) with spontaneous VS regression represented 3.9% of all patients undergoing observation with serial imaging during the study period. Median tumor size from initial MRI was 529.0 mm³ (range: 108 mm³ -13,180 mm³ ). The mean interval between MRI measurements was 5.5 years (SD 4.4 years). The average percent decrease in tumor size was 36.1% (SD 21.9%) and the average rate of volume decrease was 15.8 mm³ /yr (SD 25.4 mm³ /yr). Five patients were classified as having major regression, defined by a relative decrease in volume of >40%, while eight patients had minor regression (<40% relative volume reduction). No significant differences in initial tumor size, rate of regression, or audiometric changes were observed between the major and minor regression cohorts.

CONCLUSIONS

Patients with evidence of a spontaneously shrinking VS have a heterogeneous presentation. Due to the scarcity of this phenomenon, predicting which tumors will eventually undergo regression remains unclear. Employing volumetric measurements to compare serial MRI scans may improve the accuracy of detecting shrinking tumors.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E1647-E1652, 2021.

Postoperative Hearing Preservation in Patients Undergoing Retrosigmoid Craniotomy for Resection of Vestibular Schwannomas: A Systematic Review of 2034 Patients

BACKGROUND

Vestibular schwannomas (VS) are benign tumors derived from Schwann cells ensheathing the vestibulocochlear nerve. The retrosigmoid (RS) surgical approach is useful to resect tumors of multiple sizes while affording the possibility of preserving postoperative hearing.

OBJECTIVE

To conduct a systematic review of published literature investigating hearing preservation rates in patients who underwent the RS approach for VS treatment.

METHODS

The PubMed, Scopus, and Embase databases were surveyed for studies that reported preoperative and postoperative hearing grades on VS patients who underwent RS treatment. Hearing preservation rates were calculated, and additional patient demographic data were extracted. Tumor size data were stratified to compare hearing preservation rates after surgery for intracanalicular, small (0-20 mm), and large (>20 mm) tumors.

RESULTS

Of 383 deduplicated articles, 26 studies (6.8%) met eligibility criteria for a total of 2034 patients with serviceable preoperative hearing, for whom postoperative hearing status was evaluated. Aggregate hearing preservation was 31% and 35% under a fixed and random effects model, respectively. A mixed effects model was used to determine hearing preservation rates depending on tumor size, which were determined to be 57%, 37%, and 12% for intracanalicular, small, and large tumors, respectively. Significant cross-study heterogeneity was found (I2 = 93%, τ2 = .964, P < .01; Q = 287.80, P = < .001), with rates of hearing preservation ranging from 0% to 100%.

CONCLUSION

Tumor size may have an effect on hearing preservation rates, but multiple factors should be considered. Discussion of a patient's expectations for hearing preservation is critical when deciding on VS treatment plans.

Radiologic Features of Spontaneous Regression of Vestibular Schwannomas

BACKGROUND

Vestibular schwannoma (VS) is the most common benign tumor originating in the cerebellopontine angle. In most cases, tumors tend to grow and deserve proper treatment. Sometimes they stabilize, and rarely they decrease in size spontaneously.

METHODS

We evaluated retrospectively the images of patients with spontaneous tumor regression. We describe the common neuroimage findings of patients with spontaneous tumoral regression.

RESULTS

Four patients with diagnosis of VS were followed with magnetic resonance imaging (MRI). There were some relevant features in MRI: a heterogeneous contrast enhancement in the outer layer of the tumor and presence of a cerebrospinal fluid column between the tumor and the entrance of the internal auditory canal. The percentage of tumor diameter reduction ranged from 20% to 40%.

CONCLUSIONS

Some MRI features may demonstrate a spontaneous involution of VS and may be closely followed in asymptomatic or oligosymptomatic patients.

How to radiologically identify a spontaneous regression of sporadic vestibular schwannoma?

Background

The natural history of sporadic vestibular schwannoma is unpredictable, with tumors growing, non-growing and even showing spontaneous regression in some rare cases.

Objective

This retrospective study aims to describe the radiologic signs characterizing and identifying the shrinking vestibular schwannoma.

Methods

Involution was considered to have occurred if tumor size had decreased by 2 mm or more on its largest diameter. All magnetic resonance imaging scans were reviewed for tumor size, internal auditory meatus size, and tumor characteristics. Volumetric measurements were performed on the first and last scan. Audiometric data were collected at the first and last visit.

Results

Fourteen patients with a confirmed spontaneous regression were included, with a mean follow-up of 5 ± 2.6 years. The mean shrinkage rate was 0.9 ± 0.59 mm/year on 2D measurements, and 0.2 ± 0.17 cm³/year on volumetric measurements, with a relative shrinkage of 40 ± 16.9%. Two remarkable radiologic features were observed: First, a festooned aspect, defined by multiple curves in the tumor outline, noticed in 12 cases (86%); second, the appearance of cerebrospinal fluid filling the internal auditory meatus, associated with an enlargement of the internal auditory meatus compared to the contralateral side, and observed in 10 out of 13 cases with internal auditory meatus invasion (77%). Those two aspects were associated in 64% of cases.

Conclusion

These two newly reported radiologic features could help neurosurgeons, oto-neurosurgeons and neuroradiologists to identify a spontaneous vestibular schwannoma involution at first visit. This could allow any treatment to be postponed, monitoring to be more widely spaced, and patients to be reassured.

Age-dependent copy number variations of TP53 tumour suppressor gene associated with altered phosphorylation status of p53 protein in sporadic schwannomas

PURPOSE

Point mutations of TP53 tumour suppressor are very rare in schwannomas. We aim to characterize the frequency of exonic copy-number changes of the gene in the tumour and to examine the association between TP53 alterations, phosphorylation status of p53 protein and clinical phenotypes.

METHODS

The alterations of TP53 were screened by a combination of Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA) in a total of 44 vestibular schwannomas. The mutation index (MI) in a tumour was defined as the number of exons mutated/ the number of exons tested. Phosphorylation status of p53 protein was investigated by immunoblotting and immunofluorescence.

RESULTS

MLPA analysis showed single and multi-exon deletion mutations of TP53 in 65.7% of the cases. Comparisons of clinical features between mutated and non-mutated patients established an association of TP53 mutations with progressive phenotypes, including an earlier formation and a larger tumour. In addition, there were significant correlations between MI and both patients' age and tumour size. The Ser 392 phosphorylation level of p53 varied among tumours, and correlation analysis revealed an age-dependent phosphorylation pattern. The majority of tumours with hyperphosphorylated p53 were from mutated and young patients, suggesting an association of Ser392 phosphorylation with the mutational status of TP53 involved in the acceleration of tumour growth in young individuals. Moreover, Ser 392 phosphorylation contributed to a nuclear accumulation of p53 in schwannona cultures with TP53 mutation.

CONCLUSIONS

An interplay between the mutation status of TP53, phosphorylation patterns and tumour behaviors might be established in the disease.

Complications in translabyrinthine surgery of vestibular schwannoma

OBJECTIVE

To evaluate the risk of complications associated with tumor size and patient's age in translabyrinthine vestibular schwannoma surgery.

METHODS

700 patients with vestibular schwannoma primarily underwent translabyrinthine surgery between 1988 and 2014. Pre- and postoperative data were collected in a database and incidence of the postoperative complications cerebrospinal fluid leakage, meningitis, intracranial hemorrhage (ICH), facial nerve function and mortality were assessed and related to the tumor size and patient's age and retrospectively evaluated.

RESULTS

The tumor size significantly influenced the incidence of ICH and facial nerve dysfunction whereas age was correlated to facial nerve outcome.

CONCLUSIONS

The translabyrinthine approach is a safe surgical procedure with relatively low risks of complications. The tumor size was significantly associated with a higher risk of ICH and facial nerve dysfunction whereas age only influenced the facial nerve outcome.

"Wait and scan" management of patients with vestibular schwannoma and the relevance of non-contrast MRI in the follow-up

Vestibular schwannoma (VS) is a slow-growing benign neoplasm. There has been an evolution in the management of VS from active treatments (microsurgery and stereotactic radiotherapy) to conservative management (wait and scan). Regular MRI scanning is necessary to monitor tumor progression. Conservative management causes significantly less complications and offers a higher quality of life compared with active treatments. The mean growth rate of VS varies from 0.4 to 2.9 mm/year, and spontaneous shrinkage is observed in 3.8 percent of tumors during observation. If significant growth occurs, active treatment is considered. Significant growth is defined as an increase of at least 3 mm in the largest extrameatal diameter in any plane between the first and last available scans. The vestibulocochlear nerve is surrounded by cerebrospinal fluid, which provides natural contrast for MRI; thus, gadolinium may not be needed to detect VS. Specific sequences have high sensitivity, specificity, and accuracy for detection of progression. Hypointense signal in the ipsilateral inner ear fluid might be a useful sign to distinguish VS from meningioma. In this paper, we summarize the current status of research on conservative management and non-contrast MRI for the detection of VS.

Differential NF2 Gene Status in Sporadic Vestibular Schwannomas and its Prognostic Impact on Tumour Growth Patterns

The great majority of sporadic vestibular schwannomas (VSs) are due to the inactivation of the NF2 gene. In this study, we found age-dependent differences in the clinical parameters of sporadic VSs. Young patients were characterized by progressive tumour behaviours, including earlier onset of initial symptoms, shorter symptom duration and larger tumour size. An increased rate of "two-hits" of both NF2 alleles, usually by mutation and allelic loss, was observed in young cases compared to older, and this correlated with the loss of protein and mRNA expression. In contrast, the tumours with a single mutation (referred to as 'one-hit') exhibited obvious expression levels. Moreover, a mixture of merlin-expressing tumour cells and non-expressing tumour cells was observed in 'one-hit' schwannomas, suggesting that a subset of 'one-hit' tumour cells was present in these tumours. To mimic the growth promoting effects by the second hit, we performed lentivirus-mediated NF2 knockdown in the 'one-hit' schwannoma cultures. Following the loss of NF2 expression, schwannoma cultures demonstrated increased proliferation rates. Above all, we have identified a correlation between the NF2 status and the growth patterns of sporadic VSs. The treatment decision-making, microsurgery or "wait and scan" strategy, should be carried out according to the tumour's genetic background.

Differential NF2 Gene Status in Sporadic Vestibular Schwannomas and its Prognostic Impact on Tumour Growth Patterns

The great majority of sporadic vestibular schwannomas (VSs) are due to the inactivation of the NF2 gene. In this study, we found age-dependent differences in the clinical parameters of sporadic VSs. Young patients were characterized by progressive tumour behaviours, including earlier onset of initial symptoms, shorter symptom duration and larger tumour size. An increased rate of “two-hits” of both NF2 alleles, usually by mutation and allelic loss, was observed in young cases compared to older, and this correlated with the loss of protein and mRNA expression. In contrast, the tumours with a single mutation (referred to as ‘one-hit’) exhibited obvious expression levels. Moreover, a mixture of merlin-expressing tumour cells and non-expressing tumour cells was observed in ‘one-hit’ schwannomas, suggesting that a subset of ‘one-hit’ tumour cells was present in these tumours. To mimic the growth promoting effects by the second hit, we performed lentivirus-mediated NF2 knockdown in the ‘one-hit’ schwannoma cultures. Following the loss of NF2 expression, schwannoma cultures demonstrated increased proliferation rates. Above all, we have identified a correlation between the NF2 status and the growth patterns of sporadic VSs. The treatment decision-making, microsurgery or “wait and scan” strategy, should be carried out according to the tumour’s genetic background.

Long-term follow-up after stereotactic radiosurgery of intracanalicular acoustic neurinoma

Background

The management of solely intracanalicular acoustic neurinoma (iAN) includes observation, microsurgical resection and radiation therapy. Treatment goals are long-term tumor control, hearing preservation and concurrently low side-effects. Stereotactic radiosurgery (SRS) has evolved as an alternative first-line treatment for small AN. Here we report about the long-term follow-up of a unique cohort of patients with iAN after LINAC or Cyberknife® based SRS.

Methods

In this single center retrospective analysis, we included all patients with iAN who underwent single session LINAC or Cyberknife® based SRS between 1993 and 2015, and who had a minimum follow-up period of six weeks. Patient data were analyzed in terms of radiological and clinical tumor control (no further treatment necessary), subjective preservation of serviceable hearing, objective change in pure tone averages (PTA), and adverse events rated by the Common Terminology Criteria for Adverse Events (CTCAE; v4.03).

Results

Forty-nine patients (f/m = 21/28, median age 54 ± 12, range 20–77 years) were identified. Mean tumor volumes were 0.24 ± 0.12 cm³ (range, 0.1–0.68 cm³), the mean marginal dose was 12.6 ± 0.6 Gy (range, 11.0–14.0 Gy) and the prescription isodose was 75 ± 7.4% (range, 47–86%). Mean follow-up time was 65 months (range, 4–239 months).

Radiological tumor control was 100% during further follow-up. 17 (35%) out of 49 patients had lost serviceable hearing prior to SRS. Those with preserved serviceable hearing remained stable in 78% (n = 25/32) at the last follow-up (LFU). The median PTA (n = 16) increased from 25.6 dB prior to SRS to 43.8 dB at LFU.

Mild adverse events were observed temporarily in two patients (4%): one with CTCAE grade 1 facial nerve disorder after 3 months, resolving three months later, and one with CTCAE grade 2 facial muscle weakness resolving after 12 months. Three patients described permanent mild symptoms CTCAE grade 1 without limiting daily life (facial weakness n = 1, vertigo n = 2).

Conclusion

SRS for iAN shows long-term reliable tumor control with a high rate of hearing preservation without considerable permanent side effects, and can be proposed as a safe and effective treatment alternative to microsurgical resection.

Spontaneous regression of a parafalcine meningioma in a multiple sclerosis patient being treated with interferon beta-1a

Regression of meningioma after haemorrhage and the cessation of hormone treatment is well reported. However, spontaneous regression is very rarely observed. Here, we report the spontaneous regression of a parafalcine meningioma in a 56-year-old woman with multiple sclerosis, who was referred to our department after an incidental finding on magnetic resonance imaging. She was being treated with interferon beta-1a to manage the symptoms. To our knowledge, this is the first report of spontaneous regression of meningioma in a patient receiving interferon beta-1a therapy and just the second report of spontaneous regression in general.

Spontaneous shrinkage of vestibular schwannoma

Background:

“Watch, wait, and rescan” (WWR) has an established place as a successful management option for a significant proportion of vestibular schwannomas (VS) as an alternative to microsurgical removal or stereotactic radiotherapy. VS may grow slowly and continuously, followed by stagnation or even shrinkage. We present two case reports of spontaneous shrinkage of VS along with a review of the literature.

Case Description:

A 29-year-old female presented with a progressive history of visual blurring and intermittent diplopia over 2 months. A 29 mm of maximum intracranial diameter (ICD) VS with secondary obstructive hydrocephalus was diagnosed. The patient underwent a ventriculo-peritoneal shunt with resolution of her symptoms and opted for initial WWR management. Interval scanning between 2007 and 2014 showed progressive reduction in the maximum ICD together with reduction in the degree of central tumor enhancement. Maximum ICD at most recent follow up was 22 mm. A 28-year-old female was referred with right sensorineural deafness. A right VS of maximum ICD of 27 mm was diagnosed. Initial WWR management was planned after discussion. Serial imaging showed an initial increase in the size of the tumor followed by progressive reduction in size. The most recent follow up showed a maximum ICD of 20 mm.

Conclusion:

Early WWR management can be associated with spontaneous shrinkage of VS over time. Prospective clinical study of larger numbers of such cases using the UK VS database may help to identify predictive factors for the spontaneous regression of VS.

Vestibular Schwannoma: The Evolution of Hearing and Tumor Size in Natural Course and after Treatment by LINAC Stereotactic Radiosurgery

OBJECTIVE

To review the natural course of tumor size and hearing during conservative management of 151 patients with unilateral vestibular schwannoma (VS), and to evaluate the same parameters for the part of the group (n = 84) who were treated by LINAC stereotactic radiosurgery (SRS).

METHODS

In prospectively collected data, patients underwent MRI and complete audiovestibular tests at inclusion, during the conservative management period and after SRS. Hearing was graded according to the Gardner-Robertson (GR) scale and tumor size according to Koos. Statistics were performed using Kaplan-Meier survival analysis and multivariate analyses including linear and logistic regression. Specific insight was given to patients with serviceable hearing.

RESULTS

During the conservative management period (mean follow-up time: 24 months, range: 6-96), the annual risk of GR class degradation was 6% for GRI and 15% for GR II patients. Hearing loss as an initial symptom was highly predictive of further hearing loss (p = 0.003). Tumor growth reached 25%. For SRS patients, functional hearing preservation was 51% at 1 year and 36% at 3 years. Tumor control was 94 and 91%, respectively.

CONCLUSION

In VS patients, hearing loss at the time of diagnosis is a predictor of poorer hearing outcome. LINAC SRS is efficient for tumor control. Patients who preserved their pretreatment hearing presented less hearing loss per year after SRS than before treatment, suggesting a protective effect of SRS when cochlear function can be preserved.

Spontaneous regression together with increased calcification of incidental meningioma

BACKGROUND

Regression of meningioma has been reported after hemorrhage or hormonal withdrawal. However, meningioma regression is rarely observed spontaneously.

CASE DESCRIPTION

A right falx meningioma was incidentally diagnosed and was followed at every one-year by magnetic resonance imaging (MRI) for over 7 years. The tumor, with a maximum diameter of 4 cm, showed a slightly high density and was enhanced on computed tomography (CT), and a high intensity with a low-intensity core on T2 MRI, with significant edema. The meningioma gradually shrank together with a decrease of edema and increase of calcification. The initial volume, 25.5 cm(3), regressed linearly to less than half, 9.9 cm(3).

CONCLUSION

Here, we report a case of an incidentally diagnosed meningioma that regressed spontaneously. The pattern of the regression was similar to that following gamma knife radiosurgery.