Medium-sized Vestibular Schwannomas Research Articles

Prognostic Factors of Long-Term Hearing Preservation in Small and Medium-Sized Vestibular Schwannomas After Microsurgery.

The authors evaluated the long-term hearing outcomes of patients with vestibular schwannoma (VS) to explore appropriate surgical treatment. Retrospective study. Tertiary referral center. A total of 138 patients diagnosed with small and medium-sized VS with serviceable hearing from January 2006 to December 2015. All patients underwent microsurgery via retrosigmoid (RSA) or middle cranial fossa approach (MFA) and were followed up for over 2 years. Pre- and postoperative hearing, including pure tone audiometry, speech discrimination score, and auditory brainstem response (ABR), were analyzed. The mean tumor size and volume were 16.6 ± 3.4 mm and 1711.8 ± 918.5 mm, respectively. Preoperative hearing levels were Class A in 42, Class B in 67, and Class C in 29 patients. Patients with a tumor from the superior vestibular nerve (SVN) had better hearing at diagnosis. Postoperative hearing levels were Class A, B, C, and D for 28, 17, 32, and 61 patients. Hearing outcomes were significantly better in patients with normal intraoperative I wave on ABR. Hearing loss within 6 months had a positive effect on postoperative hearing. Better preoperative hearing and tumors from SVN were correlated with better postoperative hearing outcomes. Tumor size, cystic variation, or extension to the fundus of internal auditory canal had no influence on hearing preservation. Better preoperative hearing, shorter hearing loss period, tumors from SVN, and normal intraoperative I wave are prognostic factors for serviceable hearing. RSA and MFA are effective and safe for tumor removal and hearing preservation.

Retrosigmoid Approach for Resection of Medium-Sized Vestibular Schwannoma.

Objectives This video was aimed to describe the relevant anatomy and key surgical steps of retrosigmoid approach for gross total resection of a medium-sized vestibular schwannoma (VS). Design The procedure is described in a surgical instructional video. Setting The surgery took place at a tertiary skull base referral center. Participant Patient is a 63-year-old woman who reported with nonserviceable hearing (Pure Tone Average 60 dB Hearing level, Word Recognition Score 45%), occasional tinnitus, and a VS in the left cerebellopontine angle (CPA), extending into internal auditory canal (IAC), measuring 1.7 cm parallel to the petrous temporal bone. Main Outcome Measures The VS was resected by retrosigmoid approach. Results The surgery results gross total resection of the VS with postoperative House–Brackmann grade 1 facial nerve function and no postoperative complications. Conclusion The retrosigmoid approach is a good strategy to remove VS involving the CPA and the IAC. The link to the video can be found at: https://youtu.be/B6K_UkrKitg .

When Should We Stop Scanning Older Patients with Vestibular Schwannomas?

Objective Observation is a well-accepted management for small- to medium-sized vestibular schwannomas (VSs). Although there are good data on the natural history of this disease within adults, no studies have looked specifically at those aged over 70 years. Thus, there is a need for a surveillance protocol to determine if and when we can stop imaging safely patients aged 70 years and over with a new diagnosis of VSs when managed with observation. Design Over a 13-year period, we retrospectively analyzed all skull base unit patients with a sporadic unilateral VSs managed with an imaging surveillance protocol. All data were collected prospectively with a minimum follow-up of 5 years. Setting Tertiary referral skull base unit Participants Patients aged 70 years and over with sporadic VSs at diagnosis Main Outcome Measures Main outcome measures Results A total of 112 patients met inclusion criteria. The median age at diagnosis was 74 years (range: 70-87 years). The mean follow-up was 82 months (range: 60-144). The size of the VSs at diagnosis was intracanalicular (IC) in 46%, small in 41%, medium in 12%, and large in 2%. Growth was more likely where tumors were extracanalicular (EC) rather than IC at presentation ( p = 0.036) and within the first 18 months after diagnosis ( p < 0.001). Twenty-nine percent of VSs displayed growth (6% continued surveillance, 23% received active treatment). Good hearing at diagnosis did not predict tumor stability for IC or EC tumors ( p = 0.162 and p = 0.536). Conclusions Since no VSs grew after 42 months from diagnosis, our data support an initial magnetic resonance imaging (MRI) at 6 months after diagnosis followed by an annual MRI for 3 years. At this point, consideration could be given to discussing discontinuation or further imaging with patients.

Early magnetic resonance image volumetric changes of vestibular schwannoma after Gamma Knife radiosurgery: a prospective study of 18 cases

BackgroundGamma Knife radiosurgery is the principal alternative to microsurgical resection for acoustic neuromas (vestibular schwannomas). However; its increasing use worldwide and evolution of Gamma Knife device precision and safety had led to its acceptance as primary management for small- and medium-sized vestibular schwannomas. We tried to evaluate the tumor volume changes that occur with these tumors following Gamma Knife radiosurgery.MethodsEighteen patients with stereotactic radiosurgery with Gamma Knife through the year 2016 completed 1-year MRI follow-up at the 3rd, 6th, and 12th month after the Gamma Knife treatment. All the patients had unilateral vestibular schwannomas; the mean dose of radiation to the tumors was 12 Gy (range 10–14 Gy). Post treatment imaging was done with a high-resolution 3 T MRI scanner. Tumor sizes are calculated by using Onis software.ResultsFour patterns of volumetric changes were noticed. Most of the tumors increased in size on the third month follow-up MRI (89%); 15 (83%) tumors on the sixth month returned to their initial pre-Gamma Knife radiosurgery (PGKR) sizes. On the last (12th month) follow-up MRI with tumor sizes compared to initial PGKR sizes, 8 (44%) tumors showed no change, 6 (33%) tumors became smaller, and 4 (22%) tumors increase in size. Tumor control rate was 78% for the first year after Gamma Knife radiosurgery.ConclusionsThe third month follow-up MR images are practically not informative and might lead to unnecessary intervention; sixth month follow-up MR images are a crucial point and they may predict tumor behavior. Age, gender, and Koos stage whether stage II or III are not affecting tumor control. Gamma Knife radiosurgery is an effective intervention for Koos II and Koos III vestibular schwannomas.

Gamma Knife radiosurgery for large vestibular schwannomas greater than 3 cm in diameter.

OBJECTIVE Stereotactic radiosurgery (SRS) is an important alternative management option for patients with small- and medium-sized vestibular schwannomas (VSs). Its use in the treatment of large tumors, however, is still being debated. The authors reviewed their recent experience to assess the potential role of SRS in larger-sized VSs. METHODS Between 2000 and 2014, 35 patients with large VSs, defined as having both a single dimension > 3 cm and a volume > 10 cm3, underwent Gamma Knife radiosurgery (GKRS). Nine patients (25.7%) had previously undergone resection. The median total volume covered in this group of patients was 14.8 cm3 (range 10.3-24.5 cm3). The median tumor margin dose was 11 Gy (range 10-12 Gy). RESULTS The median follow-up duration was 48 months (range 6-156 months). All 35 patients had regular MRI follow-up examinations. Twenty tumors (57.1%) had a volume reduction of greater than 50%, 5 (14.3%) had a volume reduction of 15%-50%, 5 (14.3%) were stable in size (volume change < 15%), and 5 (14.3%) had larger volumes (all of these lesions were eventually resected). Four patients (11.4%) underwent resection within 9 months to 6 years because of progressive symptoms. One patient (2.9%) had open surgery for new-onset intractable trigeminal neuralgia at 48 months after GKRS. Two patients (5.7%) who developed a symptomatic cyst underwent placement of a cystoperitoneal shunt. Eight (66%) of 12 patients with pre-GKRS trigeminal sensory dysfunction had hypoesthesia relief. One hemifacial spasm completely resolved 3 years after treatment. Seven patients with facial weakness experienced no deterioration after GKRS. Two of 3 patients with serviceable hearing before GKRS deteriorated while 1 patient retained the same level of hearing. Two patients improved from severe hearing loss to pure tone audiometry less than 50 dB. The authors found borderline statistical significance for post-GKRS tumor enlargement for later resection (p = 0.05, HR 9.97, CI 0.99-100.00). A tumor volume ≥ 15 cm3 was a significant factor predictive of GKRS failure (p = 0.005). No difference in outcome was observed based on indication for GKRS (p = 0.0761). CONCLUSIONS Although microsurgical resection remains the primary management choice in patients with VSs, most VSs that are defined as having both a single dimension > 3 cm and a volume > 10 cm3 and tolerable mass effect can be managed satisfactorily with GKRS. Tumor volume ≥ 15 cm3 is a significant factor predicting poor tumor control following GKRS.

Radiosurgery for vestibular schwannomas

Vestibular schwannomas (VS) are benign tumours arising from the 8 th cranial nerve. There are various treatment options for these tumours, which depend upon the tumour size and patient age. However, the surgical treatment has been the conventional method of management of these tumours, since they are frequently detected when quite large in size, especially in our country. Gamma knife radiosurgery (GKRS) is frequently reserved for young patients with small and medium-sized VS (

Patient- versus physician-reported facial disability in vestibular schwannoma: an international cross-sectional study.

OBJECTIVE Patient-reported outcomes are increasingly used in studies of vestibular schwannoma (VS); however, few studies have examined self-evaluated facial nerve function and its relation to physician-reported outcomes. The primary objective of this study was to compare patient self-evaluations of facial disability with physician-evaluated facial nerve status and with self-evaluations of a healthy control group. The second objective was to provide insight into the controversial subject of the optimal initial management of small- and medium-sized VSs; consequently, the authors compared patient-reported facial nerve disability following treatment via observation (OBS), Gamma Knife surgery (GKS), or microsurgery (MS). Lastly, the authors sought to identify risk factors for facial nerve dysfunction following treatment for small- and medium-sized VSs. METHODS All patients with a VS 3 cm or smaller that was singly treated with OBS, GKS, or MS at either of 2 independent treatment centers between 1998 and 2008 were retrospectively identified. Longitudinal facial nerve measures and clinical data, including facial nerve evaluation according to the House-Brackmann (HB) grading system, were extracted from existing VS databases. Supplementing the objective data were Facial Disability Index (FDI) scores, which were obtained via survey of patients a mean of 7.7 years after initial treatment. RESULTS The response rate among the 682 eligible patients was 79%; thus, data from a total of 539 patients were analyzed. One hundred forty-eight patients had been managed by OBS, 247 with GKS, and 144 with MS. Patients who underwent microsurgery had larger tumors and were younger than those who underwent OBS or GKS. Overall, facial nerve outcomes were satisfactory following treatment, with more than 90% of patients having HB Grade I function at the last clinical follow-up. Treatment was the major risk factor for facial nerve dysfunction. Almost one-fifth of the patients treated with MS had an objective decline in facial nerve function, whereas only 2% in the GKS group and 0% in the OBS cohort had a decline. The physical subscale of the FDI in the VS patients was highly associated with HB grade; however, the social/well-being subscale of the FDI was not. Thus, any social disability caused by facial palsy was not detectable by use of this questionnaire. CONCLUSIONS The majority of patients with small- and medium-sized VSs attain excellent long-term facial nerve function and low facial nerve disability regardless of treatment modality. Tumor size and microsurgical treatment are risk factors for facial nerve dysfunction and self-reported disability. The FDI questionnaire is sensitive to the physical but not the social impairment associated with facial dysfunction.

Stereotactic radiosurgery for vestibular schwannomas: average 10-year follow-up results focusing on long-term hearing preservation.

OBJECTIVE The aim of this study was to reappraise long-term treatment outcomes of stereotactic radiosurgery (SRS) for vestibular schwannomas (VSs). The authors used a database that included patients who underwent SRS with a unique dose-planning technique, i.e., partial tumor coverage designed to avoid excess irradiation of the facial and cochlear nerves, focusing on tumor control and hearing preservation. Clinical factors associated with post-SRS tumor control and long-term hearing preservation were also analyzed. METHODS This institutional review board-approved, retrospective cohort study used the authors' prospectively accumulated database. Among 207 patients who underwent Gamma Knife SRS for VSs between 1990 and 2005, 183 (who were followed up for at least 36 post-SRS months) were studied. The median tumor volume was 2.0 cm3 (range 0.05-26.2 cm3). The median prescribed dose at the tumor periphery was 12.0 Gy (range 8.8-15.0 Gy; 12.0 Gy was used in 171 patients [93%]), whereas tumor portions facing the facial and cochlear nerves were irradiated with 10.0 Gy. As a result, 72%-99% of each tumor was irradiated with the prescribed dose. The mean cochlear doses ranged from 2.3 to 5.7 Gy (median 4.1 Gy). RESULTS The median durations of imaging and audiometric follow-up were 114 months (interquartile range 73-144 months) and 59 months (interquartile range 33-109 months), respectively. Tumor shrinkage was documented in 110 (61%), no change in 48 (27%), and enlargement in the other 22 (12%) patients. A further procedure (FP) was required in 15 (8%) patients. Thus, the tumor growth control rate was 88% and the clinical control rate (i.e., no need for an FP) was 92%. The cumulative FP-free rates were 96%, 93%, and 87% at the 60th, 120th, and 180th post-SRS month, respectively. Six (3%) patients experienced facial pain, and 2 developed transient facial palsy. Serviceable hearing was defined as a pure tone audiogram result better than 50 dB. Among the 66 patients with serviceable hearing before SRS who were followed up, hearing acuity was preserved in 23 (35%). Actuarial serviceable hearing preservation rates were 49%, 24%, and 12% at the 60th, 120th, and 180th post-SRS month, respectively. On univariable analysis, only cystic-type tumor (HR 3.36, 95% CI 1.18-9.36; p = 0.02) was shown to have a significantly unfavorable association with FP. Multivariable analysis followed by univariable analysis revealed that higher age (≥ 65 years: HR 2.66, 95% CI 1.16-5.92; p = 0.02), larger tumor volume (≥ 8 cm3: HR 5.36, 95% CI 1.20-17.4; p = 0.03), and higher cochlear dose (mean cochlear dose > 4.2 Gy: HR 2.22, 95% CI 1.07-4.77; p = 0.03) were unfavorable factors for hearing preservation. CONCLUSIONS Stereotactic radiosurgery achieved good long-term results in this series. Tumor control was acceptable, and there were few serious complications in patients with small- to medium-sized VSs. Unfortunately, hearing preservation was not satisfactory. However, the longer the observation period, the more important it becomes to compare post-SRS hearing decreases with the natural decline in untreated cases.

Pretreatment growth rate as a predictor of tumor control following Gamma Knife radiosurgery for sporadic vestibular schwannoma.

OBJECTIVE Over the last 30 years, stereotactic radiosurgery (SRS) has become an established noninvasive treatment alternative for small- to medium-sized vestibular schwannoma (VS). This study aims to further define long-term SRS tumor control in patients with documented pretreatment tumor growth for whom conservative observation failed. METHODS A prospective clinical database was queried, and patients with sporadic VS who elected initial observation and subsequently underwent SRS after documented tumor growth between 2004 and 2014 were identified. Posttreatment tumor growth or shrinkage was determined by a ≥ 2-mm increase or decrease in maximum linear dimension, respectively. RESULTS Sixty-eight patients met study inclusion criteria. The median pre- and posttreatment observation periods were 16 and 43.5 months, respectively. The median dose to the tumor margin was 13 Gy (range 12-14 Gy), and the median maximum dose was 26 Gy (range 24-28 Gy). At the time of treatment, 59 tumors exhibited extracanalicular (EC) extension, and 9 were intracanalicular (IC). Of the 59 EC VSs, 50 (85%) remained stable or decreased in size following treatment, and 9 (15%) enlarged by > 2 mm. Among EC tumors, the median pretreatment tumor growth rate was 2.08 mm/year for tumors that decreased or were stable, compared with 3.26 mm/year for tumors that grew following SRS (p = 0.009). Patients who demonstrated a pretreatment growth rate of < 2.5 mm/year exhibited a 97% tumor control rate, compared with 69% for those demonstrating ≥ 2.5 mm/year of growth prior to SRS (p = 0.007). No other analyzed variables were found to predict tumor growth following SRS. CONCLUSIONS Overall, SRS administered using a marginal dose between 12-14 Gy is highly effective in treating VSs in which initial observation fails. Tumor control is achieved in 97% of VSs that exhibit slow (< 2.5 mm/year) pretreatment growth; however, SRS is less successful in treating tumors exhibiting rapid growth (≥ 2.5 mm/year).

Communicating Hydrocephalus Associated with Small- to Medium-Sized Vestibular Schwannomas: Clinical Significance of the Tumor Apparent Diffusion Coefficient Map

The etiology of hydrocephalus associated with the small- to medium-sized vestibular schwannomas is still controversial. We investigated tumor-specific factors related to the association of hydrocephalus with small- to medium-sized vestibular schwannomas. Among the 77 patients with vestibular schwannoma smaller than 30 mm, 9 patients demonstrated associated communicating hydrocephalus. Patient medical records, radiologic data, and histopathologic specimens were reviewed retrospectively. The age of the patients, and size, mean apparent diffusion coefficient (ADC) value, and histologic features of the tumors were compared with those of patients without hydrocephalus. The symptoms related to hydrocephalus improved in all patients after tumor removal. Both the mean size and ADC values exhibited a statistically significant difference between the tumors with and without hydrocephalus (P < 0.01). The size and ADC value of the tumor were significantly related to the association with hydrocephalus. Theincreased tumor ADC value was considered to be the result of degenerative change and suggested the involvement of protein sloughing in the etiology of the associated hydrocephalus.

Does where you live influence how your vestibular schwannoma is managed? Examining geographical differences in vestibular schwannoma treatment across the United States

The management of small- to medium-sized vestibular schwannoma (VS) remains controversial. Despite a lack of compelling evidence supporting one treatment modality over others, many providers and institutions remain highly biased toward one particular therapy-microsurgery, radiation, or primary observation. The objective of the current study was to estimate the impact of geography on disease presentation and initial treatment of VS in the United States. An analysis of the Surveillance, Epidemiology, and End Results (SEER) database identified 9761 patients with VS that were managed across the 16 SEER geographic registry areas. Univariate analyses demonstrated strong associations between geographic location and tumor size at diagnosis (P < 0.0001). When analyzing the 6115 subjects with tumors between 0 and 3cm in size, multivariable models identified strong associations between place of residence and treatment modality (P < 0.0001). These multivariable models demonstrated that in many cases the impact of place of residence on treatment selection was greater than other established variables such as tumor size and age. To our knowledge, this is the first study to evaluate geographic trends in VS patient demographics, tumor size and management in the United States. These data suggest that disease presentation and treatment modality are significantly influenced by regional referral patterns, provider or institutional treatment preferences, and regional availability of subspecialty expertise. Understanding geographic bias is important for patients, referring physicians, and treatment providers alike. Until there is clear evidence supporting one therapy over others, multidisciplinary consultation with a minimum of a neurotologist, neurosurgeon, and radiation oncologist or radiosurgeon should be offered in order to provide balanced counseling and accurate informed consent.

Pretreatment Growth Rate as a Predictor of Tumor Control Following Gamma Knife Radiosurgery for Sporadic Vestibular Schwannoma

OBJECTIVE Over the last 30 years, stereotactic radiosurgery (SRS) has become an established noninvasive treatment alternative for small- to medium-sized vestibular schwannoma (VS). This study aims to further define long-term SRS tumor control in patients with documented pretreatment tumor growth for whom conservative observation failed. METHODS A prospective clinical database was queried, and patients with sporadic VS who elected initial observation and subsequently underwent SRS after documented tumor growth between 2004 and 2014 were identified. Posttreatment tumor growth or shrinkage was determined by a ≥ 2-mm increase or decrease in maximum linear dimension, respectively. RESULTS Sixty-eight patients met study inclusion criteria. The median pre- and posttreatment observation periods were 16 and 43.5 months, respectively. The median dose to the tumor margin was 13 Gy (range 12-14 Gy), and the median maximum dose was 26 Gy (range 24-28 Gy). At the time of treatment, 59 tumors exhibited extracanalicular (EC) extension, and 9 were intracanalicular (IC). Of the 59 EC VSs, 50 (85%) remained stable or decreased in size following treatment, and 9 (15%) enlarged by > 2 mm. Among EC tumors, the median pretreatment tumor growth rate was 2.08 mm/year for tumors that decreased or were stable, compared with 3.26 mm/year for tumors that grew following SRS (p = 0.009). Patients who demonstrated a pretreatment growth rate of < 2.5 mm/year exhibited a 97% tumor control rate, compared with 69% for those demonstrating ≥ 2.5 mm/year of growth prior to SRS (p = 0.007). No other analyzed variables were found to predict tumor growth following SRS. CONCLUSIONS Overall, SRS administered using a marginal dose between 12-14 Gy is highly effective in treating VSs in which initial observation fails. Tumor control is achieved in 97% of VSs that exhibit slow (< 2.5 mm/year) pretreatment growth; however, SRS is less successful in treating tumors exhibiting rapid growth (≥ 2.5 mm/year).

Long-term Auditory Symptoms in Patients With Sporadic Vestibular Schwannoma: An International Cross-Sectional Study.

There are limited data on the long-term auditory symptoms in patients with sporadic small- and medium-sized vestibular schwannoma (VS). The initial treatment strategy for VS is controversial. To characterize auditory symptoms in a large cohort of patients with VS. Patients with ≤3 cm VS who underwent primary microsurgery, gamma knife surgery, or observation between 1998 and 2008 at 2 independent hospitals were identified. Clinical data were extracted from existing VS databases. At a mean time of 7.7 years after initial treatment, patients were surveyed via mail with the use of the Hearing Handicap Inventory for Adults (HHIA) and the Tinnitus Handicap Inventory. The response rate was 79%; a total of 539 respondents were analyzed. Overall, the hearing prognosis was poor, because more than 75% of all patients had nonserviceable hearing at the last clinical follow-up. Good baseline hearing proved to be a strong predictor for maintained serviceable hearing. Treatment modality was independently associated with both audiometric outcome and HHIA results. Active treatment with microsurgery or gamma knife surgery did not appear to be protective, because patients who were observed had the greatest probability of durable hearing. Patients in the surgical series had the greatest hearing loss. Tinnitus Handicap Inventory results were less predictable. The only predictors of tinnitus handicap were age and HHIA score. The overall prognosis for hearing in sporadic VS is poor regardless of treatment strategy. Treatment modality was an independent predictor of hearing status; observation was associated with the highest rate of hearing preservation. .

Functional Preservation After Planned Partial Resection Followed by Gamma Knife Radiosurgery for Large Vestibular Schwannomas

The treatment goal for vestibular schwannomas (VS) has been changed from total removal of the tumor to functional preservation with long-term tumor growth control. The small- to medium-sized VS can be treated by stereotactic radiosurgery, but large VS require surgical decompression for the relief of cerebellar dysfunction and increased intracranial pressure. We have been performing planned partial surgical resections followed by gamma knife radiosurgery (GKS) for large VS. Here, we evaluate a recent series of such cases from the standpoint of functional outcomes. From January 2000 to May 2013, we treated 40 patients with large unilateral VS (maximum tumor diameter at least 25 mm) with planned partial tumor removal followed by GKS for functional preservation. The median maximum diameter of the tumors was 32.5 mm (range 25-52 mm). All patients underwent surgery via the retrosigmoid approach, and tumors situated on the ventral and in the internal auditory canal intentionally were not removed, thus preserving cranial nerve functions. GKS was performed 1-12 months after surgical resection (median interval 3 months). The median tumor volume at GKS was 3.3 cm(3) (range 0.4-10.4 cm(3)) and the median prescribed dose was 12 Gy (range 10-12 Gy). The median follow-up period after GKS was 65 months (18-156 months). At the final follow-up, facial nerve preservation (House-Brackmann grade I-II) was achieved in 38 patients (95%; House-Brackmann grade I: 92.5%, II: 2.5%). Among the 14 patients with preoperative pure tone average (PTA) less than 50 dB, 6 of them (42.9%) maintained PTA less than 50 dB at the last follow-up. Two patients improved from severe hearing loss to PTA less than 50 dB (1 patient after surgery and 1 patient one and half years after GKS). Five- and 10-year tumor growth control occurred in 86% of patients. Four patients (10%) required salvage surgery; the predictive factor was tumor volume greater than 6 cm(3) at GKS (P= 0.01). Planned partial removal of large VS followed by GKS achieved a high rate of facial nerve and hearing preservation. To achieve long-term tumor growth control, the tumor volume at GKS after planned partial surgical resection should be smaller than 6 cm(3). Our results revealed that patients with hearing preservation postoperatively have a chance of maintaining hearing function, even though the possibility exists of deterioration by long-term follow-up after surgical intervention and GKS. Furthermore, some patients with severe hearing loss before treatment have the chance of hearing improvement, even those with large VS.

Repeat Gamma Knife surgery for vestibular schwannomas.

Background:Gamma Knife (GK) surgery is a recognized treatment option for the management of small to medium-sized vestibular schwannoma (VS) associated with high-tumor control and low morbidity. When a radiosurgical treatment fails to stop tumor growth, repeat GK surgery can be proposed in selected cases.Methods:A series of 27 GK retreatments was performed in 25 patients with VS; 2 patients underwent three procedures. The median time interval between GK treatments was 45 months. The median margin dose used for the first, second, and third GK treatments was 12 Gy, 12 Gy, and 14 Gy, respectively. Six patients (4 patients for the second irradiation and 2 patients for the third irradiation) with partial tumor regrowth were treated only on the growing part of the tumor using a median margin dose of 13 Gy. The median tumor volume was 0.9, 2.3, and 0.7 cc for the first, second, and third treatments, respectively. Stereotactic positron emission tomography (PET) guidance was used for dose planning in 6 cases.Results:Mean follow-up duration was 46 months (range 24–110). At the last follow-up, 85% of schwannomas were controlled. The tumor volume decreased, remained unchanged, or increased after retreatment in 15, 8, and 4 cases, respectively. Four patients had PET during follow-up, and all showed a significant metabolic decrease of the tumor. Hearing was not preserved after retreatment in any patients. New facial or trigeminal palsy did not occur after retreatment.Conclusions:Our results support the long-term efficacy and low morbidity of repeat GK treatment for selected patients with tumor growth after initial treatment.

What drives quality of life in patients with sporadic vestibular schwannoma?

To investigate the influence of posttreatment audiovestibular symptoms, facial neuropathy, and headache on long-term quality-of-life outcomes in patients with sporadic vestibular schwannoma (VS) utilizing the Short Form 36 (SF-36) Health Survey and the Penn Acoustic Neuroma Quality of Life (PANQOL) scale. Cross-sectional observation study. Patients with sporadic small- or medium-sized VS (< 3.0 cm) who were evaluated between 1998 and 2008 at two independent tertiary academic referral centers were surveyed. Multivariable associations with the PANQOL total score and the SF-36 physical and mental component scores evaluated using regression analysis. A total of 538 surveyed patients returned a completed questionnaire, providing a response rate of 79%. Two hundred forty-seven (46%) patients underwent stereotactic radiosurgery, 143 (27%) microsurgery, and 148 (28%) observation. Multivariable regression analysis revealed that ongoing dizziness was associated with the greatest reduction in PANQOL total score, followed by headache. After adjusting for all examined features, ongoing dizziness and ongoing headache were the only two variables that were associated with both the SF-36 physical and mental component scores. Patient sex and treatment modality did not significantly influence PANQOL or SF-36 scores. Ongoing dizziness and headache are the strongest predictors of long-term quality-of-life reduction in patients with sporadic VS, while the impact of hearing loss, facial nerve function, and tinnitus are less by comparison. This information may be valuable for patient counseling, refinement of VS quality-of-life assessment instruments, and determining high-yield targets for therapy in efforts to further improve patient outcomes.

Long-term follow-up studies of Gamma Knife surgery for patients with neurofibromatosis Type 2.

The aim of this study was to evaluate long-term clinical outcomes after Gamma Knife surgery (GKS) for patients with neurofibromatosis Type 2 (NF2) and the role of GKS in the management of NF2. From December 1994 through December 2008, a total of 46 patients (21 male, 25 female) with NF2 underwent GKS and follow-up evaluation for at least 5 years at the Gamma Knife Center of the Beijing Neurosurgical Institute. GKS was performed using the Leksell Gamma Knife Models B and C. The mean age of the patients was 30 years (range 13-59 years). A family history of NF2 was found for 9 (20%) patients. The NF2 phenotype was thought to be Wishart for 20 (44%) and Feiling-Gardner for 26 (56%) patients. Among these 46 patients, GKS was performed to treat 195 tumors (73 vestibular schwannomas and 122 other tumors including other schwannomas and meningiomas). For vestibular schwannomas, the mean volume was 5.1 cm(3) (median 3.6 cm(3), range 0.3-27.3 cm(3)), the mean margin dose was 12.9 Gy (range 10-14 Gy), and the mean maximum dose was 27.3 Gy (range 16.2-40 Gy). For other tumors, the mean volume was 1.7 cm(3) (range 0.3-5.5 cm(3)), the mean margin dose was 13.3 Gy (range 11-14 Gy), and the mean maximum dose was 26.0 Gy (range 18.0-30.4 Gy). The median duration of follow-up was 109 months (range 8-195 months). For the 73 vestibular schwannomas that underwent GKS, the latest follow-up MR images demonstrated regression of 30 (41%) tumors, stable size for 31 (43%) tumors, and enlargement of 12 (16%) tumors. The total rate of tumor control for bilateral vestibular schwannomas in patients with NF2 was 84%. Of the 122 other types of tumors that underwent GKS, 103 (85%) showed no tumor enlargement. The rate of serviceable hearing preservation after GKS was 31.9% (15/47). The actuarial rates for hearing preservation at 3 years, 5 years, 10 years, and 15 years were 98%, 93%, 44%, and 17%, respectively. Of the 46 patients, 22 (48%) became completely bilaterally deaf, 17 (37%) retained unilateral serviceable hearing, and 7 (15%) retained bilateral serviceable hearing. The mean history of the disease course was 12 years (range 5-38 years). GKS was confirmed to provide long-term local tumor control for small- to medium-sized vestibular schwannomas and other types of tumors, although vestibular schwannomas in patients with NF2 responded less well than did unilateral sporadic vestibular schwannomas. Phenotype is the most strongly predictive factor of final outcome after GKS for patients with NF2. The risk for loss of hearing is high, whereas the risk for other cranial nerve complications is low.

Long-term dizziness handicap in patients with vestibular schwannoma: a multicenter cross-sectional study.

(1) To characterize long-term dizziness following observation, microsurgery, and stereotactic radiosurgery (SRS) for small to medium-sized vestibular schwannoma (VS) using a validated self-assessment inventory; and (2) to identify clinical variables associated with long-term dizziness handicap. Cross-sectional observational study. Two independent tertiary academic referral centers: one located in the United States and one in Norway. All patients with sporadic VS of less than 3 cm who underwent primary microsurgery, SRS, or observation between 1998 and 2008 were identified. Subjects were surveyed via a postal questionnaire using the Dizziness Handicap Inventory (DHI) and a VS symptom questionnaire. The overall survey response rate was 79%. A total of 538 respondents (mean age, 64 years; 56% female) were analyzed, and the mean time interval between treatment and survey was 7.7 years. Pretreatment variables associated with greater dizziness handicap included female sex, older age, larger tumor size, preexisting diagnosis of headache or migraine, and symptoms of dizziness predating treatment. Significant posttreatment features strongly associated with poor long-term DHI scores included frequency and severity of ongoing headache. On multivariable analysis, treatment modality did not influence long-term dizziness handicap. At a mean of approximately 8 years following treatment, over half of patients with VS reported ongoing dizziness. The authors have identified several baseline features that may help predict the risk of lasting dizziness. Treatment modality does not appear to influence long-term DHI score. We found a strong association between posttreatment headache and poor dizziness handicap. Future study is needed to further define this relationship.

Vestibular Schwannomas Treatment in the 21st Century: Surgery or Radiosurgery?

Even nowadays the treatment of vestibular schwannomas (VS) may be challenging and lead to less than optimal outcome. Established treatment options are microsurgical removal and radiosurgery. The number of patients treated with radiosurgery worldwide increases. Although in the majority this treatment leads to tumor growth control, the overall number of treatment failures also increases. Management of patients after unsuccessful radiosurgery is especially challenging. On the other hand the number of small or medium-sized VS that are operated is diminishing, which hinders the learning process and gaining microsurgical experience. Ultimate goal of VS treatment is cure of the patient and preservation of all neurological functions, respectively of the quality of life. In this presentation the role of surgery and radiosurgery in achieving this goal will be discussed. The advantages and drawbacks of both treatment modes will be highlighted based on a critical review of the literature and own/institutional experience.

Spontaneous Size Regression of a Vestibular Schwannoma

Spontaneous Size Regression of a Vestibular Schwannoma Vestibular schwannomas are the most commonly occurring skull base tumors. Increasing availability of magnetic resonance imaging has allowed early recognition of these tumors and better characterization of their natural course. Recently, several series have presented data with regard to the slow growth of these tumors and challenged the need for tumor resection or radiation in cases involving small to medium-sized tumors. This is a case report of spontaneous regression of a medium-sized vestibular schwannoma occurring after initial slow tumor growth.