Gamma Knife surgery for patients with jugular foramen schwannomas: a multiinstitutional retrospective study in Japan

Surgical management of large lower cranial nerves schwannomas: long term results of a less aggressive resection strategy

In an effort to reduce the high morbidity and life-threatening complications after radical resection in large schwannoma surgery, alternative strategies of nontotal resections have emerged. To evaluate the long term clinical and oncological outcome after lower cranial nerves (LCN) schwannoma surgery operated on with a cranial nerve-sparing technique. Single center retrospective cohort study of 8 consecutive patients harboring LCN schwannomas operated on between March 2005 and October 2021. The mean LCN schwannoma diameter was 33 mm (range 26-51). Seven patients (87,5%) underwent a modified retrosigmoid approach. Three patients underwent gross total resection (37,5%), 3 had received neartotal resection (mean tumor residue 0,25 cc) and subtotal resection in 2 patients who presented with an extracranial extension of the tumor (mean tumor residue 2,44 cc). Both patients had received upfront additional GKRS. The three patients who presented with preoperative CN IX & X injuries recovered within 6 months after surgery. All of the five patients freed from any preoperative CNs IX & X symptoms experienced transient (80%) or definitive (one patient) disturbances after surgery. They all improved within 6 months but one who required long term gastrostomy feeding tube. This patient harbored a schwannoma originating from the glossopharyngeal nerve, which could not be anatomically preserved during surgery. Tumor control was achieved in 100% of cases with a mean follow-up of 91 months. LCN schwannomas could be surgically removed through a less aggressive non-radical resection strategy with acceptable functional results and excellent tumor control.

Lower Cranial Nerve Schwannomas: Cohort Study and Systematic Review

BACKGROUND AND OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Triggered episodic vestibular syndrome and transient loss of consciousness due to a retrostyloidal vagal schwannoma: a case report

Background

Various conditions may trigger episodic vertigo or dizziness, with positional changes being the most frequently identified condition. In this study, we describe a rare case of triggered episodic vestibular syndrome (EVS) accompanied by transient loss of consciousness (TLOC) linked to retrostyloidal vagal schwannoma.

Case description

A 27-year woman with known vestibular migraine presented with a 19-month history of nausea, dysphagia, and odynophagia triggered by swallowing food and followed by recurrent TLOC. These symptoms occurred independently of her body position, resulting in a weight loss of 10 kg within 1 year and in an inability to work. An extensive cardiologic diagnostic work-up undertaken before she presented to the neurologic department was normal. On the fiberoptic endoscopic evaluation of swallowing, she showed a decreased sensitivity, a slight bulging of the right lateral pharyngeal wall, and a pathological pharyngeal squeeze maneuver without any further functional deficits. Quantitative vestibular testing revealed an intact peripheral-vestibular function, and electroencephalography was read as normal. On the brain MRI, a 16 x 15 x 12 mm lesion in the right retrostyloidal space suspicious of a vagal schwannoma was detected. Radiosurgery was preferred over surgical resection, as resection of tumors in the retrostyloid space bears the risk of intraoperative complications and may result in significant morbidity. A single radiosurgical procedure (stereotactic CyberKnife radiosurgery, 1 x 13Gy) accompanied by oral steroids was performed. On follow-up, a cessation of (pre)syncopes was noted 6 months after treatment. Only residual infrequent episodes of mild nausea were triggered by swallowing solid food remained. Brain MRI after 6 months demonstrated no progression of the lesion. In contrast, migraine headaches associated with dizziness remained frequent.

Discussion

Distinguishing triggered and spontaneous EVS is important, and identifying specific triggers by structured history-taking is essential. Episodes being elicited by swallowing solid foods and accompanied by (near) TLOC should initiate a thorough search for vagal schwannoma, as symptoms are often disabling, and targeted treatment is available. In the case presented here, cessation of (pre)syncopes and significant reduction of nausea triggered by swallowing was noted with a 6-month delay, illustrating the advantages (no surgical complications) and disadvantages (delayed treatment response) of first-line radiotherapy in vagal schwannoma treatment.

Surgical Management of Craniovertebral Junction Schwannomas: A Systematic Review

Background: Craniovertebral junction (CVJ) schwannomas are rare, with surgery and stereotactic radiosurgery (SRS) being effective yet challenging options. We systematically reviewed the literature on CVJ schwannomas. Methods: PubMed, Scopus, Web-of-Science, and Cochrane were searched following the PRISMA statement to include studies reporting CVJ schwannomas. Clinical features, management, and outcomes were analyzed. Results: We collected 353 patients from 101 included articles. Presenting symptoms were mostly neck pain (30.3%) and headache (26.3%), with most cranial neuropathies involving the XII (31.2%) and X (24.4%) nerves. Most tumors originated from C2 (30.9%) and XII (29.4%) nerves, being extracranial (45.1%) and intradural-extradural (44.2%). Erosion of C1–C2 vertebrae (37.1%), the hypoglossal canal (28.3%), and/or jugular foramen (20.1%) were noted. All tumors were operated, preferably with the retrosigmoid approach (36.5%), with the far-lateral approach (29.7%) or with the posterior approach and cervical laminectomy (26.9%), far-lateral approaches (14.2%), or suboccipital craniotomy with concurrent cervical laminectomy (14.2%). Complete tumor resection was obtained most frequently (61.5%). Adjuvant post-surgery stereotactic radiosurgery was delivered in 5.9% patients. Median follow-up was 27 months (range, 12–252). Symptom improvement was noted in 88.1% of cases, and cranial neuropathies showed improvement in 10.2%. Post-surgical complications occurred in 83 patients (23.5%), mostly dysphagia (7.4%), new cranial neuropathies (6.2%), and cerebrospinal fluid leak (5.9%). A total of 16 patients (4.5%) had tumor recurrence and 7 died (2%), with median overall survival of 2.7 months (range, 0.1–252). Conclusions: Microsurgical resection is safe and effective for CVJ schwannomas. Data on SRS efficacy and indications are still lacking, and its role deserves further evaluation.

Clinical outcomes of benign brain tumors treated with single fraction LINAC-based stereotactic radiosurgery: Experience of a single institute

Objectives

Accelerator-based stereotactic radiosurgery (SRS) is a noninvasive and effective treatment modality widely used for benign brain tumors. This study aims to report 20-year treatment outcomes in our institute.

Materials and Methods

From May 2001 to December 2020, 127 patients treated with LINAC-based single-fraction SRS for their benign brain lesions were included. A neurosurgeon and two radiation oncologists retrospectively reviewed all data. Computed tomography (CT) simulation was performed after head-frame fixation under local anesthesia. All planning CT images were co-registered and fused with gadolinium-enhanced magnetic resonance imaging taken within 3 months for lesions targeting and critical organs delineation. The marginal dose was prescribed at 60%-90% isodose lines, respectively, to cover ≥95% planning target volume. Outcome evaluations included clinical tumor control rate (TCR), defined as the need for salvage therapy, and radiological response, defined as no enlargement of >2 cm in the maximal diameter. Overall survival (OS) and adverse reaction (defined according to CTCAE 5.0) were also analyzed.

Results

The present study included 76 female and 51 male patients for analysis. The median age was 59 years (range, 20-88 years). Their diagnoses were vestibular schwannoma (VS, n = 54), nonvestibular cranial nerve schwannoma (n = 6), meningioma (n = 50), and pituitary adenoma (n = 17). Totally 136 lesions were treated in a single fraction, predominantly skull base tumors, accounting for 69.1%. Median and mean follow-up duration was 49 and 61 months (range, 1-214 months), Overall TCR was 92.9%. The 5-year disease-specific TCR for VS, nonvestibular schwannoma, meningioma, and pituitary adenoma were 97.4%, 91.7%, 93.8%, and 83.3%. Salvage therapy was indicated for eight patients at 4-110 months after SRS. Among symptomatic patients, post-SRS symptom(s) was improved, stable, and worse in 68.2%, 24.3%, and 3.6%, respectively. Radiological response rate for 111 evaluable patients was 94.6% (shrinkage, 28.8%; stable, 65.8%). OS was 96.1% without treatment-related mortality. One patient with post-SRS cranial nerve injury (0.8%, involving the trigeminal nerve, grade 2 toxicities). No grade 3-4 acute or late toxicity was found.

Conclusion

Our results suggested that LINAC-based SRS effectively controls tumor growth and tumor-related neurological symptoms for patients with benign brain tumors. SRS is less aggressive, associated with low neurological morbidity and no mortality. Continuous follow-up is indicated to conclude longer outcomes.

Early-onset adverse events after stereotactic radiosurgery for jugular foramen schwannoma: a mid-term follow-up single-center review of 46 cases

Background

Recently, stereotacitc radiosurgery (SRS) has been in the spotlight as an alternative therapeutic option for jugular foramen schwannomas (JFS). While most reported studies focus on the long-term efficacy and safety issues of SRS, none describe the early-onset adverse events (eAEs). We aimed to investigate the incidence, clinical characteristics, and mid-term outcomes of eAEs occurring within six months after SRS for JFS.

Methods

In this retrospective review, patients who underwent at least six months of follow-up were included among all patients with JFS who have performed SRS at our institution between July 2008 and November 2019. And eAEs were defined as a newly developed neurological deficit or aggravation of pre-existing symptoms during the first six months after SRS.

Results

Forty-six patients were included in the analysis. The median follow-up period was 50 months (range 9–136). The overall tumor control rate was 91.3%, and the actuarial 3-, 5-, and 10-year progression-free survival rates were 97.8%, 93.8%, and 76.9%, respectively. Of the 46 patients, 16 had eAEs, and the median time to onset of eAEs was one month (range 1–6 months), and the predominant symptoms were lower cranial nerve dysfunctions. Thirteen of 16 patients showed improved eAE symptoms during the follow-up period, and the median resolution time was six months (range 1–52). In 11 (68.8%) of 16 patients with eAEs, transient expansions were observed with a mean of 3.6 months after the onset of eAEs, and the mean difference between the initial tumor volume and the transient expansion volume was more prominent in the patients with eAEs (3.2 cm³ vs. 1.0 cm³; p = 0.057). In univariate analysis, dumbbell-shaped tumors (OR 10.56; p = 0.004) and initial tumor volume (OR 1.32; p = 0.033) were significantly associated with the occurrence of eAEs.

Conclusions

Although acute adverse events after SRS for JFS are not rare, these acute effects were not permanent and mostly improved with the steroid treatment. Dumbell-shaped and large-volume tumors are significant predictive factors for the occurrence of eAEs. And the transient expansion also seems to be closely related to eAEs. Therefore, clinicians need to be more cautious when treating these patients and closely monitor the occurrence of eAEs.

Management of non-vestibular schwannomas in adult patients: a systematic review and consensus statement on behalf of the EANS skull base section Part III: Lower cranial nerve schwannomas, jugular foramen (CN IX, X, XI) and hypoglossal schwannoma (XII)

BACKGROUND

Non-vestibular schwannomas are relatively rare, with trigeminal and jugular foramen schwannomas being the most common. This is a heterogenous group which requires detailed investigation and careful consideration to management strategy. The optimal management for these tumours remains unclear, and there are several controversies. The aim of this paper is to provide insight into the main principles defining management and surgical strategy, in order to formulate a series of recommendations.

METHODS

A task force was created by the EANS skull base section committee along with its members and other renowned experts in the field to generate recommendations for the surgical management of these tumours on a European perspective. To achieve this, the task force performed an extensive systematic review in this field and had discussions within the group. This article is the third of a three-part series describing non-vestibular schwannomas (IX, X, XI, XII).

RESULTS

A summary of literature evidence was proposed after discussion within the EANS skull base section. The constituted task force dealt with the practice patterns that exist with respect to preoperative radiological investigations, ophthalmological assessments, optimal surgical and radiotherapy strategies and follow-up management.

CONCLUSION

This article represents the consensually derived opinion of the task force with respect to the treatment of non-vestibular schwannomas. For each of these tumours, the management paradigm is shifting towards the compromise between function preservation and progression free survival.

Less common extracerebral tumors

This chapter examines the results of GKNS on a variety of extraparenchymal skull base tumors some benign and some malignant. For the benign tumors there is good evidence on the effectiveness of the method for pretty much all diagnoses. For malignant extraparenchymal tumors the results are more limited and GKNS only has a supportive role in these lesions.

Surgical treatment of dumbbell-shaped jugular foramen schwannomas via two-piece lateral suboccipital approach: Report of 26 patients

BACKGROUND

Dumbbell-shaped jugular foramen schwannomas (JFS) are rare but challenging for the treatment. Surgical resection is believed to be the optimal therapy; however, postoperative dysfunction of the lower cranial nerves (CNs), tumor residual, cerebrospinal fluid (CSF) leakage, and subcutaneous hydrops are common. The current study's objectives were to describe the optimal surgical strategies for the total removal of dumbbell-shaped JFS, the functional preservation of lower CNs, and the prevention of postoperative CSF leakage.

METHODS

26 consecutive patients with dumbbell-shaped JFS were surgically treated between January 2014 and June 2019. All patients were operated on via two-piece lateral suboccipital approach, vascularized muscle flap was used for the repair of the dural defect after an operation. The clinical information and radiological data of these patients were retrospectively reviewed, and the optimal surgical strategies were further evaluated and discussed.

RESULTS

The tumor was completely removed in all 26 patients, one patient developed new CN Ⅶ paralysis, and 2 developed new CN IX and Ⅹ paralysis after an operation, all patients were significantly relieved during follow up. None of them developed subcutaneous hydrops and postoperative CSF leakage. No tumor recurrence was observed during a mean follow up of 38.8 (16-69) months.

CONCLUSIONS

Dumbbell-shaped JFS could be safely and completely removed via the two-piece lateral suboccipital approach. Postoperative CSF leakage could be effectively prevented by careful repair of the dural defect in the jugular foramen (JF) and filling the mastoid cavity with a vascularized muscular flap.

Intratumoral hemorrhage in jugular foramen schwannoma after stereotactic radiosurgery: A case report

Background:

Clinically significant intratumoral hemorrhage is a rare complication of stereotactic radiosurgery (SRS) for benign tumors.

Case Description:

Here, we present the case of a 64-year-old man who underwent SRS for a relatively large dumbbell-shaped left jugular foramen schwannoma (JFS) and thereafter developed intratumoral hemorrhage. On post-SRS day 3, he developed lower cranial nerve palsies with radiographically evident tumor expansion. His neurological conditions had gradually improved thereafter; however, he suddenly developed headache, dizziness, and mild hearing deterioration at 7 months due to intratumoral hemorrhage. We managed the patient conservatively, and eventually, his symptoms improved except for slight ataxia and hearing deterioration. Follow-up images at 4 years from SRS demonstrated significant tumor shrinkage. This is the first report describing intratumoral hemorrhage after SRS for JFS.

Conclusion:

Transient expansion of the tumor and subsequent venous stasis around the tumor may have played a role in the hemorrhage. Intratumoral hemorrhage should be considered as a rare, but potential complication of SRS for JFSs.

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

Simple Summary

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

Abstract

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

Trends in the Management of Non-Vestibular Skull Base and Intracranial Schwannomas

The aim of this review is to analyze the latest trends in the management of non-vestibular skull base and intracranial schwannomas in order to optimize tumor control and quality of life. Non-vestibular cranial nerve schwannomas are rare lesions, representing 5–10% of cranial nerve schwannomas. Management decisions should be individualized depending on tumor size, location and associated functional deficits. Generally, large sized schwannomas exerting significant mass effect with increased intracranial pressure are treated surgically. In some cases, even after optimal skull base resection, it is not possible to achieve a gross total resection because tumor location and extent and/or to reduce morbidity. Thus, subtotal resection followed by stereotactic radiosurgery or fractioned radiotherapy offers an alternative approach. In certain cases, stereotactic radiosurgery or radiotherapy alone achieves good tumor control rates and less morbidity to gross total resection. Finally, given the slow growth rate of most of these tumors, observation with periodic radiographic follow-up approach is also a reasonable alternative for small tumors with few, if any, symptoms.

Endoscopic transnasal resection of the CP angle schwannoma

Cerebellopontine (CP) angle tumors are often resected via retrosigmoid craniotomy; however, sometimes cranial nerves (CNs) make their resection more complex. In such cases, the endoscopic transnasal approach can avoid such manipulations as delivering surgical instruments over CNs or peeling off CNs from the tumor, minimizing the risk of postoperative deficits. A 35-year-old man presented with a 37-mm cystic tumor in the right CP angle, and preoperative 3D fusion images revealed that multiple CNs (VII, VIII, and lower CNs) were running on the tumor posteriorly. The endoscopic transnasal approach enabled safe subtotal resection without causing neurological deficits, and the patient underwent stereotactic radiosurgery for the residual schwannoma.

The video can be found here: https://youtu.be/xKLwdDsLpWA.

Optimal surgical approaches and treatment outcomes in patients with jugular foramen schwannomas: a single institution series of 31 cases and a literature review

Complete resection of jugular foramen schwannomas (JFSs) with minimal cranial nerve complications remains difficult even for skilled neurosurgeons. Between November 2011 and November 2017, 31 consecutive patients diagnosed with JFSs underwent a single-stage operation performed by the same neurosurgeon. We retrospectively analyzed clinical characteristics, surgical approaches, treatment outcomes, and follow-up data for these patients. JFSs were classified according to the Samii classification system. A retrosigmoid approach was used to resect type A tumors, while a suboccipital transjugular process (STJP) approach was used to resect type B tumors. Notably, the present study is the first to report the use of a paracondylar-lateral cervical (PCLC) approach for the treatment of type C and D tumors. Type A-D tumors were observed in seven, four, four, and 16 patients, respectively. Gross-total resection was achieved in 29 patients (93.5%). There were no cases of intracranial hematoma, re-operation, tracheotomy, or death. Adjunctive gamma knife treatment was used to manage residual tumors in two patients. Neurological deficits relieved in half of patients at the last follow-up. By reviewing the studies published on PubMed, the approaches gradually be more conservative, rather than widely expose the skull base. Nonetheless, endoscope and stereotactic radiosurgery plays an important role in the management of JFSs. Both tumor removal and neurological function retention can be obtained by choosing individual treatment.

Stereotactic radiosurgery for jugular foramen schwannomas: an international multicenter study

OBJECTIVE

For some jugular foramen schwannomas (JFSs), complete resection is possible but may be associated with significant morbidity. Stereotactic radiosurgery (SRS) is a minimally invasive alternative or adjunct to microsurgery for JFSs. The authors reviewed clinical and imaging outcomes of SRS for patients with these tumors.

METHODS

Nine participating centers of the International Gamma Knife Research Foundation identified 92 patients who underwent SRS between 1990 and 2013. Forty-one patients had prior subtotal microsurgical resection. The median interval between previous surgery and SRS was 15 months (range 0.5–144 months). Eighty-four patients had preexisting cranial nerve (CN) symptoms and signs. The median tumor volume was 4.1 cm3 (range 0.8–22.6 cm3), and the median margin dose was 12.5 Gy (range 10–18 Gy). Patients with neurofibromatosis were excluded from this study.

RESULTS

The median follow-up was 51 months (range 6–266 months). Tumors regressed in 47 patients, remained stable in 33, and progressed in 12. The progression-free survival (PFS) was 93% at 3 years, 87% at 5 years, and 82% at 10 years. In the entire series, only a dumbbell shape (extension extracranially via the jugular foramen) was significantly associated with worse PFS. In the group of patients without prior microsurgery (n = 51), factors associated with better PFS included tumor volume < 6 cm3 (p = 0.037) and non–dumbbell-shaped tumors (p = 0.015). Preexisting cranial neuropathies improved in 27 patients, remained stable in 51, and worsened in 14. The CN function improved after SRS in 12% of patients at 1 year, 24% at 2 years, 27% at 3 years, and 32% at 5 years. Symptomatic adverse radiation effects occurred in 7 patients at a median of 7 months after SRS (range 5–38 months). Six patients underwent repeat SRS at a median of 64 months (range 44–134 months). Four patients underwent resection at a median of 14 months after SRS (range 8–30 months).

CONCLUSIONS

Stereotactic radiosurgery proved to be a safe and effective primary or adjuvant management approach for JFSs. Long-term tumor control rates and stability or improvement in CN function were confirmed.

Maximum diameter versus volumetric assessment for the response evaluation of vestibular schwannomas receiving stereotactic radiotherapy

Purpose

To explore the feasibility of maximum diameter as a response assessment method for vestibular schwannomas (VS) after stereotactic radiosurgery or fractionated stereotactic radiotherapy (RT), we analyzed the concordance of RT responses between maximum diameters and volumetric measurements.

Materials and Methods

Forty-two patients receiving curative stereotactic radiosurgery or fractionated stereotactic RT for VS were analyzed retrospectively. Twelve patients were excluded: 4 did not receive follow-up magnetic resonance imaging (MRI) scans and 8 had initial MRI scans with a slice thickness >3 mm. The maximum diameter, tumor volume (TV), and enhanced tumor volume (ETV) were measured in each MRI study. The percent change after RT was evaluated according to the measurement methods and their concordances were calculated with the Pearson correlation. The response classifications were determined by the assessment modalities, and their agreement was analyzed with Cohen kappa statistics.

Results

Median follow-up was 31.0 months (range, 3.5 to 86.5 months), and 90 follow-up MRI studies were analyzed. The percent change of maximum diameter correlated strongly with TV and ETV (r(p) = 0.85, 0.63, p = 0.000, respectively). Concordance of responses between the Response Evaluation Criteria in Solid Tumors (RECIST) using the maximum diameters and either TV or ETV were moderate (kappa = 0.58; 95% confidence interval, 0.32-0.85) or fair (kappa = 0.32; 95% confidence interval, 0.05-0.59), respectively.

Conclusion

The percent changes in maximum diameter and the responses in RECIST were significantly concordant with those in the volumetric measurements. Therefore, the maximum diameters can be used for the response evaluation of VS following stereotactic RT.

Toxicity of Gamma Knife Radiosurgery May Be Greater in Patients with Lower Cranial Nerve Schwannomas

Objective  Gamma Knife stereotactic radiosurgery (GK-SRS) is a preferred treatment option for tumors of the jugular foramen. We hypothesized that GK-SRS toxicity is higher for lower cranial nerve schwannomas than for glomus jugulare tumors despite anatomically similar locations. Methods  We performed a retrospective review of all patients who received GK-SRS for glomus jugulare tumors and lower cranial nerve schwannomas at our institution between 2006 and 2014. Because of small sample sizes, Fisher's exact tests and logistic regression techniques were employed using SPSS. Result  We identified 20 glomus jugulare tumors and 6 lower cranial nerve schwannoma patients with a median follow-up of 17 months. Median marginal dose was 16 Gy (range 13-18 Gy) and 12.5 Gy (range 12-14 Gy), respectively. All except one patient had tumor control at last follow-up visit. No worsening of pre-existing neurological deficits was observed. There were seven patients who developed any new neurological deficit after GK-SRS, four from the glomus group, and three from the schwannoma group (20 and 50% of each group, respectively). Only two of seven patients had permanent new neurological deficits. Both of them were in the schwannoma group. Univariate analysis showed that only a diagnosis of schwannoma had a greater risk of permanent new cranial nerve complication after GK-SRS compared with diagnosis of glomus jugulare ( p  = 0.046). Conclusion  Although the marginal dose for glomus jugulare is greater, our study suggests that the risk of a new permanent neurological deficit after GK-SRS was higher in the schwannoma group compared with the glomus group.

Stereotactic radiosurgery for non-vestibular cranial nerve schwanommas

Non-vestibular cranial nerve schwannomas (NVCNS) are rare lesions, representing <10 % of cranial nerve schwannomas. The optimal treatment for NVCNS is often derived from vestibular schwannomas experience. Surgical resection has been referred to as the first line treatment for those benign tumors, but significant complication rates are reported. Stereotactic radiosurgery (SRS) has arisen as a mainstay of treatment for many benign tumors, including schwanommas. We retrospectively reviewed the outcomes of NVCNS treated by SRS to characterize tumor control, symptom relief, toxicity, and the role of hypo-fractionation of SRS dose. Eighty-eight (88) patients, with ninety-five (95) NVCNS were treated with either single or multi-session SRS from 2001 to 2014. Local control was achieved in 94 % of patients treated (median follow-up of 33 months, range 1-155). Complications were seen in 7.4 % of cases treated with SRS. At 1-year, 57 % of patients had improvement or resolution of their symptoms, while 35 % were stable and 8 % had worsening or increased symptoms. While 42 % received only one session, results on local control were similar for one or multiple sessions (p = 0.424). SRS for NVCNS is a treatment modality that provides excellent local control with minimal complication risk compared to traditional neurosurgical techniques. Tumor control obtained with a multi-session treatment was not significantly different from single session treatment. Safety profile was also comparable for uni or multi-session treatments. We concluded that, as seen in VS treated with CK SRS, radiosurgery treatment can be safely delivered in cases of NVCNS.