The Relationship Between Jugular Foramen Schwannoma and Surrounding Membrane Structures and Its Surgical Application

BACKGROUND AND OBJECTIVES

Surgical resection of jugular foramen (JF) schwannomas with minimal neurological complications is challenging because of their difficult-to-access location and complex relationships with surrounding neurovascular structures, even for experienced neurosurgeons. In this article, we elucidate the membranous anatomy of JF schwannomas, with the aim of reducing iatrogenic injury to the lower cranial nerves (LCNs) during surgery.

METHODS

The clinical data of 31 consecutive patients with JF schwannomas were reviewed. The relationship between the tumor and the surrounding membranous structures was observed during dissection. Samples were analyzed using Masson's trichrome and immunofluorescence staining to study the membranous characteristics. Histological-radiographic correlations were also summarized.

RESULTS

In this series, we found that all 3 type B, 2 type C, and 8 type D tumors (according to the Kaye-Pellet grading system) were entirely extradural in location, whereas the 18 type A tumors could be subdural (9 cases) or extradural (9 cases), which frequently could not be predicted preoperatively based on whether the tumor had intraforaminal extension. The dural capsule, when present, could be used as an insulating layer to protect LCNs. With this subcapsular dissection technique, postoperative LCN dysfunction occurred in 10 patients (32.3%), which was usually temporary and mild.

CONCLUSION

The different relationships between the tumor and membranous structures of the JF is related to the distinct point of tumor origin and the complex anatomy of the meningeal dura within the JF. Subcapsular dissection technique is recommended for better preservation of LCNs when the dural capsule is identified.

Pure endoscopic presigmoid infralabyrinthine approach for jugular foramen tumors: Operative technique and early results

BACKGROUND

Jugular foramen (JF) tumors are uncommon, often requiring surgical resection due to their complex anatomical location and varied growth patterns, particularly when intraosseous.

OBJECTIVE

We propose the pure endoscopic presigmoid infralabyrinthine approach (EPSIL) as a minimally invasive technique for lateral JF access during tumor resection, circumventing the need for extensive exposure of vital structures and jugular vein sacrifice.

METHODS

A retrospective analysis was conducted on six patients who underwent EPSIL for JF tumor resection since 2020. The focus was on operative techniques, extent of tumor removal, neurological outcomes, and approach-related morbidity.

RESULTS

The cohort included six patients (three male, three female) with an average age of 46.9 years and a follow-up of 21.6 months. Tumor types were four schwannomas, one paraganglioma, and one chondrosarcoma (WHO grade 2), with average dimensions of 41.2 × 18.8 × 34.5 mm. All were successfully removed via EPSIL, aided by neuro-navigation and monitoring. Four achieved gross-total resections, two subtotal (>90 %), with the latter treated with Gamma Knife for remnants. No tumor recurrence or growth was noted. Preoperative symptoms improved postoperatively, with temporary hoarseness and slight hearing impairment resolving within 8 weeks. One patient had a cerebrospinal fluid leak, managed with a lumbar drain, without long-term deficits.

CONCLUSION

The EPSIL approach is a highly effective method for the removal of JF tumors, particularly those with intraosseous growth. It stands out as a minimally invasive procedure that harmoniously integrates radical tumor resection with the preservation of cranial nerves.

Stereotactic Radiosurgery and Surgical Resection for Jugular Foramen Schwannomas: A Retrospective Comparative Study of Outcomes

BACKGROUND AND OBJECTIVES

Jugular foramen schwannomas (JFS) are rare benign tumors arising from lower cranial nerves. In this study, we aim to compare the outcomes of surgical resection (SR) and stereotactic radiosurgery (SRS) in the treatment of JFS.

METHODS

We conducted a retrospective analysis of 31 patients with JFS who underwent SRS (13 patients [41.9%]) or surgical resection (18 patients [58.1%]) as their primary management modality over a two-decade period. Outcomes included progression-free survival, post-treatment adverse events based on Common Terminology Criteria for Adverse Events, symptom improvement, overall survival, and the necessity for secondary interventions. Local tumor control was also evaluated in all patients who received SRS.

RESULTS

Significant differences were observed in baseline characteristics between the SRS and SR groups, including median age (58 vs 48 years, P = .001), largest tumor diameter (32.0 vs 47.5 mm, P = .02), and total tumor volume (6.50 vs 20.5 mm3, P = .01). There were no significant differences in sex or lesion morphology (dumbbell vs nondumbbell shaped). After adjusting for baseline characteristics, no significant differences were noted in progression-free survival (90.9 vs 86.2%), overall survival (92.3 vs 100%), symptom improvement (61.5 vs 55.5%), or median Common Terminology Criteria for Adverse Events grade (1 in both groups) between the SRS and SR groups, respectively. SRS patients had significantly lower odds of requiring secondary treatment procedures after their primary intervention as compared with those who underwent SR (odds ratio = 0.02, 95% CI: 0.001-0.88, P-value = .04). Local tumor control in all SRS patients (19 patients) was 93.7% and 79.1% at six-month and five-year time points, respectively.

CONCLUSION

SRS and SR demonstrate comparable effectiveness in treating JFS. However, SRS may be a more favorable option because of a reduced need for secondary interventions. Future controlled prospective studies are needed to draw more definitive conclusions.

Gamma-knife radiosurgery for jugular foramen schwannomas. A systematic review and meta-analysis

Introduction

Jugular Foramen Schwannomas (JFS) have been traditionally treated with surgical resection with an associated significant post-operative morbidity. Stereotactic radiosurgery has been investigated as potentially minimally invasive alternative to microsurgery. The aim of this study was to provide a systematic review and meta-analysis of the available literature regarding the outcomes of cases of JFS treated with radiosurgery.

Methods

A literature review until 28th of March 2023 was performed. All studies looking at the outcomes of radiosurgery for the treatment of JFS were included. Studies including non-vestibular schwannomas without clear distinction of the tumour type were excluded. Risk of bias was assessed using the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) scale.

Results

Eight (8) studies with a total of 375 patients met the inclusion and exclusion criteria and were included in the analysis. Pooled overall tumour control rate was 93.2 % (95 % CI 89.8-96.6) after a weighted mean follow-up of 54.07 months (95 % CI 46.8-61.3). Patient free survival was reported only in 4 studies and ranged from 87 % to 97 % and 76.9-93.8 % in 5 and 10 years respectively. The radiation induced cranial nerve deficits rates after GKRS were 3.6 % (95%CI 1.7, 5.5 %).

Conclusion

According to our findings, radiosurgery for JFS has favourable clinical outcomes with a high rate of long-term tumour control and low complication rates.

Surgical resection and reconstruction techniques for jugular foramen schwannoma

INTRODUCTION

Jugular foramen schwannomas present formidable challenges due to their deep-seated location and complex anatomical constraints, leading to significant difficulties in tumor excision, postoperative complications further hinder surgical interventions in this area. We aim to explore and summarize surgical and reconstruction techniques for jugular foramen schwannomas to enhance patient outcomes.

MATERIALS AND METHODS

In a retrospective analysis, we reviewed the surgical approaches and reconstruction techniques utilized in 31 patients undergoing surgical resection for jugular foramen schwannomas from January 2018 to the present. Our goal was to summarize the materials and methods used for skull base reconstruction in this region and propose a clinically applicable procedural framework for surgical intervention.

RESULTS

Results revealed that 28 patients underwent treatment via the far lateral paracondylar approach, while 3 patients opted for the suboccipital retrosigmoid approach. Among them, 15 patients underwent surgical cavity tamponade. Additionally, we summarized three methods of dural reconstruction in the surgical area. Postoperative temporary complications showed varying degrees of improvement during follow-up, leading to an overall favorable prognosis.

CONCLUSION

Our study presents clinical insights into the surgical resection and skull base reconstruction of jugular foramen schwannomas. We discuss the selection of surgical approaches, intraoperative landmarks, and reconstruction techniques aimed at improving patient outcomes effectively.

Outcomes after Surgical Resection of Jugular Foramen Schwannomas: Systematic Review and Meta-Analysis

Objectives  We sought to perform a systematic review and meta-analysis of outcomes after surgical resection of jugular foramen schwannomas (JFSs). Design  A systematic review of the literature was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Setting  PubMed, Scopus, and Embase databases were searched. Participants  Case series of at least five patients undergoing surgical resection of JFSs were included. Main Outcome Measures  Primary outcomes included gross total resection (GTR) and near total resection (NTR) rates, as well as a composite of the two (GTR + NTR). Additional outcomes included new or worsening cranial nerve (CN) palsies and cerebrospinal fluid (CSF) leak. Random effects models were used to generate pooled outcomes. Results  A total of 25 studies comprising 567 patients were included in the study. The proportions of each tumor grade were the following: grade A (33.1%), grade B (16.1%), grade C (9.2%), and grade D (41.6%). The pooled rate of GTR was 81% (95% confidence interval [CI]: 70-88; I 2  = 78.9%) and the composite GTR + NTR rate was 88% (95% CI: 81-93; I 2  = 66.4%). Rates of new or worsening CN palsies were the following: 12% hearing loss (95% CI: 7-20; I 2  = 69.4%), 27% dysphagia (95% CI: 20-36; I 2  = 66%), 20% hoarseness (95% CI: 14-28; I 2  = 62.6%), and 19% facial palsy (95% CI: 13-28; I 2  = 64.6%). The pooled rate of CSF leak was 9% (95% CI: 6-15; I 2  = 43.9%). Conclusion  The literature suggests high GTR rates of JFSs can be achieved. However, new CN deficits are not uncommon.

Surgical results, technical notes and complications of jugular foramen lesions via retroauricular infratemporal fossa approach

OBJECTIVE

The objective of this study was to evaluate the clinical effect and safety of the postauricular infratemporal fossa approach (ITFA) in resecting jugular foramen lesions.

METHODS

All 25 patients undergoing microsurgery via postauricular ITFA from March 2015 to May 2023 in the Department of Neurosurgery, Tangdu Hospital, Air Force Military Medical University were included. The clinical and radiological data were retrospectively analyzed. Regular follow-up was carried out.

RESULTS

The mean age of all patients was 50.5±8.9 years, and 14 of them were female and 11 were male. Among the cases, lower cranial nerve schwannoma accounted for 60 % (15/25) of all tumors, jugular foramen paraganglioma accounted for 20 % (5/25), and the remaining 20 % included meningioma, chondrosarcoma, plasmacytoma, and salivary gland tumors. Total tumor resection was performed in 18 cases, subtotal tumor resection in 7 cases and partial resection in 1 case. Seven patients underwent gamma knife radiotherapy after surgery. Transient lower cranial nerve dysfunction occurred in 8 patients, and permanent lower cranial nerve dysfunction occurred in 2 patients after surgery. One patient developed facial paralysis, and one patient presented hearing loss.

CONCLUSIONS

The postauricular ITFA achieved a relatively high total tumor resection rate and a lower incidence of neurological functional disorders. It is an alternative and suitable surgical approach for resecting jugular foramen lesions. Maximizing the preservation of neurological function is preferred, especially when radical resection cannot be achieved. Stereotactic radiotherapy could be used for residual tumors.

Automated algorithm aided capacity and confidence boost in surgical decision-making training for inferior clivus

Objective

To assess the impact of automated algorithms on the trainees' decision-making capacity and confidence for individualized surgical planning.

Methods

At Chinese PLA General Hospital, trainees were enrolled to undergo decision-making capacity and confidence training through three alternative visual tasks of the inferior clivus model formed from an automated algorithm and given consecutively in three exemplars. The rationale of automated decision-making was used to instruct each trainee.

Results

Following automated decision-making calculation in 50 skull base models, we screened out three optimal plans, infra-tubercle approach (ITA), trans-tubercle approach (TTA), and supra-tubercle approach (STA) for 41 (82.00%), 8 (16.00%), and 1 (2.00%) subject, respectively. From September 1, 2023, through November 17, 2023, 62 trainees (median age [range]: 27 [26-28]; 28 [45.16%] female; 25 [40.32%] neurosurgeons) made a decision among the three plans for the three typical models (ITA, TTA, and STA exemplars). The confidence ratings had fine test-retest reliability (Spearman's rho: 0.979; 95% CI: 0.970 to 0.988) and criterion validity with time spent (Spearman's rho: -0.954; 95%CI: -0.963 to -0.945). Following instruction of automated decision-making, time spent (initial test: 24.02 vs. 7.13 in ITA; 30.24 vs. 7.06 in TTA; 34.21 vs. 12.82 in STA) and total hits (initial test: 30 vs. 16 in ITA; 37 vs. 17 in TTA; 42 vs. 28 in STA) reduced significantly; confidence ratings (initial test: 2 vs. 4 in ITA; 2 vs. 4 in TTA; 1 vs. 3 in STA) increased correspondingly. Statistically significant differences (P < 0.05) were observed for the above comparisons.

Conclusions

The education tool generated by automated decision-making considers surgical freedom and injury risk for the individualized risk-benefit assessment, which may provide explicit information to increase trainees' decision-making capacity and confidence.

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.

Trigeminal Schwannoma Surgery: Challenges in Preserving Facial Sensation

Treatments of schwannoma have dramatically improved in the previous few decades, but preservation of the functions of the originating nerve, such as facial sensation in trigeminal schwannomas, still remains challenging. As the preservation of facial sensation in trigeminal schwannomas has not been analyzed in detail, we here review our surgical experience of more than 50 trigeminal schwannoma patients, particularly focusing on their facial sensation. Since the facial sensation in each trigeminal division showed a different perioperative course even in a single patient, we investigated patient-based outcomes (average of the three divisions in each patient) and division-based outcomes separately. In the evaluation of patient-based outcomes, facial sensation remained postoperatively in 96% of all the patients, and improved in 26% and worsened in 42% of patients with preoperative hypesthesia. Posterior fossa tumors tended to most rarely disrupt facial sensation preoperatively, but were the most difficult to preserve facial sensation postoperatively. Facial pain was relieved in all six patients with preoperative neuralgia. In the division-based evaluation, facial sensation remained postoperatively in 83% of all the trigeminal divisions, and improved in 41% and worsened in 24% of the divisions with preoperative hypesthesia. The V3 region was most favorable before and after surgery, with the most frequent improvement and the least frequent functional loss. To clarify current treatment outcomes of the facial sensation and to achieve more effective preservation, standardized assessment methods of perioperative facial sensation may be required. We also introduce detailed MRI investigation methods for schwannoma, including contrast-enhanced heavily T2-weighted (CISS) imaging, arterial spin labeling (ASL), and susceptibility-weighted imaging (SWI), preoperative embolization for rare vascular-rich tumors, and modified techniques of the transpetrosal approach.

Morphometric comparison of Fisch type A and endoscopic endonasal far-medial supracondylar approaches to the jugular foramen

OBJECTIVE

The jugular foramen (JF) is one of the most complex and challenging skull base regions to approach surgically. The extreme medial approach to access the JF provides the approach angle from an anterior direction and does not require dissection and sacrifice of the jugular bulb (JB) to reach the pars nervosa. The authors compared the Fisch type A approach to the extreme medial approach to access the JF and evaluated the usefulness of the extreme medial approach.

METHODS

This study was performed at the Anatomical Laboratory for Visuospatial Innovations in Otolaryngology and Neurosurgery of The Ohio State University. For the comparison of surgical maneuverability and visualization, two angles were measured: 1) the angle of attack (AoA), defined as the widest angle of movement achieved with a straight dissector; and 2) the angle of endoscopic exposure (AoEE), defined as the widest angle of movement in the nasal cavity. The differences in eustachian tube (ET) management, approach angle, surgical maneuverability, and surgical application of the Fisch type A approach to the extreme medial approach were compared.

RESULTS

There was no difference between ET mobilization and transection regarding cranial-caudal (CC) or medial-lateral (ML) AoA (p = 0.646). The CC-AoA of the Fisch type A approach was significantly wider than the CC-AoA of the extreme medial approach (p = 0.001), and the CC-AoEE was significantly wider than the CC-AoA of the extreme medial approach (p < 0.001). There was no significant difference between the CC-AoA of the Fisch type A approach and the CC-AoEE. The ML-AoA of the Fisch type A approach was significantly wider than the ML-AoA of the extreme medial approach (p = 0.033), and the ML-AoEE was significantly wider than ML-AoA in the extreme medial approach (p < 0.001). The ML-AoEE was significantly wider than the ML-AoA in the Fisch type A approach (p = 0.033).

CONCLUSIONS

The surgical maneuverability of the extreme medial approach was not inferior to that of the Fisch type A approach. The extreme medial approach can provide excellent surgical field visualization, while preserving the JB. Select cases of chordomas, chondrosarcomas, and JF schwannomas should be considered for an extreme medial approach. These two approaches are complementary, and a case-by-case detailed analysis should be conducted to decide the best approach.

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.

Transoral Approach to the Jugular Foramen Region with Preservation of the Eustachian Tube

OBJECTIVES/HYPOTHESIS

Transnasal exposure of the jugular foramen region (JFR) often requires transection of the Eustachian tube (ET). This study aims to propose a transoral corridor for access to the JFR with preservation of the ET.

STUDY DESIGN

Cadaveric dissection and case illustration.

METHODS

An endoscopic transoral approach for exposure of the JFR was performed on 5 cadaveric specimens (10 sides). Six patients who underwent a transoral resection of schwannoma within the JFR were retrospectively analyzed.

RESULTS

Direct exposure of the JFR with a 0° scope via a transoral approach was feasible, and the internal carotid artery and lower cranial nerves could be adequately exposed, and preservation of the ET was achieved in all 10 sides of the cadaveric specimens. For six patients with JFR tumors, the transoral approach provided adequate access to achieve a gross total resection with ET preservation. Intraoperative cerebral spinal fluid (CSF) leak was encountered in one patient, and a multilayer reconstruction was employed for reconstruction. No operative field or intracranial infection, persistent CSF leak, or emergent airway issues occurred. No recurrence occurred in this cohort with an average follow-up of 12 months.

CONCLUSIONS

The transoral approach provided a reliable corridor for access into the JFR with preservation of the ET. For select lesions with expansion into the posterior cranial fossa, a transoral corridor may serve as an alternative for tumor extirpation.

LEVEL OF EVIDENCE

4 Laryngoscope, 2022.

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.

Intraoperative continuous vagus nerve monitoring with repetitive direct stimulation in surgery for jugular foramen tumors

OBJECTIVE

Surgery for tumors around the jugular foramen has significant risks of dysphagia and vocal cord palsy due to possible damage to the lower cranial nerve functions. For its treatment, long-term tumor control by maximum resection while avoiding permanent neurological damage is required. To accomplish this challenging goal, the authors developed an intraoperative continuous vagus nerve monitoring system and herein report their experience with this novel neuromonitoring method.

METHODS

Fifty consecutive patients with tumors around the jugular foramen (34 jugular foramen schwannomas, 11 meningiomas, 3 hypoglossal schwannomas, and 2 others) who underwent microsurgical resection under continuous vagus nerve monitoring within an 11-year period were retrospectively investigated. Evoked vagus nerve electromyograms were continuously monitored by direct 1-Hz stimulation to the nerve throughout the microsurgical procedure.

RESULTS

The average resection rate was 96.2%, and no additional surgery was required in any of the patients during the follow-up period (average 65.0 months). Extubation immediately after surgery and oral feeding within 10 days postoperatively were each achieved in 49 patients (98.0%). In 7 patients (14.0%), dysphagia and/or hoarseness were mildly worsened postoperatively at the latest follow-up, but tracheostomy or gastrostomy was not required in any of them. Amplitude preservation ratios on intraoperative vagus nerve electromyograms were significantly smaller in patients with postoperative worsening of dysphagia and/or hoarseness (cutoff value 63%, sensitivity 86%, specificity 79%).

CONCLUSIONS

Intraoperative continuous vagus nerve monitoring enables real-time and quantitative assessment of vagus nerve function and is important for avoiding permanent vagus nerve palsy, while helping to achieve sufficient resection of tumors around the jugular foramen.

Surgical Management of Jugular Foramen Schwannomas

Simple Summary

Treatments of jugular foramen schwannomas may be challenging due to critical anatomical relations and the involvement of different aspects of the skull base. Advances in microsurgery have led to improved outcomes over recent decades, whereas in contrast, some advocate stereotactic radiotherapy as an effective therapy, controlling the tumor volume with few complications. In this manuscript, we present the outcomes and adverse events in a contemporary cohort and discuss surgical advantages and disadvantages of different performed classic skull base approaches.

Abstract

Background: Resection of jugular foramen schwannomas (JFSs) with minimal cranial nerve (CN) injury remains difficult. Reoperations in this vital region are associated with severe CN deficits. Methods: We performed a retrospective analysis at a tertiary neurosurgical center of patients who underwent surgery for JFSs between June 2007 and May 2020. We included nine patients (median age 60 years, 77.8% female, 22.2% male). Preoperative symptoms included hearing loss (66.6%), headache (44.4%), hoarseness (33.3%), dysphagia (44.4%), hypoglossal nerve palsy (22.2%), facial nerve palsy (33.3%), extinguished gag reflex (22.2%), and cerebellar dysfunction (44.4%). We observed Type A, B, C, and D tumors in 3, 1, 1, and 4 patients, respectively. A total of 77.8% (7/9) underwent a retrosigmoid approach, and 33.3% (3/9) underwent an extreme lateral infrajugular transcondylar (ELITE) approach. Gross total resection (GTR) was achieved in all cases. The rate of shunt-dependent hydrocephalus was 22.2% (2/9). No further complications requiring surgical intervention occurred during follow-up. The median follow-up time was 16.5 months (range 3–84 months). Conclusions: Considering the satisfying outcome, the GTR of JFSs is feasible in performing well-known skull base approaches. Additional invasive and complicated approaches were not needed. Radiosurgery may be an effective alternative for selected patients.

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

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.

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.

Gross total resection of intracisternal accessory nerve schwannomas using a familiar midline suboccipital subtonsilar approach

Background

Intracisternal Accessory Nerve Schwannomas (ANS) constitute a rare clinical entity with only a few cases reported so far. Their symptoms are usually due to brainstem compression and not manifested until they render of great size. Secondary neuropathy and muscle atrophy are other late signs. The hitherto reported literature advocates a suboccipital craniotomy as a suitable approach. In most of the cases the spinal root was the location tumor arose from. Gross total resection was possible to be carried out in most cases with only sporadic tolerable postoperative deficits reported.

Case description

We hereby present three cases of patients with intracisternal ANS treated in the same fashion. Two patients were male and one female. Two patients complained of mainly chronic headaches and neck pain, whereas in the third patient the lesion was found incidentally. Only one patient suffered post-operatively cerebrospinal fluid leakage and wound healing complication, which was treated with revision surgery and administration of antibiotics. None of the patients had postoperative neurological deficits. Furthermore, we conducted a review of the relevant literature where we noted that there is no consensus yet with regards to the appropriate surgical approach.

Conclusions

Based on relevant anatomical studies, we advocate that suboccipital subtonsilar approach provides a wide corridor to the area of lesion allowing complete and safe resection of intracisternal ANS. We thus support that, in most cases, the neurosurgeon should consider using this familiar approach for treating this rare lesion.

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.

Gamma Knife Stereotactic Radiosurgery for Nonvestibular Cranial Nerve Schwannomas

BACKGROUND

Nonvestibular cranial schwannomas represent a rare type of benign intracranial tumor. Few studies have evaluated the use of stereotactic radiosurgery (SRS) as a primary management option for these lesions. We performed a retrospective review of our institution's experience focusing on efficacy with regard to tumor control and clinical symptom stabilization as well as treatment safety.

METHODS

Patients were included if they underwent at least 1 SRS procedure for a nonvestibular schwannoma and had at least 6 months of available imaging follow-up. Demographic, SRS dose planning, clinical, and imaging data were collected from chart reviews of treated patients. χ² and Kaplan-Meier analyses were performed.

RESULTS

Between 2004 and 2016, 35 schwannomas were treated in 34 patients. Median follow-up was 48 months. Median age at time of treatment was 51 years. Three patients had neurofibromatosis 2. Schwannoma location was trigeminal (57%), facial (20%), jugular foramen (14%), abducens (6%), and trochlear (3%). Median margin dose delivered was 13 Gy. The 5-year and 10-year tumor control rates were 94.4% and 88.5%, respectively. Presenting clinical symptoms stabilized or improved in 79% of cases after radiosurgery, and new or worsening symptoms were seen in 21%.

CONCLUSIONS

SRS is a safe and effective modality for treatment of nonvestibular cranial nerve schwannomas.

Optimal treatment of jugular foramen schwannomas: long-term outcome of a multidisciplinary approach for a series of 29 cases in a single institute

BACKGROUND

The goal of treatment for jugular foramen schwannomas (JFSs) is to achieve complete tumor removal with cranial nerve preservation. However, achieving this goal remains a challenge despite the advances in microsurgical techniques. The aim of this study was to determine optimal treatment strategies for JFSs based on a review of a series of 29 surgical cases in our institute.

MATERIALS AND METHODS

Between 1997 and 2013, 29 patients with JFSs underwent surgical treatment by multidisciplinary otoneurosurgical approaches. We retrospectively evaluated various clinical outcomes including the extent of tumor resection, postoperative cranial nerve deficits, and the recurrence rate. Tumor extension was classified using the Kaye and Pellet classification (KPC) system, and the extent of tumor resection was graded as gross total resection (GTR), near total resection (NTR), and subtotal resection (STR). We utilized the House-Brackmann facial nerve grading system (HBFNGS), the average pure-tone audiometry and speech audiometry (PTA/SA) tests, and the American Speech-Language-Hearing Association National Outcome Measurement System (ASHA NOMS) swallowing scale (ASHA level) for assessment of functional outcomes.

RESULTS

The extent of tumor resection was not related to the degree of immediate postoperative cranial nerve deficits. However, the surgical approach was significantly related to postoperative hearing status and immediate postoperative facial function. Also, among the ten patients who were below the level of acceptable facial function immediately postoperatively, nine patients (90%) recovered to acceptable facial function by the last follow-up. Concerning postoperative swallowing status, all 21 patients recovered swallowing function by the last follow-up. Postoperative Gamma Knife stereotactic radiosurgery (GKRS) was performed for three recurrent and seven residual tumors, and recurrence was not observed in the mean 36-month follow-up period.

CONCLUSIONS

A surgical strategy should be tailored to the individual case, and clinicians should consider the possibility of recurrence and further adjuvant treatment.

Dumbbell-Shaped Jugular Foramen Tumors Extending to the Neck: Surgical Considerations Based on Imaging Findings

OBJECTIVE

Dumbbell-shaped jugular foramen tumors (DSJFTs) extending to the neck present diagnostic and management difficulties because of their rarity, various pathologies, and multidisciplinary involvement. Accurate imaging findings are of great importance for surgical planning and clinical outcomes. However, few articles have discussed this issue to date.

METHODS

Thirty-one patients with DSJFTs extending to the neck were surgically treated in a single stage at our institute. Their clinical and radiologic features, operative procedures, and outcomes were retrospectively reviewed.

RESULTS

Preoperative correct diagnosis of DSJFTs extending to the neck was made in all cases of benign tumor and in only 3 cases of malignant tumors in this series. All tumors were removed via a craniocervical approach by a multidisciplinary skull base team because of both their intracranial and neck extensions. Total removal was achieved in 26 patients (83.9%). Preoperative symptoms were improved in 18 patients, whereas new or worsening lower cranial nerve deficits occurred in 4 patients postoperatively. Follow-up (1-132 months, mean 64.4 months) was available in 90.3% of the patients. No clinical or radiologic signs of tumor recurrence were observed.

CONCLUSIONS

Preoperative radiologic evaluation of DSJFTs extending to the neck is essential for differential diagnosis, patient selection, and surgical planning. Favorable surgical outcomes can be achieved via a craniocervical approach, and some detailed imaging findings are helpful to increase the safety of tumor resection and reduce the morbidity of lower cranial nerve deficits and cerebrospinal fluid leakage.

Cranial Nerve Schwannomas: Diagnostic Imaging Approach

Schwannomas are benign nerve sheath tumors that may arise along the complex course of the cranial nerves (CNs), anywhere in the head and neck. Sound knowledge of the CN anatomy and imaging features of schwannomas is paramount for making the correct diagnosis. In this article, we review approaches to diagnosing CN schwannomas by describing their imaging characteristics and the associated clinical presentations. Relevant anatomic considerations are highlighted by using illustrative examples and key differential diagnoses categorized according to regions, which include the anterior skull base, orbit, cavernous sinus, basal cisterns, and neck. The clinical presentations associated with CN schwannomas vary and range from no symptoms to symptoms caused by mass effect or CN deficits. Individuals with the inherited disorder neurofibromatosis type 2 are predisposed to multiple schwannomas. When a lesion follows the course of a CN, the radiologist's roles are to confirm the imaging features of schwannoma and exclude appropriate differential considerations. The characteristic imaging features of CN schwannomas reflect their slow growth as benign neoplasms and include circumscribed margins, displacement of local structures, and smooth expansion of osseous foramina. These neoplasms exhibit various degrees of solid enhancement, often with internal cystic spaces on magnetic resonance (MR) and computed tomographic (CT) images and heterogeneous high signal intensity specifically on T2-weighted MR images. Clinical and/or imaging evidence of end-organ compromise of the involved CN may exist and aid in the identification of the nerve of origin. With a detailed understanding of the course of the CNs, the diagnostic features of CN schwannomas, and the correlation between these data and the associated clinical presentations of these tumors, the radiologist can have a key role in the diagnosis of CN schwannomas and the treatment planning for affected patients. (©)RSNA, 2016.

Combined Endoscopic Transoral and Endonasal Approach to the Jugular Foramen: A Multiportal Expanded Access to the Clivus

BACKGROUND

The expanded endoscopic endonasal ("far medial") approach to the inferior clivus provides a unique surgical corridor to the ventral surface of the pontomedullary and cervicomedullary junctions. However, exposing neoplasms involving the jugular foramen (JF) through this approach requires extensive nasopharyngeal resection and lateral dissection beyond the boundaries of the endonasal corridor, limiting the extent of resection and restricting to use of this approach to expert surgeons. Here we describe a multiportal endoscopic transoral and endonasal approach to maximize surgical access to the JF and clivus.

METHODS

A multiportal endoscopic transoral and endoscopic approach to the JF and lower clivus was simulated in 8 specimens. A transoral corridor was created through a soft palate incision. The JF and parapharyngeal space were dissected through the transoral trajectory under endoscopic endonasal view. The length of the corridor of the transnasal and transoral trajectories was measured.

RESULTS

The JF was exposed intracranially and extracranially. The exposure extended superiorly to the sphenoid floor, inferiorly to the anterior atlanto-occipital space, and laterally to the internal acoustic meatus and parapharyngeal space. The cisternal parts of the cranial nerves VII-XII and C1 nerve bundles were accessible. Exposure of the JF contents and parapharyngeal space was possible using straight scopes, without Eustachian tube resection. The working corridor to the JF was significantly shorter through the mouth than through the nose (P < 0.0001).

CONCLUSIONS

This approach provides access to the JF from a ventromedial trajectory, enabling panoramic views, and outlines an expanded surgical exposure (superolateral intradural and inferolateral extracranial). It may provide optimal access for resection of dumbbell-shaped lesions of the JF.

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

OBJECTIVE This study aimed to explore the efficacy and safety of stereotactic radiosurgery in patients with jugular foramen schwannomas (JFSs). METHODS This study was a multiinstitutional retrospective analysis of 117 patients with JFSs who were treated with Gamma Knife surgery (GKS) at 18 medical centers of the Japan Leksell Gamma Knife Society. The median age of the patients was 53 years. Fifty-six patients underwent GKS as their initial treatment, while 61 patients had previously undergone resection. At the time of GKS, 46 patients (39%) had hoarseness, 45 (38%) had hearing disturbances, and 43 (36%) had swallowing disturbances. Eighty-five tumors (73%) were solid, and 32 (27%) had cystic components. The median tumor volume was 4.9 cm³, and the median prescription dose administered to the tumor margin was 12 Gy. Five patients were treated with fractionated GKS and maximum and marginal doses of 42 and 21 Gy, respectively, using a 3-fraction schedule. RESULTS The median follow-up period was 52 months. The last follow-up images showed partial remission in 62 patients (53%), stable tumors in 42 patients (36%), and tumor progression in 13 patients (11%). The actuarial 3- and 5-year progression-free survival (PFS) rates were 91% and 89%, respectively. The multivariate analysis showed that pre-GKS brainstem edema and dumbbell-shaped tumors significantly affected PFS. During the follow-up period, 20 patients (17%) developed some degree of symptomatic deterioration. This condition was transient in 12 (10%) of these patients and persistent in 8 patients (7%). The cause of the persistent deterioration was tumor progression in 4 patients (3%) and adverse radiation effects in 4 patients (3%), including 2 patients with hearing deterioration, 1 patient with swallowing disturbance, and 1 patient with hearing deterioration and hypoglossal nerve palsy. However, the preexisting hoarseness and swallowing disturbances improved in 66% and 63% of the patients, respectively. CONCLUSIONS GKS resulted in good tumor control in patients with either primary or residual JFSs. Although some patients experienced some degree of symptomatic deterioration after treatment, persistent adverse radiation effects were seen in only 3% of the entire series at the last follow-up. Lower cranial nerve deficits were extremely rare adverse radiation effects, and preexisting hoarseness and swallowing disturbances improved in two-thirds of patients. These results indicated that GKS was a safe and reasonable alternative to surgical resection in selected patients with JFSs.

A Single-Institution Retrospective Study of Jugular Foramen Schwannoma Management: Radical Resection Versus Subtotal Intracranial Resection Through a Retrosigmoid Suboccipital Approach Followed by Radiosurgery

BACKGROUND

Despite advances in skull base surgery, achieving effective surgical management of jugular foramen schwannomas (JFSs) that avoids postoperative cranial nerve (CN) deficits remains a challenge. Subtotal resection followed by radiosurgery (rather than radical resection) is increasingly being viewed as a better treatment strategy. Here, an institutional database was retrospectively analyzed for outcomes after surgical treatment of JFSs to evaluate the optimal strategy for managing JFSs.

METHODS

Twenty-two patients with JFSs were operated on by either radical resection (n = 13) or conservative resection plus radiosurgery (n = 9). These 2 different groups were compared in terms of early (≤4 weeks after surgery) and late postoperative functional outcome and oncologic control.

RESULTS

No deaths occurred in either group, but there were 3 surgery-related complications in the radical resection group. Postoperative CN deficits and additional procedures related to CN morbidity were generally higher in the radical resection group, but the differences were not statistically significant. The conservative surgery group showed a statistically significant improvement in the level of dysphagia and dysphagia-related functional state in the late postoperative period. There was 1 case of recurrence after radical resection over a mean follow-up period of 73 months. All tumors in the conservative surgery group were controlled over a mean period of 34 months.

CONCLUSIONS

Our results suggest that conservative resection of JFSs via a familiar intracranial approach plus radiosurgery may be an effective surgical alternative for improving functional outcome with adequate oncologic control.

Intracisternal cranial root accessory nerve schwannoma associated with recurrent laryngeal neuropathy

Intracisternal accessory nerve schwannomas are very rare; only 18 cases have been reported in the literature. In the majority of cases, the tumor origin was the spinal root of the accessory nerve and the tumors usually presented with symptoms and signs of intracranial hypertension, cerebellar ataxia, and myelopathy. Here, we report a unique case of an intracisternal schwannoma arising from the cranial root of the accessory nerve in a 58-year-old woman. The patient presented with the atypical symptom of hoarseness associated with recurrent laryngeal neuropathy which is noted by needle electromyography, and mild hypesthesia on the left side of her body. The tumor was completely removed with sacrifice of the originating nerve rootlet, but no additional neurological deficits. In this report, we describe the anatomical basis for the patient's unusual clinical symptoms and discuss the feasibility and safety of sacrificing the cranial rootlet of the accessory nerve in an effort to achieve total tumor resection. To our knowledge, this is the first case of schwannoma originating from the cranial root of the accessory nerve that has been associated with the symptoms of recurrent laryngeal neuropathy.

Case-control studies in neurosurgery

OBJECT

Observational studies, such as cohort and case-control studies, are valuable instruments in evidence-based medicine. Case-control studies, in particular, are becoming increasingly popular in the neurosurgical literature due to their low cost and relative ease of execution; however, no one has yet systematically assessed these types of studies for quality in methodology and reporting.

METHODS

The authors performed a literature search using PubMed/MEDLINE to identify all studies that explicitly identified themselves as "case-control" and were published in the JNS Publishing Group journals (Journal of Neurosurgery, Journal of Neurosurgery: Pediatrics, Journal of Neurosurgery: Spine, and Neurosurgical Focus) or Neurosurgery. Each paper was evaluated for 22 descriptive variables and then categorized as having either met or missed the basic definition of a case-control study. All studies that evaluated risk factors for a well-defined outcome were considered true case-control studies. The authors sought to identify key features or phrases that were or were not predictive of a true case-control study. Those papers that satisfied the definition were further evaluated using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist.

RESULTS

The search detected 67 papers that met the inclusion criteria, of which 32 (48%) represented true case-control studies. The frequency of true case-control studies has not changed with time. Use of odds ratios (ORs) and logistic regression (LR) analysis were strong positive predictors of true case-control studies (for odds ratios, OR 15.33 and 95% CI 4.52-51.97; for logistic regression analysis, OR 8.77 and 95% CI 2.69-28.56). Conversely, negative predictors included focus on a procedure/intervention (OR 0.35, 95% CI 0.13-0.998) and use of the word "outcome" in the Results section (OR 0.23, 95% CI 0.082-0.65). After exclusion of nested case-control studies, the negative correlation between focus on a procedure/intervention and true case-control studies was strengthened (OR 0.053, 95% CI 0.0064-0.44). There was a trend toward a negative association between the use of survival analysis or Kaplan-Meier curves and true case-control studies (OR 0.13, 95% CI 0.015-1.12). True case-control studies were no more likely than their counterparts to use a potential study design "expert" (OR 1.50, 95% CI 0.57-3.95). The overall average STROBE score was 72% (range 50-86%). Examples of reporting deficiencies were reporting of bias (28%), missing data (55%), and funding (44%).

CONCLUSIONS

The results of this analysis show that the majority of studies in the neurosurgical literature that identify themselves as "case-control" studies are, in fact, labeled incorrectly. Positive and negative predictors were identified. The authors provide several recommendations that may reverse the incorrect and inappropriate use of the term "case-control" and improve the quality of design and reporting of true case-control studies in neurosurgery.

Stereotactic radiosurgery for nonvestibular schwannomas

This article summarizes tumor control and functional outcomes of stereotactic radiosurgery (SRS) for patients with nonvestibular schwannomas, in comparison with those treated with microsurgical resection. To date, surgical resection has been a common treatment for nonvestibular schwannomas. Because these tumors are generally benign, complete tumor resection is a desirable curative treatment. However, it is almost infeasible to completely remove these tumors without any complications, even for experienced neurosurgeons, because of adherence to surrounding critical structures such as cranial nerves, brainstem, or vessels. SRS provides a good tumor control rate with much less morbidity than microsurgical resection.