Trigeminal schwannoma. Surgical series of 14 cases with review of the literature

Accessory nerve schwannoma extending into the fourth ventricle: case report and review of literature

Accessory nerve schwannoma is a rare entity in patients presenting with cranial nerve (CN) deficits. Most of these tumours arise from the cisternal segment of the eleventh CN and extend caudally. Herein, we report the third case of an accessory schwannoma extending cranially into the fourth ventricle. A 61-year-old female presented with a history of variable headaches. Cerebral magnetic resonance imaging (cMRI) revealed a large inhomogeneous contrast-enhancing lesion at the craniocervical junction extending through the foramen of Magendi and concomitant hydrocephalus due to obstruction of the foramina of Luschkae. Microsurgical tumour resection was performed in the half-sitting position. Intraoperatively, the tumour arose from a vestigial fascicle of the spinal accessory nerve. At three month follow-up, neither radiological tumour recurrence nor neurological deficits were observed.

Microsurgical Resection Versus Stereotactic Radiosurgery for Trigeminal Schwannoma: A Meta-Analysis of 949 Patient Treatment Outcomes

BACKGROUND AND OBJECTIVES

Schwannomas are benign, slow-growing peripheral nerve sheath tumors. Approximately 8% of intracranial schwannomas originate from the trigeminal nerve. No consensus exists regarding superiority of outcomes after resection vs stereotactic radiosurgery (SRS) in the treatment of trigeminal schwannomas (TS). The aim of this study was to compare the efficacy and outcomes of resection vs SRS for TS management.

METHODS

Embase, PubMed, and SCOPUS databases were queried from the date of inception to July 2023 for primary data reporting TS treatment outcomes after SRS or resection. Risk of bias was reported under Newcastle-Ottawa Scale.

RESULTS

Overall, 29 retrospective observational studies comprising 949 patients were included in the analysis. A total of 13 studies (n = 589) reported outcomes after SRS, and 16 studies (n = 360) reported outcomes after surgical resection, and 182 patients in the SRS group had previous resection. To ensure statistical validity of comparing the cohorts, 3 checkpoints were assessed: the median age (SRS: 48 vs surgery: 40 years old, P < .01), tumor volume (5.2 vs 8.9 cm3, P = .06), and median follow-up (53.9 vs 48.5 months, P = .59), which reflected the choice of treatment. Compared with surgical resection, the SRS group demonstrated significantly higher rates of facial hypesthesia improvement (44% vs 12%, P < .01) and lower rates of new onset (4% vs 15%, P = .051) at last follow-up. Facial pain was less likely to improve (58% vs 81%, P = .024) after SRS compared with surgery. However, worsened (5% vs 1%, P = .71) and new facial pain (2% vs 1%, P = .55) were comparable between cohorts.

CONCLUSION

SRS seems to offer improvement in rates of hypesthesia and trigeminal motor deficits compared with surgical resection for TS. However, facial pain improvement was more favorable after surgery. These findings highlight the importance of individualized treatment decisions based on patient characteristics, tumor profile, and pretreatment symptoms.

Management of large Trigeminal Schwannoma: long-term oncologic and functional outcome from a multicentric retrospective cohort

OBJECTIVE

Trigeminal schwannoma (TS), though a rare and benign tumor, becomes a significant surgical challenge due to its intricate location. This study aims to detail the long-term functional outcomes and tumor control post-surgical resection.

METHOD

We analyzed a multicentric retrospective cohort of 39 patients operated on for a TS in five tertiary centers between January 1993 and July 2022.

RESULTS

Six TS (15%) were in the middle fossa (type M), two (5%) in the posterior fossa (type P), and two (5%) were extracranial (type E). Twenty-nine (75%) were Dumbbell shape: Eighteen (47%) were MP type, seven (18%) were MPE type, and four (10%) were ME type. Fifth nerve symptoms were the foremost preoperative complaint: hypesthesia (51%), trigeminal neuralgia (36%), and paresthesia (30%). We report a favorable evolution course for 61% of preexisting deficits (half of patients with preoperative paresthesia and neuralgia improved while only 5% of preoperative hypesthesia improved). Postoperative hypesthesia was the most frequent de novo deficit 14 (74%) and resolved in solely half the cases. Various approaches were used according to tumor type. Gross total resection (GTR), Subtotal resection (STR), and partial resection (PR) were achieved in respectively 33% (N = 13), 10% (N = 4), and 56% (N = 22) of patients. The mean clinical and radiological FU was 63 months (12 - 283 months). GTR led to no sign of recurrence (mean FU: 60 months - range: 12-283 months). For STR or PR (67%): 23 (88%) were assigned to a Wait-&-rescan policy (WS group) which offered stability in 70% (N = 16). Three cases (8%) underwent a complementary GKS (GammaKnife) on the residual lesion (GK group) without tumor change.

CONCLUSION

For large TS, the completeness of resection must consider the potential functional burden of surgery. With giant infiltrating lesions, a strategy of planned subtotal resection, complemented by radiosurgery, either complementary or uppon regrowth, may provide similar oncological outcomes.

Preservation of cranial nerve function in large and giant trigeminal schwannoma resection: a case series

BACKGROUND

Trigeminal schwannomas (TSs) are intracranial tumors that can cause significant brainstem compression. TS resection can be challenging because of the risk of new neurologic and cranial nerve deficits, especially with large (≥ 3 cm) or giant (≥ 4 cm) TSs. As prior surgical series include TSs of all sizes, we herein present our clinical experience treating large and giant TSs via microsurgical resection.

METHODS

This was a retrospective, single-surgeon case series of adult patients with large or giant TSs treated with microsurgery in 2012-2023.

RESULTS

Seven patients underwent microsurgical resection for TSs (1 large, 6 giant; 4 males; mean age 39 ± 14 years). Tumors were classified as type M (middle fossa in the interdural space; 1 case, 14%), type ME (middle fossa with extracranial extension; 3 cases, 43%), type MP (middle and posterior fossae; 2 cases, 29%), or type MPE (middle/posterior fossae and extracranial space; 1 case, 14%). Six patients were treated with a frontotemporal approach (combined with transmastoid craniotomy in the same sitting in one patient and a delayed transmaxillary approach in another), and one patient was treated using an orbitofrontotemporal approach. Gross total resection was achieved in 5 cases (2 near-total resections). Five patients had preoperative facial numbness, and 6 had immediate postoperative facial numbness, including two with worsened or new symptoms. Two patients (28%) demonstrated new non-trigeminal cranial nerve deficits over mean follow-up of 22 months. Overall, 80% of patients with preoperative facial numbness and 83% with facial numbness at any point experienced improvement or resolution during their postoperative course. All patients with preoperative or new postoperative non-trigeminal tumor-related cranial nerve deficits (4/4) experienced improvement or resolution on follow-up. One patient experienced tumor recurrence that has been managed conservatively.

CONCLUSIONS

Microsurgical resection of large or giant TSs can be performed with low morbidity and excellent long-term cranial nerve function.

Clinical and Imaging Outcomes After Trigeminal Schwannoma Radiosurgery: Results From a Multicenter, International Cohort Study

BACKGROUND AND OBJECTIVES

An international, multicenter, retrospective study was conducted to evaluate the long-term clinical outcomes and tumor control rates after stereotactic radiosurgery (SRS) for trigeminal schwannoma.

METHODS

Patient data (N = 309) were collected from 14 international radiosurgery centers. The median patient age was 50 years (range 11-87 years). Sixty patients (19%) had prior resections. Abnormal facial sensation was the commonest complaint (49%). The anatomic locations were root (N = 40), ganglion (N = 141), or dumbbell type (N = 128). The median tumor volume was 4 cc (range, 0.2-30.1 cc), and median margin dose was 13 Gy (range, 10-20 Gy). Factors associated with tumor control, symptom improvement, and adverse radiation events were assessed.

RESULTS

The median and mean time to last follow-up was 49 and 65 months (range 6-242 months). Greater than 5-year follow-up was available for 139 patients (45%), and 50 patients (16%) had longer than 10-year follow-up. The overall tumor control rate was 94.5%. Tumors regressed in 146 patients (47.2%), remained unchanged in 128 patients (41.4%), and stabilized after initial expansion in 20 patients (6.5%). Progression-free survival rates at 3 years, 5 years, and 10 years were 91%, 86%, and 80 %. Smaller tumor volume (less than 8 cc) was associated with significantly better progression-free survival ( P = .02). Seventeen patients with sustained growth underwent further intervention at a median of 27 months (3-144 months). Symptom improvement was noted in 140 patients (45%) at a median of 7 months. In multivariate analysis primary, SRS ( P = .003) and smaller tumor volume ( P = .01) were associated with better symptom improvement. Adverse radiation events were documented in 29 patients (9%).

CONCLUSION

SRS was associated with long-term freedom (10 year) from additional management in 80% of patients. SRS proved to be a valuable salvage option after resection. When used as a primary management for smaller volume tumors, both clinical improvement and prevention of new deficits were optimized.

Comparative Analysis of Surgical Working Corridors for Meckel Cave Trigeminal Schwannomas: A Quantitative Anatomic Study

BACKGROUND AND OBJECTIVES

Volumetric analysis of the working corridors of the interdural approach to the Meckel cave may lead to a selection of routes which are anatomically more advantageous for trigeminal schwannoma resection. The herein-reported anatomic study quantitively compares the infratrochlear (IT) transcavernous, anteromedial (AM), and anterolateral (AL) corridors, highlighting their feasibility, indications, advantages, and limitations.

METHODS

Anatomic boundaries and depth of Meckel cave, porus trigeminus, IT transcavernous, AM, and AL corridors were identified in 20 formalin-fixed latex-injected cadaveric heads and were subsequently measured. The corridor areas and volumes were derived accordingly. Each opening angle was also calculated. Angles and volumes were compared using analysis of variance. Statistical significance was set at a P -value <.05.

RESULTS

The IT transcavernous corridor volume was greater than that of the AM and AL. The opening angle of the AM middle fossa triangle was wider than the other 2.

CONCLUSION

The IT corridor can be advantageous for Meckel cave schwannomas invading the cavernous sinus and those with a notable extension into the posterior fossa because the transcavernous approach maximizes the working space into the retrosellar area. The AM middle fossa corridor is strategic in schwannomas confined to the Meckel cave with a minor extension into the posterior fossa. It raises the chance of total resection with a single approach involving the porus trigeminus opening.

Outcomes following surgical resection of trigeminal schwannomas: a systematic review and meta-analysis

Although typically benign, trigeminal schwannomas (TS) may require surgical resection when large or symptomatic and can cause significant morbidity. This study aims to summarize the literature and synthesize outcomes following surgical resection of TS. A systematic review was performed according to PRISMA guidelines. Data extracted included patient and tumor characteristics, surgical approaches, and postoperative outcomes. Odds ratios (OR) with corresponding 95% confidence intervals (CI) were used for outcome analysis. The initial search yielded 1838 results, of which 26 studies with 974 patients undergoing surgical resection of TS were included. The mean age was 42.9 years and 58.0% were female. The mean tumor diameter was 4.7 cm, with Samii type A, B, C, and D tumors corresponding to 33.4%, 15.8%, 37.2%, and 13.6%, respectively. Over a mean symptom duration of 29 months, patients presented with trigeminal hypesthesia (58.7%), headache (32.8%), trigeminal motor weakness (22.8%), facial pain (21.3%), ataxia (19.4%), diplopia (18.7%), and visual impairment (12.0%). Surgical approaches included supratentorial (61.4%), infratentorial (15.0%), endoscopic (8.6%), combined/staged (5.3%), and anterior (5.7%) or posterior (4.0%) petrosectomy. Postoperative improvement of facial pain (83.9%) was significantly greater than trigeminal motor weakness (33.0%) or hypesthesia (29.4%). The extent of resection (EOR) was reported as gross total (GTR), near total, and subtotal in 77.7%, 7.7%, and 14.6% of cases, respectively. Over a mean follow-up time of 62.6 months, recurrence/progression was noted in 7.4% of patients at a mean time to recurrence of 44.9 months. Patients with GTR had statistically significantly lower odds of recurrence/progression (OR: 0.07; 95% CI: 0.04-0.15) compared to patients with non-GTR. This systematic review and meta-analysis report patient outcomes following surgical resection of TS. EOR was found to be an important predictor of the risk of recurrence. Facial pain was more likely to improve postoperatively than facial hypesthesia. This work reports baseline rates of post-operative complications across studies, establishing benchmarks for neurosurgeons innovating and working to improve surgical outcomes for TS patients.

Trigeminal Schwannoma - Case Report of a Rare Tumour

Schwannomas are benign nerve tumours arising from the Schwann cells. Approximately 25-45% of schwannomas occurs in the head and neck region. Majority of schwannomas in the head and neck region arise from the vagus nerve. Trigeminal schwannomas account for about 0.2% of all intracranial tumours. Trigeminal schwannomas can originate from any section of the fifth cranial nerve, from the root to the distal extracranial branches, but majority develops from the Gasserian ganglion, usually growing in the middle cranium. Most common presenting symptom is facial pain. MRI is the imaging modality of choice and CT scan usually serves as a supplementary imaging especially for skull base tumours. 47 year old male patient presented to the outpatient department with complains of swelling over the left side of palate. Contrast enhanced CT scan demonstrated a large bilobed heterogeneously enhancing soft tissue lesion in the left infratemporal fossa with widened foramen ovale and extension of lesion into the Meckel's cave, larger contiguous component extending into ramus of mandible. MRI scan showed a large lobulated mass in the left masticator space with intracranial extension. Biopsy of the lesion was suggestive of schwannoma. The patient underwent left composite resection with dural repair and free flap reconstruction. Post operatively, on day 5 he developed features of meningitis for which he was treated conservatively and later discharged in stable condition. Trigeminal schwannomas are rare tumours with very low chance of malignant transformation which commonly presents with facial pain. MRI is the imaging modality of choice. Complete surgical excision is the treatment of choice.

A Case of Malignant Melanotic Schwannoma of the Trigeminal Nerve: A Case Report and Review of Literature

Intracranial melanotic schwannoma is quite rare, and involvement of the trigeminal nerve is even rarer. Early diagnosis and surgical excision are the mainstays of management. These tumors have a high tendency to recur and there is high possibility of metastasis. Adjuvant radiotherapy should be considered since the prognosis is uncertain. A 23-year-old man started developing numbness over the left side of the forehead 9 months ago that progressed to involve the ipsilateral cheek. The patient started having diplopia on looking to the left side 8 months ago. His relatives noticed a change in his voice 1 month ago and he developed weakness in the right upper and lower limbs, which was gradually progressive. The patient had slight difficulty swallowing. After examination, we found involvement of multiple cranial nerves with pyramidal signs. Magnetic resonance imaging (MRI) was suggestive of an extra-axial lesion in the left cerebellopontine angle extending into the middle cranial fossa, which was having high T1 and T2 signal loss with contrast enhancement. We achieved near-total excision of the tumor via a subtemporal extradural approach. Trigeminal melanotic schwannoma is a rare occurrence constituting melanin-producing cells and Schwann cells. Rapid progression of symptoms and signs should prompt the suspicion of the possible malignant nature of the pathology. Extradural skull base approaches reduce the risk of postoperative deficits. Differentiating melanotic schwannoma from malignant melanoma is of utmost importance in planning of management.

Hybrid endoscopic-microscopic surgery for dumbbell-shaped trigeminal schwannoma: case report and literature review

Background

The surgery of dumbbell-shaped trigeminal neurinomas (TN) remains one of the most formidable challenges for neurosurgeons because of its location at great depth in the cranium and proximity to vital neurovascular structures.

Objective

To describe the feasibility of a novel technique, synchronous endoscopy and microsurgery via combined far-lateral supracerebellar-infratentorial and subtemporal approach, for resection of this rare entity.

Methods

A 53-year-old women presented with progressive left facial numbness for 2 months. Imaging examinations revealed a left-sided dumbbell-shaped TN afflicting the middle and posterior cranial fossa, and a single-stage combined multiportal endoscopic microscopic approach was attempted for tumor resection. Initially, a purely endoscopic far-lateral supracerebellar-infratentorial approach was used to remove the posterior fossa component with the aid of tentorium incision. Subsequently, a microsurgical subtemporal interdural approach was performed for the exposure and separation of tumor within the Meckel cave. Finally, the tumor was pushed into the porus trigeminus under microscopy, thus enabling tumor extraction for the supracerebellar space under endoscopy without anterior petrosectomy.

Results

The patient evolved favorably without additional neurological deficit after surgery, and postoperative imaging showed a complete resection of the tumor.

Conclusion

We describe the first account of multi-corridor hybrid surgery for removal of TN in a dumbbell configuration, which enables one-stage total tumor removal with minimal added morbidity. This hybrid technique may be an effective piece of the surgeon's armamentarium to improve outcomes of patient with complex skull-base lesions. Further studies with larger case numbers are warranted to confirm the prognostic significance of this technique.

Thirty-year clinical experience in gamma knife radiosurgery for trigeminal schwannomas

We aimed to evaluate the radiographic and clinical outcomes after gamma knife radiosurgery (GKRS) for trigeminal schwannomas (TSs). A total of 87 patients who underwent GKRS for TSs between 1990 and 2020 were enrolled. The mean tumor volume was 4.3 cm³. The median prescribed dose for the margins of the tumor was 13 Gy. The median follow-up duration was 64.3 months (range 12.0–311.5 months). The overall local tumor control rate was 90%, and the symptom response rate was 93%. The response rate for each symptom was 88% for facial pain, 97% for facial sensory change, and 86% for cranial nerve deficits. Nineteen (22%) patients showed transient swelling, which had regressed at the time of the last follow-up. Cystic tumors were associated with transient swelling (p = 0.04). A tumor volume of < 2.7 cm³ was associated with local tumor control in univariable analysis. Transient swelling was associated with symptom control failure in both univariable and multivariable analyses (p = 0.04, odds ratio 14.538). GKRS is an effective treatment for TSs, both for local control and symptom control.

Dumbbell-shaped meningioma of Meckel's cave mimicking trigeminal schwannoma: A case report

INTRODUCTION AND IMPORTANCE

Several meningioma cases arising through Meckel's cave (MC) at the middle and posterior fossa have been reported. However, few relevant meningiomas have been observed with a dumbbell shape.

PRESENTATION OF CASE

We report a rare case of a 36-year-old woman with a meningioma of MC with a typical dumbbell-shaped, schwannoma-like presentation on magnetic resonance imaging (MRI), resulting in a misleading differential diagnosis.

CLINICAL DISCUSSION

In this case report, we discuss the characteristics of meningioma of MC observed on MRI and our surgical approach to this condition.

CONCLUSION

This tumor was able to mimic a trigeminal schwannoma both clinically and radiographically. This case report has been reported in line with the SCARE 2020 criteria [1].

Gamma knife radiosurgery for trigeminal schwannomas: A systematic review and meta-analysis

BACKGROUND

Gamma knife radiosurgery (GKRS) has been deemed as the gold standard stereotactic radiosurgery (SRS) mode for the treatment of intracranial tumors, cerebrovascular diseases and brain functional diseases. Our study was aimed to systematically evaluate the efficacy, safety, and complications of gamma knife radiosurgery for trigeminal schwannomas.

METHOD

We performed a systematic review and meta-analysis to analyze the clinical outcomes of patients with trigeminal schwannomas treated primarily or adjunctly with GKRS. We searched two databases, Pubmed and Embase, for studies published before January 1, 2021, using GKRS for trigeminal schwannomas. Studies reporting treatment of other schwannomas, or other forms of SRS such as linear accelerator and Cyberknife were excluded to reduce its heterogeneity.

RESULTS

Our search achieved 351 studies, of which 35 were assessed for full-text eligibility. 19 studies were included in the meta-analysis. 456 of 504 patients (0.94, 95% CI 0.91-0.96, I² = 3.02%, p < 0.01) from 18 studies had local control, and 278 of 489 patients (0.63, 95%CI 0.48-0.78, I² = 88.75%, p < 0.01) from 16 studies experienced tumor regression or disappearance. 231 of 499 patients (0.50, 95% CI 0.37-0.62; I² = 83.89%, P < 0.01) from 17 studies had clinical symptoms improved. There was no significant difference in tumor control between those treated with GKRS as either primary treatment or adjuvant to surgery(p = 0.390).

CONCLUSION

GKRS is an efficacious primary and adjuvant method of treating trigeminal schwannomas, with reliable tumor control rates. Randomized controlled trials are needed to further and comprehensively evaluate the benefit-to-risk ratio of gamma knife radiosurgery.

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.

Long-term outcomes of stereotactic radiosurgery for skull base tumors involving the cavernous sinus

PURPOSE

Stereotactic radiosurgery (SRS) is an effective and less invasive therapeutic option for cavernous sinus (CS) tumors. However, its long-term effectiveness and neurological outcomes have yet to be fully elucidated. We aimed to examine the long-term outcomes of SRS for CS tumors.

METHODS

Overall, a cohort of 113 patients with benign CS tumors, including 91 with meningioma, 14 with trigeminal schwannoma (TS), and eight with cavernous hemangioma, treated with SRS at our institution from 1990 to 2018, was included. Tumor control and functional preservation/recovery were evaluated in detail.

RESULTS

The median post-SRS follow-up period was 77 months (interquartile range, 39-177). Progression-free survival (PFS) was 97% at 5 years, 89% at 10 years, and 87% at 15 years for the entire cohort; 96% at 5 years and 87% at 10 years for meningiomas; and 100% at 10 years for the other tumors. No significant difference was observed between meningiomas and non-meningiomas (log-rank test, p = 0.107). Improvement in cranial nerve (CN) function was observed in 35 (27%) patients. TSs tended to show CN improvements more often than meningiomas did (total improvements, 62% vs. 23%; p = 0.004; eye movement function, 100% vs. 20%; p = 0.002). CN deterioration or development of new CN deficits was observed in 11 (10%) patients.

CONCLUSION

SRS provides good tumor control and acceptable long-term outcome with sufficient preservation of CN function in patients with benign CS tumors.

Clinical and Imaging Response to Trigeminal Schwannoma Radiosurgery: A Retrospective Analysis of a 28-Year Experience

Objective  The purpose of this study was to evaluate long-term clinical outcomes and tumor control after stereotactic radiosurgery (SRS) for trigeminal schwannoma (TS). Methods  During a 28-year period (1989-2017), 50 patients underwent SRS for TS. The median patient age was 51 years (range: 15-87 years). A total of 17 patients had a previous tumor resection: 10 had a single procedure, 5 had two procedures, and 2 had three procedures. The median and mean times between tumor resection and SRS were 12 and 24 months (range: 1-90 months), respectively. Four patients had neurofibromatosis II (NF2). Based on location, tumors were classified as root type (7), ganglion type (22), or dumbbell type (21). The median radiosurgery target volume was 3.4 cm ³ (range: 0.10-18 cm ³ ), median target dose was 14 Gy (range: 12-20 Gy), and the median number of isocenters was 6 (range: 1-15). The median and mean times to last follow-up was 36.9 and 55.2 months (range: 4-205 months), respectively. Eighteen patients (36%) had longer than 5-year follow-up, and seven patients (14%) had longer than 10-year follow-up. Results  The tumor control rate was 92% and the clinical improvement or stabilization rate was 94%. After SRS, the rates of progression free survival (PFS) at 1, 5, and 10 years were 98, 84, and 84%, respectively. Factors associated with improved PFS were female sex ( p  = 0.014) and smaller tumor volume ( p  = 0.022). In this series, we did not find that tumor type (root, ganglion, and dumbbell) had a statistically significant correlation to PFS. Forty-seven patients had neurological signs or symptoms at presentation. At last follow-up, neurological signs or symptoms improved in 22/47 (47%), remained unchanged in 24/50 (48%), and worsened due to tumor progression in 3/50 (6%). One patient (2%) developed temporary symptomatic adverse radiation effect (ARE) and three additional patients (6%) had transient imaging evidence of peritumoral reactive edema but no new symptoms. Conclusion  As a single outpatient procedure, SRS was associated with long-term freedom from additional management in 84% of patients. Nearly half the treated patients experienced improvement in neurological symptoms or signs.

Double-Stage Complete Removal of Dumbbell-Shaped Trigeminal Schwannoma: 3-Dimensional Operative Video

Intracranial trigeminal schwannomas are rare tumors.1-4 The aim of this 3-dimensional operative video is to present a double stage complete removal of a dumbbell-shaped trigeminal schwannoma. This is a 25-yr-old male with headaches, diplopia, and facial pain. The MRI shows a big tumor located at the level of the cerebellopontine angle, petroclival region, and middle fossa. Because of the size of the tumor and its growth within the cerebellopontine angle, we decided to operate the patient in two stages. For the first surgery, the patient was in a semi-sitting position, and a retrosigmoid approach was performed. The second surgery was performed 2 mo after the first operation in a supine position for a pretemporal transzygomatic approach. The pathological study was reported as a schwannoma, and the histological findings were spindle cell lesion with a storiform pattern and histiocytes. The patient evolved without neurological deficit after the surgeries, and the postoperative MRI shows a complete resection of the tumor. The patient gave the consent to use the images and surgical video. Preoperative imaging plays an important role in diagnosis and surgical planning.3-6 For these cases of trigeminal schwannomas with a large extension in the posterior fossa and middle fossa, we believe that the most prudent thing is to perform the surgery in 2 stages.3.

Pediatric multicompartmental trigeminal schwannoma: illustrative case

BACKGROUND

Trigeminal schwannoma (TS) is an uncommon and histologically benign intracranial lesion that can involve any segment of the fifth cranial nerve. Given its often impressive size at diagnosis and frequent involvement of critical neurovascular structures of the skull base, it represents a challenging entity to treat. Pediatric TS is particularly rare and presents unique challenges. Similarly, tumors with extension into multiple compartments (e.g., middle cranial fossa, posterior cranial fossa, extracranial spaces) are notoriously difficult to treat surgically. Combined or staged surgical approaches are typically required to address them, with radiosurgical treatment as an adjunct.

OBSERVATIONS

The authors presented the unusual case of a 9-year-old boy with a large, recurrent multicompartmental TS involving Meckel’s cave, the cerebellopontine angle, and the infratemporal fossa. Near-total resection was achieved using a frontotemporal-orbitozygomatic craniotomy with a combined interdural and extradural approach.

LESSONS

The case report adds to the current literature on multicompartmental TSs in children and their management. The authors also provided a simplified classification of TS that can be generalized to other skull base tumors. Given a lack of precedent, the authors intended to add to the discussion regarding surgical management of these rare and challenging skull base lesions.

Tumor control and trigeminal dysfunction improvement after stereotactic radiosurgery for trigeminal schwannomas: a systematic review and meta-analysis

Trigeminal nerve schwannomas (TS) are uncommon intracranial tumors, frequently presenting with debilitating trigeminal and/or oculomotor nerve dysfunction. While surgical resection has been described, its morbidity and mortality rates are non-negligible. Stereotactic radiosurgery (SRS) has emerged with variable results as a valuable alternative. Here, we aimed at reviewing the medical literature on TS treated with SRS so as to investigate rates of tumor control and symptomatic improvement. We reviewed manuscripts published between January 1990 and December 2019 on PubMed. Tumor control and symptomatic improvement rates were evaluated with separate meta-analyses. This meta-analysis included 18 studies comprising a total of 564 patients. Among them, only one reported the outcomes of linear accelerators (Linac), while the others of GK. Tumor control rates after SRS were 92.3% (range 90.1–94.5; p < 0.001), and tumor decrease rates were 62.7% (range 54.3–71, p < 0.001). Tumor progression rates were 9.4% (range 6.8–11.9, p < 0.001). Clinical improvement rates of trigeminal neuralgia were 63.5% (52.9–74.1, p < 0.001) and of oculomotor nerves were 48.2% (range 36–60.5, p < 0.001). Clinical worsening rate was 10.7% (range 7.6–13.8, p < 0.001). Stereotactic radiosurgery for TS is associated with high tumor control rates and favorable clinical outcomes, especially for trigeminal neuralgia and oculomotor nerves. However, patients should be correctly advised about the risk of tumor progression and potential clinical worsening. Future clinical studies should focus on standard reporting of clinical outcomes.

Disuse atrophy of masticatory muscles after intracranial trigeminal schwannoma resection: A case report and review of literature

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Temporomandibular disorders (TMD) are diseases of the temporomandibular joint and masticatory muscles, and are often difficult to be diagnosed.

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Determining the cause of facial asymmetry and jaw deviation are quite challenging.

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The morphologic and functional characteristics of masticatory muscles are maintained by sensory and motor innervation from the trigeminal nerve.

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Trigeminal schwannoma is a rare benign tumor originating from the Schwann cells.

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We experienced a case of masticatory muscle disuse atrophy during long-term follow-up after resection of intracranial trigeminal schwannoma.

Introduction

Temporomandibular disorders (TMD) are diseases of the temporomandibular joint and masticatory muscles, and are often difficult to be diagnosed because they have various symptoms, pathological conditions and causes.

Presentation of case

Herein, we report a 78-year-old male referred to our hospital with a diagnosis of TMD and presenting with facial asymmetry, marked deviation to the right side on vertical mandibular movement and complaints of abnormal perception at the right oral and buccal region. Past medical history revealed that he had undergone a right intracranial trigeminal schwannoma resection 9 years prior. Computed tomography (CT) showed disuse atrophy of the right side of 4 masticatory muscles and 2 suprahyoid muscles controlled by the motor component of the mandibular division (V3) of the trigeminal nerve (TGN). Together with the neurosurgeon, we confirmed that there was no recurrence of the tumor and explained to the patient that the oral and maxillofacial symptoms are after-effects of the operation, and we provided oral hygiene instructions and coordinated cleaning of the inside of the oral cavity.

Discussion

Although it is difficult to compare treatment methods from case to case, we believe that in our case, the patient's understanding of the cause of his discomfort contributed significantly to the improvement of his quality of life.

Conclusion

We experienced a case of masticatory muscle disuse atrophy during long-term follow-up after resection of intracranial trigeminal schwannoma. Further studies are needed to develop the diagnostic and therapeutic protocols for disuse atrophy.

Trigeminal schwannoma presenting with malocclusion: A case report and review of the literature

BACKGROUND

Trigeminal schwannomas are rare tumors of the trigeminal nerve. Depending on the location, from which they arise along the trigeminal nerve, these tumors can present with a variety of symptoms that include, but are not limited to, changes in facial sensation, weakness of the masticatory muscles, and facial pain.

CASE DESCRIPTION

We present a case of a 16-year-old boy with an atypical presentation of a large trigeminal schwannoma: painless malocclusion and unilateral masticatory weakness. This case is the first documented instance; to the best of our knowledge, in which a trigeminal schwannoma has led to underbite malocclusion; it is the 19th documented case of unilateral trigeminal motor neuropathy of any etiology. We discuss this case as a unique presentation of this pathology, and the relevant anatomy implicated in clinical examination aid in further understanding trigeminal nerve pathology.

CONCLUSION

We believe our patient's underbite malocclusion occurred secondary to his trigeminal schwannoma, resulting in associated atrophy and weakness of the muscles innervated by the mandibular branch of the trigeminal nerve. Furthermore, understanding the trigeminal nerve anatomy is crucial in localizing lesions of the trigeminal nerve.

SIMULTANEOUS REMOVAL OF THE NEURINOMA OF THE TRIPLE NERV, LOCALIZED IN THE BACK, MIDDLE, AND SECULAR PITS. CLINICAL OBSERVATION AND REVIEW OF LITERATURE

The aim of the study is to consider and show the possibilities of methods for surgery of skull base tumors using the example of successful surgical treatment of a patient with widespread trigeminal neuroma located in the posterior, middle and temporal fossae, as well as to analyze international scientific experience on this issue. Materials and methods. In February 2020, a 60-year-old patient with widespread trigeminal neuroma on the left was admitted to the Federal Scientific-Clinical Center of FMBA of Russia in February 2020. After additional examination and preoperative preparation, a planned operation was performed - osteoplastic orbitozygomatic trepanation of the skull, microsurgical removal of the tumor through subtemporal transcavernous access. A good postoperative clinical result was obtained. An analysis of the available scientific literature on this problem is carried out. Results. In the postoperative period, pain and neurological symptoms, hemifacial spasm completely regressed. 1.5 months after the operation, the tumor was totally removed in the control images. In the course of the analysis of available foreign and domestic literature, 65 observations of trigeminal tumors with extracranial growth were found, the total removal of which was performed only in 20% of patients. Conclusion. Despite the extreme complexity of the pathology, the operation through the orbitozygomatic subtemporal transcavernous access allows you to completely remove the common and giant trigeminal neuromas with a good functional result.

Trigeminal schwannoma: a single-center experience with 43 cases and review of literature

OBJECTIVE

Trigeminal schwannomas (TS) are rare, when compared to vestibular schwannomas. The present study aims to analyze the clinical characteristics and surgical strategies of TS via the retrospective analysis of the clinical data of 43 patients.

METHODS

The clinical information of 43 patients diagnosed with TS, who were surgically treated from January 2008 to January 2018, was retrospectively analyzed. Then, the selection of approaches and surgical strategies were discussed.

RESULTS

During the last 10 years, 43 patients with TS received surgical treatment at Xuan Wu Hospital of Capital Medical University. Facial numbness and hypoesthesia were the most common symptoms, which developed in 29 cases (67.4%). Typical trigeminal neuralgia was complained by four patients (9.3%), while trigeminal motor impairment developed in nine cases (20.9%). The tumor was totally removed in 39 patients (90.7%), near-totally removed in three patients (7.0%), and partially removed in one patient (2.3%) due to intraoperative internal carotid artery (ICA) injury. The abducens was intraoperatively damaged in two patients (4.7%). After the operation, all four patients with trigeminal neuralgia achieved total recovery, but the facial numbness still continued in 24 patients (82.8%). At a median of 45.3 ± 25.5 (6-84) months of follow up, a tumor recurred in only one patient, and this patient received a second operation.

CONCLUSION

It can be concluded that total removal via the proper approach can be the best treatment for TS with a low complication rate. However, preoperative symptoms, such as facial numbness and trigeminal motor impairment that seldom improved though normal fibers, were carefully recognized and preserved during the operation.

Cystic trigeminal schwannomas

Trigeminal Schwannomas are less than 1% of intracranial tumors, of which only 7% have a cystic component. We documented 2 cases of males with cystic trigeminal Schwannomas, their symptoms, the diagnosis process and the imaging characteristics. In addition, a review of the literature is performed, with emphasis on the radiological classification of this rare entity, that constitutes a diagnostic challenge for the radiologist, who has an essential role in the approach to the disease and therefore in its management.

Gamma knife radiosurgery for trigeminal schwannoma: a 20-year experience with long-term treatment outcome

PURPOSE

This study evaluated the long-term tumor control rate (TCR) and symptomatic outcomes of patients treated with gamma knife radiosurgery (GKRS) for trigeminal schwannomas (TSs).

METHODS

Thirty-two patients with TS who underwent GKRS between January 1994 and January 2013 with at least 2 years of follow-up were enrolled in the study. Clinical charts and surgical records were retrospectively reviewed to evaluate factors affecting TCR and symptomatic outcomes. The median patient age was 57.5 years (max = 81, interquartile range [IQR] = 51-67), and the median tumor volume was 3.55 cm³ (max = 25.2 cm³, IQR = 2.0-6.2 cm³). The median marginal and maximum doses were 13.0 Gy (max = 18.0 Gy, IQR = 12.5-15 Gy) and 23.8 Gy (max = 35 Gy, IQR = 21.7-25.0 Gy), respectively.

RESULTS

At a median follow-up of 90.5 months (max = 281 months, IQR = 49-139.75 months), the actuarial 3-, 5-, and 10-year TCR were 93.8, 86.2, and 80.8%, respectively. Our data and multivariate analysis indicated that the target volume was the only significant factor determining TCR and that larger tumors (> 5 cm³) were more likely to progress (p = 0.011). Cystic tumors had a higher incidence of transient enlargement and temporary symptom change compared to those in solid tumors. An unfavorable outcome of symptoms was observed in five patients (15.6%). Complications were observed in two patients (6.25%), including hydrocephalus and radio-induced trigeminal neuropathy, respectively.

CONCLUSIONS

GKRS can be a safe and effective treatment modality for TS with long-term follow-up, especially for small tumors. An extended period of follow-up observation is required to conclude the clinical response to GKRS.

Natural History, Multimodal Management, and Quality of Life Outcomes of Trigeminal Schwannomas

Background  Trigeminal schwannomas are the second most common among intracranial schwannomas. These can arise from anywhere between the root and the distal extracranial branches of the trigeminal nerve. Clinical presentation depends on location and size, including but not limited to facial hypesthesia or pain, headaches, dizziness, ataxia, and diplopia. Literature is strikingly scant discussing the natural history of these lesions, while the treatment goals are heavily dependent on tumor presentation. Management decisions must be individualized to each tumor and each patient, while attempting to maximize the quality of life. We present the natural history of these lesions as well as their management by surgical resection or radiation therapy, and report long-term quality of life outcomes. Methods  Between 2001 and 2015, 24 patients (66.7% female) with trigeminal schwannomas were diagnosed and managed at Vancouver General Hospital. We analyzed the clinical presentation, surgical results, resection rates, patient quality of life, and complications. To complete the evaluation, we prospectively collected 36-Item Short Form Health Survey (SF-36) quality of life assessments for comparison. Results  We identified 12 patients treated with a craniotomy and surgical resection, 4 were treated with radiation therapy, while 8 patients were followed by observation. Mean age of study cohort was 49.2 years (range, 23-79 years), and most patients presented with facial hypesthesia (54.2%) and headaches (37.5%), while 37.5% were incidental findings. There were no major differences in patient demographics between the three groups. Patients offered surgery had larger lesions (mean diameter, 3.4 ± 1.1 cm) when compared with those that were irradiated or observed, and were more likely to have extracranial extension. Overall patient quality of life improved following treatment (ΔSF-36 + 12.9) at 3.9 years. Conclusions  The treatment goals of trigeminal schwannomas focus on improvement in neurologic symptoms, relief of mass effect, and preservation of cranial nerve function. We demonstrate that smaller lesions found incidentally with minimal symptoms can be followed safely with serial imaging, with 1 of 9 (11.1%) progressing to require treatment over the course of 7.1 years. Management of trigeminal schwannomas should be individualized with an involvement of a multidisciplinary skull base team.

Endoscopic endonasal approach for trigeminal schwannomas: our experience of 39 patients in 10 years

BACKGROUND

The anatomical locations involved in trigeminal schwannomas (TSs) are quite complex. The endoscopic endonasal approach provides a minimal damage access corridor to both anterior and middle skull base for surgery. Given the nerve function recovery and postoperative neurological deterioration varied in different reports, the author demonstrates his surgery tips and the functional outcomes under endoscopic surgery in one single institution.

METHODS

A retrospective review of patients with TSs was undertaken to assess the outcome of endoscopic surgery from 2006 to 2016. Clinical features, imaging findings, preoperative/postoperative neurological deficits, surgical approaches and followed up data were collected.

RESULTS

Thirty-nine patients with TSs were included in this study. Surgical approaches include endoscopic medial maxillectomy approach (n = 8), endoscopic endonasal-assisted sublabial transmaxillary approach (n = 27) and endoscopic endonasal-assisted sublabial transmaxillary combined with septectomy (n = 4). Gross total resection and sub-total resection were achieved in 27 and 10 patients, respectively. The most common chief complaint was facial numbness, accounting for 41%, with a resolved rate of 62.5% after treatment. Fifteen patients developed new neurologic symptoms, including facial numbness/pain (n = 9 and 2, respectively), dry eye (n = 3) and mastication weakness (n = 1). Eight of these patients had partial improvement except for patients with dry eye.

CONCLUSION

Endoscopic endonasal approach represents a safe and effective surgical procedure for TSs in pterygopalatine fossa, infratemporal fossa and even Meckel cave. Tumor resection can be achieved by endoscope with few neurologic deficits and complications.

Solid cystic trigeminal schwannoma with intraorbital extension causing proptosis and vision loss

Schwannomas are slowly growing, well capsulated, benign tumors. Involvement of vestibular nerve is most commonly followed by trigeminal nerve. Trigeminal schwannoma is rare entity, and cystic degeneration with intraorbital extension of trigeminal schwannoma is even rarer. These tumors occur in fourth and fifth decades of life and patients have variable presentation depending on which cranial compartment is involved. Orbital schwannoma usually presents with proptosis with or without vision loss. We are reporting such a rare case of solid cystic trigeminal schwannoma with intraorbital extension through superior orbital fissure that was removed surgically.

Radiosurgery for Secondary Trigeminal Neuralgia: Revisiting the Treatment Paradigm

BACKGROUND

The mechanisms by which surgery and radiation elicit pain relief in trigeminal neuralgia (TN) secondary to mass lesions vary widely. We aimed to evaluate the outcomes of radiation to the nerve rather than to the lesion in the treatment of secondary TN.

METHODS

We retrospectively reviewed all patients who underwent radiation at the University of California, Los Angeles for TN secondary to tumors. The Barrow Neurological Institute (BNI) pain score was used to evaluate pain outcomes.

RESULTS

Twelve patients were identified; 4 were male and 8 were female. Their mean age at treatment was 59.8 years (range, 47.7-84.7 years). Tumor pathologies included meningioma (n = 8), squamous cell carcinoma (n = 2), vestibular schwannoma (n = 1), and hemangiopericytoma (n = 1). No patient suffered from multiple sclerosis. Ten patients underwent initial radiation targeting their tumors-radiosurgery in 3 and fractionated radiation therapy in 7 others. Only 6 among these 10 experienced at least partial relief, which lasted a mean 6 months. Radiosurgery targeting the trigeminal nerve was eventually performed. Overall, 10 of 12 (83.3%) patients experienced good initial pain relief, complete in 6 (50%) patients. Pain recurred in 6 (60%) patients, at a mean 41 months after radiosurgery to the trigeminal nerve. Three patients experienced facial sensory dysfunction postprocedurally at a mean follow-up duration of 57 months.

CONCLUSION

In contrast to tumor radiation, radiosurgery to the trigeminal nerve root resulted in reasonable and longer pain reduction, on par with the literature regarding surgical resection, with low risk of additional complications.

Lateral orbitotomy for a maxillary nerve schwannoma: case report

Authors of this report describe a Fukushima Type D(b) or Kawase Type ME2 trigeminal schwannoma involving the right maxillary division in a 59-year-old woman who presented with intermittent right-sided facial numbness and pain. This tumor was successfully resected via a right lateral orbitotomy without the need for craniotomy. This novel approach to a lesion of this type has not yet been described in the scientific literature. The outcome in this case was good, and the patient's intra- and postoperative courses proceeded without complication. The epidemiology of trigeminal schwannomas and some technical aspects of lateral orbitotomy, including potential advantages of this approach over traditional transcranial as well as fully endoscopic dissections in appropriately selected cases, are also briefly discussed.

Multimodality Management of Trigeminal Schwannomas

Patients presenting with trigeminal schwannomas require multimodality management by a skull base surgical team that can offer expertise in both transcranial and transnasal approaches as well as radiosurgical and microsurgical strategies. Improvement in neurologic symptoms, preservation of cranial nerve function, and control of mass effect are the primary goals of management for trigeminal schwannomas. Complete surgical resection is the treatment of choice but may not be possible in all cases. Radiosurgery is an option as primary management for small- to moderate-sized tumors and can be used for postoperative residuals or recurrences. Planned surgical resection followed by SRS for residual tumor is an effective option for larger trigeminal schwannomas. The endoscopic resection is an excellent approach for patients with an extradural tumor or tumors isolated to the Meckel cave. A detailed analysis of a tumor and its surroundings based on high-quality imaging can help better estimate the expected outcome from each treatment. An expert skull base team should be able to provide precise counseling for each patient's situation for selecting the best option.

Denervation of the Eustachian Tube and Hearing Loss Following Trigeminal Schwannoma Resection

Objectives To discuss eustachian tube dysfunction (ETD) as a cause of hearing loss and to discuss its pathogenesis following resection of trigeminal schwannomas.

Methods Presented herein are two cases of trigeminal schwannoma that were resected surgically with sacrifice of the motor branch of the trigeminal nerve. Neither of the cases had evidence of extracranial extension nor preoperative ETD. Both patients developed ETD and have been followed without evidence of schwannoma recurrence.

Conclusions Trigeminal schwannomas are rare tumors that typically require surgical resection. Hearing loss is a potential postsurgical deficit and warrants evaluation by an otolaryngologist with consideration given to a preoperative audiogram. ETD as a result of trigeminal motor branch sacrifice should be included in the differential diagnosis of postoperative hearing loss in this patient subset as it may be reversed with placement of a tympanostomy tube.

Identification of cranial nerves around trigeminal schwannomas using diffusion tensor tractography: a technical note and report of 3 cases

BACKGROUND

There are no large series studies identifying the locations of cranial nerves (CNs) around trigeminal schwannomas (TSs); however, surgically induced cranial neuropathies are commonly observed after surgeries to remove TSs. In this study, we preoperatively identified the location of CNs near TSs using diffusion tensor tractography (DTT).

METHODS

An observational study of the DTT results and intraoperative findings was performed. We preoperatively completed tractography from images of patients with TSs who received surgical therapy. The result was later validated during tumorectomy.

RESULTS

A total of three consecutive patients were involved in this study. The locations of CNs V-VIII in relation to the tumor was clearly revealed in all cases, except for CN VI in case 3.The predicted fiber tracts were in agreement with intraoperative observations.

CONCLUSIONS

In this study, preoperative DTT accurately predicted the location of the majority of the nerves of interest. This technique can be applied by surgeons to preoperatively visualize nerve arrangements.

Intracranial trigeminal schwannoma

Intracranial trigeminal schwannomas are rare tumors. Patients usually present with symptoms of trigeminal nerve dysfunction, the most common symptom being facial pain. MRI is the imaging modality of choice and is usually diagnostic in the appropriate clinical setting. The thin T2-weighted CISS 3D axial sequence is important for proper assessment of the cisternal segment of the nerve. They are usually hypointense on T1, hyperintense on T2 with avid enhancement post gadolinium. CT scan is supplementary to MRI, particularly for tumors located in the skull base. Imaging plays a role in diagnosis and surgical planning. In this pictorial essay, we retrospectively reviewed imaging findings in nine patients with pathologically proven trigeminal schwannoma. Familiarity with the imaging findings of intracranial trigeminal schwannoma may help to diagnose this entity.

Frontotemporal epi- and subdural approach to a cavernous sinus tumor for sphenobasal vein preservation--technical case report

In cavernous sinus (CS) surgery, venous complication may occur in some types of venous drainage. The sphenobasal vein (SBV) drains from the superficial middle cerebral vein (SMCV) to the pterygoid venous plexus at the temporal skull base. A frontotemporal epi- and interdural approach (Dolenc approach), which is one of the CS approaches, may damage the SBV's route. We report a case of intracavernous trigeminal schwannoma that contained the SBV and discuss our modified surgical procedure that combined epi- and subdural approaches to preserve the SBV. A 64-year-old man complained of right progressive oculomotor palsy and was referred to our hospital for surgery. MR images revealed a hemorrhagic tumor in the right CS. Three-dimensional venography revealed that the SMCV drained into the pterygoid venous plexus via the SBV. After identifying the first branch of the trigeminal nerve epidurally, we incised the dura linearly along the sylvian fissure and entered the subdural space to visualize the SBV. The incision was continued to the meningeal dura of the lateral wall of the CS along the superior margin of the first branch of the trigeminal nerve, and the Parkinson's triangle was opened from the subdural side. The tumor was grossly totally removed, and the SBV was preserved. In conclusion, a frontotemporal epi- and subdural approach to the intracavernous trigeminal schwannoma can effectively preserve the SBV.

Nuances in the treatment of malignant tumors of the clival and petroclival region

Introduction Malignancies of the clivus and petroclival region are mainly chordomas and chondrosarcomas. Although a spectrum of malignancies may present in this area, a finite group of commonly encountered malignant pathologies will be the focus of this review, as they are recognized to be formidable pathologies due to adjacent critical neurovascular structures and challenging surgical approaches.

Objectives The objective is to review the literature regarding medical and surgical management of malignant tumors of the clival and petroclival region with a focus on clinical presentation, diagnostic identification, and associated adjuvant therapies. We will also discuss our current treatment paradigm using endoscopic, open, and combined approaches to the skull base.

Data Synthesis A literature review was conducted, searching for basic science and clinical evidence from PubMed, Medline, and the Cochrane Database. The selection criteria encompassed original articles including data from both basic science and clinical literature, case series, case reports, and review articles on the etiology, diagnosis, treatment, and management of skull base malignancies in the clival and petroclival region.

Conclusions The management of petroclival malignancies requires a multidisciplinary team to deliver the most complete surgical resection, with minimal morbidity, followed by appropriate adjuvant therapy. We advocate the combination of endoscopic and open approaches (traditional or minimally invasive) as required by the particular tumor followed by radiation therapy to optimize oncologic outcomes.

A Rare Finding of Schwannoma of the Vidian Canal: A Case Report

Background Schwannomas of the vidian canal are an extremely rare type of intracranial tumor that can have variable clinical presentations including headache, facial pain, facial muscle paralysis, decreased lacrimation, or nasal dryness. We present an atypical case of an incidentally identified asymptomatic vidian canal schwannoma.

Case Description A 49-year-old woman with a history of multiple sclerosis presented for routine surveillance magnetic resonance imaging that detected an ovoid mass originating in the vidian canal. Given the unusual location of the lesion, an endoscopic endonasal biopsy was performed and confirmed the diagnosis of a vidian canal schwannoma, for which the patient chose to receive fractionated radiation therapy.

Conclusion When a vidian canal tumor is identified, endoscopic endonasal biopsy can be used to confirm the diagnosis before pursuing either surgical or radiotherapy treatment. In particular, fractionated radiation therapy offers a radiobiologically safe means of delivering radiation when there is concern for late radiation-related side effects following treatment completion.

A suggestion of modified classification of trigeminal schwannomas according to location, shape, and extension

Background

Comprehensive knowledge of the anatomical features of trigeminal schwannomas (TSs) is essential in planning surgery to achieve complete tumor resection. In the current report, we propose a modified classification of TSs according to their location of origin, shape, and extension into the adjacent compartment, and discuss appropriate surgical strategies with this classification.

Methods

We retrospectively analyzed 49 patients with TS who were treated surgically by a single neurosurgeon at the Asan Medical Center between 1993 and 2013.

Results

There were 22 males and 27 females, with the median age of 40 years (range, 21-75 years). Median tumor size was 4.0 cm in diameter (2.0-7.0 cm). Tumors were classified as follows: Type M (confined to the middle fossa; 8 cases, 19.0%), P (confined to the posterior fossa; 2 cases, 4.8%), MP (involving equally both middle and posterior fossae; 5 cases, 11.9%), Mp (predominantly middle fossa with posterior fossa extension; 6 cases, 14.3%), Pm (predominantly posterior fossa with middle fossa extension; 16 cases, 38.1%), Me (predominantly middle fossa with extracranial extension; 4 cases, 9.5%). Surgical approach was chosen depending on the tumor classification. More specifically, a frontotemporal craniotomy and extradural approach with or without zygomatic or orbitozygomatic osteotomy was applied to M- or Mp-type tumors; a lateral suboccipital craniotomy with or without suprameatal approach was applied to the majority of P- or Pm-type tumors; and a posterior transpetrosal approach was used in four tumors (three Pm and one MP). Gross total resection was achieved in 95.9% of patients, and the overall recurrence rate was 4.1% (2 patients). Postoperatively, trigeminal symptoms were improved or unchanged in 51.0% of cases (25 patients). Surgical complications included meningitis (5 patients) and cerebrospinal fluid leakage (3 patients). There was no mortality.

Conclusion

TSs are well to be classified with our modified classification and able to be removed effectively and safely by selecting appropriate surgical approaches.

Endoscope-Assisted Retrosigmoid Intradural Suprameatal Approach for Surgical Treatment of Trigeminal Schwannomas

BACKGROUND:

Trigeminal schwannomas are the most common intracranial nonvestibular schwannomas, and the dumbbell-shaped subtype is the most challenging.

OBJECTIVE:

To evaluate the efficiency and safety of the endoscope-assisted retrosigmoid intradural suprameatal approach (EA-RISA) for dumbbell trigeminal schwannomas and to compare EA-RISA with classic RISA.

METHODS:

A retrospective study of all patients with trigeminal schwannomas was performed with a focus on dumbbell tumors. Tumors were classified according to a modified Samii classification. Extent of tumor removal, outcome, and morbidity rates in the 2 subgroups were compared.

RESULTS:

Twenty patients were enrolled: 8 had dumbbell-shaped tumors (type C1), 8 had middle fossa tumors (A1-3), 3 had extracranial extension (D2), and 1 had posterior fossa tumor. Gross total resection was achieved in 15 and near-total resection in 5 patients. In 4 patients with dumbbell tumors, the classic RISA (Samii approach) was used; EA-RISA was used in the other 4 patients. The extent of petrous apex drilling was determined individually on the basis of the anatomic variability of suprameatal tubercle and degree of tumor-induced petrous apex erosion; in 2 patients, only minimal drilling was needed. The endoscope was applied after microsurgical tumor removal and in 3 of 4 patients revealed a significant unrecognized tumor remnant in the anterolateral and superolateral aspects of the Meckel cave. Thus, the EA-RISA technique allowed gross total resection of the tumor.

CONCLUSION:

The EA-RISA enlarges the exposure obtained with the classic RISA. Its judicious use can help achieve safe and radical removal of dumbbell-shaped trigeminal schwannomas (C1 type).

Operative management of trigeminal neuromas: an analysis of a surgical experience with 55 cases

BACKGROUND

The trigeminal schwannoma is the second most common intracranial schwannoma. Their proximity to the critical skull base neural and vascular structures increases the complexity of surgical treatment. The aim of this study was to better understand the surgical approaches and the prognosis, as well as to assess the optimum therapeutic schedule.

METHODS

This was a retrospective study of 55 patients with trigeminal schwannomas who visited our department between Jan 2007 and Jan 2012. We analyzed the clinical and radiological presentation, tumor characteristics, surgical approaches, the prognosis.

RESULTS

The patients were 30 women and 25 men of mean age 36 years (range, 6-66 years) who received postoperative neurological and neuroradiological follow-up. The tumor was located in the middle fossa (type A) in 13 cases, in the posterior fossa (type B) in ten cases, in the middle and posterior fossae (type C) in 21 cases, and in the branches of the trigeminal nerve (type D) in 11 cases. The most common symptom was facial hypesthesia or numbness in 36 patients (65 %) . Total and nearly total tumor resection was achieved in 51 cases (93 %). Three patients (5 %) had worsening of preexisting deficits and there was no perioperative mortality. With an average follow-up period of 35 months, facial hypesthesia persisted in 26 patients (72 %),and improved in ten patients (28 %). Facial pain was relieved in 11 patients (100 %). There has been a recurrence in one case (2 %) and all patients resumed independent and social reintegration.

CONCLUSION

This study demonstrates radical surgery with excellent neurological outcomes is the primary treatment of trigeminal schwannomas. Appropriate selection of surgical approach according to tumor types is highly important and necessary. The preoperative facial pain could be relieved, hypesthesia frequently remains or could even be worsened after surgery.

Long-term results for trigeminal schwannomas treated with gamma knife surgery

PURPOSE

Surgical resection is considered the desirable curative treatment for trigeminal schwannomas. However, complete resection without any complications remains challenging. During the last several decades, stereotactic radiosurgery (SRS) has emerged as a minimally invasive treatment modality. Information regarding long-term outcomes of SRS for patients harboring trigeminal schwannomas is limited because of the rarity of this tumor. The aim of this study was to evaluate long-term tumor control and functional outcomes in patients harboring trigeminal schwannomas treated with SRS, specifically with gamma knife surgery (GKS).

METHODS AND MATERIALS

Fifty-three patients harboring trigeminal schwannomas treated with GKS were evaluated. Of these, 2 patients (4%) had partial irradiation of the tumor, and 34 patients (64%) underwent GKS as the initial treatment. The median tumor volume was 6.0 cm(3). The median maximum and marginal doses were 28 Gy and 14 Gy, respectively.

RESULTS

The median follow-up period was 98 months. On the last follow-up image, 7 patients (13%) had tumor enlargement, including the 2 patients who had partial treatment. Excluding the 2 patients who had partial treatment, the actuarial 5- and 10-year progression-free survival (PFS) rates were 90% and 82%, respectively. Patients with tumors compressing the brainstem with deviation of the fourth ventricle had significantly lower PFS rates. If those patients with tumors compressing the brainstem with deviation of the fourth ventricle are excluded, the actuarial 5- and 10-year PFS rates increased to 95% and 90%, respectively. Ten percent of patients had worsened facial numbness or pain in spite of no tumor progression, indicating adverse radiation effect.

CONCLUSIONS

GKS can be an acceptable alternative to surgical resection in patients with trigeminal schwannomas. However, large tumors that compress the brainstem with deviation of the fourth ventricle should be surgically removed first and then treated with GKS when necessary.

Intra-parotid facial nerve schwannoma with intra-temporal extension; a case report. Is there a role for stereotactic radiotherapy?

Facial nerve schwannoma (FNS) is an extremely rare benign tumour that may arise anywhere along the course of the facial nerve; the standard treatment is total removal via microsurgery. Stereotactic radiotherapy has been shown to be effective in the treatment of skull base tumours, in particular for acoustic neuromas; it is interesting to notice that also the few data existing in literature about the use of radiotherapy for non acoustic schwannomas show an excellent local control rate and few adverse effects. Here we report a case of facial nerve neuroma, involving the nerve sheath from the geniculate ganglion to the parotid gland, treated with fractionated stereotactic radiotherapy after debulking surgery.

Large trigeminal schwannoma of the infratemporal fossa: evaluation of neoangiogenesis in this rare neoplasm

BACKGROUND

Trigeminal schwannomas are uncommon intracranial tumors. Extracranial trigeminal schwannomas in the infratemporal fossa are rare.

METHODS

We present a case with a clinical history of facial pain. MRI and CT scans showed a mass arising from the infratemporal fossa extending into the intracranial space.

RESULTS

We performed a combined neurosurgical and maxillofacial approach with preoperative endovascular embolization. Complete removal of the parasellar component was achieved with a minimal extracranial neoplastic residual. High microvessel density, reflecting intense neoangiogenesis, was detected through the immunohistochemical staining with endoglin.

CONCLUSIONS

Due to the unique development pattern of trigeminal schwannoma involving multiple intracranial fossae and extracranial compartment, we chose a combined neurosurgical and maxillofacial approach with preoperative embolization of the tumor. Immunohistochemical findings suggest that the extensive growth observed may be related to an intense neoangiogenesis, opening the perspective to novel therapeutic options based on the inhibition of neoangiogenesis.

Stereotactic radiosurgery for trigeminal schwannomas

PURPOSE

Traditionally trigeminal schwannomas (TS) have been treated microsurgically; however, this is often associated with significant morbidity, and complete excision remains a challenge. Stereotactic radiosurgery (SRS) offers a minimally invasive alternative in treating TS. We report on our cumulative experience of using SRS in the treatment of TS.

MATERIALS AND METHODS

Seventy-four TS patients (four with NF2) were treated with SRS using the Leksell Gamma Knife. Mean age (±1 SD) at treatment was 47.1 (15.5) years with a mean interval between presentation and treatment of 30.9 months. Thirty (40.5%) patients had undergone previous surgery on average 47.3 months prior to SRS. The average target volume was 5.3 cm(3) (range 0.4-19.9 cm(3)) and was treated with a mean prescription dose of 16.4 (3.9) Gy to the tumour margin.

RESULTS

Average follow-up was 48.2 months (range 6-168 months). Tumour size remained static in 58 (78.4%) patients and showed radiological evidence of shrinkage in 11 (14.9%). Tumour progression occurred in five (6.6%) patients on average 40 months after SRS (range 12-108). Progression-free survival (PFS) for all patients was 98.5% at 1 year, 92.7% at 5 years and 79.4% at 10 years. Log-rank analysis indicated a significantly worse outcome for NF2 patients (p = 0.001) who demonstrated a PFS of 100% at 1 year and 50% at 5 years. Seven patients developed adverse radiation effects whilst improvements in pre-treatment cranial nerve dysfunction were achieved in eight patients.

CONCLUSIONS

SRS is an effective treatment option in patients with residual or newly diagnosed TS. In view of the results of this study we would advocate a more front-line role for the Gamma Knife in the treatment of this tumour group.

Schwannoma of extraocular nerves: survey of literature and case report of an isolated third nerve schwannoma

An unusual case of schwannoma arising from the third cranial nerve in a thirteen year old male is reported. The patient presented with paresis of the right oculomotor nerve and ipsilateral hemiparesis. The clinical features of this case are discussed and the pertinent medical literature reviewed.

A cranio-orbital-zygomatic approach to dumbbell-shaped trigeminal neurinomas using the petrous window

We applied a cranio-orbital-zygomatic approach that extends the temporal craniotomy more posteriorly and minimizes the frontal orbitotomy of an ordinary orbitozygomatic approach in order to provide wide access to the already eroded petrous apices along the long axis of trigeminal neurinomas. We treated seven dumbbell-shaped trigeminal neurinomas between 1991 and 1998 (mean follow-up, 38 months; range, 9 to 109 months). The configuration of the tumor mass was assessed on magnetic resonance imaging by measuring its long diameter in the middle and posterior fossae and the width of petrous erosion. Tumors were then classified into five types based on their distribution over the petrous ridge. Total removal was achieved in six patients, who showed no evidence of tumor recurrence during the follow-up period. The only major complication was one case of anesthesia dolorosa. The one patient with a subtotal removal developed a recurrence 12 months after surgery, in the posterior fossa. The cranioorbital-zygomatic approach could be an effective method for removing dumbbell-shaped trigeminal neurinomas, particularly in cases of wide petrous erosion from the tumor. If, however, the tumor has a larger posterior fossa component, this approach may not provide adequate exposure to achieve a total resection.