Trigeminal neuroma: analysis of surgical experience with 73 cases

Interdural extra-arachnoidal resection of fifth nerve schwannomas with tailored petrous drilling: Eliminating the blind spot

BACKGROUND AND OBJECTIVES

Around 20-40% of trigeminal schwannomas (TS) are dumbbell shaped, spanning the middle and posterior cranial fossa The petrous apex is often truncated in these patients, aiding surgical resection of both compartments through the middle fossa approach. However, a less eroded petrous creates a blind spot, making total resection difficult. This study describes the feasibility of an approach combining expanded Meckel cave access with tailored petrous bone drilling to optimize tumor visualization and resection.

METHODS

Eleven patients with dumbbell TS and minimal petrous apex erosion underwent the described surgery. Surgical steps included temporo-orbito-zygomatic craniotomy, middle fossa floor drilling, navigation aided (tailored) extradural petrous bone drilling and extra-arachnoidal tumor excision. Extent of resection and postoperative outcomes were recorded.

RESULTS

Patients presented with trigeminal nerve dysfunction (n = 9; sensory -9 and motor - 5), headache(8/11), ataxia (7/11) and pseudobulbar palsy (3/11). Complete tumor resection was achieved in all patients. Postoperatively, 8 out of 9 patients had transient increase in facial hypoesthesia with conjunctival injection in 3. It improved within 3-6 months, except in four cases wherein mild hypoesthesia persisted. Motor symptoms improved in 2 of 5 patients. Two developed transient 6th nerve paresis, that resolved in 2 months. Cerebellar and brainstem pressure symptoms resolved in all. No patients developed new onset permanent neurological deficit. Two patients reported mild post-craniotomy masticatory difficulty.

CONCLUSIONS

The additional tailored petrous bony drilling enhances the surgeon's view, allowing a higher chance of total resection with no major operative morbidity.

A, Rao KVLN, Somanna S. Surgical Management of Large (≥3 cm) Trigeminal Schwannomas: Functional Outcomes and Approach Selection in Multicompartmental Schwannomas

Introduction  Trigeminal schwannoma surgery has shown a remarkable improvement in functional recovery and tumor resection. In the era of radiosurgery, these outcomes need to be characterized for tumors which are outside the realm of being treated with radiosurgery. We present a series of trigeminal schwannomas larger than 3 cm, surgical approaches used, and outcomes with an emphasis on functional recovery in a high-volume center with radiosurgery facilities. Method  All consecutive cases of trigeminal schwannoma from January 2012 to May 2021 which were more than 3 cm in size and underwent microsurgery were included in this series. The surgical approach, neurological outcomes, and extent of resection were defined objectively with pre/postoperative magnetic resonance imaging. Results  A total of 83 such cases (>3 cm) were found, with cranial nerve symptoms (5th most common) being the commonest. Twenty three percent cases had blindness due to secondary optic atrophy and eighteen percent had long tract motor symptoms signifying the tumor burden in our series. Radiological gross total excision was achieved in 75.9% cases. Conclusion  Large-volume schwannomas present with cranial nerve involvement and may need extensive skull base approaches. Functional outcomes need to be prioritized and can be achieved albeit with lesser gross resection rates. Hearing and facial preservation in addition to relief of trigeminal symptoms should be the goal of resection with minimal additional morbidity.

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.

Operative management of trigeminal schwannomas: based on a modified classification in a study of 93 cases

BACKGROUND

Advances in microscopic and endoscopic surgical techniques have outpaced traditional classification and transcranial surgical strategies, especially with reference to the treatment of trigeminal schwannomas (TSs). A modified TS classification is proposed and appropriate surgical strategies are discussed.

METHODS

The cases of 93 patients who underwent surgical treatment in Beijing Tiantan Hospital in the previous 6 years were analyzed retrospectively, and a literature review was conducted.

RESULTS

Classification is based on surgical direction. Tumors were classified as follows: type A, backward orientation, located in the orbit or orbit and middle cranial fossa (8 cases, 8.6%); type B, upward orientation, located in the pterygopalatine fossa, infratemporal fossa or pterygopalatine fossa, infratemporal fossa, and middle cranial fossa (23 cases, 24.7%); type C, forward and backward orientations, located in the middle cranial fossa, posterior cranial fossa or both (58 cases, 62.4%); and type D, located in multiple regions (4 cases, 4.3%). 91.40% of patients underwent gross total resection (GTR) with 29 cases receiving endoscopic resection of whom 93.10% (27/29) experienced GTR.

CONCLUSION

The 93 cases were satisfactorily divided into four types, according to tumor location and surgical orientation, enabling safe and effective removal by appropriate surgery.

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.

Endoscopic Endonasal Approach for Trigeminal Schwannomas: Tailored Approaches Based on Lesion Traits

OBJECTIVES

To describe four endoscopic endonasal subapproaches, namely, the trans-lamina papyracea, trans-prelacrimal recess, trans-Meckel's cave, and transclival approaches for trigeminal schwannomas (TSs).

METHODS

This retrospective study reviewed the medical records and intraoperative videos of 38 patients with TSs who underwent endoscopic endonasal approach (EEA) between Jan 2013 and Dec 2021.

RESULTS

According to Jeong's classification, for TS equally in middle and posterior fossae (MP), a purely trans-Meckel's cave approach was carried out in 2 cases, and a combined transclival approach was carried out in 4 cases. The four tumors that involved infratemporal fossa (two E3, one mE3, and one Mpe3) were performed via a trans-prelacrimal recess approach, and type Mpe3 was also assisted by the trans-Meckel's cave approach. One patient with type E1 was treated with a trans-lamina papyracea approach. The other 27 cases, including type M, Mp, ME2, and MpE2, were all removed by a purely trans-Meckel's cave approach. Thirty-six patients (97.4%) received total resection under a purely EEA. The functional abilities and preoperative symptoms of 31 patients (88.6%) improved. Eight (21.1%) patients experienced permanent neurological function deficits. Postoperative cerebrospinal fluid and intraoperative internal carotid artery injury occurred in 1 (2.6%) patient.

CONCLUSION

According to the specific endoscopic endonasal subapproaches corresponding to the different TS locations, satisfactory results can be obtained for most types of tumors. It represents an effective alternative to the open transcranial approach and can also be properly used in most types of TS with experienced hands.

LEVEL OF EVIDENCE

4 Laryngoscope, 133:2564-2571, 2023.

Endoscopic far-lateral supracerebellar infratentorial approach for resection of dumbbell-shaped trigeminal schwannoma: surgical techniques and preliminary results

BACKGROUND

Trigeminal schwannomas (TSs) are mostly benign tumors. However, dumbbell-shaped TSs are most challenging for surgeons and pose a high surgical risk.

OBJECTIVE

We describe the technique of the purely endoscopic far-lateral supracerebellar infratentorial approach (EFL-SCITA) for removing dumbbell-shaped TSs and further discuss the feasibility of this approach and our experience.

METHODS

EFL-SCITA was performed for resection of 5 TSs between January 2020 and March 2023. The entire procedure was performed endoscopically with the goal of total tumor resection. During the operation, the tumor was exposed in close proximity and multiple angles under the endoscope, and the peri-tumor nerves were carefully identified and protected, especially the normal trigeminal fiber bundles around the tumor.

RESULTS

All the tumors of 5 patients involved the middle and posterior cranial fossa, of which total removal was achieved in 2 patients and near-total removal in 3 patients. The most common preoperative symptoms were relieved after surgery. Two patients had postoperative mild facial paralysis (House-Brackmann grade II), and 1 patient had abducens palsy; both recovered during the follow-up period. Two patients experienced new postoperative facial hypesthesia, and 1 experienced mastication weakness, which did not recover. There was no tumor recurrence or residual tumor growth during the follow-up period in any of the patients.

CONCLUSION

EFL-SCITA is a new and effective alternative for the surgical treatment of TSs. For dumbbell-shaped TSs, this approach provides sufficient surgical field exposure and freedom of operation.

Trigeminal Schwannoma: A Retrospective Analysis of Endoscopic Endonasal Management, Treatment Outcomes, and Neuropathic Sequelae

Introduction  Trigeminal schwannomas (TS) are rare skull base tumors that have been associated with significant neuropathic sequalae for patients. The authors aim to evaluate the clinical features, treatment outcomes, and neuropathic sequelae following endoscopic endonasal approach (EEA) for TS. Methods  The study involves a retrospective review of patients who underwent EEA for resection of TS at a single academic institution between 2004 and 2020. Radiographic and clinical data were recorded and analyzed. Results  A total of 16 patients were abstracted, with a mean age at the time of surgery of 44 years with a slight female (1.83:1) predominance. Primary preoperative symptomatology included facial pain/neuralgia ( n  = 5, 31.3%), facial hypoesthesia ( n  = 4, 25.0%), and headache ( n  = 4, 25.0%). Following TS resection, patients were found to have facial hypoesthesia ( n  = 11, 68.8%), neuropathic keratopathy ( n  = 4, 25.0%), and mastication musculature atrophy ( n  = 3, 18.8%). Patients with preoperative facial pain/neuralgia ( n  = 5, 31.3%) were significantly more likely to try adjunctive pain therapies ( p  = 0.018) as well as seek pain consultation ( p  = 0.018). Patients with preoperative migraines ( n  = 2, 12.5%) were significantly more likely to trial adjunctive pain therapies ( p  = 0.025) and undergo evaluation with pain specialists ( p  = 0.025). Finally, patients with preoperative pharmacologic agent utilization were significantly more likely to trial adjunctive pain therapies ( p  = 0.036) and pursue pain consultation ( p  = 0.036). Conclusion  Some degree of trigeminal dysfunction may be more common than previously reported following EEA for TS resection. Factors that appear to play a role in the development of trigeminal dysfunction include pre-existing pain syndromes such as facial pain/neuralgia or headache and preoperative medication utilization.

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.

Variants of the Anterior Subtemporal Approach to the Gasserian Ganglion and Related Structures: An Anatomical Study With Relevant Implications for Keyhole Surgery

BACKGROUND

The advantages and limitations of different craniotomy positions and approach trajectories to the gasserian ganglion (GG) and related structures using an anterior subtemporal approach have not been studied systematically. Knowledge of these features is of importance when planning keyhole anterior subtemporal (kAST) approaches to the GG to optimize access and minimize risks.

METHODS

Eight formalin-fixed heads were used bilaterally to assess temporal lobe retraction (TLR), trigeminal exposure, and relevant anatomical aspects of extra- and transdural classic anterior subtemporal (CLAST) approaches compared with slightly dorsally and ventrally allocated corridors.

RESULTS

TLR to the GG and foramen ovale was found to be lower via the CLAST approach (P < 0.001). Using the ventral variant, TLR to access the foramen rotundum was minimized (P < 0.001). The overall TLR was maximal using the dorsal variant (P < 0.001) owing to interposition of the arcuate eminence. An extradural CLAST approach required wide exposure of the greater petrosal nerve (GPN) and middle meningeal artery (MMA) sacrifice. Both maneuvers were spared using a transdural approach. Using CLAST, medial dissection >39 mm can enter the Parkinson triangle, jeopardizing the intracavernous internal carotid artery. The ventral variant enabled access to the anterior portion of the GG and foramen ovale without the need for MMA sacrifice or GPN dissection.

CONCLUSIONS

The CLAST approach provides high versatility to approach the trigeminal plexus, minimizing TLR. However, an extradural approach jeopardizes the GPN and requires MMA sacrifice. The risk of cavernous sinus violation exists when progressing medially beyond 4 cm. The ventral variant has some advantages to access the ventral structures and avoid MMA and GPN manipulation. In contrast, the usefulness of the dorsal variant is rather limited owing to the greater TLR required.

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.

Schwannomas of Brain and Spinal Cord

Schwannomas are benign tumors originating from the Schwann cells of cranial or spinal nerves. The most common cranial schwannomas originate from the eight cranial nervevestibular schwannomas (VS). VS account for 6-8% of all intracranial tumors, 25-33% of the tumors localized in the posterior cranial fossa, and 80-94% of the tumors in the cerebellopontine angle (CPA). Schwannomas of other cranial nerves/trigeminal, facial, and schwannomas of the lower cranial nerves/are much less frequent. According to the World Health Organization (WHO), intracranial and intraspinal schwannomas are classified as Grade I. Some VS are found incidentally, but most present with hearing loss (95%), tinnitus (63%), disequilibrium (61%), or headache (32%). The neurological symptoms of VSs are mainly due to compression on the surrounding structures, such as the cranial nerves and vessels, or the brainstem. The gold standard for the imaging diagnosis of VS is MRI scan. The optimal management of VSs remains controversial. There are three main management options-conservative treatment or "watch-and-wait" policy, surgical treatment, and radiotherapy in all its variations. Currently, surgery of VS is not merely a life-saving procedure. The functional outcome of surgery and the quality of life become issues of major importance. The most appropriate surgical approach for each patient should be considered according to some criteria including indications, risk-benefit ratio, and prognosis of each patient. The approaches to the CPA and VS removal are generally divided in posterior and lateral. The retrosigmoid suboccipital approach is a safe and simple approach, and it is favored for VS surgery in most neurosurgical centers. Radiosurgery is becoming more and more available nowadays and is established as one of the main treatment modalities in VS management. Radiosurgery (SRS) is performed with either Gamma knife, Cyber knife, or linear accelerator. Larger tumors are being increasingly frequently managed with combined surgery and radiosurgery. The main goal of VS management is preservation of neurological function - facial nerve function, hearing, etc. The reported recurrence rate after microsurgical tumor removal is 0.5-5%. Postoperative follow-up imaging is essential to diagnose any recurrence.

[Trigeminal neuromas: modern diagnosis and treatment]

Trigeminal neuroma (TN) is a benign neoplasm arising from trigeminal nerve sheath. The tumor can grow from any part of the nerve from the root in posterior cranial fossa to peripheral extracranial branches. Symptoms of trigeminal neuroma are variable and usually depend on location and dimensions of tumor. We present a review devoted to the problem of TN. Surgery was the only possible option in patients with TN for a long time. However, radiotherapy became one of the options and sometimes alternative to surgical treatment since the late 1980s. Besides active management of patients with TN, follow-up with regular radiographic control of small asymptomatic tumors also seems to be reasonable. When evaluating treatment outcomes, physicians consider quality of life and return to previous work and activity in addition to resection quality, neurological impairment, relapse-free period and tumor growth control. However, assessment of these indicators after certain treatment is rare. Thus, it is difficult to determine treatment strategy with maximum ratio of effectiveness and quality of life. Therefore, optimization of TN treatment is currently an urgent problem that requires further study.

A Giant Schwannoma Extending from Medial Portion of Middle Cranial Fossa to Parapharyngeal Space and Deep Parotid Space

Trigeminal schwannomas are rare tumours comprising 0.2% of all intracranial tumours and 0.5% of all head and neck tumours. Patients with trigeminal schwannomas presented with facial hypoesthesia and pain. We presented a case with left bulging oropharynx. The CT scan showed a 3.8x2.6x4.9cm left parapharyngeal tumour compressed to the oropharynx and middle cranial fossa. We performed 3 ways in two times of operation to excise the whole tumour. We chose the transoral approach for parapharyngeal space, trans-parotid approach for deep parotid part and the endoscopic endonasal trans-pterygoid approach and trans-maxillary with Canine fossa trephination for intracranial lesions. The pathology showed schwannoma. A huge schwannoma extended from intracranial to several spaces is difficult to resect just by one approach. We should separate the tumour to several parts by clinical image before the operation and design a plan to remove the whole tumour in different approach. The different space of tumour involvement had several ways to access. We needed to choose the less harm but with better surgical field.

Management of non-vestibular schwannomas in adult patients: a systematic review and consensus statement on behalf of the EANS skull base section. Part I: oculomotor and other rare non-vestibular schwannomas (I, II, III, IV, VI)

BACKGROUND

Non-vestibular schwannomas are relatively rare, with trigeminal and jugular foramen schwannomas being the most common. This is a heterogeneous 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 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 first of a three-part series describing non-vestibular schwannomas (I, II, III, IV, VI).

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 pre-operative 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 of these patients is complex, and for those which are symptomatic tumours, the paradigm is shifting towards the compromise between function preservation and progression-free survival.

Management of non-vestibular schwannomas in adult patients: a systematic review and consensus statement on behalf of the EANS skull base section Part II: Trigeminal and facial nerve schwannomas (CN V, VII)

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 second of a three-part series describing non-vestibular schwannomas (V, VII).

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 pre-operative 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 trigeminal and facial schwannoma. The aim of treatment is maximal safe resection with preservation of function. Careful thought is required to select the appropriate surgical approach. Most middle fossa trigeminal schwannoma tumours can be safely accessed by a subtemporal extradural middle fossa approach. The treatment of facial nerve schwannoma remains controversial.

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.

Surgical Outcome of Trigeminal Schwannomas

Simple Summary

Trigeminal schwannomas are the most common among non-vestibular schwannomas. Treatment of trigeminal schwannomas may be challenging due to critical anatomical relations and involvement of different aspects of the skull base. Advances in microsurgery have led to improved outcomes over the last decades, whereas in contrast, some advocate stereotactic radiotherapy as an effective therapy, controlling the tumor volume with few complications. In this manuscript, we present outcome and adverse events in a contemporary cohort of trigeminal schwannomas and discuss surgical advantages and disadvantages of different performed classic skull-base approaches.

Abstract

(1) Background: As resection of trigeminal schwannomas is challenging, due to anatomical involvement of the anterior, middle and posterior fossa, the appropriate approach is important. We report our experience with surgical resection of trigeminal schwannomas by simple and classic skull-base approaches. (2) Methods: We performed a retrospective single-center study including patients who underwent surgery for trigeminal schwannoma tumors between June 2007 and May 2020, concentrating on surgical technique, extent of resection, postoperative outcome and complications. (3) Results: We included 13 patients (median age 57.5 with range of 36-83 years, 53.8% (7/13) female. The most common preoperative clinical presentations were facial pain in six (46.2%), hypoacusis in four (30.8%), trigeminal nerve hypesthesia in 11 (V1 46.2% (6/13), V2 (61.5% (8/13), V3 46.2% (6/13)) and headache in three (23.1%) patients. In three cases, the tumor was resected in a two-stage technique. The intradural subtemporal approach was performed in six cases, the extradural technique in two cases, the retrosigmoid approach in five cases, a Kawase approach in two cases and the transnasal endoscopic approach in one case. The gross total resection rate was 76.9% (10/13) and the median follow-up time 24.0 (0–136) months. Three (23.1%) patients developed postoperative anesthesia in at least one branch of the trigeminal nerve. Trigeminal motor function was preserved in 11 (84.6%) patients. Ten of the 11 patients (76.9%) who reported decreased gustation, cerebellar ataxia, visual impairment, or headache improved postoperatively. Two (15.4%) patients exhibited minimal facial palsy (House and Brackmann II–III), which resolved during the follow-up. The total adverse event rate requiring surgical intervention during follow-up was 7.7%. Surgery-related mortality was 0%. (4) Conclusions: Trigeminal schwannomas are rare benign lesions with intra- and extracranial extension. Considering the low operative morbidity and satisfying functional outcome, gross total resection of trigeminal schwannomas is achievable by classic, but also individually tailored approaches. More invasive or combined techniques were not needed with meticulous surgical planning.

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.

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.

"Apoplectic" Recurrence of Massive Trigeminal Neurinomas: Report of 7 Cases

OBJECTIVE

The pattern of recurrence of large trigeminal neurinomas is analyzed on the basis of experience with 7 cases.

METHODS

This is a report of 7 cases of large trigeminal neurinomas that were operated on an average of 11 years earlier. After being relatively asymptomatic over the years, these patients worsened relatively suddenly in their neurologic symptoms and were reoperated.

RESULTS

Imaging showed massive recurrence with tumor having cystic and solid components with sizes ranging from 4.5-11 cm. In 4 cases, the cysts at the time of initial presentation and at the time of recurrence showed a well-defined fluid level within the fluid content of the cyst. During operation it was seen that the tumor contained "hemorrhagic" fluid that was under significant pressure. The solid component in the circumferential periphery of the cyst fluid was soft, necrotic, and vascular. The entire recurrence in the middle and posterior cranial fossa and in the extracranial compartment was "interdural" or within the dural confines. Radical tumor resection within the dural confines by deploying relatively small surgical exposure resulted in "unusually" rapid recovery in the symptoms. Histological examination of the tumor did not reveal any malignant transformation.

CONCLUSIONS

The cases add further insight to the growth pattern and characteristics of large trigeminal neurinomas.

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 19^th 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.

Endoscopic transorbital and endonasal approach for trigeminal schwannomas: a retrospective multicenter analysis (KOSEN-005)

OBJECTIVE

Trigeminal schwannomas are rare neoplasms with an incidence of less than 1% that require a comprehensive surgical strategy. These tumors can occur anywhere along the path of the trigeminal nerve, capable of extending intradurally into the middle and posterior fossae, and extracranially into the orbital, pterygopalatine, and infratemporal fossa. Recent advancements in endoscopic surgery have suggested a more minimally invasive and direct route for tumors in and around Meckel's cave, including the endoscopic endonasal approach (EEA) and endoscopic transorbital superior eyelid approach (ETOA). The authors assess the feasibility and outcomes of EEA and ETOA for trigeminal schwannomas.

METHODS

A retrospective multicenter analysis was performed on 25 patients who underwent endoscopic surgical treatment for trigeminal schwannomas between September 2011 and February 2019. Thirteen patients (52%) underwent EEA and 12 (48%) had ETOA, one of whom underwent a combined approach with retrosigmoid craniotomy. The extent of resection, clinical outcome, and surgical morbidity were analyzed to evaluate the feasibility and selection of surgical approach between EEA and ETOA based on predominant location of trigeminal schwannomas.

RESULTS

According to predominant tumor location, 9 patients (36%) had middle fossa tumors (Samii type A), 8 patients (32%) had dumbbell-shaped tumors located in the middle and posterior cranial fossae (Samii type C), and another 8 patients (32%) had extracranial tumors (Samii type D). Gross-total resection (GTR, n = 12) and near-total resection (NTR, n = 7) were achieved in 19 patients (76%). The GTR/NTR rates were 81.8% for ETOA and 69.2% for EEA. The GTR/NTR rates of ETOA and EEA according to the classifications were 100% and 50% for tumors confined to the middle cranial fossa, 75% and 33% for dumbbell-shaped tumors located in the middle and posterior cranial fossae, and 50% and 100% for extracranial tumors. There were no postoperative CSF leaks. The most common preoperative symptom was trigeminal sensory dysfunction, which improved in 15 of 21 patients (71.4%). Three patients experienced new postoperative complications such as vasospasm (n = 1), wound infection (n = 1), and medial gaze palsy (n = 1).

CONCLUSIONS

ETOA provides adequate access and resectability for trigeminal schwannomas limited in the middle fossa or dumbbell-shaped tumors located in the middle and posterior fossae, as does EEA for extracranial tumors. Tumors predominantly involving the posterior fossa still remain a challenge in endoscopic surgery.

"Interdural" Surgical Strategy for Lower Cranial Nerve Neurinomas-A Report of 14 Cases

OBJECTIVE

We describe the dural relationships and its surgical implications for large lower cranial nerve (CN) neurinomas. The study is based on surgical experience with 14 cases.

METHODS

During the period January 2014 to December 2019, 14 consecutive cases with large lower CN neurinomas were surgically treated with the aim of radical tumor resection.

RESULTS

There were 9 males and 5 females, ranging in age from 17 to 65 years. All patients were operated in a single stage. The principal surgical observation was that the entire extent of tumor, which included intracranial, jugular fossa, and extracranial components, was within the "dural" confines and the tumor adjoining critical neural and vascular structures was displaced around the dome of the tumor. Radical surgical resection was achieved in all cases. During the follow-up period that ranged from 3 to 71 months (average 32 months), no symptomatic recurrence was observed and no patient needed reoperation. At the time of last clinical follow-up, the lower CN function in all patients was better than at the time of presentation.

CONCLUSIONS

The "dural" cover of the lower CN neurinomas forms a strong and reliable plane of compartmentalization and allows safe tumor resection.

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.

Endoscopic Endonasal Resection of Schwannoma of Pterygopalatine Fossa

Trigeminal schwannomas are benign slow-growing tumors originating from the peripheral nerve sheath. They account for 0.1%-0.4% of all intracranial tumors and 1%-8% of all intracranial schwannomas.^1-3 While most of these tumors develop in the trigeminal ganglion within the middle fossa, trigeminal schwannomas can develop anywhere along the course of the trigeminal nerve. As a result, they can be intradural, interdural, and extradural.^4,5 Trigeminal schwannomas from the pterygopalatine fossa (PPF) are extremely rare and very difficult to remove because of limited access to this region and the rich neurovascular contents. Numerous traditional microsurgical approaches to the PPF have been described; however, they are more invasive with increased morbidity.^6,7 Therefore, endoscopic endonasal surgery is a feasible solution. This technique allows good visualization of the region with decreased morbidity and a shorter recovery period. A previously healthy, 40-year-old woman presented with right facial pain for 3 weeks. On neurologic examination, the patient had hypoesthesia in the territory of the maxillary (V2) branch of the right trigeminal nerve. She had no other symptoms on physical examination. Cranial computed tomography and magnetic resonance imaging were performed and showed a high signal density mass in the right PPF that exhibited heterogeneous contrast enhancement. She was initially treated with low-dose carbamazepine; however, the dose could not be further increased because of drowsiness and dizziness. Given the size and location of the mass, an endoscopic endonasal approach was performed, and the tumor was successfully resected (Video 1). The postoperative course was uneventful, and the patient had significant improvement of her symptoms and was discharged with no new neurologic deficits. However, she continued to have hypoesthesia of the V2 segment of the trigeminal nerve.

Parasellar Schwannomas: Extradural vs Extra-Intradural Surgical Approach

BACKGROUND

Schwannomas of the parasellar region may arise from the trigeminal, oculomotor, trochlear, and abducens nerves.

OBJECTIVE

To define the tumor origin, location, and dural relationship (extradural vs extra-intradural vs cisternal) on preoperative magnetic resonance imaging (MRI), in order to plan the best surgical approach (purely extradural vs extra-intradural).

METHODS

Twenty-four patients with parasellar schwannomas who underwent surgery were retrospectively analyzed. Twenty arose from the trigeminal nerve (7 intracavernous and 13 within the Meckel's cave), 3 from the oculomotor nerve, and 1 from the abducens nerve. The preoperative identification of the tumor location (extradural vs extra-intradural vs cisternal) and the nerve of origin was defined on MR sequences. All patients were operated on through a pterional approach (extradural or extra-intradural route).

RESULTS

The tumor location was correctly defined on MRI in 22 out of 24 cases (92%) and the nerve of origin in 22 (92%). An extradural approach without intradural exploration was performed in all 5 intracavernous trigeminal schwannomas, in 11 out of 13 of the Meckel's cave, and in 2 schwannomas of the oculomotor nerve. Two schwannomas of the Meckel's cave with transgression of the medial dural wall, 1 of the oculomotor nerve, and the abducens nerve schwannoma required an extra-intradural approach. Complete tumor resection was obtained in 19 out of 24 cases (80%).

CONCLUSION

The pterional extradural approach is sufficient for Dolenc type I and II trigeminal schwannomas, excepting for those transgressing the inner dural layer. Schwannomas of the oculomotor and abducens nerves with cisternal location require an extradural-intradural approach.

Intradural Subtemporal Keyhole Approach with Neuronavigational Assistance to the Petroclival and Ventrolateral Brainstem Regions: Quantitative Analysis of Anatomic Exposure and Surgical Freedom

OBJECTIVE

The purpose of this study was to evaluate the advantages of endoscopy and navigational assistance in the intradural subtemporal keyhole approach and the intradural Kawase approach by studying anatomic exposure and surgical freedom in the posterior cranial fossa.

METHODS

Twenty endoscopic intradural subtemporal keyhole approaches (EISKA) were performed on 10 cadaveric heads. An intradural Kawase approach and a navigation-assisted intradural Kawase approach were then carried out on a random side of each specimen. Related anatomic structures were observed through a 0° endoscope and a microscope. Anatomic exposure and surgical freedom were measured by transparent graph paper and analyzed.

RESULTS

Compared with the microsurgical technique, the superior, inferior, and medial limits of the endoscopic anatomic exposure increased by 2.9, 15.65, and 10.2 mm, whereas the surgical freedom increased by 2.9, 7.55, and 6 mm (P < 0.05) in the intradural subtemporal keyhole approach. In the intradural Kawase approach and the navigation-assisted intradural Kawase approach, the endoscopic anatomic exposure and surgical freedom also increased (P < 0.05). Using a frameless navigational device, the inferior limit of the anatomic exposure increased 3.8 mm by endoscopy and 3.5 mm by microscopy, whereas the surgical freedom increased by 2.7 and 2.2 mm, respectively (P < 0.05).

CONCLUSIONS

The EISKA provides greater anatomic exposure and surgical freedom primarily in the superior, inferior, and medial directions of the brainstem region. Maximum anatomic exposure and surgical freedom of the posterior cranial fossa was obtained by navigational assistance with fewer complications.

Trigeminal Schwannomas in Middle Fossa Could Breach into Subdural Space: Report of 4 Cases and Review of Literature

OBJECTIVE

The objectives of this study were to report 4 cases diagnosed with trigeminal schwannomas (TS), among whom tumor in epidural space of middle fossa broke through dura mater into subdural space, and to analyze the potential reason for recurrence of TS in middle fossa after surgical removal by endoscopic endonasal approach (EEA) or interdural approach.

METHODS

The information of 4 patients diagnosed with TS who were surgically treated was retrospectively analyzed and the selection of approaches, surgical strategies, and potential reason for recurrence after middle fossa TS removal by EEA and interdural approach were discussed.

RESULTS

During last 10 years, 43 patients with TS received surgical treatment at Xuan Wu Hospital of Capital Medical University, among whom 1 patient with TS extending from middle fossa to infratemporal fossa was first treated by EEA, then the tumor recurred and the patient underwent a second operation via a frontotemporal subdural approach. During the second operation, we found part of tumor had broken through the dura mater into subdural space. Moreover, this phenomenon was detected in another 3 patients with middle-posterior fossa TS.

CONCLUSIONS

TS in middle fossa has been widely believed to be totally located at epidural space, whereas we found that it could occasionally breach into subdural space and accept blood supply from the pial artery. We believe this could be the potential reason for recurrence after tumor resection by EEA and interdural approach.

Microsurgical Management of Trigeminal Schwannoma: Cohort Analysis and Systematic Review

Background  Trigeminal schwannomas are benign tumors with a predilection for women between 40 and 60 years of age and account for less than 0.5% of all intracranial tumors. Clinical presentation depends on size and location, and typical symptoms are ipsilateral hypesthesia, headache, and facial pain. Clinical features and imaging usually make the Diagnosis. Methods  A retrospective cohort analysis of 14 patients treated at our institution between January 1999 and October 2016 was performed, with a critical and systematic review of data from the literature, focusing on articles published over the same period. Results  Fourteen patients were included in our series comprised of mostly women with a mean age of 40 years. Lesion size ranged from 3 to 6.5 cm (mean 4.6 cm). Clinical status of patients was evaluated and also rated based on the Karnofsky Perfomance Scale with values greater than 90% found in all patients pre and postoperatively. Surgery was our treatment of choice, and gross total resection was achieved in 71% of patients. Associated morbidity was high at 57%, predominantly from cranial nerve palsy, and no deaths were encountered. Conclusions  Microsurgery is a suitable treatment for large symptomatic trigeminal schwannomas, achieving good local control rates over the observation period at acceptable morbidity. Therefore, microsurgery appears to a suitable option. During the study period, a significant evolution in the availability of treatment methods occurred. Radiosurgery emerged as an alternative treatment for unresectable lesions. A comprehensive review of the available literature was performed, and results were compared according to treatment modality.

Endoscopically Assisted Targeted Keyhole Retrosigmoid Approaches for Microvascular Decompression: Quantitative Anatomic Study

OBJECTIVE

We describe and quantitatively assess minimally invasive keyhole retrosigmoid approaches targeted to the upper, middle, and lower cranial nerve (CN) complexes of the cerebellopontine angle (CPA).

METHODS

Anatomic dissections were performed on 10 sides of 5 fixed, silicone-injected cadaver heads. Surgical views through various trajectories were assessed in endoscopic videos and 3-dimensional (3D) interactive virtual reality microscope views. Surgical freedom and angles of attack to the proximal and distal areas of CN complexes of the CPA were compared among upper and lower keyholes and conventional retrosigmoid craniotomy using neuronavigation.

RESULTS

Compared with keyholes, the conventional approach had superior surgical freedom to most areas except for the distal CN V, the root of CN VII, and the root of CN IX, where differences were not significant. The conventional retrosigmoid approach provided a larger horizontal angle of attack than either the upper or lower keyholes for all selected areas; however, the vertical angles of attack were not different. Splitting the petrosal fissure resulted in a significant increase in the vertical angle of attack to the root zones of CNs V and VII but not to the distal areas of these nerves or CN IX. Illustrative cases of endoscope-assisted keyhole retrosigmoid approaches for the treatment of trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia are presented.

CONCLUSIONS

Targeted keyhole retrosigmoid approaches require detailed understanding of the 3D anatomy of the CPA to create appropriate locations of corridors, including skin incisions and keyholes. Endoscope assistance complements the standard microsurgical technique by maximizing the visualization and identification of the delicate neurovascular structures.

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.

Trigeminal schwannoma presenting as a gelastic seizure: no laughing matter

We present the case of a 66 year old gentleman with trigeminal schwannoma whose only presenting feature was a single gelastic seizure. This is the first case report of pathological laughter in trigeminal schwannoma in the absence of other trigeminal, brainstem, cerebellar or other cranial nerve dysfunction.

Single Stage Complete Removal of Dumbbell Trigeminal Schwannoma in a Child by Skull Base Approach

Trigeminal schwannomas (TSs) are extremely rare tumors in childhood, particularly in the absence of neurofibromatosis. Although multi-staged surgical strategies have been reported in the literature, safe and single stage microsurgical removal is possible. We report a rare case of dumbbell TS, in a 9-year-old girl in whom single stage complete removal was done using fronto-temporo-orbito-zygomatic craniotomy and sub temporal approach.

Giant trigeminal schwannomas-case report and a short literature review

Trigeminal schwannomas (TS) are rare tumors that are located in the posterior and middle cranial fossae in about a quarter of the cases. The presentation pattern is different according to the involved compartment and the goal of surgery is complete removal. We present the case of a 35-year old woman who presented a left sided TS extending from the posterior to the middle fossa and cavernous sinus. We review the relevant literature regarding diagnosis and surgical treatment of these tumors.

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.

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.