Trigeminal schwannomas: removal of dumbbell-shaped tumors through the expanded Meckel cave and outcomes of cranial nerve function

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.

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.

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.

Postoperative trigeminal neuropathy outcomes following surgery for tumors involving the trigeminal nerve

OBJECTIVE

To observe the evolution and outcomes of postoperative trigeminal neuropathy following surgery of tumor involving the trigeminal nerve.

METHODS

A prospective observational study was conducted between October 2018 and February 2019 involving 25 patients with tumors confirmed to involve the trigeminal nerve during surgery by senior author. Pre- and postoperative trigeminal nerve function status and clinical data were recorded.

RESULTS

This study included 18 cases of meningioma and seven of trigeminal schwannoma. Among the meningioma cases, 55.6% of the patients reported facial sensory dysfunction before surgery, 33.3% presented ocular discomfort, and 5.6% had masticatory muscle atrophy. Postoperatively, all patients experienced facial paresthesia, 94.4% complained of eye dryness, and one (5.56%) exhibited keratitis. Additionally, one patient (5.56%) showed new-onset masticatory weakness. During follow-up, 50.0% of patients reported improvement in facial paresthesia, and one (5.56%) experienced deterioration. Eye dryness resolved in 35.3% of patients, and keratitis remission was observed in one patient. However, one patient (5.56%) developed neurotrophic keratitis. Overall, 55.6% of patients displayed mild masticatory weakness without muscle atrophy. In the cases of schwannoma, 28.6% of patients had facial paresthesia before surgery, 42.9% showed ocular discomfort, and one (14.3%) complained of masticatory dysfunction. Postoperatively, 85.7% of patients reported facial paresthesia and eye dryness, with one patient (16.7%) experiencing keratitis. During follow-up, 66.7% of patients demonstrated improvement in facial paresthesia, 28.6% showed eye dryness remission, and one patient (16.7%) recovered from keratitis. However, one patient (16.7%) developed new-onset neurotrophic keratitis. One patient (16.7%) experienced relief of masticatory dysfunction, but 42.9% reported mild deterioration. Another patient (14.3%) had facial anesthesia that had not improved.

CONCLUSION

Postoperative trigeminal neuropathy is a common complication with a high incidence rate and poor recovery outcomes after surgery for tumors involving the trigeminal nerve. When trigeminal nerve damage is unavoidable, it is essential to provide a multidisciplinary and careful follow-up, along with active management strategy, to mitigate the more severe effects of postoperative trigeminal neuropathy.

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.

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.

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.

Simplified anterior transpetrosal approach without superior petrosal sinus and tentorial incision for lesions centered in Meckel's cave

OBJECTIVE

The anterior transpetrosal approach (ATPA) is an effective method to reach lesions in the petroclival region. This approach involves many steps, including superior petrosal sinus (SPS) ligation and tentorial cutting. It is sometimes unnecessary to perform all procedures in the ATPA for certain lesions, especially those centered in the Meckel's cave. Here, we present a simplified anterior transpetrosal approach (SATPA) without superior petrosal sinus and tentorial incision for lesions centered in the Meckel's cave as a modified ATPA.

METHODS

This study included 13 patients treated with SATPA. The initial steps of SATPA are similar to ATPA, excluding a middle cranial fossa dural incision, SPS dissection, or tentorial incision. Histological examination was performed to understand the membrane structure of the trigeminal nerve, which runs through the Meckel's cave.

RESULTS

Pathology revealed trigeminal schwannoma (n=11), extraventricular central neurocytoma (n=1), and a metastatic tumor (n=1). The average tumor size was 2.4 cm. The total removal rate was 76.9% (10/13). Permanent complications included trigeminal neuropathy in four cases and cerebrospinal fluid leakage in one case. Histological examination revealed the trigeminal nerve traverses the subarachnoid space from the posterior fossa subdural space to the Meckel's cave and is covered with the epineurium in the inner reticular layer.

CONCLUSIONS

We used SATPA for lesions located in the Meckel's cave identified using histological examination. This approach may be considered for small- to medium-sized lesions centered in the Meckel space.

CLINICAL TRIAL REGISTRATION NUMBER

None.

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.

Orbito-cranial schwannoma-a multicentre experience

OBJECTIVES

To describe the features, management approaches, and outcomes of orbito-cranial schwannomas.

METHODS

Retrospective review of ten patients with orbito-cranial schwannomas managed in six orbital services over 22 years. Data collected included demographics, presenting features, neuroimaging characteristics, histology, management approach, complications, and outcomes.

RESULTS

Mean age of the patients was 41.4 ± 19.9 years, and 6 (60%) were females. The majority presented with proptosis (90%), limited extraocular motility (80%), eyelid swelling (60%), and optic neuropathy (60%). Most lesions (80%) involved the entire anterior-posterior span of the orbit, with both intra- and extraconal involvement. All tumours involved the orbital apex, the superior orbital fissure, and extended at least to the cavernous sinus. Surgical resection was performed for all. Seven (70%) of the tumours were completely or subtotally resected combining an intracapsular approach by an orbital-neurosurgical collaboration, with no recurrence on postoperative follow-up (6-186 months). Three underwent tumour debulking. Of these, two remained stable on follow-up (6-34 months) and one showed progression of the residual tumour over 9 years (cellular schwannoma on histology) necessitating stereotactic radiotherapy (SRT) for local control. Adjuncts to the orbito-cranial resection included perioperative frozen section (n = 5), endoscopic transorbital approach (n = 2), and image-guided navigation (n = 1). Post-surgical adjuvant SRT was used in three subjects.

CONCLUSIONS

These results highlight the possibility of successful surgical control in complex orbito-cranial schwannomas. A combined neurosurgical/orbital approach with consideration of an intracapsular resection is recommended. Recurrence may not occur with subtotal excision and observation may be reasonable. Adjunctive SRT for progression or residual tumour can be considered.

Schwannomas of the greater superficial petrosal nerve - case series, discussion of surgical techniques, and review of literature

BACKGROUND

Facial nerve schwannomas account for about 0.8% of all petrous mass lesions. Schwannomas of the greater superficial petrosal nerve (GSPN) are a rare subtype with few case-reports up to date.

CASE PRESENTATIONS

A retrospective analysis of clinical outcomes, radiographic findings and postoperative complication between June 2007 and December 2020 was performed. Four cases of GSPN schwannomas were reported. The presenting symptoms were facial nerve palsy and hearing loss. Imaging studies showed a subtemporal mass on the anterosuperior aspect of the petrous bone, in one case with extraordinary petrous bone and mastoid infiltration and destruction. Three cases were removed through a subtemporal extra- or intradural approach, one case via a combined pre- and retrosigmoid approach. Improvement of facial nerve palsy occurred in one case; new hearing loss was observed in another case. Xeropthalmia was a short-term temporary deficit in three cases. Short- to mid-term follow-up of the patients has not shown any tumor recurrence.

CONCLUSIONS

GSPN schwannomas are rare entities presenting with heterogenous symptoms. Our surgical findings emphasize safe resection. Complete remission is possible by GTR. Since the small data set limits the expressiveness of statements regarding standard of care and alternative therapy options, additional data is needed.

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.

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.

Petrous bone lesions: surgical implementation and outcomes of extradural subtemporal approach

BACKGROUND

Petrous bone lesions (PBLs) are rare with few reports in the neurosurgical literature. In this study, the authors describe our current technique of extradural subtemporal approach (ESTA). The objective of this study was to evaluate the role and efficacy of ESTA for treatment of the PBLs. To our knowledge, this is the largest reported clinical series of using an ESTA-treated PBLs in which the clinical outcomes were evaluated.

METHODS

Between 1994 and 2019, 67 patients with PBLs treated by ESTA were retrospectively reviewed. Extent of resection, neurological outcomes, recurrence rate, and surgical complications were evaluated and compared with previous studies. The indications, advantages, limitations, and outcomes of ESTA were analyzed according to pathology.

RESULTS

This series included 7 facial nerve schwannomas (10.4%), 16 cholesterol granulomas (23.9%), 16 chordomas (23.9%), 6 chondrosarcomas (9%), 5 trigeminal schwannomas (7.5%), 9 epidermoids/dermoids (13.4%), and 8 other pathologies (11.9%). The most common location of PBLs operated with ESTA was at the petrous apex and rhomboid areas (68.7%). Gross total resection was achieved in 35 (55.6%). Symptomatic improvement occurred in 56 patients (83.6%). Complications occurred in 7 (10.4%) of cases including one mortality. Nine patients (17%) had recurrence within the mean follow-up 71 months. Compared to previous literature, our results demonstrated comparable outcomes but with higher rates of hearing and facial nerve preservation as well as minimal morbidity. From our results, ESTA is an effective therapeutic option for lesions located at the rhomboid and petrous apex, particularly when patients presented with intact facial and hearing function.

CONCLUSION

Our series demonstrated that ESTA provided satisfactory outcomes with excellent benefits of hearing and facial function preservation for patients with petrous bone lesions. ESTA should be considered as a safe and effective therapeutic option for selected patients with PBLs.

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.

Anterior Petrosal Approach for Enlarging Previously Radiated Recurrent Trigeminal Schwannoma: 2-Dimensional Operative Video

Trigeminal nerve schwannomas (TNSs) are rare lesions that typically present with symptoms of trigeminal neuropathy or other cranial nerve palsies. These lesions classically have a dumbbell shape, with an anterior component within Meckel's cave and posterior component extending into the posterior fossa through the porus trigeminus. Surgical resection of TNSs can often be achieved via an extradural subtemporal approach to Meckel's cave without an anterior petrousectomy, even for tumors with a significant posterior fossa component, as the tumor often erodes a portion of the petrous apex.1 We present the case of a 53-yr-old female presenting to our institution with complete trigeminal neuropathy secondary to a right-sided, previously resected and radiated TNS. Serial imaging demonstrated an interval growth of significant residual tumor despite multiple adjuvant therapies, and, thus, the patient was recommended to undergo additional surgical resection. The lesion was approached through a right-sided subtemporal approach to Meckel's cave,2 with a plan to utilize an anterior petrousectomy only if difficulty resecting the posterior fossa component of the tumor was encountered. Intraoperatively, the posterior fossa component was found to be densely adherent to the adjacent brainstem, likely secondary to prior surgery and radiation therapy, and, thus, an anterior petrousectomy was performed. Postoperatively, the patient had stable trigeminal neuropathy without any new neurological deficits and a magnetic resonance imaging (MRI) confirmed a gross total resection. In the accompanying video, we hope to demonstrate the steps and nuances of both the subtemporal approach to accessing Meckel's cave and anterior petrousectomy when employed for the resection of TNSs. The patient in question provided formal consent for the making of this video.

Petrosal Approach With Preservation of the Superior Petrosal Sinus (the Graceful Petrosal) for Resection of Giant Trigeminal Schwannoma: 2-Dimensional Operative Video

Trigeminal schwannomas are benign tumors amendable to curative surgical resection.1 Excellent outcomes, with preservation and improvement of cranial nerve function, including trigeminal nerve function, have been reported with microsurgical resection through skull base approaches.2 Dumbell shaped tumors, involving the middle and posterior fossa, are more challenging.3 They are resected via a middle cranial fossa approach with the expanded Meckel cave providing access to the posterior fossa. However, tumors with a large caudal extension below the internal auditory meatus typically cannot be adequately accessed with this approach and the posterior petrosal approach is utilized.2 Specific venous anatomy might deter from cutting the tentorium. This article describes the surgical resection of a trigeminal schwannoma with a large posterior fossa component through a petrosal approach without cutting the tentorium.4 The patient is a 34-yr-old man who presented with headaches and gait disturbance. Neurological exam revealed hypoesthesia and hypoalgesia in the left V1 and V2 distributions. Magnetic resonance imaging (MRI) revealed a large dumbbell-shaped schwannoma causing brainstem compression. Magnetic resonance venography (MRV) demonstrated temporal lobe venous drainage into the superior petrosal sinus and tentorium proximal to the transverse sigmoid junction. A single temporal-suboccipital bone flap and a retro-labrynthine mastoidectomy were performed. The petrous apex was drilled and Meckle's cave opened. The presigmoid dura was opened and extended toward the petrous apex region beneath the tentorium. This provided access to and safe resection of the tumor. A gross total tumor resection was achieved. The patient remained stable neurologically and was without tumor recurrence at 3 yr postoperatively. The patient had consented to the procedure. Figures in video at 4:06 from Jafez et al, Preservation of the superior petrosal sinus during the petrosal approach, J Neurosurg. 2011;114(5):1294-1298, with permission from JNSPG.

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.

Meckel's Cave and Somatotopy of the Trigeminal Ganglion

BACKGROUND

The anatomy and spatial relationships of the dural sac comprising the Meckel cave (MC) and its ensheathed trigeminal ganglion (TG) are exceedingly intricate and complex. There are conflicting accounts in the literature regarding the dural configuration of the MC around the ganglion and the dual embryology of the MC and TG is still unclear.

METHODS

A combined systematic and narrative literature review was conducted to collate articles addressing MC and TG anatomy, in addition to their embryology, role in tumor spread, somatotopy, and association with trigeminal neuralgia.

RESULTS

Three key anatomic models by Paturet (1964), Lazorthes (1973), and Lang and Ferner (1983) have been put forward to show the arrangement of the MC around the TG. The TG is formed from both neural crest and placodal cells and drags the enveloping dura caudally to form the MC prolongation during development. Both a mediolateral and dorsoventral somatotopic arrangement of neurons exists in the TG, which corresponds to the 3 nerve divisions, of which V2 and V3 are prone to perineural tumor spread along their course.

CONCLUSIONS

Sound knowledge concerning the dural arrangement of the MC and the trigeminal divisions will be invaluable in optimally treating cancers in this region, and understanding TG somatotopy will immensely improve treatment of trigeminal neuralgia in terms of specificity, efficacy, and positive patient outcomes.

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.

Reappraisal of the types of trigeminal porus and importance in surgical applications

OBJECTIVE

The detailed information regarding the types of trigeminal porus (TP) and related surgical approach is lacking in the literature. Therefore, we performed this study to elucidate further the types of TP and the relationships with critical surgical landmarks in the skull base.

METHODS

The study was performed on 19 formalin-fixed cadavers of the cranial base (52.6% male, n = 10; 47.4% female, n = 9) on both sides. Calculations were made of the vertical dimension (VD), horizontal dimension (HD), and types of TP, the thickness of the TP, the HD and VD of the internal acoustic meatus, the distance between the TP-IAM, the thickness of the ossifying tissue that forms the TP, the trigeminal nerve (CN V) in both types and the distance between the CN V-VI.

RESULTS

The elliptical (42.1% left, 36.8% right), oval (52.6% left, 36.8% right) and slit-like (5.3% right) types of TP were detected (X² = 11.722). The HD of the TP was, on average, 8.02 mm (female) and 9.2 mm (male) on the right side, and 8.26 mm (female) and 8.81 mm (male) on the left side. The VD of the TP was, on average, 1.99 mm (female) and 2.65 mm (male) on the right side, and 2.42 mm (female) and 2.94 mm (male) on the left side.

CONCLUSIONS

In our study, ellipse and slit-like types of TP are taken into account in order to plan the surgical approaches to remove or prevent the extension of tumors. A combined surgical technique is recommended to reach the TP easily without damaging the nearby surgical structures during surgery. The oval type of TP allows a wide range of movements, so it is more advantageous in skull base surgery.

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.

Electrophysiological predictors of hearing deterioration based on AEP monitoring during petroclival meningioma resection

The objective of this study was to calculate the risk of postsurgical hearing deterioration as a function of changes in the amplitude and latency of the most stable components (waves III and V) of the auditory evoked potential (AEP) during petroclival meningioma resection surgery. We retrospectively analyzed intraoperative AEP monitoring results and pre- and postsurgical hearing status in 40 consecutive patients who were surgically treated for petroclival meningiomas. Statistical analyses were conducted to identify the most sensitive and specific way to predict hearing dysfunction after surgery. Patients' mean age was 59 ± 10 years, and 31 (77.5%) were women. Twelve (30%) patients presented with clinically detectable hearing impairment preoperatively. At the first postoperative assessment, four of those 12 patients reported subjective improvement, and eight reported hearing deterioration. Of those eight, four remained stable and four recovered hearing by the last assessment. Wave III latency reached its highest specificity (100%) and sensitivity (71.43%) at x = 143%. Wave V latency, on the other hand, reached its highest sensitivity (71%) and specificity (93%) at x = 124%. Finally, wave V amplitude reached its highest sensitivity (100%) and specificity (79%) at x = 74%. Intraoperative alterations of wave III latency and wave V amplitude seem to be highly sensitive and specific at predicting the risk of auditory dysfunction in patients undergoing petroclival meningioma resection and should be used to determine maximum resection with preservation of function.

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.

Anterior Clinoidal Meningiomas: Meningeal Anatomical Considerations and Surgical Implications

Objective: Surgical removal of anterior clinoidal meningiomas (ACMs) remains a challenge because of its complicated relationship with surrounding meninges, major arteries and cranial nerves. This study aims to define the meningeal structures around the anterior clinoid process (ACP) and its surgical implications.

Methods: Five dry skulls and 19 cadavers were used in the anatomical study. Cadavers were prepared as transverse, coronal, and sagittal plastinated sections, and the meningeal architecture around the ACP was studied with dissecting and confocal microscopies. The database of meningiomas in one single center was retrospectively reviewed, and the patients with ACMs were collected for clinical analysis.

Results: The superior, lateral, medial surfaces, and the tip of ACP were covered by different layers and types of meninges. The ACMs were classified into four main types based on the sites of origin, possible extending pathways following meningeal dura. In the retrospective cohort of 131 ACMs, the percentage of types I, IIa, IIb, III, and IV were 42.0% (55/131), 19.8% (26/131), 9.2% (12/131), 16.8% (22/131), and 12.2% (16/131), respectively. We found that types IIa and I had higher chances for achieving Simpson grade 1–2 resection (92.3 and 85.4%, respectively), followed by type III (54.5%) and type IV (31.3%), while type IIb showed little chance of Simpson grade 1–2 resection. Univariate and multivariate analyses revealed ACM classification and tumor size (<3 cm) to be independent risk factors for achieving more extensive resection.

Conclusion: The meningeal architecture around the ACP may guide and determine the origin and extension of ACMs. The classification based on the meningeal architecture helps to understand surgical anatomy as well as predicting surgical outcomes.

Single-stage endoscopic endonasal approach for the complete removal of trigeminal schwannomas occupying both the middle and posterior fossae

To introduce a purely endoscopic endonasal trans-Meckel's cave approach or a transclival approach for trigeminal schwannomas (TSs) involving both the middle and posterior fossae. This retrospective study reviewed the medical records and intraoperative videos of 8 patients with TSs occupying both the middle and posterior fossae who underwent an endoscopic endonasal approach (EEA) between January 2017 and October 2019. All 8 patients received total resection under a single-stage EEA. Six patients underwent endoscopic endonasal resection via a purely trans-Meckel's cave approach, and 2 patients underwent endoscopic endonasal resection via a trans-Meckel's cave approach combined with a transclival approach. There was no surgical-related hemorrhage or mortality and no cerebrospinal fluid leakage. All headache symptoms completely improved postoperatively (n = 3 patients). All cranial nerve (CN) symptoms (CN IX and CN VI) improved postoperatively. The most common preoperative symptom was facial numbness (n = 5 patients); 2 of these 5 patients showed a partial improvement, 1 patient experienced worsening, and 2 patients remained unchanged at the last follow-up. Four patients developed postoperative complications, including CN VI palsy (n = 2), dry eye (n = 2), mastication weakness (n = 1), and facial numbness (n = 2). All complications except for dry eye were relieved at the last follow-up, but the patients with dry eye did not develop corneal keratopathy. The endoscopic endonasal trans-Meckel's cave and transclival approaches provide adequate exposure and improve the rate of total resection for TSs occupying both the middle and posterior fossae with minimal invasion. It may be possible to use these approaches as a safe alternative to conventional surgical approaches.

Endoscopic transorbital surgery for Meckel's cave and middle cranial fossa tumors: surgical technique and early results

OBJECTIVE

Tumors involving Meckel's cave remain extremely challenging because of the surrounding complex neurovascular structures and deep-seated location. The authors investigated a new minimal-access technique using the endoscopic transorbital approach (eTOA) through the superior eyelid crease to Meckel's cave and middle cranial fossa lesions and reviewed the most useful surgical procedures and pitfalls of this approach.

METHODS

Between September 2016 and January 2018, the authors performed eTOA in 9 patients with tumors involving Meckel's cave and the middle cranial fossa. The lesions included trigeminal schwannoma in 4 patients, meningioma in 2 patients, metastatic brain tumor in 1 patient, chondrosarcoma in 1 patient, and dermoid cyst in 1 patient. In 7 of the 9 patients, eTOA alone was performed, while the other 2 patients underwent a combined eTOA and endoscopic endonasal approach or retrosigmoid craniotomy. Data including details of surgical techniques and clinical outcomes were recorded.

RESULTS

Gross-total resection was performed in 7 of the 9 patients (77.8%). Four patients underwent extended eTOA (with lateral orbital rim osteotomy). Drilling of the trapezoid sphenoid floor, a middle fossa "peeling" technique, and full visualization of Meckel's cave were applied to approach the lesions. Tumors were exposed and removed extradurally in 3 patients and intradurally in 6 patients. There was no postoperative CSF leak.

CONCLUSIONS

The eTOA affords a direct route to access Meckel's cave and middle cranial fossa lesions. With experience, this novel approach can be successfully applied to selected skull base lesions. To achieve successful removal of the tumor, emphasis should be placed on the importance of adequately removing the greater sphenoid wing and vertical crest. However, because of limited working space eTOA may not be an ideal approach for posterior fossa lesions.

Extended exposure of the petroclival junction: The combined anterior transpetrosal and subtemporal/transcavernous approach

Background:

The combined anterior transpetrosal and subtemporal/transcavernous (atsta) approach to the petroclival junction provides a wide exposure facilitating resection of large tumor lesions such as petroclival mengiomas, chondrosarcomas, or chordomas. In this article we provide technical instructions on the approach with anatomical consideration and a literature review of previous applications of this approach.

Methods:

The combined approach was performed in two cadaveric specimen and relevant anatomical aspects were studied. Additionally, the authors performed a review of the literature focusing on indications, neurologic outcome, and complications associated with the technique.

Results:

A combined atsta approach offers a wide exposure of the crus cerebrum, pons, basal temporal lobe, cranial nerves III to VII/VIII, posterior cerebral artery (PCA), superior cerebellar artery (SCA), basilar artery (BA), anterior inferior cerebellar artery (AICA), and posterior communicating artery (Pcom). It has been successfully applied with acceptable morbidity and mortality rates, mainly for (spheno-) petroclival meningiomas.

Conclusion:

The combined approach studied here is a useful skull base approach to the petroclival junction and can be applied to treat large or complex pathologies of the region. Detailed anatomical knowledge is essential.

Endoscopic anterior transmaxillary "transalisphenoid" approach to Meckel's cave and the middle cranial fossa: an anatomical study and clinical application

OBJECTIVE Multiple approaches have been designed to reach the medial middle fossa (for lesions in Meckel's cave, in particular), but an anterior approach through the greater wing of the sphenoid (transalisphenoid) has not been explored. In this study, the authors sought to assess the feasibility of and define the anatomical landmarks for an endoscopic anterior transmaxillary transalisphenoid (EATT) approach to Meckel's cave and the middle cranial fossa. METHODS Endoscopic dissection was performed on 5 cadaver heads injected intravascularly with colored silicone bilaterally to develop the approach and define surgical landmarks. The authors then used this approach in 2 patients with tumors that involved Meckel's cave and provide their illustrative clinical case reports. RESULTS The EATT approach is divided into the following 4 stages: 1) entry into the maxillary sinus, 2) exposure of the greater wing of the sphenoid, 3) exposure of the medial middle fossa, and 4) exposure of Meckel's cave and lateral wall of the cavernous sinus. The approach provided excellent surgical access to the anterior and lateral portions of Meckel's cave and offered the possibility of expanding into the infratemporal fossa and lateral middle fossa and, in combination with an endonasal transpterygoid approach, accessing the anteromedial aspect of Meckel's cave. CONCLUSIONS The EATT approach to Meckel's cave and the middle cranial fossa is technically feasible and confers certain advantages in specific clinical situations. The approach might complement current surgical approaches for lesions of Meckel's cave and could be ideal for lesions that are lateral to the trigeminal ganglion in Meckel's cave or extend from the maxillary sinus, infratemporal fossa, or pterygopalatine fossa into the middle cranial fossa, Meckel's cave, and cavernous sinus, such as schwannomas, meningiomas, and sinonasal tumors and perineural spread of cutaneous malignancy.

Comprehensive review of the extended middle cranial fossa approach

PURPOSE OF REVIEW

To review the current literature on the extended middle cranial fossa (xMCF) approach and to provide a comprehensive description of the relevant anatomy, indications, surgical technique, results, and complications.

RECENT FINDINGS

The xMCF approach expands the surgical exposure provided by the sMCF approach, allowing access to the internal auditory canal, cerebellopontine angle, prepontine cistern, anterior petrous apex, petrous carotid artery, Meckel's cave, cavernous sinus, mid and upper clivus, and posterior lesions approaching the jugular foramen. Preservation of serviceable hearing is possible with success rates approximating 50% in vestibular schwannoma and meningioma resection, and facial nerve outcome is excellent.

SUMMARY

The xMCF is an important approach for difficult to access lesions that additionally offers the possibility of hearing preservation. This approach is also useful for vascular lesions, auditory brainstem implantation, and lesions of mid-brainstem.

Surgical Management of Tumors Involving Meckel's Cave and Cavernous Sinus: Role of an Extended Middle Fossa and Lateral Sphenoidectomy Approach

OBJECTIVE

To study the indications and outcomes of lateral sphenoidectomy as part of a combined skull base approach in the treatment of tumors involving Meckel's cave (MC) and cavernous sinus (CS).

STUDY DESIGN

Retrospective patient series.

SETTING

Tertiary referral center.

PATIENTS

Twenty-two consecutive patients (mean age: 45 yr, range: 16-76) who underwent transzygomatic, extended middle fossa approaches for tumors involving MC and CS.

INTERVENTIONS

Surgical access to MC and CS was achieved via extended middle fossa, trans-clinoid approach. Lateral sphenoidectomy was defined as drill-out of the greater sphenoid wing lateral to foramen rotundum and ovale, decompression of superior orbital fissure, and removal of anterior clinoid process. Reconstruction was achieved using combination of autologous and synthetic materials. Eleven patients (50%) received adjuvant radiation.

MAIN OUTCOME MEASURES AND RESULTS

Tumor pathologies included meningioma (16 patients), epidermoid cyst (2), trigeminal schwannoma (2), invasive pituitary adenoma (1), and chondrosarcoma (1). Mean (range) preoperative tumor size was 4.0 cm (1.3-9). Mean (range) length of follow-up was 4 years (range 0.1-10). Overall tumor control and gross total resection were achieved in 95 and 23% of patients, respectively. Lateral sphenoidectomy was performed in 16 patients (73%) for enhanced surgical access and/or tumor extension to the infratemporal fossa (6 patients). Postoperatively, cranial nerve deficits occurred in 12 (55%) patients (V-9 patients; III, IV, or VI-4; VII-2; VIII-2). Cerebrospinal fluid leak and hydrocephalus occurred in two and four patients, respectively.

CONCLUSION

In combination with middle fossa-based approaches to tumors involving MC and CS, lateral sphenoidectomy may play a viable role in tumor access and control.

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.

An Alternative Endoscopic Anterolateral Route to Meckel's Cave: An Anatomic Feasibility Study Using a Sublabial Transmaxillary Approach

OBJECTIVE

To describe an endoscopic anterolateral surgical route to the lateral portion of Meckel's cave.

METHODS

A sublabial transmaxillary transpterygoid approach was performed in 6 cadaveric heads (12 sides). A craniectomy was drilled between the foramen rotundum (FR) and foramen ovale (FO) with defined borders. Extradural dissection was performed up to the V2-V3 junction of the trigeminal ganglion. The working space was analyzed using anatomic measurements.

RESULTS

The approach allowed for extradural dissection to the lateral aspect of Meckel's cave and provided excellent exposure of V2, V3, and the V2-V3 junction at the gasserian ganglion. The mean distance between the FR and FO along the pterygoid process of the sphenoid bone was 21.3 ± 2.8 mm (range, 18-24.4 mm). The mean distance of V2 and V3 segments from their foramina to the gasserian ganglion junction was 12.0 ± 2.3 mm (range, 9.2-14.6 mm) and 15.2 ± 2.7 mm (range, 12.3-18.5 mm), respectively (6 sides). A potential working area (mean area, 89 mm²) is described. Its superior edge is from the FR to the V2-V3 junction at the gasserian ganglion, its inferior edge is from the FO to the V2-V3 junction at the gasserian ganglion, and its base is from the FO to the FR. The surgical anatomy of the infratemporal fossa, pterygopalatine fossa, and lateral Meckel's cave is highlighted.

CONCLUSIONS

An endoscopic anterolateral sublabial transmaxillary transpterygoid approach between the FR and FO avoids crossing critical neurovascular structures within the cavernous sinus and pterygopalatine fossa and can provide a safe surgical corridor for laterally based lesions in Meckel's cave.

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.

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.

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.

Morbid obesity increases risk of morbidity and reoperation in resection of benign cranial nerve neoplasms

OBJECTIVE

Obesity has been associated with increased risk for postoperative CSF leak in patients with benign cranial nerve tumors. Other measures of postoperative morbidity associated with obesity have not been well characterized.

METHODS

Patients enrolled in the American College of Surgeons' National Surgical Quality Improvement Program (ACS-NSQIP) from 2007 to 2013 with a diagnosis code of a benign neoplasm of a cranial nerve were included. The primary outcome of postoperative morbidity was analyzed as well as secondary outcomes of readmission and reoperation. The main covariate of interest was body mass index (BMI).

RESULTS

A total of 561 patients underwent surgery for a benign cranial nerve neoplasm between 2007 and 2013. Readmission data, available for 2012-2013(n=353), revealed hydrocephalus, facial nerve injury, or CSF leak requiring readmission or reoperation occurred in 0.85%, 1.42%, and 3.12%, respectively. Composite morbidity included wound complications, infection, respiratory insufficiency, transfusion requirement, stroke, venous thromboembolism, coma and cardiac arrest. On multivariable analysis patients with class I (BMI 30-34.9) and II (BMI 35-39.9) obesity showed trends towards increasing return to operating room, though not significant, but there was no trend for composite complications in class I and II obesity patients. However, class III obesity, BMI≥40, was associated with increased odds of composite morbidity (OR 4.40, 95% CI 1.24-15.88) and return to the operating room (OR 5.97, 95% CI 1.20-29.6) relative to patients with a normal BMI, 18.5-25.

CONCLUSIONS

Obesity is an independent and important risk factor for composite morbidity in resection of benign cranial nerve neoplasms, and as such, merits discussion during preoperative counseling.

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.