Neurilemomas of the trigeminal nerve

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

OBJECTIVE

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

METHOD

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

RESULTS

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

CONCLUSION

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

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

BACKGROUND AND OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

BACKGROUND AND OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

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

INTRODUCTION AND IMPORTANCE

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

PRESENTATION OF CASE

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

CLINICAL DISCUSSION

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

CONCLUSION

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

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.

Orbital schwannoma management: a case report, literature review, and potential paradigm shift

PURPOSE

To present a case of orbital schwannoma and assess the literature on treatment modalities.

METHODS

A MEDLINE literature search for cases of orbital schwannomas was performed using the PubMed search tool using the search terms "orbital schwannoma" and "orbital neurilemmoma." Papers were included if they were peer-reviewed, published in English, discussed management, and included the search terms. Each article was rated using the scale developed by the British Centre for Evidence-Based Medicine. In addition, we present a case report of an orbital schwannoma.

RESULTS

A total of 428 articles were found. 102 met the criteria for inclusion. Only two articles met Level 1 evidence and 16 were important to the clinical care process. We report a case of a biopsy-proven orbital schwannoma managed conservatively with observation over a 4-year period due to risk of cosmetic disfigurement with tumor removal. There has been no change in tumor size and no associated complications during follow up.

CONCLUSIONS

There is a paucity of data on the natural history of orbital schwannomas. Based on our review of the literature, we recommend observation for asymptomatic or minimally symptomatic orbital schwannomas with minimal growth over an extended period of time. For rapidly growing tumors or large tumors affecting key structures causing visual loss, diplopia, aesthetic disfigurement, or patient discomfort, a more aggressive approach may be necessary.

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.

Surgical Management of Multifocal Trigeminal Schwannomas

BACKGROUND

Isolated trigeminal schwannomas occur in 0.07% to 0.3% of intracranial tumors and account for 0.8% to 8% of intracranial schwannomas and 1/3 of Meckel cave tumors. The presence of multisegmental schwannoma is rare, resulting in a limited understanding of its optimal management.

OBJECTIVE

To describe potential surgical options to manage this rare entity.

METHODS

A 2-institution retrospective review of all patients with pathologically confirmed trigeminal schwannoma managed with resection from January 2009 through January 2019 was conducted. A manual chart review was performed to verify patients' inclusion and collect data about age, sex, tumor size, tumor site, treatment modality, surgical approach, complications, and follow-up duration and status.

RESULTS

A total of 4 patients (age range 12-50 yr) who underwent a variety of cranial and orbitocranial approaches for tumor resection were identified. Patients achieved good outcomes with improvement of visual outcomes. One case of infection and 1 case of partial tumor recurrence requiring reresection were identified.

CONCLUSION

Multisegmental trigeminal schwannoma is a rare and unique entity, often associated with trigeminal schwannomatosis. Interdisciplinary management has been shown to be the most effective method for improving patient outcomes with these complex and poorly understood diseases.

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.

A Case of Trigeminal Schwannoma Presenting as a Parasellar Mass

Schwannoma's of considerable size arising from the trigeminal nerve are very rare. Here, a case of a large right-sided parasellar mass diagnosed as a trigeminal schwannoma is reported. Complete resection of the tumor was successfully achieved. The patient had an excellent postoperative course.

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.

Radiosurgery for Secondary Trigeminal Neuralgia: Revisiting the Treatment Paradigm

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Lateral orbitotomy for a maxillary nerve schwannoma: case report

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

Lumbar Herniated Disk Mimicking Neurinoma

A case of huge foraminal herniated nucleus pulposus is reported, with scalloping of the vertebral body, mimicking neurinoma on CT and MR images.

Multimodality Management of Trigeminal Schwannomas

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

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

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

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

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

Intracranial trigeminal schwannoma

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

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

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

Surgical management of trigeminal schwannomas: defining the role for endoscopic endonasal approaches

OBJECT

Because multiple anatomical compartments are involved, the surgical management of trigeminal schwannomas requires a spectrum of cranial base approaches. The endoscopic endonasal approach to Meckel's cave provides a minimal access corridor for surgery, but few reports have assessed outcomes of the procedure or provided guidelines for case selection.

METHODS

A prospectively acquired database of 680 endoscopic endonasal cases was queried for trigeminal schwannoma cases. Clinical charts, radiographic images, and long-term outcomes were reviewed to determine outcome and success in removing tumor from each compartment traversed by the trigeminal nerve.

RESULTS

Four patients had undergone endoscopic resection of trigeminal schwannomas via the transpterygoid approach (mean follow-up 37 months). All patients had disease within Meckel's cave, and 1 patient had extension into the posterior fossa. Gross-total resection was achieved in 3 patients whose tumors were purely extracranial. One patient with combined Meckel's cave and posterior fossa tumor had complete resection of the extracranial disease and 52% resection of the posterior fossa disease. One patient with posterior fossa disease experienced a sixth cranial nerve palsy in addition to a corneal keratopathy from worsened trigeminal neuropathy. There were no CSF leaks. Over the course of the study, 1 patient with subtotal resection required subsequent stereotactic radiosurgery for disease progression within the posterior fossa.

CONCLUSIONS

Endoscopic endonasal approaches appear to be well suited for trigeminal schwannomas restricted to Meckel's cave and/or extracranial segments of the nerve. Lateral transcranial skull base approaches should be considered for patients with posterior fossa disease. Further multiinstitutional studies will be necessary for adequate power to help determine relative indications between endoscopic and transcranial skull base approaches.

Endoscopic Endonasal Resection of Trigeminal Schwannomas

The surgical management of trigeminal schwannomas (TNs) entails the use of a variety of cranial base approaches for their effective surgical management. Although an extended middle fossa or posterior petrosal approach may be more appropriate for disease with primarily posterior fossa involvement, the expanded endoscopic approaches are suited for tumors with predominately middle fossa and/or extracranial involvement along the V2 and V3 divisions and limited posterior fossa extension. The endoscopic endonasal resection of TNs within the middle fossa, pterygopalatine fossa, and infratemporal fossa is reviewed in this article with a brief discussion of reported outcomes.

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

Background

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

Methods

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

Results

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

Conclusion

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

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

BACKGROUND:

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

OBJECTIVE:

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

METHODS:

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

RESULTS:

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

CONCLUSION:

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Stereotactic Radiotherapy for Trigeminal Schwannomas

BACKGROUND:

Data on radiotherapy for trigeminal schwannomas (TSs) and comparison of stereotactic radiosurgery (SRS) with fractionated stereotactic radiotherapy (FSRT) are limited.

OBJECTIVE:

We present a large retrospective review of our institutional experience treating TSs with SRS and FSRT. We also describe a flare phenomenon experienced by some patients.

METHODS:

The records of 23 consecutive TSs patients treated with radiotherapy between 1996 and 2011 were reviewed. We investigated radiographic response, tumor control, and toxicity.

RESULTS:

Ten patients underwent SRS and 13 underwent FSRT, with median clinical follow-up of 32 months (range, 3–120 months). Tumor control at 5 and 10 years was 94% overall. Symptom control at 5 years was achieved in 48% of all patients, with nonsignificant improvement in more patients in the FSRT group than those in the SRS group (56% vs 40%, P = .37). Acute toxicity was higher in the FSRT group (38.5 vs 0%, P &lt; .01), although lesions treated with FSRT were larger (mean, 9.5 mL vs 4.8 mL, P &lt; .01). A symptomatic flare phenomenon occurred in 2 patients (8.7% overall) during FSRT, involving transient cystic formation and dramatic size increase. One lesion regressed in size and 1 remained stable on follow-up.

CONCLUSION:

Tumor control rates for TSs are excellent with SRS and FSRT with minimal toxicity. This represents the first documented report of a flare phenomenon after FSRT for TS treatment. Flare risk after FSRT in previously resected large lesions should be discussed with patients before treatment, and prophylactic oral steroids may be considered.

Combined craniofacial approach for the removal of a large trigeminal schwannoma invading the infratemporal fossa

BACKGROUND

Trigeminal schwannomas are rare tumours accounting for 0.07-0.36% of all intracranial tumours and 0.8-8% of intracranial schwannomas. Symptoms and signs of these lesions depend on the site of the tumour, which may compress the nerve of origin or adjacent nerves.

CASE REPORT

We describe a case of a 69-year-old woman with a history of progressively worsening hypoesthesia involving the third division of the trigeminal nerve. A tumour of 5-cm diameter was revealed within the right cranial middle fossa, extending to the lateral wall of the cavernous sinus, the infratemporal fossa and the posterior wall of the maxillary sinus. A combined craniofacial approach was undertaken. A right extended subtemporal craniotomy was performed. The intracranial component of the tumour, originating from the third division of the trigeminal nerve and compressing the cavernous sinus, was removed in total. We proceeded with a Weber-Ferguson approach through which the extracranial component of the tumour was also totally resected. The postoperative computed tomography of the head has shown complete tumour removal. The histopathologic examination revealed a cellular neurinoma. Postoperatively, the patient expressed a transitory palsy of the oculomotor nerve, which resolved within a few weeks. The patient remains free of recurrence with mild hypoesthesia of the third trigeminal branch 5 years after treatment.

DISCUSSION

Surgery of trigeminal schwannomas may be a very challenging task. Various surgical approaches for trigeminal schwannomas excision have been described. With this combined approach, the tumour was freed from the surrounding tissues and was easily and totally removed.

Trigeminal Schwannomas: Skull Base Approaches and Operative Results in 105 Patients

BACKGROUND:

Trigeminal schwannomas make up 0.8% to 8% of all intracranial schwannomas.

OBJECTIVE:

To analyze our surgical experience with trigeminal schwannomas.

METHODS:

We performed 107 operations on 105 patients harboring trigeminal schwannomas over the past 30 years. We classified the tumors as peripheral, ganglion cavernous, posterior fossa root, and dumbbell types according to the portion of the nerve that gave rise to the tumor.

RESULTS:

Fourteen were peripheral-type tumors (13.1%), 39 (36.4%) were ganglion cavernous type, 22 (20.6%) were posterior fossa root type, and 32 (30.0%) were dumbbell type. Sixty-five tumors were solid, 35 were mixed, and only 7 were cystic. Among solid tumors, 14 were vascular, fibrous, and adherent to adjacent structures. Total or near-total removal was performed in 86 cases (81.9%), and subtotal removal was achieved in 18 (17.1%). The most common symptom was facial hypesthesia, occurring in 69 patients. This symptom improved in 11 patients, persisted in 50 patients, and worsened in 8 patients after surgery. New postoperative hypesthesia was observed in 8 patients. The second most common symptom was facial pain, observed in 24 patients. Facial pain subsided in 22 and persisted in 2 patients after surgery. Diplopia was observed in 21 patients. This symptom improved postoperatively in 14 patients, persisted in 6 patients, and worsened in 1 patient.

CONCLUSION:

The present series demonstrates acceptable results using microsurgical treatment to remove trigeminal schwannomas. Pain and diplopia may be relieved after surgery; however, hypesthesia frequently remains or may be worsened by surgery.

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

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

Sphenocavernous and infratemporal trigeminal neurinomas: surgical series of 15 cases

A consecutive series of 15 patients with trigeminal schwannomas treated surgically at the Centre Medico-Chirurgical Foch between 1979 and 1985 is reported. This report is limited to sphenocavernous (nine cases) and infratemporal (six cases) tumors. Initial clinical symptoms of these cases are detailed, including trigeminal and abducens nerve signs. Preoperative selective angiography and embolization are important adjuncts to surgical management. The surgical approach depends on the anatomic location of the tumor. Sphenocavernous neurinomas were removed through a pterionosubtemporal approach. Occasionally, infratemporal neurinomas were approached in two stages because of the need to reconstruct the skull base and prevent postoperative cerebrospinal fluid rhinorrhea. There were no operative deaths in the series and complete extirpation was achieved in all but one case.

Linear Accelerator Radiosurgery for Nonvestibular Schwannomas

BACKGROUND:

Nonvestibular schwannomas are uncommon tumors of the brain often treated by surgical resection. Surgery may be associated with high morbidity.

OBJECTIVE:

We present a series of nonvestibular schwannomas treated with linear accelerator radiosurgery during a 19-year period.

METHODS:

This is a retrospective analysis of patients who underwent treatment of nonvestibular schwannomas at the University of Florida with linear accelerator radiosurgery between August 1989 and February 2008. Forty-nine patients underwent treatment during the study period, and 6 were lost to follow up. The mean age was 51 years (range, 17-82 years), 39% had previous surgical resection, and 67% presented with preradiosurgery cranial nerve deficits. There were 25 trigeminal, 18 jugular foramen, 2 facial, 2 oculomotor, 1 hypoglossal, and 1 high cervical schwannomas. The median tumor volume was 5.3 mL (range, 0.3-24.5 mL), treated with a median dose of 1250 cGy (range, 1000-1500 cGy). Study endpoints were actuarial local tumor control and neurological outcome.

RESULTS:

Forty-three patients were available for a median follow-up of 37 months (range, 6-210 months). Actuarial local tumor control was 97% at 1 year, 91% at 4.5 years, and 83% at 5 years. There were 4 new cranial nerve deficits (9%) including facial numbness (2 patients), anesthesia dolorosa (1 patient), and facial weakness (1 patient). Thirty-nine percent had documented clinical and/or symptomatic improvement. There were no other morbidity and no mortality with treatment.

CONCLUSION:

Radiosurgery for nonvestibular schwannomas offers good actuarial local tumor control and has superior morbidity compared with surgical resection. This is the largest linear accelerator radiosurgical series, and the second largest radiosurgical series reported to date.

Trigeminal schwannomas: experience with 57 cases and a review of the literature

Trigeminal schwannoma is a mostly benign tumor that can be cured by complete resection. Over the last few decades, several pioneers have developed surgical approaches enabling the total removal of such tumors. We analyzed 57 patients who underwent radical surgery, including 45 patients who underwent skull base surgery as their initial treatment, for removal of trigeminal schwannomas. Here, we report the surgical management of these cases. Since 1990, all such patients have been treated using three main types of middle fossa skull base approaches, which minimize the exposure of the brain: the anterior transpetrosal approach, subtemporal interdural approach (Dolenc), or a combination of these approaches. Before 1990, total tumor removal was achieved in only three of eight patients (38%). After 1990, the tumors were totally removed in 43 patients (90%) and were nearly completely removed in an additional three patients (6%). Among the patients who underwent skull base surgery as their initial treatment, a complete resection was achieved in 93% (42/45 patients) of the cases. However, total surgical removal after surgery and Gamma knife surgery was very difficult because of dense adhesions to the brain stem and cranial nerves. No surgery-related mortalities occurred in this series, and the individual KPS scores were more than 90% among the patients who underwent skull base surgery. No recurrences requiring additional surgery have occurred after an average follow-up period of 4.9 years. Most of the trigeminal schwannomas could be removed totally and safely during a single operation after the introduction of skull base surgery. Therefore, radiosurgery should not be applied as the treatment of first choice for younger patients. A correct anatomical knowledge is critical for minimizing brain exposure and avoiding surgical complications.

Dural relationships of Meckel cave and lateral wall of the cavernous sinus

OBJECT

The purpose of this study was to elucidate the anatomy of the trigeminal nerve (cranial nerve [CN] V), Meckel cave (MC), and lateral wall of the cavernous sinus (CS).

METHODS

Ten fresh cadaver heads (20 sides) and 2 middle fossa embalmed specimens were removed, decalcified, sectioned, stained, and studied microscopically.

RESULTS

In the MC, the posterior fossa meningeal dura extended into the middle fossa surrounding CN V. The average medial length of the MC was 16.7 mm and the lateral length was 13.5 mm. The dural roof of MC was thicker than its floor and was covered by a paw-shaped fibrous tissue extending from the tentorium to the ganglion (in 100% of specimens). Between the dural sleeve of the MC and venous space of the CS, a separate fibrous wall could be identified in 45% (9 of 20) extending between the tentorium and the floor of the CS. The mean length of CN V in the MC proximal to the posterior margin of the Gasserian ganglion was 11.8 mm. The mean length of CN V1 was 19.4 mm; V2, 12.3 mm; and V3, 7.4 mm distal to the anterior margin of the ganglion. The periosteal dura followed the bone of the middle fossa and was continuous with the extracranial periosteum. The lateral dural wall of the CS consisted of a medial (membranous) and a lateral wall. The latter was separated into a thin outer layer and a thicker fibrous inner layer that became thinner as it extended posterolaterally.

CONCLUSIONS

The MC is an extension of the posterior fossa dura with intricate relationships with the surrounding dural layers.

Surgical management of trigeminal schwannomas

OBJECT

The authors provide a detailed review of the surgical management of trigeminal schwannomas (TSs) and also discuss the best surgical approach based on the surgical anatomy and tumor extension.

METHODS

A series of 17 patients with TSs who were surgically treated between 1987 and 2008 at the authors' institution is reported. The lesions were small (< 3 cm) in 2, medium (between 3 and 4 cm) in 5, large (> 4 cm) in 6, and giant (> 5 cm) in 4 cases. Preoperative symptoms included trigeminal hypesthesia (53%), facial pain (53%), headaches (35.3%), hearing impairment (17.6%), seizures (17.6%), diplopia (11.8%), ataxia (11.8%), and hemiparesis and increased intracranial pressure with papilledema (5.9%). The mean follow-up duration was 10.5 years (121.6 months), with an average of 0.8 patients per year.

RESULTS

Total tumor excision was possible in 16 patients, with no surgery-related deaths. Postoperative trigeminal anesthesia was observed in 7; trigeminal motor function was preserved in 7. Two developed cerebrospinal fluid leakage, 2 presented with mild facial palsy, and 1 patient with neurofibromatosis Type 2 had recurrence of the tumor, which was uneventfully removed. Of the 9 who reported facial pain, only 1 remained symptomatic postoperatively.

CONCLUSIONS

The best treatment for TSs is complete microsurgical removal. Postoperative preservation of trigeminal nerve function is possible when resection of the lesion is performed at well-established skull base neurosurgical centers. Although good results have been reported with radiosurgery, no cure can be obtained with this therapeutic modality. Instead, this treatment should be reserved only for nonresectable and residual tumors within the cavernous sinus.

Stereotactic radiosurgery for trigeminal schwannoma: tumor control and functional preservation Clinical article

OBJECT

To evaluate outcome predictors after stereotactic radiosurgery (SRS) in patients with trigeminal schwannomas, the authors compared tumor control, functional preservation, and complications with tumor grade, tumor volume, patient age, and tumor imaging characteristics.

METHODS

The records of 33 consecutive patients with trigeminal schwannoma treated via Gamma Knife surgery were retrospectively reviewed. The median patient age was 49.5 years (range 15.1-82.5 years). Eleven patients had undergone prior tumor resection. Two patients had neurofibromatosis Type 2. Lesions were classified as root type (6 tumors), ganglion type (17 tumors), and dumbbell type (10 tumors) based on their location. The median radiosurgery target volume was 4.2 cm3 (range 0.5-18.0 cm3), and the median dose to the tumor margin was 15.0 Gy (range 12-20 Gy).

RESULTS

At an average of 6 years (range 7.2-147.9 months), the rate of progression-free survival (PFS) at 1, 5, and 10 years after SRS was 97.0, 82.0, and 82.0%, respectively. Factors associated with improved PFS included female sex, smaller tumor volume, and a root or ganglion tumor type. Neurological symptoms or signs improved in 11 (33.3%) of 33 patients and were unchanged in 19 (57.6%). Three patients (9.1%) had symptomatic disease progression. Patients who had not undergone a prior tumor resection were significantly more likely to show improvement in neurological symptoms or signs.

CONCLUSIONS

Stereotactic radiosurgery is an effective and minimally invasive management option in patients with residual or newly diagnosed trigeminal schwannomas. Predictors of a better treatment response included female sex, smaller tumor volume, root or ganglion tumor type, and the application of SRS as the primary treatment.

Surgical management of giant trigeminal schwannomas extending into the parapharyngeal space

PURPOSE

Trigeminal schwannomas extending into the deep parapharyngeal space are relatively rare, and a surgical approach to such tumors has not been well established. We report four cases in which the tumors were completely removed by using a combination of three approaches.

METHODS

Four patients with trigeminal schwannomas extending into the extracranial space were surgically treated using a combination of the transcervical approach, anterolateral retromaxillar pathway via gingivobuccal sulcus, and epi and interdural middle fossa approach.

RESULTS

The maximum diameters of the tumors ranged from 4 to 7 cm. Three tumors extended beyond the lower end of the maxillary sinus. All tumors were completely excised. The Karnofsky performance scales after surgery were more than 90% in all patients.

CONCLUSION

Although the tumors extending to the deep parapharyngeal space are difficult to completely remove via a single approach, a combined approach is useful in these huge extracranial extensions.

CYBERKNIFE RADIOSURGERY FOR TRIGEMINAL SCHWANNOMAS

OBJECTIVE

Trigeminal schwannomas (TS) are benign tumors that are managed by surgical resection and/or stereotactic radiosurgery. Most radiosurgical series report results using the gamma knife. The CyberKnife (Accuray, Inc., Sunnyvale, CA) is a frameless, robotic stereotactic radiosurgical system. In this series, we report our experience using the CyberKnife in the treatment of TS.

METHODS

We retrospectively reviewed the medical records and diagnostic imaging in 13 consecutive patients with TS who were treated with the CyberKnife from 2003 to 2007. Seven patients had a previous surgical resection. The mean tumor volume was 6.3 mL (range, 0.39–19.98 mL), and the mean marginal dose was 18.5 Gy. Six of the tumors were treated in a single session. The mean clinical follow-up period was 21.8 months (range, 7–53 months).

RESULTS

In this series, the tumor control rate was 100%. The average reduction in tumor volume was 45% (range, 14–98%). A modest improvement in facial pain was noted in 4 of the 6 patients who presented with this symptom. One patient had improvement in facial numbness, and another had improvement in pretreatment headaches. One patient developed jaw weakness and facial dysesthesia, and another patient developed asymptomatic radiation necrosis.

CONCLUSION

Although the length of follow-up is limited, we report our initial experience with CyberKnife treatment of TS. Our results demonstrate tumor control rates and clinical outcomes that parallel those of previous reports using gamma knife radiosurgery; however, long-term follow-up studies are needed.

Multicompartmental trigeminal schwannoma--a clinical report

Trigeminal schwannomas are rare, benign tumors. The unique course of the trigeminal nerve allows these tumors to grow into various intracranial compartments. Multicompartmental tumors are infrequent and may present a formidable challenge to the surgeon. Liaison between a neurosurgeon and a craniofacial surgeon ensures optimal surgical outcome. We report one such patient. The tumor was approached via a modified frontotemporal craniotomy with orbitozygomatic osteotomy. It was completely extradural and could be totally excised with minimal morbidity.

Giant tumour of the pterygopalatine fossa

Neurilemmomas are benign and slow growing tumours. Neurilemmomas of the pterygopalatine fossa are rare. In this paper we present a case of schwannoma arising in the pterygopalatine fossa with extension into infratemporal fossa and floor of the orbit. A transantral approach was used for excision of the tumor following which the defect in the floor of the orbit was reconstructed with the help of a temporoparietal flap.

Trigeminal schwannomas: experience with 68 cases

Trigeminal schwannomas (TS) are rare. Only a couple of series involving a large number of cases have been reported. In the present study we aimed to analyse the clinical characteristics of TS, the surgical approaches used to treat TS, and the outcomes for patients undergoing surgical treatment for TS via retrospective analysis of departmental records. Data for 68 patients treated for TS in the Department of Neurosurgery at the All India Institute of Medical Sciences between January 1993 and December 2005 were analysed. Most patients were in the fourth decade of life, with the duration of symptoms ranging from 1 month to 13 years. Twenty-nine TSs were classified as type A, 13 as type B and 26 as type C, depending upon size. A skull base approach was used in every surgically treated case. Of the 46 patients for whom radiological follow-up data were available, complete tumour excision was achieved in 35 cases (76%). Follow-up ranged from 3 months to 12 years (mean 62 months). One patient died and nine (15%) had permanent morbidity in the form of corneal opacity (5) or facial (2) or trochlear (2) nerve palsy. We conclude that trigeminal neuromas are best treated by total surgical resection, which yields acceptable results with low rates of mortality and permanent morbidity.

Evolution in the assessment and management of trigeminal schwannoma

EDUCATIONAL OBJECTIVE

At the conclusion of this presentation, the participants should be able to understand the contemporary assessment and management algorithm used in the evaluation and care of patients with trigeminal schwannomas.

OBJECTIVES

1) Describe the contemporary neuroradiographic studies for the assessment of trigeminal schwannoma; 2) review the complex skull base osteology involved with these lesions; and 3) describe a contemporary management algorithm.

STUDY DESIGN

Retrospective review of 23 cases.

METHODS

Chart review.

RESULTS

From 1984 to 2006, of 23 patients with trigeminal schwannoma (10 males and 13 females, ages 14-77 years), 15 patients underwent combined transpetrosal extirpation, 5 patients underwent stereotactic radiation, and 3 were followed without intervention. Of the 15 who underwent surgery, total tumor removal was achieved in 9 patients. Cytoreductive surgery was performed in six patients; of these, four received postoperative radiation. One patient who underwent primary radiation therapy required subsequent surgery. There were no deaths in this series. Cranial neuropathies were present in 14 patients pretreatment and observed in 17 patients posttreatment. Major complications included meningitis (1), cerebrospinal fluid leakage (2), major venous occlusion (1), and temporal lobe infarction (1).

CONCLUSIONS

Trigeminal schwannomas are uncommon lesions of the skull base that may occur in the middle fossa, posterior fossa, or both. Moreover, caudal extension results in their presentation in the infratemporal fossa. Contemporary diagnostic imaging, coupled with selective use of both surgery and radiation will limit morbidity and allow for the safe and prudent management of this uncommon lesion.

Current concepts in management of meningiomas and schwannomas

Meningiomas and schwannomas are the two most common extra-axial intracranial tumors in adults. Since their initial discovery, these often-benign lesions have shared a parallel metamorphosis in their management. The goal of this article is to provide a review of the current literature surrounding the mainstays of therapy for these lesions.