Surgical management of trigeminal neuromas: a report of eight cases

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.

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.

Mini-invasive surgery of infratemporal fossa schwannomas

Background:

Infratemporal fossa schwannomas are benign, encapsulated tumours of the trigeminal nerve limited to the infratemporal fossa. Because of the complications and significant morbidity associated with traditional surgical approaches to the infratemporal fossa, which include facial nerve dysfunction, hearing loss, dental malocclusion and cosmetic problems, less invasive alternatives have been sought.

Methods:

This paper reports two cases of infratemporal fossa schwannomas treated in 2012 using mini-invasive approaches. The literature regarding different infratemporal fossa approaches was reviewed.

Results:

The first schwannoma was 30 mm in size and was removed completely by a preauricular subtemporal approach. The second one was 25 mm in size and was removed completely using a purely transnasal endoscopic approach. In both cases, there were no intra-operative or post-operative complications.

Conclusion:

These two approaches allow non-invasive and wide exposure of the infratemporal fossa as compared to classical approaches. Surgical approach should be selected according to the tumour's anatomical location with respect to the maxillary sinus posterior wall. The preauricular subtemporal approach is recommended for tumours localised posterolaterally with respect to the maxillary sinus posterior wall. Medial and anterior tumours near the maxillary sinus posterior wall can be best removed using a transnasal endoscopic approach.

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.

Endoscopic endonasal management of trigeminal schwannomas extending into the infratemporal fossa

Extracranial trigeminal schwannomas extending into the infratemporal fossa are rare. The traditional surgical approaches to the infratemporal fossa are associated with complications, such as facial nerve dysfunction, hearing loss, dental malocclusion and cosmetic problems. We report eight patients (four males, four females, age range=31-62 years) who were treated between 2004 and 2009 for extracranial trigeminal schwannomas extending into the infratemporal fossa. Schwannomas were surgically removed using a purely endoscopic endonasal approach. The maximum diameters of the tumours ranged from 30 mm to 70 mm and all tumours were completely removed. There were no intraoperative or postoperative complications in this series. There were no recurrences during the follow-up period which ranged from 10 to 74 months (mean=30 months). The purely endoscopic endonasal approach may provide a minimally invasive and safe approach to remove extracranial trigeminal schwannomas extending into the infratemporal fossa. Radical resection was associated with an excellent long-term outcome in this series.

Stereotactic radiosurgery for trigeminal schwannomas

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Stereotactic Radiosurgery of Cranial Nonvestibular Schwannomas: Results of Single- and Multisession Radiosurgery

BACKGROUND:

Surgical resection of nonvestibular cranial schwannomas carries a considerable risk of postoperative complications. Stereotactic radiosurgery (SRS) offers a non-invasive treatment alternative. The efficacy and safety of multi-session SRS of nonvestibular cranial schwannomas has not been well studied.

OBJECTIVE:

To analyze the results of single- and multi-session SRS of nonvestibular cranial schwannomas.

METHODS:

From 2001 to 2007, 42 lesions in 40 patients were treated with SRS at Stanford University Medical Center, targeting schwannomas of cranial nerves IV (n = 1), V (n = 18), VII (n = 6), X (n = 5), XII (n = 2), jugular foramen (n = 8), and cavernous sinus (n = 2). SRS was delivered to a median marginal dose of 18 Gy (range, 15-33 Gy) in 1 to 3 sessions, targeting a median tumor volume of 3.2 cm3 (range, 0.1-23.7 cm3). The median doses for treatments in 1 (n = 18), 2 (n = 9), and 3 (n = 15) sessions were 17.5, 20, and 18 Gy, respectively.

RESULTS:

With a median follow-up of 29 months (range, 6-84 months), tumor control was achieved in 41 of the 42 lesions. Eighteen of 42 lesions (43%) decreased in size; 23 tumors (55%) remained stable. There were 2 cases of new or worsening cranial nerve deficits in patients treated in single session; no patient treated with multi-session SRS experienced any cranial nerve toxicity (P = 0.18).

CONCLUSION:

SRS of nonvestibular cranial schwannomas provides excellent tumor control with minimal risk of complications. There was a trend towards decreased complications with multi-session SRS.