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)

Abstract

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.

Surgical Management of Craniovertebral Junction Schwannomas: A Systematic Review

“…The main therapeutic goals consist in providing clinical improvement and local tumor control, while minimizing complication risks and quality-of-life impairment [ 59 , 60 , 61 ]. Microsurgical tumor resection represents the current mainstay treatment, by allowing decompression of the CVJ neuro-vascular structures and prompt symptomatic relief.…”

“…Similarly, micro-Doppler assistance may minimize the risk of vascular injuries in case of tumors encasing arterial and venous structures of the posterior circulation [ 10 ]. Although modern surgical management is shifting towards less aggressive procedures and PTR [ 59 ], most of our pooled cases received GTR, suggesting that accurate treatment planning and approach selection optimize safe tumor exposure and neuro-vascular control, with achievable maximal resection. No standardized guidelines on extent of surgical resection currently exist, but several authors suggested to pre-operatively plan PTR or GTR on a case-by-case basis [ 59 ].…”

“…Although modern surgical management is shifting towards less aggressive procedures and PTR [ 59 ], most of our pooled cases received GTR, suggesting that accurate treatment planning and approach selection optimize safe tumor exposure and neuro-vascular control, with achievable maximal resection. No standardized guidelines on extent of surgical resection currently exist, but several authors suggested to pre-operatively plan PTR or GTR on a case-by-case basis [ 59 ]. As the surgical goal is to provide symptomatic relief and prevent the onset of tumor recurrence, while minimizing the risk of surgical complications, GTR should be planned only for tumors not encasing the vascular nor neural structures, especially if they have a clear surgical plane against the adjacent cranial nerves.…”

“…As the surgical goal is to provide symptomatic relief and prevent the onset of tumor recurrence, while minimizing the risk of surgical complications, GTR should be planned only for tumors not encasing the vascular nor neural structures, especially if they have a clear surgical plane against the adjacent cranial nerves. Contrarily, in case of lesions invading or encasing critical neurovascular structures, where safe tumor removal is not pursuable, maximal PTR should be devised with the preservation of neurovascular structures infiltrated by the disease [ 59 ].…”

“…Although SRS has been accepted and regulated for vestibular schwannomas [ 3 ], only a few studies on CVJ schwannomas have been published, with limited information to devise standardized guidelines [ 59 ]. The largest-to-date multicenter studies from Hasegawa et al [ 68 ] and Kano et al [ 69 ] reported the use of upfront SRS for small non-dumbbell jugular foramen schwannomas and adjuvant STS for post-surgery residual tumors, showing variable rates of local tumor control, symptom relief, and cranial neuropathy improvement, but it somewhat risks radiation-induced adverse events.…”