2026-06-05
Schwannomas — also referred to as neurilemmomas — are benign peripheral nerve sheath tumors. They arise from any nerve covered by a Schwann cell sheath. Schwannomas account for 25–45% of head and neck tumors. Approximately 4% of head and neck schwannomas present as sinonasal schwannomas. Brachial plexus schwannomas account for only about 5% of all schwannomas. Vagal schwannomas of the neck represent approximately 2–5% of all neurogenic tumors.
Although head and neck schwannomas are uncommon, they should be included in the differential diagnosis of any unilateral, slowly growing mass in the head and neck region in adults. Schwannomas have long posed a diagnostic challenge, as they are frequently asymptomatic for extended periods and histopathology remains the gold standard for diagnosis. Treatment is generally surgical and is determined by the location of the tumor and its nerve of origin. Their rarity, complex anatomical location, and risk of postoperative morbidity make them a considerable challenge for surgeons.
Treatment of Trigeminal Schwannoma
The management of trigeminal schwannoma encompasses clinical and MRI-based surveillance, surgical resection, and radiotherapy or radiosurgery. Microsurgical techniques have reduced the morbidity associated with trigeminal schwannoma surgery, but the risk of complications — including cranial nerve palsy and CSF leak — continues to represent a meaningful challenge in the context of gross total resection (GTR). These tumors appear to progress following subtotal resection (STR). Accordingly, for patients in this situation, or for those who are not suitable candidates for resection in general, radiotherapy may be considered a reasonable alternative to repeat surgery. We consider this modality most appropriate for small, unresectable schwannomas confined to the cavernous sinus, or for residual tumor following surgery. In our series, the median tumor volume was 8.05 cm³ and the median maximum diameter was 3.20 cm. All patients in our cohort were symptomatic at presentation and harbored relatively large, space-occupying tumors. Following interdisciplinary tumor board discussion, primary surgical treatment was the preferred approach — also in order to obtain a definitive histopathological diagnosis, given that trigeminal schwannomas account for only 0.1–0.5% of all intracranial tumors. No incidentally discovered trigeminal schwannomas were encountered; all patients had experienced a decline in quality of life and presented with cranial nerve deficits. Given the tumor volumes and dimensions involved, primary radiotherapy for upfront tumor control was not considered necessary in the initial setting.
Stereotactic Radiosurgery and Fractionated Radiotherapy
Stereotactic radiosurgery and fractionated radiotherapy have been applied to patients with intracranial schwannomas of various origins. Mirroring the treatment philosophy for vestibular schwannomas, treatment decisions should be based on the anticipated morbidity and the likelihood of tumor control. For larger lesions, surgical resection followed by radiotherapy to address residual tumor is an appropriate strategy. Larger tumors or those causing brainstem compression should be managed primarily by surgery rather than radiosurgery. However, when surgery is contraindicated for larger lesions, satisfactory tumor control rates at 5 and 10 years have been achieved in 94% of trigeminal schwannoma patients treated with radiotherapy. It should be noted, however, that large cystic lesions treated with radiotherapy appear to carry an increased risk of transient enlargement and heightened toxicity.
For small vestibular schwannomas, radiotherapy achieves high tumor growth control rates at five years and beyond, with lower morbidity than surgery. Accordingly, for patients with smaller intracranial schwannomas — both vestibular and non-vestibular — fractionated radiotherapy and stereotactic radiosurgery represent viable alternatives to surgical resection. A retrospective analysis of patients with jugular foramen tumors treated with radiosurgery demonstrated lower cranial nerve morbidity compared with surgery; in patients without large tumors or symptomatic mass effect, radiosurgery was identified as the preferred treatment strategy. Both stereotactic radiosurgery and fractionated radiotherapy achieve high tumor control rates for trigeminal schwannomas with relatively limited morbidity and toxicity. Radiotherapy for trigeminal schwannoma resulted in functional improvement in 67.3% of patients, stable disease in 26.9%, and deterioration in only 2 patients (3.8%).
Radiotherapy in the Context of NF2
The role of radiotherapy for vestibular schwannomas in the setting of neurofibromatosis type 2 (NF2) is well established. NF2 patients present distinct management considerations, and the optimal treatment strategy — particularly for vestibular schwannomas — warrants specific discussion. It is now recognized that every treatment decision in NF2 requires a comprehensive, multidimensional assessment of all craniofacial and spinal disease sites to determine surgical priorities and overall strategy. Yao et al. have noted that for vestibular schwannomas in NF2, the preferred treatment is surgery combined with radiotherapy, contingent on institutional protocols. They also reported that the management of medium or small vestibular schwannomas may encompass watchful waiting, radiotherapy, and/or surgery, depending on patient preference or institutional standards. Their ultimate conclusion was that in the setting of NF2, the primary objective should be to preserve cranial nerve function for as long as possible, in conjunction with effective tumor control.
