Extracranial trigeminal schwannomas: A systematic review of surgical outcomes, anatomical distribution, and the evidence gap in radiotherapy.

Extracranial trigeminal schwannomas are rare benign nerve sheath tumors whose management remains challenging due to anatomical complexity and limited high-quality evidence. This systematic review characterized their clinical presentation, anatomical distribution, and treatment outcomes, and assessed the availability of radiotherapy data for purely extracranial lesions. The review followed PRISMA 2020 guidelines and was registered in PROSPERO (CRD420251276199). PubMed, Scopus, and Web of Science were searched from inception to January 2026; eligible studies were analyzed with respect to clinical features, anatomical location, treatment strategies, and outcomes. Twenty-five studies encompassing 65 patients were included, using the operational definition of purely extracranial disease applied in this review (lying entirely distal to the trigeminal ganglion and Meckel's cave without a dural-based or intracranial component). Surgery, mainly gross-total or near-total resection, was the most frequently reported strategy. As an exploratory, post hoc complement to the qualitative synthesis, and after excluding a non-decomposable, group-level-only cohort of 13 patients from the sensory-disturbance denominator, pooled proportions showed symptom or pain improvement in 97.8% of evaluable patients (44/45; 95% CI 88.4-99.6%), new or worsened postoperative sensory disturbance in 17.3% (9/52; 95% CI 9.4-29.7%), and recurrence in 1.6% (1/61; 95% CI 0.3-8.7%); these should be read as descriptive summaries of a heterogeneous literature rather than precise incidence estimates. Evidence derives exclusively from small, heterogeneous case reports and case series at moderate-to-high risk of bias, and no study provided extractable radiotherapy-specific outcomes for purely extracranial lesions. Comparative treatment effectiveness therefore remains unestablished, and this evidence gap highlights the need for standardized, multicenter reporting.