Enlargement of Multiple Branches of the Trigeminal Nerve in Non-Neoplastic Orbital Diseases: Review of MR Imaging in 14 Cases

Abstract

Background: Head and neck perineural disease is typically associated with cancer, but it can be associated with non-neoplastic conditions, especially IgG4-Related disease. Purpose: We present the MRI findings of trigeminal nerve involvement in 14 patients with 3 different types of non-neoplastic orbital disease. Material and Methods: A retrospective review of MR images of patients with enlargement of distinct TGN divisions who were evaluated in a neuro-ophthalmology clinic and were subsequently proved to have non-neoplastic orbital infiltrative or inflammatory diseases. Three experienced radiologists reviewed the MRI studies looking for extent and characteristics of perineural disease along the pathway of the 3 TGN divisions. Results: MRI demonstrated enhancement of at least one TGN division in 14 patients with bilateral or unilateral orbital infiltrative non-neoplastic conditions (22 orbits). Six patients had IgG4-RD, 3 RDD, and 5 c-ANCA-associated vasculitis. Overall, 13 (92.8%) patients displayed enlargement of V2, 12 (85.7%) of V1 and 7 (50%) of V3. Simultaneous enlargement of V1 and V2 was detected in 11 (78.6%) patients, and all 3 divisions were simultaneously involved in 6 (42.8%). Other radiological findings included abnormal contrast enhancement and soft tissue thickening in the cavernous sinus, Meckel’s cave, and/or the cisternal segment of the trigeminal nerve. Conclusions: Although trigeminal thickening associated with non-malignant orbital infiltration is commonly considered a sign of IgG4-RD, other conditions such as vasculitis and RDD should be considered in the differential diagnosis of these uncommon cases.