Imaging Spectrum of Infraorbital Nerve Pathology: Patterns, Etiologies, and Diagnostic Implications

Prior literature on comparative imaging analyses of the infraorbital nerve (ION) across infectious, inflammatory, benign, and malignant etiologies remains limited.

To characterize the ION imaging features across diverse non-traumatic etiologies and to identify patterns, including laterality, nerve thickness, and enhancement that may aid in etiological differentiation.

A retrospective review of radiology reports was conducted using the keywords "infraorbital nerve," "thickening," "prominence," "expansion," and "enhancement." Imaging studies were reviewed for features of ION involvement across pathologies, classified into four categories: IgG4-related disease; other inflammatory etiologies, comprising sinusitis, granulomatosis with polyangiitis, and foreign-body granuloma; benign etiologies, including neurofibroma, schwannoma, and benign lymphoid hyperplasia; and malignant perineural spread. The ION transverse diameter and height were compared between age-, sex-, and modality-matched controls and cases, and between groups.

The initial PACS keyword search yielded 491 studies, including 159 repeat examinations. The majority of studies were related to trauma, and 41 patients had non-traumatic unilateral or bilateral ION involvement. The mean±SD age of the patients was 69.3±13.6 years (range, 40-93 years), with 15 female patients. The mean±SD ION height measured 7.55±4.69 mm in IgG4-related disease vs 1.9±0.22 mm in controls (p=0.04), 2.68±0.79 mm in other inflammatory etiologies vs 1.95±0.14 mm in controls (p=0.07), 5.70±2.68 mm in benign etiologies vs 1.91±0.40 mm in controls (p=0.04), and 3.95±1.72 mm in malignant perineural spread vs 2.05±0.25 mm in controls (p<0.001). The mean±SD ION transverse diameter measured 8.06±4.69 mm in IgG4-related disease vs 2.05±0.31 mm in controls (p=0.04); 3.18±1.16 mm in other inflammatory etiologies vs 1.91±0.23 mm in controls (p=0.07); 5.72±0.60 mm in benign etiologies vs 2.11±0.22 mm in controls (p=0.04); and 4.45±1.74 mm in malignant perineural spread vs 2.17±0.27 mm in controls (p<0.001). Benign tumors demonstrated significantly greater infraorbital nerve height (p=0.04) and transverse diameter (p=0.04) than those with infectious/inflammatory diseases. No other pairwise or overall comparisons within the pathological groups demonstrated statistically significant differences.

Most pathologies affecting the ION are unilateral, including benign, malignant and other inflammatory etiologies. Bilateral ION nerve enlargement with significant nerve thickening could be considered a valuable radiologic indicator of IgG4-related ophthalmic disease.