Orbital Nerve Enlargement: A Narrative Review.

PURPOSE: This narrative review summarizes the causes of infraorbital and frontal nerve enlargement and their radiological features on magnetic resonance imaging and computed tomography.

METHODS

We conducted a systematic search of the literature, including PubMed, Ovid MEDLINE, EMBASE, Cochrane Library, and Google Scholar in May 2025. Studies were included if they reported a case of infraorbital and/or frontal nerve enlargement with magnetic resonance imaging or computed tomography correlation and specified the underlying etiology. This was supplemented by a series of cases to illustrate characteristic radiological features across pathologies.

RESULTS

Enlargement of the orbital nerves, particularly the infraorbital and frontal nerves, may be secondary to a range of underlying pathologies, including inflammatory, neoplastic, infectious, and traumatic diseases. Immunoglobulin G4-related ophthalmic disease is the most frequently reported cause and commonly presents with bilateral infraorbital nerve enlargement. Other causes include reactive lymphoid hyperplasia, lymphoma, schwannoma, traumatic neuroma, and perineural spread of malignancy. Infectious causes such as invasive aspergillosis and mucormycosis, and inflammatory conditions such as idiopathic granulomatous orbital inflammation and orbital inflammatory syndromes, have also been reported. This narrative review summarizes the causes of infraorbital and frontal nerve enlargement and their radiological features on magnetic resonance imaging and computed tomography.

CONCLUSIONS

Infraorbital and frontal nerve enlargement, while uncommon, can arise from diverse etiologies. Infraorbital nerve enlargement is characteristic of immunoglobulin G4-related ophthalmic disease, particularly bilateral enlargement. Unilateral enlargement of any orbital nerve is most commonly due to primary nerve tumors or perineural spread of malignancy.