MRI of the orbits of a 38-year-old woman with slowly progressive painless visual loss shows thickening of the left intraorbital optic nerve with a rim of enhancement surrounding a central non-enhancing core, producing a 'tram-track' appearance. The MOST likely diagnosis is:

• A Optic nerve glioma
• B Metastatic infiltration of the optic nerve
• C Optic neuritis
• D Optic nerve sheath meningioma ✓

Explanation

The tram-track sign, circumferential enhancement of the dural sheath around a central non-enhancing nerve, is characteristic of optic nerve sheath meningioma, seen on axial contrast-enhanced MRI. It affects middle-aged women and causes slowly progressive visual loss with later optociliary shunt vessels. An optic nerve glioma enlarges the nerve itself and enhances diffusely rather than sparing a central core, typically occurring in children, often with neurofibromatosis type 1.

Reference: Kanski's Clinical Ophthalmology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.