T1 pre-gad T1 post-gad with fat sat T1 post-gad with fat sat

Diagnosis: Optic neuritis due to multiple sclerosis

Optic neuritis is a non-specific inflammation of the optic nerve which may be associated with multiple sclerosis in 50% of cases. Other etiologies of optic neuritis include radiation, pseudotumor, sarcoidosis, and viral etiologies. Patients typically present with acute or subacute visual loss. On imaging, optic neuritis may demonstrate inflammatory changes within the orbit such as abnormal enhancement within the intraconal fat best seen on fat suppressed T1 weighted post gadolinium images. The optic nerve may enhance & be enlarged and the process may be bilateral.

Some things to consider when you see inflammatory changes in the intraconal fat include optic neuritis, lymphoma, Graves and pseudotumor. Involvement of the optic nerve is atypical for all of these except optic neuritis. Optic nerve glioma and meningioma may produce enhancement involving the optic nerve, but would not cause inflammation of the orbital fat. In addition to her visual problems, this patient also had some left sided weakness and cerebellar dysfunction on neurologic examination. In addition her brain MR showed a few periventricular white matter lesions which were perpendicular to the ventricles suggestive of MS. Her symptoms improved after steroid therapy. Related Cases

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Guy J, Mao J, Bidgood WD, et al. Enhancement and demyelination of the intraorbital optic nerve. Fat suppression magnetic resonance imaging. Ophthalmology May 1992; 99 (5):p713-9/

Mukherji SK, Tart RP, Fitzsimmons J, et al. Fat-suppressed MR of the orbit and cavernous sinus: comparison of fast spin-echo and conventional spin-echo. AJNR Oct 1994; 15(9):p1707-14.

Orbital sarcoidosis Optic nerve glioma Orbital lymphoma