Optic neuropathy secondary to cat scratch disease: distinguishing MR imaging features from other types of optic neuropathies.

BACKGROUND AND PURPOSE MR imaging characteristics of optic neuropathy caused by cat scratch disease have not yet been described; this lack of information may result in incorrect diagnosis and may contribute to initiation of inappropriate therapy. Our study was based on the hypothesis that cat scratch disease-related optic neuropathy has distinct MR imaging features compared with those of other types of optic neuropathies. METHODS Eighty-two patients with various causes of optic neuropathy and available MR imaging examinations were included in this study. Two readers blinded to the diagnosis reviewed the MR images independently in regard to presence, location, and extent of optic nerve enhancement. The MR imaging findings were correlated with the final diagnosis. RESULTS Eleven percent (9/82) of the patients received a final diagnosis of cat scratch disease. Optic nerve enhancement in patients with cat scratch disease (5/37) was localized to a 3- to 4-mm segment at the optic nerve-globe junction. All other patients with optic neuropathy (31/37) with one exception showed enhancement away from the optic nerve-globe junction or a long-segment enhancement when the optic nerve-globe junction was also involved. Four patients with cat scratch disease did not show any optic nerve MR abnormalities. CONCLUSION Unilateral, short-segment enhancement localized to the optic nerve-globe junction is highly specific for cat scratch disease as the underlying cause of optic neuropathy and may help in establishing the diagnosis of this condition.