Foster-Kennedy syndrome vs Pseudo-Foster-Kennedy syndrome

Summary • True Foster-Kennedy syndrome o Presentation -Optic disc edema in one eye + optic atrophy in the other eye o Cause -Tumor pressing on ipsilateral optic nerve, causing optic atrophy in one eye -Increased intracranial pressure from tumor causes papilledema in the other eye -Tumor is most commonly slow-growing, enlarging anterior cranial fossa meningioma • Usually frontal, olfactory, or sphenoid wing meningioma • Pseudo-Foster-Kennedy syndrome o Also presents with optic atrophy in one eye and optic disc edema in the other eye o How to differentiate -Usually there is a history of loss of vision in the optic atrophy eye before -Most common cause of Pseudo-Foster-Kennedy syndrome is bilateral and sequential NAION (non-arteritic anterior ischemic optic neuropathy) • Had optic atrophy from first event • One year or two later, present with optic disc edema as second event o So, the eye with vision loss due to optic disc edema is NOT papilledema but recurrent NAION. • Management o True Foster-Kennedy syndrome -MRI o Pseudo-Foster-Kennedy syndrome -no MRI, treat risk factors for NAION o If you cannot elucidate history of bilateral and sequential optic neuropathy with disc edema -MRI