Bilateral optic nerve compression as a mechanism for the Foster Kennedy syndrome.

An 11-year-old boy with a juvenile nasopharyngeal angiofibroma developed optic disc pallor in one eye and optic disc edema in the other eye (Foster Kennedy Syndrome [FKS]). The mechanism was believed to be bilateral, asymmetric optic nerve compression. Review of the 36 previously reported cases of FKS revealed that 12 cases (33%) were probably also caused by bilateral optic nerve compression. Only eight (22%) of the cases satisfied Foster Kennedy's original hypothesis for the pathogenesis of his syndrome, namely, direct compression of one optic nerve causing atrophy and increased intracranial pressure causing contralateral papilledema. In 15 (41%) reported cases of FKS, descriptions were inadequate to determine a mechanism, while two (5%) were probably caused by long-standing increased intracranial pressure without direct optic nerve compression. The authors believe that as sophisticated imaging permits earlier diagnosis and more precise localization, most future cases of FKS caused by mass lesions will be found to result from bilateral direct optic nerve compression.