GLIOMAS OF THE CHIASM
Ophthalmologists have long been familiar with the gliomas that involve the optic nerve in its intra-orbital course. Less well known are the tumors of similar type that arise from the chiasm or adjacent wall of the third ventricle, whence they spread forward in some instances even as far as the retinal end of the optic nerve. In a paper written with Paul Martin,10 several years ago, seven of these cases, most of which had been clinically diagnosed as retrobulbar neuritis, were fully described.
These tumors may cause the typical chiasmal syndrome in question, and as the sella remains unaffected they may therefore be symptomatically indistinguishable from a meningioma; but as a rule, they have certain characterizing features that serve to make the clinical diagnosis probable if not certain.
In the first place, they are largely restricted to childhood and consequently scarcely deserve inclusion