Viual Field Defects: Craniopharyngoma vs Pituitary Adenoma

[lemonade90]

Why does a pituitary adenoma begin as a bitemporal superior quadrantopia while a craniopharyngioma begin as a bitemporal inferior quadrantopia?

From my understanding the posterior pitutary is formed by a more superiorly arising neuroectoderm while the anterior pituitary is formed via the more inferiorly arising oral ectoderm. I would think if this was the case that the superior arising structure would compress the superior portion of CN II which carries fibers from the superior retina...therefore one should get visual field loss of the inferior visual field component (i.e. pituitary adenoma should give you a bitemporal inferior quadrantopia). What am I missing?

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[AndyRSC]

It doesn't seem like you're missing anything. If a mass is superior to the optic chiasm, as with craniopharyngiomas, which tend to be suprasellar - the visual field defect will first appear as bitemporal inferior quadrantanopia; if originating inferior to the optic chiasm, the visual field defect will first appear as bitemporal superior quadrantanopia.

 

[aspiringmd1015]

is there any other way we're suppose to knwo how to differentiate b/w a craniopharyngioma and pituitary adenoma?

 

[EmetyreUSMLEStep1Tutor1]

Why does a pituitary adenoma begin as a bitemporal superior quadrantopia while a craniopharyngioma begin as a bitemporal inferior quadrantopia?

From my understanding the posterior pitutary is formed by a more superiorly arising neuroectoderm while the anterior pituitary is formed via the more inferiorly arising oral ectoderm. I would think if this was the case that the superior arising structure would compress the superior portion of CN II which carries fibers from the superior retina...therefore one should get visual field loss of the inferior visual field component (i.e. pituitary adenoma should give you a bitemporal inferior quadrantopia). What am I missing?

Because brain reverse image upside down. Craniopharyngyoma push optic chiasm from the roof, and pituitary adenoma from the basement