Certified Neuroscience Registered Nurse (CNRN) Practice Exam

Which tumor is most likely to present with bitemporal hemianopia?

1. Pituitary adenoma

2. Menigioma

3. Acoustic neuroma

4. Neurofibroma

The correct answer is: Pituitary adenoma

Bitemporal hemianopia is a type of visual field loss that occurs when there is pressure on the optic chiasm, which is where the optic nerves from both eyes cross. The most common tumor associated with this condition is a pituitary adenoma. These tumors are located just below the optic chiasm, and as they grow, they can impinge on the chiasm, affecting the signals sent from the outer halves of each retina. This often results in a characteristic loss of vision in the outer visual fields of both eyes, leading to the bitemporal hemianopia. While other types of tumors can also affect vision, they do not have the same strong association. For example, meningiomas can occur near the optic nerve and cause vision problems, but they are not as frequently linked to bitemporal hemianopia specifically. Acoustic neuromas primarily affect the vestibulocochlear nerve and usually do not cause visual field defects. Neurofibromas may occur in various locations affecting nerves but are not typically associated with the specific visual field loss seen with pituitary adenomas. This anatomical and clinical understanding underscores why a pituitary adenoma is the most likely tumor to present with bitemporal hemianopia.