Fundamental Concepts in Localization

The ultimate diagnostic goal is to determine the exact pathophysiology underlying a patient’s symptoms. In neuro-ophthalmology, common symptoms include decreased vision, visual field defects, positive visual phenomena, double vision, oscillopsia, pain or numbness, ptosis, proptosis, or enophthalmos. The first goal of neuro-ophthalmic evaluation is clinical localization of the lesion, which may involve the following areas:

orbit

parasellar region: the chiasm superiorly and cavernous sinuses laterally

middle cranial fossa: the retrochiasmal visual pathways, including the optic tract, geniculate and optic radiations, and occipital cortex

posterior fossa: the brainstem and cerebellum

Each of these areas, as well as the clinical scenario and differential diagnosis, is associated with unique neuroimaging challenges that influence the choice of imaging modality (Table 2-5).

Table 2-5