What you see is what you get

The history of neurology is replete with attempts to link function with specific anatomic centers that orchestrate particular neurologic capabilities. Phrenology was an accepted discipline in the 19th century, led by Joseph Gall, who developed elaborate scalp surface maps of the head in order to identify characteristic bumps that were hypothesized to correspond to specific attributes (functions, aptitudes, personalities).¹ This superficial approach failed to encompass the complexities of the brain and its constellation of discrete and interacting tract systems. While the concept of lesion localization was principally established by Charcot as a fundamental framework for neurologic thinking,² the evolution of MRI technologies in the 1980s represented a profound advance in our ability to understand the implication of localized brain lesions and their functional consequences.

Multiple sclerosis (MS) is a disorder characterized by a multiphasic course of clinically evident (eloquent syndromes) and radiographically occult disease (non-eloquent) events.³ The recognition that there is a striking mismatch between radiographic and clinical events (5–10:1) signifies that much of the disease process affecting the end organ is subclinical. In contrast with diabetes, hypertension, lupus, and other diseases that produce silent activity, MS is distinctive in that we can readily image the brain (the end organ) with conventional and nonconventional MRI techniques to reveal evidence of disease progression in those structural elements that are germane to neurologic functioning.

The visual system is almost always involved …