Just a little anecdote. One of my girlfriend's husband is a great neurologist and he told me that years back when he was in med school one of their cadavars was a woman who had a "stroke" back in her 20s. It left permanent damage to her gait but if I remember correctly she lived the rest of her life without any other issues until she got much older and had eye problems which were attributed to her age. Upon autopsy she was diagnosed with Multiple Sclerosis. Before MRI it was anyone's best guess, imo.