The diagnosis of MS has previously been a long, slow and complicated process, since there was no definitive laboratory test for MS. The newer and sophisticated brain scanning techniques that are now used, such as magnetic resonance imaging (MRI) can locate lesions or patchy scarring (scleroses) in the nervous system, but require very careful interpretation by a skilled doctor. Although many people in the early stages of MS do not exhibit the ‘classic’ symptoms considered to be the ‘textbook’ features of the disease, MRI can be the definitive test as it shows lesions in the white matter which contains myelinated fibres. Finally, many other conditions may produce symptoms almost indistinguishable from MS symptoms. Thus the difficulty in diagnosing MS lies in establishing sufficient evidence to exclude other possibilities. There is more about diagnosing MS in Multiple Sclerosis – the ‘at your fingertips’ guide.