Occasionally, there may be mental changes such as forgetfulness or confusion. These symptoms may occur in any combination, may come and go, and may vary from very mild to very severe. At present, there is no way to predict when or even if attacks of the disease will occur. Symptoms not only vary greatly from person to person but may also vary from time to time in the same person. The most typical pattern of MS is marked by periods of active disease or attacks, called exacerbations or relapses, followed by quiet periods called remissions.
Some people have few attacks and little if any disability over time.
This means they have exacerbations, which take place unpredictably, followed by periods of partial or total remission, which may last months or even years. Thus, the disease ranges from very mild to intermittent to steadily progressive. Because MS affects individuals so differently, it is difficult to make generalizations about the extent of disability any one person may sustain. Statistics suggest that two out of three people with MS remain ambulatory over their lifetimes, but many of them will need a cane or other assistive device. A definite diagnosis can take several months.