Multiple sclerosis

A progressive disease of the central nervous system caused by the immune system attacking the protective myelin sheath around nerve fibres, causing them to fail or misfire. The randomness of the damage means that symptoms vary widely between individuals and over time, including blurred or double vision, loss of touch sensation, limb tremors, fatigue, and cognitive difficulties. Symptoms are both progressive in severity and intermittent — a person may be able to walk in the morning but not in the afternoon. MS is particularly relevant to accessibility because it can affect multiple modalities simultaneously and unpredictably: vision, motor control, cognition, and sensation may all be impaired to varying degrees. This makes MS a compelling case for adaptive interfaces that can respond to changing user capabilities within a single session, rather than relying on fixed accessibility settings.