Multiple sclerosis is the most common disease of the central nervous system (the brain and spinal cord) affecting young adults.1

In MS, the insulating sheath (myelin) around nerve fibres (axons) is damaged.2

When MS is in its early stages the central nervous system can often repair damaged areas, or reroute messages via different pathways. This is what is happening when episodes of symptoms are followed by periods of reduced or even no symptoms (relapsing-remitting MS).3

However, if the damage is extensive, communication with the affected part of the central nervous system may become permanently blocked.3

The cause of MS is not fully understood. It is thought to be a combination of environmental and genetic factors.4