Can multiple sclerosis (MS) be caused by an injury?

The exact relationship of injuries to onset of multiple sclerosis (MS) has long been debated. The patient will naturally try to relate onset to a definable incident. Many case studies are very convincing - injuries are dramatic events that will easily be remembered by patients - but they are not truly valid statistical evidence. McAlpine believed, "Trauma to a limb or any part of the body, slight or severe, including operations, may occasionally precipitate the disease in a predisposed person or cause a relapse."

In a 1972 study of 250 MS patients, McAlpine's researchers found that 14 percent had an injury within three months prior to onset. In a parallel study of 250 patients with other diseases, only 5.4 percent had an injury within three months prior to onset. Although the studies showed a significant difference, most authorities do not believe that injury actually causes MS. It is more likely that injury brings out symptoms of an existing lesion that was previously silent.