Rehabilitation physicians and neuroscientists from Taiwan have found, in a very large case-control study involving nearly 300,000 people, that traumatic brain injury nearly doubles the risk of developing multiple sclerosis over the subsequent six years. Using insurance databases, they examined the records of 72,765 people with traumatic brain injury and their risk of developing MS over the next six years, and compared this with the incidence of MS in a matched group of 218,295 people from the database who had not had such an injury. The risk of developing MS over the subsequent six years was nearly double (1.97, p<0.01) for those with a head injury. On average in this study, MS developed around 18 months after the injury.
This confirms the belief that many people with MS have had that a significant head injury can predispose to MS. There are a number of mechanisms through which this association may operate, including disruption of the blood-brain barrier, vascular disruption and possibly the stress of the event. This ties in to some extent with recent research from the inventor of the MRI, that MS may be associated with blockages to the flow of cerebrospinal fluid in the neck related to trauma.