Prior research has shown that traumatic brain injury carries a high risk of seizure in the weeks to months after the event. The duration of this elevated risk, however, was not known.
Dr. Jakob Christensen, from Aarhus University Hospital, Denmark, and colleagues assessed the long-term risk of epilepsy by analyzing data from 1.6 million people who were born in Denmark from 1977 to 2002, with followup data for a total of 19.5 million person-years.
During the study period, about 78,500 people had a traumatic brain injury and approximately 17,500 people developed epilepsy. The relative risks for epilepsy were 2.22 and 7.40 with mild and severe brain injury, respectively. Skull fracture increased the risk by 2.17-fold.
Beyond 10 years, the relative risks of epilepsy were still 1.51, 4.29, and 2.06 for mild brain injury, severe injury, and skull fracture, respectively.
The likelihood of seizures was directly related to the age at injury and was especially high for those who were older than 15 years of age: their relative risks were 3.51 and 12.24 for mild and severe injuries, respectively. High risks were also seen in patients with a family history of epilepsy.
Women were slightly more likely than men to experience a seizure.
This study “does not address the value of treatment, but the risk estimates will help patients and doctors make decisions more clearly,” Dr. Simon Shorvon and Dr. Aidan Neligan, from University College London Institute of Neurology, comment in a related editorial.