Abstracts

Rationale: To estimate the occurrence of epilepsy following traumatic brain injury in Denmark between 1977 and 2002.Methods: We used the Danish Civil Registration System to identify all persons born in Denmark between 1977 and 2002 and the Danish National Hospital Register to identify persons registered with traumatic brain injury and epilepsy. Traumatic brain injury was divided according to clinical severity into 1) brain concussion, 2) cranial fractures, and 3) structural brain injury. Results: Among 1,605,216 persons born in Denmark between 1977 and 2002, we identified 73,326 persons with brain concussion, 5,099 persons with scull fracture and 3,850 persons with structural brain injury. We identified 17,470 persons registered with epilepsy in the follow-up period of 19,527,337 person-years. A total of 1,031 persons developed epilepsy after traumatic brain injury; 837 after brain concussion, 78 after cranial fractures and 116 after structural brain injury. There was an increased relative risk (RR) of epilepsy following concussion (RR = 2.22, 95% Confidence Interval (95% CI): 2.07 – 2.38); cranial fractures (RR = 2.17, 95% CI: 1.73 – 2.71), and structural brain injury (RR = 7.40, 95% CI: 6.16 – 8.89). For patients with concussions the development of epilepsy was significantly associated with gender, familial history of epilepsy, age at concussion, time since brain injury and number of concussions, but no association could be identified with duration of admission with concussion. There was a significant association between the development of epilepsy and duration of admission with scull fracture, but no other significant associations between scull fractures and epilepsy could be identified. For patients with structural brain injury there was a significant association between age at injury, duration of admission, and time since injury, but the association was not influenced by number of structural brain injuries, gender and familial history of epilepsy.Conclusions: Even mild traumatic brain injury (concussion) is associated with an increased risk of epilepsy. The study identifies several factors that are associated with the development of epilepsy after traumatic brain injury.