Risk of severe and repetitive traumatic brain injury in persons with epilepsy: A population-based case-control study

Background: While traumatic brain injury (TBI) can lead to epilepsy, individuals with preexisting epilepsy or seizure disorder (ESD), depending on the type of epilepsy and the degree of seizure control, may have a greater risk of TBI from seizure activity or medication side effects. The joint occurrence of ESD and TBI can complicate recovery as signs and symptoms of TBI may be mistaken for postictal effects. Those with ESD are predicted to experience more deleterious outcomes either because of having a more severe TBI or because of the cumulative effects of repetitive TBI. Methods: We conducted a case-control study of all emergency department visits and hospital discharges for TBI from 1998 through 2011 in a statewide population. The severity of TBI, repetitive TBI, and other demographic and clinical characteristics were compared between persons with TBI with preexisting ESD (cases) and those without (controls). Significant differences in proportions were evaluated with confidence intervals. Logistic regression was used to examine the association of the independent variables with ESD. Results: During the study period, 236,164 individuals sustained TBI, 5646 (2.4%) of which had preexisting ESD. After adjustment for demographic and clinical characteristics, cases were more likely to have sustained a severe TBI (OR = 1.49; 95% CI = 1.38-1.60) and have had repetitive TBI (OR = 1.54; 95% CI = 1.41-1.69). Conclusion: The consequences of TBI may be greater in individuals with ESD owing to the potential for a more severe or repetitive TBI. Seizure control is paramount, and aggressive management of comorbid conditions among persons with ESD and increased awareness of the hazard of repetitive TBI is warranted. Furthermore, future studies are needed to examine the long-term outcomes of cases in comparison with controls to determine if the higher risk of severe or repetitive TBI translates into permanent deficits. (C) 2014 Elsevier Inc. All rights reserved.