Unprovoked seizures after traumatic brain injury: A population-based case-control study.
OBJECTIVE
To quantify the risk of unprovoked seizures after traumatic brain injury (TBI) METHODS: We used the Stockholm Incidence Registry on Epilepsy to carry out a population-based case-control study, including 1,885 cases with incident unprovoked seizures from September 1, 2000 through August 31, 2008, together with 15,080 matched controls. Information of prior hospitalizations for TBI was obtained through record linkage with the Swedish National Inpatient Registry for the period 1980-2008. Relative risks (RRs) for unprovoked seizures were estimated after various TBI diagnoses, and influences of TBI severity and time since trauma were studied in detail.


RESULTS
After hospitalization for mild TBI, the RR was 2.0 (95% confidence interval [CI] 1.5-2.7). The RR was higher after brain contusion (5.9, 95% CI 2.4-15.0) or intracranial hemorrhage (ICH) (4.5, 95% CI 2.2-9.0), whereas a combination of both diagnoses led to a further sevenfold increase in RR (42.6, 95% CI 12.2-148.5). The risk was greatest during the first 6 months after severe TBI (RR 48.9, 95% CI 10.9-218.9) or mild TBI (RR 8.1, 95% CI 3.1-21.7), but was still elevated >10 years after any TBI.


CONCLUSIONS
Herein we present a large population-based case-control study on TBI as a risk factor for unprovoked epileptic seizures, including cases of all ages with individually validated seizure diagnoses. The risk for epileptic seizures was substantially increased after TBI, especially during the first 6 months after the injury and in patients with a combination of ICH and brain contusion.
Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
Benno
B
Mahler
Epidemiology Unit, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
Sofia
S
Carlsson
Center for Occupational and Environmental Medicine, Stockholm County Council, Stockholm, Sweden.
Tomas
T
Andersson
Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
Cecilia
C
Adelöw
Epidemiology Unit, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
Anders
A
Ahlbom
Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
Torbjörn
T
Tomson
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001930:Brain Injuries / Q000150:complications* / Q000453:epidemiology*; D016022:Case-Control Studies; D018672:Community Health Planning; D004569:Electroencephalography; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012306:Risk; D012640:Seizures / Q000453:epidemiology* / Q000209:etiology*; D012680:Sensitivity and Specificity; D012737:Sex Factors; D013997:Time Factors
Case-control; Epidemiology; Epilepsy; Population-based; Seizure; Traumatic brain injury