A retrospective case-control study to identify clinical risk factors for seizure-related motor vehicle crashes in 50 patients with epilepsy and 50 matched control patients was performed at Johns Hopkins University, Baltimore, MD. The majority (54%) of patients who crashed were driving illegally, having a history of poor seizure control; 25% had more than one crash related to a seizure and 20% had missed a dose of medication just prior to the crash. Patients with well controlled epilepsy, and no seizure recurrence for more than 12 months had a 93% reduction in risk of a crash, compared to patients with more frequent seizure recurrence. The presence of reliable auras with seizures, and few prior nonseizure-related accidents decreased the odds of seizure-related accidents. 
COMMENT. Patients with epilepsy of driving age may be counseled that factors known to reduce the risk of seizure-related automobile accidents include optimal AED therapy with long seizure-free intervals, reliable auras, and few prior nonseizure-related accidents. The authors comment that if the 50 patients who had crashed had honored a 12-month legally defined seizure-free restriction, 74% of crashes might have been averted. A longer seizure-free restriction on driving could lead to poor compliance and a higher risk of crashes. Patients whose medication was closely monitored and optimized showed an 89% reduction in risk of crashes.
Berg AT and Engel J Jr, in an editorial, discuss “Restricted driving for people with epilepsy.” . The minimum seizure-free interval of 12 months is the strongest predictor of avoidance of motor vehicle accidents for patients with epilepsy. This 1-year restriction on driving is generally appropriate and is mandated by the European Union Association of International Bureau for Epilepsy. A US consensus development workshop opinion, approved by the AAN, AES, and EFA, recommends a minimum 3-month seizure-free interval, recognizing the importance of the neurologist’s input and need to consider mitigating factors. The study by Krauss et al provides evidence for some of the factors that may permit reduction of the 1-year restriction in certain individuals: eg reliable aura, accident-free prior driving record, and close AED monitoring and compliance.