News Release

Mayo clinic proceedings study supports shorter waiting period for driving privileges after a seizure

Peer-Reviewed Publication

Mayo Clinic

SCOTTSDALE, Ariz. -- Drivers in Arizona who got behind the wheel three months after a seizure did not have more seizure-related crashes compared with those who waited one year before driving, say researchers in the July issue of Mayo Clinic Proceedings.

The researchers, who studied motor-vehicle crash data, say the results should prompt additional research to determine the length of time a driver should be seizure-free before being allowed to resume driving.

"Our study suggests that reducing the seizure-free interval from 12 to three months did not produce a significant increase in total crashes, crashes per mile driven and crashes per estimated driver with epilepsy," says Joseph Drazkowski, M.D., a neurologist at Mayo Clinic in Scottsdale who was the lead author of the study. "Rules, regulations and laws pertaining to driving with epilepsy should be based on the best available data."

In 1994 the state of Arizona reduced the "seizure-free interval" from 12 months to three months. This allowed researchers to review state motor-vehicle crash data three years prior to and three years following the change in the law.

In their analysis, researchers found that seizure-related crashes increased by 11 during the study period. Crashes related to other medical conditions increased from 288 to 310, while deaths due to seizure-related crashes decreased.

Epilepsy affects more than 2.5 million people in the United States. Epilepsy consists of unpredictable, recurrent episodes of loss of sensory motor control or consciousness.

The Mayo researchers note that little data exist to guide establishment of a seizure-free interval. In the United States, the interval ranges from three months to 18 months.

Including Dr. Drazkowski, those involved in the study included: Joseph Sirven, M.D., and Bart Demaerschalk, M.D., Department of Neurology at Mayo Clinic in Scottsdale; Joseph Hentz, Department of Biostatistics at Mayo Clinic in Scottsdale; David Labiner, M.D., Department of Neurology at the University of Arizona; Lori Uber-Zak, D.O., Department of Neurology at Loma Linda University (Calif.); and Robert Fisher, M.D., Department of Neurology at Stanford University.

In an editorial in the same issue of Mayo Clinic Proceedings, Allan Krumholz, M.D., a neurologist at the Maryland Epilepsy Center, University of Maryland School of Medicine-Baltimore, says future clinical studies are needed to confirm this study's findings, but notes that the current study provides evidence that a three-month seizure-free interval is a reasonable standard.

Dr. Krumholz says that a shorter waiting period -- although potentially increasing the individual risk of a crash -- may actually reduce the cumulative crash risk by promoting compliance with legal driving rules. He notes that many individuals never report their disorder to authorities despite legal requirements to do so because they are afraid of losing their driving privileges for an extended time.

"Regulations and standards governing driving eligibility vary dramatically from state to state. Because of the lack of good data on driving risks for people with epilepsy, such regulations and standards are often arbitrary," Dr. Krumholz says. The study by Dr. Drazkowski and others provides evidence that the three-month seizure-free interval is a reasonable standard.

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Mayo Clinic Proceedings is a peer-reviewed and indexed general internal medicine journal, published for more than 75 years by Mayo Clinic, with a circulation of 130,000 nationally and internationally.

Contact:
John Murphy
507-284-5005 (days)
507-284-2511 (evenings)
e-mail: newsbureau@mayo.edu


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