WEDNESDAY, Feb. 11, 2015 (HealthDay News) -- After a stroke, driving skills may be impaired, two new studies suggest.
The small studies found that drivers who survived a recent stroke were more likely than other drivers to make serious driving errors. Stroke survivors were also more likely to get into collisions when in a simulated driving test environment.
"Patients with acute minor stroke made more errors during driving simulation in cognitively demanding aspects of driving, such as left-hand turns at a busy intersection," said one of the study's lead authors, Megan Hird. She is a graduate student at the University of Toronto and researcher at St. Michael's Hospital in Toronto.
Hird explained that few studies have looked at the driving performance of patients soon after a mild stroke. And while guidelines may suggest waiting a month to begin driving again, people may start driving sooner, according to Hird.
To see how a stroke might affect driving ability, Hird and her colleagues recruited 10 patients who had experienced a mild ischemic stroke (in which blood flow to the brain is interrupted by a blood clot) within the past seven days. The researchers had the stroke survivors drive in a simulated environment. They compared those results to the simulated driving tests of 10 healthy people who hadn't had a stroke.
Overall, the stroke patients made twice as many driving errors as the comparison group. They were also about four times as likely as the healthy people to make mistakes when they were told to follow a bus, a task that requires significant attention, according to the researchers.
Hird's colleague, Kristin Vesely, also a graduate student at the university and hospital, led a second study comparing the driving abilities of nine patients who had had a subarachnoid hemorrhage with nine people who had not had a stroke. A subarachnoid hemorrhage involves bleeding at the base of the brain.
The people who had hemorrhagic strokes, which typically take longer to recover from, completed the driving simulation test three months after their strokes, according to the study.
The researchers found that the stroke survivors had more than twice the number of collisions compared to people who hadn't experienced a stroke. They were also three times as likely as the drivers without strokes to drive outside road lines, the study found. Additionally, stroke survivors made more errors when making left turns, Vesely said.
The researchers were scheduled to present their findings Wednesday at the annual meeting of the American Stroke Association in Nashville. Studies presented at medical meetings are viewed as preliminary until published in a peer-reviewed medical journal.
The findings are not surprising, said Dr. Doojin Kim, director of the stroke program at the UCLA Medical Center, Santa Monica, and associate professor of neurology at the David Geffen School of Medicine, University of California, Los Angeles.
Kim recommends his stroke patients to wait before driving, but the length of the waiting period depends on the severity of the stroke and the rate of improvement.
"Certainly after a patient has had a stroke, depending on the symptoms, I will tell certain patients not to drive and others that they can," he said.
While the new studies add information, one limitation is the small numbers of patients, Kim said. He said he evaluates patients on an individual basis. "I advise some to get their driving evaluated," he said.
Kim may refer them to a rehab facility, where they can get a driving simulator test. "If they or their family doesn't think they are safe, they can certainly go for a driving test at the DMV," he said.
Guidelines about waiting periods for driving after a stroke vary, Vesely and Hird said. In the United States, guidelines are state-dependent. Checking with your state's Department of Motor Vehicles is advised.
To learn more about driving after a stroke, visit American Stroke Association.