by Richard Ellin, MD, FACP
Question: I am an experienced rider, have ridden all my life and am 68 now. Nearly a year ago I had a crash on the second day of a 600 km Audax brevet, after riding 475 km. Because of head injuries I have no memory of the crash, but a witness said no other vehicle was involved. He just saw me sailing over the handlebars. [I unfortunately happened to land on my ear on a piece of concrete and my helmet didn’t save me from serious head injury (4 weeks in the hospital).] Ever since then I have been trying to figure out what might have happened. I would like to hear medical opinions about whether a cyclist can pass out without any warning symptoms or, if there are warning symptoms, what to be aware of. — Glen T.
Dr. Richard Ellin Responds: There are many possible causes of passing out, or what is known as syncope, in medical parlance. This can happen to anyone, at anytime.
Some of the more common causes include various heart conditions, anemia, and certain medications. Needless to say, if it happens when one is cycling or driving a car, it is potentially far more dangerous — for exactly the reasons you raised in your question.
Since you spent time in the hospital, Glen, I presume you had a thorough medical evaluation. However, sometimes even that will not reveal a specific cause. In cases such as yours, physicians at least try to make sure that you didn’t pass out due to a heart problem. If that was ruled out by your doctors, then whatever caused you to pass out is probably not serious, and less likely to recur.
However, if your medical team did not rule out a heart problem and could not pinpoint the cause, you should seek further testing.
A number of medical tests are typically done when investigating why a person may have passed out. If the initial evaluation, including various blood tests and an EKG, don’t reveal a cause, then further testing is often done.
Such additional tests typically include a Holter monitor (wearing a portable heart monitor for 24-48 hours), to try to identify intermittent abnormal heart rhythms, and an echocardiogram, to identify structural abnormalities of the heart.
Sometimes an EEG (recording of one’s brain electrical activity) is done as well, to make sure the person did not have a seizure. There are certain medications that could conceivably cause a passing out episode, although this is somewhat unusual.
Of course, make doubly sure you remain well-hydrated when cycling, especially on longer rides. If at any time you feel a little dizzy or lightheaded, get off the bike, and let your doctor know about it.
Richard Ellin, MD, FACP, is a board-certified specialist in Internal Medicine who practices in Alpharetta, Georgia. He received his medical degree and completed residency at Emory University, and has been in practice with Kaiser Permanente for more than 26 years. He is also an avid cyclist.
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