Syncope is a transient loss of consciousness that is usually caused by the interruption of blood flow to the brain. People who have syncope often can display seizure-like activity (namely, muscle jerking) that can be mistaken for epilepsy.
Being labeled as having epilepsy can dramatically alter a young person's life, not in the least because of the inappropriate stigma that is still often attached to that diagnosis. More importantly, making the diagnosis of epilepsy in error most often leads to ineffective therapy, since the therapy is aimed at the wrong diagnosis - so the "spells" continue to occur despite treatment. Even worse, at least some of the arrhythmias (abnormal heart rhythms) that cause syncope and are misdiagnosed as epilepsy can become fatal if they are not recognized and treated appropriately.
Two Types of Syncope Most Often Misdiagnosed as Epilepsy
It appears that two specific causes of syncope are most commonly misdiagnosed as epilepsy in children and young adults: vasovagal syncope and long-QT syndrome.
Vasovagal syncope (also called the simple fainting spell) occurs due to a reflex often triggered by pain, fright, an upset stomach, or many other things. This reflex causes the blood vessels in the legs to dilate. Blood suddenly pools in the legs, reducing the volume of blood returning to the heart and lowering blood pressure -- causing the victim to lose consciousness. Once he or she becomes supine (most often by falling down), gravity allows the blood to return to the heart, and consciousness is rapidly regained.
Long QT syndrome is an inherited disorder of the heart's electrical system (which controls the heart beat). People who have long QT syndrome can develop sudden, unexpected episodes of a peculiar variety of ventricular tachycardia (a potentially dangerous rapid heart rhythm), that commonly leads to sudden syncope, and that can even lead to sudden cardiac arrest and death.
People who have either vasovagal syncope or long QT syndrome can usually be treated quite effectively, once the diagnosis is made correctly.
In one study, in 222 patients with vasovagal syncope, 8% had seizure-like activity when they lost consciousness during a tilt table study. None of these patients proved to have evidence of a true seizure disorder after an extensive neurological examination, including EEG tests (the electroencephalogram test, which most often shows abnormal brain activity in people with epilepsy). Many of these patients, however, had inappropriately been given the diagnosis of epilepsy prior to their tilt table test, and several had been receiving anti-epilepsy medications (which are ineffective in vasovagal syncope), and had been given severe driving restrictions based on the incorrect diagnosis.
In another study, investigators reviewed the New Zealand Cardiac Inherited Disease Registry, and found that in 31 people they identified who had long QT syndrome, 13 had experienced long delays in receiving the correct diagnosis (an average delay of 2.4 years, but up to 20.7 years). Many of these delays were related to an incorrect diagnosis of epilepsy. And during these delays all these patients were at risk for sudden death. (Notably, anyone who had died suddenly after an incorrect diagnosis would never have received the correct diagnosis, and would not have been included in this particular registry.)
What to Do If You're Worried You Have Been MisdiagnosedIf you or a loved one has been given a diagnosis of seizure disorder or epilepsy, and the EEG test is normal -- and especially if seizure-like episodes have persisted despite treatment -- you should insist on a re-evaluation. Specifically, you should ask your doctor to consider vasovagal syncope and long QT syndrome as potential diagnoses.
Passman R, Horvath G, et al. Clinical spectrum and prevalence of neurological events provoked by tilt table testing. Archives of Internal Medicine . 2003;163:1945-1948.
MacCormick JM, McAlister H, Crawford J, et al. Misdiagnosis of long-QT syndrome as epilepsy at first presentation. Ann Emerg Med 2009; 54:26-32.