The Misdiagnosis of Epilepsy

Many are inappropriately labeled as having seizures

Doctor and patient holding hands in hospital
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If you or a loved one is a young person who has been diagnosed with epilepsy, you should be aware that sometimes this diagnosis is mistaken. It is not that uncommon for young people to be given the diagnosis of epilepsy (or seizure disorder) when they do not have epilepsy at all. Instead, they may have a condition known as syncope.

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), which can be mistaken for epilepsy.

Implications of Mislabeling the Diagnosis

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 erroneous diagnosis of epilepsy most often leads to therapy that will be ineffective, and that exposes people to unnecessary adverse effects. Because the episodes are likely to continue, a succession of useless drugs may be used. 

Also, because the real diagnosis — syncope — has been missed, the underlying cause of the syncope will not be sought out. Some of these underlying causes, such as cardiac arrhythmias, carry significant risks if they go undetected. .

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 because of a neurological reflex that is 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 cardiac 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. And many restrictions that may be placed on people with epilepsy, such as driving restrictions, are usually not necessary after the correct diagnosis has been made, and effective treatment instituted.

How Often Does This Happen?

The misdiagnosis of epilepsy appears to occur disturbingly frequently.

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 people had been given the incorrect diagnosis of epilepsy prior to their tilt table test, and several had been receiving ineffective anti-epilepsy medications, along with 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.)

A Word From Verywell

If 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.

Sources:

Krumholz A, Wiebe S, Gronseth GS, et al. Evidence-based Guideline: Management of an Unprovoked First Seizure in Adults: Report of the Guideline Development Subcommittee of the American Academy of Neurology and the American Epilepsy Society. Neurology 2015; 84:1705.

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.

Passman R, Horvath G, Thomas j, et al. Clinical Spectrum and Prevalence of Neurological Events Provoked by Tilt Table Testing. Archives of Internal Medicine. 2003;163:1945-1948.

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