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Seizure-Like
Attacks May Mean Cardiovascular Problems, Not Epilepsy
(July
1, 2000)--Physicians have long suspected that many patients
being treated for epilepsy aren't actually suffering
from the disease. Now a new study published in the July
2000 issue of the Journal of the American College
of Cardiology reveals that the rate of misdiagnosis
may be more than 40 percent.
"Two
out of five patients in our study had been told that
their blackouts were caused by epilepsy, and many were
taking powerful drugs to treat the condition--with little
if any benefit," explained lead author Dr. Amir Zaidi,
of the Manchester Heart Centre at the Royal Infirmary
in Manchester, England. "In reality, these patients
had heart or circulation problems that could be effectively
treated with cardiac drugs or pacemakers."
The
study was born when local neurologists began sending
Dr. Zaidi epilepsy patients who had uncertain diagnoses
or who had failed to respond to anticonvulsant medication.
In the resulting study, Dr. Zaidi and his colleagues
put 74 of these patients through simple cardiovascular
tests--head-up tilt tests and carotid sinus massage--to
see if their problems were really cardiovascular in
nature. In the head-up tilt test, patients are strapped
to a table and slowly tilted until they are nearly vertical;
blood pooling in the legs reduces blood flow to the
heart and causes fainting in susceptible individuals.
In carotid sinus massage, pressing on the carotid artery
in the neck slows the heart down and causes fainting
in susceptible individuals.
What
Dr. Zaidi and his research team found surprised them.
Almost 42 percent of the patients had been incorrectly
diagnosed with epilepsy. Instead, many suffered from
a severe form of fainting called vasovagal syncope.
"We
were taken aback by the level of misdiagnosis, which
was at least twice as high as expected," said Dr. Zaidi,
noting that other studies have suggested misdiagnosis
rates of only 20 percent. "The most important message
of our study is that if a patient with seizure-like
attacks thought to be caused by epilepsy does not respond
to treatment, the physician should reconsider the diagnosis."
For
Dr. Melvin M. Scheinman, of the University of California,
San Francisco, the study's value lies in its discovery
of just how common the misdiagnosis of epilepsy is.
"It
has long been appreciated that apparent 'epileptic fits'
may have a cardiac cause," said Dr. Scheinman. "The
importance of Dr. Zaidi's study is to highlight the
frequency of this association."
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