Medical Test: Why Absence Seizures Are Missed on EEG

Seizure disorders have become increasingly more common in recent years as more and more children are born with neurological disorders of a genetic nature. If you are caring for a child who seems to be suffering from some form of seizure complication, it is important to become familiar with the types of testing that can be done and why, at times, the presence of some seizures, such as an absence seizure, are missed on EEG testing.

Many diagnostic medical tests provide false positive results as well as false negative results. It is for this reason that physicians will often run multiple tests as a way of ruling out a condition, or confirming a diagnosis. Much like treating conditions like spontaneous bacterial peritonitis, the diagnosis of absence seizures can be overlooked when only one test is done and the results are not accurate. If you suspect your child has a seizure disorder, be sure to ask about the multiple tests that can be done and recognize that an EEG may not always produce an accurate positive finding.

An EEG, also known as an electroencephalography, is a type of medical test done, in a series of tests, to rule out or confirm the presence of a seizure disorder. Because the EEG is designed to monitor for brain wave activity, there are some forms of seizures the test may not detect. Unless your child has some form of physical, neurological change of brain waves that can be detected, the simple loss of consciousness will go unnoticed on the EEG test.

Most neurologists rely heavily upon the EEG for diagnosing a child with absence seizures. It is important, however, that you ask for the variety of other tests that can be performed, including mental health evaluation, to rule out other conditions before accepting absence seizures as the diagnosis. For many children, the diagnosis will come only as a result of ruling out other, more obvious, conditions.

Like many types of medical tests, no one test can provide a full proof and accurate result. If your child is showing signs of a seizure disorder you can expect that an EEG will need to be performed. Often, however, some types of seizure disorders are not readily visible on an EEG and, as a result, the diagnosis may be incorrect. Always be familiar with the testing and understand, as outlined, by EEG's may not provide the best medical test outcome.

Sources: Handbook of EEG Interpretation, by Dr. William Tatum