Diagnosis
Diagnosing Epilepsy
Diagnosing epilepsy is a multi-step process, usually involving the following evaluations:
Confirmation through patient history, neurological exam and supporting blood and other clinical tests that the patient has epileptic seizures and not some other type of episode such as fainting, breath-holding (in children), transient ischemic attacks, hypoglycemia or non-epileptic seizures.
Identification of the type of seizure involved.
Determination of whether the seizure disorder falls within a recognized syndrome.
A clinical evaluation in search of the cause of the epilepsy.
Based on all previous findings, selection of the most appropriate therapy.
Provide Information to Help the Doctor
If you have had a seizure and you seek medical help, your doctor will want to know:
Was the seizure caused by a short-term problem (like fever or infection) that can be corrected?
Was it caused by a continuing problem in the way your brain's electrical system works?
Is there anything about the structure of your brain that could cause seizures?
Was the seizure an isolated event, or does it mean that you have epilepsy?
Diagnostic Methods and Tools
The doctor's main tool in diagnosing epilepsy is a careful medical history with as much information as possible about what the seizures looked like and what happened just before they began. The doctor will also perform a thorough physical examination, especially of the nervous system, as well as analysis of blood and other bodily fluids.
A second battery of diagnostic tools includes an electroencephalograph (EEG). This is a machine that records brain waves picked up by tiny wires taped to the head. Electrical signals from brain cells are recorded as wavy lines by the machine. Brain waves during or between seizures may show special patterns which help the doctor decide whether or not someone has epilepsy.
Imaging methods such as CT (computerized tomography) or MRI (magnetic resonance imaging) scans may be used to search for any growths, scars or other physical conditions in the brain that may be causing the seizures. In a few research centers, positron emission tomography (PET) imaging is used to identify areas of the brain which are producing seizures.
Which tests and how many of them are ordered may vary, depending on how much each test reveals.
The Treatment Decision
'The decision to treat is highly individualized, weighing the risks of treatment against the risks of seizures.'
When a child or adult experiences a single seizure, or appears at the doctor’s office with a history of questionable events that may or may not have been seizures, the first issue is to determine what happened, whether a seizure actually took place, of what type and duration it was, the possible cause, and the future prognosis.
Once this information is gathered, the next question is whether to treat the underlying condition (if one has been identified and if it is treatable), or whether to treat the symptoms by prescribing antiepileptic (or seizure-preventing) drugs.
Unless the EEG is clearly abnormal, thus increasing the likelihood of subsequent seizures, physicians tend to wait until a second or even third seizure occurs before beginning antiepileptic medication. They do so because studies show that an otherwise normal child who has had a single seizure has a relatively low (15 percent) risk of a second one. Once the second has occurred, the risk of subsequent seizures is substantially increased.
On the other hand, the risk of another seizure for a child who is neurologically abnormal, or whose EEG is abnormal, may be as high as 50 to 60 percent.
In determining whether to treat, physicians consider the risk-benefit ratio, which varies according to the age of the patient and his or her activity level. Waiting to see whether another generalized tonic-clonic seizure occurs is less risky for a child living in a sheltered home environment than it is for a salesman who lives most of his life driving a car, or an elderly person with brittle bones. On the other hand, antiepileptic drugs have side effects which, while generally mild, can in some cases include liver damage and potentially fatal rashes and blood disorders. Thus the decision to treat becomes a highly individualized one in which the risks of the treatment are weighed against the risks of the seizures.
There is debate about whether or not children with febrile (fever caused) seizures should be placed on antiepileptic drugs. Current opinion favors withholding therapy for most of these children, since side effects of the medication may cause more problems than recurrent febrile convulsions. There may be instances, however, when treatment is prescribed.
Factors Influencing Decision to Treat
- Abnormal EEG
- Previous Seizure
- Person Drives
- Other Neurological Impairment
- Elderly
Factors Influencing Decision Not to Treat
- Single Seizure
- No History
- Neurologically Normal
- Young Age
- Side Effects
Definitions:
Computerized tomography (CT): A scanning method that uses X-rays and computers to create images of the internal structure of the brain, produced at different levels, in a series of slices.
Magnetic resonance imaging (MRI): An imaging method using magnets instead of X-rays. Produces detailed pictures of the internal structure of the brain.
