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Making the correct diagnosis is a very important part of choosing the right treatment to control seizures.
Diagnosing epilepsy can be hard. When you talk with a doctor after you've had unexplained seizures, you and the doctor will work together to answer three questions:
Was the event a seizure? Or was it something that looked like a seizure? Some other conditions can appear to be seizures but aren't seizures. (These might include breath-holding spells, migraine headaches, muscle twitches or tics, sleep disorders, or psychogenic seizures.) Taking medicines to treat epileptic seizures if your seizures aren't epileptic can expose you to unneeded risks.
If you are having seizures, are the seizures caused by epilepsy? Not everyone who has a seizure has epilepsy. The seizure may have been caused by something else, such as a fever, certain medicines, an electrolyte imbalance, or breathing in fumes. Taking antiepileptic medicines when you don't have epilepsy may put you at unneeded risk from possible side effects.
If you have or may have epilepsy, what types of seizures are you having? The different types of seizures (partial and generalized) aren't treated in the same way or with the same medicines. For example, some medicines that control complex partial seizures may make absence seizures worse.
A physical exam and your detailed medical history often give the best clues as to whether you have epilepsy and what type of epilepsy and seizures you have. Talking about what happens to you just before, during, and right after a seizure can help the doctor make a diagnosis.
Your doctor may want to use lab tests to rule out other possible causes for the seizures. These tests may include:
Complete blood count (CBC). This test can check for infection.
Blood chemistry tests. These tests check for abnormal electrolyte levels (like magnesium, sodium, and calcium), signs of kidney or liver malfunction, and other common problems.
Lumbar puncture (sometimes called a spinal tap). This test collects spinal fluid so it can be checked to rule out infections, like meningitis and encephalitis.
Toxicology screen. This test checks blood, urine, or hair to look for poisons, illegal drugs, or other toxins.
Your doctor may do other tests such as:
Electroencephalogram (EEG). This is the most useful test for supporting a diagnosis of epilepsy. A computer records your brain's electrical patterns as wavy lines. If you have epilepsy, the EEG may show abnormal spikes or waves in your brain's electrical activity patterns. Different types of epilepsy cause different patterns. But an EEG is limited in its ability to diagnose epilepsy. And many people with epilepsy have normal EEGs in between seizures.
Imaging tests. An MRI and a CT scan are imaging tests that allow a doctor to view the brain. The doctor can evaluate the cause and location of a possible source of epilepsy within the brain. The scans can show scar tissue, tumors, or structural problems in the brain that may be the cause of seizures or epilepsy. An MRI is the more helpful test in most cases. Imaging tests may not be done after a first seizure. But they are recommended in many situations (such as after a first seizure in adults or after a head injury).
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