brain, spinal cord, and nerve disorders
Seizure Disorders
Diagnosis of Seizure Disorders
A doctor's evaluation If the person has never had a seizure before, blood and other tests, imaging of the brain, and usually electroencephalography If a seizure disorder has already been diagnosed, usually blood tests to measure levels of antiseizure medications The diagnosis of a seizure is based on symptoms and the observations of eyewitnesses. Symptoms that suggest a seizure include loss of consciousness, muscle spasms that shake the body, a bitten tongue, loss of bladder control, sudden confusion, and inability to pay attention. Doctors diagnose a seizure disorder (epilepsy) when people have at least two unprovoked seizures that occur at different times. People who lose consciousness, sometimes even when they lose muscle tone and muscles jerk, may not be having a seizure. A brief loss of consciousness is more likely to be Fainting (syncope) than a seizure. People are usually evaluated in an emergency department. If a seizure disorder has already been diagnosed and people have completely recovered, they may be evaluated in a doctor’s office. An eyewitness report of the episode can be very helpful to doctors. An eyewitness can describe exactly what happened, whereas people who have an episode usually cannot. Doctors need to have an accurate description, including the following: How fast the episode started Whether it involved abnormal muscle movements (such as spasms of the head, neck, or facial muscles), tongue biting, drooling, loss of bladder or bowel control, or muscle stiffening How long it lasted How quickly the person recovered A quick recovery suggests fainting rather than a seizure. Confusion that lasts for many minutes to hours after consciousness is regained suggests a seizure. Although eyewitnesses may be too frightened during the seizure to remember all details, whatever they can remember can help. If possible, how long a seizure lasts should be timed with a watch or other device. Seizures that last only 1 or 2 minutes can seem to go on forever. Doctors also need to know what people experienced before the episode: whether they had a premonition or warning that something unusual was about to happen and whether anything, such as certain sounds or flashing lights, seemed to trigger the episode. Doctors ask people about possible causes of seizures, such as the following: Whether people have had a disorder that can cause seizures (such as a Overview of Brain Infections ) or a Which medications or illicit drugs they are using or have recently stopped Whether they are consuming alcohol or have recently stopped For people who are taking medications to control seizures, whether they are taking the medications as directed Whether they are getting enough sleep (not getting enough sleep can make seizures more likely to occur in some people) With children, whether they have relatives who also have seizures A thorough physical examination is done. It may provide clues to the cause of the symptoms. Once a seizure is diagnosed, more tests are usually needed to identify the cause. People known to have a seizure disorder may not need tests, except for a blood test to measure the levels of the antiseizure medications they are taking. However, if they have symptoms that suggest a disorder that can be treated (such as a head injury or an infection), more tests are done. Blood tests are often done to check for possible causes of a seizure or to find out why a seizure may have occurred in someone with a known seizure disorder. These tests include measurement of the levels of substances such as sugar, calcium, sodium, and magnesium and tests to determine whether the liver and kidneys are functioning normally. A sample of urine may be analyzed to check for illicit drugs that may not be reported. Such drugs can trigger a seizure. Electrocardiography may be done to check for an Imaging Tests is usually done promptly to check for If doctors suspect a brain infection such as meningitis or encephalitis, a Spinal Tap (lumbar puncture) is usually done. Electroencephalography (EEG) can help confirm the diagnosis. EEG is a painless, safe procedure that records electrical activity in the brain. Doctors examine the recording (electroencephalogram) for evidence of abnormal electrical discharges. Because the recording time is limited, EEG can miss abnormalities, and results may be normal, even in people who have a seizure disorder. EEG is sometimes scheduled after people have been deprived of sleep for 18 to 24 hours because lack of sleep makes abnormal discharges more likely to occur. An electroencephalogram (an EEG) is a recording of the brain’s electrical activity. The procedure is simple and painless. About 20 small adhesive electrodes are placed on the scalp, and the brain’s activity is recorded under normal conditions. Then the person is exposed to various stimuli, such as bright or flashing lights, to try to provoke a seizure. During a seizure, electrical activity in the brain accelerates, producing a jagged wave pattern. Such recordings of brain waves help identify a seizure disorder. Different types of seizures have different wave patterns. EEG may be repeated because when done a second or even a third time, it may detect seizure activity and sometimes help identify the type of seizure. This information may have been missed the first time the test was done. If the diagnosis is still uncertain, specialized tests, such as video-EEG monitoring, can be done at an epilepsy center. Forvideo-EEG monitoring,people are admitted to a hospital for 2 to 7 days, and EEG is done while they are video-taped. If people are taking an antiseizure medication, it is often stopped to increase the likelihood of a seizure. If a seizure occurs, doctors compare the EEG recording with the video recording of the seizure. They may then be able to identify the type of seizure and the area of the brain where the seizure began. Ambulatory EEGenables doctors to record brain activity for days at a time—while people are at home. It may be useful if seizures recur in people who cannot be admitted to the hospital for a long time. 