An electroencephalogram (EEG) is a test that measures brain activity. Since its invention 100 years ago, healthcare teams have used EEGs to diagnose seizures and other brain conditions. If you or a loved one needs an EEG, here’s everything you can expect from this test, including tips to prepare. During drowsiness, the first discernible change is gradual loss of the frequent muscle and movement artifacts and reduction of blinks and rapid lateral eye movements. Instead, a very slow frequency of 0.25 to 1.0 Hz in the frontal and lateral frontal channels emerges. The EEG during drowsiness contains slower, synchronous frequencies of theta and delta throughout the background (see Figure 14).
Your hair and skin may feel sticky from the glue or paste that kept the electrodes in place during your EEG, so you may want to wash your hair when you get home. During an EEG, a technician places small metal disks (electrodes) on your scalp. The electrodes attach to a machine that monitors the electrical signals that your brain cells (neurons) make to communicate with each other.
Next, the technician will attach the electrodes to your head, around 16 to 25 in total. They may gently scrub each area where an electrode will be placed with a cream that’s mildly abrasive. This helps the disc stick better and also improves the quality of the recording. When you check in for your routine EEG test, you will probably be asked to sign a consent form.
An electroencephalogram (EEG) is a test that measures the electrical activity in the brain. An abnormal EEG result indicates unusual patterns of brain waves, which could be a sign of various neurological disorders. These abnormalities can help doctors diagnose conditions such as epilepsy, sleep disorders, and brain injuries.
Lambda is elicited by pattern viewing, having the configuration of the Greek letter lambda (Λ) and is a surface positive, occipitally predominant waveform. The EEG shows patterns of normal or abnormal brain electrical activity. Some abnormal patterns may occur with a number of different conditions, not just seizures. For example, certain types of waves may be seen after head trauma, stroke, brain tumor, or seizures. A common example of this type is called “slowing,” in which the rhythm of the brain waves is slower than would be expected for the patient’s age and level of alertness. Focal slow wave activity on the EEG is indicative of focal cerebral pathology of the underlying brain region.
Hyperventilation is also commonly induced during an EEG to produce abnormalities. Some people may not be able to hyperventilate safely, such as people with a history of stroke, asthma, or sickle cell anemia. When someone has epilepsy or another seizure disorder, there’s a small risk that the stimuli presented during the test (such as a flashing light) may cause a seizure. The technician performing the EEG is trained to safely manage any situation that might occur. When someone is in a coma, an EEG may be performed to determine their level of brain activity.
Causes of Abnormal EEG Results
If you’re being tested in a hospital for a longer time and are at risk of having severe seizures, other precautions can be taken. For example, a belt can be placed around your waist to keep you from falling and you may not be allowed to walk around. In rare cases, an EEG can cause seizures in a person with a seizure disorder. In these cases, the seizures are brought on by deep breathing or flashing lights.
There are several factors that can lead to abnormal EEG results. One common cause is epilepsy, a condition characterized by recurrent seizures. Other possible causes include brain tumors, stroke, infections, and genetic disorders. It is essential to consult with a healthcare professional to determine the underlying cause of the abnormal EEG findings.
Interpreting Abnormal EEG Results
When reviewing an abnormal EEG report, healthcare providers look for specific patterns that may indicate a neurological disorder. These patterns can help determine the type and severity of the condition, guiding the treatment plan. It is crucial to follow up with a neurologist or other specialists to discuss the implications of abnormal EEG results and develop a comprehensive care plan.
