An ambulatory electroencephalogram (EEG) is a study of brain activity conducted by sending a patient home wearing electrodes on the skull and carrying a recording device. Patients experiencing epilepsy and other neurological problems often have intermittent symptoms, and doing an ambulatory EEG increases the chances of recording the brain when something is happening. It is much less expensive than a study where a patient reports to a clinic and stays overnight or for several days, and is also less intrusive for the patient, as people can engage in regular activities during the test and are in fact encouraged to do so.
When people complain of seizures or other neurological symptoms, an EEG study can be done in a hospital to see if there is anything abnormal happening in the patient's brain, but the results of the study may be variable, as it only records for 20 to 40 minutes. For an ambulatory EEG, a technician glues electrodes to the head with collodion, a strong and durable glue, attaches leads, and clips the leads to a recorder to pick up data. People do not need to have their heads shaved for the test, and the skull is usually covered in a net cap for protection.
While undergoing an ambulatory EEG, patients should take medications normally and engage in all the activities they regularly do, including working, going to school, and so forth. Exercise is usually safe, unless it involves getting wet, as the recording device cannot be exposed to water. Patients can wipe down their bodies with a wet washcloth, but should avoid tubs, showers, and saunas during the ambulatory EEG to avoid damaging the machine.
Usually, people are asked to keep an activity diary. This can be matched up with the machine's output later to see if seizures are associated with particular triggers like activities or foods. The device also usually has what is known as an “event button.” When a patient experiences a seizure or another neurological abnormality, the button can be pushed to flag it in the machine's record, drawing the doctor's attention to the patient's brain activity at that point in time.
The ambulatory EEG can last between 24 and 72 hours, depending on the patient. At the end of the test, the patient goes back to the hospital so the electrodes can be removed and the data can be retrieved. A doctor will discuss the results with the patient after having time to review them.
