Long-term electroencephalography (EEG) monitoring records the brain’s electrical activity over an extended period. This non-invasive test involves placing small sensors on the scalp that detect brain waves. Unlike a standard, brief EEG, long-term monitoring captures subtle or infrequent brain activity patterns that might not appear during a shorter session. Its purpose is to provide a comprehensive look at brain function over time, aiding in the diagnosis and management of various neurological conditions.
Why It’s Performed
Long-term EEG monitoring is performed to investigate recurrent neurological events difficult to capture during a brief clinical visit. A primary reason for this extended recording is to diagnose and characterize epilepsy. By continuously monitoring brain activity, clinicians can identify the specific type of seizure, differentiate between focal and generalized seizures, and pinpoint their origin. This detailed information guides treatment decisions, including medication selection or surgical interventions.
The monitoring also helps evaluate the effectiveness of anti-seizure medications, showing if adjustments are needed. Beyond epilepsy, long-term EEG investigates unexplained blackouts or episodes of altered consciousness. It helps distinguish between epileptic seizures and other conditions that can cause similar symptoms, such as syncope or psychogenic non-epileptic seizures, which are not caused by abnormal electrical activity. Identifying the cause of these events is important for proper management.
Long-term EEG also assists in diagnosing certain sleep disorders, especially when nocturnal seizures or other sleep-related disturbances are suspected. The extended recording period is beneficial because many neurological events, especially seizures, are unpredictable and may occur infrequently. A short, standard EEG might miss these sporadic events, making prolonged observation necessary for accurate diagnosis.
How Long-Term EEG Monitoring Works
Long-term EEG monitoring begins with the placement of small electrodes onto the scalp using a conductive paste or gel. These electrodes are positioned according to the 10-20 system to cover different regions of the brain. Wires connect these electrodes to a compact, portable recording device that continuously captures the brain’s electrical signals. This device is typically worn in a pouch around the patient’s waist or neck.
Long-term EEG monitoring occurs in two main settings. Inpatient monitoring, often called Video-EEG Monitoring, takes place in a hospital or specialized epilepsy monitoring unit. Here, brain activity is simultaneously recorded with video footage of physical movements and behaviors. This allows neurologists to correlate electrical patterns with observable symptoms or events, providing a comprehensive view of what happens during an episode. Patients remain in a controlled environment, often for several days, allowing for observation during wakefulness and sleep.
Outpatient or ambulatory long-term EEG monitoring allows patients to wear the portable recording device while going about daily activities at home. This approach is beneficial for capturing events more likely to occur in a natural environment. The duration of monitoring varies, ranging from 24 to 72 hours for ambulatory studies, to several days or weeks for inpatient video-EEG, especially for infrequent events or medication changes. The consistent recording of brain waves provides extensive data for neurological analysis.
Preparing for and Living with Long-Term EEG
Preparing for long-term EEG monitoring involves steps to ensure optimal recording quality. Patients are advised to wash their hair thoroughly the night before or morning of the procedure, using only shampoo and avoiding conditioners, hair sprays, gels, or other styling products. Clean hair allows electrodes to adhere effectively and ensures better signal transmission. It is also helpful to wear comfortable, loose-fitting clothing that allows easy access to the scalp for electrode placement.
Once electrodes are applied and the recording device is secured, daily life during monitoring requires adjustments. Patients must be careful not to pull on or dislodge the electrodes, which are typically held in place with medical glue or tape. Activities involving getting the electrodes wet, such as showering, bathing, or swimming, are not permitted during the monitoring period to protect the equipment and maintain electrode connections. Strenuous exercise or activities that could lead to excessive sweating should also be avoided, as sweat can interfere with electrical signals.
Patients are instructed to keep a detailed diary or log of any symptoms, sensations, or events they experience, noting the precise time of occurrence. This diary helps the neurologist correlate the patient’s experiences with brain wave data. After the monitoring period is complete, a technician removes the electrodes and cleans any remaining paste from the scalp. The recorded data is analyzed by a neurologist, and results are shared with the patient and their referring physician within days to weeks, depending on the recording’s complexity.