An electroencephalogram (EEG) measures the brain’s electrical activity using small metal discs, or electrodes, placed on the scalp. This traditional test captures a brief snapshot of brain function, often lasting only 20 to 40 minutes. Video EEG monitoring (VEEG) is a specialized, long-term version that incorporates continuous video and audio recording of the patient. This combination provides a powerful diagnostic tool by allowing physicians to correlate internal electrical events in the brain with the patient’s external physical behavior. The test is highly effective for capturing intermittent neurological events that might be missed during a routine, short-duration EEG.
Defining Video EEG Monitoring
Video EEG monitoring simultaneously captures brain waves and observable clinical signs over an extended period. The EEG portion records the electrical signals generated by neurons, which appear as characteristic wave patterns. Doctors look for abnormal bursts of energy that interrupt these patterns to identify neurological disorders. The video component provides a visual record of the patient’s movements, facial expressions, and sounds made during an event.
This dual-recording system time-locks the patient’s physical symptoms with the corresponding brain activity. This correlation is crucial for distinguishing between events caused by abnormal brain activity and those with a non-neurological origin. The video and EEG data are transmitted to a computer, where they are continuously monitored and stored for detailed analysis.
Conditions Diagnosed with Video EEG
The purpose of Video EEG monitoring is to identify and characterize paroxysmal clinical events, which are symptoms that occur suddenly and unpredictably. The test is frequently used to determine if a patient’s spells are caused by epilepsy, which involves abnormal electrical discharges in the brain. It is the most effective method for recording epileptiform activity and seizures, especially when they are infrequent or difficult to classify.
VEEG helps precisely locate the area of the brain where seizures originate, which is a step often necessary for surgical planning in cases of drug-resistant epilepsy. Monitoring is also instrumental in differentiating true epileptic seizures from non-epileptic events that can mimic them. These non-epileptic events include psychogenic non-epileptic attacks (PNEAs), syncope (fainting), certain sleep disorders like parasomnias, and movement disorders. By capturing the event, the VEEG provides the definitive evidence needed for an accurate diagnosis and appropriate treatment.
Preparing for the Monitoring Period
Patient preparation begins before hospital admission to ensure high-quality data collection. Patients must wash their hair with only shampoo the night before or morning of the test, avoiding conditioners, oils, gels, or hairsprays. Residue from these products interferes with electrode adherence and conductivity.
If the patient has an established seizure medication regimen, a physician may instruct them to taper or stop certain anti-epileptic drugs before the stay to increase the likelihood of capturing an event. Patients should plan for a hospital stay, typically remaining in the monitoring unit for several days. Comfortable, loose-fitting clothing is recommended, especially shirts that button or zip up the front, since garments pulled over the head cannot be worn once electrodes are secured.
Logistical items should be brought to pass the time, as activity is restricted to the camera’s view. All routine medications must be brought in their original, labeled containers. Any specific dietary requirements should also be communicated to the medical team.
The Monitoring Process and Duration
Upon admission, a trained technologist applies between 13 and 25 small metal electrodes to the patient’s scalp using a conductive paste or strong adhesive. The electrodes are secured with a head dressing and connected by wires to a portable transmitter. This transmitter continuously sends the brain wave data to a computerized recording system located outside the room. The patient is housed in a private room, usually within a specialized Epilepsy Monitoring Unit (EMU), where a fixed camera and microphone capture all activity.
The length of the monitoring period varies depending on how often a patient typically experiences their events, but it commonly lasts between three and seven days. The primary goal is to record at least one of the patient’s typical events to establish a correlation between the physical manifestation and the electrical activity. To encourage an event to occur, the physician may safely adjust or reduce seizure medications under close supervision.
The medical team may also employ “activation procedures” like sleep deprivation or photic stimulation (flashing lights) to trigger an event, which is only done when deemed safe. Throughout the stay, a patient may be asked to press a bedside button to mark the EEG tracing when they feel an event starting, alerting the staff to observe and document the symptoms in real-time.