An ambulatory electroencephalogram (AEEG) records the brain’s electrical activity over an extended period, typically 24 to 72 hours, while the patient is outside of a clinical environment. This portability allows healthcare providers to capture activity, such as seizures or unusual brainwave patterns, that might not appear during a brief in-office session. The success of this monitoring depends on maintaining the integrity of the recording equipment and the signal quality. Therefore, specific actions must be avoided to ensure the collected data is accurate and useful for diagnosis.
Restrictions on Water and Hygiene
Patients must completely avoid water exposure to the head and electrode setup throughout the entire recording period. Water is a conductor that can short-circuit the electrical connections between the scalp and the recording device. The conductive paste or gel used to secure the electrodes degrades rapidly when wet, leading to signal loss or high impedance readings. This degradation renders the recorded data unreliable or unusable for clinical interpretation.
Prohibitions extend beyond traditional bathing; patients must not take showers, immerse themselves in bathtubs, or enter swimming pools, oceans, or hot tubs. Secondary sources of moisture, such as heavy steam from saunas or prolonged exposure to rain, should also be strictly avoided. Even slight moisture accumulation can compromise the electrode-skin interface.
The application of hair products near the electrodes is also prohibited during the test. Products like hair sprays, gels, oils, and conditioners create a barrier between the electrode and the scalp, interfering with the connection. These substances can also contaminate the electrode gel, increasing electrical resistance and resulting in artifacts. Patients should utilize sponge baths to maintain hygiene, carefully avoiding wetting the head and the attached equipment.
High-Impact Activities and Movement to Avoid
Patients must refrain from engaging in any vigorous physical activity, including running, heavy lifting, competitive sports, or intense exercise. These actions lead to excessive perspiration, which introduces moisture and salt onto the scalp. The salt in sweat is corrosive and can rapidly degrade the electrode metal, while the moisture changes the conductivity properties of the skin surface.
This influx of moisture and electrolytes generates significant motion artifacts, appearing as large, rhythmic spikes in the EEG recording. These artifacts can mask the subtle brain activity the test is designed to capture, making the data indistinguishable from noise. The resulting data is often discarded, requiring the entire monitoring period to be repeated.
Activities involving rapid or forceful head movements, such as jumping or shaking, should also be avoided as they mechanically stress the electrode attachments. Any action that causes friction or rubbing against the cap, such as drying hair roughly near the site, risks loosening the contact points. A loose electrode generates a continuous, high-amplitude artifact that prevents accurate interpretation of that channel.
Patients must be cautious about sleeping positions that place direct pressure on the recording equipment or electrode sites. Lying on the side or back in a way that presses the head against a hard surface can compress the electrodes, causing discomfort and generating pressure-related artifacts. Excessive compression risks dislodging the electrode entirely or damaging the wires connecting it to the recorder box.
Manipulating the Electrodes and Wiring
It is strictly prohibited to touch, scratch, or rub the electrodes or the surrounding scalp area. Manipulation of the application site, even minor scratching due to irritation, can alter the precise contact point necessary for stable signal acquisition. This action often introduces static electricity and movement artifacts directly into the recording channels.
Patients must avoid pulling, tugging, or excessively bending the wires that run from the electrodes to the recorder unit. The wires are delicate and are positioned to minimize strain and movement artifacts during normal daily activities. Applying undue tension or sharply bending the cables can compromise the internal wiring, leading to intermittent signal drop-outs or permanent channel failure.
Never attempt to open the recording box, adjust any settings, press buttons, or tamper with the battery compartment. The device is calibrated and sealed by the technician to ensure continuous, uninterrupted data collection. If an electrode feels loose or falls off, the patient must not attempt to reattach it. Instead, they should immediately contact the monitoring technician for guidance or a repair appointment.
Environmental Factors That Distort the EEG Signal
Patients must avoid proximity to powerful sources of electromagnetic fields (EMF), as these introduce significant electrical noise into the sensitive EEG recording. Large industrial machinery, poorly shielded electrical panels, and high-voltage power lines emit strong fields that can overwhelm the subtle brain signals. Exposure to these environments risks generating large, sustained 60-Hertz line noise artifacts across all channels.
Placing the recording box directly next to certain high-power electronic devices should be avoided. Older cathode ray tube (CRT) monitors, large unshielded speakers, and powerful magnets found in some household items emit disruptive magnetic fields. The recorder unit should be kept separate from these items to ensure the integrity of the stored data.
Exposure to extreme temperatures, both hot and cold, must be prevented, as this affects the function of the equipment. Sitting directly in front of a powerful heater or using a hair dryer near the cap can cause overheating, affecting the device’s internal circuitry and electrode integrity. Prolonged exposure to severe cold can also impact battery life and the performance of the electronic components.