What are the protocols for Ambulatory Electroencephalogram (EEG)?

From the Guidelines

Ambulatory EEG protocols should prioritize continuous monitoring of brain activity for 24-72 hours to capture intermittent events and provide insight into daily activities and sleep-wake cycles, as this approach offers advantages over standard EEG in detecting seizures and correlating brain activity with reported symptoms. When implementing ambulatory EEG protocols, it is essential to consider the recommendations from the international multidisciplinary consensus conference on multimodality monitoring in neurocritical care, which suggests the use of EEG to detect seizures, including nonconvulsive seizures, in patients with altered mental status or unexplained neurological deficits 1. The protocol typically involves electrode placement using collodion glue or paste to secure 16-24 electrodes to the scalp in the international 10-20 system configuration. Patients should wear a small recording device that stores data on a memory card and maintain a detailed activity log noting seizure events, symptoms, sleep times, and medication intake. During the monitoring period, patients should continue their prescribed antiepileptic medications unless specifically instructed otherwise by their neurologist, as medication withdrawal may be part of the protocol to provoke seizure activity in certain cases 1. Some key points to consider when implementing ambulatory EEG protocols include:

• Patients should avoid showering but can perform sponge baths carefully to prevent electrode displacement
• Common seizure-provoking activities such as sleep deprivation, hyperventilation, photic stimulation, or emotional stress may be recommended to increase the likelihood of capturing events
• After monitoring completion, the electrodes are removed, and the data is analyzed by a neurologist to correlate brain activity with reported symptoms It is crucial to note that the evidence supporting the benefit of continuous over routine EEG recordings is limited, but the use of ambulatory EEG protocols can provide valuable information about brain electrical activity and help detect seizures, including nonconvulsive seizures, in patients with altered mental status or unexplained neurological deficits 1.

From the Research

Ambulatory EEG Protocols

• Ambulatory EEG (AEEG) devices offer portable, multichannel, digital EEG recording with or without video in the patient's natural environment 2
• The technology applied for AEEG recording is like the technology for routine EEG and inpatient long-term video-EEG monitoring but designed to be compact and wearable 2
• AEEG is a monitoring technique that allows the recording of continuous EEG activity when patients are at home, without the necessity of admission to the hospital for prolonged video-EEG monitoring 3

Diagnostic Yield of Ambulatory EEG

• The yield of AEEG was assessed by taking into account the questions asked by the clinician before and after the investigation, with a diagnostic yield of 72% in one study 3
• AEEG has a high diagnostic yield and is believed that careful selection of patients is the most important factor for a high diagnostic yield 3
• The main use of AEEG is the characterization of patients with non-epileptic events, in patients with a diagnosis of epilepsy that is not clear, and quantification of spikes and seizures to improve the medical management 3

Comparison with Routine EEG

• Ambulatory EEG captured interictal epileptiform discharges (IEDs)/seizures with a sensitivity of 72%, compared with 11% for the first routine EEG and 22% for the second routine EEG 4
• The diagnostic performance of the AEEG was statistically better compared with the first routine EEG and second routine EEG 4
• AEEG is a cost-effective solution for increasing demands for in-hospital video-EEG monitoring of adult patients 3

Interpretation and Reviewing of Ambulatory EEG

• AEEGs are clinically interpreted based on a best practices approach and can be modified to address recording problems that, until recently, have been approached only in an epilepsy monitoring unit environment 5
• The qualifications necessary for the proper interpretation and reporting of AEEG studies include expertise in EEG interpretation and epilepsy diagnosis 5
• AEEG recordings can be integrated into the care of complex clinical situations that are frequently encountered not only by the practicing generalists but also by epilepsy specialists who practice out of a comprehensive epilepsy program 5