A 24-hour ambulatory electroencephalogram (AEEG) is used to record EEG tracings on a cassette or digital recorder on a continuous outpatient basis. Electrodes for at least 3 recording channels are secured to the patient's head while a digital or cassette recorder is secured to the patient's waist or to a shoulder harness. The EEG information is stored for later play back and analysis. A CMS National Coverage Determination (NCD) states that ambulatory EEG should always be preceded by a resting EEG.

The advantage of 24-hour AEEG is its ability to continuously record over a prolonged period both general and localized seizure activity during near-normal activity. Recent advances in computer technology have improved available capabilities of AEEG monitors. Lighter weight, smaller, and faster processors with larger digital storage capacity have overcome earlier limitations on EEG recording and analysis. Commercially available AEEG has evolved during the last 2 decades from 3-channel analog devices to digital machines with reformable montages of up to 32 channels and computer-assisted spike and seizure detection programs.

Ambulatory EEG monitoring may facilitate the differential diagnosis between seizures and syncopal attacks, sleep apnea, cardiac arrhythmias or hysterical episodes. The test may also allow the investigator to identify the epileptic nature of some episodic periods of disturbed consciousness, mild confusion, or peculiar behavior, where resting EEG is not conclusive. It may be useful in documenting seizures that are precipitated by naturally occurring cyclic events or environmental stimuli, which are not reproducible in the hospital or clinic setting. It may also allow an estimate of seizure frequency, which may at times help to evaluate the effectiveness of a drug and determine its appropriate dosage.

Ambulatory monitoring, however, is not necessary to evaluate most seizures, which are usually readily diagnosed by routine EEG studies and history.

Combined Use of Ambulatory EEG and Home-Video Recording

Lawley et al (2015) stated that EEG is an established diagnostic tool with important implications for the clinical management of patients with epilepsy or non-epileptic attack disorder. Different types of long-term EEG recording strategies have been developed over the last decades, including the widespread use of AEEG, which holds great potential in terms of both clinical usefulness and cost-effectiveness. These investigators presented the results of a systematic review of the scientific literature on the use of AEEG in the diagnosis of epilepsy and non-epileptic attacks in adult patients. Taken together, these findings confirmed that AEEG is an useful diagnostic tool in patients with equivocal findings on routine EEG studies and influenced management decisions in the majority of studies. There is evidence that AEEG is also more likely to capture events than sleep-deprived EEG; however, there are currently insufficient data available to compare the diagnostic utility of modern AEEG technology with inpatient video-telemetry. The authors concluded that further research on the combined use of AEEG and home-video recording is needed.

Scope of Policy

This Clinical Policy Bulletin addresses ambulatory electroencephalography.

Medical Necessity

Aetna considers ambulatory electroencephalography (EEG) with or without home video monitoring medically necessary for

of the following conditions, where the member has had a recent (within the past 12 months) neurologic examination and standard EEG studies

:

Aetna considers the combined use of ambulatory EEG and home-video recording an equally acceptable medically necessary alternative to ambulatory EEG alone.

Aetna considers ambulatory EEG experimental and investigational for all other indications because of insufficient evidence in the peer-reviewed literature.

Duration of Monitoring

The goal of ambulatory EEG is usually achieved within 48 hours. Ambulatory EEG monitoring for longer than 7 days may be reviewed for medical necessity.