Description
The brain is created by the structural and functional properties of interconnected neurons or brain cells. Neurons communicate with each other by electrical changes. These electrical changes can be seen in the form of brain waves, shown in an electroencephalogram (EEG). Variations in the brain wave characteristics correlate with some neurological conditions. EEGs are used to diagnose specific medical conditions, such as suspected seizures or seizures associated with epilepsy.

Various ictal (during a seizure, stroke, headache) and interictal (period between seizures) EEG patterns correspond to specific seizure types and types of epilepsy. While the EEG is almost always abnormal during a seizure, it may be normal between seizures. Thus, lack of interictal EEG abnormalities does not exclude a diagnosis of epilepsy. However, at some time, most epilepsy patients have abnormal EEG discharges. In contrast, some persons with EEG'S that show epilepsy-like activity never have seizures. Thus, physicians interpret EEG results within the context of other information they are gathering. Apart from the patient history and the neurological exam, the EEG is the most influential tool in the diagnosis of seizures and epilepsy.¹

Background
In resting/conventional surface/scalp EEG, the recording is obtained by placing electrodes with at least 4 recording channels, on the scalp with a conductive gel or paste, usually after preparing the scalp area by light abrasion to reduce impedance due to dead skin cells. Many systems typically use electrodes, each of which is attached to an individual wire. Some systems use caps or nets into which electrodes are embedded; this is particularly common when high-density arrays of electrodes are needed.

A very low electrical current is sent through the electrodes and the baseline brain energy is recorded on a diagnostic machine. The electrical activity recording is analyzed through an audio amplifier system. Patients are then exposed to a variety of external stimuli, including bright or flashing light, noise or certain drugs, or are asked to open and close their eyes, or to change breathing patterns. The electrodes transmit the resulting changes in brain wave patterns. With identification and classification of brain waves, the analysis of data provides information useful in mapping the brain and various areas involved with body function in relation to disease status. Since movement and nervousness can change brain wave patterns, patients usually recline in a chair or on a bed during the test, which takes up to an hour. Testing for certain disorders may also require an EEG during sleep.

During the recording, a series of activation procedures may be used. These procedures may induce normal or abnormal EEG activity that might not otherwise be seen. These procedures include hyperventilation, photic stimulation (with a strobe light), eye closure, mental activity, sleep and sleep deprivation. During (inpatient) epilepsy monitoring, a patient's typical seizure medications may be withdrawn.

Ambulatory Electroencephalography (AEEG) Monitoring
AEEG or mobile EEG monitoring allows a prolonged EEG recording of the electrical current potential or brain activity through the skull, thru the same process as the conventional scalp/surface EEG. An AEEG has the ability to record continuously for up to 72 hours which increases the opportunity of recording an ictal event (during a seizure), or interictal (between seizures) epileptiform discharge.² This method of recording offers the ability to gather data on a long term, outpatient basis, with the option for some patients to be done at their home.

In the past decade, computer technology has enabled portable recording of up to 36 channels with sampling rates of up to 400 Hz (hertz). AEEG'S can be transmitted by telephone, in which the electrical brain activity is recorded and transmitted to an offsite center for analysis and reporting. The AEEG can also be transmitted by radio or wire in the diagnosis of complex seizure variants which require inpatient monitoring, but do not require the patient to be bed bound. Virtually all contemporary EEG recordings use digital recording methods. There are few, if any, paper analog EEG recordings carried out in current medical practice. There is a distinction between digital recording and digital analysis of EEG data:

• A digital recording uses a digital EEG recorder (machine); but it still involves visual analysis of the wave forms. It is digital to the extent that an analog, close-ended paper recorder is not used at the time of wave form (data) capture. This type of reading-by-eye represents the typical EEG interpretation in most clinical situations.
• A digital analysis requires the use of quantitative analytical techniques. Data selection, quantitative software processing and dipole source analysis are some of the techniques utilized.

Electroencephalogram Video (VEEG) Monitoring
VEEG monitoring is the simultaneous recording of the EEG and video monitoring of patient behavior, in an inpatient or outpatient setting. This allows for correlation of ictal and interictal electrical events with demonstrated or recorded seizure symptomology. The combined image of EEG tracings and visible behavior helps the physician diagnose the epilepsy and identify affected areas of the brain. Intensive closed-circuit TV and EEG monitoring of this type also helps distinguish between true epileptic seizures caused by electrical discharge and non-epileptic seizures caused by psychological factors. The EEG monitoring may be digitized.

Regulatory Status
There are numerous EEG devices that have been cleared for marketing by the U.S. Food and Drug Administration (FDA) under the guidance of the Center for Devices and Radiological Health (CDRH), under section 510(k) clearance process.

Today's EEG devices have many more features than the devices that were in existence at the creation of the first EEG product code, GWQ, in the late 1970s. Contemporary designs of EEG devices may include classic features, such as standard full-montage EEG acquisition systems or polysomnography devices, but they may also include more novel features, such as automatic event detection software or source localization software. There are 11 product codes that will allow CDRH to better distinguish among the different types of EEG devices marketed in the U.S. and more effectively regulate EEG devices in both the premarket and post-market settings.³

Policy 
Ambulatory Electroencephalogram (AEEG) Monitoring
AEEG monitoring may be considered MEDICALLY NECESSARY when used:

• To classify seizure type in individuals with epilepsy after a routine electroencephalogram (EEG) is non-diagnostic and classification will be used to select drug therapy.
• In conjunction with ambulatory electrocardiogram (ECG) recordings for seizures suspected to be of cardiogenic origin (i.e., cardiac arrhythmias, transient ischemic attacks, etc.) not diagnosed by conventional studies.
• To determine classification and quantification of seizures in a patient who experiences frequent absence or petit mal seizures.
• To determine characterization (lateralization, localization, distribution) of EEG abnormalities, both ictal (i.e., seizure, stroke, headache) and interictal (period between seizures), associated with seizure disorders in the evaluation of patients with intractable epilepsy for surgical evaluation.
• To monitor neonates with hypoxic-ischemic encephalopathy (HIE) who are being treated with therapeutic hypothermia (TH).

AEEG monitoring is considered NOT MEDICALLY NECESSARY when used in the following circumstances:

• Study of neonates who do not meet the criteria above, or unattended non-cooperative patients.
• Localization of seizure focus/foci when the seizure symptoms and/or other EEG recordings indicate the presence of bilateral foci or rapid generalization.
• For final evaluation of patients who are being considered as candidates for resective surgery when the medically necessary criteria listed above have not been met.

NOTE 1: In most circumstances extended AEEG monitoring (i.e., longer than 72 hours) is not necessary, as AEEG is generally diagnostic within the first 24 to 72 hours.

Electroencephalogram Video (VEEG) Monitoring

VEEG monitoring may be considered MEDICALLY NECESSARY:

• To diagnosis seizure type and epilepsy syndrome in individuals who present diagnostic difficulties following clinical assessment and standard EEG.
• For identification and localization of a seizure focus in individuals with intractable epilepsy who are being considered for surgery.
• To monitor neonates with HIE who are being treated with TH.
• To document provocation of seizures after medication withdrawal for the purpose of making medication adjustments or otherwise determining an appropriate treatment plan.

VEEG monitoring is considered NOT MEDICALLY NECESSARY for all other indications.

NOTE 2: In most circumstances, VEEG monitoring for an inpatient may continue 24 hours or more, to as many as 72 hours for long-term VEEG monitoring (LTM); whereas, outpatient may have a duration of 6 to 8 hours.

Digital Analysis of Electroencephalogram (DEEG)

DEEG is considered NOT MEDICALLY NECESSARY as there is no evidence that such additional processing and interpretation has been shown to improve outcomes in patient management.

NOTE 3: Digital analysis of an EEG is not the same as a digital recording of an EEG. Refer to the Description section for more information.

NOTE 4: This policy does not address resting/conventional EEGs.

Rationale 
The electroencephalogram (EEG) is a key tool in the diagnosis and management of epilepsy and other seizure disorders. It is also used to assist in the diagnosis of brain damage and disease (e.g., stroke, tumors, and encephalitis), mental retardation/intellectual disability, sleep disorders, degenerative diseases such as Alzheimer's disease and Parkinson's disease, and certain mental disorders (e.g., alcoholism, schizophrenia, and autism).

Literature suggests that ambulatory electroencephalogram (AEEG) and video electroencephalogram (VEEG) are also useful in the diagnosis in young children, in patients with poorly characterized seizure types, and in those with suspected psychogenic seizures, especially if episodes are frequent.

Ambulatory Electroencephalogram (AEEG) Monitoring
AEEG is beneficial in documenting seizures when routine EEG is non-diagnostic. In 2012 Faulkner et al. completed a study due to the International League Against Epilepsy (ILAE) guidelines recommend the use of prolonged EEG where the diagnosis of epilepsy or the classification of the seizure syndrome is proving difficult.¹⁰ Due to its limited provision, VEEG monitoring is unavailable to many patients. This study examined the utility of the alternate of outpatient AEEG. This retrospective study analyzed 324 consecutive prolonged outpatient AEEGs lasting 72 – 96 hours, without medication withdrawal. EEG data and the clinical records of 324 studies were examined. Two hundred nineteen (68%) studies gave positive data, 116 (36%) showed interictal epileptiform discharges (IEDs), 167 (52%) had events. One hundred five (32%) studies were normal. Overall 51% of studies changed management of which 22% of studies changed the diagnosis and 29% of studies refined the diagnosis by classifying the epilepsy into focal or generalized. In conclusion, this study confirmed the diagnostic utility of outpatient AEEG in the diagnosis of paroxysmal events. Therefore, when compared to routine EEG, AEEG demonstrated a higher yield and diagnostic sensitivity.

In 2012, Dash et al. evaluated AEEG and the cost effectiveness as an alternative to inpatient VEEG in adult patients.¹¹ This study evaluated EEG activity when patients are at home, without the necessity of admission to the hospital for prolonged VEEG monitoring. This was a prospective, cohort study performed in a Canadian academic center to assess the yield and tolerability of AEEG in the adult population. Over a period of 3 years, 101 patients were included (45 males, 56 females). Most of the patients had at least 1 previous routine EEG (93%). The primary reasons for the AEEGs were subdivided into 4 categories:

• To differentiate between seizures and non-epileptic events.
• To determine the frequency of seizures and epileptiform discharges.
• To characterize seizure type or localization.
• To potentially diagnose epilepsy.

The mean duration of AEEG recording was 15 – 96 hours. For 73 (72%) patients, the AEEG provided information that was useful for patient management. For 28 (28%) patients, the AEEG did not provide information on diagnosis because no events or epileptiform activity occurred. In only 1 patient was the AEEG inconclusive due to non-physiological artifacts. Three patients were referred for epilepsy surgery without the necessity of VEEG. The main use of AEEG is the characterization of patients with non-epileptic events and in patients with a diagnosis of epilepsy that is not clear. Quantification of spikes and seizures continue to improve the medical management of these patients. AEEG is a cost-effective solution for increasing demands for in-hospital VEEG monitoring of adult patients.

In 2013, Sanchez et al. evaluated survey data that indicated that continuous EEG (CEEG) monitoring is used with increased frequency to identify electrographic seizures in critically ill children.¹² Eleven North American centers retrospectively enrolled 550 critically ill children who underwent CEEG. Indications were encephalopathy with possible seizures in 67% of subjects, event characterization in 38% of subjects, and management of refractory status epilepticus in 11% of subjects. CEEG was initiated outside routine work hours in 47% of subjects. CEEG duration was < 12 hours in 16%, 12 – 24 hours in 34%, and > 24 hours in 48%. Substantial variability existed among sites in CEEG indications and neurologic diagnoses, yet within each acute neurologic diagnosis category a similar proportion of subjects at each site had electrographic seizures. Electrographic seizure characteristics including distribution and duration varied across sites and neurologic diagnoses. This indicated variability in practice. The results suggest that multicenter studies are feasible if CEEG monitoring pathways can be standardized. However, the data also indicated that electrographic seizure variability must be considered when designing studies that address the impact of electrographic seizures.

In 2015, Lawley et al.¹³ performed a systematic review on the use of AEEG in the diagnosis of epilepsy and nonepileptic attacks in adult patients. The findings confirmed that AEEG is a useful diagnostic tool in patients with equivocal findings on routine EEG studies and it influenced management decisions in the majority of studies. In addition, they noted that 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; therefore, additional research is warranted in this situation.

In 2016, Keezer and colleagues¹⁴ examined a consecutive sample of 72 individuals who had undergone 32-channel AEEG immediately following a routine EEG. Each recording was prospectively assessed for epileptiform discharges and non-epileptiform abnormalities. The median duration was 22.5 hours (interquartile range: 22.0 – 23.0). The sensitivity of AEEG was 2.23 times greater than that of routine EEG [sensitivity ratio: 2.23 (95% CI = 1.49 – 3.34)]. These findings support the use of AEEG in the diagnosis and characterization of epilepsy.

In 2020, UpTodate offered the following recommendations for the use of AEEG in the diagnosis of seizures and epilepsy:¹⁵

• Because of its longer duration of recording that typically includes one or more periods of sleep, AEEG monitoring can increase the yield of routine EEG in detecting IEDs.
• AEEG is most helpful in quantifying or capturing clinical events and associating these with the presence or absence of electrographic seizures. However, absence of an EEG correlate does not exclude epilepsy and AEEG cannot "rule out" epileptic seizures.

AEEG Utilization in Neonates

In 2010, Van Rooij et al. studied the effect of treatment of subclinical neonatal seizures detected with amplitude-integrated EEG.¹⁶ This was a randomized, multicenter controlled trial of 33 infants. The goal was to investigate how many subclinical seizures in full-term neonates with hypoxic-ischemic encephalopathy (HIE) would be missed without continuous EEG and whether immediate treatment of both clinical and subclinical seizures would result in a reduction in the total duration of seizures and a decrease in brain injury, as seen on magnetic resonance imaging (MRI) scans. Term infants with moderate to severe HIE and subclinical seizures were assigned randomly to either treatment of both clinical seizures and subclinical seizure patterns (group A) or blinding of the amplitude-integrated EEG registration and treatment of clinical seizures only (group B). All recordings were reviewed with respect to the duration of seizure patterns and the use of antiepileptic drugs (AEDs). MRI scans were scored for the severity of brain injury. Nineteen infants in group A and 14 infants in group B were available for comparison. The median duration of seizure patterns in group A was 196 minutes, compared with 503 minutes in group B (not statistically significant). No significant differences in the number of AEDs were seen. Five infants in group B received AEDs when no seizure discharges were seen on amplitude-integrated EEG traces. Six of 19 infants in group A and 7 of 14 infants in group B died during the neonatal period. A significant correlation between the duration of seizure patterns and the severity of brain injury in the blinded group, as well as in the whole group, was found. In this small group of infants with neonatal HIE and seizures, there was a trend for a reduction in seizure duration when clinical and subclinical seizures were treated. The severity of brain injury seen on MRI scans was associated with a longer duration of seizure patterns.

Video Electroencephalogram (VEEG) Monitoring
VEEG monitoring has generally been considered the standard to accurately differentiate epileptic from nonepileptic events and to localize the epileptogenic zone in patients being investigated for epilepsy surgery. VEEG is considered a necessary tool in determining surgical candidacy as it provides a detailed description of both ictal clinical signs and EEG discharge, as well as prolonged interictal recordings. Additionally, VEEG allows for the patient to be subjected to provocative measures such as medication reduction, sleep deprivation, hyperventilation, or photic stimulation to increase the likelihood of capturing epileptiform activity.^17,18,19

Occasionally, AEDs may be withdrawn in order to evaluate seizures. Several studies have shown that the rapid reduction of antiseizure drugs during video-EEG monitoring increases the risk of focal seizures and evolution to bilateral convulsive seizures.^20,21 Up to half of all patients who have never had a generalized seizure at baseline will have one in the context of rapid medication withdrawal.²⁰

In 2018, Kumar et al.²² evaluated the efficacy of rapid and slow AED taper in an open-label RCT. Patients aged 2 – 80 years with drug-resistant epilepsy (DRE) were randomly assigned (1:1) to rapid and slow AED taper groups. Outcome assessor was blinded to the allocation arms. Daily AED dose reduction was 30% to 50% and 15% to < 30% in the rapid and slow taper groups, respectively. The primary outcome was difference in mean duration of long-term VEEG monitoring between the rapid and slow AED taper groups. Secondary outcomes included diagnostic yield, secondary generalized tonic-clonic seizure (GTCS), 4- and 24-hour seizure clusters, status epilepticus, and need for midazolam rescue treatment. One hundred forty patients were randomly assigned to rapid (n = 70) or slow taper groups (n = 70), between June 13, 2016 and Feb. 20, 2017. The difference in mean long-term VEEG monitoring duration between the rapid and slow taper groups was -1.8 days (95% CI] -2.9 to -0.8, P = .0006). Of the secondary outcome measures, time to first seizure (2.9 ± 1.7 and 4.6 ± 3.0 days in the rapid and slow taper groups respectively, P = .0002) and occurrence of 4-hour seizure clusters (11.9% and 2.9% in the rapid and slow taper groups, respectively, P = .04) were statistically significant. None of the other safety variables were different between the 2 groups. Long-term VEEG monitoring diagnostic yield was 95.7% and 97.1%, in rapid and slow taper groups respectively (P = .46). The RCT concluded that rapid AED tapering has the advantage of significantly reducing long-term VEEG monitoring duration over slow tapering, without any serious adverse events.

In 2020, UpTodate offered the following recommendations for the use of VEEG in the diagnosis of seizures and epilepsy:¹⁵

• While relatively inexpensive and convenient to perform, the absence of simultaneous high-fidelity video recording, lack of ability to interact and test the patient during a spell, and a higher potential for artifact and misinterpretation are significant disadvantages of AEEG monitoring compared with inpatient VEEG recording.
• Inpatient VEEG monitoring combines both a video and EEG recording of clinical events, allows ongoing maintenance of video and EEG quality, permits interaction with the patient during or after an event, and allows medication withdrawal in a safer, monitored setting.
• VEEG is used most commonly to determine whether epilepsy is the cause of recurrent seizure-like events.
• VEEG can also aid in seizure classification, quantification, and determination of patient awareness of their seizures. It is also vital for presurgical evaluation of epilepsy patients.

VEEG Utilization in Neonates

In February 2013, the Vermont Oxford Network Collaborative attempted to create and implement an evidence-based standard-of-care approach to neonatal encephalopathy, to deliver consistent care, and to optimize outcomes.²³ By using an evidence-based approach, potentially better practices were developed by the topic expert, modified by the collaborative, and implemented at each hospital. These included the following:

• Timely identification of at-risk infants.
• Coordination with referring hospitals to ensure therapeutic hypothermia (TH) was available within 6 hours after birth.
• Staff education for both local and referring hospitals.
• Non-sedated MRI.
• Incorporating amplitude-integrated EEG into a TH protocol.
• Ensuring standard neurodevelopmental follow-up of infants.

Each center used these practices to develop a matrix for implementation. Local self-assessments directed the implementation and adaptation of the Potentially Better Practices at each center. Resources, based on common identified barriers, were developed and shared among the group. The implementation of a TH program to improve the consistency of care for patients in neonatal intensive care units (NICUs) is feasible using standard quality improvement methodology. The successful introduction of new interventions such as TH to the NICU culture requires a collaborative multidisciplinary team, use of a systematic quality improvement process and perseverance.

In April 2014, Glass et al. conducted a three-center observational cohort study to assess to assess the risk factors for electrographic seizures among neonates treated with TH for HIE.²⁴ Ninety term-neonates treated with hypothermia, were monitored with continuous VEEG within the first day of life (median age at onset of recording 9.5 hours, interquartile range 6.3 – 14.5), and continued for > 24 hours (total recording 93.3 hours, interquartile range 80.1 – 112.8 among survivors). A pediatric electroencephalographer at each site reviewed continuous VEEGs for electrographic seizures and initial EEG background category. A total of 43 (48%) had electrographic seizures, including 9 (10%) with electrographic status epilepticus. Abnormal initial EEG background classification (excessively discontinuous, depressed and undifferentiated, burst suppression, or extremely low voltage), but not clinical variables (including pH < 6.8, base excess ≤ -20, or 10-minute Apgar ≤ 3), was strongly associated with seizures. The authors concluded that electrographic seizures are common among neonates with HIE undergoing hypothermia and are difficult to predict based on clinical features. These results justify the recommendation for continuous VEEG monitoring in neonates treated with hypothermia.

Duration of VEEG Monitoring

In 2016, Hupalo et al.²⁵ sought to determine the optimal duration of the long-term VEEG and diagnostic utility of long term monitoring (LTM) in patients with epilepsy and other paroxysmal events in terms of diagnosis and management. These researchers carried out a retrospective analysis of 282 LTMs performed in the last 5 years in their Epilepsy Monitoring Unit (EMU), in 202 consecutive patients. The analysis included demographic data, monitoring time, number and type of paroxysmal events, the time until their onset, and the influence of LTM on the diagnosis and future management. There were 117 women and 85 men, mean age of 34.2 years. Mean duration of LTM was 5 days (range of 3 to 9), with 447 paroxysmal events recorded in 131 (65%) patients. Epileptic seizures were recorded in 82% cases (in 11% associated with psychogenic non-epileptic seizures [PNES]). The remaining 18% had either PNES (11%) or parasomnias (7%). Only 15% of epileptic seizures took place within the first 24 hours of the LTM (53% and 32% on the 2nd and 3rd day, respectively), whereas as many as 62% of PNES did (while only 28% and 10% on the second and third day, respectively). The LTM results changed the diagnosis in 36% of the patients, most frequently in PNES (from 2% to 14%). Overall, it changed the management in 64% of the patients, especially with PNES and those who underwent epilepsy surgery. The authors concluded that LTM should last at least 72 hours in patients with refractory epilepsy; most of cases with PNES could be diagnosed after 48 hours.

Digital Analysis of Electroencephalogram (DEEG)
DEEG is proposed as an automated analysis, by combining digital signals processing with neural network techniques. In 2013, Sharanreddy and Kulkami reported on automated EEG signal analysis for the identification of epilepsy seizures and brain tumors.²⁶ The system reviewed uses a multi-wavelet transform for feature extraction in which an input EEG signal is decomposed in a sub-signal. Irregularities and unpredictable fluctuations present in the decomposed signal are measured using approximate entropy. A feed-forward neural network is used to classify the EEG signal as a normal, epilepsy or brain tumor signal. The proposed technique is implemented and tested on data of 500 EEG signals for each disease. Results are promising, with classification accuracy of 98% for normal, 93% for epilepsy and 87% for brain tumor. Along with classification, the paper also highlights the EEG abnormalities associated with brain tumor and epilepsy seizure.

Summary of Evidence 
The evidence for the use of ambulatory electroencephalogram (AEEG) monitoring in individuals includes one randomized controlled, prospective, and clinical trial. Relevant outcomes are overall survival, morbid events, functional outcomes, and treatment-related mortality and morbidity. AEEG monitoring is not necessary to evaluate most seizures, as they are usually readily diagnosed by routine or resting electroencephalogram (EEG) studies and patient history. However, AEEGs are helpful at identifying seizures that are unrecognized or unreported by the individual and are easily accomplished on an outpatient basis. Therefore, the evidence is sufficient that this technology results in a meaningful improvement for the net health outcome in the treatment of adults, children, and neonates. 

The evidence for the use of video electroencephalogram (VEEG) monitoring in individuals includes one cohort study, and professional guidelines/recommendations. Relevant outcomes are overall survival, morbid events, functional outcomes, and treatment-related mortality and morbidity. VEEG is a useful tool to diagnosis seizure type and epilepsy syndrome in individuals who present diagnostic difficulties following clinical assessment and standard EEG; for identification and localization of a seizure focus in individuals with intractable epilepsy who are being considered for surgery; to monitor neonates with hypoxic-ischemic encephalopathy (HIE) who are being treated with therapeutic hypothermia (TH); and to document provocation of seizures after medication withdrawal for the purpose of making medication adjustments or otherwise determining an appropriate treatment plan. The evidence is sufficient that this technology results in a meaningful improvement for the net health outcome in the treatment of adults, children, and neonates. 

The evidence for the use of digital EEG (DEEG) analysis of EEG signal monitoring in individuals includes reports and reviews, no known clinical trials. Relevant outcomes are overall survival, morbid events, functional outcomes, and treatment-related mortality and morbidity. Overall, there is a lack of evidence that clinical outcomes are improved. The evidence is insufficient to determine the effects of the technology on health outcomes. Digital analysis of electroencephalogram (DEEG) is considered not medically necessary as there is no evidence that such additional processing and interpretation has been shown to improve outcomes in individual management.

Practice Guidelines and Position Statements
American Clinical Neurophysiology Society (ACNS)

According to ACNS, guidelines for long term EEG monitoring (2008) (e.g., ambulatory EEG) include the following:⁷

• Identification of epileptic paroxysmal electrographic and/or behavioral abnormalities. These included epileptic seizures, overt and subclinical, and documentation of interictal epileptiform discharges.
• Verification of the epileptic nature of the new “spells” in a patient with previously documented and controlled seizures.
• Classification of clinical seizure type(s) in a patient with documented but poorly characterized epilepsy.

The ACNS further stated that EEG and/or behavioral abnormalities may assist in the differential diagnosis between epileptic disorders and conditions associated with intermittent symptoms due to non-epileptic mechanisms (e.g., syncope, narcolepsy, other sleep disturbances, psychogenic seizures).⁷

The 2011 ACNS’s Guidelines on “Continuous EEG Monitoring in Neonates” includes the following:²⁷

• “The use of synchronized video monitoring: Synchronized video is strongly recommended for the characterization of events and is often helpful in assessing for artifacts that may mimic electrographic seizures … ”
• “The committee recommends that neonates at high risk for seizures be monitored with conventional EEG for 24 hours to screen for seizures. Seizures suspected by aEEG were documented in more than half of term neonates with hypoxic-ischemic encephalopathy who fulfilled the criteria for selective head cooling within 6 hours of birth…and studies of neonates undergoing EEG monitoring during therapeutic hypothermia for hypoxic-ischemic encephalography have also demonstrated a high incidence of seizures … ”
• “If seizures are detected, it is recommended that EEG monitoring continue until the patient has been found to be seizure-free for at least 24 hours, unless in consultation with a neurologist a decision is made to discontinue monitoring earlier … ”

American Academy of Pediatrics (AAP)

The AAP Clinical Report on Hypothermia and Neonatal Encephalopathy published in 2014 concluded:²⁸

• “Medical centers offering hypothermia should be capable of providing comprehensive clinical care, including … seizure detection and monitoring with aEEG or EEG … ”
• “If preferential head cooling is used, an abnormal background activity on either EEG or aEEG also is required … ”

American Academy of Neurology (AAN)

The July 1997 Assessment of Digital EEG, Quantitative EEG, and EEG Brain Mapping report by the American Academy of Neurology and the American Clinical Neurophysiology Society²⁹ provided the following recommendations:

A. “Digital EEG is an established substitute for recording, reviewing and storing a paper EEG record. It is a clear technical advance over previous paper methods. It is highly recommended. (Class III evidence, Type C recommendation)

B. EEG brain mapping and other advanced QEEG techniques should be used only by physicians highly skilled in clinical EEG, and only as an adjunct to and in conjunction with traditional EEG interpretation. These tests may be clinically useful only for patients who have been well selected on the basis of their clinical presentation.

C. Certain quantitative EEG techniques are considered established as an addition to digital EEG in:

• C.1 Epilepsy: For screening for possible epileptic spikes or seizures in long-term EEG monitoring or ambulatory recording to facilitate subsequent expert visual EEG interpretation. (Class I and II evidence, Type A recommendation as a practice guideline)
• C.2 OR and ICU monitoring: For continuous EEG monitoring by frequency-trending to detect early, acute intracranial complications in the OR or ICU, and for screening for possible epileptic seizures in high-risk ICU patients. (Class II evidence, Type B recommendation as a practice option)

D. Certain quantitative EEG techniques are considered possibly useful practice options as an addition to digital EEG in:

• D.1 Epilepsy: For topographic voltage and dipole analysis in presurgical evaluations. (Class II evidence, Type B recommendation)
• D.2 Cerebrovascular Disease: Based on Class II and III evidence, QEEG in expert hands may possibly be useful in evaluating certain patients with symptoms of cerebrovascular disease whose neuroimaging and routine EEG studies are not conclusive. (Type B recommendation)
• D.3 Dementia: Routine EEG has long been an established test used in evaluations of dementia and encephalopathy when the diagnosis remains unresolved after initial clinical evaluation. In occasional clinical evaluations, QEEG frequency analysis may be a useful adjunct to interpretation of the routine EEG when used in expert hands. (Class II and III evidence as a possibly useful test, Type B recommendation)

E. On the basis of current clinical literature, opinions of most experts, and proposed rationales for their use, QEEG remains investigational for clinical use in post-concussion syndrome, mild or moderate head injury, learning disability, attention disorders, schizophrenia, depression, alcoholism, and drug abuse. (Class II and III evidence, Type D recommendation)

F. On the basis of clinical and scientific evidence, opinions of most experts, and the technical and methodologic shortcomings, QEEG is not recommended for use in civil or criminal judicial proceedings. (Strong Class III evidence, Type E recommendation)

G. Because of the very substantial risk of erroneous interpretations, it is unacceptable for any EEG brain mapping or other QEEG techniques to be used clinically by those who are not physicians highly skilled in clinical EEG interpretation. (Strong Class III evidence, Type E recommendation)”

The AAN et al., included their ratings for strength and quality of the evidence used for their recommendations:

“Strength of Recommendation Ratings:

• Type A — Strong positive recommendation, based on Class I evidence, or overwhelming Class II evidence.
• Type B — Positive recommendation, based on Class II evidence.
• Type C — Positive recommendation, based on strong consensus of Class III evidence.
• Type D — Negative recommendation, based on inconclusive or conflicting Class II evidence.
• Type E — Negative recommendation, based on evidence of ineffectiveness or lack of efficacy.

Quality of evidence ratings

• Class I — Evidence provided by one or more well-designed, prospective, blinded, controlled clinical studies.
• Class II — Evidence provided by one or more well-designed clinical studies such as case control, cohort studies, etc.
• Class III — Evidence provided by expert opinion, nonrandomized historical controls or case reports of one or more.”

National Institute for Health and Care Excellence (NICE)

In 2012, the United Kingdom’s NICE published their clinical guideline for diagnosis and management of epilepsy.³⁰ This guidance was reaffirmed Feb. 11, 2020. Investigation after a seizure episode, particularly the first seizure, EEGs should follow these recommendation steps:

• “Children, young people and adults requiring an EEG should have the test performed soon after it has been requested.
• An EEG should be performed only to support a diagnosis of epilepsy in adults in whom the clinical history suggests that the seizure is likely to be epileptic in origin.
• An EEG should be performed only to support a diagnosis of epilepsy in children and young people. If an EEG is considered necessary, it should be performed after the second epileptic seizure but may, in certain circumstances, as evaluated by the specialist, be considered after a first epileptic seizure.
• An EEG should not be performed in the case of probable syncope because of the possibility of a false-positive result.
• The EEG should not be used to exclude a diagnosis of epilepsy in a child, young person or adult in whom the clinical presentation supports a diagnosis of a nonepileptic event.
• The EEG should not be used in isolation to make a diagnosis of epilepsy.
• An EEG may be used to help determine seizure type and epilepsy syndrome in children, young people and adults in whom epilepsy is suspected. This enables them to be given the correct prognosis.
• In children, young people and adults presenting with a first unprovoked seizure, unequivocal epileptiform activity shown on EEG can be used to assess the risk of seizure recurrence.
• For children, young people and adults in whom epilepsy is suspected, but who present diagnostic difficulties, specialist investigations should be available.
• Repeated standard EEGs may be helpful when the diagnosis of the epilepsy or the syndrome is unclear. However, if the diagnosis has been established, repeat EEGs are not likely to be helpful.
• Repeated standard EEGs should not be used in preference to sleep or sleep-deprived EEGs.
• When a standard EEG has not contributed to diagnosis or classification, a sleep EEG should be performed.
• In children and young people, a sleep EEG is best achieved through sleep deprivation or the use of melatonin.
• Long-term video or ambulatory EEG may be used in the assessment of children, young people and adults who present diagnostic difficulties after clinical assessment and standard EEG.
• Provocation by suggestion may be used in the evaluation of non-epileptic attack disorder. However, it has a limited role and may lead to false-positive results in some people.
• Photic stimulation and hyperventilation should remain part of standard EEG assessment. The child, young person or adult and family and/or carer should be made aware that such activation procedures may induce a seizure and they have a right to refuse.”

Ongoing and Unpublished Clinical Trials
Some currently unpublished trials that might influence this policy are listed in Table 1.

Table 1. Summary of Key Trials 

NCT: National Clinical Trial.

References 

1. Epilepsy Society. Electroencephalogram (EEG). November 2019. Available at <https://www.epilepsysociety.org.uk> (accessed June 30, 2020).
2. Epilepsy – Assessment of seizures. Epilepsy Foundation. April 1, 2004. Available at: <https://www.epilepsy.com> (accessed July 1, 2020).
3. Electroencephalography. Available at <https://www.caam.rice.edu> (accessed June 30, 2020).
4. NIH – Neurological diagnostic tests and procedures fact sheet. National Institute of Neurological Disorders and Stroke. April 10, 2019. Available at <http://www.ninds.nih.gov> (accessed June 26, 2020).
5. Waterhouse E. Ambulatory EEG. Medscape. November 12, 2019. Available at <https://emedicine.medscape.com> (accessed July 1, 2020).
6. Centers for Medicare & Medicaid Services (CMS). National Coverage Determination (NCD) for Ambulatory EEG Monitoring (160.22). Baltimore, MD: CMS. June 12, 1984. Available at <http://www.cms.hhs.gov> (accessed July 1, 2020).
7. American Clinical Neurophysiology Society. Guideline twelve: Guidelines for long term monitoring for epilepsy. J Clin Neurophysiol. June 2008. Available at <https://www.researchgate.net> (accessed June 29, 2020).
8. Moeller J, Haider H, Hirsch L. Video and ambulatory EEG monitoring in the diagnosis of seizures and epilepsy. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. Available at <http://www.uptodate.com> (accessed 2020 July 1).
9. FDA – CDRH Clarifies Classification of EEG Devices. December 13, 2011, revised December 14, 2017. U.S. Food and Drug Administration, Center for Devices and Radiologic Health. Available at <http://www.fda.gov> (accessed on June 26, 2020).
10. Faulkner H, Arima H, Mohamed A. The utility of prolonged outpatient ambulatory EEG. Seizure. September 2012; 21(7):491-495. PMID 22658455
11. Dash D, Hernandez-Ronquillo L, Moien-Afshari F, et al. Ambulatory EEG: a cost-effective alternative to inpatient video-EEG in adult patients. Epileptic Disord. September 2012; 14(3):290-297. PMID 22963900
12. Sánchez SM., Arndt DH, Carpenter JL, et al. Electroencephalography monitoring in critically ill children: current practice and implications for future study design. Epilepsia. August 2013; 54(8):1419-1427. PMID 23848569
13. Lawley A, Evans S, Manfredonia F, et al. The role of outpatient ambulatory electroencephalography in the diagnosis and management of adults with epilepsy or nonepileptic attack disorder: A Systematic Literature Review. December 2015; 53:26-30. PMID 26515156
14. Keezer M, Simard-Tremblay E, Veilleux M. The Diagnostic Accuracy of Prolonged Ambulatory Versus Routine EEG. Clin EEG Neurosci. April 2016; 47(2):157-161. PMID 26376916
15. Moeller J, Haider H, Hirsch L. Video and ambulatory EEG monitoring in the diagnosis of seizures and epilepsy. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. Available at <http://www.uptodate.com> (accessed 2020 June 30).
16. van Rooij L, Toet M, van Huffelen A, et al. Effect of treatment of subclinical neonatal seizures detected with aEEG: randomized, controlled trial. Pediatrics. February 2010; 125(2):e358-66. PMID 20100767
17. Xiang X., Fang J, Guo Y, Eet al. Differential diagnosis between epileptic seizures and psychogenic nonepileptic seizures based on semiology. Acta Epileptologica. October 21, 2019; Available at <https://aepi.biomedcentral.com> (accessed July 2, 2020).
18. Wirrell E, Kozlik S, Tellez J, et al. Ambulatory electroencephalography (EEG) in children: diagnostic yield and tolerability. J Child Neurol. June 2008; 23(6):655-662. PMID 18539990
19. Mansouri A, Fallah A, Valiante TA. Determining surgical candidacy in temporal lobe epilepsy. Epilepsy Res Treat. 2012:706-917. PMID 22957238
20. Marciani M, Gotman J, Andermann F, et al. Patterns of seizure activation after withdrawal of antiepileptic medication. Neurology. 1985; 35 (11):1537-1543. PMID 4058743
21. Marks DA, Katz A, Scheyer R, et al. Clinical and electrographic effects of acute anticonvulsant withdrawal in epileptic patients. Neurology. April 1991; 41(4):508-512. PMID 2011247
22. Kumar S, Ramanujam B, Chandra PS, et al. Randomized controlled study comparing the efficacy of rapid and slow withdrawal of antiepileptic drugs during long-term video-EEG monitoring. Epilepsia. Feb 2018; 59(2):460-467. PMID 29218705
23. Olsen SL, Dejonge M, Kline A, et al. Optimizing therapeutic hypothermia for neonatal encephalopathy. Pediatrics. February 2013; 131(2): e591-603. PMID 23296428
24. Glass HC1, Wusthoff CJ, Shellhaas RA, et al. Risk factors for EEG seizures in neonates treated with hypothermia: a multicenter cohort study. Neurology. April 8 20148; 82(14):1239-1244. PMID 24610326
25. Hupalo M, Smigielski JW, Jaskolski DJ. Optimal time of duration of a long-term video-EEG monitoring in paroxysmal events - A retrospective analysis of 282 sessions in 202 patients. Neurol Neurochir Pol. 2016; 50(5):331-335. PMID 27591057
26. Sharanreddy M, Kulkarni PK. Automated EEG signal analysis for identification of epilepsy seizures and brain tumor. J Med Eng Technol. November 2013; 37(8):511-519. PMID 24116656
27. Shellhaas RA, Chang T, Tsuchida T, et al. The American Clinical Neurophysiology Society's Guideline on Continuous Electroencephalography Monitoring in Neonates. J Clin Neurophysiol. December 2011; 28(6):611-617. PMID 22146359
28. Papile L, Baley J, Benitz W, et al. Committee on Fetus and Newborn, Hypothermia and neonatal encephalopathy. Pediatrics. June 2014; 133(6):1146-1150. PMID 24864176
29. Nuwer, M. Assessment of digital EEG, quantitative EEG, and EEG brain mapping: report of the American Academy of Neurology and the American Clinical Neurophysiology Society. Neurology. July 1997; 49(1):277-292. PMID 9222209
30. NICE – Epilepsies: diagnosis and management. (Clinical guideline [CG137] [January 12, 2012; updated February 11, 2020]). National Institute for Health and Clinical Excellence. Available at <http://www.nice.org.uk> (accessed June 25, 2020).
31. Electroencephalograms (EEGs) (Archived). Chicago, Illinois: Blue Cross Blue Shield Association Medical Policy Reference Manual (2009 September) Medicine: 2.01.14. 

Coding Section 

Procedure and diagnosis codes on Medical Policy documents are included only as a general reference tool for each policy. They may not be all-inclusive. 

This medical policy was developed through consideration of peer-reviewed medical literature generally recognized by the relevant medical community, U.S. FDA approval status, nationally accepted standards of medical practice and accepted standards of medical practice in this community, Blue Cross Blue Shield Association technology assessment program (TEC) and other nonaffiliated technology evaluation centers, reference to federal regulations, other plan medical policies, and accredited national guidelines.

"Current Procedural Terminology © American Medical Association. All Rights Reserved" 

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