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Clinical Policy Bulletin:
Ambulatory Electroencephalography
Number: 0425


Aetna considers ambulatory electroencephalography (EEG) medically necessary for any of the following conditions:

  1. Classification of seizure type in members who have epilepsy (routine EEG is equivocal) -- only ictal recordings can reliably be used to classify seizure type (or types) which is important in selecting appropriate anti-epileptic drug therapy; or

  2. Diagnosis of a seizure disorder (epilepsy) -- members who have episodes suggestive of epilepsy when history, examination, and routine EEG do not resolve the diagnostic uncertainties (routine EEG should be negative with provocative measures); or

  3. Localization of the epileptogenic region of the brain during pre-surgical evaluation -- to identify appropriate surgical candidates.

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.

See also CPB 0221 - Quantitative EEG (Brain Mapping), CPB 0289 - Grid Monitoring and Intraoperative Electroencephalography, and CPB 0322 - Electroencephalographic (EEG) Video Monitoring.


A 24-hour ambulatory electroencephalogram (EEG) 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.

The advantage of 24-hour ambulatory EEG 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 ambulatory EEG monitors.  Lighter weight, smaller, and faster processors with larger digital storage capacity have overcome earlier limitations on EEG recording and analysis.  Commercially available ambulatory EEG 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.

CPT Codes / HCPCS Codes / ICD-9 Codes
CPT codes covered if selection criteria are met:
ICD-9 codes covered if selection criteria are met:
345.00 - 345.91 Epilepsy and recurrent seizures
779.0 Convulsions in newborn
780.32 Complex febrile convulsions
780.33 Post traumatic seizures
780.39 Other convulsions
781.0 Abnormal involuntary movements

The above policy is based on the following references:
  1. Kaplan PW, Schachter SC. The role of the neurologist in the management of epilepsy: Guidelines and tools for patient care. The Neurologist. 1996;2:302-314.
  2. Lagerlund TD, Cascino GD, Cicora KM, Sharbrough FW. Long-term electroencephalographic monitoring for diagnosis and management of seizures. Mayo Clin Proc. 1996;71(10):1000-1006.
  3. Smith MC, Buelow JM. Epilepsy. Disease-A-Month. 1996;42(11):729-827.
  4. American Medical Association. 24-hour ambulatory EEG monitoring. Diagnostic and Therapeutic Technology Assessment (DATTA). JAMA. 1983;250(24):3340.
  5. Burgess RC. Ambulatory cassette EEG systems. Technology and equipment review. J Clin Neurophysiol. 1991;8(3):351-359.
  6. Gilliam F, Kuzniecky R, Faught E. Ambulatory EEG monitoring. J Clin Neurophysiol. 1999;16(2):111-115.
  7. Morris GL. The clinical utility of computer-assisted ambulatory 16 channel EEG. J Med Engineering Technol. 1997;21(2):47-52.
  8. Schomer DL, Ives JR, Schachter SC. The role of ambulatory EEG in the evaluation of patients for epilepsy surgery. J Clin Neurophysiol. 1999;16(2):116-129.
  9. Olson DM. Success of ambulatory EEG in children. J Clin Neurophysiol. 2001;18(2):158-161.
  10. Worrell GA, Lagerlund TD, Buchhalter JR. Role and limitations of routine and ambulatory scalp electroencephalography in diagnosing and managing seizures. Mayo Clin Proc. 2002;77(9):991-998.
  11. Chang BS, Ives JR, Schomer DL, Drislane FW. Outpatient EEG monitoring in the presurgical evaluation of patients with refractory temporal lobe epilepsy. J Clin Neurophysiol. 2002;19(2):152-156.
  12. Waterhouse E. New horizons in ambulatory electroencephalography. IEEE Eng Med Biol Mag. 2003;22(3):74-80.
  13. Ross SD, Estok R,Chopra S, French J. Management of newly diagnosed patients with epilepsy: A systematic review of the literature. Evidence Report/Technology Assessment No. 39. Prepared by MetaWorks, Inc. for the Agency for Healthcare Reseach and Quality (AHRQ). AHRQ Publication No. 01-E038. Rockville, MD: AHRQ; September 2001.
  14. Scottish Intercollegiate Guidelines Network (SIGN). Diagnosis and management of epilepsy in adults. SIGN Publication No. 70. Edinburgh, Scotland: SIGN; updated October 2005. 
  15. Scottish Intercollegiate Guidelines Network (SIGN). Diagnosis and management of epilepsies in children and young people. SIGN Publication No. 81. Edinburgh, Scotland: SIGN; March 2005.
  16. Watemberg N, Tziperman B, Dabby R, et al. Adding video recording increases the diagnostic yield of routine electroencephalograms in children with frequent paroxysmal events. Epilepsia. 2005;46(5):716-719.
  17. National Collaborating Centre for Primary Care. The epilepsies. The diagnosis and management of the epilepsies in adults and children in primary and secondary care. Clinical Guideline 20. London, UK: National Institute for Clinical Excellence (NICE); October 2004. Available at: Accessed June 29, 2005.
  18. Wirrell E, Kozlik S, Tellez J, et al. Ambulatory electroencephalography (EEG) in children: Diagnostic yield and tolerability. J Child Neurol. 2008;23(6):655-662.
  19. Gonzalez de la Aleja J, Saiz Díaz RA, Martín García H, et al. The role of ambulatory electroencephalogram monitoring: Experience and results in 264 records. Neurologia. 2008;23(9):583-586.
  20. Brigo F. An evidence-based approach to proper diagnostic use of the electroencephalogram for suspected seizures. Epilepsy Behav. 2011;21(3):219-222.
  21. Dash D, Hernandez-Ronquillo L, Moien-Afshari F, Tellez-Zenteno JF. Ambulatory EEG: A cost-effective alternative to inpatient video-EEG in adult patients. Epileptic Disord. 2012;14(3):290-297.
  22. Seneviratne U, Mohamed A, Cook M, D'Souza W. The utility of ambulatory electroencephalography in routine clinical practice: A critical review. Epilepsy Res. 2013;105(1-2):1-12.

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Copyright Aetna Inc. All rights reserved. Clinical Policy Bulletins are developed by Aetna to assist in administering plan benefits and constitute neither offers of coverage nor medical advice. This Clinical Policy Bulletin contains only a partial, general description of plan or program benefits and does not constitute a contract. Aetna does not provide health care services and, therefore, cannot guarantee any results or outcomes. Participating providers are independent contractors in private practice and are neither employees nor agents of Aetna or its affiliates. Treating providers are solely responsible for medical advice and treatment of members. This Clinical Policy Bulletin may be updated and therefore is subject to change.
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