The American Clinical Neurophysiology Society guidelines provide a foundational framework for the optimal implementation of electroencephalography (EEG), spanning a range of critical areas, from electrode placement systems to assessing brain death and applications in neonatal EEG. The foundational Guideline 1 emphasizes the essential standards for EEG recordings, underscoring the significance of precise equipment, meticulous calibration, and vigilant monitoring methods (Sinha et al., 2016). Subsequent guidelines explore electrode placement, montage organization, professional qualifications, pediatric EEG considerations, brain death determination, standardized reporting, digital EEG recording, and neonatal EEG utilization. Each guideline contributes valuable insights to the continuously evolving domain of EEG to enhance the quality and consistency of EEG procedures.
Guideline 1:
Guideline 1 is the cornerstone in establishing the essential benchmarks for clinical electroencephalography (EEG) recordings. It underscores the paramount significance of employing suitable equipment and electrodes to ensure the precise acquisition of data (Sinha et al., 2016). A minimal requirement of sixteen channels is recommended to effectively capture the full spectrum of both normal and aberrant EEG patterns (Sinha et al., 2016). While adherence to electrical standards is imperative, shielding typically proves unnecessary. Encouraging the adoption of digital EEG equipment, this guideline highlights the inherent advantages, including heightened sensitivity and enhanced storage capabilities. Electrodes should be chosen for their low noise and minimal drift attributes, accompanied by rigorous disinfection protocols to uphold infection control standards. The renowned 10-20 System is advocated for electrode placement alongside a mandate to monitor interelectrode impedances. Integral aspects of EEG recordings, such as calibration with sensitivity set within the range of 5 to 10 μV/mm, judicious filter application, and essential procedures like photic stimulation, hyperventilation, and sleep recordings in cases of seizure disorders, are emphasized (Sinha et al., 2016). Vigilant monitoring of the patient’s level of consciousness and any clinical events is deemed crucial, with due caution exercised during special procedures. Video recording is commonly integrated, and the storage of EEG data should align with institutional policies, all collectively forming the foundational framework for ensuring high-quality EEG recordings in the clinical setting (Sinha et al., 2016).
Guideline 2
The guideline discusses the evolution of EEG electrode placement systems, focusing on the transition from the 10-20 system to the 10-10 system, which offers higher electrode density and improved spatial resolution (Acharya et al., 2016). The key modifications involve replacing inconsistent electrode designations like T3/T4 with T7/T8 and T5/T6 with P7/P8 for better consistency and clarity (Acharya et al., 2016). The guideline provides a detailed alphanumeric nomenclature, emphasizing the desirable characteristics for electrode naming, which should be based on underlying brain lobes and a coordinate system. While the 10-10 system enhances spatial accuracy, it highlights potential challenges, including increased time and cost for routine EEGs, equipment limitations, and the need for educational adjustments (Acharya et al., 2016). The authors recommend a balanced approach, suggesting the 10-10 system for patients requiring precise localization, with the flexibility to use a subset of electrodes based on clinical needs, reserving the full 10-10 system for advanced digital analysis (Acharya et al., 2016).
Guideline 3
Guideline 3 addresses the organization of montages in electroencephalography (EEG), emphasizing the importance of logical and standardized montage designs for clinical practice (Acharya et al., 2016). It acknowledges the vast number of possible montages but highlights the need for a basic set of recommended montages to enhance communication and consistency among EEG laboratories (Acharya et al., 2016). These montages are intended to be a minimum standard, with the flexibility for additional montages as required by specific recording circumstances (Acharya et al., 2016). The guidelines classify montages into three categories: longitudinal bipolar (LB), transverse bipolar (TB), and referential (R), based on the number of channels they utilize (Acharya et al., 2016). Furthermore, they recommend a “left above right” order, encourage the use of at least 16 channels, and suggest the inclusion of a single-channel electrocardiogram (ECG) to distinguish between EEG and ECG artifacts (Acharya et al., 2016). While the guidelines offer a framework for standardization, they acknowledge that modifications may be needed to accommodate variations in clinical practice (Acharya et al., 2016).
Guideline 4
Guideline 4 establishes standards for clinical electroencephalography (EEG) practice, focusing on the qualifications of professionals involved in EEG interpretation and the organization of EEG laboratories (ACNS, 2016). It requires clinical electroencephalographers to hold a medical degree with board eligibility or certification in neurology, pediatric neurology, neurosurgery, or psychiatry (ACNS, 2016). Electroneurodiagnostic technologists are expected to meet qualifications set by relevant organizations, with encouragement for certifications like R. EEG T. and R. EP T. provided by the American Board of Electroencephalographic and Evoked Potentials Technologists (ABRET) (ACNS, 2016). A key principle is that clinical interpretation of EEGs must be the responsibility of qualified electroencephalographers, not technologists, although the latter can provide descriptive technical reports (ACNS, 2016). The guideline emphasizes the need for orderly record-keeping, availability of records for review by referring physicians, and adherence to technical standards in EEG equipment selection as per prior guidelines, ensuring the integrity and quality of EEG procedures and reports in clinical settings (ACNS, 2016).
Guideline 5
Guideline 5 provides specific recommendations for clinical electroencephalography (EEG) recording in children, particularly neonates, infants, and young children, complementing the general guidelines outlined in Guideline 1, which primarily covers EEG recording in adults (Kuratani et al., 2016). It underscores the need for meticulous electrode application due to children’s propensity to move during recordings (Kuratani et al., 2016). The use of the full 21 electrodes in the International 10-20 system is recommended, and the standard montages for adults should be applied to children (Kuratani et al., 2016). Special considerations are given for managing active children, adjusting sensitivity for infants, and incorporating hyperventilation and photic stimulation for specific diagnostic purposes (Kuratani et al., 2016). Notably, neonatal EEG recordings are further subdivided, emphasizing polygraphic variables in addition to EEG, and gestational and postmenstrual ages are crucial for interpretation (Kuratani et al., 2016). Clear documentation of clinical states and continuous observation by technologists are highlighted, with further nuances discussed in the guideline for neonates, where additional monitoring of physiological variables is essential (Kuratani et al., 2016).
Guideline 6
Guideline 6 of the EEG recording standards for determining brain death emphasizes using a complete set of scalp electrodes and maintaining appropriate interelectrode impedances (Stecker et al., 2016). Electrodes should be placed over all major brain areas to ensure the comprehensive assessment of EEG activity, and single-channel or dual-channel recording devices are deemed inadequate for this purpose (Stecker et al., 2016). The guidelines stress the need for stable, low-impedance electrodes, as high impedances can distort EEG recordings and introduce noise. Furthermore, the integrity of the entire recording system must be tested, and montages for interpreting electrocerebral inactivity (ECI) should include electrode pairs at least 10 centimeters apart (Stecker et al., 2016). The sensitivity should be increased to a maximum of 2 mV/mm for at least 30 minutes, and appropriate filter settings should be applied to avoid the attenuation of low-voltage activity (Stecker et al., 2016). Additional monitoring techniques are encouraged to identify and address artifacts, and EEG reactivity to stimuli should not be present (Stecker et al., 2016). Only qualified EEG technologists should conduct these recordings, and repeat EEG assessments may be needed if ECI is in doubt (Stecker et al., 2016). Physiologic variables, medications, and clinical context must also be documented.
Guideline 7
Guideline 7 provides a standardized reporting format for adult routine scalp electroencephalography (rsEEG) to enhance clarity and consistency in communicating EEG results (Tatum et al., 2016). The purpose of this guideline is to minimize the variability in EEG reporting styles, especially given the increasing use of video technology in rsEEG (Tatum et al., 2016). The recommended format includes five sections: History, which provides patient identification and clinical context; Technical Description, detailing recording conditions and parameters; EEG Description, describing the background activity, waveforms, and abnormalities; Impression, summarizing the findings in clear, concise terms; and Clinical Correlation, which interprets the EEG results in the context of the patient’s condition (Tatum et al., 2016). The guideline ensures that EEG reports are readily interpretable by clinicians from various backgrounds, improving clinical care and research consistency (Tatum et al., 2016).
Guideline 8
Guideline 8 discusses the recording of clinical electroencephalography (EEG) onto digital media, offering several advantages, including space efficiency and the ability to review and process EEG records (Shellhaas et al., 2011). Patient information, calibration signals, and technologist comments should be electronically recorded alongside EEG signals, providing a comprehensive and adaptable recording (Shellhaas et al., 2011). Recommendations cover acquisition specifications, such as sampling rates and resolution, emphasizing the need for a dynamic range capable of resolving EEG down to 0.5 uV (Shellhaas et al., 2011). Various recording media, including magnetic and optical storage, are deemed suitable, although potential issues with obsolescence and durability are noted. Manufacturers are urged to use widely supported storage media and nonproprietary data formats to ensure long-term data access (Shellhaas et al., 2011). The guideline also addresses the display of recorded EEG data, calling for screen and paper displays to match traditional paper recordings in resolution while offering flexibility in scaling and montage options (Shellhaas et al., 2011). Additionally, the ability to compare different EEG segments is highlighted, making it an important reference for clinical EEG recording on digital media.
Guideline 9
The ninth guideline by the American Clinical Neurophysiology Society discusses using various EEG monitoring techniques in neonates for seizure detection and assessment of the background (ACNS, 2016). It highlights that conventional EEG remains the gold standard for precise seizure diagnosis. While amplitude-integrated EEG (aEEG) can be a complementary tool in cases where conventional EEG is not readily available, its sensitivity for seizure detection is limited, especially when using single-channel aEEG (ACNS, 2016). The document stresses the importance of prompt confirmation and refinement of electrodiagnosis through conventional EEG when seizures are suspected on aEEG. Additionally, it mentions other EEG monitoring modalities, like density spectral arrays and envelope trend displays, but notes that further research is needed before their widespread clinical adoption (ACNS, 2016). The consensus acknowledges the legal implications of these recommendations. It emphasizes that any form of EEG recording is better than none, even if its impact on long-term clinical outcomes remains uncertain (ACNS, 2016). The document discourages unnecessary transportation of neonates solely for EEG monitoring purposes.
Conclusion
These nine guidelines from the American Clinical Neurophysiology Society collectively form a comprehensive framework for electroencephalography, offering guidance on equipment, electrode placement, montage organization, professional qualifications, pediatric and neonatal EEG, brain death determination, standardized reporting, and digital recording. By addressing the intricate details of EEG, these guidelines contribute to the standardization and refinement of EEG practices, ultimately benefiting patients and healthcare providers. They emphasize the significance of precise data collection, interpretation, and continuous improvement in the ever-evolving field of neurophysiology.
References
Acharya, J. N., Hani, A. J., Cheek, J., Thirumala, P., & Tsuchida, T. N. (2016). American Clinical Neurophysiology Society Guideline 2: Guidelines for standard electrode position nomenclature. The Neurodiagnostic Journal, 56(4), 245-252. https://doi.org/10.1080/21646821.2016.1245558
Acharya, J. N., Hani, A. J., Thirumala, P., & Tsuchida, T. N. (2016). American Clinical Neurophysiology Society Guideline 3: A proposal for standard montages to be used in clinical EEG. The Neurodiagnostic Journal, 56(4), 253-260. https://doi.org/10.1080/21646821.2016.1245559
ACNS. (2016). Guideline 4: Standards of Practice in Clinical Electroencephalography. ACNS – American Clinical Neurophysiology Society. https://www.acns.org/pdf/guidelines/Guideline-4.pdf
ACNS. (2016). American Clinical Neurophysiology Society Guideline 8: Guidelines for Recording Clinical EEG on Digital Media. https://medi-guide.meditool.cn/ymtpdf/02507BE5-E7D7-723A-3B82-8C7BF038BFD5.pdf
Kuratani, J., Pearl, P. L., Sullivan, L. R., Riel-Romero, R. M., Cheek, J., Stecker, M. M., Orta, D. S., Selioutski, O., Sinha, S. R., Drislane, F. W., & Tsuchida, T. N. (2016). American Clinical Neurophysiology Society Guideline 5: Minimum technical standards for pediatric electroencephalography. The Neurodiagnostic Journal, 56(4), 266-275. https://doi.org/10.1080/21646821.2016.1245568
Shellhaas, R. A., Chang, T., Tsuchida, T., Scher, M. S., Riviello, J. J., Abend, N. S., Nguyen, S., Wusthoff, C. J., & Clancy, R. R. (2011). The American Clinical Neurophysiology Society’s guideline on continuous electroencephalography monitoring in neonates. Journal of Clinical Neurophysiology, 28(6), 611-617. https://doi.org/10.1097/wnp.0b013e31823e96d7
Sinha, S. R., Sullivan, L., Sabau, D., San-Juan, D., Dombrowski, K. E., Halford, J. J., Hani, A. J., Drislane, F. W., & Stecker, M. M. (2016). American Clinical Neurophysiology Society Guideline 1: Minimum technical requirements for performing clinical electroencephalography. Journal of Clinical Neurophysiology, 33(4), 303–307. https://doi.org/10.1097/wnp.0000000000000308
Stecker, M. M., Sabau, D., Sullivan, L., Das, R. R., Selioutski, O., Drislane, F. W., Tsuchida, T. N., & Tatum, W. O. (2016). American Clinical Neurophysiology Society Guideline 6: Minimum technical standards for EEG recording in suspected cerebral death. Journal of Clinical Neurophysiology, 33(4), 324–327. https://doi.org/10.1097/wnp.0000000000000322
Tatum, W. O., Selioutski, O., Ochoa, J. G., Clary, H. M., Cheek, J., Drislane, F. W., & Tsuchida, T. N. (2016). American Clinical Neurophysiology Society Guideline 7: Guidelines for EEG reporting. The Neurodiagnostic Journal, 56(4), 285-293. https://doi.org/10.1080/21646821.2016.1245576
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