Study guide
6.1 High-Yield Recap
ABRET Registered EEG Technologist R.EEG.T.
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1 Introduction & R.EEG.T. Exam Overview
1.1 R.EEG.T. Exam Facts 1.2 Eligibility & Pathways 1.3 Content Outline & Study Strategy
2 Neurophysiology & Instrumentation
2.1 Neuroanatomy & Neurophysiology 2.2 Electronics & Instrumentation 2.3 Montages & Derivations
3 Pre-Study & Patient Preparation
3.1 Patient History, Assessment & Safety 3.2 Electrode Application & the 10-20 System 3.3 Equipment Setup & Calibration
4 Performing the Study
4.1 Recording Technique & Documentation 4.2 Activation Procedures 4.3 Special Studies & Populations
5 EEG Patterns, Artifacts & Recognition
5.1 Normal EEG Patterns 5.2 Abnormal Patterns 5.3 Artifact Recognition & Elimination
6 Clinical Correlation & Seizure Disorders
7.1 Seizures, Epilepsy & Syndromes 7.2 Neonatal & Pediatric EEG Patterns 7.3 Neurological Disorders & EEG Correlation
7 Post-Study Procedures & Professional Practice
8.1 Post-Study Procedures & Documentation 8.2 Ethics, Safety & Professional Issues
8 Final Review & Test-Day Strategy
6.1 High-Yield Recap 6.2 Localization & Pattern Drills 6.3 Test-Day Strategy & Pitfalls
6.1 High-Yield Recap
Key Takeaways Explain This Topic AI
The International 10-20 System spaces electrodes at 10% and 20% of the nasion-inion and preauricular distances; odd-numbered electrodes are left, even-numbered are right, and 'z' electrodes (Fz, Cz, Pz) sit on the midline.
Common Mode Rejection Ratio (CMRR) of at least 100:1 (40 dB) and the Nyquist rule (sample rate at least twice the highest frequency of interest) are core instrumentation facts the R.EEG.T. exam tests directly.
In a bipolar (longitudinal) montage, a phase reversal points to the channel pair where the maximal voltage is located, localizing the source between the two reversing electrodes.
Hyperventilation runs 3-5 minutes and photic stimulation sweeps roughly 1-30 Hz; normal variants such as wicket spikes, rhythmic mid-temporal theta of drowsiness (RMTD), and 14-and-6 positive spikes are benign and must not be over-read as epileptiform.
Physiologic artifacts (eye, muscle, ECG, pulse) follow the patient; technical artifacts (electrode pop, 60 Hz mains, salt bridge) follow the equipment - resolving impedance and connections fixes most technical artifacts.
Last updated: June 2026
Why a Cross-Domain Recap Matters
The ABRET (American Board of Registration of Electroencephalographic and Evoked Potential Technologists) R.EEG.T. exam is a 4-hour computer-based test weighted 25% Pre-Study/Patient Preparation and 75% Performing the Study . Most missed questions are not from a single weak topic - they come from blending concepts: reading a montage without first confirming the calibration , or calling a benign normal variant epileptiform. This recap stitches the domains back together so you can answer integrative items quickly.
Electrode Measurement & Nomenclature
The International 10-20 System places electrodes at distances of 10% and 20% along the nasion-to-inion (front-back) and preauricular (ear-to-ear) measurements. Memorize the rules so a single labeled electrode tells you its hemisphere and region.
Odd numbers = left hemisphere; even numbers = right hemisphere.
The letter z (Fz, Cz, Pz, Oz) marks the midline .
Letters encode region: Fp = frontopolar, F = frontal, C = central, T = temporal, P = parietal, O = occipital, A = auricular (reference).
Lower numbers sit closer to the midline; higher numbers sit more laterally.
Topic to Must-Know Table
- Topic Must-Know Fact
- 10-20 measurement Cz is the true vertex - 50% of both nasion-inion and preauricular distances
- Electrode count A standard adult routine montage uses 21 electrodes (19 active + 2 references)
- Impedance Keep electrode impedance balanced and generally below 5 kilohm; mismatched impedance degrades CMRR
- CMRR At least 100:1 (40 dB); higher CMRR rejects more common-mode noise like 60 Hz
- Nyquist Sampling rate must be at least 2x the highest frequency of interest to avoid aliasing
Filters Low-frequency (high-pass) filter ~1 Hz; high-frequency (low-pass) filter ~70 Hz; notch only as a last resort
Phase reversal In a bipolar chain, pen deflections pointing toward each other localize the maximal-voltage electrode
- Sensitivity Routine adult EEG ~7 microvolt/mm; lower sensitivity number = larger displayed amplitude
- Paper/sweep speed Standard display equals 30 mm/sec (10 sec per page)
Hyperventilation 3-5 minutes; build-up (slowing) is normal, especially in children; contraindicated in recent stroke, sickle cell, severe cardiopulmonary disease
Photic stimulation Flash frequencies roughly 1-30 Hz; a true photoparoxysmal response is generalized and outlasts the stimulus
Normal variants Wicket spikes, RMTD, 14-and-6, SREDA, benign sporadic sleep spikes, mu rhythm - benign, not epileptiform
Epileptiform Spikes (under 70 ms) and sharp waves (70-200 ms) that disrupt background and have an after-going slow wave
- Sleep markers Vertex waves and sleep spindles/K-complexes mark N2; slow-wave (delta) dominates N3
- Artifacts Physiologic artifacts follow the patient; technical artifacts follow the equipment
- Instrumentation Limits in One Pass
The differential amplifier subtracts input 2 from input 1 and amplifies the difference. Signals common to both inputs (like 60 Hz line noise) are mostly canceled - this is common-mode rejection , quantified by the Common Mode Rejection Ratio (CMRR) . Equal electrode impedances are what let the amplifier 'see' the noise as common; a single high-impedance electrode unbalances the inputs and lets 60 Hz through. The fix is re-prepping the electrode, not reaching for the notch filter.
Digital EEG must obey the Nyquist theorem : the sampling rate has to be at least twice the highest frequency you want to record, or fast activity aliases into false slow waves. A 256 Hz sample rate faithfully captures content up to 128 Hz.
Localization Logic
Phase reversal is the single most tested localization concept. In a bipolar (longitudinal 'banana') montage , electrodes are linked in chains. A negative cortical source produces an upward (by EEG convention, negative-up) deflection in the channel where it is input 1 and a downward deflection where it is input 2. The electrode shared by the two channels whose pens point toward each other (or away, for a positive field) is the site of maximal voltage. In a referential montage , the channel with the largest amplitude marks the maximum - no phase reversal is needed.
Normal Variants vs. Epileptiform
Benign variants mimic pathology but lack the disruptive, evolving character of true epileptiform discharges. Key distinguishing features:
Wicket spikes : arciform temporal waves in drowsiness; no after-going slow wave, no background disruption.
RMTD (rhythmic mid-temporal theta of drowsiness) : 4-7 Hz notched theta runs, monomorphic, no evolution.
14-and-6 positive spikes : surface-positive arch bursts in sleep, often in adolescents.
SREDA (subclinical rhythmic EEG discharge of adults) : theta runs without clinical seizure or post-ictal slowing.
True epileptiform discharges disrupt the background, have a steep rising phase, and are typically followed by a slow wave.
Seizure and Clinical-Correlation Recap
Under the ILAE 2017 framework, seizures are classified by onset (focal, generalized, unknown). High-yield electroclinical pairings: 3-Hz spike-and-wave = childhood absence (HV-activated); 4-6 Hz polyspike-and-wave, photosensitive = juvenile myoclonic epilepsy; hypsarrhythmia = infantile spasms/West syndrome; slow (<2.5 Hz) spike-and-wave = Lennox-Gastaut; anterior temporal sharp waves (F7/F8, T1/T2) = mesial temporal lobe epilepsy.
For disorders: focal polymorphic delta = structural lesion; diffuse slowing = global/metabolic process; temporal LPDs/PLEDs = herpes encephalitis; triphasic GPDs (reactive) = hepatic/uremic encephalopathy; periodic sharp complexes ~1/s = CJD.
Neonatal/Pediatric Recap
Interpret neonates by conceptional (postmenstrual) age . Continuity matures: trace discontinu (very premature) -> delta brushes prominent (~28-34 wk) -> trace alternant in term quiet sleep -> continuous slow-wave sleep. Normal graphoelements (delta brushes, encoches frontales, occasional temporal sharps) are not epileptiform. Neonatal seizures are often subtle/electrographic-only and focal. The PDR matures ~4 Hz (4 mo) -> 6 Hz (12 mo) -> 8 Hz (3 yr) -> 9-10 Hz (~8 yr).
Post-Study and Ethics Recap
Post-Study (19%): clean before disinfect; single-use electrodes for non-intact skin/prion risk; write an accurate technical report of observations (not a diagnosis); save/back up/archive raw data (ACNS Guideline 4, HIPAA). Ethics (20%): HIPAA minimum-necessary disclosure to authorized care team only; one patient ground + isolated equipment + leakage-current limits; collodion/acetone are flammable - follow SDS/OSHA ; the Code of Ethics forbids falsifying or omitting data.