Study guide
7.3 Neurological Disorders & EEG Correlation
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
7.3 Neurological Disorders & EEG Correlation
Key Takeaways Explain This Topic AI
Focal destructive lesions (tumor, infarct, abscess) produce continuous polymorphic focal delta over the lesion, while diffuse processes (meningitis, anoxia, toxic-metabolic states) produce generalized slowing.
Herpes simplex encephalitis classically produces lateralized periodic discharges (LPDs/PLEDs) over the temporal region, an important critical-value pattern to recognize and escalate.
Toxic-metabolic encephalopathies (hepatic, uremic, anoxic) produce generalized slowing and triphasic-morphology generalized periodic discharges that are typically reactive to stimulation.
Creutzfeldt-Jakob disease classically produces periodic sharp-wave complexes about every 0.5-1 second, and requires single-use electrodes and prion-specific handling.
The technologist correlates the clinical history with the recording, documents reactivity and state, applies seizure precautions, and notifies the provider of critical findings without rendering a diagnosis.
Last updated: June 2026
Why Clinical Correlation Is on the Exam
The content outline explicitly lists neuropathology (tumors, encephalopathy, vascular), neurological disorders, head trauma/TBI, psychiatric disorders , and correlation of history with EEG patterns . The technologist is the person who reads the order, takes the history, watches the patient, and records the tracing simultaneously - so the exam tests whether you can connect the clinical picture to the expected EEG and recognize when a finding is a critical value that demands provider notification.
The guiding principle: a focal, fixed, polymorphic abnormality points to a structural lesion; a diffuse abnormality points to a global process (toxic, metabolic, anoxic, infectious, degenerative).
Structural and Vascular Lesions
Disorder Characteristic EEG Correlate
Brain tumor (e.g., glioma) Continuous focal polymorphic delta over the lesion; possible focal attenuation; may have focal spikes
Ischemic stroke / infarct Acute focal slowing/attenuation; may evolve LPDs in the acute period
Intracerebral / subdural hemorrhage Focal slowing or attenuation; a subdural may attenuate overlying fast activity
Cerebral abscess Focal slowing, sometimes with focal periodic discharges
Head trauma / TBI Focal or diffuse slowing depending on injury; skull defects cause a breach rhythm (locally higher-amplitude, sharper fast activity over the defect - a normal consequence of the skull opening, not epileptiform)
The breach rhythm is a classic exam point: over a craniotomy or skull defect, the missing bone no longer attenuates the signal, so activity is higher in amplitude and sharper locally. It is a normal physical effect of the skull defect and must not be called epileptiform.
Diffuse and Metabolic Encephalopathies
A frequent sample-question theme is which processes cause diffuse slowing . The answer is the global ones - meningitis, encephalitis, anoxia, and toxic-metabolic states - whereas a focal mass (meningioma, abscess, thrombosis) tends to cause focal slowing.
Toxic-metabolic encephalopathy (hepatic, uremic/renal, hypoglycemic, anoxic): generalized theta/delta slowing; triphasic-morphology generalized periodic discharges (GPDs) are classic in hepatic and renal failure and are typically reactive to stimulation (which helps distinguish them from epileptiform discharges).
Anoxic brain injury (post-cardiac arrest): generalized slowing, burst-suppression , GPDs, or in the worst case electrocerebral inactivity - patterns with major prognostic weight, so accurate, reactive-tested recording is critical.
Infectious and Degenerative Disorders
Disorder Characteristic EEG Correlate Technologist Note
Herpes simplex encephalitis Lateralized periodic discharges (LPDs/PLEDs) over the temporal region, often every 1-4 s Critical value - recognize and escalate; temporal localization matters
Creutzfeldt-Jakob disease (CJD) Periodic sharp-wave complexes ~every 0.5-1 s on a slow background Use single-use electrodes and prion handling; routine disinfection does not inactivate prions
Subacute sclerosing panencephalitis (SSPE) Periodic high-voltage complexes every 4-15 s time-locked to myoclonic jerks Long interval is the clue; correlate with myoclonus
Meningitis / diffuse encephalitis Generalized slowing; possible periodic patterns Diffuse, not focal, unless a focal complication develops
The periodicity interval is a high-yield discriminator: ~0.5-2 s for LPDs and CJD, but much longer (4-15 s) for SSPE. Knowing the interval lets the technologist describe the pattern accurately for the reader.
Other Conditions and Their EEG Relationships
Narcolepsy: characterized by sleep-onset REM periods (SOREMPs) - REM appearing abnormally early after sleep onset. (A classic sample-question answer is 'REM onset sleep.')
Psychiatric disorders: the routine EEG is often normal in primary psychiatric disease; the EEG is frequently ordered to exclude an organic or epileptic cause. The technologist should not expect a specific 'psychiatric' pattern.
Dementias (e.g., Alzheimer disease): generalized slowing and loss of the normal posterior rhythm in advanced disease; early disease may be near-normal.
Migraine, syncope, nonepileptic events: the EEG helps distinguish these from seizures; capturing a typical event with no ictal correlate is itself diagnostically valuable - documenting that a 'spell' had no EEG change supports a nonepileptic diagnosis.
Sleep disorders: narcolepsy's SOREMPs are detected on the multiple sleep latency test; the technologist who records sleep must label stages accurately because the clinical question often hinges on sleep architecture.
Basic Cardiac Rhythms and the EEG
The outline lists basic cardiac rhythms and rhythms associated with EEG changes because cardiac events masquerade as neurologic ones. A simultaneous ECG channel is standard so the reader can correlate. A cardiac arrhythmia or asystole can cause a convulsive syncope with diffuse EEG slowing/attenuation that recovers when perfusion returns - distinguishing this cerebral hypoperfusion pattern from a primary seizure is a classic correlation point.
The technologist should recognize that a regular sharp deflection time-locked to the QRS is cardiac artifact , not cerebral activity, and that a sudden diffuse attenuation coinciding with a dropped heartbeat points to a cardiac cause.
The Technologist's Correlation Responsibilities
Clinical correlation is an active recording task , not after-the-fact interpretation:
Extract the clinical question from the order and history so the recording targets it (montage, activations, duration, extra electrodes).
Test and document reactivity (response to eye opening, noxious or auditory stimulation) - especially important to separate reactive metabolic GPDs from epileptiform patterns and to assess comatose patients.
Apply seizure precautions and ensure patient safety when a seizure or high-risk pattern is anticipated.
Recognize critical values - electrographic seizure, status epilepticus, herpes-pattern temporal LPDs, new burst-suppression, deterioration - and notify the provider promptly.
Annotate, do not diagnose: describe what you see ('continuous left temporal polymorphic delta, non-reactive') and let the physician assign the clinical meaning.