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Waveforms & Findings


JME Typical irregular rapid 4-8 Hz Generalized Polyspike and slow wave complex; no close phase correlation between EEG spikes and jerks. Most pts are photosensitive. Could present normal interictal EEG with occasional frontally dominant 3-6 Hz s/w or ps/w.
Simple Febrile Normal interictally. Shows Sz type (usually TC). Photo sensitivity. Possibly occipital delta. Sz lasts up to 5 minutes. Post ictal shows slowing for up to 7-10 days.
Infantile Spasms Hypsarrythmia (mountainous arrhythmia), very high voltage, non-organized, mixed spike, polyspike, and sharp/slow waves - almost continuous.
LGS Typically very slow background with frequent high voltage discharges of 1.5-2 Hz sh/sl or s/w complex paroxysms with bifrontal predomination. Also Atypical Absence activity. Usually have multiple sz types also. EEG is consistent with sz type.
CJD Initiatial fragmented background. Rapid progress: bursts of distinctive mod voltage bi/triphasic sharp intervals at 700-900 ms, become increasingly periodic at 2-1 Hz or less/second (gen) and assoc w/ jerks. Eventual PLEDS and decreases before death.
BRE(C) (BECTS) Benign Rolandic Epilepsy of Childhood / Benign Epilepsy with Centro-Tempro Spikes Focal or biphasic spikes in the left or right Rolandic head regions (C3, C4, T3, or T4) independently during drowsiness. Can begin unilateral but shift hemispheres in a single recording.
Parkinson's Disease The incidence of EEG abnormalities is higher than in normal age individuals. The most common alteration is generalized slowing of the EEG. These patients with dementia have distinctly slower EEGs than patients without dementia.
CVA The EEG will show polymorphic delta activity with no fast background due to cortical damage. If damage is extensive, generalized slowing may present.
Stroke CVA (specifically) Focal slowing or polymorphic delta activity in area of involved blood vessel. Possible PLEDS or contralateral sz may develop.
Hepatic Encephalopathy In phases I & II, EEG may be normal. Stage III shows slowing with high voltage triphasic waves, typically 1.5-3 Hz and 150-300 uV, and bilaterally symmetrical with frontal predominance. Note: This pattern can be seen in other conditions as well.
Drug Toxicity / Overdose (AED) EEG shows diffuse slowing with excessive delta and theta activity.
Phenobarbital and Primidone Toxicity/Overdose (specifically) May show high voltage beta activity and slowing with rhythmic polymorphic delta, triphasic activity, or even alpha coma, burst-suppression or ECS.
Space Occupying Lesion Most common finding is focal 4-7 Hz theta with sh/sp focal activity and focal delta activity. Typical polymorphic delta waves (irregular configuration) appear in this region; presence of these waves are noticeably weaker in the contralateral hemisphere.
Rett's Syndrome Initially normal, variety abnormalities, intact background b/t 3-5 yo. B/t 5-10 yo, background slow, abn persists and paroxysmal high-amp theta frequent, due to spontaneous HV. 10yo+, reduction in abn activity but more slow background. Sleep- s/sp act.
Hypoxic Ischemic Encephalopathy EEG based on duration of O2 loss. Initially, slowing of alpha & increase of theta, followed by polymorphic delta activity & FIRDA. If situation continues, may decrease voltage and develop PLEDS, then burst-suppression, then ECS.
AIDS Dementia-like symptoms are associated with intermittent or continuous slowing, often most prominent anteriorly. Focal slowing or sharp activity can also be seen in pts with certain types.
Alzheimer's Disease The EEG findings depend on the progression of the disease. More prominent in later stages. As it progresses, the voltage decreases and alpha rhythm diminishes. Theta activity and some delta sharp waves become present (mostly in the temporal lobe).
Huntington's The EEG is normal in early stages. As the disease progresses, it is usually low voltage and shows a decrease in organized rhythms in later stages, along with specific movement types that cause artifact.
MS Normal or will show sz type of pt. Results found outside the reference range in some patients with this, but the findings are nonspecific. Nonspecific EEG abnormalities can be seen in normal individuals in the general population just the same.
Amyotrophic Lateral Sclerosis EEG changes are unusual and when they do occur, they are not very great. The most common cause of the alteration of the EEG is probably cerebral anoxia secondary to respiratory difficulty.
Kuru Usually normal EEG. Abnormalities, when present, consisted in slowing of alpha rhythm, increasing theta activity and slower waves and in some cases, prominent irregular delta activity. No indication of any repetitive complexes.
GSS EEG shows periodic synchronous discharges or similarities to CJD.
CP (Cerebral Palsy) EEG reflects type of brain injury. Can present: -Synchronous episodic sl wave act, regardless if clinical sz present. -Bisymmetrical abn mostly biparietal or bitemporal. -Gen abn were seen more often in serious cases than in focal or symmetrical cases.
Encephalitis / Brain Edema EEG reflects the injury type or presents on opposite hemisphere (coup / contrecoup injury).
Trisomy 21 EEG shows sz type, usually TC or IS. May also show: - Significant reductions in mean power of the alpha frequencies in posterior cortical regions - Diffuse Neuronal Dysfunction (DND).
FAS Reduced power, particularly in the alpha frequencies in the absence of significant slow activity. - More affected in the left hemisphere.
Fragile X The EEG frequently consists of diffuse neuronal dysfunction. Also moderate to high voltage mono or bi(di)phasic temporal or parietal spikes during slow wave sleep stages are common.
Sclerosing Panencephalitis May be normal or myoclonic szs develop. Pattern of prolonged discharges which include high voltage sh/sl waves for 4–7s then suppression for 1–4s; periodic complexes that consist of 4-5 sh waves every 2s, or interval of 5-5 1/2 p/sec. (burst-suppression).
Rubella The EEG typically shows focal slowing in the areas of effected cerebrum. As it progresses (spreads), it becomes generalized.
PWS Neuronal Dysfunction - Some patients present common EEG features of persistent high-amplitude 4-6 Hz activity in recordings during sleep, and while awake.
Angelman's Syndrome Persistent rhythmic 4–6 Hz activity exceeding 200 mV, often generalized, not associated w/ drowsiness, persisting for most of recording. No blocking w/ EC. Rhythmic delta act 2–3 Hz (200–500 mV) more prom ant w/ superimposed epileptiform discharges sp/sh.
Simple Partial Sz Interictal normal. Ictal and interictal discharges in the affected region (detected in depth recordings). As focal discharges spread, more likely to appear in the scalp EEG, but may produce ictal symptoms not accurately produced due to distance.
Partial Complex Sz Mostly act by non-Rem sleep & variable. Findings: -Rhythmic sp or sh/w then slowing -Slower sp/w act -Attenuation of amp -Rhythmic sl waves -13 to 30 Hz fast activity (hypersyncronous) -Sp/w complexes -Slowing/depression of voltage -No changes during sz.
Atypical Absence Sz Occipitally dominant spike and slow wave pattern of 2.5 or slower and is irregular and asymmetrical. Usually last longer than 5s. Interictally will be diffusely slow.
Typical Absence Sz Frontally dominant 3/s spike and wave activity and less than 5 seconds in duration.
Myoclonic Sz *Also see JME Brief bursts of generalized polyspike and wave activity that look very similar to muscle artifact, which are bilateral or generalized and synchronous, usually maximal in the frontal areas.
Atonic Sz No specific EEG pattern. Depends on sz type. Common finding is 1-4 Hz (predominant 2-3 Hz) generalized spike and wave or poly spike and wave discharges.
Tonic Sz Rapid spikes are resembling muscle activity are Hallmark. 2 common findings are: - Generalized fast activity called hypersyncronous, which is frontally dominant at 25 Hz (previously called beta band sz).
Clonic Sz Gen & Focal. Gen ictal shows gen s/w. Focal - Szs always associated w/ polysp/wave 1-3 Hz. At sz onset, ictal may consist of repetitive spiking for 5–30s, w/ continuous increase muscle tone. May evolve ictal polysp/wave complexes last to 3 min (CMAPs).
PGE - TC Normal interictal background. Ictal generalized abn discharges. May be interictal generalized sp/w or sp/sl wave, focal sp/w, or rapid 5 Hz gen sh/sl wave complexes. Post ictal shows flattening or low voltage for 1s - 1m. Residual can last 1-2 weeks.
SGE - TC Slow for age, poor organized, intermittent sp/sl waves, ictal abn discharges. May be multiple s/w patterns (ictal) then asymmetry (1-3s) then negative sp at 10Hz (about 10s) w/ interspersed sl waves that dissipate. Post ictal flat/low voltage for 1s-1m.
Status Epilepticus - TC Usually shows continuous bilateral though frequently asymmetric ictal discharges. Sometimes the presentation is subtle and difficult to recognize intermittent ictal activity.
Absence Status Epilepticus 2.5-3 Hz continuous spike and wave discharges. May have variations.
Complex Partial Status Epilepticus Convulsive type: EEG is the same as sz type, except nearly continuous.
Patterns or rhythms that characteristically appear in patient groups and are rarely seen in healthy subjects. Dysrhythmic Frequency
PLEDS that occur on in both hemispheres asymmetrically. BiPleds
Generalized Periodic Epileptiform Discharges (GPEDs) Very rare patterns and are classified as periodic short-interval diffuse discharges (PSIDDs), periodic long-interval diffuse discharges (PLIDDs) and suppression-burst patterns according to the interval between the discharges.
Positive Occipital Sharp Transients of Sleep (POSTS) Normal light and Stage II sleep patterns that have a positive polarity and sharp morphology. Can be rhythmic, triangular, synchronous, independent, and quite high voltage. Non-epileptiform.
Sleep Spindles 12-15 Hz activity in the central (more frontal in children) areas with some spread to frontal and parietal areas during light or Stage II sleep.
K-Complex Sleep transient in Stage II sleep, max over central areas and phase reversing at the vertex. Sometimes generated in response to stimuli such as noise, they are a compound waveform with a slow and superimposed fast component. Usually follows a spindle.
Lesions or Trauma can produce what abnormal finding following eye closure in children and young adults? Posterior Phi or Thi - per second rhythm.
Bancaudus Phenomenon When the background rhythm does not inhibit symmetrically, there is an abnormality on the side that does not. It is related to mental alerting in both hemispheres.
HA (Dysrhythmic Migraine, Hemicranial Migraine, S/F Lesion, Toxicity such as Meningitis or Encephalitis): Paroxysmal bursts of high voltage sharp and slow activity, having somewhat of an epileptiform appearance (DM), Focal slowing on side of HA (HM or S/F Lesion like tumor), Diffuse rhythmical slowing (toxicity), Normal (most common finding).
Head Injury Slowing or suppression of background activity over involved area or contralateral area (contra coup injury), non-specific dysrhythmic activity sometimes seen, or EEG can be normal.
Intensive Care Pts SE, high voltage diffuse slowing, Triphasic waves (metabolic), PLEDS, burst-suppression, diffuse alpha frequency, alpha coma, very low voltage activity, no discernible electrical activity, normal EEG.
Bursts A group of waves which appear and disappear abruptly and are distinguished from background activity by differences in frequency, form and/or amplitude. They are not always abnormal. Not a synonym of paroxysms.
Sharp and Slow Wave A sequence of a sharp wave and a slow wave. Can be referred to as Sharp and Slow Wave complex.
Triphasic Wave (TWs) Waves in 3 phases. Originally described as "blunted sp/w." High-amp (>70µV), + sharp transients preceded & followed by - waves of lower amp. Diffuse & bilat synchronous w/ bifrontal predom 1-2 Hz assoc. w/ wide range of toxic, metabolic, & structural abn.
Periodic Lateralized Epileptiform Discharges (PLEDs) Typically consist of sharp wave discharges focal or lateralized, repeating periodically or quasi-periodically at rates close to 1/s separated by intervals of quiescence. Often assoc. with continuous focal szs or depressed consciousness.
Burst-Supression A pattern characterized by bursts of theta and/or delta waves, at times intermixed with faster waves and intervening periods of relative quiescence. Note: this may be used to describe EEG effects of some anesthetic drugs at certain levels as well.
Delta < 4 Hz. Almost always indicates something focally pathological if seen in an awake adult. Or otherwise indicates a cerebral dysfunction.
Alpha 8-13 Hz. Principle background feature of adult, attenuates with EO. Posterior Dominant Rhythm (PDR) should be generally symmetrical but often higher amp in NON-dominant hemisphere (2:1 ratio acceptable). Absence on one side abnormal (poss infraction).
Beta 14+ Hz. In background of most pts. Max in fronto/centro. May be wide spread. Appears to increase amp during drowsy but could be attenuation of other frequencies. Some drugs increase it (CH, barbiturates, antidepressants. Assymetry can be pathological.
Theta 4-7 Hz. Usually some (about 5% or so) present in adult but may be completely absent. Local theta can indicate structural disease but err on side of normal.
Mu Rhythm (µ) Central (C3/C4) over motor strip. Can be unilateral, bilateral, symmetrical or asymmetrical. Sharp, 7-11 Hz (Greek letter) Mu shape, EO or drowsiness. Attenuates w/ mvt of opposite limb such as making fist or thinking about it. Normal variant.
Lamda Waves Transient sharp waves in the Occipital region. Brought out by scanning something with eyes. Normal variant. Probably a visual EP.
Sleep Activity Amplifies minor abnormalities and can bring out new abnormalities.
Stage I Sleep Focal sharps and spikes may show, as well as slowing, fragmentation, increased irregularity, decreased to no alpha, increased beta, diffuse theta in abundance with intermixed bifrontal delta in older pts. There may be early elements of the next stage.
Stage II Well defined (not fragmented or infrequent) Vertex sharp waves, K-Complexes, Positive Occipital Sharp Transients of Sleep (POSTS), Synchronous, rhythmic 12-14 Hz Sleep Spindles with potential max in the central, increased diffuse slow theta.
Stage III Slow Wave Sleep (SWS). Deep sleep. Increased diffuse theta, 50+% of record is clearly delta (may be very high voltage), progressive decrease in sleep spindles and may even be absent.
REM Stage Occurs about 90 minutes after onset of sleep. Eye channels (IO, SO, FP1, FP2, F7, F8) show irregular vertical and horizontal EM, background is low voltage theta.
SSPE Well known Rademecker Complex. Diffuse dysfunction & high voltage (300-1500uv) repetitive polyphasic sharp & slow waves lasting 0.5-2 secs and occurring regularly every 4-15 secs with posterior predom & assoc w/ myo jerks. Progresses, burst may decrease.
Children Variability of background is much more than adults. More generalized irregularity and slow waves. Slowing decreases with age. Need a true waking segment to distinguish drowsiness vs. actual slowing.
Birth No posterior rhythmic activity.
Infants (2-11 months) Background rhythm appears with rhythmic delta and then polymorphic delta to theta with gradual increase of frequency.
Age 1 Year Slow theta with intermixed delta.
Age 3 Years Fairly rhythmic theta and maybe a bit of alpha activity seen. Delta decreases and theta increases.
Age 6 Years Alpha rhythm is well established and frequency increases thereafter.
Age 7-8 Years Alpha rhythm reaches an average of 10 Hz. Some alpha delay may be normal. At this age, slowing becomes confusing. Err on side of normal unless there is a great amount of delta after age 4-5.
Elderly Background rhythm slows. Intermittent fronto/bitempro delta, symmetrical or asymmetrical is commonly found and is due to drowsiness or no reason at all. Sleep activity is less defined. Usually increased muscle artifact.
Hypnagogic Hypersynchrony Paroxysmal, high voltage, rhythmic, 4-5 Hz theta during drowsiness & sleep, diffuse distribution (max posterio/centro) occur in runs up to several seconds. Dramatic but normal and decreased after age 6, but can be seen in children 3 months-13 years.
Normal Variants - Fast or Slow Alpha 1/2 the frequency of the posterior background when notched appearance is present or twice the frequency in the occipital region and may alternate with alpha activity.
Normal Variants - Rhythmic Mid-Temporal Discharges (RMTD) Formally known as psychomotor variant. Sharp theta 5-6 Hz activity briefly (1 second or so) unilateral or independent, vary in amplitude. Rare and appears during drowsiness. *Note duration and frequency. Not clearly associated with seizure disorders.
Normal Variants - Wicket Spikes: Sharp, rhythmic, 7-11 Hz, mid-temporal max, different from RMTD in frequency and waveform. Seen during drowsiness. Shaped like Mu but different location (temp vs. centro/Rolandic).
Normal Variants - Subclinical Rhythmic Encepholographic Discharges of Adults (SREDA): Looks like ictal discharge. Unilateral or bilateral temporal/parietal. During wakefulness. Paroxysmal from normal background. Lasts several seconds with rhythmic theta and intermixed fast activity with no clear recruitment or decrease in consciousness.
Normal Variants - Small Sharp Spikes (SSS) or Benign Epileptiform Transients of Sleep (BETS): Low amplitude rapid spikes bihemispheric, synchronous or asynchronous, usually temporal during drowsiness or light sleep.
Normal Variants - Phantom Spike and Wave Discharges: Low voltage synchronous, 6 Hz parieto-posterio-temporo location. Spike is less prominent than the following slow wave. Can occur individually or in brief rhythmic runs.
Normal Variants - 14 & 6 Positive Spikes (Ctenoids): Maximum in posterior. Can occur in isolation or in groups, unilateral or bilateral. Two frequencies are mixed but one is maximum dominance. Seen during drowsiness and best when recorded with crossed ear reference (Ipsilateral).
Slowing Not abnormal unless it's focal or lateralized.
Focal Abnormality The most important is delta activity, which can be caused by tumor, infarct, abscess, subdural hematoma, hemorrhage, etc. If there is no pathology, it is a false localization.
Delta Focus Usually most evident in the temporal regions via projection.
Focal slowing and tumors: Less common in slow growing and more common in rapid growing.
Malignant, fast growing tumors: Irregular polymorphic delta at moderate amplitude that can vary with possible theta and beta involved. Does not usually show assorted spike and sharp wave activity.
What portion of the brain is usually affected when you see polymorphic activity? White matter.
What portion of the brain is usually affected when you see rhythmic activity? Grey matter, cortical or subcortal such as the thalamus.
Slow growing low-grade, non-malignant tumors, such as astrocytomas and meningiomas: Less prominent delta activity. Can produce theta (4-7 Hz) but may be normal or may have spike and sharp waves. Delta increases with size.
Very slow growing tumors like low-grade gliomas: No slowing until they become large.
Intra-ventricular tumors when located in the lateral ventricles: Slow wave focus in the adjacent temporal regions (false localization).
Intra-ventricular tumors when located in the 3rd ventricle: It may not show any focal slowing. May show rhythmic activity that is projected into the frontal or posterior head region, depending on it's location.
Brain Abcess Uncommon now days. Produces the most prominent and slowest polymorphic delta focus and less of the other rhythms. When it is chronic and encapsulated, it's slowing is much less prominent.
Diffuse Slowing Bilateral cerebral dysfunction suggested. Alzheimer, dementia, toxicity, metabolic, post-ictal, brain damage, etc. Determine by alertness - could also indicate drowsiness. Mark record at times of high alertness. Also med related, especially phych.
Projected Rhythms Rhythms at a distance. This indicates a deep midline structure process. Examples are FIRDA, OIRDA, TIRDA.
Frontal Intermittent Rhythmic Delta Activity (FIRDA): High voltage, frontal, rhythmic, irregular, intermittent at 2-3 Hz. Looks like repetitive eye blinks. Can be caused by tumors of the frontal lobe, increased cranial pressure, toxic metabolic conditions. Can indicate deep frontal/midline lesion or hydro.
Occipital Intermittent Rhythmic Delta Activity (OIRDA): High voltage, rhythmic, irregular and intermittent at 2-3 Hz. Usually seen with lesions from the posterior 3&4 ventricle.
Temporal Intermittent Rhythmic Delta Activity (TIRDA): High voltage, rhythmic, irregular and intermittent at 2-3 Hz. Temporal lesions. These affect the ventricles laterally.
Periodic Lateral Epileptiform Discharges (PLEDs): Caused by focal lesions, infarcts (adjacent), malignant neoplastic lesions, abscesses, encephalitis, sometimes Herpes Simplex virus. Not by slow growing tumors. High voltage sharp waves continuous every 1-2 seconds. Unreactive. Variable sz indication.
Periodic Epileptiform Discharges (PEDs): Generalized, reoccurring every 1-few seconds, varies in form by synchronous high voltage sharp or spike waves, indicative of subtle or generalized status and associated with coma, minor motor manifestations, can be the result of anoxia.
Electroretinogram (ERG): A normal response of the retina to PS. Low voltage in anterior head regions. Can be confused with abnormal frontal sharps. To distinguish the photoelectric effect, cover electrodes w/ cloth. High rates of Intermittent PS (IPS) will fatigue response.
Burst Suppression: Marked depression w/ bursts of act in variable amplitude, duration, waveform. Multiphasic delta mixed with various frequencies or epileptiform like spike/sharp waves. Can be found in general anesthesia, anoxia, or head trauma. Poor prognosis esp in GCSE.
Epileptiform Activity Only spikes, sharps, and spike and wave complexes.
Spike 20-80 ms. Often followed by a low voltage slow potential (200 ms). Can be focal, multifocal, or generalized. Looks like it can prick your finger but is slower than muscle potentials.
Spike and Wave Complex 2 components. Spike and time locked slow wave (like Absence - 3 Hz). Also classically seen in LGS, TC, and JME.
Sharps Not definite epileptiform activity but similar when pt has epilepsy. Duration 80-200 ms. Upswing should be steeper than downswing. Usually less focal than a spike.
Are Delta and Theta activity considered epileptiform? Some bursts are sometimes seen in pts being tx for sz types but not necessarily.
Do spike or sharp waves independently or in complexes indicate epilepsy? No. It can be there for various reasons, such as indicating drowsiness, delayed reaction time, or even be a normal variant.
What type of activity is usually seen in Classic Migraines? Sharp waves in the temporal region.
What type of activity is usually seen in Complex Migraines? Spike and wave discharges.
What is the most common site for spikes to be seen? Temporal.
If a spike is maximal at F7 & F8, what does this usually indicate? CPE, but could also be a focus in that area.
What does abnormality in the posterior temporal areas indicate? Damage more posteriorally, such as infarct in posterior head region.
What do occipital spikes usually indicate? Occipital epilepsy, usually in children. It is distinctive and has visual symptoms (hallucinations may be CP) and a favorable dx.
What is the challenge in reading occipital spikes? They usually blend into the background. Need to read with EO & EC.
What is the best montage to view occipital spikes? Hatband because it goes through the occipital head region. Reference does not change direction, only increases amplitude. It will show a downward deletion in a bipolar montage and no phase reversal because it's at the end of chain.
Centro-Tempro Spikes Can accompany BECTS/Rolandic Epilepsy, distinctive, focal in the central head region, may spread to T3 & T4. Usually biphasic spikes with variable amplitude that increases during drowsiness & sleep. Compared to V-waves, are more temporal and independent.
Frontal Spikes Sz originates in the frontal lobe. This activity is seen adjacently with no phase reversal due to end of chain. Hatband montage is best. This activity is usually more unilateral than eye blinks.
Secondary Bilateral Synchrony (SBS) Seen in pts with frontal lobe epilepsy. Irregular spikes that precede general spike and wave activity as in secondary generalization.
Midline Spikes During sleep, sharps are considered normal but this is not.
Hypsarrhythmia IS. Mountainous arrhythmia. Continuous generalized, high voltage, chaotic slow waves and multifocal and varying sharps and spikes with occasional generalization and accompanied by clinical spasms called Salaam attracts and then attenuation with beta.
Electrodecremental Response Intermittent generalized attenuation usually seen in IS and sometimes LGS.
Complex Febrile Szs between 5-15 minutes. Focal and reoccurring within a 24 hour period. No EEG correlation.
Absence During Sleep Frequent slowing. 3 Hz/s Spike and wave complexes become poly spike and wave complexes.
Non-Epileptic Seizures (NES) (Pseudoseizures) - Except SPS Increased and discontinuous muscle activity without preceding spikes. Looks like TC sz clinically. May have abnormal EEG w/ spikes and sharps (20% are epileptic) but not continuous during muscle activity. Alpha seen and no post-ictal slowing.
Non-Epileptic Seizures (NES) (Pseudoseizures) and SPS Difficult to determine because only 1/4 of true szs can be detected by scalp electrodes. From mesial (toward midline) frontal. Transverse bipolar montage is best and should be dx clinically as opposed to EEG.
5 Stages of GCSE Progression - Stage 1: Repeated, discrete sz activity including rhythmic, rapid generalized, high voltage spike and waves averaging about 2.5-3 Hz/s without full recovery before the next.
5 Stages of GCSE Progression - Stage 2: Merging, discrete patterns. I.E: Polymorphic spike and wave interrupted by rhythmic waves of varying frequency, waxing and waning of amplitude. In a comatose pt, minor (may be very brief) or no clinical movements.
5 Stages of GCSE Progression - Stage 3: Continuous ictal activity, generalized spike and wave and minor or no clinical convulsions due to not waking from continuous sz.
5 Stages of GCSE Progression - Stage 4: Burst-Suppression. A very poor prognosis.
5 Stages of GCSE Progression - Stage 5: High voltage generalization with a PLEDS domination and a flat background. This indicates that it has progressed far too long and the outcome depends on the underlying disease process.
NCSE Two types: Absence and CP. May show mixed activity with common bifrontal predominance.
What pattern can indicate Intercranial Pressure (ICP)? FIRDA.
Multi-Infarct Dementia (MID) Similar to Alzheimer's clinically and in EEG but more likely to show assymetry and focal activity (as result of nature of disease). Sometimes 'psudoperiodic discharges' are seen and can suggest possible CJD.
Pick's Disease Mostly focal slowing in the frontal/temporal head regions from early on.
Ischemic Stroke Irregular polymorphic delta focus in involved hemisphere, maximal in the frontal, temporal, and parietal head regions. May be rhythmic delta mixed with posteriorally dominant rhythm disrupt. With resolution, gradual decrease in slow wave focus.
Edema Mostly widespread abnormality.
Cerebral Artery Occlusion Frontal slowing with or without rhythmic delta on involved hemisphere.
TIA Appropriate focal/localized slowing. Normal after resolution.
Hemorrhagic Stroke Highly variable EEG depending on area and state of awareness. Mild: minor slowing. Deep: marked bilateral delta unless conscious - then no assymetry. Bifrontal delta is common.
Subdural Hematoma (SDH) Asymmetric ND in the involved hemisphere (classic) with beta activity and disturbed or absent alpha.
Metabolic Disorders EEG lags behind resolution. Hallmark is ND. Progression: 1. PDR slowed and disrupted or absent. 2. Slowing varies depending on conscious level. Usually symmetrical unless cause is a focal lesion unrelated to this disorder. 3. Triphasic. (Test arousal.)
What is Anterior to Posterior (AP) delay? The frontal component leads the posterior component by 100 ms or so.
NCSE vs. Coma There is some nystagmus seen in the first.
Hypoglycemia Multifocal spikes with focal onset szs and occasionally triphasic waves. Correction returns to normal.
Hypothyroidism Slowing of PDR and some ND. No epileptiform activity.
Coma Depends on underlying cause. There is usually ND from brain damage. There are frequency-specific states such as alpha and theta, which is predominantly frontal but diffuse. No response to stimuli.
Anoxia PLEDS, Burst-Suppression, or any GCSE.
What is the #1 key when considering abnormalities in diseases or conditions? The findings progressively decrease, so they can be normal depending on awareness level.
Phantom Spike and Wave (PhSW) A low amplitude and often unclear spike within a repeating spike and slow wave complex. The spike is 6 Hz/second. Since the spike is unclear, the wave appears to be a paroxysmal 6 Hz/second. Morphology is 'mini' 3/second generalized and may have notches.
How much temporal delta is acceptable as normal in adults? Not more than 5%.
When is it normal to see temporal slowing? In children and elderly.
Barbiturates Increased amt / frequency of beta, increased theta amp with frontal predom, PDR decreases as level increases. Intoxication = no decreased beta but increased delta, then burst-suppression, then flat. Abrupt withdraw = asynch slowing and gen epi activity.
Benzodiazepines Increased beta (for days after 1 dose) and attenuation of PDR. Paroxysmal synchronous slowing with long term use. Toxic = similar to CNS depressants and correlates with mental status.
Neuroleptics (Typical & Atypical) Slowing of PDR and DND. May activate generalized paroxysmal slow waves and sharps, and Clozapine (atypical) may increase sz frequency. Risperidone has no effect on EEG.
Lithium Diverse prom changes. Slowing of PDR, ND, intermittent rhythmic delta in frontal / occipital, sometimes triphasic, occipital spikes, focal slowing (this is not s/f lesion). Intox = DND. Triphasic, multifocal epileptiform act. May stay long after d/c.
Tricyclic Antidepressants Increased beta and theta, decreased PDR, paroxysmal slow waves or even spikes in therapeutic doses. Sz frequency may increase or cause sz in non-sz pts. Acute intox may produce widespread, poorly reactive alpha range activity and spikes.
AEDs Phenytonin = no prom beta but increased DND theta range, decrease PDR w/ chronic use. Toxic = diffuse irr delta, parox rhythmic slow waves. Carbamazepine: Toxic can = diffuse slowing. Epi act is not altered but may increase spikes.
Valproic Acid (VA) No change or decrease in background at therapeutic. This is the anti spike and wave drug. Used to decreased generalized epileptiform activity, particularly 3 Hz s/w. Toxic = encephalopathy changes, diffuse delta with rare epilepsia partialis continua.
Blocking The same as attenuation.
Extreme Spindles Very high voltage, usually seen in mental impairment.
Rhythmic Temporal Theta Rhythmic 4-7 Hz during drowsiness. May be notched. Normal variant. Formally known as Psychomotor variant.
Sigma Rhythgm Another name for Sleep Spindles.
Posterior Slow Waves of Youth (Mittens) Sharp delta activity in the posterior head region that is prominent in children and adolescence and attenuates with EO. Thalamus related.
Slow Alpha Varient Can be half the frequency and usually appears notched.
Vertex Sharp Wave (V-Wave) Seen during Stage I-II sleep at the vertex but may be slightly posterior. Bilaterally synchronous.
What does BECTS stand for? Benign Epileptic Central-Temporal Spikes.
BECTS are the same as... BRE
Typically, what is the voltage for Absence Szs? Around 500 uv.
Typically, what is the voltage for LGS S/W activity? Around 600 uv.
Is FIRDA rhythmic frontal activity? No, there is a difference between the two.
Simple Partial Duration: 5-10s, LOC - no, postictal confusion - no, sz shows focal spikes or normal.
Complex Partial Duration: variable, 5-10s, 1-2m, rarely 5m +, LOC - yes, postictal confusion - yes, sz shows focal activity spreading to involve one or both hemispshers.
Absence Duration: 5-10s - may cluster, LOC - yes, postictal confusion - no, sz shows generalized 3/s spike and wave.
Generalized TC Duration: 1-2m, LOC - yes, postictal confusion - yes, sz shows series of generalized, high amplitude spikes.
GSW Generalized Spike and Slow Wave.
In BRE, what does 'Psudoslowing; mean? A normal background with Rolandic spikes and when spikes occur frequently, may be accompanied by focal slowing in that area. This usually occurs during sleep.
Doose Syndrome (Myoclonic-Astatic Epilepsy MAE) Hallmark features are rhythmic partially accentuated 4-7 Hz background seizure activity develops early in the course.
Slow Waves Any activity slower than the low range for normal at a given range. Can be area dominant or generalized and considered significant depending on frequency, location, and distribution.
Posterior Dominant Slow Waves In the young, this is common and normal. Common in mild head injury. If paroxysmal theta or delta, can indicate a sz problem of the posterior fossa structures.
Anterior Dominant Slow Activity Is of greater diagnostic significance if alpha and other frequencies are preserved. When alpha activity is slowed in the presence of this, it is frequently correlated with electrolyte imbalance, metabolic disturbance, or toxic encephalopathy.
Paroxysmal Frontal Slow Activity Often a projected disturbance from midbrain. Waves may vary from 2-4 Hz. May appear sinusoidal and may not be associated with spike or wave activity.
Slow Waves Associated with Space Occupying Lesions Frontal pole lesions in general, usually with bilateral or fairly synchronous slowing. Asymmetry or asynchrony tends to be more common with unilateral lesions than with diffuse (chemical or toxic). These waves tend to be less than 3 Hz.
Bi-Frontal Theta Slowing With well preserved alpha, may be continuous or paroxysmal and suggests lesions involving the anterior thalamus and/or hypothalamus area. Also commonly seen in puberty as a normal variant. Occasionally can be seen in TLE but more flat top morphology.
Uni-Focal Spikes Can be due to superficial or deep cortical or thalamic lesions. If thalamic, spikes may be bilateral but if only one side, spikes will be higher voltage on that side. The abnormal discharge may be some distance from site. Determined by phase of spike.
What do spikes indicating a distant foci look like? In general, have a significant positive phase or may be multi-phasic.
Bilateral Spikes If symmetrical and synchronous, may be due to symmetrical lesions. Ex: birth injuries affecting both temporal lobes.
Mirror Focus May be symmetrical & synchronous but may originate from primary lesion of opposite side with rapid pass through corpus callosum. Primary can be localized because it fires independently initially. After years, ir can 'learn' to fire independently.
Multi-Focal Spike Discharges Common in children with mental impairment with or without szs. Younger than 3 years of age, prognosis is poor. Can be seen in middle age with rare primary epilepsy, then more diffuse, sporadic, and low voltage than young. Often only present in sleep.
Hemispheric Foci Spikes that appear to involve only one entire hemisphere. Predominantly seen in children and usually due to diffuse hemisphere damage with atrophic changes in the cortex.
Nearly all spikes at the cortical surface have what polarity? Negative.
Spike foci occur most frequently in what group? Children.
What age group has the highest percentage of spike foci? The first year of life.
Of all children with spike foci on the EEG, what percentage has a hx of szs, present of past? Less than half.
Possible EEG findings in Congenital Disorders... Asymmetries, BSSW (Bilaterally Synchronous Spike and Wave Discharges), LSW (Localized Sharp Waves), Generalized 3 Hz Spike & Wave complexes, Generalized Polyspikes, Generalized Spike & Wave complexes.
Ciganek Rhythm (Midline Theta Rhythm) Seen in awake or drowsy states. Variable reactivity to eye opening. Distribution: CZ (midline - vertex) Waveform: smooth, sinusoidal, slightly sharply contoured, rhythmic, arciform, spiky, or mu-like. 4-7 Hz. Normal variant.
Another name for Delta Brush... Ripples of Prematurity.
Another name for Wicket Spikes (Waves)... Temporal Alpha Activity.
Phantom 6 Hz Spike and Wave - Female: FOLD: Occipital, low amplitude, drowsiness. Normal variant.
Phantom 6 Hz Spike and Wave - Male: WHAM: Waking, high amplitude, frontal. Normal variant.
LKS No typical pattern of abnormal activity absolutely differentiates this syndrome. Typically, abnormalities are seen in the temporal or parietal areas and can be either bilateral or lateralized to either hemisphere. Usually seen in sleep.
Reye's Syndrome Diffuse slowing in phase II. Triphasic waves as progresses.
Phenytonin Slowing of alpha then alpha assymetry. Progression leads to generalized slowing. Reversible with detoxification.
Herpes Simplex Virus (HSV) - Herpes Encephalitis Virus (HES) Focal slowing, Focal temporal delta, Lateralized polymorphic delta, Diffuse slowing, spiking, PLEDS.
SREDA Typically 5-6 Hz. Location is widespread or bilateral with a posterior maximum. Morphology is seizure-like (ie, rhythmic sharply contoured theta). Abrupt onset and termination may help distinguish from Sz. Duration from 20 s to m (average, 40-80 s).
Created by: kmburg5840
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