EEG & qEEG

Criteria & assessment

• Present: clear persistent segment >=1 continuous min with lower-voltage/faster anterior and higher-voltage/slower posterior activity.
• Reversed: same duration and paired criteria in the opposite direction.

Criteria & assessment

• Qualifying change may be in cerebral voltage or frequency, including attenuation.
• SIRPIDs-only: sole response is a stimulus-induced rhythmic, periodic, or ictal-appearing discharge.
• Unclear: inadequate test, excessive artifact, or equivocal cerebral change. Unknown: not tested or maximally alert throughout.

Criteria & assessment

• Mild: consistent voltage difference <50% on an appropriate referential recording or frequency difference 0.5–1 Hz.
• Marked: voltage difference >=50% or frequency difference >1 Hz.
• Consistent means >80% of relevant instances or record.

Criteria & assessment

• High: most/all activity >=150 µV.
• Low: most/all activity <20 µV but not suppressed.
• Suppressed: all activity <10 µV.
• For nearly continuous/discontinuous records, use the higher-voltage portion.

Criteria & assessment

• Present: higher amplitude and increased sharpness, mainly faster frequencies, versus the rest of brain and especially the contralateral homologous region.

Criteria & assessment

• Focal (L/BI/UI/Mf) or generalized rhythmic activity >4 Hz, at least six waves at a regular rate, duration >=0.5 s and <10 s.
• Exclude known normal/benign patterns, activity forming part of burst-suppression/attenuation, and definite clinical correlates.
• Definite: evolution OR morphology AND location resembling interictal discharges or seizures in the same patient.
• Possible: sharply contoured without either definite criterion.
• Paroxysmal fast activity of the stated duration can qualify, focal or generalized, subject to the defining exclusions.

Criteria & assessment

• Burst averages >=0.5 s and has >=4 phases (>=3 baseline crossings); maximum duration 30 s.
• Report location as generalized, lateralized, bilateral independent, unilateral independent, or multifocal; report typical burst/interburst durations and sharpest component.
• Highly epileptiform: >=2 spikes/sharp waves in most (>50%) bursts at mean >=1 Hz within a burst, where frequency = 1 / typical interpeak latency; alternatively a rhythmic potentially ictal-appearing pattern occurs in most (>50%) bursts. Table 1 states >=1 Hz for this alternative, while A.4.d does not repeat that cutoff. Record frequency and location.
• Identical: first >=0.5 s of each burst, or each stereotyped cluster of >=2 bursts, is visually similar in all channels in most (>90%) bursts.

Criteria & assessment

• Attenuation: lower activity >=10 µV and <50% of higher-voltage background; suppression: lower activity <10 µV.
• Continuous: low-voltage percent <1%.
• Nearly continuous: 1–9%, with qualifying periods >=1 s; report typical duration.
• Discontinuous: alternating higher activity with 10–49% attenuation/suppression.
• Burst attenuation/suppression: alternating higher activity with 50–99% attenuation/suppression.
• Suppression/attenuation: >99%; suppressed when all activity <10 µV, attenuated when all activity <20 µV but not suppressed.
• For noncontinuous records report attenuation or suppression percent using record/epoch as denominator.
• Stimulus-induced periods are SI-attenuation or SI-suppression.

Criteria & assessment

• Each pattern lasts >=10 s and the pair alternates spontaneously/regularly for >=6 complete cycles; a cycle includes each state once.
• Describe each pattern and typical duration; note awake/stimulated versus less-awake state when known.
• If each pattern lasts >60 s, state-change criteria are also met.

Criteria & assessment

• An EEG pattern with a definite time-locked clinical correlate, OR EEG AND clinical improvement after parenteral antiseizure medication.
• A definite correlate must accompany the pattern and be absent when that pattern is absent; subtle signs can qualify.
• Duration <10 s qualifies only with a definite clinical correlate. An ECSz need not meet ESz; report both when both qualify.

Criteria & assessment

• ECSz persists >=10 continuous minutes OR occupies >=20% of any 60-minute interval.
• Exception: ongoing bilateral tonic-clonic motor seizure qualifies at >=5 continuous minutes.
• Known epileptic encephalopathy additionally requires increased prominence/frequency of discharges from baseline with clinical deterioration, OR EEG and clinical improvement following parenteral antiseizure medication.

Criteria & assessment

• Either discharges averaging >2.5 Hz for >=10 s (>25 discharges/10 s), OR a pattern with definite evolution lasting >=10 s.
• Sharply contoured discharges >200 ms may qualify through the high-rate pathway even when not technically epileptiform.
• Evolution must satisfy the source RPP evolution criteria; amplitude change alone is insufficient.

Criteria & assessment

• Qualifying ESz continues for >=10 minutes, OR total ESz duration is >=20% of any 60-minute interval.
• Hourly burden uses the specified 60-minute denominator, not a cropped display's duration.

Criteria & assessment

• Always exclude ESz/ESE.
• Pathway A: PD/SW averages >1 and <=2.5 Hz over 10 s.
• Pathway B: PD/SW averages >=0.5 and <=1 Hz over 10 s AND (has a plus modifier OR fluctuation).
• Pathway C: lateralized RDA averages >1 Hz for >=10 s AND (has a plus modifier OR fluctuation); includes LRDA, BIRDA, UIRDA and MfRDA.
• IIC describes an electrographic category, not a diagnosis or an automatic treatment order.

Criteria & assessment

allowed values

G

name

Generalized

rule

Bilaterally synchronous and symmetric, including a restricted field. Bilateral asymmetry or asynchrony that shifts and is not consistently lateralized to one side more than 80% of the time remains G.

qualifiers

predominance

frontally

anterior voltage at least 50% greater than posterior

occipitally

posterior voltage at least 50% greater than anterior

midline

midline voltage at least 50% greater than parasagittal

not otherwise specified

similar voltage in all regions and none of the preceding

asynchrony

For shifting asynchrony, record typical inter-side lag.

L

name

Lateralized

rule

Unilateral; or bilateral with clearly and consistently greater amplitude on one side; or bilateral with a consistent lead-in from one side. Includes focal, regional, and hemispheric patterns.

qualifiers

laterality

Specify side.

extent

• unilateral
• bilateral asymmetric
• bilateral asynchronous
• both asymmetric and asynchronous

consistency

Bilateral asymmetric and bilateral asynchronous examples require the same side more than 80% of the time.

lag

For bilateral asynchronous, record typical inter-side lag.

lobes

• F
• P
• T
• O
• hemispheric if no finer localization

BI

name

Bilateral independent

rule

Two independent, therefore asynchronous, lateralized patterns, one in each hemisphere, occurring simultaneously (overlapping in time), not sequentially.

qualifiers

symmetry

• symmetric
• asymmetric with L > R or R > L

lobes

• F
• P
• T
• O
• hemispheric

UI

name

Unilateral independent

rule

Two independent, therefore asynchronous, periodic or rhythmic patterns in the same hemisphere occurring simultaneously, not sequentially. A focal midline pattern can be ipsilateral to an independent left or right pattern.

qualifiers

per pattern

• unilateral/bilateral extent
• asymmetry/asynchrony if bilateral
• side
• most involved lobe(s)

Mf

name

Multifocal

rule

At least three independent lateralized patterns, with at least one in each hemisphere, all occurring simultaneously.

qualifiers

symmetry

• symmetric
• asymmetric with L > R or R > L

lobes

• F
• P
• T
• O
• hemispheric

Criteria & assessment

PDs

name

Periodic discharges

rule

Relatively uniform waveform morphology and duration, a discernible inter-discharge interval, and recurrence at nearly regular intervals.

regularity

Cycle length varies by less than 50% from one cycle to the next in a majority (>50%) of cycle pairs.

discharge

Waveform shorter than 0.5 s irrespective of phases, or at least 0.5 s with no more than 3 phases; must stand out from background.

RDA

name

Rhythmic delta activity

rule

Relatively uniform waveform morphology and duration with no interval between waves; irregular or polymorphic delta is not RDA.

regularity

Period varies by less than 50% from the subsequent cycle in a majority (>50%) of cycle pairs.

frequency hz

min

0.5

max

4

note

Sharp crests or troughs do not prevent a pattern from being rhythmic.

SW

name

Spike-and-wave or sharp-and-wave

rule

Spike, polyspike, or sharp wave consistently followed by a slow wave in a regular alternating repeating pattern, with a consistent component relationship for at least 6 consecutive cycles and no interval between complexes.

Criteria & assessment

• Review/report first 30–60 minutes promptly.
• Written report at least once per 24 hours; significant intervening changes get separate epochs/reports.
• Communication updates at least twice daily recommended except unusually stable circumstances.

Criteria & assessment

onset

sudden

Absent to well-developed within 3 s.

gradual

Does not meet sudden-onset definition.

triphasic morphology

Three negative-positive-negative phases, each longer than the preceding and the positive phase of highest voltage; or positive-negative biphasic appearance when a low-voltage first negative phase is obscured by background. PDs and SW only.

anterior posterior lag

Consistent measurable delay >100 ms from most anterior to most posterior derivation, or reverse; report typical anterior-to-posterior delay in ms (negative for posterior-to-anterior) in longitudinal bipolar and referential montage, preferably ipsilateral-ear reference. PDs or spike/sharp component of SW only.

polarity

values

• positive
• negative
• dipole, tangential
• unclear

rule

Describe dominant/highest-voltage phase in a referential montage; PDs or spike/sharp component of SW only.

Criteria & assessment

• No prominent motor activity; applies to electrographic or electroclinical seizure/status.
• Prefer nonconvulsive to subclinical: absence of prominent movement does not establish absence of clinical contribution.

Criteria & assessment

• Daily burden: total pattern or seizure duration per 24 hours; hourly and maximal hourly burdens also reportable.
• Daily pattern index: daily burden multiplied by mean frequency; retain units (Hz-hours or Hz-minutes).

Criteria & assessment

phases

formula

1 + number of baseline crossings of the typical discharge

montage

longitudinal bipolar, channel where most apparent

baseline rule

Start and end points are not crossings

bins

• 1
• 2
• 3
• >3

sharpness

spiky

component duration at EEG baseline <70 ms

sharp

70-200 ms

sharply contoured

steep slope on one side and/or pointed/apiculate inflection, but too long to be sharp

blunt

smooth or sinusoidal

required

Describe dominant (highest-voltage) phase and sharpest phase if different.

absolute voltage peak to trough uV

montage

standard longitudinal bipolar 10-20, channel where pattern is most apparent

PD measurement

highest-voltage component

SW measurement

spike/sharp component

bins

very low

<20

low

20-49

medium

50-149

high

>=150

relative voltage PDs only

Ratio of the highest-voltage component of the typical discharge to typical between-discharge background in the same channel and montage; bin as <=2 or >2.

Criteria & assessment

subtypes

+F

Superimposed theta-or-faster activity, rhythmic or not, on PDs or RDA. It must be part of the pattern, not merely background; for PDs it may be continuous if absent when PDs are absent, or occur regularly with each discharge.

+R

Superimposed rhythmic or quasi-rhythmic delta activity; PDs only.

+S

Associated sharp waves, spikes, or sharp contour; RDA only; present at least once per 10 s and not an SW pattern.

combinations

• PDs+FR
• RDA+FS

bilateral rule

If a bilateral pattern qualifies for plus on only one side, the overall main term still receives the plus modifier.

EDB

definite

Abundant or continuous RDA+F with fast activity stereotypically related to the delta wave, or abundant/continuous PDs+F where each PD is a single blunt delta wave and fast activity is stereotypically related to that delta wave.

possible

Meets either EDB form but is only occasional/frequent, or the fast activity lacks a stereotyped delta-wave relationship.

not EDB

RDA+F/PDs+F lacking both required EDB conditions; a periodic pattern can be EDB only if PDs are blunt delta brushes; fast activity between delta waves or present as background does not qualify.

Criteria & assessment

• An IIC RPP persists >=10 continuous minutes OR >=20% of any 60-minute interval.
• Parenteral antiseizure medication improves the EEG without clinical improvement.
• All duration, IIC and response requirements are conjunctive.

Criteria & assessment

• Present requires attenuation with eye opening.
• Wait >1 s after eye closure before measuring frequency; report to nearest 0.5 Hz.

Criteria & assessment

• Categories: beta >13 Hz, alpha, theta, delta.
• Report all 2 or 3 bands when equally prominent.

Criteria & assessment

prevalence percent record or epoch

continuous

>=90

abundant

50-89

frequent

10-49

occasional

1-9

rare

<1

denominator

proportion of the record or epoch that includes or is within the pattern; intervals between widely spaced PDs count as pattern duration

multiple patterns

Record each pattern and its own prevalence.

typical duration

very long

>=1 h

long

10-59 min

intermediate

1-9.9 min

brief

10-59 s

very brief

<10 s

also required

longest continuous duration

frequency hz

required

• typical
• minimum
• maximum

categories

• <0.5
• 0.5
• 1
• 1.5
• 2
• 2.5

very brief additional categories

• 3
• 3.5
• 4

PD SW restriction

Typical frequency >2.5 Hz is an RPP only when duration is <10 s; at >=10 s it is outside this RPP contract.

Criteria & assessment

required components

• one main_term_1 localization
• one main_term_2 pattern type

minimum run

consecutive cycles min

6

examples

• 1 Hz for 6 s
• 3 Hz for 2 s

frequency boundary

No RPP may have a typical frequency above 4 Hz. A pattern above 4 Hz lasting at least 0.5 s is outside this RPP contract; one shorter than 0.5 s is not an RPP.

evolution boundary

Within RPP terminology, evolution is limited to patterns at or below 4 Hz and shorter than 10 s. Longer evolving patterns and faster short patterns are delegated to the seizure/BIRD contracts.

Criteria & assessment

• Spike: pointed transient distinct from background, duration >=20 ms and <70 ms at EEG baseline.
• Sharp wave: same definition, duration >=70 ms and <=200 ms (source states 70–200 ms).
• Polyspike: >=2 consecutive spikes with no interdischarge interval, total duration <0.5 s.
• Typical, not required: diphasic/triphasic, apiculate, asymmetric slope, followed by slow wave or other background disruption.

Criteria & assessment

• Abundant: >=1/10 s, but not periodic.
• Frequent: >=1/min and <1/10 s.
• Occasional: >=1/h and <1/min.
• Rare: <1/h.
• When abundant, mean and maximum count per 10-s epoch may be recorded.

Criteria & assessment

• Present requires >=2 background types, each sustained >=60 s.
• Stimulation should transition less-alert to more-alert/stimulated; spontaneous transitions qualify; the more-alert state is primary.
• State changes virtually always imply reactivity; reactivity need not imply a state change when it lasts <60 s.
• Categories: present with normal N2 transients; present with abnormal N2 transients; present without N2 transients; absent.
• Describe K-complexes and spindles separately: present-normal, present-abnormal with abnormality, or absent.

Criteria & assessment

stimulus state

SI

Reproducibly brought about or exacerbated by alerting stimulus in a less-stimulated state, with or without clinical alerting; may also occur spontaneously.

ST

Reproducibly terminated or attenuated by alerting stimulus in a less-stimulated state, with or without clinical alerting; may also self-terminate.

spontaneous

Never clearly induced, exacerbated, improved, or terminated by stimulation.

unknown

Unclear or untested.

stimulus type required

• auditory
• light tactile
• patient care/other nonnoxious
• noxious

evolving

minimum

At least 2 unequivocal sequential changes in the same category.

frequency

Two consecutive changes in one direction, each at least 0.5 Hz; each frequency persists at least 3 cycles.

morphology

Two consecutive novel morphologies; each morphology, including transition forms, persists at least 3 cycles.

location

Sequential spread into or out of at least 2 standard 10-20 electrode locations; involvement of each additional electrode persists at least 3 cycles.

interstep gap

Reach criteria without the changing feature remaining unchanged for 5 or more continuous minutes.

amplitude

Voltage/amplitude change alone is neither evolution nor a new morphology.

fluctuating

minimum

At least 3 changes, no more than 1 minute apart, not qualifying as evolution.

frequency

Each change at least 0.5 Hz; each frequency persists at least 3 cycles.

morphology

Each morphology persists at least 3 cycles.

location

Each change at least 1 standard interelectrode distance; each location persists at least 3 cycles.

amplitude

Voltage/amplitude change alone is not fluctuation.

static

Neither evolving nor fluctuating.

additional reporting

If evolving or fluctuating in frequency, specify minimum and maximum frequency. For nongeneralized patterns specify spread as none, unilateral, or bilateral.

Criteria & assessment

• Alerting stimulus reproducibly induces or exacerbates the qualifying phenomenon; prepend SI to the qualifying term.