← Critical-care EEG
Main term 1: localization
Main term 1 specifies the spatial organization of the RPP.
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
Source · 2021ACNS critical-care EEG terminology · PDF p. 9 ↗
Lateralized periodic discharges · PDF p. 9 ↗Bilateral independent periodic discharges · PDF p. 10 ↗Generation & measurement notes
- Store the main term and qualifiers independently; do not infer localization from a single channel label.
Editorial draft · clinical review pending