← Critical-care EEG
Phases, sharpness, and voltage modifiers
These modifiers describe discharge structure, contour, and amplitude.
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.
Source · 2021ACNS critical-care EEG terminology · PDF p. 13 ↗
Generation & measurement notes
- Retain the acquisition montage with every amplitude, phase, and polarity-related field.
Editorial draft · clinical review pending