FIRDA (frontal intermittent rhythmic delta activity)
- Intermittent: In cycles, so not continuous
- Rhythmic: Repetition of a waveform with relatively uniform morphology and duration, without an interval between consecutive waveforms.
- Delta: Delta waves
- The FIRDA can be more specified with the prevalence, duration, frequency, amplitude, stimulus-induced (SI), Evolving OR Fluctuating (both terms refer to changes in either frequency, location or morphology).
- If a more ictal appearance it can be categorized as FIRDA+:
- +F: superimposed fast activity.
- +S: superimposed sharp waves or spikes, or sharply contoured.
- +FS: superimposed fast activity and sharp waves or spikes, or sharply contoured.
- Often due to global cerebral dysfunction (e.g. metabolic-, toxic- encephalopathy, traumatic)
- FIRDA is rarely due to a subcortical dysfunction/lesion (e.g. lewy body dementia) or elevated intracranial pressure.
- A small amount of FIRDA, especially when it is restricted to drowsiness, can be a normal in elderly or children.
FIRDA in a 70 year old male (source)
- ACNS STANDARDIZED ICU EEG NOMENCLATURE v. 2012