EEG abnormality occipital intermittent rhythmic delta activity true true Fairly regular or approximately sinusoidal waves, mostly occurring in bursts at 2-3 Hz over the occipital areas of one or both sides of the head. http://www.case.edu/EpSO.owl#OccipitalIntermittentRythmicDeltaActivity Occipital intermittent rhythmic delta activity (OIRDA) is described as an intermittent, sawtooth shaped, unilateral or bilateral, symmetrical, medium or high amplitude, paroxysmal and regular delta frequency activity occurring in the occipital region during electroencephalography (EEG) monitorization https://www.ncbi.nlm.nih.gov/pubmed/12684556