GRDA (formerly FIRDA) on EEG

What it looks like

Runs of monomorphic, bilaterally synchronous delta, often frontally predominant in adults. The older name was frontal intermittent rhythmic delta activity (FIRDA). ¹

What it means at the bedside

A non-specific marker of diffuse encephalopathy: metabolic, toxic, raised intracranial pressure, deep midline lesions. In a large critical-care cohort, GRDA was not associated with seizures, unlike lateralized rhythmic delta (LRDA). ²⁵