FIRDA
Pronunciation: FUR-dah
Also written as: FIRDA — frontal intermittent rhythmic delta activity
Frontal intermittent rhythmic delta activity, an abnormal EEG pattern suggesting deep midline brain dysfunction.
Full Definition
Frontal intermittent rhythmic delta activity (FIRDA) is an abnormal EEG pattern characterized by bursts of monomorphic 1.5-3 Hz delta waves that appear prominently over the frontal regions. The discharges are typically bilateral, synchronous, and have a rhythmic, regular appearance that distinguishes them from other forms of slow-wave activity. FIRDA suggests dysfunction of deep midline structures such as the thalamus or upper brainstem, and can be associated with various conditions including metabolic encephalopathy, increased intracranial pressure, or deep-seated lesions. Unlike focal slowing, FIRDA appears intermittently and has a characteristic regular morphology that makes it easily recognizable.
Usage
Usage note: Distinguish from OIRDA (occipital intermittent rhythmic delta activity) by location.
In Context
- "Intermittent 2 Hz FIRDA suggested possible thalamic dysfunction in this confused patient." — Encephalopathy evaluation
- "The FIRDA pattern resolved following treatment of the metabolic disturbance." — Follow-up EEG report