What commonly causes focal intermittent rhythmic delta activity (FIRDA)?

Focal intermittent rhythmic delta activity (FIRDA) is often associated with specific pathological conditions, and one of the most common causes is increased intracranial pressure. When intracranial pressure rises, it can lead to disturbances in cerebral circulation and neuronal function, which can manifest as abnormal EEG patterns including FIRDA. This specific waveform typically indicates localized disease or irritability within the brain and may suggest conditions such as brain tumors, hemorrhages, or other mass effects.

In contrast, while normal aging can lead to changes in the EEG, FIRDA is not commonly attributed to aging itself. The deep sleep phase is characterized by different types of brain wave patterns, predominantly slow wave activity, but not specifically FIRDA. Electrical stimulation may produce various EEG changes, but FIRDA is typically not a direct result of this activity. Therefore, the association of FIRDA with increased intracranial pressure highlights its significance as an indicator of underlying cerebral pathology.