What is the most common etiology associated with LPDs/PLEDs?

The most common etiology associated with lateralized periodic discharges (LPDs) or periodic lateralized epileptiform discharges (PLEDs) is ischemic stroke. These waveforms are often seen in the context of localized brain injury, particularly due to reduced blood flow that results from an ischemic event. When a region of the brain is deprived of oxygen and nutrients, such as during an ischemic stroke, cortical neurons may fire in a correlated manner, resulting in periodic discharges that can be detected on an EEG.

This phenomenon occurs because the area affected by the ischemia may still generate electrical activity despite being compromised. The changes in neuronal excitability and the potential for the development of abnormal rhythmic activity lead to the presence of LPDs or PLEDs in these patients.

Other conditions, such as hemorrhagic stroke, traumatic brain injury, and neurodegenerative disease, can also produce abnormal EEG patterns, but ischemic stroke is more frequently associated with LPDs/PLEDs specifically due to the nature of the injury and the resultant cortical excitability. Thus, when considering the most common etiology, ischemic stroke stands out as the primary cause linked to these EEG findings.