What is indicated if an EEG shows diffuse slowing?

Diffuse slowing on an EEG suggests widespread impairment in brain function, typically indicating cerebral dysfunction. This pattern can arise from various conditions such as metabolic disturbances, toxic states, generalized seizures, or encephalopathy. It reflects a lack of coordinated electrical activity across the brain, which is not localized to one region, unlike a focus of epileptiform activity or localized injury.

In contrast, local brain injury often presents with focal changes in the EEG, and conditions associated with unresponsive wakefulness would indicate a different set of findings on the EEG. An epileptic focus, while it may lead to slowing in some cases, is characterized by focal spikes or sharp waves rather than diffuse slowing. Thus, recognizing that diffuse slowing corresponds to broader cerebral dysfunction is essential in interpreting EEG findings.