What does diffuse slowing on an EEG usually indicate?

Diffuse slowing on an EEG typically signifies generalized slowing due to metabolic conditions. This pattern occurs when there is widespread brain dysfunction affecting the cortex, which can be attributed to various metabolic disturbances such as encephalopathy, hypoxia, or toxic effects. These conditions interfere with the normal electrical activity of the brain, leading to slower waves throughout the recording rather than localized abnormalities.

In cases of diffuse slowing, the slow waves often reflect a global decrease in alertness or cognitive function, which can result from systemic metabolic issues affecting brain function rather than isolated lesions or localized injuries. This understanding highlights the diagnostic significance of diffuse slowing as an indicator needing further investigation into possible underlying metabolic or systemic problems.

Localized brain injury would typically present with focal changes rather than diffuse slowing, while seizure disorders often exhibit sharp waves or spikes rather than generalized slowing. The normal aging process can lead to some slowing, but it usually does not exhibit the widespread and significant changes seen in metabolic conditions.