What would you expect to see on the EEG of a 60-year-old male with new onset dementia and myoclonus?

In a 60-year-old male presenting with new onset dementia and myoclonus, the presence of generalized periodic epileptiform discharges (GPEDs) on the EEG is a significant finding. GPEDs are typically associated with various forms of metabolic and degenerative encephalopathies, particularly in older patients. Dementia combined with myoclonus may suggest a condition such as Creutzfeldt-Jakob disease or encephalopathy, which often displays GPEDs on EEG.

These discharges are characterized by their recurring, rhythmic nature, usually occurring at a frequency of 1 to 2 Hz, and they can indicate seizures that are not always clinically apparent. The appearance of GPEDs in this clinical context can assist in diagnosing underlying neurodegenerative diseases that may manifest with both cognitive decline (dementia) and movement disorders (myoclonus).

Other patterns typically seen on EEG in different conditions would not be expected here. For instance, generalized tonic-clonic discharges are associated with generalized seizures but are not a typical finding in dementia cases with myoclonus. Localized spikes could point to focal brain lesions or seizure disorders but not particularly to a diffuse process associated with dementia. Lastly, a normal wave