Generalized Periodic Discharges: A Topical Review.

Generalized periodic discharges (GPDs) are generalized discharges that recur with a relatively uniform morphology and duration. They have a quantifiable interdischarge interval. Over the past decade, our understanding of these waveforms has improved considerably. The nomenclature has changed, and etiologic references have been removed. Many disease states can cause GPDs, such as anoxia, toxic/metabolic encephalopathy, infections, nonconvulsive status epilepticus, and hypothermia. Generally, GPDs are morphologically similar regardless of etiology. Generalized periodic discharges that are associated with nonconvulsive status epilepticus are treated with antiseizure drugs, while others are not necessarily aggressively treated. Prognosis for most patients with GPDs is guarded, although this is also dependent on the underlying etiology. As our understanding of GPDs increases, it is also clear that there is much more to be learned about these waveforms.