Co-occurring Patterns of Periodic Epileptiform Discharges

Periodic Epileptiform Discharges (PEDs) can occur alongside various other EEG patterns, reflecting different underlying neurological conditions and brain states. 

Co-occurring Patterns of Periodic Epileptiform Discharges (PEDs):

1.      Bilateral Periodic Epileptiform Discharges (BiPEDs):

§  BiPEDs are a specific type of PEDs that occur symmetrically and synchronously across both hemispheres. They are often maximal in the midfrontal region and can be associated with conditions such as subacute sclerosing panencephalitis (SSPE).

2.     Triphasic Waves:

§  While PEDs are characterized by their triphasic waveform, they can also co-occur with other triphasic patterns. However, the distinguishing feature is that PEDs are periodic, whereas triphasic waves may not have a consistent interval. Triphasic waves are often associated with metabolic disturbances and can appear in conditions like hepatic encephalopathy.

3.     Frontal Intermittent Rhythmic Delta Activity (FIRDA):

§  FIRDA is another EEG pattern that can co-occur with PEDs. FIRDA is characterized by rhythmic delta activity in the frontal regions and is often associated with diffuse cerebral dysfunction. The presence of both FIRDA and PEDs may indicate a more severe underlying condition.

4.    Background Activity Changes:

§  The background activity accompanying PEDs is typically disorganized and may show generalized theta or delta frequency range activity. In cases of anoxia, the background may be suppressed or demonstrate electrocerebral inactivity. This disorganized background can coexist with PEDs, reflecting the diffuse cerebral dysfunction .

5.     Myoclonic Activity:

§  In cases where PEDs are associated with SSPE, they are often accompanied by myoclonic jerks. The myoclonic activity may produce movement artifacts that can complicate the interpretation of the EEG but are clinically significant in the context of PEDs.

6.    Other Epileptiform Discharges:

§  PEDs can also coexist with other types of epileptiform discharges, such as Interictal Epileptiform Discharges (IEDs). The presence of both patterns may indicate a more complex seizure disorder or underlying brain pathology.

Summary:

Periodic Epileptiform Discharges (PEDs) can co-occur with various EEG patterns, including Bilateral Periodic Epileptiform Discharges (BiPEDs), triphasic waves, FIRDA, changes in background activity, myoclonic activity, and other epileptiform discharges. The presence of these co-occurring patterns can provide valuable insights into the underlying neurological conditions and help guide clinical management.