GPD (Generalized periodic discharges)

• Any pattern of generalized synchronous, repetitive discharges of similar morphology
• Relative symmetric
• Periodic, so with interdischarge interval recurring at nearly regular intervals.
  • A pattern can qualify as periodic as long as it continues for at least 6 cycles
• Frontal- or occipital-dominant.
• If a more ictal appearance it can be categorized as GPD+:
  • +F: superimposed fast activity.
  • +R: superimposed rhythmic or quasi-rhythmic activity.
  • +FR: superimposed fast activity and rhythmic or quasi-rhythmic activity.

• Not to be confused with intermittent rhythmic delta activity (IRDA)
  • TIRDA (temporal intermittent rhythmic delta activity
  • OIRDA (occipital intermittent rhythmic delta activity)
  • FIRDA (frontal intermittent rhythmic delta activity

• Not to be confused with lateralized of bilateral independent periodic discharges:
  • LPD (lateralized periodic discharges)
  • BI-LPD (Bilateral independent lateralized periodic discharges)

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GPD’s in a 85 years old male after a out of hospital cardiac arrest (source), the discharges are symmetric, similar morphology with the same interdischarge intervals

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