Which neonatal EEG patterns are characteristic of severe abnormalities?

Updated: Oct 03, 2019
  • Author: Rosalia C Silvestri-Hobson, MD; Chief Editor: Selim R Benbadis, MD  more...
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With regard to severity and prognosis, severe and irreversible abnormalities should be distinguished from moderate, reversible abnormalities. Severe abnormalities correspond to 2 main EEG patterns, inactive and paroxysmal, both of which are accompanied by a lack of sleep cycles and a lack of reactivity to internal or environmental stimuli.

The inactive or isoelectric pattern consists of cerebral activity below 10 mV that is continuously present throughout the record. Brief intervals of low-voltage activity, which are located over the posterior head regions, may occasionally be present. This pattern may occur in varying clinical conditions and often occurs with the following states:

  • Early severe asphyxia or massive hemorrhage

  • Severe inborn metabolic deficits

  • CNS bacterial or viral infections

  • Gross congenital malformations (see image below)

    Inactive or isoelectric pattern. Inactive or isoelectric pattern.
  • Drug-induced state

  • Hypothermia

  • Postictal recording

In the absence of a drug-induced state, hypothermia, or postictal recording, the prognosis is poor but not necessarily fatal.

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