What are the EEG changes characteristic of extratemporal poorly localized epilepsy?

Updated: Oct 01, 2020
  • Author: Raj D Sheth, MD; Chief Editor: Selim R Benbadis, MD  more...
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Answer

Answer

Parietal lobe seizures are an example of extratemporal poorly localized epilepsy.

Interictal EEG may be normal or may have spikes or sharp waves in areas outside of the parietal lobe or distant from ictal onset, which may be misleading (see images below).

Electroencephalogram demonstrating interictal patt Electroencephalogram demonstrating interictal pattern of extratemporal spikes (left hemispheric spike and wave).
Electroencephalogram demonstrating interictal patt Electroencephalogram demonstrating interictal pattern of extratemporal spikes (right posterior spikes, temporoparietal).
Electroencephalogram demonstrating interictal patt Electroencephalogram demonstrating interictal pattern of extratemporal spikes (left posterior spikes, temporoparietal).
Electroencephalogram demonstrating repetitive cent Electroencephalogram demonstrating repetitive central spikes (maximal Cz).
Electroencephalogram demonstrating repetitive cent Electroencephalogram demonstrating repetitive central sharp waves (maximal Cz).
Electroencephalogram demonstrating repetitive left Electroencephalogram demonstrating repetitive left frontocentral sharp waves (maximal Cz).

In extratemporal seizures, such as parietal lobe seizures, even the ictal EEG may be normal given seizures are often focal aware. In cases of abnormal EEG, this is more common if motor symptoms are present, as opposed to sensory symptoms alone (see image below of a focal tonic seizure).

Electroencephalogram demonstrating a left fronto-c Electroencephalogram demonstrating a left fronto-central seizure (beginning); rhythmic 14-16 Hz activity (maximal Cz and C3).

 

Electroencephalogram demonstrating a left fronto-c Electroencephalogram demonstrating a left fronto-central seizure (end); evolution to rhythmic 11-12 Hz activity with slightly higher amplitude with abrupt cessation.

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