What are the EEG changes characteristic of temporal lobe epilepsy?

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

Answer

Temporal lobe epilepsy (TLE) is the most common focal epilepsy, making up about one third of all epilepsies. TLE can be separated into mesial versus lateral temporal lobe epilepsy. 

Interictally, mesial TLE may have more anterior temporal spikes or sharp waves, whereas lateral TLE may have more mid-temporal or posterior temporal spikes or sharp waves.

Electroencephalogram demonstrating interictal patt Electroencephalogram demonstrating interictal pattern (sharp waves) in left temporal lobe epilepsy.
Electroencephalogram demonstrating interictal patt Electroencephalogram demonstrating interictal pattern of independent left and right temporal sharp waves, which can be seen in temporal lobe epilepsy.

Ictally, mesial TLE may have a rhythmic, crescendo-like theta activity with decreasing frequency and increasing amplitude (see image below of right temporal lobe seizure). Lateral TLE may be similar to mesial TLE or may have a broader distribution and slower frequency (see image below of left temporal lobe seizure).

Electroencephalogram demonstrating a left temporal Electroencephalogram demonstrating a left temporal lobe seizure (beginning) with 2-3 Hz rhythmic delta activity.
Electroencephalogram demonstrating a left temporal Electroencephalogram demonstrating a left temporal lobe seizure (middle), evolving to rhythmic theta activity.
Electroencephalogram demonstrating a left temporal Electroencephalogram demonstrating a left temporal lobe seizure (end), further evolving to diffuse delta activity prior to abrupt cessation.
Electroencephalogram demonstrating right temporal Electroencephalogram demonstrating right temporal lobe seizure (beginning); rhythmic delta activity evolving to rhythmic theta activity over the right temporal region.
Electroencephalogram demonstrating a right tempora Electroencephalogram demonstrating a right temporal lobe seizure (middle); continued right temporal rhythmic theta activity.
Electroencephalogram demonstrating a right tempora Electroencephalogram demonstrating a right temporal lobe seizure (end), resolution of right temporal rhythmic theta.

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