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Single photon emission computed tomography-EEG relations in temporal lobe epilepsy
1Department of Neurology, Yonsei University College of Medicine, Seoul, Korea.
Neurology
|October 27, 1997
Summary
Single photon emission computed tomography (SPECT) shows limited reliability for confirming epilepsy source in presurgical evaluations. Ictal SPECT accuracy depends heavily on electroencephalogram (EEG) patterns, especially in bitemporal epilepsy cases.
Area of Science:
- Neurology
- Neurosurgery
- Medical Imaging
Background:
- Medically intractable temporal lobe epilepsy (TLE) necessitates accurate presurgical evaluation.
- Single photon emission computed tomography (SPECT) is used in presurgical evaluation, but its independent confirmatory role requires critical investigation.
- Spreading ictal discharges can affect remote cerebral blood flow, potentially impacting SPECT interpretation.
Purpose of the Study:
- To critically investigate the role of ictal SPECT as an independent confirmation test in the presurgical evaluation of TLE.
- To analyze the relationship between peri-injection electroencephalogram (EEG) patterns and ictal SPECT findings.
- To evaluate the concordance of SPECT and EEG lateralizations with the epileptogenic temporal lobe.
Main Methods:
- Retrospective review of interictal and ictal EEG and SPECT in 19 TLE patients with successful surgical outcomes.
- Classification of patients into unitemporal and bitemporal groups based on interictal epileptiform discharges (IED).
- Analysis of ictal EEG features (lateralized vs. non-lateralized) and their correlation with SPECT lateralization.
Main Results:
- Interictal SPECT correctly lateralized in 8/9 unitemporal IED cases but only 5/10 bitemporal IED cases.
- Ictal SPECT showed high concordance with peri-injection EEG but correctly lateralized the epileptogenic region in only 11/19 patients.
- Ictal SPECT accuracy was highest when pre- and post-injection EEG epochs showed ipsilateral lateralization; complex patterns and false lateralizations increased with non-lateralized or discordant EEG.
Conclusions:
- Interictal SPECT is more sensitive and reliable in unitemporal than bitemporal TLE.
- Ictal SPECT's reliability is closely linked to peri-injection EEG patterns but frequently leads to false lateralization.
- The utility of ictal SPECT as an independent confirmation test in presurgical TLE evaluation warrants reappraisal.