Presurgical multimodality neuroimaging in electroencephalographic lateralized temporal lobe epilepsy

Area of Science:

• Neuroimaging
• Epilepsy Research
• Medical Diagnostics

Background:

• Nonlesional unilateral temporal lobe epilepsy (TLE) presents diagnostic challenges for presurgical lateralization.
• Electroencephalogram (EEG) defines unilateral TLE, but neuroimaging is crucial for surgical planning.
• Multiple advanced neuroimaging techniques exist, each with varying diagnostic capabilities.

Purpose of the Study:

• To compare the efficacy of 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET), hippocampal volumetry (HV), T2 relaxometry, and proton magnetic resonance spectroscopic imaging (1H-MRSI) for presurgical lateralization in nonlesional unilateral TLE.
• To assess the predictive value of these imaging modalities for postoperative seizure-free outcomes.

Main Methods:

• Prospective study of 25 patients with EEG-defined unilateral TLE and age-matched controls.
• Comparison of FDG-PET, HV, and 1H-MRSI in 23 patients; T2 relaxometry in 13 patients.
• Analysis of lateralization accuracy and correlation with postoperative seizure outcomes.

Main Results:

• FDG-PET achieved the highest lateralization rate (87%), followed by HV (65%) and 1H-MRSI measures (NAA/(Cho + Cr) 61%, NAA 57%).
• In patients with normal MRI, FDG-PET and 1H-MRSI showed higher lateralization rates than HV.
• Only hippocampal atrophy demonstrated a significant correlation with postoperative seizure-free outcome.

Conclusions:

• FDG-PET is the most sensitive neuroimaging method for lateralizing EEG-defined TLE.
• Both FDG-PET and 1H-MRSI can lateralize TLE in patients with normal MRI, but only hippocampal atrophy predicts successful surgical outcomes.
• Bilateral abnormalities on MRI or 1H-MRSI do not preclude favorable surgical results.