Detecting Subtle Epileptogenic Lesions in MRI-Negative Pediatric Epilepsy

Abstract picture of brain and eeg (electroencaphalogram).
Abstract picture of brain and eeg (electroencaphalogram)
Findings suggest the importance of using MRI postprocessing in the presurgical evaluation process of pediatric patients with epilepsy with apparently normal MRI.

Children with drug-resistant focal epilepsy and focal cortical dysplasia who undergo complete resection of Morphometric Analysis Program (MAP)-positive regions are more likely to experience seizure-free outcomes compared with children who receive no or partial resection, according to a study published in the European Journal of Neurology.

Using a 2002 to 2015 surgical database, researchers included a consecutive cohort of pediatric patients with drug-resistant focal epilepsy and focal cortical dysplasia who underwent epilepsy surgery before ≤21 years of age, had a preoperative 1.5T or 3T MRI, had a negative presurgical MRI, and had ≥12 months of postsurgical follow-up data (n=78).

MAP on T1-weighted volumetric MRI was used to perform MRI postprocessing, and the researchers compared these data with an age-specific normal pediatric population (n=370). Surgical outcome and pathology data were also used to confirm the pertinence of MAP-positive areas.

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Approximately 56% of patients (n=44) demonstrated positive MAP regions. In the 3- to 5-year, 5- to 10-year, 10- to 15-year, and 15- to 21-year-old age groups, the MAP-positive rates were 100% (2 of 2), 77% (13 of 17), 63% (15 of 24), and 40% (14 of 35), respectively. Approximately 45% of patients with temporal resection and 63% of patients with extratemporal resection had MAP-positive rates. Compared with patients with no or partial resection of the MAP-positive regions, patients who received complete resection of MAP-positive regions were more likely to experience a seizure-free outcome (P <.001).

In addition, patients who had no or partial resection of MAP-positive regions experienced worse seizure outcomes compared with MAP-negative patients (P =.002). The extratemporal group was more likely to experience a seizure-free outcome if they had complete resection of the MAP-positive regions (P =.001), whereas the temporal group did not achieve a seizure-free status after complete resection (P =.070).

A limitation of the study includes its retrospective nature, which may have given way to selection bias.

The researchers suggested that the higher MAP-positive rate in the younger age groups emphasizes the importance of voxel-based morphometric MRI postprocessing “for presurgical evaluation for pediatric patients without visually apparent lesions on the MRI.”

Reference

Wang W, Lin Y, Wang S, et al; Pediatric Imaging, Neurocognition and Genetics Study. Voxel-based morphometric MRI postprocessing in nonlesional pediatric epilepsy patients using pediatric normal databases [published online January 27, 2019]. Eur J Neurol. doi: 10.1111/ene.13916