Early Onset Epilepsy Caused by Low-Grade Epilepsy-Associated Tumors and Focal Meningeal Involvement

Abstract

Background: Low-grade epilepsy-associated neuroepithelial tumors (LEATs) are a frequent etiology in pediatric patients with epilepsy undergoing surgery. Objective: To identify differences in clinical and post-surgical follow-up between patients with focal meningeal involvement (MI) and those without MI within our cohort of pediatric patients with LEATs. Methods: We retrospectively reviewed all pediatric patients (<18 y) who underwent epilepsy surgery between 2011 and 2017 at our hospital. Cohort inclusion required histological diagnosis of LEATs and post-surgical follow-up of ≥2 y. We subsequently stratified patients according to presence of neuroradiological MI. Results: We identified 37 patients: five with MI and 32 without. Half of patients (19) were drug sensitive at surgery; similar between groups. The group with MI differed mainly for age of epilepsy-onset (0.6 vs. 7.0 y) but not for epilepsy duration (0.9 vs. 1.5 y). Post-surgery radiological follow-up (median 4.0 y; IQR 2.8-5.0 y) did not indicate disease progression. Seizure outcome was excellent in both groups, with 34 patients overall being both drug- and seizure-free. Conclusions: Our study identified a new subgroup of LEATs with focal MI and excellent post-surgical outcome. Moreover, this highlights the effectiveness of early surgery in pediatric LEATs.

Keywords: drug resistant epilepsy; epilepsy; meningeal neoplasms; neuroepithelial tumors; pediatrics; surgery; temporal lobe.

Figure 1

Flowchart illustrating patient selection.

Figure 2

MRI of five patients belonging to Group 1 (age at epilepsy onset <3 y and evidence of meningeal enhancement). All five cases demonstrate clear mesial temporal localization with an enhancement after gadolinium injection along the meningeal layer. (a) Patient #1. One-year old girl with a left mesial temporal lobe lesion with nodular parenchymal and meningeal enhancement (arrow). (b) Patient #2. One-year, 11-month old boy with a right mesial temporal lobe lesion demonstrating meningeal enhancement along the mesial margins (arrow). (c) Patient #3. Ten-month old boy with a left mesial temporal lobe lesion showing anterior nodular parenchymal enhancement with associated meningeal enhancement and thickening (arrow). (d) Patient #4. Three-year, 9-month old girl with a left temporal lobe lesion associated with a small nodular parenchymal enhancement and anterior meningeal enhancement (arrow). (e) Patient #5. Two-year old boy with a left mesial temporal lesion with partial nodular and meningeal enhancement along the anterior and mesial margins (arrow). MRI, magnetic resonance imaging.

Figure 3

Histopathological findings in patients with LEATs and MI. (A) Low-grade tumor with calcification (HE stain, 20×). (B) Meningeal infiltration and thickening. We can recognize the nearby cortex in the right inferior quadrant (see arrow) (HE, 20×). (C) Evident on the left side is the cortex infiltrated by the tumor and over the center and right side is evidence of MI (synaptophysin). LEATs, low-grade epilepsy-associated neuroepithelial tumors; MI, meningeal involvement.

Figure 4

Age at epilepsy onset and duration of epilepsy for the MI (n = 5) and no-MI (n =3.2) groups. A clear difference in age at epilepsy onset (years) is evident, while duration of epilepsy (years) is similar. Values are median (line), interquartile range (box), and range (bars). MI, meningeal involvement.