A neurodevelopmental basis for BECTS: evidence from structural MRI

Abstract

Purpose: BECTS (benign epilepsy with centro-temporal spikes) is one of the most common childhood-onset epilepsy syndromes. We investigated quantitative evidence for brain morphological variation associated with BECTS to provide insights into the neuroanatomical basis of this disorder.

Methods: Three independent BECTS groups were imaged at different stages: (a) near onset (n=16, mean age 9.3±1.6 years), (b) ~9 years after onset (n=9, mean age 15.8±2.3 years), and (c) ~15 years after onset (n=10, mean age 22.7±2.7 years). Age-matched controls were imaged with each group. Whole brain T1-weighted MRI was acquired. Voxel-based morphometry (groups a-c) and cortical thickness analyses (groups b and c) were undertaken within each group and for the groups combined. The relationship between cortical morphology and age was investigated.

Key findings: The voxel-based morphometry analysis indicated increased bilateral grey matter volume in the superior frontal gyrus, insula and right inferior frontal gyrus regions in BECTS. The magnitude of the increase lessened with age of the cases. Cortical thickness analysis revealed thicker cortex in BECTS along middle and inferior frontal gyri bilaterally, left insula and bilateral supramarginal gyrus in the 9-year-after-onset group, that normalised with age. The rate of cortical thickness changes with age were greater in BECTS cases than in controls.

Significance: Increased cortical gray matter associated with BECTS was found. The decreasing magnitude of the effect with increasing age parallels the natural history of the disorder. The areas affected are consistent with neurocognitive dysfunction in BECTS.

Figure 1

Regional volume and thickness increases in BECTS. The top row shows volume increases in the BECTS versus control subjects detected using VBM, with MRI data from all three groups combined (relative grey matter volume p < 0.001 significant clusters displayed, change with age in graph). The bottom row shows increased cortical thickness in BECTS versus control subjects imaged ~9 years after onset (group B only, p < 0.05, false discovery rate corrected). The scatterplots show gray matter volume (A) and thickness (B) changes with age in the respective blobs shown on the inflated brains. The magnitude of gray matter volume and thickness differences in BECTS relative to controls lessened with age.