Quantitative MRI in patients with idiopathic generalized epilepsy. Evidence of widespread cerebral structural changes

Abstract

In patients with idiopathic generalized epilepsy (IGE), visual inspection of routine MRI is normal. However, pathological studies have shown microdysgenesis in grey and white matter in a large percentage of autopsies from cases of IGE. Recently, widespread structural changes not evident on visual inspection of high resolution MRI have been shown using quantitative MRI in patients with apparently focal cerebral dysgenesis. We sought to determine whether similar quantitative changes might be present in patients with IGE, reflecting possible underlying structural abnormalities. Twenty patients with juvenile myoclonic epilepsy, 10 patients each with childhood absence epilepsy and juvenile absence epilepsy, five patients with tonic-clonic seizures on awakening and 30 control subjects had T1-weighted volume acquisition MRI scans on a 1.5T GE scanner. The cerebral hemispheres were segmented semi-automatically, allowing the comparison of normalized cortical and subcortical matter volumes between groups, and investigation of the regional distribution of cortical and subcortical matter in individual subjects. Patients with IGE had significantly larger cortical grey matter volumes than control subjects. Significant abnormalities of the regional distribution of cerebral grey and subcortical matter were found in eight out of 20 patients with juvenile myoclonic epilepsy, one out of 10 patients with childhood absence epilepsy, four out of 10 patients with juvenile absence epilepsy and two out of five patients with tonic-clonic seizures on awakening, but in none of the 30 control subjects. Using MRI-segmentation, we identified widespread cerebral structural changes in patients with various IGE syndromes. Quantitative MRI supports the existence of structural abnormalities in patients with IGE.

Thalamofrontal neurodevelopment in new-onset pediatric idiopathic generalized epilepsy

“…Increased gray matter frontal cortex volume, 21 decreased frontal gray matter, 22 and both regional increased and decreased regional white matter volumes 8 have all been reported. Thalamic findings in IGE include anterior thalamic gray matter volume reductions, 8,21,22 increased anterior thalamic gray matter density, 7,23,24 decreased thalamic volume, 11 and no thalamic volumetric differences. [25][26][27] Although studies reporting thalamic abnormalities conflict, these studies consistently report that differences lie in the anterior and medial thalamus, a region strongly connected to the prefrontal cortex via the anterior thalamic radiation.…”

Effects of very low birthweight on brain structure in adulthood

“…It can therefore include structures that are difficult to quantify using standard landmarks. Similar techniques have shown diffuse abnormalities of brain structure in idiopathic epilepsy (Sisodiya and Free 1997;Woermann et al 1998Woermann et al , 1999, schizophrenia (Hulshoff Pol et al 2001, Sigmundsson et al 2001, and Alzheimer's disease (Baron et al 2001). …”

The Effect of Cognitive Functions on EEG in Patients with Juvenile Myoclonic Epilepsy

“…This may support the studies with neuropsychological tests and advanced structural neuroimaging techniques showing focal cortical abnormalities mainly associated with frontal lobe in patients with JME. [17][18][19][20][21][22][23] Results of ours and similar studies seem to be challenging for further trials designed with tasks more spesific to the critical regions of cortical network.…”