MRI morphological and volumetric study of the cingulate gyrus and its relevance in partial epileptic patients

The cingulate gyrus (CG) is often involved during partial epileptic seizures. The purpose of the study was to analyse the CG morphology and to measure the CG volume in epileptic patients, in order to detect subtle MRI abnormalities such as atrophy, which could be indicative of its implication in the epileptogenic area. The population consisted of 20 epileptic patients (31.2 +/- 9.4 years) and 20 normal volunteers (31.8 +/- 7.7 years). The epileptic patients underwent intracerebral recordings, and were sub-divided into five patients presenting with seizures involving the CG (CG 1), seven patients in whom the CG was only secondarily involved (CG 2) and eight patients in whom the CG was not invoved at all (CG 3). All subjects were investigated by MRI (1.5 tesla Gyroscan Philips): axial T1w 3D Gradient Echo acquisitions, thickness 1.5 mm, reconstructions in all planes. At first, we described the sulcal limits of the CG, trying to define a "normalised CG". In a second step, we segmented the CG intrasulcal grey matter using the "Surgiscope Scopeplan" (Elekta). We compared (Mann and Whitney U test [alpha=0.05]), the CG volumes of CG 1 to CG 2 + 3, and the volume of CG 1 and of CG 1 + 2 + 3 to that of normal volunteers. There was no significant difference between CG 1 and CG 2 + 3 (P= 0.89), between CG 1 and normal volunteers (P= 0.75) or between CG1 + 2 + 3 and normal volunteers (P = 0.83). The volumetric analysis showed no atrophy of the CG in epileptic patients and did not distinguish the group in whom seizures involved the CG, from the other groups.