Multiple subpial transections and magnetic resonance imaging

Abstract Introduction Multiple subpial transection (MST) has been applied to the treatment of refractory epilepsy when epileptogenic zone involves eloquent areas since 1989. However, there is a lack of data evaluating the effect of this surgical technique on the cortex as measured by Magnetic Resonance Imaging (MRI). Patients and methods Ten consecutive patients (3F/7 M, average age: 18.5 years) were operated on using radiating MST (average: 39; min: 19, max: 61) alone ( n  = 3) or associated with another technique ( n  = 7). Seven patients underwent a post-operative 3.0 T MRI while 3 had a 1.5 T MRI. Three patients had an early post-operative MRI and 7 a late MRI, among which 3 previously had an intraoperative MRI. Results The MR sequences that allowed the best assessment of MST-induced changes were T2 and T2*. The traces of MST are more visible on late MRI. These discrete non-complicated stigmas of MST were observed in all 10 studied patients: on the intraoperative MRI they are seen as micro-hemorrhagic spots (hypo-T2), on the early postoperative MRI as a discreet and limited cortical edema whether associated or not with micro-hemorrhagic spots and on the late MRI as liquid micro-cavities (hyper-T2) surrounded with a fine border of hemosiderin. Conclusions MST-induced cerebral lesions are best visualized in T2-sequences, mainly on the late postoperatively MRIs. On all the MRI examinations in this study, the MST are only associated with limited modifications of the treated cortical regions.