Magnetic source imaging in the preoperative localization diagnosis and prediction of curative effect of focal cortical dysplasia

Abstract

Objective To assess the diagnostic value of magnetic source imaging (MSI) in the preoperative localization of focal cortical dysplasia(FCD). Methods Eighty-two patients with intractable epilepsy resulting from FCD undergone preoperative assessment including MSI, video electroencephalography (VEEG) and electrocorticography (ECoG) from February 2006 to June 2012.The consistency between pre- and intra-surgical assessment was evaluated. For patients who had consistent results, postoperative curative effect was also recorded. The accuracy and predictive values of noninvasive preoperative tests were compared by χ2 test. Results For MSI and ECoG, their results were consistent in 57 cases, partially consistent in 14 cases, and inconsistent in 11 cases. In the postoperative follow-up of 57 patients with consistent results, there were 46 cases with Engel class Ⅰ, 3 cases with Engel class Ⅱ, 4 cases with Engel class Ⅲ, and 4 cases with Engel class IV. For VEEG and ECoG, the results were consistent in 43 cases, partially consistent in 33 cases, inconsistent in 6 cases. The postoperative follow-up showed that 27 cases were graded as Engel class Ⅰ, 5 cases as Engel class Ⅱ, 7 cases as Engel class Ⅲ, and 4 cases as Engel class IV. There were statistically significant differences (χ2=5.023, P=0.025) of the concordance rate with ECoG between MSI(69.51%,57/82)and VEEG(52.44%,43/82). In the postoperative follow-up of patients with consistent results, the curative effect was better in group MSI than in group VEEG (χ2=3.989, P=0.046). Conclusions Preoperativelocalization by MSI shows advantage over VEEG, which meanswhen it achieves an agreement with ECoG, patients with FCD may get better prognosis from the surgical process. Key words: Epilepsy; Magnetic resonance imaging; Cerebral cortex; Nervous system abnormalities