Role of magnetoencephalography in predicting the epileptogenic zone and post-operative seizure outcome - A retrospective study.

PURPOSE: Study assessed the role of MSI in predicting the post-operative seizure outcome. METHODS: This retrospective study included patients who underwent MEG and epilepsy surgery and had a minimum 6 months of postoperative follow-up. Concordance of MEG cluster with post-surgical resection cavity was classified as follows Class I) Concordant and region-specific, Class II) Concordant and region non-specific, Class III) Concordant lateralization only and Class IV) Discordant lateralization. The relationship between MSI concordance and post-operative seizure outcome was assessed. RESULTS: A total of 183 patients (M: F = 109:74) were included. The mean age at onset of seizures: 8.0 ± 6.4 years. The dipoles were frequent in 123(67.2 %). The primary cluster orientation was regular in 59 (32.2 %) and mixed in 124 (67.8 %) patients. Concordance between MEG and resection cavity: Class I - 124 (67.8 %), class II- 30 (16.4 %), class III- 23 (12.6 %), and class IV- 6 (3.3 %). The post-surgically mean duration of follow-up was 19.52 ± 11.27 months. At 6-month follow-up period, 144 (78.7 %) patients had complete seizure freedom out of which 106 (73.6 %) had class I concordance. Concordance of MEG with resection cavity was associated with a good outcome at 6 months (p = 0.001), 1 year (p = 0.001), 2 years (p = 0.0005) and 5 years (p = 0.04). MEG cluster characteristics had no association with seizure outcome except the strength of the cluster and outcome at 3 years (p = 0.02) follow-up. CONCLUSION: The study supports that the complete resection of the MEG cluster had high chance of seizure-freedom and can be used as a complementary noninvasive presurgical evaluation tool.

Sub-lobar dysplasia - A comprehensive evaluation with neuroimaging, magnetoencephalography and histopathology.

Sublobar dysplasia, a rare cortical malformation has been defined in only 8 patients to date. It was identified on the basis of histopathological features and MRI findings. We report a right temporal sublobar dysplasia, with detailed evaluation including neuroimaging, magnetoencephalography and histopathology to further characterize the pathology. Additional pathological features included a deep collateral sulcus in the basal right temporal lobe, thinned out right corticospinal tract, and bilateral asymmetric basal ganglia changes. Magnetoencephalograpy localized the seizure focus to the posterior margin of the dysplasia. Histopathological evaluation helped exclude other types of dysplasia. Similar to a previous study, the child had Engel 1a outcome.