Abstracts

Rationale: With thoughtful patient selection, the majority of children who undergo surgical resection of cortical dysplasia for intractable epilepsy do quite well. A subset, however, continue to have seizures and may be considered for further surgery. For these patients, radiology and pathology findings may offer answers as to why initial surgical efforts failed. Methods: We identified patients from our epilepsy surgery data base who underwent repeat surgery for cortical dysplasia and continued seizures. Patients who underwent palliative procedures (VNS or corpus callosotomy) or resection in a different location were excluded. MRI findings immediately prior to the repeat surgeries were reviewed as well as pathology results from the repeat surgeries. Results: Eight patients were identified who underwent multiple surgeries for intractable epilepsy and cortical dysplasia. In all patients, the initial surgery involved stereotactically guided resection assisted with electrocorticography. In 3 of the patients, repeat MRI showed clearly defined residual dysplasia. These patients were returned to the operative room for further resection. In 3 patients, repeat MRI showed an ill-defined cortical abnormality at the edge of the resection cavity suggestive for residual dysplasia. These patients underwent subdural grid placement for monitoring, followed by further resection. In 2 patients, MRI failed to identify residual cortical dysplasia. One of the 2 underwent grid placement followed by resection. The second underwent a hemispherectomy. In all 8 patients, the pathology from repeat surgery showed further dysplasia with various degrees of inflammatory or post-operative changes. After repeat surgeries, 5 of the 8 patients had a Class I Engel outcome, 1 patient had a Class II outcome, and 2 patients had a Class III outcome.Conclusions: If a patient continues to have seizures after surgery for cortical dysplasia, it may be due to residual dysplasia. This dysplasia may not be clearly defined on MRI. Pathology results confirmed residual cortical dysplasia in all of the cases in this small series independent of MRI findings.