Abstracts

Rationale: Meningioangiomatosis (MA) is a rarely encountered neoplasm which may be a surgically amenable cause for epilepsy. MA occurring concurrently with focal cortical dysplasia (FCD) is infrequently described in the literature, which may have implications in regards to extralesional epileptogenicity and poor response to surgical lesionectomy. A staged surgical approach of intracranial implantation may offer a greater opportunity to adequately localize the epileptogenic zone and extend resection margins with preservation of functional tissue. Methods: A 30 year old female with MA and FCD presented preoperatively with medically intractable epilepsy since the age of 12 and events described as weekly clusters of brief confusional spells associated with hypermotor activity. Radiographic, electrographic, histopathological findings are reviewed in the context of a meta-analysis of the literature. A staged surgical approach with an initial implantation of subdural electrodes to verify lateralization and localization, followed by a larger grid implantation after partial excision of the lesion in order to expand the margins of resection and to allow for functional mapping was performed. Results: Scalp EEG was remarkable for paroxysmal generalized polyspike discharges, with evolution of non-lateralized frontally predominant generalized fast frequency activity at seizure onset. MRI demonstrated an abnormal frontal gyral pattern, with a calvarial defect and tiny focus of enhancement. PET showed metabolic reductions in the inferobasal temporal lobes and left anterior frontal lobe. The first stage of intracranial monitoring revealed seizures with initial electrographic change over the left frontal region perilesionally with rapid bisynchrony and spread to the left temporal region. Interictal spike wave discharges were observed independently in the left frontal, left temporal, and right frontal lobes. After initial resection of the lesion, subsequent grid implantation and mapping redemonstrated seizure onset from the surrounding tissues, in close approximation to the left frontal language area and motor cortex. Histopathology from the initial resection showed intracortical plaque-like proliferation of meningothelial cells, microvasculature and fibroblast-like cells consistent with MA. Subsequent resection showed pyramidal neurons with apical dendrites oriented in directions other than the pial surface disrupting normal lamination consistent with FCD type IIa. Outcome is Engle class II with 4 seizures at 1 year and substantial functional improvement. Conclusions: The literature describes variable outcome with local surgical excision with rates of seizure freedom between 43-68%. MA is rarely reported in association with FCD, however extra-lesional and multifocal or generalized electrographic findings have been described. A staged surgical approach with functional mapping may allow for more complete resection of the epileptogenic zone with a lower risk for functional impairment, and should be considered when MA is thought to be the cause of medically refractory epilepsy.