engleski

Surgery for focal cortical dysplasias – a single centre experience

Malformations of cortical development are common cause of pharmacoresistant epilepsy. While some large malformations as hemimegalencephaly, shizencephaly, heterotopias are obvious, there are subtle changes in cortical dysplasias that left commonly unrecognized. Some large series of surgically treated patients show that cortical dysplasias are commonly thought as causes of nonlesional epilepsy, because being unvisible. Microscopic features show abnormalities in cortical layers and neuronal differentiation. This is different spectrum of subtypes which are classified most commonly according to Palmini and Blümcke ILAE classification. Patients and methods: Aproximately 30% of the patients with medically uncontrollable epilepsy have focal cortical dysplasias visible on conventional MRI scan (3T), there are certain number of patients that only morphometric analysis can delineate dysplasias in previously MRI negative epilepsies. Patients with lesion-free epilepsies are advised to perform morphometric analysis that can delineate unrecognizable FCDs. Morphometric analysis is voxel based postprocessing method based on algorythms of the statistical parametric mapping software (MAP7). Maps that are created are tridimensional highlighted areas of the brain with blurred gray- white matter junction and abnormal gyration. Results: In the past three years, we have operated 20 patients with clear histology for cortical dysplasias. All our patients were classified according to Blümcke: ILAE classification system into type Ilb. Subdural or depth electrodes were implanted for any of the following reasons: 1. To confirm the ictal onset zone, and 2. To perform functional mapping with electrical stimulation of the cortex if the presumed epileptogenic zone was thought to be close to eloquent cortex. In cases with clear dysplasia far from eloquent cortex, neuronavigation was performed and resection of the malformation was performed without intraoperative monitoring. Apart from that group of patients there is other group of patients with MRI proved cortical dysplasias in eloquent brain regions that are operated with VNS implantation. In that group of patients seizure reduction was 51%. Conclusion: Focal cortical dysplasias are common cause of epilepsy but most commonly unrecognized despite excellent surgical result after resection. Outcome could be improved by invasive monitoring and morphometric analysis can delineate cryptogenic lesions in so called lesion-free epilepsies. If there are not in close proximity with eloquent cortex the surgical result is excellent leading in majority of patients with complete seizure freedom. If dysplasias are in the eloquent cortex, VNS can reduce the number of seizures by half.

focal cortical dysplasia ; MAP-07 ; neuronavigation ; invasive monitoring ; surgery

nije evidentirano