Author(s): Borges, Daniel Filipe ; Leal, Alberto
Date: 2024
Persistent ID: http://hdl.handle.net/10400.22/26401
Origin: Repositório Científico do Instituto Politécnico do Porto
Subject(s): Hypothalamic hamartoma; Epilepsy; Connectivity; Focal cortical dysplasia; Adaptative direct transfer function; Electroencephalography; Independent component analysis
Gelastic seizures are rare manifestations of epilepsy that are often associated with hypothalamic hamartomas (HH). In the absence of HH, location of the origin is more difficult and there are several less well-established possibilities. Non-invasive assessment is often complicated by the deep localization of the epileptogenic area and the complex dynamics of spike activity. Robust neurophysiological methods and careful validation of intrinsically epileptogenic lesions detected by RM can improve the validity of scalp EEG analysis. This presentation will discuss a case report analysing the dynamics of epileptic activity in gelastic seizures associated with cortical dysplasia. The clinical case was a 26-year-old girl with daily refractory gelastic seizures since the age of 6 who underwent neurophysiological examination with long-term EEG recordings and MRI of the brain. She had previously been rejected in an epilepsy surgery programme because no structural brain lesion had been found and the EEG information was not conclusive enough. A recent 3T MRI showed cortical dysplasia in the cingulate gyrus, which was highly suspicious as an epileptogenic focus. We analysed the 31-channel EEG (ictal and interictal) using source and functional connectivity methods to obtain a solid computer model of the origin and dynamics of the epileptic activity and correlate it with the anatomical information of the MRI. Source analysis of the interictal activity revealed multiple sources that dominated at different time points, suggesting considerable dynamics that prevented clear identification of the source. The ictal recordings showed little late rhythmic activity over the frontal areas, but no early focalization. Connectivity analysis, which revealed the flow of information between cortical sources, showed a consistent origin of epileptic activity near the cortical dysplasia for both interictal and ictal activity. EEG connectivity analysis significantly improves the performance of non-invasive methods for determining the intracranial dynamics of epileptic activity and correlation with structural lesions.
