Interictal spike EEG source analysis in hypothalamic hamartoma epilepsy

• Published in: Clinical neurophysiology Vol. 113; no. 12; pp. 1961 - 1969
• Main Authors: Leal, Alberto J.R, Passão, Vitorina, Calado, Eulália, Vieira, José P, Silva Cunha, João P
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 01-12-2002; Elsevier Science
• Subjects: Action Potentials - physiology; Adult; Biological and medical sciences; Child; Child, Preschool; Electric; Electroencephalography - methods; Electroencephalography - statistics & numerical data; Epilepsy; Epilepsy - pathology; Epilepsy - physiopathology; Female; Hamartoma - pathology; Hamartoma - physiopathology; Humans; Hypothalamic hamartoma; Hypothalamus - physiopathology; Male; Medical sciences; Neurology; Source analysis; Tumors of the nervous system. Phacomatoses; Hypothalamic hamartoma; Electric; Source analysis; Epilepsy; Human; Pseudotumor; Spike; Nervous system diseases; Exploration; Interictus; Male; Electroencephalography; Hypothalamus; Nuclear magnetic resonance imaging; Cerebral disorder; Hamartoma; Case study; Electrodiagnosis; Central nervous system disease; Medical imagery; Complication; Female; Benign neoplasm; Child
• ISSN: 1388-2457; 1872-8952
• DOI: 10.1016/S1388-2457(02)00253-5

Objective: The epilepsy associated with the hypothalamic hamartomas constitutes a syndrome with peculiar seizures, usually refractory to medical therapy, mild cognitive delay, behavioural problems and multifocal spike activity in the scalp electroencephalogram (EEG). The cortical origin of spikes has been widely assumed but not specifically demonstrated.
Methods: We present results of a source analysis of interictal spikes from 4 patients (age 2–25 years) with epilepsy and hypothalamic hamartoma, using EEG scalp recordings (32 electrodes) and realistic boundary element models constructed from volumetric magnetic resonance imaging (MRIs). Multifocal spike activity was the most common finding, distributed mainly over the frontal and temporal lobes. A spike classification based on scalp topography was done and averaging within each class performed to improve the signal to noise ratio. Single moving dipole models were used, as well as the Rap-MUSIC algorithm.
Results: All spikes with good signal to noise ratio were best explained by initial deep sources in the neighbourhood of the hamartoma, with late sources located in the cortex. Not a single patient could have his spike activity explained by a combination of cortical sources.
Conclusions: Overall, the results demonstrate a consistent origin of spike activity in the subcortical region in the neighbourhood of the hamartoma, with late spread to cortical areas.