title: Interictal spike EEG source analysis in hypothalamic hamartoma epilepsy.
abstract: 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.
authors.affiliation: Department of Neurology, Hospital Fernando Fonseca, IC19, 2700 Amadora, Portugal. a.leal@netcabo.pt
authors.forename: Alberto J R
authors.initials: AJ
authors.lastname: Leal
authors.forename: Vitorina
authors.initials: V
authors.lastname: Passão
authors.forename: Eulália
authors.initials: E
authors.lastname: Calado
authors.forename: José P
authors.initials: JP
authors.lastname: Vieira
authors.forename: João P
authors.initials: JP
authors.lastname: Silva Cunha
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000328:Adult; D002648:Child; D002675:Child, Preschool; D004569:Electroencephalography / Q000379:methods* / Q000706:statistics & numerical data; D004827:Epilepsy / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D006222:Hamartoma / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D007031:Hypothalamus / Q000503:physiopathology*; D008297:Male