title: Hypothalamic hamartoma: basic mechanisms of intrinsic epileptogenesis.
abstract: The hypothalamic hamartoma (HH) is a rare developmental malformation commonly associated with gelastic seizures that are notoriously refractory to medical therapy. Recent evidence supports the intrinsic seizure propensity of HH. Despite increasing clinical recognition of this condition, the mechanisms of seizure genesis in HH tissue remain unclear. This review summarizes the histochemical and electrophysiological properties of HH neurons, and relates these findings to those characteristics identified in other types of epileptic tissue. Initial studies have revealed two distinct populations of neurons in surgically resected HH tissue. One group consisted of small gamma-aminobutyric acid (GABA)-expressing neurons that occurred principally in clusters and displayed spontaneous rhythmic firing. The second group was composed of large, quiescent, pyramidal-like neurons with more extensive dendritic and axonal arborization. We propose that the small, spontaneously firing GABAergic neurons send inhibitory projections to and drive the synchrony of large output neurons. These observations constitute the basis for future investigations aimed at elucidating the mechanisms of subcortical epileptogenesis.
authors.affiliation: Division of Neurology and Pediatric Neurology, Barrow Neurological Institute and Children's Health Center, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA. kristina.fenoglio@chw.edu
authors.forename: Kristina A
authors.initials: KA
authors.lastname: Fenoglio
authors.forename: Jie
authors.initials: J
authors.lastname: Wu
authors.forename: Do Young
authors.initials: DY
authors.lastname: Kim
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Simeone
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Coons
authors.forename: Harold
authors.initials: H
authors.lastname: Rekate
authors.forename: Jong M
authors.initials: JM
authors.lastname: Rho
authors.forename: John F
authors.initials: JF
authors.lastname: Kerrigan
mesh_terms: D000200:Action Potentials / Q000502:physiology; D004827:Epilepsy / Q000209:etiology* / Q000473:pathology; D006222:Hamartoma / Q000150:complications* / Q000473:pathology; D006801:Humans; D007027:Hypothalamic Diseases / Q000150:complications* / Q000473:pathology; D007031:Hypothalamus / Q000473:pathology; D015640:Ion Channel Gating / Q000502:physiology; D009474:Neurons / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D005680:gamma-Aminobutyric Acid