title: Infantile spasms: seasonal onset differences and zeitgebers.
abstract: The health records of 76 infants with infantile spasms (IS) were reviewed retrospectively. The distribution of seizure onset was examined with respect to calendar month, annual changes in day length (photoperiod), and global solar radiation (GSR). IS onset was more frequent during the months with low GSR and short photoperiods. The greatest frequency of IS onset was in December and January (22 cases, 29%); the lowest was in April and May (8 cases, 10.5%). IS onset frequency (f) was more than twice as great in the months with a short photoperiod (10Light-14Dark) and a low GSR (f = 11) as compared with months with a long photoperiod (16Light-8Dark) and a high GSR (f = 5). IS onset frequency was 2.2-fold greater in months with a short photoperiod and a low GSR. This finding suggests that environmental photoperiodic factors (zeitgebers) may play a role in the onset of IS.
authors.affiliation: Department of Pediatrics, Hospital for Sick Children, University of Toronto, Ontario, Canada.
authors.forename: M A
authors.initials: MA
authors.lastname: Cortez
authors.forename: W M
authors.initials: WM
authors.lastname: Burnham
authors.forename: P A
authors.initials: PA
authors.lastname: Hwang
mesh_terms: D004777:Environment; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D008499:Medical Records; D017440:Photoperiod; D012189:Retrospective Studies; D012621:Seasons; D013036:Spasms, Infantile / Q000453:epidemiology*; D013472:Sunlight