Circannual incidence of seizure evacuations from the Canadian Arctic

Circannual seizure provocation as the day lengthens in the northern and southern hemispheres

“…been published previously. 2,6 At the northern site, an EEG database identified 99 persons aged ≥16 years who had seizures requiring 117 medical evacuations from the Arctic from September 2009 to November 2020 for subsequent EEG. 7 At the southern site, a prospective study was undertaken (with retrospective chart review to ensure no cases were missed) to identify 367 persons aged 4 weeks or older from 6 April 2015 to 5 April 2016 who had 477 presentations of continuous seizure lasting at least 10 minutes, or repeated seizures exceeding 10 min without recovery.…”

“…The southern site comprised five public hospitals and the major private hospital in Greater Auckland, New Zealand 6 . Methods used to identify SE cases have been published previously 2,6 . At the northern site, an EEG database identified 99 persons aged ≥16 years who had seizures requiring 117 medical evacuations from the Arctic from September 2009 to November 2020 for subsequent EEG 7 .…”

“…For example, in the Arctic, solstices can be characterized by 24 h of sunlight in summer and 24 h of darkness in winter. In the Kivalliq region of the Canadian Arctic territory of Nunavut, there is a circannual peak of SE cases maximally after the winter solstice, through the spring equinox, and before the summer solstice 2 as daily light exposure increases. While supporting the notion that re-emergence of the sun following near-24 h of darkness interrupts sleep to facilitate occurrence and severity of seizures, [3][4][5] these data were also subject to numerous factors that potentially confounded the timing of SE occurrence.…”