Cerebral venous sinus thrombosis cases detected in on-call CT venographies in Sweden, 2019-2022.

No well-established criteria exist for assessing the risk of cerebral venous sinus thrombosis (CVST). Here, we sought to gain an understanding of CVST cases and associated risk factors, based on the rates of emergency CT venographies (CTVs) performed after hours. Furthermore, we aimed to assess possible correlations between CVST rates and COVID-19, including at the start of the COVID-19 vaccination campaign. We collected reports of emergency CTVs performed after hours at 56 Swedish hospitals between 1/1/2019 and 12/31/2022, and divided them into five groups: (I) from 1/1/2019 to 1/31/2020, before the emergence of COVID-19 cases in Sweden; (II) from 2/1/2020 to 12/26/2020, after the emergence of COVID-19 but before vaccination rollout; (III) from 12/27/2020 to 7/28/2021, from the start of the COVID-19 vaccination campaign until 50% of the adult population in Sweden had been vaccinated; (IV) from 7/29/2021 to 2/1/2022, from when 50% of the adult population was vaccinated until restrictions were lifted; and (V) from 2/2/2022 to 12/31/2022, after restriction measures were suspended. For all included patients, we collected information on demographics and clinical history, including pregnancy, recent partum, and use of oral contraceptives or post-menopausal hormone replacement therapy. In total, we collected 430 reports (92% female, 8% male). The CVST positivity rate was 22.2% in men vs. 2.3% in women. None of the pregnant (n = 49) or postpartum (n = 12) women had CVST positivity. The frequency of CTV examinations was lowest in group 2; during this period, the average time between patients being imaged was 7 days. The frequency of CTV examinations was highest in group IV; during this period, a patient underwent this type of scan every 1.5 days, on average. The frequency of CVST-positive scans was lowest in group II; during this period, a positive case was found every 66 days, on average. The frequency of CVST-positive scans was highest in group IV; during this period, a positive case was found every 62 days, on average, and no statistical difference with respect to group II was observed. Pregnancy and recent partum were not significant risk factors for CVST. The elevated CVST positivity rate observed during the height of the COVID-19 pandemic suggested that patients with less likelihood for positive CVST had fewer emergency visits. The positivity rate did not increase with the start of the COVID-19 pandemic or the rollout of COVID-19 vaccination.