Incidence of reversible cerebral vasoconstriction syndrome (RCVS) is associated with cold weather variables and is more likely to occur in the winter months in Taiwan, according to a study published in Headache.
In this retrospective study, investigators analyzed data from a cohort of patients with established RCVS (n=226) and probable RCVS (n=72) who were recruited from the headache clinic, neurology wards, and emergency department of Taipei Veterans General Hospital between March 2005 and February 2014. Patients also fulfilled the diagnostic criteria for a headache attributed to RCVS, as proposed by the International Classification of Headache Disorders, 3rd edition. Patients with diagnoses of ≥2 thunderclap headaches consistent with RCVS and an initial normal magnetic resonance angiography were classified as probable RCVS, if all other possible causes were excluded.
The numbers of new incident RCVS and probable RCVS were calculated each month. Investigators obtained meteorological data from the Central Weather Bureau of Taiwan collected repeatedly from the same weather stations in Taipei, which included monthly averaged measurements of mean, minimum, and maximum daily temperatures, total daily precipitation, average daily relative humidity, daily barometric pressure, daily maximum wind speed, and days with precipitation per month.
The incidence of total RCVS was found to be higher in the winter (3.3 persons/month) than in the summer (2.1 persons/month). Compared with probable RCVS, the incidence of definite RCVS was higher in the winter (2.6 persons/month) than in the summer (1.6 persons/month, P =.021). The mean temperatures in summer and winter in Taipei were 27.9°C (standard deviation [SD] 1.9) and 18.6°C (SD 2.6), respectively. New cases of RCVS per month correlated negatively with mean daily temperature in bivariate correlation analysis (r=-0.231, P =.016) and mean precipitation (r=-0.269, P =.005), but correlated positively with barometric pressure (r=0.274, P =.004).
While this study included one of the largest cohorts of patients with RCVS ever reported, it is limited by the fact that all data derived from patients of the same ethnicity visiting a single headache center.
The investigators suggested that more research is needed to fully elucidate the incidence of RCVS in regions with different climates.
Shih YC, Chen SP, Fuh JL, Wang YF, Wang SJ. Influence of climate on the incidence of RCVS – a retrospective study from Taiwan [published online March 13, 2019]. Headache. doi: 10.1111/head.13504