THE EFFECT OF CHANGES IN BAROMETRIC-PRESSURE ON THE RISK OF RUPTURE OF INTRACRANIAL ANEURYSMS

Several meteorological variables have been linked with an altered inci dence of cerebrovascular disease. In particular, we had noticed that, following abrupt changes in weather, patients with aneurysmal subarach noid haemorrhage (SAH) often presented in groups. This study was under taken to determine whether changes in barometric pressure would be an important factor. A retrospective analysis of a two year period was ca rried out. Daily mean, peak and trough atmospheric pressures had been recorded independently by a weather bureau. Of the 157 patients with S AH due to a berry aneurysm, confirmed by CT and angiography, 60 were e ntered into the study. Patients residing outside the weather bureau re gion (n = 86), or where there was uncertainty of their day of ictus (n = 11), were excluded. Daily peak to trough pressure changes and mean monthly pressure fluctuations showed no association with an increased risk of SAH. However, a significant relationship between the incidence of onset of symptoms indicative of a rupture of the aneurysm and a ch ange in barometric mean pressure (BMP) of > 10 hectapascals from the p revious day was found (p = 0.0247). The calculated odds ratio of susta ining a SAH with this associated BMP change was therefore 2.7 times wi th a risk of 1-13 times at a 95% confidence level (p = 0.035).