British medical authorities state they have found 30 cases after 18 million of AZ vaccine doses administered. That is 1.7 cases per million doses. Assume those doses have been given during two months, then given the same frequency of vaccination we would expect to see 10 cases / million /year.
According to this paper the orthodox view is that the frequency of CSV thrombosis is 2 - 5 cases / million / year. However, a recent study in Netherlands has shown a higher incidence. And the paper I referenced above (an Australian study) finds the incidence even higher: roughly 15 cases / million / year. If these modern studies are correct, then there is so far no evidence that the incidence of CSV thrombosis is increased after vaccination with the AZ vaccine. However, vigilance must be maintained.