Stroke: seasonal variation and association with hypertension.

A prospective study was contemplated with 155 patients of acute stroke in the Department of Neurology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, from March 1996 to February 1997. The objective of the study was to find out seasonal variation of stroke occurrence. An attempt was also made to find out the association of hypertension with ischaemic and haemorrhagic stroke during summer and winter. The numberofsubjects duringsummer and winterwere 121 and 34, respectively. In summer, out of 121 subjects, 87(71.9%) were ischaemic stroke and 34(28.1%) haemorrhagic stroke, of which 32 were intracerebral haemorrhage (ICH) and 2 subarachnoid haemorrhage (SAH). There were 18 (52.9%) ischaemic stroke and 16(47.06%) haemorrhagic stroke (all ICH) among total 34 subjects during winter. The frequency of ischaemic stroke during summer was significantly greater than that during winter (p<0.05). The frequency of haemorrhagic stroke during winter was significantly greater than that during summer (p<0.05). Temperature was positively correlated to ischaemic stroke (p<0.01) and negatively correlated to haemorrhagic stroke (p<0.1). Hypertension was significantly more associated with haemorrhagic stroke than with ischaemic stroke irrespective of season (p<0.05).