Subarachnoid haemorrhage research: new study explores trigger factors

06 May 2011

A new scientific study explores some of the activities that triggered a ruptured brain aneurysm (subarachnoid haemorrhage) in 250 patients. These include drinking coffee, vigorous exercise and blowing your nose. But more research is needed before we fully understand whether such activities can directly cause a brain aneurysm to burst.

What is a ruptured brain aneurysm (subarachnoid haemorrhage)?


A brain aneurysm is a balloon-like swelling in the wall of an artery supplying blood to the brain. It is unlikely that people will know that they have a brain aneurysm unless it ruptures (bursts) and they have a bleed on the brain (a subarachnoid haemorrhage).

Subarachnoid haemorrhage occurs when the aneurysm wall tears because of the pressure of the blood as it is pumped through the brain. When this happens, blood bursts into the surrounding brain tissue. It is a very serious, life-threatening condition and a medical emergency.

Identifying triggers


We already know that subarachnoid haemorrhage often, though not always, happens at a time of physical effort like coughing, going to the toilet, heavy lifting, straining, or during sex. This study, Trigger Factors and Their Attributable Risk for Rupture of Intracranial Aneurysms, aimed to identify and quantify triggers like these.

It did this by asking 250 patients who had experienced a subarachnoid haemorrhage to fill in a questionnaire, asking them about 30 potential trigger factors and whether they were exposed to these just before their bleed.

Results of the research


According to the researchers, who were based in the Netherlands, 8 activities increased the risk for subarachnoid haemorrhage. These were:

  • coffee consumption

  • cola consumption

  • anger

  • being startled

  • straining for defecation

  • sexual intercourse

  • nose blowing, and

  • vigorous physical exercise


"All triggers induce a sudden and short increase in blood pressure, which seems a possible common cause for aneurysmal rupture," said Dr Monique Vlak, a neurologist who worked on the study.

Could be coincidence


However, more research is needed in order to examine the triggers for a subarachnoid haemorrhage.

Quoted on the BBC website, Dr Sharlin Ahmed, Research Liaison Officer at The Stroke Association said: "A sudden surge in high blood pressure can increase the likelihood of an aneurysm rupturing. However, it's very difficult to determine whether the triggers identified in this study are definitely related to the onset of a stroke as they could simply be put down to coincidence.

"A lot more research needs to be carried out to assess whether each of the identified triggers could directly cause an aneurysm to rupture."

Brain and Spine Helpline Manager Angela Collett said: "This is an interesting piece of research, which highlights the possible activities which raise blood pressure. I would however draw attention to the number of people who are NOT undertaking any of these activities and who have aneurysmal bleeds. More research is required."

No need to avoid coffee, sex and blowing your nose


The NHS "Behind the Headlines" website commented: "The news headlines may give people the wrong impression that they should avoid drinking coffee, sex and blowing their nose to reduce their risk of having a stroke, and this is not the case.

"As the study highlights, only about 2% of the population have an intracranial aneurysm and only a few of these actually rupture. As such, though some triggers could potentially be avoided to try and reduce the risk of rupture, this would only be of relevance to people who are known to have an aneurysm within the skull. The vast majority of the population would not be at increased risk from carrying out any of these activities because they do not have an intracranial aneurysm."

Get more information


If you have any questions about subarachnoid haemorrhage or any other neurological topic, call the Brain and Spine Helpline on 0808 808 1000 or email helpline@brainandspine.org.uk.

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