Early surgery is not always the best treatment for one of the most common and potentially lethal types of stroke, researchers have found.
Stroke patients are often left disabled despite surgery
A team at Newcastle University has discovered that in many cases careful observation is better than an operation to remove blood clots.
Scientists studied 1,000 patients in 27 countries and their study is published in the Lancet journal on Friday.
They found surgery did not always make a difference to whether people died.
By studying statistics they discovered that avoiding surgery led to no difference in the number of patients who did not survive or the degree of disability they suffered.
They also found that surgery is most helpful to patients with blood clots near the surface of the brain, and of least benefit to those in a coma.
Dr David Mendelow, who led the research, said: "The results will help us decide better how to manage patients with this type of stroke.
"Careful clinical observation and surgery can be life-saving but there's no need to rush in with an operation, except perhaps in those patients where the blood clot is significantly closer to the surface.
"This type of clot should not be confused with the type of clot that occurs after an injury."
Strokes are caused by a sudden rupture of a blood vessel in the brain.
Current treatment recommends early surgery to remove clots to limit damage to let blood flow more freely.
Dr Joanne Knight, of the Stroke Association, said: "We're pleased to learn this research will now give consultants the evidence they need to decide on the best treatment for stroke patients."