Stroke that occurs on the right-side of the brain may be going untreated, according to research published in the Lancet.
German researchers found that left-sided stroke patients were more likely to be admitted to hospital and treated for symptoms than those people suffering from the condition of the right side of their brain.
The researchers believe that because right-sided strokes do not affect speech, they may go unnoticed for longer.
The right side of brain is responsible for making sense of what a person sees and hears, and spatial skills, judging distance and depth.
Study leader Dr Christian Foerch from the Johann Wolfgang Goethe University in Frankfurt observed over 20,000 patients between 1997 and 2002.
It was found that the majority of recorded stroke cases were left-sided and right-sided cases were more often missed.
Those people suffering from a left-sided stroke were also more likely to receive hospital treatment within three hours of symptoms initiating.
The research team wrote: "The probable explanation for our findings is that symptoms... are more noticeable if language or dominant hand function is affected, both of which are located in the left hemisphere in most individuals."
Stroke is one of the leading killers in the UK, with one person every five minutes affected.