Each year, worldwide, many thousands of people are treated in emergency departments for head injuries. Mannitol is an osmotic diuretic that is believed to reduce intracranial pressure after head injury and may improve patient outcome. Between 2001 and 2004, a Brazilian neurosurgeon Julio Cruz and colleagues published three clinical trials comparing high dose and conventional dose mannitol in the treatment of head injury (table⇓).123 No other trials had examined this question.

The results showed that high dose mannitol greatly reduced death and disability six months after the head injury. A Cochrane systematic review that included these trials concluded: “high dose mannitol seems to be preferable to conventional dose mannitol in the acute management of comatose patients with severe head injury.”4 However, one of the trials was accompanied by an editorial that questioned the reliability and validity of the results, calling for further multicentre studies.5 A subsequent investigation by the Cochrane Collaboration was unable to confirm that the studies took place.