Skull X-rays after mild head injuries.

More than a million recently head-injured patients present at accident and emergency (A&E) departments in Britain each year. All but 5% are fully conscious on arrival but, on careful questioning, one in six of these mildly injured patients will admit to amnesia for a short period after injury; some will be reported as having been briefly unconscious. Controversy about the management of these many mildly injured patients centres on how best to minimize avoidable mortality and morbidity from acute intracranial haematoma. A good outcome after this complication depends on early diagnosis and rapid surgical evacuation of the clot. The problem is that this complication develops in only about one in a thousand attenders, as Gorman's large study confirms (pp. 141150). The problem is identifying the level of risk in different types of patient so as to avoid the unnecessary admission of large numbers of low-risk patients. Haematomas are much less common in children, who make up about half of head-injured A&E attenders but only one in ten of patients who develop a haematoma (Jennett & Teasdale, 1981). The incidence is three times greater in patients over 65 years than in younger people (Pentland & Roy, 1987); in this age group haematomas are easily overlooked in favour of stroke (Galbraith, 1987). Traditional teaching has been that all patients with a history of even brief post-traumatic amnesia are at risk and should be admitted. However, statistical analysis of several thousand adult patients from A&E departments and primary surgical wards in Scotland has shown that a fracture of the skull is a more important risk factor for haematoma than is briefly altered consciousness (Mendelow et al., 1983). This is confirmed by Gorman's study as well as by several reports from other countries. The significance of a fracture is greatest after mild injuries, in whom the risk in adults is otherwise very small (1:6000); with a fracture, the risk rises to about one in 300. Guidelines have recommended that fully conscious adults in whom a fracture has been excluded with reasonable certainty can safely be sent home (Neurosurgeons, 1984). Their application has resulted in reducing admissions in some hospitals by a half or more, which means a considerable saving in resources for the NHS and in inconvenience for patients and their families (Mendelow et al., 1982). The most controversial issue is the role of skull X-rays in making decisions about mild injuries. Most of these decisions are made by A&E staff, but the protagonists in the controversy are mostly radiologists and neurosurgeons. The importance of Gorman's study is its size, its location in a district general hospital and the careful analysis of the controversy as seen from the A&E department. He comments on how radiologists on both sides of the Atlantic have been complaining about what they see as the indiscriminate and unnecessary use of skull X-rays after mild head injury. They point to the low yield of fractures after mild injuries, which is true; and they allege that no important decisions derive from finding a fracture, which is not true. Moreover, there is evidence that clinicians already exercise considerable restraint in ordering skull X-rays: in Gorman's study 44% were X-rayed and in the Glasgow survey of Scotland it was 58%. coright.