Mild head injury: differences in prognosis among patients with a Glasgow Coma Scale score of 13 to 15 and analysis of factors associated with abnormal CT findings.

We performed a retrospective study of 2484 consecutive patients with mild head injury (Glasgow Coma Scale score 13-15) who were seen during a period of 18 months. Of these, 2351 (94.6%) patients scored 15 points, 88 (3.5%) scored 14 points and 45 (1.3%) 13 points. A multivariate analysis showed that advanced age, a lower GCS (13-14) and the presence of skull fracture, and focal signs, significantly increased the incidence of abnormal computed tomography (CT) findings. By contrast, the gender, the mechanism of injury, the occurrence of initial loss of consciousness, posttraumatic amnesia and coagulation disorders did not significantly increase the incidence of abnormal CT findings. Patients with 13-14 GCS had a significantly higher incidence of initial loss of consciousness, of skull fracture, abnormal CT findings, need for hospital admission, delayed neurological deterioration and need for operation than patients with a GCS of 15. Thus, we suggest separating patients with a GCS of 13-14 into a different category and recommend performing CT in all those not improving within 4-6 h of injury. Such a policy makes skull radiography unnecessary in this subgroup. By contrast, skull radiographs may be useful for the triage of patients with a GCS of 15 that represent most of the mild head injury cases; radiographs should be obtained in patients presenting with initial loss of consciousness or posttraumatic amnesia (27.9% of the total cases) as these two findings were associated with a significantly higher incidence of fracture. Patients without these two findings (72.1% of the cases) showed a very low incidence of skull fracture (0.9% in this study) and may be discharged home with a warning sheet.