Introduction

Head injuries constitute a major health problem in industrialized countries. In the United States approximately 100 000 people die each year as a result of head injury (Department of Health and Human Services February, 1989). Many thousands are left with serious lifetime residual disabilities. However, reliable statistics of incidence are difficult to obtain because some of the fatal cases never reach the hospital, while many with milder injuries do not seek medical attention unless complications develop. Nevertheless, the overall estimate of incidence based on United States studies is approximately 200 per 100 000 population per year (Kraus 1993; Sorenson & Kraus 1991). There are approximately 450 000 patients hospitalized in the United States for head injury each year. A great majority of these are mild head injuries where the period of unconsciousness can often be measured in seconds or minutes. Moderate and severe head injuries each contribute approximately 10% (Kraus et al. 1984). These figures imply that someone suffers a head injury in the United States every 15 seconds, and that every 5 minutes one of these individuals will die and another will become permanently disabled.

Transport-related events are the single largest cause of head injury. These events include motor vehicle accidents (50–60%), motorcycle accidents (20%), bicycle accidents (12%) and pedestrian injuries (Kraus et al. 1984). Falls are the second leading cause rated in most studies (Annegers et al. 1980b; Jagger et al. 1984; Klauber et al. 1981; Kraus et al. 1984)