Definition and epidemiology of mild traumatic brain injury

The definition of mild traumatic brain injury (mTBI), also known as concussion, has been a matter of controversy, which makes comparison between studies difficult. Incidence varies greatly from one country to another. The present article reviews definitions and epidemiology.

Literature review.

According to the Mild TBI Committee of the American Congress of Rehabilitation Medicine, revised by the World Health Organization (WHO), mTBI is defined by a Glasgow Coma Scale score between 13 and 15 at 30minutes post-injury, and one or more of the following symptoms: <30min loss of consciousness; <24hours post-traumatic amnesia (PTA); impaired mental state at time of accident (confusion, disorientation, etc.); and/or transient neurological deficit. If a focal lesion is found on computed tomography (CT) or magnetic resonance imaging (MRI), the term "complicated mild TBI" has been proposed. Incidence of mTBI is 200-300/100,000 persons per year for hospitalized patients and probably twice as high if non-hospitalized patients are included. However, a few recent population-based studies reported a much higher rate (>700/100,000). A changing pattern of epidemiology has been found in high-income countries, related to a decrease in road-accident injuries in young adults, while conversely the proportion of falls has increased with population aging.

Mild TBI is a major public health concern, the epidemiology of which has greatly changed in the last twenty years.