**2.1 Definition of a mild head injury**

A mild head injury can be defined as an injury caused by blunt trauma and/or sudden acceleration /deceleration which produces a period of unconsciousness for 20 minutes or less, a Glasgow coma scale score of 13-15, no focal neurological deficit, no intracranial complications and computed tomographic findings limited to a skull fracture without evidence of contusion or hematoma.Despite the dissemination of information that is available on diagnostic criteria, controversies still exist in defining mild head injury and collecting patients.

Estimating the duration of unconsciousness is difficult when witnesses are not available, second if the patient is intoxicated at the time of hospital admission it can obscure the assessment of severity of head injury.
