see also traumatic brain injury definition
The most frequently used definition of mild traumatic brain injury is a GCS score between 13-15 and loss of consciousness of less than 30 minutes or amnesia not extending beyond 24 hours after blunt head injury 1).
Traditionally, mild head injury has been defined as GCS ≥ 13. However, the increased frequency of both surgical lesions and CT scan abnormalities in patients with GCS=13 suggests that they would be better classified with moderate rather than mild head injuries 2).