The Abbreviated Injury Scale (AIS), is another tool used in the assessment of brain injury severity. In contrast to the GCS, the AIS is an anatomical scoring system which ranks each anatomic region on a 1-6 ordinal scale (from minor to maximal) using neuroradiological or operative findings.
The AIS was first published in 1971 and has been continuously improved since its inception. It was updated in 2005 and 2008. It is usually used in conjunction with the Injury Severity Score which assesses patients involved in traffic accidents.
| Injury Severity | Abbreviated Injury Score |
| minor injury | 1 |
| moderate injury | 2 |
| severe but not life-threatening | 3 |
| potentially life-threatening but survival likely | 4 |
| critical with uncertain survival | 5 |
| unsurvivable injury (maximal possible) | 6 |
| severity unknown | 9 |
Injuries are assigned to 5 body regions: General, Head and Neck, Chest, Abdomen, and Extremities and Pelvis. For TBI, the Head and Neck Category is used. Each type of injury is then rated from 1-6.
Head and Neck
| cerebral injury with headache or dizziness but no loss of consciousness | head and neck | 1 |
| whiplash complaint with no anatomical or radiological evidence | head and neck | 1 |
| abrasions and contusions of ocular apparatus (lids, conjunctivae, cornea, uveal injuries) | head and neck | 1 |
| vitreous or retinal hemorrhages | head and neck | 1 |
| fractures and/or dislocation of teeth | head and neck | 1 |
| cerebral injury with/without skull fracture, less than 15 minutes unconsciousness, no post-traumatic amnesia | head and neck | 2 |
| undisplaced skull or facial bone fractures or compound fracture of nose | head and neck | 2 |
| laceration of the eye and appendages | head and neck | 2 |
| retinal detachment | head and neck | 2 |
| disfiguring lacerations | head and neck | 2 |
| whiplash severe complaints with anatomical and radiologic evidence | head and neck | 2 |
| cerebral injury with or without skull fracture, with unconsciousness more than 15 minutes, without severe neurological signs, brief post-traumatic amnesia (less than 3 hours) | head and neck | 3 |
| displaced closed skull fracture without unconsciousness or other signs of intracranial injury | head and neck | 3 |
| loss of eye | head and neck | 3 |
| avulsion of optic nerve | head and neck | 3 |
| displaced facial bone fractures or those with antral or orbital involvement | head and neck | 3 |
| cervical spine fractures without cord damage | head and neck | 3 |
| cerebral injury with or without skull fracture with unconsciousness of more than 15 minutes, with definite abnormal neurological signs; post-traumatic amnesia 3-12 hours | head and neck | 4 |
| compound skull fracture | head and neck | 4 |
| cerebral injury with or without skull fracture with unconsciousness of more than 24 hours; post-traumatic amnesia more than 12 hours | head and neck | 5 |
| intracranial hemorrhage | head and neck | 5 |
| signs of increased intra-cranial pressure (decreasing state of consciousness, bradycardia under 60, progressive rise in blood pressure, or progressive pupil inequality) | head and neck | 5 |
| cervical spine injury with quadraplegia | head and neck | 5 |
| major airway obstruction | head and neck |
The scores for TBI are totaled from the above. The mortality or death rate is then calculated using the totaled scores.
| Score | mortality rate if age ≤ 49 | mortality rate if age 50-69 | mortality rate if age ≥ 70 |
| 5 | 0 | 3 | 13 |
| 10 | 2 | 4 | 15 |
| 15 | 3 | 5 | 16 |
| 20 | 6 | 16 | 31 |
| 25 | 9 | 26 | 44 |
| 30 | 21 | 42 | 65 |
| 35 | 31 | 56 | 82 |
| 40 | 47 | 62 | 92 |
| 45 | 61 | 67 | 100 |
| 50 | 75 | 83 | 100 |
| 55 | 89 | 100 | 100 |
| data extrapolated from Figure 4, Baker et al (1974) |