American Congress of Rehabilitation Medicine Diagnostic Criteria for Traumatic Brain Injury
According to the American Congress of Rehabilitation Medicine (ACRM), traumatic brain injury (TBI) is diagnosed when at least ONE of the following criteria is met following a traumatic force to the head:
- Any period of loss of consciousness less than 30 minutes with Glasgow Coma Scale (GCS) score of 13-15 after this period
- Any loss of memory for events immediately before or after the accident (posttraumatic amnesia) lasting less than 24 hours
- Any alteration in mental state at the time of the accident (feeling dazed, disoriented, or confused) 1
Classification of TBI Severity
The severity of TBI is primarily classified using the Glasgow Coma Scale:
| GCS Score | TBI Severity |
|---|---|
| 13-15 | Mild |
| 9-12 | Moderate |
| 3-8 | Severe |
Diagnostic Considerations
Mild TBI (mTBI) Assessment
- Loss of consciousness: Document duration (must be <30 minutes for mild TBI)
- Posttraumatic amnesia: Assess duration (must be <24 hours for mild TBI)
- Mental state alterations: Document confusion, disorientation, or feeling dazed at time of injury 1
- GCS score: Must be 13-15 for mild TBI classification
Complicated vs. Uncomplicated mTBI
- When focal lesions are found on CT or MRI in a patient otherwise meeting mild TBI criteria, the term "complicated mild TBI" is used 2
- Approximately 3-13% of patients with GCS 15 will have acute lesions on head CT 1
Clinical Implications
The ACRM definition is intentionally broad to capture the full spectrum of mild TBI, which has important implications for:
- Acute management: Even with mild TBI, approximately 1% of patients will require neurosurgical intervention 1
- Long-term outcomes: Up to 15% of patients with mild TBI may have compromised function 1 year after injury 1
- Neuropsychological impact: Patients with intraparenchymal lesions may perform similarly to those with moderate TBI on neuropsychological testing, despite having GCS scores of 13-15 1
Limitations of Current Classification
The ACRM definition has some limitations:
- Relies heavily on self-reported symptoms
- May not capture subtle cognitive or behavioral changes
- Does not account for cumulative effects of multiple mild TBIs
- Does not incorporate advanced neuroimaging findings that may detect injuries not visible on conventional CT 1
Recent Developments
Recent expert panels have recommended enhancing TBI characterization beyond just the GCS score to include:
- Detailed documentation of eye, verbal, and motor GCS components
- Pupillary reactivity (recorded separately from GCS)
- Duration of post-traumatic amnesia using validated tools
- Acute symptoms using standardized rating scales
- Injury mechanism and acute physiological insults
- Biopsychosocial-environmental factors 3
The ACRM criteria remain the foundation for TBI diagnosis, but ongoing research continues to refine our understanding and classification of this complex condition.