This table from the VA/DoD Clinical Practice Guideline for the Management of Concussion-mild Traumatic Brain Injury shows criteria for evaluating the severity of TBI when it is first diagnosed. It's important to remember that the severity of TBI at the time of diagnosis does not necessarily determine the extent of long-term functional impairment. Select Play to hear subject matter experts discuss ways that residuals evaluated by a C&P examiner may be related to the initial severity of a TBI.

Criteria	Mild	Moderate	Severe
Structural imaging	Normal	Normal or abnormal	Normal or abnormal
Loss of Consciousness (LOC)	0-30 min	Greater than 30 min and less than 24 hours	Greater than 24 hours
Alteration of consciousness / mental state (AOC)*	Up to 24 hours	Greater than 24 hours; severity based on other criteria	Greater than 24 hours; severity based on other criteria
Posttraumatic amnesia (PTA)	0-1 day	Greater than 1 day and less than 7 days	Greater than 7 days
Glasgow Coma Scale (GCS)** (best available score in first 24 hours)	13-15	9-12	Less than 9

*Alteration of mental status must be immediately related to the trauma to the head. Typical symptoms would be looking and feeling dazed and uncertain of what is happening, confusion, and difficulty thinking clearly or responding appropriately to mental status questions and being unable to describe events immediately before or after the trauma event.

**In April 2015, the Assistant Secretary of Defense released a memorandum, Traumatic brain injury: Updated definition and reporting, that recommended against the use of GCS scores to diagnose TBI.