FIG. 1.

Traumatic brain injury (TBI) of varying severities can result in acute impairments in multiple domains of function. The degree of impairment can range from mild transient symptoms to prolonged disordered consciousness and death. The degree and rate of recovery is similarly variable. Some survivors may continue to improve for years following injury. Most reach a recovery plateau, after which some remain stable while others experience a progressive decline in one or more area of function (post-traumatic neurodegeneration [PTND]).