Mild, moderate and severe: terminology implications for clinical and experimental traumatic brain injury

Area of Science:

• Neuroscience
• Neurology
• Traumatic Brain Injury Research

Background:

• Clinical classifications of mild, moderate, and severe traumatic brain injury (TBI) are often misleading.
• Mild TBI frequently results in long-term disability, contrary to its designation.
• Severe experimental TBI in rodents often mirrors mild or complicated mild clinical TBI.

Purpose of the Study:

• To critically evaluate the current terminology used in traumatic brain injury (TBI) research.
• To highlight the discrepancies between clinical TBI severity and experimental models.
• To emphasize the need for revised classifications and translational research targets.

Main Methods:

• Review of existing literature on clinical and experimental traumatic brain injury (TBI).
• Analysis of patient outcomes and neuroimaging findings across different TBI severity levels.
• Comparison of experimental rodent TBI models with clinical TBI presentations.

Main Results:

• Mild TBI patients often exhibit persistent postconcussive symptoms, cognitive deficits, and reduced cerebral blood flow.
• Significant mortality and long-term disability (inability to return to work) are observed in moderate and severe TBI survivors.
• Neuroimaging reveals white matter damage and functional connectivity abnormalities even in clinically recovered mild TBI patients.
• Experimental rodent TBI, regardless of defined severity, aligns more closely with mild or complicated mild clinical TBI.

Conclusions:

• The terms mild, moderate, and severe are inadequate for describing TBI, necessitating a re-evaluation of classifications.
• Patients with mild or moderate TBI experience significant long-term sequelae, highlighting them as crucial targets for translational research.
• Therapeutic strategies effective in experimental rodent TBI models may be highly relevant for treating mild to moderate clinical TBI.