Traumatic Brain Injury

Definition and Classification

• Traumatic brain injury (TBI) is defined as an alteration in brain function or evidence of brain pathology caused by an external force, resulting in temporary or permanent impairment of neurological and cognitive functions, according to the American College of Critical Care 1
• TBI is characterized by the presence of at least one of the following criteria: loss of consciousness, loss of memory, or alteration in mental state, with a Glasgow Coma Scale (GCS) score of 13-15, as defined by the American Academy of Emergency Medicine 2, 3
• The American College of Neurology recommends classifying TBI mainly according to the GCS into mild (13-15), moderate (9-12), and severe (3-8), complemented by imaging findings and clinical characteristics for optimal management 4, 2

Pathophysiological Processes

• The primary injury in TBI occurs at the moment of traumatic impact, resulting from immediate mechanical damage to brain tissue and blood vessels, including contusions, lacerations, hematomas, and diffuse axonal injury, which is not modifiable with medical interventions 1
• The secondary injury develops hours or days after the initial trauma, representing a pathophysiological cascade that can worsen neurological damage and prognosis, including alterations in vascular and cerebral blood flow, systemic complications, and cerebral edema 1

Epidemiology and Public Health Impact

• TBI is a significant public health burden, affecting approximately 60 million people worldwide annually, with main causes including traffic accidents, falls, assaults, and sports injuries 1, 5
• Up to 15% of patients with mild TBI may have compromised function one year after injury, and up to 50% may not recover pre-injury levels of health and well-being within 6 months, according to the American Academy of Neurology 4, 2
• TBI is one of the leading causes of death and disability in people under 45 years old, emphasizing the need for understanding its pathophysiological mechanisms to develop targeted therapeutic strategies and improve clinical outcomes 1, 5

Clinical Evaluation and Management

• The initial clinical evaluation of TBI patients should include GCS assessment, neurological examination, and signs of skull base fracture, according to the American College of Emergency Physicians 2
• The American College of Radiology recommends immediate non-contrast CT scan of the brain and cervical spine in severe TBI patients, and consideration of CT angiography in patients with risk factors for vascular injury 6
• The American College of Surgeons recommends observation, CT scan, and clinical evaluation for mild TBI patients, and immediate CT scan, continuous neurological monitoring, and consideration of ICU admission for moderate to severe TBI patients 2, 6
• Patients with severe TBI should be managed in specialized centers with neurosurgical capabilities, according to the American Association of Neurological Surgeons 6

Long-term Consequences and Complications

• TBI patients are at increased risk of post-concussion syndrome, cognitive deficits, epilepsy, stroke, and neurodegenerative diseases, according to the National Institute of Neurological Disorders and Stroke 4
• The GCS score is used to classify TBI severity, with mild TBI having a GCS score of 13-15, moderate TBI having a GCS score of 9-12, and severe TBI having a GCS score of 3-8 4, 2