Brain Injury

Brain injury is a broad term describing any condition in which brain tissue sustains damage, whether from an external physical force — a category known as traumatic brain injury (TBI) — or from internal events such as oxygen deprivation, infection, stroke, or toxic exposure. Traumatic brain injury is the most common reason for neurosurgical referral and remains a leading cause of death and long-term disability worldwide, affecting people across all age groups and walks of life.

The clinical consequences of brain injury span an enormous range. A single mild concussion may cause nothing more than a brief headache and a day of poor concentration, while a severe injury can result in prolonged unconsciousness, permanent physical and cognitive impairment, or death. Advances in neurocritical care and structured rehabilitation have improved outcomes, making early recognition and appropriate triage critically important.

Injuries are classified by severity using the Glasgow Coma Scale (GCS), a standardized scoring system that assesses eye opening, verbal response, and motor response on a combined scale of 3 to 15. Scores of 13 to 15 indicate mild TBI (concussion); 9 to 12, moderate TBI; and 8 or below, severe TBI. Structurally, injuries are described as focal or diffuse. Focal injuries include cerebral contusions (bruising of brain tissue), epidural hematoma (arterial bleeding between the skull and the dura mater), subdural hematoma (venous bleeding beneath the dura), and intracerebral hemorrhage. Diffuse axonal injury — the most common form of diffuse damage — results from the rapid shearing and stretching of nerve fibers during acceleration-deceleration forces and may not be visible on initial CT imaging, often requiring MRI for detection.

Symptoms vary according to injury severity and the brain regions involved.

Mild TBI typically produces transient headache, dizziness, brief disorientation, nausea, fatigue, and sensitivity to light and noise, with most symptoms resolving within days to a few weeks. 

Moderate to severe TBI can cause prolonged unconsciousness, post-traumatic amnesia (a period of confusion and inability to form new memories after the injury), focal neurological deficits such as limb weakness or speech disturbance, visual changes, and profound behavioral or personality shifts.

Cognitive difficulties — including impaired memory, slowed processing speed, difficulty with attention and planning, and emotional dysregulation — are among the most persistent long-term consequences of significant brain injury and can profoundly affect quality of life and ability to return to work or independent living.

• Falls 
• Motor vehicle accidents 
• Sports-related concussion 
• Physical assault
• Industrial and workplace accidents
• Blast injuries sustained during military service

Alcohol and substance intoxication are among the most modifiable risk factors: they impair judgment and coordination, increasing the likelihood of injury, and they worsen neurological outcomes when injury occurs. Participation in high-contact sports without adequate protective equipment and evidence-based concussion protocols heightens vulnerability. A prior history of TBI is itself an independent risk factor — structural and physiological changes from an initial injury reduce the brain's resilience to subsequent trauma, and repeated impacts before full recovery carry a cumulative burden. Anticoagulant and antiplatelet medications do not raise the risk of sustaining a head injury but substantially increase the danger of intracranial hemorrhage if one occurs.

Helmets provide meaningful protection during cycling, contact sports, and motorcycling. Seatbelt use — and age-appropriate child car seats — significantly reduces TBI from road traffic collisions. Fall prevention programs for older adults, incorporating home hazard modification, strength and balance training, and regular medication review, address the leading cause of TBI in that population.