Brain Injury Causes: Trauma, Stroke, Infection, Toxins, and More

Major Etiologies of Brain Damage

1. Traumatic Brain Injury (TBI)

• Concussion (mild TBI): transient dysfunction; repeated → CTE risk.
• Contusion, diffuse axonal injury, hematoma (epidural, subdural, intracerebral).
• Causes: falls, MVCs, assaults, sports, blast injuries.

2. Stroke (Cerebrovascular Accident)

• Ischemic (87%): thrombus/embolus → infarction.
• Hemorrhagic (13%): intracerebral or subarachnoid hemorrhage.
• Time = brain: IV tPA within 4.5 hrs; thrombectomy up to 24 hrs for large vessel occlusion.

3. Infections

• Meningitis (bacterial, viral, fungal, TB) – meningeal inflammation.
• Encephalitis (HSV, VZV, enteroviruses, arboviruses, autoimmune) – parenchymal inflammation.
• Brain abscess – focal suppurative infection.

4. Neurotoxins

• Heavy metals: lead (developmental neurotoxicity), mercury (Minamata disease), manganese.
• Pesticides: organophosphates (cholinesterase inhibition), paraquat.
• Alcohol (chronic): Wernicke-Korsakoff, cerebellar degeneration.
• Recreational drugs: methamphetamine, cocaine, inhalants.

5. Chronic Systemic Diseases

• Diabetes: microvascular disease → lacunar strokes, cognitive decline.
• Hypertension: white matter lesions, hemorrhagic stroke risk.
• Heart disease: cardioembolic stroke, hypoperfusion.
• Autoimmune: SLE, vasculitis, MS (demyelination).

6. Aging and Lifestyle

• Age-related atrophy, amyloid/tau accumulation (Alzheimer's), vascular contributions.
• Smoking: oxidative stress, vascular damage.
• Physical inactivity: reduced BDNF, cerebral perfusion.

Prevention and Early Intervention

• Helmet use, fall prevention, seat belts.
• Control BP, glucose, lipids; atrial fibrillation anticoagulation.
• Vaccinations (meningococcal, pneumococcal).
• Limit alcohol, avoid toxins.
• Exercise, Mediterranean diet, cognitive engagement, social connection.

Brain health is lifelong; many risks are modifiable.