Diffuse Axonal Injury (DAI): Causes, Symptoms, and Outcomes

Overview

• DAI results from shearing forces during rotational brain movement.
• Usually occurs after trauma (e.g., sports injuries, car accidents).
• Involves widespread damage to axons, especially in the brainstem and corpus callosum.

Pathophysiology

• Axonal shearing damages tiny neurons:
  • Axons cannot regenerate once injured or severed.
  • Damage leads to disconnection between brain regions.
• Blood vessels may rupture, leading to bleeding.
• Inflammation develops, worsening injury.
• Increased intracranial pressure (ICP) from edema:
  • Swelling restricts blood flow, causing hypoxia and neuronal death.
• Imaging:
  • MRI shows damage.
  • Electron microscopy reveals axonal breaks (post-mortem).

Clinical Features

• More severe than mild concussion.
• Symptoms include:
  • Severe cognitive impairment.
  • Amnesia (short or long-term).
  • Abnormal posturing (decorticate or decerebrate), often temporary.
  • Seizures.
  • Headache.
  • Memory loss.
  • Difficulty concentrating.
  • Irritability, depression, anxiety.
  • Sensitivity to noise and light.
• Long-lasting deficits:
  • Motor, sensory, and cognitive impairments.
  • Increased risk of developing epilepsy.
  • Possible vertigo if inner ear structures are damaged.

Prognosis and Management

• Signs and symptoms can persist weeks to months.
• Monitoring:
  • Glasgow Coma Scale 4-8 indicates severe injury.
  • Inflammation and swelling tend to decrease within 12 hours to days.
  • Imaging and ICP management are critical.
• Recovery:
  • Mild cases may recover fully within days.
  • Severe cases may have permanent deficits.
  • Case-by-case prognosis.
• Long-term effects include neurological deficits, epilepsy, vertigo.

Special Considerations

• Axonal damage typically visualized post-mortem via microscopy.
• Sports players (e.g., hockey) are at high risk.
• Preventive measures focus on reducing trauma and rotational injury.

Summary

• DAI results from brain shearing during rapid rotational forces.
• Severity depends on extent of axonal damage and inflammation.
• Symptoms range from confusion to long-term disability.
• Early detection and ICP control are essential for better outcomes.