🧠 TRAUMATIC BRAIN INJURY (TBI) — COMPLETE NOTES

🧩 1. What is Traumatic Brain Injury?

🔹 Definition

A Traumatic Brain Injury (TBI) is:

🔹 What can be damaged?

• Skull (fracture)

• Brain tissue (parenchyma)

• Blood vessels (→ bleeding)

💡 These can happen together depending on severity.

⚡ 2. Types of Injury

🟥 PRIMARY INJURY (Immediate)

• Happens at the moment of trauma

• Caused directly by force (fall, crash, hit)

➡ Includes:

• Brain tissue damage

• Blood vessel rupture

• Skull fracture

❗ Irreversible once it happens

🟧 SECONDARY INJURY (Delayed)

• Happens after the initial injury

• NOT due to more trauma

• Due to cellular + biochemical changes

➡ Develops over:

• Hours → days → weeks → months

🧠 3. AETIOLOGY (CAUSES)

🔹 Mechanical causes:

• Falls

• Motor vehicle accidents

• Sports injuries

• Assaults

• Penetrating injuries (e.g. bullets)

🔹 High-risk groups:

• Elderly (brain shrinkage → vein tearing)

• Athletes (repeated concussions)

• Infants (shaking injuries)

🧠 EPIDURAL HAEMATOMA (EDH)

🟢 1. What is it? (Basic idea)

An epidural haematoma is:
👉 A collection of blood between the skull and the dura mater

• “Epi” = above → so it sits above the dura

• It is usually arterial bleeding → fast and dangerous

🔴 2. Aetiology (Causes)

Most commonly caused by:

• Head trauma

• Temporal bone fracture

• Rupture of the:
  👉 Middle meningeal artery (key exam point)

💡 Why this artery?

• It runs under the skull → easily torn with fractures

🟡 3. Pathogenesis (What’s happening step by step)

1. Trauma → skull fracture (often temporal bone)

2. Middle meningeal artery ruptures

3. Blood rapidly accumulates between:

   • Skull 🦴

   • Dura mater

4. Because it’s arterial bleeding:

   • Blood builds up quickly

5. This creates:
   👉 Increased intracranial pressure (ICP)

6. Brain gets compressed → can lead to:

   • Herniation (life-threatening)

💡 Important:

• Blood cannot cross suture lines → gives classic shape

🧡 4. Clinical Manifestations (Symptoms)

⭐ Classic presentation (VERY IMPORTANT)

👉 Lucid interval

Sequence:

1. Loss of consciousness (immediately after trauma)

2. Patient wakes up (seems fine 😮)

3. Then suddenly deteriorates

Other symptoms:

🧠 Increased ICP:

• Severe headache

• Vomiting

• Confusion

👁 Nerve compression:

• Dilated pupil (same side as bleed)

⚡ Late signs:

• Seizures

• Coma

• Death if untreated

🔵 5. Key Imaging Finding

• CT scan shows:
  👉 Biconvex (lens-shaped) bleed

🚨 6. Why is it dangerous?

• Fast arterial bleed → rapid deterioration

• Neurosurgical emergency

🧠 SUBDURAL HAEMATOMA (SDH)

🟢 1. What is it? (Basic idea)

A subdural haematoma is:
👉 Blood collection between the dura and arachnoid mater

• Usually venous bleeding → slower

🔴 2. Aetiology (Causes)

Main causes:

💥 Trauma

• Especially acceleration-deceleration injuries

👴 High-risk groups:

• Elderly (brain shrinkage stretches veins)

• Alcoholics

• Infants (shaken baby syndrome)

👉 Involves rupture of:
Bridging veins

🟡 3. Pathogenesis (Step by step)

1. Trauma causes brain to move inside skull

2. Bridging veins tear

3. Blood slowly leaks into:

   • Space between dura and arachnoid

4. Because it’s venous bleeding:

   • Slower accumulation

5. Blood spreads over brain surface

💡 Important:

• Can cross suture lines → unlike epidural

🧡 4. Clinical Manifestations

🐢 Slower onset (key difference from EDH)

Symptoms may appear:

• Hours → days → weeks later

Common symptoms:

🧠 Neurological:

• Headache

• Confusion

• Memory problems

• Drowsiness

⚡ Severe cases:

• Weakness (hemiparesis)

• Seizures

• Reduced consciousness

👴 In elderly:

• Personality changes

• Gradual cognitive decline (can mimic dementia)

🔵 5. Types (important)

🔥 Acute SDH

• Severe trauma

• Rapid symptoms

• High mortality

🐢 Chronic SDH

• Mild trauma

• Slow bleed

• Common in elderly

🟣 6. Imaging Finding

• CT scan shows:
  👉 Crescent-shaped bleed

⚖ EPIDURAL vs SUBDURAL — QUICK COMPARISON

🧠 FINAL SIMPLE WAY TO REMEMBER

• Epidural = Emergency + Artery + Fast + Lucid interval

• Subdural = Slow + Veins + Elderly + Crescent