Head injury

Causes

  1. Road accident
  2. Assault
  3. Falls
  4. Sporting injuries
  5. Birth trauma

Pathophysiology

Scalp

Skull

Fractures along the lines of stress, not at point of impact. Complications:
  1. bleeding: epidural, subdural
  2. CN palsies: I or VII VIII or III IV VI or II
  3. CSF leakage: rhinorrhoea, otorrhoea, air on radiograph/CT

Brain

Contusion: Coup and contra-coup injury.
Laceration: lesser wing of sphenoid, falx cerebri, tentorium cerebelli
Rotational: diffuse axonal injury (decorticates pt.)
Coma: reticular activating system (tethered below by dentate ligaments but not tethered above)
Autonomic: Motor: decerebrate.

Natural Hx

↑ICP (haemorrhage, cerebral oedema), which is compensated for by:
  1. CSF displaced
  2. Veins compressed
  3. Cushing's reflex (↑systolic BP, bradycardia)
Decompensation:
  1. Transtentorial herniation (CNIII palsy, brain stem functions ↓↓, consciousness↓)
  2. 2°infarction
  3. Venous congestion
  4. CSF accumulation

Treatment

History

Time of injury. Pt's condition. ATLS algorithm. ITU 1/4 h obs. Rate of deterioration: ABG, CXR (CO2 retention).
Then CT head or angiogram under LA or burr holes (min 6).
Cerebral oedema:
  1. elective ventilation therapy,
  2. thiopentone,
  3. ↓T°
  4. surgical decompression
Recovery is hierarchical: brain stem functions recover first. Higher cortical functions recover last (or not at all).
Recovery is exponential: 90% in first year. 90% of that in first 6/12. Tails off at 2 y. Any deficit at 2 y is permanent.
Epilepsy 5% risk: prophylactic anti-convulsants 6/12 to 1 y. If the pt. develops epilepsy then probably anticonvulsants for life.