Key Facts

Head injury is extremely common (~1.4 million ED attendances/year in England). Most are minor, but identifying patients who need CT imaging and neurosurgical intervention is critical.

Epidemiology

~1.4 million head injury presentations to ED annually. ~200,000 admissions/year. Leading cause of death in under-40s. Most common mechanism: Falls (~40-50%), assaults (~20-30%), RTCs (~20%).

Aetiology

• Primary injury: Direct impact → contusion, laceration, diffuse axonal injury, skull fracture
• Secondary injury: Develops hours-days later — cerebral oedema, intracranial haematoma, raised ICP, hypoxia, hypotension
• Prevention of secondary injury is the primary goal of management

Pathophysiology

• Extradural haematoma: Middle meningeal artery (temporal fracture) → blood between skull and dura → rapid expansion → uncal herniation
• Subdural haematoma: Bridging veins torn → blood between dura and arachnoid; acute (high-energy trauma) or chronic (minor trauma in elderly/atrophic brain)
• Diffuse axonal injury: Rotational acceleration → widespread axonal shearing; CT may be normal; poor prognosis
• Raised ICP: Monro-Kellie doctrine — fixed volume skull → increased volume of one component (blood, CSF, brain) must be compensated by reduction in another; when compensation fails → ICP rises → herniation

GCS Assessment

• Eye opening: Spontaneous (4), to voice (3), to pain (2), none (1)
• Verbal: Oriented (5), confused (4), inappropriate words (3), incomprehensible sounds (2), none (1)
• Motor: Obeys commands (6), localises pain (5), withdraws (4), abnormal flexion (3), extension (2), none (1)
• Total: 15 maximum; ≤8 = severe (intubate); 9-12 = moderate; 13-15 = mild

Signs of Basal Skull Fracture

• Battle's sign: Bruising over mastoid (posterior fossa fracture)
• Raccoon eyes: Periorbital bruising (anterior fossa fracture)
• CSF otorrhoea/rhinorrhoea: Clear fluid from ear/nose
• Haemotympanum: Blood behind tympanic membrane
• Cranial nerve palsies: CN VII (facial) most common

Red Flags

• GCS drop ≥2 points — urgent CT
• Lucid interval followed by rapid deterioration — EDH
• Unilateral fixed dilated pupil — uncal herniation
• Cushing's reflex — impending brainstem herniation

CT Head Indications (NICE NG232)

Within 1 hour:

• GCS <13 on initial assessment
• GCS <15 at 2 hours post-injury
• Suspected open or depressed skull fracture
• Signs of basal skull fracture
• Post-traumatic seizure
• Focal neurological deficit

• 1 episode of vomiting

Within 8 hours:

• Loss of consciousness or amnesia + age ≥65
• Loss of consciousness or amnesia + coagulopathy (including anticoagulants)
• Dangerous mechanism (pedestrian vs vehicle, fall >1m, >5 stairs)

Other Investigations

• C-spine CT: If unable to clear clinically (Canadian C-spine rules)
• ABG/VBG: Identify hypoxia, acidosis
• FBC, coagulation: Baseline; correct coagulopathy urgently
• Blood glucose: Exclude hypoglycaemia
• CT angiography: If vascular injury suspected

Initial Management (ABCDE)

• Airway: Intubate if GCS ≤8; avoid nasal adjuncts if basal skull fracture suspected
• Breathing: Aim SpO₂ >96%, PaO₂ >13 kPa, PaCO₂ 4.5-5.0 kPa
• Circulation: Maintain MAP >80 mmHg (cerebral perfusion pressure = MAP − ICP; target CPP >60-70 mmHg)
• Disability: GCS, pupils, glucose
• C-spine: Immobilise until cleared

Raised ICP Management

• Head elevation: 30° with head in midline (optimise venous drainage)
• Osmotherapy: IV mannitol 20% (0.25-1g/kg) or hypertonic saline 3-5%
• Hyperventilation: Only as temporary bridge (target PaCO₂ 4.0-4.5 kPa) — NOT routine
• Sedation: Propofol, midazolam — reduce cerebral metabolic demand
• Decompressive craniectomy: Considered for refractory raised ICP (RESCUEicp trial)

Surgical Intervention

• Extradural haematoma: Craniotomy for evacuation — time-critical emergency
• Acute subdural: Craniotomy if >10mm, midline shift >5mm, or GCS drop
• Chronic subdural: Burr holes and drainage
• Depressed skull fracture: Elevation if depressed > skull thickness or compound

Referral Criteria

• All abnormal CT heads — discuss with neurosurgery
• GCS ≤8 — neurosurgical centre
• Skull fracture, intracranial haemorrhage — neurosurgical opinion

• Mild head injury (GCS 13-15): >95% good outcome
• Extradural haematoma: Excellent prognosis if operated before herniation; mortality <5% if treated early
• Acute subdural haematoma: Mortality ~40-60%; functional outcome often poor
• Diffuse axonal injury: Mortality ~30-40%; survivors often have significant disability
• Chronic subdural: Good prognosis with drainage; recurrence ~10-20%
• Overall head injury mortality: ~1% of all head injuries; ~30% of severe head injuries

NICE CT Head Criteria Summary (NG232)