Head injury

Head injury is trauma to the head that causes brain injury, scalp or skull injury, or both. Most patients have a mild injury, but a small proportion have an intracranial haemorrhage or need neurosurgery. These patients must be identified, secondary brain injury from hypoxia and hypotension prevented, and early transfer arranged.

Clinical relevance. Falls, road collisions, assaults, sports and violence are the main causes. Traumatic brain injury is a leading cause of death and disability in young adults and a major cause in older adults on anticoagulants, who may have bleeds with minimal symptoms.

Pathophysiology. Primary injury occurs at impact (contusion, laceration, diffuse axonal injury, haematoma, fracture). Secondary injury follows hypoxia, hypotension, raised intracranial pressure, seizures, hyperthermia, hyperglycaemia or hypoglycaemia, and abnormal sodium. Cerebral perfusion pressure equals mean arterial pressure minus intracranial pressure, and is kept at 60 to 70 mmHg in severe injury.

Classification by severity (Glasgow Coma Scale).

• Mild: 13 to 15. Moderate: 9 to 12. Severe: 8 or less.
• Concussion (mild traumatic brain injury): transient disturbance of neurological function with normal CT.

Classification by lesion.

• Extradural haematoma (middle meningeal artery; lucid interval, temporal bone fracture).
• Acute subdural haematoma (bridging veins; older adults, alcohol, anticoagulants), chronic subdural haematoma (weeks later).
• Traumatic subarachnoid haemorrhage, intracerebral haemorrhage and contusion, intraventricular haemorrhage.
• Diffuse axonal injury, cerebral oedema and swelling.
• Skull fracture: linear, depressed, basal skull fracture (raccoon eyes, Battle sign, haemotympanum, CSF leak), open fracture, growing skull fracture in children.
• Penetrating injury.

Key distinctions. Deterioration after an initial lucid interval suggests an expanding extradural or subdural haematoma. A unilaterally dilated pupil with falling consciousness indicates herniation. Isolated scalp wounds and minor concussion are common but still need a systematic assessment.

History.

• Mechanism and energy of injury (fall height, road collision speed, pedestrian or cyclist struck, ejection, assault with weapon, penetrating injury), time of injury, and witness account.
• Loss of consciousness, duration of amnesia (before and after impact), confusion, vomiting, headache, seizure, limb weakness, visual disturbance, neck pain, CSF leak from nose or ear.
• Cause of the fall (syncope, seizure, hypoglycaemia, stroke, intoxication, cardiac cause).
• Anticoagulants (warfarin, direct oral anticoagulants, heparin), antiplatelets, bleeding disorders, alcohol, drugs, previous brain surgery or neurological disease, age and frailty.
• In children: developmental level, feeding, irritability, and inconsistent history suggesting non-accidental injury.

Examination.

• Primary survey with cervical spine protection. Exclude hypoxia, hypotension, hypoglycaemia (capillary glucose over 4 mmol/L) and other life threats. Chest, abdomen, pelvis and limbs (head injury is rarely the cause of hypotension in adults).
• Glasgow Coma Scale (eye 1 to 4, verbal 1 to 5, motor 1 to 6) scored by best response, and pupils (size, symmetry, reaction). Repeat at intervals.
• Scalp: haematoma, laceration (palpate with a gloved finger for fracture or depression), boggy swelling. Face and skull base: periorbital and mastoid bruising, haemotympanum, CSF rhinorrhoea or otorrhoea, facial fractures.
• Neurological: focal weakness, speech, cranial nerves, tone, reflexes, plantar responses, gait and cerebellar signs, and vision.
• Neck: tenderness, range of movement, neurological signs (spinal injury is present in up to 5% of severe head injuries).
• Signs of intoxication (do not attribute reduced consciousness to alcohol without exclusion of injury).

Red flags.

• Glasgow Coma Scale under 15 at 2 hours, or any fall of 2 or more points, or confusion that persists.
• Unequal or non-reactive pupils, focal deficit, or seizure after injury.
• Suspected open or depressed skull fracture, or signs of basal skull fracture.
• Vomiting on two or more occasions, severe or worsening headache.
• Age 65 years or more, or anticoagulant treatment, or a known bleeding disorder.
• Dangerous mechanism (fall over 1 metre or 5 stairs, pedestrian or cyclist struck, high speed collision, ejection).
• Amnesia for events over 30 minutes before the impact.
• Cushing response (hypertension, bradycardia, irregular breathing).
• Penetrating injury, CSF leak, or neck injury.
• Intoxication that limits assessment, and suspected non-accidental injury in a child.

Special groups. Older adults can bleed after minor trauma, especially on anticoagulants, with delayed deterioration. Children need weight based doses, validated paediatric decision rules and safeguarding checks. Pregnancy needs left lateral tilt after 20 weeks and obstetric review. Patients with epilepsy or on alcohol need review for withdrawal.

Traumatic intracranial lesions. Extradural haematoma, acute subdural haematoma, chronic subdural haematoma, traumatic subarachnoid haemorrhage, cerebral contusion and intracerebral haematoma, diffuse axonal injury, cerebral oedema, skull fracture (depressed, basal, open), CSF leak, penetrating injury, venous sinus injury, carotid or vertebral artery dissection.

Extracranial and associated injuries. Cervical spine injury, facial fractures, scalp laceration and haematoma, ocular injury, other major trauma (chest, abdomen, pelvis) causing shock.

Causes of reduced consciousness that mimic or accompany injury. Hypoxia, hypotension and haemorrhagic shock, hypoglycaemia, intoxication (alcohol, opioids, sedatives), seizure and post-ictal state, stroke or intracerebral haemorrhage causing the fall, syncope, sepsis, meningitis, hyponatraemia, hypothermia, status epilepticus (including non-convulsive).

Mild injury syndromes. Concussion, post-traumatic headache, post concussion syndrome, vestibular injury and benign positional vertigo, cervical strain.

Paediatric. Non-accidental head injury (abusive head trauma, with retinal haemorrhages and subdural haematoma), birth injury, skull fracture, scalp haematoma.

Step 1. Primary survey and resuscitation. Check glucose, oxygen saturation, blood pressure and pupils. Protect the cervical spine until cleared.

Step 2. Decide who needs a CT head.

• Immediate CT head (within 1 hour) for:
  • Glasgow Coma Scale under 13 at any time, or under 15 at 2 hours after injury
  • suspected open or depressed skull fracture, or any sign of basal skull fracture
  • post-traumatic seizure, focal neurological deficit, or more than one episode of vomiting
  • adults on anticoagulation, with any head injury with loss of consciousness, amnesia, or other risk factor
• Within 8 hours for patients with loss of consciousness or amnesia and age 65 years or more, anticoagulant or bleeding disorder, dangerous mechanism, or amnesia for over 30 minutes before impact. A validated rule for adults with Glasgow Coma Scale 13 to 15 uses these criteria.
• Anticoagulated patients without symptoms need a CT, and a repeat CT or observation for 24 hours is reasonable after a normal initial scan on direct oral anticoagulants or warfarin when risk is high.
• Children: use a validated paediatric rule (Glasgow Coma Scale under 15 at 2 hours, signs of skull fracture, altered mental state, severe mechanism, vomiting, headache, loss of consciousness) with observation as an alternative for intermediate risk, to reduce radiation.
• A blood biomarker (glial fibrillary acidic protein with ubiquitin carboxy-terminal hydrolase L1) taken within 12 hours can rule out intracranial lesions in mild injury where available. A negative result avoids CT, and a positive result needs imaging.

Step 3. CT head without contrast, reviewed urgently. Repeat the CT for neurological deterioration, a fall of 2 or more points in the Glasgow Coma Scale, new focal signs, or after 6 to 12 hours in selected patients with haemorrhage on the first scan.

Step 4. Cervical spine: CT of the cervical spine (in preference to plain films) when Glasgow Coma Scale is under 13, age 65 or over, dangerous mechanism, focal neurological signs, or paraesthesia. Apply a validated clinical decision rule in alert patients (dangerous mechanism, age 65 or over, paraesthesia, inability to rotate the neck 45 degrees to each side, or midline tenderness require imaging).

Step 5. Laboratory tests in moderate and severe injury: full blood count, urea, creatinine, electrolytes (sodium), glucose, coagulation (INR, activated partial thromboplastin time, fibrinogen), anticoagulant level for direct oral anticoagulants, blood gas, lactate, group and crossmatch, alcohol and toxicology, creatine kinase, and pregnancy test.

Step 6. Further imaging: CT angiography for suspected arterial dissection or penetrating injury, MRI for diffuse axonal injury and persistent symptoms with normal CT, and EEG for suspected non-convulsive seizures.

Interpretation. Midline shift, effaced basal cisterns, and haematoma volume (over 30 mL) predict herniation. Extradural haematoma appears biconvex, and subdural haematoma crescentic.

Limitations. CT may be normal in diffuse axonal injury and early haematoma. Clinical decision rules apply to patients with Glasgow Coma Scale 13 to 15 and do not replace judgement for intoxicated, sedated or anticoagulated patients. Observation periods are short in practice, so patients need clear advice.

Immediate priorities (all patients with significant injury).

• Airway with cervical spine protection. Oxygen to keep saturation over 94% (aim for 94 to 98%) and avoid hypoxia (PaO2 under 8 kPa).
• Avoid hypotension: systolic pressure 110 mmHg or more in adults aged 15 to 49 years and over 70 years, and 100 mmHg or more at ages 50 to 69 years, with a target mean arterial pressure of 80 mmHg or more.
• Isotonic saline or blood for volume replacement (avoid hypotonic fluids and glucose containing fluids).
• Control haemorrhage and search for other causes of shock. Keep temperature 36 to 37.5 degrees Celsius, glucose 6 to 10 mmol/L, and sodium 135 to 145 mmol/L.
• Head up 30 degrees (with spinal precautions), neutral neck position, loosened cervical collar, and treat pain and agitation.

Intubation and ventilation. Intubate for Glasgow Coma Scale of 8 or less, a fall of 2 or more points not explained by other causes, airway compromise, hypoxia, seizures, or need for transfer or safe imaging.

Rapid sequence induction with manual in-line stabilisation:

• ketamine 1 to 2 mg/kg IV or etomidate 0.3 mg/kg IV (or propofol 1 to 2 mg/kg in a haemodynamically stable patient)
• plus rocuronium 1.2 mg/kg IV (or suxamethonium 1 to 1.5 mg/kg IV; monitor potassium and avoid in hyperkalaemia, burns and neuromuscular disease)

Give fentanyl 1 to 2 micrograms/kg IV to blunt the pressor response. Avoid hypotension.

Ventilate to PaCO2 4.5 to 5.0 kPa (35 to 38 mmHg) with end tidal CO2 monitoring, and use 4.0 to 4.5 kPa (30 to 34 mmHg) only briefly for signs of herniation.

Raised intracranial pressure or herniation (unequal or dilated pupil, Glasgow Coma Scale fall of 2 or more, extensor posturing, Cushing response).

• Hypertonic saline 3% 150 to 250 mL IV over 10 to 20 minutes (or 2 to 5 mL/kg; can be given peripherally for short use, central line preferred), repeat as needed with sodium measured every 4 to 6 hours (target sodium under 160 mmol/L and rise under 12 mmol/L in 24 hours; monitor chloride and kidney function).
• Or mannitol 20% 0.25 to 1 g/kg IV over 15 to 20 minutes (maximum 1 g/kg for each dose; ensure volume replacement).
• With mannitol, monitor osmolality (stop at over 320 mOsm/kg), kidney function and blood pressure; avoid in hypotension, anuria, and heart failure.
• Sedation and analgesia (propofol 1 to 4 mg/kg/hour, with fentanyl 1 to 3 micrograms/kg/hour, adjusted to blood pressure), head up positioning, avoid jugular compression, normothermia, treat seizures, and urgent neurosurgical review for evacuation of mass lesions or decompressive surgery.
• Do not give corticosteroids, because they increase mortality in traumatic brain injury.

Seizures. Lorazepam 4 mg IV (0.1 mg/kg, maximum 4 mg; repeat once after 10 minutes).

Then levetiracetam 60 mg/kg IV (maximum 4500 mg) over 10 minutes or phenytoin 20 mg/kg IV (maximum 2 g, at not more than 50 mg/minute, with ECG and blood pressure monitoring).

Seizure prophylaxis for 7 days in severe injury or intracranial haemorrhage: levetiracetam 500 to 1000 mg IV or orally every 12 hours (maximum 3 g daily). Reduce the dose in renal impairment: 250 to 750 mg every 12 hours for CrCl 30 to 50 mL/min and 250 to 500 mg every 12 hours for CrCl under 30 mL/min. Monitor mood and behaviour changes and sedation.

Tranexamic acid. For patients with mild to moderate injury (Glasgow Coma Scale 9 to 15) with intracranial haemorrhage on CT, or significant extracranial bleeding, within 3 hours of injury:

• 1 g IV over 10 minutes, followed by 1 g over 8 hours
• reduce when creatinine is over 120 micromol/L; monitor for seizures

Reversal of anticoagulation (intracranial haemorrhage or anticoagulated patient with a positive CT).

• Warfarin or INR over 1.5: 4 factor prothrombin complex concentrate 25 to 50 units/kg IV (dose directed by INR and product label) plus vitamin K 5 to 10 mg IV over 10 minutes; check INR at 30 minutes.
• Dabigatran: idarucizumab 5 g IV (2 doses of 2.5 g within 15 minutes).
• Apixaban or rivaroxaban: andexanet alfa (low dose 400 mg IV bolus then 4 mg/minute for up to 120 minutes for most patients; the high dose schedule depends on the drug, dose and time of the last dose), or 4 factor prothrombin complex concentrate 50 units/kg (maximum 5000 units) when andexanet is not available.
• Heparin: protamine 1 mg for each 100 units given in the previous 2 to 3 hours (maximum 50 mg, slow IV over 10 minutes). Enoxaparin: protamine 1 mg for each 1 mg of enoxaparin given in the last 8 hours (0.5 mg for each 1 mg if 8 to 12 hours; maximum 50 mg).
• Antiplatelet therapy: platelet transfusion has limited benefit and is not routine. Avoid in non-neurosurgical cases. Desmopressin 0.3 micrograms/kg IV over 20 to 30 minutes (maximum 24 micrograms; monitor sodium) has been used.
• Platelets for count under 100 x 10^9/L and fibrinogen replacement for under 1.5 g/L in neurosurgical bleeding.

Open or depressed skull fracture and penetrating injury.

Cefazolin 2 g IV every 8 hours (maximum 6 g daily; for CrCl 10 to 34 mL/min give half the dose every 12 hours), with metronidazole 500 mg IV every 8 hours (maximum 1.5 g daily) for gross contamination or penetrating injury.

Give tetanus cover (vaccine if over 5 years since the last dose, and tetanus immunoglobulin 250 to 500 units IM for incomplete immunisation or high risk wounds). Arrange urgent neurosurgical debridement and elevation of depressed fractures over the thickness of the skull.

Antibiotics are not routinely given for basal skull fracture or CSF leak, and nasal tubes are avoided.

Mild injury (Glasgow Coma Scale 15, normal CT or no CT indicated).

• Observation: half hourly neurological checks until Glasgow Coma Scale is 15, then hourly for 4 hours, then 2 hourly (each check including Glasgow Coma Scale, pupils, limb strength and vital signs), and escalate for any decline.
• Analgesia: paracetamol 1 g orally every 6 hours as needed (maximum 4 g daily; 3 g daily if weight under 50 kg, malnutrition, alcohol excess or liver disease; 15 mg/kg every 4 to 6 hours in children with a maximum of 60 mg/kg daily).
• Avoid NSAIDs for the first 24 hours when haemorrhage is possible, and avoid opioids and sedatives that confuse neurological assessment.
• Antiemetic: ondansetron 4 mg orally or IV every 8 hours as needed (maximum 16 mg for each IV dose; monitor QTc).
• Concussion: physical and mental rest for 24 to 48 hours, then graded return to school, work and sport over days to weeks.
• No return to contact sport until symptom free and after a graduated return, at least 1 week for adults and longer for children. Avoid alcohol, driving and risk activities until recovered.

Moderate and severe injury. Admit to a unit with neurosurgical access, or transfer after resuscitation and imaging (do not delay transfer for further tests). A transfer team with a senior clinician is needed for intubated patients. Continue sedation, ventilation, normal physiology, ICP monitoring when indicated (Glasgow Coma Scale 8 or less with abnormal CT), and treat for secondary injury.

Monitoring. Glasgow Coma Scale, pupils, vital signs and oxygen saturation continuously or hourly, end tidal CO2, glucose, sodium, temperature, urine output, ICP and cerebral perfusion pressure (target 60 to 70 mmHg) when monitored, and repeat CT for deterioration.

Referral and escalation. Neurosurgery for any intracranial haematoma, depressed or open fracture, penetrating injury, CSF leak that persists, Glasgow Coma Scale of 8 or less, or deterioration. Critical care for intubated patients and those with raised ICP. Trauma team for polytrauma. Paediatric and safeguarding teams for children. Neurorehabilitation for moderate and severe injury.

Admission criteria. Glasgow Coma Scale under 15, abnormal CT, ongoing symptoms (vomiting, severe headache, confusion), anticoagulation with positive imaging, suspected skull fracture, CSF leak, intoxication that prevents assessment, social circumstances that prevent safe supervision, and all children with concerns for non-accidental injury.

Discharge and safety netting. Discharge only when Glasgow Coma Scale is 15, symptoms are improving, CT is normal if indicated, and a responsible adult can stay with the patient for 24 hours. Written advice: return for drowsiness, confusion, worsening headache, repeated vomiting, seizure, weakness, speech or visual change, fluid from nose or ear, or neck stiffness. Review at 1 to 2 weeks for persistent symptoms. Anticoagulated patients are reviewed for delayed bleeding with a low threshold for repeat CT.