Emergency medicine - How to assess and manage head injuries

A normal neurological examination does not reliably indicate the absence of a lesion following head injury. Dr Clare Hammell

Assessment of neurological function includes pupil size and reactivity (Photograph: SPL)
Assessment of neurological function includes pupil size and reactivity (Photograph: SPL)

Each year, an estimated 700,000 people attend hospital as a result of a head injury.1

The wide spectrum of injury coupled with the potential for serious morbidity can make the assessment and management of head-injured patients daunting. This article considers the assessment of patients with head injury and presents some evidence-based advice for their management.

Head injury results from relatively minor and high velocity trauma. Primary brain injury occurs at the time of impact and includes injuries such as subdural and extradural haematomata, cerebral haematoma and contusions and axonal injury.

These insults can evolve resulting in a secondary brain injury, which is exacerbated by exogenous factors, such as hypotension and hypoxaemia.

How should mild head injuries be assessed?
Mild head injury (concussion) occurs following trauma to the head in a patient who has a Glasgow Coma Score (GCS) of 14-15. It encompasses a wide spectrum of injury from those with minimal symptoms to those with significant amnesia or a period of unconsciousness.

The American Academy of Neurology's grading system is useful to stratify such injuries.2 Initial assessment of patients should be performed in a structured manner to ensure coexisting injuries are not missed.

History taking should include a witnessed account of the injury if possible. The following red flag signs and symptoms are markers of a more severe brain injury:

  • Loss of consciousness at any time.
  • GCS <15 on initial assessment.
  • Focal neurological deficit.
  • Retrograde or anterograde amnesia.
  • Persistent headache.
  • Vomiting or seizures post injury.

Previous neurosurgical intervention, use of anticoagulants, clotting disorders or alcohol excess (acute or chronic) increase the likelihood of structural brain injuries after apparently minor trauma and should be specifically enquired about and considered a factor for secondary care referral.

Patients aged 65 years and over have a higher incidence of intracerebral haemorrhage following minor falls (12 per cent in one study3) and so a low threshold for referral and investigation should be adopted in this age group.

Which patients with mild head injury require referral to secondary care?
Normal neurological examination in a patient with a GCS of 15 does not reliably indicate the absence of an intracranial lesion following head injury.4

A subset of patients will req-uire referral to secondary care and CT scanning. Retrospective studies have demonstrated an incidence of acute intracerebral lesions on CT scanning of 6.8-7.5 per cent in patients fulfilling the criteria for a clinical diagnosis of mild head injury.5,6 Independent risk factors were a GCS of 14, loss of consciousness, vomiting and persistent headache.

The amended NICE guidelines (2007) give clear criteria for referral to a hospital emergency department following head injury.7 Many patients may require a period of observation but some will fulfil criteria for CT scanning so referral to a hospital with the appropriate resources to assess and manage them is required.

How should moderate to severe head injuries be assessed?
Moderate and severe head injuries are less common but are associated with a higher rate of intracerebral lesions and extracranial injuries.

Initial assessment should follow a structured approach to ensure that life-threatening injuries are not missed. History taking is frequently limited. In patients at the severe end of the injury spectrum, airway compromise and respiratory depression are common.8

Cardiovascular instability may be the result of hypovolaemia from associated injuries.

Assessment of neurological function in this group should consist of GCS scoring, and pupil size and reactivity. GCS scoring is useful as a tool to monitor deterioration but is poor at predicting outcome following head injury and so should not be used to guide treatment.9

How should patients with moderate to severe head injuries be managed in the pre-hospital environment?
Patients with moderate to severe head injuries meet the criteria for CT scanning and require urgent transfer to a hospital with neurosurgical capabilities.

Pre-hospital management is aimed at reducing the secondary brain injury, which commonly occurs prior to hospital transfer. Maintenance of an adequate airway and support of ventilation should be addressed immediately.

Endotracheal intubation without the administration of sedative and muscle relaxant agents is harmful in this patient group; instead supraglottic airways, such as the laryngeal mask airway, should be used. All patients should receive high flow oxygen. Hypoxaemia and hypotension should be avoided as mortality is increased in severely head injured patients if a single episode of either occurs.8

Hypotension should be assumed to be due to hypovolaemia initially. Evidence for IV fluid management in head-injured patients is poor; hypotension is probably best managed with a small fluid bolus (250-500ml of isotonic crystalloid) while en route to secondary care.

Which patients should have cervical spine immobilisation?
A head injury is the strongest independent risk factor for injury of the cervical spine. Suspect injury and immobilise the cervical spine in all patients with a GCS of <15, neck pain or tenderness, paraesthesiae or focal neurology or in those with a high-risk mechanism of injury.

Ensure rigid cervical collars do not impede cerebral venous blood flow as this can increase intracranial pressure. In combatitive patients it may be safer to leave the cervical spine immobilised.

What are the outcomes following head injury?
Prospective matched studies have demonstrated the presence of post-concussive symptoms (poor memory, fatigue, lack of concentration) up to five years after mild head injuries.10

Outcome following moderate to severe injury is dependent on many variables, such as age and injury characteristics.

  • Dr Hammell is a specialist registrar in anaesthesia and intensive care medicine at the Royal Liverpool Children's Hospital
Stratification of head injuries

American Academy of Neurology three point grading system2

Grade 1 (mild) Transient confusion, symptoms resolve <15
minutes, no loss of consciousness
Grade 2 (moderate) Transient confusion resolving in >15 mins, no
loss of consciousness
Grade 3 (severe) Any loss of consciousness either brief or prolonged

 

Criteria for referral to secondary care7
  • Any loss of consciousness or focal neurological assessment as a result of the injury.
  • GCS <15 on initial assessment.
  • Retrograde or anterograde amnesia.
  • Penetrating head injury or any suspicion of skull fracture.
  • Persistent headache since the injury.
  • Any vomiting or seizures since the injury.
  • High energy head injury.
  • Suspicion of non-accidental injury.

References
1. www.headwayessex.org.uk

2. The American Academy of Neurology www.aan.com

3. Gangavati AS, Kiely DK, Kulchyki AL et al. J Am Geriatr Soc 2009; 57(8): 1470-4.

4. Vilke GM, Chan TC, Guss DA. Am J Emerg Med 2000; 18(2): 159-63.

5. Fabbri A, Servadi F, Marchesini G et al. J neurotrauma 2005; 22(12): 1419-27

6. J Ibanez J, Arikan F, Pedraza S et al. J neurosurg 2004; 100(5): 825-34

7. NICE. Head injury. CG56. London, NICE, 2007. Available from www.nice.org.uk/CG056

8. Trauma; who cares? A report of the National Confidentional Enquiry into Patient Outcome and Death 2007.

9. Matis GK, Birbilis TA. Med Sci Monit 2009; 15(2): 62-5.

10. Akola AS, Muller K,Larsen M et al. Acta Neurol Scand 2007; 115(6): 398-402.

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