Head Injury Technical Article

Head injury - this is a technical medical article.

Topics covered:

  • Essentials
  • Epidemiology
  • Basic concepts
  • Early management of the patient with a head injury
  • Management of intracranial complications
  • Follow-up and late complications of head injury
  • Further reading

Essentials

Head injuries cause 1% of all deaths, including 15 to 20% of those in people aged 5 to 35 years, with many survivors facing long-term disability.

Pathophysiology—brain injury may be (1) primary—axonal injury and focal contusions are caused at the moment of impact; or (2) secondary—causes are (a) extracranial—e.g. hypoxia and hypotension, and (b) intracranial—e.g. haematoma, brain swelling, and infection.

Treatment

General aspects—rapid action in the ‘golden hour’ is often essential for success. Life-threatening extracranial injuries that affect the airway, breathing and circulation take priority, and all patients with head injuries should be assumed to have injury to the cervical spine—requiring immobilization—until this can be excluded.

Head injury—deterioration in conscious level, routinely assessed by serial recording of the Glasgow Coma Score (GCS), requires immediate action, with initial management depending on the severity of head injury. (1) Severe (GCS 3–8/15)—immediate referral to a neurosurgical unit is required; elective intubation and ventilation may be required prior to transfer; ventilation should maintain P CO 2 4.0 to 4.5 kPa, and mean arterial pressure should be kept above 90 mmHg; CT scanning may be required. (2) Moderate (GCS 9–13/15)—an urgent CT scan is advisable, with urgent neurosurgical referral (and management as for severe head injury) if this reveals an intracranial abnormality. (3) Mild (GCS 14 or 15)—patients with GCS 15, no history of loss of consciousness, and none of a defined list of criteria for investigation, may be considered for discharge according to local head injury protocols. The availability of CT scanning at all times in centres receiving patients with acute head injury, together with neurological and neurointensive care facilities, is critical for the best outcomes.

Complications, prognosis, and prevention

(1) Acute subdural haematoma—rapid detection and surgical drainage is of proven value. (2) Infection—most neurosurgeons recommend early use of prophylactic antibiotics in penetrating injuries. (3) Cognitive symptoms—85% of adults with severe head injuries remain disabled at 1 year; long-term care requires multidisciplinary support in focused programmes of rehabilitation. Even ‘mild’ injuries can lead to significant ‘postconcussional symptoms’ including headache, dizziness, poor concentration, memory impairment, and personality change.

Prevention—this is a major concern for health and safety legislation, town planning and traffic laws, e.g. compulsory wearing of seat belts and crash helmets.

Epidemiology

It is estimated that each year in the United Kingdom approximately 1 million people attend hospital. Almost one-half of these are children under 16 years of age. Head injuries cause 9 deaths per 100 000 population per year in the United Kingdom. This represents 1% of all deaths, but 15 to 20% of deaths for those aged between 5 and 35 years. As mainly young people are affected, the prevalence of disability caused is very significant, with an estimated 135 000 people in the United Kingdom dependent on care after brain trauma.

In 1986, the Royal College of Surgeons of England published guidelines on the provision of surgical services for patients with head injuries. There were concerns that inappropriate treatment might lead to unnecessary death and disability. This possibility, together with increasing public expectation, led to a further working party that published updated guidelines in 1999. The availability of CT has also increased, so that now it is considered essential for all hospitals that admit patients with head injuries to have CT facilities at all times.

In 2003, the National Institute for Health and Clinical Excellence (NICE) produced comprehensive guidelines on the acute management of head injury. Most hospitals in England and Wales now use these guidelines as the basis of their head injury management protocols.

Basic concepts

Primary and secondary injury

Primary injury is the damage caused to the brain at the moment of impact. It encompasses diffuse axonal injury and focal contusions. Medicine has little to offer for primary injury; prevention, however, is a major concern for health and safety legislation, town planning, and traffic laws (such as the compulsory wearing of seat belts and crash helmets). The focus of medical intervention is the prevention of secondary damage.

The causes of secondary brain damage can be divided into extracranial (hypoxia and hypotension) and intracranial (haematoma, brain swelling, and infection).

Grading the severity of injury

Only 20% of patients are admitted to hospital and most of these are discharged in less than 48 h. About 1 in 500 of the patients attending hospital will develop intracranial haemorrhage. The doctor’s task is to manage patients in such a way that the few with preventable causes of secondary injury are identified and treated effectively.

The British Society of Rehabilitation Medicine defines three broad groups depending on their Glasgow Coma Scale (GCS) score after initial resuscitation:

  • Mild—GCS 13 to 15
  • Moderate—GCS 9 to 12
  • Severe—GCS 3 to 8.

This is a useful categorization for decision-making in head injury management. It should not be confused with other schemes, which are generally retrospective and used for epidemiological and statistical purposes.

The golden hour

Taking into account the practicalities of CT, interhospital transfer, and preparation for theatre, the time available for initial assessment, resuscitation, and treatment of other injuries in the hospital Emergency Department is less than 1 h. This is sometimes referred to as the ‘golden hour’ in which rapid action is critical to the patient’s outcome.

In a typical series of patients who had surgery for acute subdural haematoma, over 70% had a functional recovery (good recovery or moderate disability) if the delay from injury to operation was less than 2 h. If the delay was between 2 and 4 h, just over 60% made a functional recovery. In contrast, for those whose operation was more than 4 h after the injury, less than 10% made a functional recovery.

Such observations led to the Royal College of Surgeons’ guideline stating that evacuation of haematoma, when required, should be done within 4 h. NICE guidelines specified that CT should be performed and assessed within 1 h of the initial request, when indicated. Despite this consensus for rapid assessment and intervention, the realities of resources and interhospital transfer still make this difficult to achieve.

Patients who ‘talk and die’—the importance of deteriorating conscious level

A classic paper, by Jennett and his team, coined the phrase ‘talk and die’ to describe patients whose primary injury was mild, but who succumbed to secondary injury—usually an intracranial haematoma. Deterioration in conscious level is an urgent clinical sign that requires immediate action.

The GCS (Table 1) is now widely used in the United Kingdom and elsewhere, giving objective recording of conscious level, with a high correlation between different observers. Any deterioration is thus more likely to be noticed. When communicating about a patient with head injury, it is good practice to specify observations of each parameter, rather than to use the corresponding numerical scores, which are open to misinterpretation, e.g. a patient scoring 12 based on scores of 4 on eye opening, 3 on verbal response, and 5 on motor response should be communicated as E4, V3, M5. The overall sum should be given and should specify the denominator, to avoid confusion, e.g. 12/15. The most significant parameter in most cases is the motor score. Changes in motor score of even 1 point can reliably indicate that the patient has deteriorated.

Change in consciousness level is the most useful clinical sign in head injury assessment. Generally, a patient with primary brain injury shows a gradually improving conscious level. A patient whose consciousness level deteriorates is very likely to have a secondary brain injury and therefore requires further investigation and treatment. Consciousness level must therefore be assessed at the earliest opportunity, and then reassessed at frequent intervals.

Early management of the patient with a head injury

Extracranial injuries

Life-threatening extracranial injuries always take priority over the head injury. However severe the head trauma, the patient needs to be stabilized for safe transfer. In addition, hypotension and hypoxia are important causes of secondary brain injury. Time-consuming definitive surgery such as the internal fixation of limb fractures should, however, be postponed if possible.

Airway, breathing, and circulation are the first priorities. Management should follow the general recommendations taught in the Advanced Trauma Life Support (ATLS) courses. In particular, assessment should include consideration of respiratory problems, shock, and possible internal injuries.

Table 1 The Glasgow Coma Scale
Motor function
Obeying commands 6
Localizing 5
Flexion 4
Abnormal flexion 3
Extension 2
None 1
Verbal response
Orientated 5
Confused 4
Inappropriate words 3
Incomprehensible 2
None 1
Eye opening
Spontaneous 4
To speech 3
To pain 2
None 1

All patients with head injury should also be assumed to have a cervical spine injury until proven otherwise. Cervical immobilization should be established, unless the patient is fully conscious, cooperative, and able to convince the examining doctor that he or she has no neck pain or tenderness, a full range of cervical movement, and no neurological deficit. There are rare exceptions to this guideline, e.g. a patient with a fixed flexion deformity due to ankylosing spondylitis might present with a cervical fracture; in that circumstance placing the neck in a ‘neutral’ position, in a cervical collar, might actually produce neurological injury.

Initial management of head injuries

After initial assessment, resuscitation, and stabilization of extracranial injuries, the patient is graded for the severity of the head injury. These categories then give a useful broad guide to management.

Severe

If the head injury is severe (GCS 3–8) a member of the team should immediately refer to a neurosurgical unit. If the patient’s best motor response is localization or obeying, then he or she may not necessarily require ventilation, provided that oxygen saturation can be maintained at more than 95%, the P CO 2 at less than 6 kPa, and the P O 2 at more than 12 kPa on 40% inspired oxygen. If the patient’s best motor response is flexion or worse, or if any of the above criteria are not met, then the patient should be electively intubated and ventilated before transfer. Ventilation should be adjusted to maintain the P CO 2 in the range 4.0 to 4.5 kPa. At this stage, the intracranial pressure is unknown, but should be assumed to be high; therefore a mean arterial pressure of at least 90 mmHg should be maintained.

CT scans should be performed according to the NICE guidelines. If the guidelines are followed it should be expected that a relatively high proportion of patients attending the hospital Emergency Department with a head injury will require a CT scan. In most of those cases the scan will need to be done within 1 h.

If, after discussion with the neurosurgical unit, a patient is accepted for transfer, they should be accompanied by personnel able to insert and manage an endotracheal tube and ventilation. The discussion between the two hospitals would include consideration of the risk of transfer, weighed against the benefit that is likely to be achieved. If no specialist intervention is likely, then immediate transfer may not be in the patient’s best interests, especially if there is any haemodynamic instability. There may also be patients whose injuries are so severe that there is little reasonable expectation of survival.

Moderate

If the head injury were moderate (GCS 9–13), an urgent CT scan would be advisable. If the CT scan detects an intracranial abnormality, urgent neurosurgical referral is appropriate and the immediate management is similar to that for severe head injuries given above. If no abnormalities are detected on a CT, care should be taken to exclude metabolic and other causes of reduced conscious level (such as hypoglycaemia or drug overdose). If it appears that diffuse brain injury is the only cause of depressed conscious level, the care of the patient is discussed with the neurosurgical unit. In some cases transfer will be advised, whereas in others observation under the care of the Emergency Department will be appropriate. This will depend on local resources and practices. In either situation, if conscious level remains depressed at 48 h, the patient should be transferred to a neurosurgical unit for further assessment.

Mild

Most head injuries are mild (GCS 14–15). After initial assessment, the next decision is whether further investigation is required.

Patients who have a GCS of 15, no history of loss of consciousness, and none of the criteria for investigation may be considered for discharge according to the local head injury protocol. They must be under the supervision of a responsible adult and written information must be provided concerning symptoms and signs that would warrant seeking further urgent medical advice.

In this context, the criteria for CT scan include:

  • GCS less than 13 at any point since the injury
  • GCS less than 15 at 2 h after the injury
  • Suspected open or depressed skull fracture
  • Any sign of skull base fracture (‘panda eye’ periorbital bruising, cerebrospinal fluid flowing from nose or ear, Battle’s sign, haemotympanum, subconjunctival haemorrhage with no posterior limit)
  • Post-traumatic seizure
  • Focal neurological deficit
  • More than one episode of vomiting
  • Amnesia for more than 30 min of events before the impact

If there has been any loss of consciousness or amnesia, a CT scan should also be immediately requested in patients with any of the following risk factors:

  • Age 65 or older
  • High-energy mechanism of injury, such as a pedestrian hit by a vehicle, an occupant ejected from a vehicle, or a fall from a height greater than 1 m (about five stairs)
  • Anticoagulation or known coagulopathy
  • Significant maxillofacial injuries
  • Difficulty in assessment, whether due to extremes of age (very young or very old) or intoxication.

The validated adult rules on imaging of the head may also be safely used in children and infants, but additional criteria include:

  • Fall from a height greater than the height of the child
  • Tense fontanelle
  • Any suspicion of nonaccidental injury. If nonaccidental injury is suspected in a child then a skull radiograph (as part of a skeletal survey) is also useful, together with other examination such as ophthalmology for retinal haemorrhage.

If the CT scan shows no abnormality, the patient should be admitted for observation until the consciousness level has retuned to normal. Even in those patients with a GCS of 15, they shouldbe admitted if there are other sources of concern to the clinician such as persistent vomiting, severe headache, drug or alcohol intoxication, other injuries, shock, suspected nonaccidental injury, meningism, or leak of cerebrospinal fluid. If the CT scan does show an intracranial abnormality, the care of the patient should be discussed with the neurosurgical unit. In most cases, transfer to the neurosurgical unit is advised.

Management of intracranial complications

Intracranial haematoma

In almost all cases of intracranial haematoma, urgent evacuation is indicated, bearing in mind that, the longer the delay, the greater the risk of death or disability. The above guidelines for CT scan/transfer to neurosurgical unit are all aimed at the earliest diagnosis of the minority of patients with an intracranial haematoma.

The risk of a traumatic intracranial haematoma depends on consciousness level and whether a skull fracture is present (Table 2), although the decision to proceed with CT is no longer based on initial skull radiograph, but instead on the clinical features as specified in the NICE guidelines.

Even in patients with diffuse brain swelling, rather than an intracranial haematoma, neurosurgical intervention may be indicated. Intracranial pressure (ICP) monitoring can be useful in guiding therapy, such as judicious use of inotropes to maintain the cerebral perfusion pressure. In patients who have persistently raised ICP despite optimization of medical management, a decompressive craniectomy can be considered. This intervention is currently the subject of multicentre randomized trials.

Infection

Meningitis and brain abscess can develop after any head injury in which a communication has been made between the environment and the intracranial contents. The most obvious example is a compound depressed fracture, where comminuted bone fragments have been forced inwards, breaching the dura. With some penetrating injuries (such as a fall on to a sharp object or assault with a pointed weapon) the visible wound may be small and appear insignificant. As the injury may have been low velocity, the patient may have a deceptively normal consciousness level. Such patients should always be referred for neurosurgical assessment.

Table 2 The risk of intracranial haematoma
Risk factor Risk of haematoma
No skull fracture
Oriented 1:5983
Not oriented 1:121
Skull fracture
Oriented 1:32
Not oriented 1:4

A closed depressed fracture does not require surgery except for cosmetic reasons if it is on a visible part of the skull.

CSF rhinorrhoea or otorrhoea indicates that a skull base fracture has breached the dura. This places the patient at risk of meningitis while the cerebrospinal fluid leak continues. Ninety per cent of such cases close spontaneously within 2 weeks, and usually neurosurgical intervention is not considered until this time has elapsed. An exception is a fracture of the posterior wall of the frontal sinus, visualized on a CT scan. Such cases should be discussed with the neurosurgeon or the craniofacial team (if one exists locally) with a view to possible early anterior fossa repair.

The use of antibiotics in cerebrospinal fluid leaks is controversial, but a working party reviewing the literature concluded that the available evidence does not support the use of prophylactic antibiotics in patients with cerebrospinal fluid fistulas.

Most neurosurgeons do, however, recommend early use of prophylactic antibiotics in penetrating injuries, and there is some evidence for their use in that context.

Follow-up and late complications of head injury

Cognitive symptoms

After head injury there is a variable period before memory function returns and ongoing memories again begin to be stored. This period is referred to as post-traumatic amnesia and is a useful measure of the severity of brain damage, e.g. when questioned after recovery, a patient may not remember the accident but clearly recall being placed on a stretcher and taken into the ambulance: this would suggest a relatively short post-traumatic amnesia of a few minutes. The post-traumatic amnesia is fixed for a given injury and memories of this period do not later ‘recover’.

It is also common for a patient to lose memory of events immediately before the injury. This is known as retrograde amnesia. Unlike post-traumatic amnesia, the period of retrograde amnesia often progressively reduces as the patient recovers.

Incomplete recovery after a head injury has behavioural, cognitive, emotional, social, and economic effects. For adults with severe head injuries, 85% remained disabled at 1 year following the accident. In the intermediate group, 63% remained disabled at 1 year. Even those with so-called ‘minor’ injuries can face considerable problems: at 3-month follow-up 79% still have headaches, 59% have symptomatic memory impairment, and 34% have not returned to work. In view of this ongoing impairment, patients who have been admitted for more than 48 h following a head injury should be referred for neuroscience involvement in their follow-up.

The most widely used measure of outcome after head injury is the Glasgow Outcome Scale (Table 3). These are broad categories, which miss the subtleties of impairment in many who have had mild injuries, but its wide adoption and recognition make the Glasgow Outcome Scale invaluable for statistical comparisons.

Table 3 The Glasgow Outcome Scale
Good recovery Able to resume preinjury lifestyle
Moderate disability Independent, but unable to resume full preinjury activities
Severe disability Dependent on the care of others for the activities of daily living
Vegetative No sign of psychologically mediated responses
Dead  

Even ‘mild’ injuries, with early brief loss of consciousness and an initial GCS of 14 to 15, can lead to significant symptoms that can interfere with return to previous activities. These ‘postconcussional symptoms’ include headache, dizziness, poor concentration, memory impairment, and personality change. The patient’s relatives often report personality changes, such as ‘bad temper’ and lack of motivation. Such symptoms usually improve over 6 months, especially if the patient and family are warned to expect such problems and reassured that they are eventually likely to resolve.

Rehabilitation after severe head injury requires multidisciplinary input from rehabilitation neurology, physiotherapy, occupational therapy, speech and language therapy, and neuropsychology. Other specialists and therapy services are accessed as appropriate for each individual patient. At least as far as the Glasgow Outcome Scale is concerned, 60% of patients reach their final outcome category by 3 months after the injury. Ninety per cent reach their final score by the end of 6 months.

Epilepsy

Epilepsy is more common if there has been an intracranial haematoma, a depressed skull fracture, or post-traumatic amnesia of more than 24 h. A single seizure, within 1 week the injury, is of less significance than repeated seizures or those occurring after the first week. Any patient who has had a seizure, craniotomy, or depressed skull fracture should be advised not to drive or operate dangerous machinery. They should also contact the Driver and Vehicle Licensing Authority (DVLA).

Chronic subdural haematoma

The initial injury may have seemed very minor and may have occurred many weeks previously. The most common symptom is headache, progressively worsening and eventually accompanied by vomiting. There may also be a focal deficit, which can vary in severity. Increasing intracranial pressure may lead to cognitive impairment and eventually a depressed level of consciousness.

Whatever the pathophysiology, the treatment of choice is evacuation of the subdural collection and irrigation with isotonic saline at body temperature. This is a relatively small operation, which can even be performed under local anaesthetic, so even advanced age and general frailty do not contraindicate its use.

Hydrocephalus

Hydrocephalus occasionally occurs after head injury, particularly if there has been traumatic subarachnoid or intraventricular haemorrhage. It can be distinguished from post-traumatic cerebral atrophy by the appearances on the CT scan: in hydrocephalus, the sulci will be small or effaced relative to the large ventricles and there may be periventricular lucency due to interstitial oedema.

Further reading

 
 
American College of Surgeons Committee on Trauma (1997). Advanced trauma life-support for doctors. Student course manual, 6th edition. American College of Surgeons, Chicago.
 
British Society of Rehabilitation Medicine (1998). Rehabilitation after traumatic brain injury. British Society of Rehabilitation Medicine, London.
 
Commission on the Provision of Surgical Services (1986). Report of the working party on head injuries. Royal College of Surgeons, London.
 
Infection in Neurosurgery Working Party of the British Society for Antimicrobial Chemotherapy (1994). Antimicrobial prophylaxis in neurosurgery and after head injury. Lancet, 344, 1547–51.
 
McMillan T, Greenwood R (1991). Rehabilitation programmes for the brain injured adult: current practice and future options in the UK. A discussion paper for the Department of Health. Department of Health, London.
 
Mendelow AD, Teasdale GM, Jennett B (1983). Risks of intracranial haematoma in head injured adults. BMJ, 287, 1173–6.
 
National Institute for Clinical Excellence (2003). Head injury. Triage, assessment, investigation and early management of head injury in infants, children and adults. 
 
Reilly PL, et al. (1975). Patients with head injury who talk and die. Lancet, ii, 375–7.
 
Rimel RW, et al. (1981). Disability caused by minor injury. Neurosurgery, 9, 221–8. 
 
Seelig JM, et al. (1981). Traumatic acute subdural haematoma. Major mortality reduction in comatose patients treated within 4 h. N Engl J Med, 304, 1511–18. 
 
Teasdale GM (1995). Head injury. J Neurol Neurosurg Psychiatry, 58, 526–39.
 
Working Party on the Management of Patients with Head Injuries (1999). Report of the Working Party on The Management of Patients with Head Injuries. Royal College of Surgeons, London.