Emergency management of head injuries

Kevin Turner, Adam Jones, and Ashok Handa give a step by step guide to dealing with patients who have head injuries

Some one million patients present to British hospitals each year with a head injury.¹ The management of this huge patient load falls mainly to accident and emergency departments, and as a senior house officer in casualty you will see many such patients. However, since 20% of those attending with a head injury are admitted, and since most admitted patients are cared for by general or orthopaedic surgeons, many house officers also find themselves participating in the care of these patients. You will need to become skilful in the management of serious head injuries, which, like most emergencies are less daunting than you might think if you keep calm and act in a logical sequence. In many ways minor head injuries are more of a test of your clinical acumen, as difficult decisions have to be made about who to investigate or admit and who to send home.

Skull radiograph, showing a fracture in the centre left of the image (DEPARTMENT OF CLINICAL RADIOLOGY, SALISBURY DISTRICT HOSPITAL/SPL)

Statistics about head injury make salutary reading. Head injuries account for 1% of all deaths, but for 15-20% of deaths in the age group comprising 5-35 year olds.¹ About 50% of traumatic deaths are associated with head injury, and 60% of deaths in road traffic accidents are the result of head injury. The aim in the management of head injury is to limit brain damage. Primary brain injury occurs at the time of the accident when damage results from the sudden distortion of brain tissue within the rigid skull. The damage sustained may be focal (for example, a localised blow to the head) or diffuse (typically occurring in high momentum impacts). Only prevention and protective devices (for example, crash helmets) can reduce primary brain damage.

Your actions could reduce the impact of this primary injury by preventing, identifying, and treating secondary injury to the brain. Secondary brain injury is caused by (1) systemic factors such as hypotension or hypoxia and (2) by compression of brain tissue. Compression is caused by swelling of the brain itself or by haematomas. If this compression is localised then the brain may shift within the fixed dural and bony structures that contain it. For example, the cerebellar tonsils may herniate through the foramen magnum, resulting in "coning," or the medial temporal lobe may herniate beneath the falx, resulting in compression of the oculomotor nerve and resulting in an ipsilateral "blown" pupil (one which is dilated and unresponsive to light).

The Glasgow coma scale (GCS) (see box) is central to the classification, initial management, and ongoing assessment of a patient with head injuries. When measured serially it provides a guide to response to treatment. You need to become familiar with it.

The British Society of Rehabilitation Medicine² has defined the scale of head injuries as:

• Mild (Glasgow coma score 13-15)
• Moderate (9-12)
• Severe (<9)

After moderate head injuries 63% of patients remain disabled one year after their accident and after severe injuries the figure rises to 85%. Surprisingly, minor head injuries also have a poor prognosis with 79% suffering severe headaches, 59% suffering memory problems and 34% unemployed three months after the injury. Only 45% of patients who have suffered a minor head injury are fully recovered a year later.³

Management of unconscious patients with head injury

As in most emergency situations, history taking, examination, and initial management are carried out simultaneously. Remember that nearly 50% of patients with severe head injuries have associated systemic injuries. Do not allow an apparently isolated head injury to divert you from carrying out a full assessment of airway, breathing, and circulation (ABC) of your patient, identifying and treating other life threatening injuries as you go and resuscitating as necessary. Remember that inadequate resuscitation may exacerbate secondary brain injury.

• Call for experienced help.
• Clear the airway (suck out debris and insert an oropharyngeal airway).
• Administer high flow oxygen.
• Apply a rigid cervical collar.
• Your patient needs intubating if his/her gag reflex is reduced or absent (normally anaesthetic responsibility).
• Ensure that breathing is adequate, with bilateral air entry. If not, consider chest trauma as a cause.
• Attach a cardiac monitor and record heart rate, blood pressure, respiratory rate, and temperature.
• Is circulation adequate or is your patient in shock? Hypotension in patients with brain injuries is unlikely to have an intracranial cause. Search for a source of blood loss (chest, abdominal, pelvic).
• Treat hypotension with crystalloids, but be cautious: Too much fluid can exacerbate cerebral oedema. Stop fluids when your patient is normotensive.
• Send blood for crossmatch (and full blood count, urea and electrolytes, and glucose). Check the blood concentrations of glucose with a blood glucose testing stick and give intravenous glucose if it is low.
• Take an arterial blood gas sample.

Beware of both hypercapnia, which causes cerebral vasodilation and increases intracranial pressure, and hypoxia, which may cause ischaemic brain damage. If PaO2 is less than 9 kPa on air or PaCO2 greater than 5.3 then your patient needs ventilating.

Watch out for bradycardia and hypertension. These indicate rising intracranial pressure.

Your patient should now have adequate ventilation and perfusion. You have lessened the risk of systemic factors contributing to secondary brain injury.

Try to obtain some sort of history - ask ambulance crew, witnesses, and relatives. Has the conscious level changed since injury? Remember that if your patient was initially conscious but has now deteriorated then his/her primary brain injury was comparatively slight and secondary factors have intervened. Is there any history of fitting or airway obstruction? What was the mechanism of injury and speed of any impact? Obtain details of medical history and medications.

Record the Glasgow coma score and ensure that it is repeated regularly (every 15 minutes) by nursing staff. Remember that your initial neurological assessment has little value in itself. Its main use is that it provides a baseline to which subsequent scores can be compared. A decrease in the coma score of 2 or more indicates significant deterioration. Conduct a limited neurological examination. Look particularly at pupillary responses - an unequal or dilating pupil indicates rising intracranial pressure. You will be unable to elicit the finer points in a neurological examination - keep your ophthalmoscope in your pocket.

Carefully examine the face and scalp for lacerations, bruising and deformity. Don't forget tetanus prophylaxis.

Look in the ears. A base of skull fracture is indicated by bleeding or leak of cerebrospinal fluid from the ear or by haemotympanum. Other signs of a basal skull fracture are periorbital bruising ("racoon eyes"), bruising around the mastoid (Battle's sign), and leak of cerebrospinal fluid from the nose (rhinorrhoea).

Request some imaging including (1) lateral cervical spine radiographs, (2) chest and pelvic radiographs, (3) skull radiographs. Most patients with a severe head injury will require a computed tomography scan (see below).

If fitting occurs, give intravenous diazepam (normally 5-10 mg in adults).

Restlessness is common. Check that the airway has not become obstructed, that the patient is not in retention, and that unremoved clothing (your patient should have been undressed), plasters, and dressings are not too tight.

Head injury in conscious patients

Less severe head injuries can be just as challenging to manage as severe ones. You must use the history, examination, and investigations to identify the subgroup of patients who require admission.

Take a very careful history. Does your patient recall the whole incident? If there is amnesia is it retrograde (loss of memory of events before the incident) or anterograde (post-traumatic)? The latter is more significant and should be taken seriously. Has there been any loss or alteration of consciousness, vomiting, or seizures? Does your patient complain of visual, hearing or olfactory disturbance? Remember that in elderly patients the cause of their head injury may have been a fall secondary to a cardiac or cerebrovascular event and that this may need investigation and treatment in its own right.

Examine your patient in the same way that you would approach a patient with a more severe head injury. The neurological assessment will clearly be more comprehensive since your patient can assist you in eliciting certain signs.

Be very careful with patients who seem to be intoxicated with alcohol (or drugs). Intoxicated people frequently sustain head injuries. Always consider that a head injury rather than intoxication might be the cause of an altered level of consciousness in this group of patients. If in doubt, admit for observation.

Skull x ray films - who needs them?⁴

The purpose of x radiography is to identify patients at greater risk of intracranial haematomas. For example, a patient with a Glasgow coma score of 15 and no skull fracture has a 1:31 000 chance of having an operable intracranial haematoma. This risk rises to 1:6700 if the patient has a GCS of 15 but has post-traumatic amnesia, and to 1:81 for GCS 15 in the presence of a skull fracture. All patients with the following features in their history or examination should have anteroposterior and lateral skull radiographs taken (unless they fulfil the criteria for computed tomography, in which case skull radiography is redundant): great care must be taken when the half-axial (Towne's) view is taken in patients with suspected cervical injury.

• Impaired consciousness or neurological signs.
• History of loss of consciousness, amnesia, or fits.
• High speed injury or suspected penetrating injury.
• Scalp laceration to bone, large haematoma, or suspected fracture on palpation.
• Persisting vomiting or headache.
• Loss of cerebrospinal fluid or blood from ear or nose.
• Difficulty in assessing the patient (children, drug or alcohol intoxication).

Remember that skull fractures can occur without associated loss of consciousness and conversely that intracranial pathology can be severe even in the absence of a fractured skull. There is even some evidence that production of a fracture may actually lessen brain injury since if bone is fractured less energy is transmitted to the brain itself.

The problem with skull x rays is often not indication but interpretation - not "is an x ray film needed?" but "is this skull x ray film normal?" To compound matters, most are taken when a radiologist is not immediately available. The commonest problem is deciding whether a radiolucent line is a fracture or a normal structure (such as a suture or vascular marking). The frontal (or metopic) suture that divides the frontal bone in two usually fuses by about 3 years of age, but it can persist in adults. Fractures are generally straighter or bend sharply; they usually have parallel edges; they are more radiolucent; they can cross suture lines. Sutures are more windy; they occur in typical places; they are usually symmetrical. Vascular markings are less lucent; less sharply demarcated; may taper as they run distally. Finally, beware depressed skull fractures in which there is an area of double density, representing overlapping bone, opposite a translucent area.

Indications for computed tomography scanning⁴

Most hospitals now have 24 hour access to computed tomography scanning, and in most cases electronic transfer of scans allows viewing by neurosurgeons at distant hospitals.

The following patients should have an immediate scan performed (or be discussed with neurosurgeons if computed tomography scanning is unavailable):

• Persistent coma after resuscitation.
• Deteriorating Glasgow coma score or progressive neurological signs.
• Skull fracture if associated with (1) impaired consciousness, (2) fits, (3) neurological symptoms or signs.
• Open skull fractures (including fractured base of skull).

All patients with abnormal scans should be discussed with a neurosurgical unit.

Who should be admitted?

Patients with severe injuries are usually transferred to neurosurgical units where skull fractures and intracranial haematomas can be expertly managed. Less severely injured patients with the following features in their history or examination should be admitted. Many accident and emergency departments have an associated observation ward, which is ideal:

• Skull fracture.
• Impaired consciousness at the time of assessment or a history of loss of consciousness for more than 5 minutes.
• Persisting neurological symptoms or signs.
• Patients who are difficult to assess - for example, those who are also intoxicated.
• Those with concomitant diseases or medications that pose increased risk (for example, coagulopathies and anticoagulants).

Any patient that you send home should be given an information card on head injury that advises the patient to return if they develop any complications such as vomiting, severe headache, visual disturbance etc. Ensure that they will be in the care of a competent adult.

Children

Head injury is one of the most common reasons for children to attend an accident and emergency department. Children are more likely to have a minor injury, and their injury is more likely to be the result of a fall than anything else. Assessment of children is difficult. The history is often vague, and it can be difficult to establish whether or not there is a history of loss of consciousness for example. Furthermore, the "adult" Glasgow coma score is hard to apply to children, and there are various "paediatric" modifications. Given this difficulty in assessment you should involve your paediatric colleagues. The threshold for skull radiography is lower in children, and the admis- sion rate is comparatively high. Finally, always have in the back of your mind the possibility of non-accidental injury.

Conclusion

Head injuries are very common. When severe they can be distressing to manage but a structured approach will avoid errors. Less severe injuries also require skill if pathology is not to be missed. Finally, don't forget that your record keeping must be beyond reproach - legal claims for compensation following head injuries are common.

Questions

(1) What is the difference between primary and secondary brain injury? What causes secondary brain injury?

(2) The presence of which two cardiovascular signs indicates rising intracranial pressure?

(3) Describe the clinical signs associated with fractured base of skull.

To view the answers, click here

Kevin Turner, research fellow in urology,, Molecular Oncology Group, Institute of Molecular Medicine

John Radcliffe, Hospital, Oxford

Adam Jones, specialist registrar in urology,, Churchill Hospital, Oxford

Ashok Handa, clinical lecturer,, Nuffield Department of Surgery, John Radcliffe Hospital, Oxford


studentBMJ 2000;08:131-174 May ISSN 0966-6494

1. Teasdale GM. Head injury. J Neurol Neurosurg Psych 1995;58:526-39.
2. The British Society of Rehabilitation Medicine.
Rehabilitation after traumatic brain injury. London: British Society of Rehabilitation Medicine, 1998.
3. Royal College of Surgeons of England. Report of the working party on the management of patients with head injuries. London: Royal College of Surgeons of England, 1999.
4. The Society of British Neurological Surgeons. Guidelines for the initial management of head injuries: recommendations form the Society of British Neurological Surgeons. Br J Neurosurg 1998;12(4):349-52.

   

           

Answers

(1) Primary brain injury occurs at the time of the accident. Secondary brain injury is caused by systemic factors (hypotension, hypoxia) or by compression. The impact of the primary injury can be minimised by identifying and treating secondary injury.

(2) Bradycardia and hypertension.

(3) Leak of cerebrospinal fluid from the ear/haemotympanum, periorbital bruising ("raccoon eyes"), perimastoid bruising (Battle's sign), leak of cerebrospinal fluid from the nose (rhinorrhoea).