Modern management of head injuries

T. FLANNERY and N. BUXTON*
Department of Neurosurgery, Royal Hospital, Belfast and *Department of Neurosurgery, University Hospital, Nottingham, UK

Introduction

Pathophysiological disturbances

Clinical assessment of the patient

Investigations

Management of head-injured patients

Transfer to a neurosurgical unit

Indications for surgery

Conclusion

References

Management of the head-injured patient is designed to prevent secondary injury and to provide the neurosurgeon with a live patient who has some hope of recovery. This review sets out the background essentials for the nonneurosurgeon dealing with the initial care of a head-injured patient.

Approximately 1 million patients annually attend Accident and Emergency departments with a head injury in the United Kingdom.¹ Head injuries can be classified according to severity. Eighty per cent are mild (Glasgow Coma Scale (GCS) 13-15), 10% moderate (GCS 9-12), the remainder are severe in nature (GCS 3-8).²

Severe head injury accounts for more than 50% of trauma-related deaths, these usually occur following road traffic accidents, assaults and falls.³ This review aims to detail the modern management of head-injured patients in a non-neuro-surgical unit with emphasis on what to do in the absence of on-site neurosurgical expertise, in order to improve patient outcome and to give the surgical trainee sufficient background information for preparation for the surgical diploma of the Royal Colleges.

Head injury can involve the scalp, cranium and/or underlying brain. Scalp injuries include lacerations, contusions and abrasions, depending on the mechanism of injury. Fractures of the skull can involve the vault or base, be simple or compound, depressed or planar. Brain injury can result from the original impact (primary), or can result from the development of secondary complications.^3,4 Primary brain injury can be focal (i.e. intra-cranial haematoma, contusion), and/or diffuse (diffuse axonal injury). Diffuse axonal injury occurs as a result of mechanical shearing following deceleration, causing disruption and tearing of axons.⁵ Intra-cranial haematomas can be extradural, subdural or intracerebral, while contusions may occur adjacent to (coup) or contralateral (contre-coup) to the side of impact. Secondary brain injury occurs when cerebral oedema, ischaemia, infection, tonsillar or tentorial herniation exacerbates the original injury.⁶ The normal autoregulation of cerebral blood flow is lost in a head injury making an injured brain more susceptible to hypo- or hypervolaemia and hypoxia.⁷

The classical Cushing’s Reflex (relative brain ischaemia causing systemic hypertension due to sympathetic outflow activation, so producing bradycardia by feedback from the carotid baroreceptors) is a late event, and often immediately pre-mortem.

Assessment of the head-injured patient begins with the Advanced Trauma Life Support (ATLS) protocol of ensuring patency of the airway with cervical spine control whilst maintaining good oxygenation and tissue perfusion. This aims to prevent the development of secondary brain injury. Of vital importance is the need to treat the casualty as if there is an unstable cervical spine injury before attempting endotracheal intubation, if required. Between 5 and 10% of head injuries have an associated cervical spine injury.⁸ Such an injury can be excluded in almost all cases with a combination of computerised tomography (CT), magnetic resonance imaging (MRI) or flexion-extension radiography of the neck, should clinical suspicion indicate it.^9,10 Once the clinician is satisfied that the patient is resuscitated with a stable cardiorespiratory status, neurological assessment can occur.¹¹ Neurological examination begins with assessment of the patient’s conscious level using the GCS (Table 1).¹² The severity of the head injury can be based on this initial GCS score. A patient with a GCS of 8 or less is in need of urgent anaesthetic assessment as airway compromise and/or reduced lung ventilation is likely. Pupil size and reaction to light are also assessed. Asymmetrical pupil size and reduced reaction to light may indicate brain injury from either diffuse injury or an intra-cranial heamatoma. It may also, however, indicate an isolated injury to the orbit and associated cranial nerves. Asymmetry of limb movement may help in diagnosing an underlying intra-cranial lesion. Observations on the blood pressure, pulse and respiratory rate are also essential, not only to ensure cardiorespiratory stability of the patient, but also to indicate possible brainstem compromise. The mechanism and time of injury, delay in treatment, previous medical history of the patient (e.g. epilepsy, diabetes mellitus) and the presence of alcohol and other drugs that may effect the conscious level are important to ascertain. Exposure of the patient to examine for any other injuries is then made, including a thorough inspection of the patient’s scalp for lacerations, compound fractures and contusions.

All patients with multiple injuries and those with severe head injuries, should have blood samples analysed for baseline estimations - full blood count, electrolytes and urea, coagulation screen, blood gases, alcohol level and blood group (and save). Electrolyte abnormalities and haemoglobin deficiencies should be corrected, if present, whilst clotting disorders should be corrected if surgery is anticipated. With the greater availability of CT, more head-injured patients are being scanned. Skull radiography can be used in the absence of CT scans. But it is by no means comparable as those with head injuries and skull fractures should be considered to have intracranial pathology until proven otherwise.¹³

The ATLS management of head-injured patients depends on the GCS following resuscitation. Patients with a mild head injury (GCS 14-15) should be admitted to a ward where thorough and frequent neurological observations can be ensured.¹³ Should such a patient subsequently deteriorate neurologically (e.g. deteriorating GCS or increasing focal neurological deficit) a CT scan of the patient’s head should be performed promptly, and the local neuro-surgical unit contacted. Patients with a mild head injury should be observed (Table 2) until they make a complete neurological recovery and are only discharged if a responsible adult can supervise them at home for a further few days. All patients with a GCS of 13 or less should receive a CT scan of their head although many authorities would advocate a CT scan on all whose GCS is not normal.^14,15 Those with an acute lesion on CT scan or evidence of diffuse cerebral oedema should be urgently discussed with the local neurosurgical unit, with the CT images transferred immediately, either by computer image-link or courier. All CT scans should be accompanied by a provisional radiology report from the referring hospital. Other indications for neurosurgical referral include compound depressed skull fracture, severely depressed fracture, deteriorating GCS score even with a normal scan and cerebrospinal fluid otorrhoea and rhinorrhoea. The following details are necessary when making a neurosurgical referral: name, age, sex, date, time and mechanism of injury, initial GCS on scene (documented by paramedics) and GCS following resuscitation (before administration of anaesthetic agents should they be required), evidence of deteriorating GCS, pupil reaction, vital observations, previous medical and drug history, previous functional ability and mobility in the case of elderly patients, other injuries and management of the patient since injury.

Transfer of the head-injured patient should be carried out as expeditiously as possible following the guidelines established by the Royal College of Anaesthetists.¹⁵ A patient accepted for transfer to a neurosurgical unit should be accompanied by an anaesthetist, even if not intubated, as neurological deterioration and airway compromise together with hypoventilation may occur in transit. Furthermore, the physical disturbance caused by an ambulance journey and the movement into and out of the ambulance can adversely affect cardiovascular stability in a seriously injured patient. Consequently, it is vitally important to ensure the patient is stable before transfer and monitored appropriately during the transfer. A bolus dose of 1 g/kg of intravenous mannitol (20% solution) over 30 mins may be given to severely head-injured patients to reduce associated cerebral oedema. When combined with frusemide it has a synergistic effect.¹⁶ It can buy time during transfer of a patient with clear signs clinically or on CT, of an expanding intracranial haematoma. Any seizures should be treated with a bolus dose of 15mg/kg of phenytoin administered intravenously over 30 mins with electrocardiographic monitoring. This should then be followed with a daily maintenance dose of phenytoin. The exact destination in the neurosurgical unit should be determined prior to transfer to avoid unnecessary delays in patient treatment. This may be the ward, the intensive care unit or theatre. On arrival, a formal handover to the neurosurgical team, including details of any problems during the transfer (e.g. use of sedation, intubation, cardiorespiratory complications, etc.) with a copy of the CT scans, must be made.

The decision to operate on a head-injured patient is based on a number of factors including premorbid state (previous medical history and functional ability of the patient), the severity of initial injury, the onset and rapidity of neurological deterioration and patient assessment on arrival at the neuro-surgical unit.¹⁷ Important radiological features on CT scan include size of focal lesion(s) together with any associated surrounding oedema and midline shift. Also to be considered, in particular in the case of elderly dependant patients, are the wishes of the relatives. Before embarking on a neurosurgical procedure, it is important to correct any clotting deficiencies and order the required amount of cross-matched blood. With the aid of the CT scans, the operation is then planned in consultation with the consultant neurosurgeon-on-call, and the appropriate theatre staff informed. In exceptional circumstances, neurosurgical intervention, in the form of exploratory burr holes, may be made at the referring hospital. Indications include lack of scanning facilities, inaccessible remote areas, and patients unfit for transfer and, rarely, patients who physically will not fit into the CT scanning machine because of morbid obesity. In these cases, exploratory burr holes may be fashioned in consultation with the nearest neuro-surgical unit. Following the administration of a general anaesthetic, with the patient supine and head positioned in a horeshoe head rest, the scalp is shaved and prepared with povidone-iodine solution and draped. Three separate approximately one inch-long linear incisions are then made. Their orientation should be so as to allow them to be joined up at the neurosurgical unit to produce a formal flap. These can be located one finger breadth anterior to the coronal suture in the pupillary plane (frontal burr hole), one 2.5 cm anterior to the tragus and 2 cm above the zygomatic arch, on the pterion and the other over the parietal bony eminence (parietal burr hole); repeated on the opposite side if no haematoma is found (Figure1). Using a Hudson-Brace drill, with first the perforator to just penetrate the inner table of the skull, and then to extend the opening with the burr, the underlying dura is exposed. An extradural haematoma may be visible and if present can be removed by suction and then lavaged with sterile saline. Any vessels are diathermied with bipolar forceps and the dura is then opened with a number 11 blade in the cruciate fashion. The dural edges are diathermied with bipolar forceps. An underlying subdural haematoma may be visible and can be decompressed with gravity and gentle saline lavage, mindful of the underlying brain. The neuro-surgeon must be informed of the results of such a procedure and the appropriate postoperative care instituted.

Modern management of head injuries at the neurosurgical unit involves continued ventilation, surgery, intensive care unit management of intra-cranial pressure and cerebral perfusion pressure, oxygenation, etc. and is beyond the scope of this article. The aim of all of the above is to minimise any potential for secondary injury and to present the neurosurgeon with a patient who is alive and has a good chance of good quality survival.

Correspondence: Mr N Buxton, Department of Neurosurgery, University Hospital, Nottingham NG7 2UH, UK

EDUCATIONAL SECTION

Modern management of head injuries