Zygomatic Complex and Nasal Injury

Context

Anyone who has ever worked in an emergency department (ED) on a Friday night knows that facial injuries are a common presentation. In the 15-50 age group, the most common cause of facial fracture is interpersonal violence, at all other ages it is falls [1]. Not surprisingly, males outnumber females for facial fractures by a ratio of 2:1 [2]. Of all facial fractures, nasal fracture is by far the most common seen in the ED [1].

Although emergency medicine (EM) physicians encounter large numbers of patients with facial injuries, interpretation of facial x-rays, particularly injuries involving the zygoma, are a common source of diagnostic error in the ED [3]. While computed tomography is used frequently in trauma, plain x-rays remain relevant in the initial evaluation of potential isolated facial fractures.

Facial x-rays were the most commonly misinterpreted radiographs in one study of EM residents in the USA, leading to the most clinically significant errors from all x-ray misinterpretation [4].

Learning Bite

Although facial injuries are one of the most common problems seen in the ED, interpretation of facial x rays remains a frequent cause of diagnostic error.

Definition

Injuries to the zygoma and the surrounding facial bones are confusingly referred to by a number of different terms including:

• Malar fracture
• Tripod fracture
• Zygomatic complex fracture
• Zygomaticomaxillary complex fracture

All these terms refer to injuries of the zygoma with, in most cases, involvement of the maxilla or temporal bone. The sutures connecting the zygoma to adjacent bones may also be disrupted. Whilst it is important to delineate the individual components of a facial injury, in most instances this can only be done accurately by CT scan at a later stage.

How can we avoid confusion when describing these injuries in the ED?

For clinical clarity in the ED, it is suggested that the majority of injuries involving the zygoma and surrounding bones are either referred to as:

• Zygomatic arch fractures, i.e. fractures predominantly affecting the zygomatic arch, or
• Zygomaticomaxillary complex (ZMC) injuries, i.e. those fractures mainly involving the zygoma, maxilla and/or the orbital rim

Which injuries are not covered by these terms and can be separately identified in the ED?

Other important midface fractures which may be differentiated clinically in the ED are:

• Nasal and nasoethmoidal fractures
• Orbital floor fractures
• Le Fort type fractures

Learning bite

Confusingly, many terms exist for fractures to the zygoma and surrounding bones. For clarity the emergency physician (EP) should refer to injuries either to the zygomatic arch or the zygomaticomaxillary complex (ZMC).

The zygoma forms a large part of the anterolateral wall of the orbit, the lateral margin of the infraorbital rim and the anterior segment of the zygomatic arch. It articulates with the superior portion of the maxilla and the frontal, temporal and sphenoid bones.

In the past the Zygomaticomaxillary Complex (ZMC) was frequently referred to as a tripod but functionally it is more correct to consider it as having four legs , like a four-legged stool. This analogy helps to understand the likely sites of fracture and displacement when the ZMC is struck by a direct blow. The four legs are:

• Lateral orbital rim
• Inferior orbital rim
• Zygomaticomaxillary buttress the thickened area of bone forming the lateral wall of the maxillary sinus
• Zygomatic arch

The ZMC should be considered functionally as a four legged stool as injuries almost always involve more than one, and sometimes all, of the legs.

The zygomatic arch is predominantly formed by the zygomatic process of the temporal bone which articulates with the much smaller temporal process of the zygoma forming the arch. The temporalis muscle and coronoid process of the mandible run lie beneath the arch and may become trapped in depressed fractures of the zygomatic arch.

Immediately below the infraorbital margin of the maxilla lies the infraorbital foramen, through which passes the infraorbital nerve (part of the maxillary division of the trigeminal nerve). The nerves location makes it very vulnerable to both direct injury, and involvement in ZMC fractures.

Fractures

Orbital blow-out fracture

The image illustrates the mechanism of an orbital blow-out fracture. The bony orbit is composed of thickened orbital rims (margins) but relatively thin inner walls. The zygoma and maxilla form the greater part of the medial, inferior and lateral orbital margins as well as almost all of the orbital floor.

ZMC fractures nearly always incorporate some degree of orbital fracture which become clinically relevant to the EM physician when they involve the orbital floor.

In an orbital blow-out fracture, the pressure from a direct blow involving the relatively tough globe is transmitted downwards, fracturing the floor of the orbit, and often results in herniation of intraocular contents into the maxillary sinus.

Learning bite

In blunt injuries involving the eye, the globe is more resistant to perforation than the bony orbit is to fracture.

Nasal bone fracture

The nasal bones are easily fractured due to them being broad and flat, but proximal nasal bone fracture may be accompanied by fractures of adjacent bones which may lead to additional complications such as:

• CSF rhinorrhoea from involvement of the cribriform plate of the ethmoid bone
• Orbital emphysema from fracture of the orbital plate (lamina papyracea) of the ethmoid

Learning bite

Although most nasal fractures are common and relatively benign, involvement of adjacent structures may produce significant complications.

The initial assessment of a patient with a facial injury must start with an ABCDE approach. The airway is of particular concern either from direct injury or from complications of local trauma i.e. bleeding / swelling.

In facial injuries, associated head and neck injury must also be considered. In one study nearly 3% of alert patients with a facial fracture and no neurological deficit had an intracranial haemorrhage on CT scan [5]. Other studies have found up to 10% of patients with a facial fracture, most commonly the nose and ZMC, have an associated significant cervical spine injury 6, [21]. Midface injuries are associated with C5-7 disruption, whilst lower face trauma is more associated with C1-4 disruption.

Learning Bite

The EP must seek to rule out occult head and cervical spine injury in all patients with facial injury. All maxillofacial trauma patients should be considered high risk for cervical spine injuries

History

When taking a history, the EP must include document the mechanism and circumstances of the injury (e.g. interpersonal violence, road traffic accident) as well as the presence or absence of head injury symptoms such as loss of consciousness, amnesia and vomiting.

For injuries of the ZMC and zygomatic arch, the history must also include;

• Visual disturbance indicating possible orbital or globe injury
• Alteration in bite or difficulty moving the jaw suggests mandible, maxilla or zygomatic arch injury
• Sensory disturbance to the cheek and upper gum a sign of infraorbital nerve injury

For nasal injury, the history must include;

• Previous nasal injury / deformity often a perceived nasal deformity is pre-existing.
• Epistaxis this may be extensive with nasal trauma but a history of epistaxis alone is not predictive of a new nasal deformity [7]
• Anticoagulant medication may complicate the management of post-traumatic epistaxis
• Any persistent nasal discharge since the injury this symptom may indicate a nasoethmoid injury with CSF leak.

The EP must also be aware of the association between facial injury and the abuse of children, women and vulnerable adults. If doubt exists, for example a delayed presentation or mismatch between the history and examination findings, then seek advice from a senior EM or paediatric clinician.

Learning Bite

Consider carefully whether the history of injury corresponds with your findings on examination. A second opinion should be sought for any discrepancy found.

Airway and Breathing:

Maxillofacial trauma places the airway at risk [21]. Bleeding, oedema or foreign bodies such as loose teeth may further obstruct the airway. Alcohol intoxication is frequently a factor, with a resultant reduction in consciousness and increased likelihood of vomiting.

Allowing a conscious patient to sit up may help maintain airway patency and reduce the risk of aspiration (only if no spinal injuries are present). A left lateral position may be required if a patient also has suspected spinal injuries and feels like vomiting prior to intubation.

Jaw thrusting or anterior traction on a floating segment of mandible may help open the airway, at the price of possibly increasing haemorrhage.

Endotracheal intubation in this setting is likely to be very difficult, requiring senior input and availability of a difficult airway trolley.

See this RCEM blog for more information:

Circulation:

While maxillofacial haemorrhage can be dramatic, it is only rarely responsible for profound hypotension. Clinicians must look for other causes of blood loss/shock in hypotensive patients [21].

Prompt haemostasis of external bleeding may involve direct pressure, sutures or staples. Internal haemorrhage control may require packing, balloon tamponade, temporary reduction of fractures, or either embolization or surgical ligation of bleeding vessels.

Following haemostasis, most maxillofacial injuries do not require immediate surgical repair.

General Examination

Following a rapid ABCD assessment, a general examination is important to identify any further potential threat to the airway and the systemic effects of bleeding. Some specific points to consider in maxillofacial trauma are outlined below.

Look

Look for the following, remembering to use a head light, nasal speculum and suction when examining the nose:

• Areas of swelling, bruising and bleeding persisting bleeding and/or discharge from the nose may indicate a nasoethmoidal fracture
• Deformity of the nose and zygomatic arch depression of the zygomatic arch (flattened face) is best identified by looking from above or below
• Septal haematoma of the nose a haematoma on the side of the nasal septum which needs draining urgently to prevent a saddle nose deformity from ischaemic necrosis
• Evidence of injury to the eye(s): the position of the eye and visual acuity must be checked. Enophthalmos and proptosis both indicate a significant orbital injury. Features suggesting progressive retrobulbar haemorrhage require an emergency decompression (lateral canthotomy). Any contact lenses must be removed to prevent keratitis.For a more comprehensive account of eye assessment see the Assessment of the eye module.
• Subconjunctival haemorrhage – if the posterior limit of the haemorrhage cannot be seen, it is likely that blood has tracked round the eye from a fracture of the orbital wall. A clear posterior border suggests a direct blunt injury to the globe. The image shows a subconjunctival haemorrhage from an orbital wall fracture with no posterior border visible

Learning bite

Subconjunctival haemorrhage with no visible posterior margin is a useful sign usually indicating orbital wall fracture.

It may be impossible to accurately identify deformity or evidence of eye injury due to marked swelling. If this is the case, arrangements must be made either to re-examine the patient once the swelling has subsided or, if available, to image the eye using ultrasound, CT or MRI scan.

Feel

Learning Bite

Beware children with maxillofacial trauma. An orbital floor (“trapdoor”) fracture can entrap the inferior rectus muscle much more easily than in adults, leading to ischaemia and permanent diplopia. It is a surgical emergency.

A systematic palpation of facial bony landmarks and an assessment of neurological function should be undertaken, specifically:

• Identifying the zygomatic arch check for a step or flattening caused by a depressed fracture
• Identifying the periorbital region for the crepitus of surgical emphysema this indicates a fracture involving a sinus, usually the maxillary
• Intraorally – to assess the maxilla in the upper buccal sulcus for tenderness or a step
• Assessing sensation to the skin supplied by the infraorbital nerve. The image shows cutaneous distribution of the right infraorbital nerve.

Move

Movement of the eye and jaw must be assessed:

• Eye movement, particularly upward gaze, may be restricted in orbital blow-out fractures due to trapping of the herniated inferior rectus muscle
• Limited jaw movement, caused by restricted movement of the coronoid process of the mandible under the zygomatic arch, may be found in depressed fractures of the zygomatic arch. Mandibular fracture may also be a cause see the LZ session Mandibular and Temperomandibular Injury

Facial X rays

X rays are the cornerstone of investigation of ZMC and zygomatic arch injury in the ED. However there is currently no validated decision rule for the ordering of facial x rays. The decision to order an x ray must therefore be based entirely on clinical acumen or locally developed guidelines.

It is important to realise that adequate facial x rays can only be achieved in a co-operative, still patient and provided cervical spine injury has been ruled out. Often Saturday night films taken in intoxicated or uncooperative patients, are of a technically poor quality and should not be used to definitively exclude a fracture. Arrangements should be made for further assessment once the patient is more co-operative.

Having made the decision to order facial imaging, the clinician is then faced with a choice of different views to visualise the ZMC and zygomatic arch including:

• Lateral facial view
• Occipitomental 150 (OM15) and occipitomental 300 (OM30) views
• Submentovertical view

A number of recent studies have looked at whether a single view (either OM15 or OM30) is sufficient to identify a midfacial fracture. A review found that although a single view will save time, cost and radiation, a low sensitivity meant that occasional fractures would be missed [8]. The review suggested that two views should be taken. In a separate study analysing midfacial fractures in 104 patients, the lateral facial view failed to identify a single midface fracture seen in either the OM15 or OM30 view [9]. Therefore, the recommended optimum combination of facial views to maximise pick-up rate and minimise radiation exposure is the OM15 and OM30.

Learning Bite

Two facial views the OM15 and OM30 provide the best combination of accuracy in identifying midfacial fractures whilst minimising radiation exposure.

In patients where clinical findings suggest a zygomatic arch fracture, a specific arch view such as the submentovertical, will facilitate identification of the fracture.

Other Radiological Investigations

When would a spiral facial CT scan be appropriate?

Although it is widely recognised [10] that a spiral facial CT scan is far more accurate at identifying ZMC and zygomatic arch fractures, its use in the ED is restricted to either a second line investigation, usually initiated by the maxillofacial team, or when other injuries (e.g. cervical spine injury) prevent routine facial x-rays being performed.

The facial CT shows an opacified right maxillary sinus.

What methods of investigation could be used to diagnose an orbital blow-out fracture?

The diagnosis of an orbital blow-out fracture may be made on routine facial x-rays (e.g. a teardrop sign) but CT scan remains the gold standard if this injury is suspected or identified. Relatively recently, focused ocular ultrasound (FOUS) has been evaluated in the ED [11,12] and found to be highly accurate in both diagnosing and excluding both orbital and ocular trauma.

The x-ray shows a teardrop sign on the left (arrow) indicating an orbital blow-out fracture.

Are x-rays of the nasal bones necessary?

It is now universally recognised that x-rays of the nasal bones are unnecessary as they do not alter management of the injury. EM doctors attempt to justify them [13] and they are still being performed [14], but they are not warranted for either clinical or medico-legal reasons due to a poor sensitivity and specificity.

Learning bite

There can be no justification for ordering x-rays of the nasal bones for a patient with a suspected nasal fracture.

Biochemical Investigations

In patients with nasal injury and persisting discharge from the nose, it can be difficult to differentiate between nasal secretion and cerebrospinal fluid (CSF) arising from a nasoethmoidal fracture.

Although often advocated, testing for the presence of glucose, which is present in CSF but not normally in nasal secretion, may be falsely positive due to contamination of nasal secretions by blood or tears.

Beta-2 transferrin (also known as the Tau protein) is almost exclusively found in CSF and is a highly sensitive and specific test for the presence of CSF [15].

Learning Bite

The presence of beta-2 transferrin in nasal discharge is the most accurate diagnostic test to confirm CSF rhinorrhoea.

Algorithm for maxillofacial trauma

reference [21]

ZMC Fracture

The vast majority of ZMC fractures can be managed expectantly until local swelling subsides and review by a maxillofacial surgeon at a time guided by local policy.

Any indication of eye involvement (e.g. reduced visual acuity or diplopia) is an indication for urgent referral to a maxillofacial surgeon and / or an ophthalmologist. Suspected infraorbital nerve involvement is not an indication for urgent referral.

Patients should be given general advice regarding their injury including:

• Avoidance of nose blowing as this may produce surgical emphysema.
• Not to occlude the nose when sneezing
• Application of ice packs to the area to reduce swelling
• Take regular analgesia
• General head injury advice

Learning Bite

Patients with a ZMC fracture must be advised to avoid nose blowing or holding the nose when sneezing, as surgical emphysema may result.

There is no good evidence that antibiotics should be routinely prescribed in ZMC fracture, although there is a well documented, but rare, risk of orbital cellulitis [16]. Local policy should be followed.

Zygomatic Arch Fracture

As for ZMC fractures the majority of zygomatic arch fractures do not need urgent surgical intervention. If there is restriction of mouth opening due to trapping of the temporalis muscle or mandibular condyle, is an indication for urgent referral to a maxillofacial surgeon.
Follow-up and advice should follow that of ZMC fracture.

Orbital Blow-out Fracture

Clinical suspicion of an orbital blow-out fracture (e.g. diplopia or reduced eye movements) merits urgent referral to a maxillofacial surgeon. Although plain x ray may reinforce suspicion, facial CT scan will be needed to visualise the fracture in detail and plan surgical repair.

There is no evidence to support routine antibiotic prophylaxis in orbital floor fracture and local guidance should be followed [17].

Learning Bite

Visual disturbance, limitation of eye movements and a teardrop sign on facial x ray are all signs of an orbital blow-out fracture. Immediate referral to an ophthalmologist or maxillofacial surgeon is essential.

Nasal Fracture

Nasal fracture is a clinical diagnosis and there is no evidence that immediate reduction of a displaced fracture, practiced in some centres, is any better than delayed assessment and reduction [18].

However, displaced fractures must be reduced before 14 days as attempted closed reduction beyond this time may be impossible [19].

The following explain the management of specific complications of nasal injury:

Septal haematoma

Septal haematoma is a rare problem but is more common in children due to the relative lack of bone in the nose which is softer, and therefore more easily deformed.

If identified, a patient with a septal haematoma must be referred urgently to an otolaryngologist for drainage and nasal packing.

Traumatic epistaxis

Traumatic epistaxis is common in nasal fracture and, although occasionally severe, is usually self-limiting.
It can be managed in a similar way to a non-traumatic nosebleed – for a more comprehensive account of the management of epistaxis see the session Acute Epistaxis.
If CSF rhinorrhoea is confirmed, the patient should be referred immediately to an otolaryngologist for further assessment.

Learning bite

Uncontrolled epistaxis, CSF rhinorrhoea and septal haematoma are all indications for urgent otolaryngology referral in nasal injury.

Management

The management of nasal injuries varies greatly across the UK [20] and therefore a suggested flow chart is illustrated below:

• Facial injuries are an extremely common ED presentation but diagnostic errors are common when facial x rays are interpreted, particularly for injuries involving the zygoma. (level of evidence 4)
• Although many different terms exist for injuries to the zygoma and surrounding bones, for clarity in the ED the terms zygomaticomaxillary complex (ZMC) or zygomatic arch fracture should be used. (level of evidence 5)
• In addition to injuries involving the midface, the clinician must also consider co-existing head and cervical spine injury. (level of evidence 5)
• Injury to the ZMC, nose or zygomatic arch may be a presentation in child, domestic or vulnerable adult abuse. If doubt exists regarding the history or examination, a senior opinion must be sought. (level of evidence 5)
• The occipitomental 150 and 300 views are the optimal facial x rays to order, maximising the pick-up rate of midface fractures whilst keeping radiation exposure to a minimum. (level of evidence 4)
• There is no justification for ordering x rays of the nasal bones in a patient with a suspected nasal fracture. (level of evidence 5)
• To identify CSF rhinorrhoea, glucose measurement of nasal discharge is prone to error. Identification of beta-2 transferrin in nasal fluid is highly sensitive and specific for the presence of CSF. (level of evidence 4)
• Orbital blow-out fracture must be suspected in a patient with a midface injury where there is visual disturbance, limitation of eye movements or a teardrop sign on facial x ray. Immediate referral is essential. (level of evidence 5)
• Urgent referral to an otolaryngologist is needed in nasal injury where there is a septal haematoma, uncontrolled bleeding or CSF rhinorrhoea. Suspected nasal fractures should otherwise be followed up within 14 days of injury. (level of evidence 5)

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