Orbito-Cranial Gunshot Injuries with Retained Sinonasal Bullets

Abstract

Introduction

Gunshot injuries to the sino-orbital region are rare. In South Africa, where gunshot injuries are common, sino-orbital gunshot injuries are encountered. Sino-orbital gunshot injuries are associated with trauma to surrounding facial and intracranial structures. Therefore, the management of these injuries may be complex and often requires an interdisciplinary approach.

Aims

To review the management of orbito-cranial gunshot injuries with retained sinonasal bullets.

Patients and methods

Three cases of orbito-cranial gunshot injuries with retained sinonasal bullets were reviewed. Two cases were complicated by cerebrospinal fluid leaks with ensuing meningitis. The retained bullets in all three cases were successfully removed via a transnasal endoscopic approach.

Conclusion

Sino-orbital gunshot injuries are rare, but may be encountered in areas with high frequencies of gun violence. An associated anterior skull base fracture with CSF rhinorrhoea poses a risk for meningitis and a low threshold for diagnosis and treatment of meningitis should be maintained. Retained bullets in the paranasal sinuses do not pose an immediate risk and may be removed on an elective basis.

Introduction

Epidemiology

Globally, there were more than 250,000 mortalities from firearm-related injuries in 2016, with most deaths per capita in Venezuela and Guatemala. South Africa was ranked 12^th with 6.9 deaths per 100,000 [1].

In the USA, 10% of intentional and 11% of unintentional gunshot wounds occur in the head and neck region [2]. Most of these gunshot injuries are fatal. Only one-third survive and reach the hospital. The majority of these (66%) require admission [2, 3].

Isolated sino-orbital gunshot injuries are uncommon. The exact incidence is not known, and little is reported in the literature. The majority of reported cases occur as a result of suicide attempts or accidental gunshot injury in adolescent males [4].

Ballistics and Pathophysiology

Classification of firearm ballistics is based on the velocity of the projectile. Handguns represent low-velocity firearms with a velocity of less than 300 meters per second. Medium-velocity firearms (300-600 m/s) include submachine guns, and high-velocity firearms (600-1000 m/s) include military assault rifles (AK-47 s and the South African R-4).

The extent of tissue injury is based on the terminal ballistic properties where KE = 1/2mv². KE represents the kinetic energy, m the mass in gram and v the velocity at impact in meters per second. Thus, the extent of the primary tissue injury is principally related to impact velocity.

Bullets produce primary tissue damage in a number of ways:

1. Laceration and crushing forces along the projectile tract

2. Cavitation whereby a temporary cavity is formed by radial stretching around the bullet tract

3. Shock waves which can induce a concussive-like effect in humans, causing acute neurological symptoms.

Management

Initial management should follow the Advanced Trauma Life Support (ATLS) principles. The primary survey is conducted to search for and treat life-threatening injuries. Patients with facial gunshot wounds are at high risk of acute airway compromise and may require endotracheal intubation or a surgical airway.

The initial post-resuscitation Glasgow coma score (GCS) is an important indicator of outcome. Our approach is that, in patients with a GCS of 3-5 following resuscitation, a discussion is had on the merits of treatment or palliative care unless there is a surgically correctable lesion [5]. These patients have a higher mortality and survivors are at risk of a poor functional outcome [5–7].

Active treatment is usually indicated for patients with a GCS equal to or more than 8 [7]. Patients with GCS of 6-7 have their management individualised according to the bullet tract, degree of brain injury, clinical setting and resources, and expected outcome.

The management of these patients also involves the utilization of the Ocular Trauma Classification System [8]. This system subdivides mechanical eye injuries into closed and open globe injuries and is further utilized to provide a description of the type, grade, pupillary response, and zone of globe injuries [9]. The visual acuity at presentation is used in the grading of globe injuries. It spans from Grade 1 (equal or more than 20/40 vision) to Grade 5 (no light perception). A study confirmed the visual acuity to be a strong predictor of final visual outcome. In addition, the study confirmed more unfavourable visual outcomes in patients injured with mines or hand grenades compared to guns [10].

The initial imaging of choice in these patients is non-enhanced computed tomography (CT) due to its ease of access, rapid acquisition, and for its high sensitivity for the detection of acute haemorrhagic lesions [11, 12]. It also provides superior bony anatomy for detection of fractures, indicates the missile path, assists in localization of the retained fragments, and guides planning for possible removal.

Magnetic resonance imaging is not appropriate in the acute assessment of trauma due to the long acquisition time and poor sensitivity for acute bleeding and fractures. An important consideration is the effect of a strong magnetic field on a bullet in vivo. Lead bullets with copper or alloy jackets are safe with respect to MRI-related movement, whereas steel core bullets or pellets exhibit movement in excess of what is considered safe for patients in MRI [13].

CT angiography is performed when a vascular injury is suspected. This includes close proximity of the bullet and tract to the lateral wall of the sphenoid sinus, posterior wall of the maxillary sinus and carotid canal.

Proposed indications for bullet removal, regardless of anatomical subsite, are as follows [14]:

1. Bullets found in joints or the globe of the eye

2. Associated CSF fistula

3. Bullets leading to nerve impingement

4. Bullets lying within a vessel lumen

5. Bullets causing lead poisoning

6. Bullets seen or clinically palpated

7. Medico-legal purposes

Management of these patients should progress according to the urgency of the underlying injuries. Craniocerebral injuries should be managed by Neurosurgery first. In conscious patients with non-urgent intracranial injury, the orbital pathology should initially be managed. In most cases, elective endoscopic removal of the sinonasal foreign bodies is indicated.

The potential complications of a retained bullet in the paranasal sinuses are chronic sinusitis with mucocoele formation, sino-cutaneous fistula, rhinolith formation, meningitis, chronic pain syndrome, and lead poisoning.

Cases of lead poisoning due to retained bullets are well described, and findings include unexplained anaemia, abdominal colic, nephropathy or neurological deterioration [15]. Metallic lead is insoluble, and most patients with retained bullets are not at risk of lead poisoning. Bullets lodged within joint spaces and in pseudocysts are, however, associated with a higher potential risk of poisoning [15]. Retained bullets in contact with cerebrospinal fluid also pose a higher risk for this occurrence [16]. In addition, there has been a documented case of a plasmacytoma arising in the vicinity of a long residing metallic foreign body in the nasal cavity [17].

With regards to access and removal of sinonasal bullets, the following are suggested:

Maxillary Sinus

Bullets in the maxillary sinus are removed via endoscopic antrostomy.

Frontal Sinus

Endoscopic removal of frontal sinus foreign bodies may be performed if the foreign body can be accessed through a Draf 1-3 approach. An external approach can be combined with an endoscopic approach if required for manipulation of the foreign body. In this instance, the following external procedures can be considered: frontal sinus trephination for flushing of the sinus, or a Lynch–Howarth incision for manipulation of a laterally located bullet or for repair of an anticipated CSF leak. A transorbital superior eyelid incision approach can also be considered.

Ethmoid Sinus

A bullet in the ethmoid sinus may be removed by endoscopic ethmoidectomy.

Sphenoid Sinus

Special care should be taken for a bullet in the sphenoid sinus due to the proximity of the optic nerves and internal carotid arteries. If the bullet abuts the lateral wall of the sphenoid sinus, possible injury to the internal carotid artery should be considered and the need for angiography entertained to exclude a false aneurysm. A CSF leak can potentially occur when the bullet is removed, especially if any bony fractures are present and the bullet is adherent to dura.

Patients and Methods

Case 1

A 14-year-old female presented to the emergency department with a single gunshot wound to the left superior eyelid.

Airway and breathing were assessed as normal. There was no active bleeding from the wound; specifically, no epistaxis. The patient was haemodynamically stable. The GCS on presentation was 15, and there was no focal limb weakness. The left pupil was fixed and dilated and had no light perception.

On secondary examination, a 1 cm left periorbital wound and left orbital swelling and proptosis were documented. No other injuries were discovered.

Computed tomography (CT) scan revealed a left frontal sinus entry bullet fracture, traversing the left orbit, orbital apex, and base of skull, with the bullet lodged in the right nasopharynx (Fig. 1). Bullet fragments were present along the tract. There were associated comminuted fractures of the left orbital roof, left nasoethmoid complex, lamina papyracea, and sphenoid sinuses, with associated haemosinus present. A cerebral contusion in the inferior frontal lobe and a small haematoma posterior to the dorsum sellae were also noted.

Fig. 1.

Bullet fragments present along the bullet tract with main bullet fragments lodged in the sphenoid sinus and the right parapharyngeal space

No neurosurgical procedure was required apart from routine neurological observations. Ophthalmology performed a left eye evisceration. The patient had an uneventful post-operative course and was discharged for follow-up to the otorhinolaryngology outpatient department for elective endoscopic removal of the sphenoid sinus bullet fragment.

Two months following discharge she presented with complaints of persistent clear rhinorrhoea and was diagnosed with a cerebrospinal fluid leak. Consequently, an endoscopic repair of a left lateral sphenoid CSF leak was done with simultaneous removal of bullet fragments in the sphenoid floor. Intra-operative findings included a shattered left lateral wall of the sphenoid with an encephalocele. The sphenoid sinus was packed with fat, and this was followed by a cartilage graft to the anterior wall and a septal flap. The post-operative course was complicated by epistaxis; after a period of nasal packing, she was discharged on day 9 following surgery.

Case 2

A 30-year-old male was shot at close range with rubber bullets during civil unrest. He presented to the Emergency Department with injuries to the right eye and right ear. Initial examination revealed no life-threatening injuries. The GCS was 15/15, and there was no focal neurological deficit.

Computed tomography (Fig. 2) revealed retained bullets lodged in the left sphenoid sinus and right posterior nasal cavity, with extension into the right ethmoid air cells. Bullets were also observed in the right petrous bone with an associated fracture. The patient had pneumocranium likely related to this fractured petrous bone. There were right maxillary sinus fractures involving the roof and the medial wall with opacification of the sinus and middle meatus, a right lamina papyracea fracture with opacification of the ethmoid sinuses, and opacification of the right mastoid air cells and middle ear cavity.

Fig. 2.

Computed tomography revealed retained bullets lodged in the left sphenoid sinus and right posterior nasal cavity, with extension into the right ethmoid air cells. Note the frontal pneumocranium

During the hospital admission, the patient developed meningitis secondary to cerebrospinal fluid otorrhoea, which resolved on a course of intravenous antibiotics.

Ophthalmology performed a right eye evisceration. The otolaryngologist performed a canal wall down mastoidectomy for access to remove the foreign bodies and repair a defect in the tegmen tympani.

A second stage surgery was performed to remove bullets from the paranasal sinuses. An endoscopic transnasal transseptal approach was used to access the sphenoid sinus. Two bullets were removed, and no cerebrospinal fluid leak or bleeding was noted intra-operatively. A loose fragment of bone over the internal carotid artery, caused by the gunshot injury, was left in place.

Case 3

A 39-year-old male presented to the Emergency Department with an isolated left eye gunshot injury after he was shot with rubber bullets. The GCS was 15/15, with no associated neurological deficits. On examination of the left eye, the globe was ruptured with no perception of light.

CT scan (Fig. 3) showed severe left facial swelling associated with extensive facial fractures. Two rubber bullets were retained, one lodged in the left sphenoid sinus and the other at the orbital rim. There were burst comminuted fractures of the left orbit medial wall and floor associated with a ruptured left globe, and haemosinus of the left maxillary sinus and the ethmoid sinuses. A left orbital roof fracture was also present and associated with frontal haemosinus, intraparenchymal haemorrhage, and subdural haemorrhage lining the falx cerebri. A computed tomography angiogram was performed which excluded a vascular injury.

Fig. 3.

CT showing two rubber bullets, one lodged in the left sphenoid sinus and the other at the orbital rim

Ophthalmology performed a left eye evisceration and upper lid repair four days following admission.

Three days post-initial surgery otolaryngology performed an examination of the nose under general anaesthesia. A transnasal endoscopic approach was used to retrieve the bullet from the sphenoid sinus. A completely shattered left anterior sphenoid plate was seen with the lateral wall and carotid projections normal and intact. The bullet was retrieved with a curved probe and a Lucs forceps after a partial inferior turbinectomy was done. There was no CSF leak, herniation of brain matter or active bleeding intra-operatively.

No neurosurgical intervention was required, and the patient was discharged on post-operative day 2. On follow-up, three weeks later, the patient reported no rhinorrhoea or epistaxis.

Discussion

Patients with sino-orbital gunshot injuries who present to hospital pose a challenge to attending clinicians, especially those in rural settings, due to the complexity of multidisciplinary care required, as well as the infrequency of this subset of gunshot injuries. Due to the high incidence of gun violence in South Africa and improved access to healthcare, the incidence of these injuries may increase.

Although the injuries to these patients may intimidate first responders and emergency medical staff, the focus should be maintained on standard ATLS principles: securing an airway, stabilizing the patient and referring the patient to a major trauma centre if indicated.

Traumatic brain injury is a major cause of morbidity and mortality in these patients. Full resuscitation and management of the concurrent injuries are indicated in all patients with a GCS of equal or more than 8. Patients with a GCS of less than 8 should have individualised management decisions with Neurosurgery as part of the multi-disciplinary team.

Following initial resuscitation, an unenhanced CT scan of the head is performed as part of the secondary survey. The CT scan, along with the post resuscitation GCS, will guide initial management. When present in the acute setting, traumatic brain injuries are managed by the Neurosurgeon as appropriate, and orbital injuries by the Ophthalmologist. The clinical decision making can be difficult, especially for patients with bihemispheric tracts or those involving the ventricle, where—despite a good initial GCS—the prognosis is poor.

An associated anterior skull base fracture with CSF rhinorrhoea poses a risk for meningitis. These patients require pneumococcal vaccine, ideally with PCV13, on presentation. The patient should be observed for CSF leak and meningitis for 72 hours or until the leak resolves.

Most leaks associated with fractures resolve spontaneously by day 7. Initial conservative management is warranted with later elective removal of the bullet as needed. If a CSF fistula persists, CSF leak repair is performed. An interdisciplinary discussion should ideally determine the best route of repair, with both the Otolaryngology and Neurosurgery teams to make a combined decision on the appropriate surgical approach.

The following summarised guidelines are suggested in patients with a CSF leak following a sino-orbital gunshot injury:

1. Admission for neurological observations. If the patient deteriorates, a repeat CT is warranted and management should be expedited if required [18].

2. A low threshold for the diagnosis and treatment of meningitis should be maintained. The time interval from onset of meningitis to death can be as short as 6 hours.

3. Pneumococcal vaccine should be given at presentation.

4. Prophylactic antibiotics are not routinely indicated in patients with CSF leak.

5. Definitive repair is indicated with leaks persisting for more than 7 days or in the case of meningitis.

Retained bullets in the paranasal sinuses do not pose an immediate risk and may be removed on an elective basis by Otorhinolaryngology. The decision to remove foreign bodies from the paranasal sinuses must be individualised according to each patient’s potential risks and benefits.

On a review of the literature, the decision is usually in favour of removal of foreign bodies of the sinuses, when amenable, due to the sinonasal environment reacting to a foreign body. While in general foreign bodies elsewhere tend to become encapsulated and are sealed off by soft tissue, foreign bodies in the sinuses cause a disruption in the sterile air-soft tissue interface resulting in a greater risk of secondary infection in the long term [19]. Long-term complications of retained bullets include chronic rhinosinusitis and rhinolith formation amongst others.

Historically, foreign bodies from the sinuses were removed via external approaches. With the advent of endoscopic surgery and superior imaging, foreign bodies may be removed more effectively and accurately, with decreased morbidity and acceptable cosmetic outcomes [19]. Removal within 6 months is ideal, and endoscopic surgery can be performed in most cases.

Conclusion

Sino-orbital gunshot injuries are rare, but may be encountered in areas with high frequencies of gun violence. Although sino-orbital gunshot injuries may be intimidating to primary care attending doctors, a focus on ATLS principles needs to be maintained. Unenhanced CT will guide management, and a multidisciplinary approach is required to determine the best route of repair. An associated anterior skull base fracture with CSF rhinorrhoea poses a risk for meningitis and should be managed prophylactically with pneumococcal vaccine; a low threshold for diagnosis and treatment of meningitis should be maintained. Retained bullets in the paranasal sinuses do not pose an immediate risk and may be removed on an elective basis.

Compliance with Ethical Standards

Conflict of interest

All authors declare that they have no conflict of interest.