Penetrating Mid-facial Injury from a Wooden Branch

An 82-year-old female patient attended A&E after falling into a bush while gardening. She presented with three penetrating branches to the left-hand side of the face (Figure 1). There was no loss of consciousness and the patient remembered the incident entirely.

A medical history was conducted and an urgent CT of the patient's head and face was requested to assess the proximity of the penetrating sticks to vital anatomical structures and to determine the occurrence of intra-cranial injuries (Figure 2). This was in alignment with local health board and NICE guidance given that the patient had a fall and was taking an antiplatelet medication.¹ The CT scan would also indicate whether the sticks were of uniform shape or whether they had branches or had splintered such that withdrawal would cause further trauma.

The CT report showed that the largest wooden stick had a diameter of 6 mm and had penetrated the soft tissues of cheek, with a radiographic 33-mm length. The tip of the stick was adjacent to the anterior border of the masseter muscle. There was soft tissue stranding in subcutaneous fat but no evidence of haematoma. The smaller second stick was superior and lateral to the larger stick and had resulted in skin laceration with a penetrating depth of 10 mm. There was no clinical or radiographic evidence of either stick having caused trauma to any vital structures.

All three sticks were removed (Figure 3) with copious saline irrigation of wounds that were subsequently closed with 4-0 fast-absorbing synthetic sutures under local anaesthetic. The patient was given a booster of tetanus-containing vaccine intramuscularly and broad-spectrum antibiotics were prescribed.

On a follow up appointment 4 days after initial treatment, the wounds were seen to have healed well with no paraesthesia and cranial nerve V and VII function remaining intact.

Discussion

The most common aetiology of penetrating mid-face trauma has been found to be caused by accidental injury.² The mid-face has been defined as the area between the zygomaticofrontal sutures and the maxillary occlusal plane, a region with a high density of musculoskeletal, vascular, and nervous systems.²

Following an ABCDE (Airway, Breathing, Circulation, Disability, Exposure) assessment of the patient, treatment planning focused on evaluating any trauma to the arteries and veins, nerves and muscles in the proximity of the stick penetration (Table 1). Subsequent consideration was then given to wound contamination.

The facial artery is a branch of the external carotid artery and has a critical role in supplying structures of the superficial face (Figure 4). The facial artery courses superiorly across the cheek at an oblique angle towards the oral commissure then ascends along the side of the nose terminating at the medial canthus of the eye.³ A dermal filler injection study proposed a ‘danger line’ where the facial artery is particularly vulnerable to injury and which lies between the oral commissure and the nasal ala regions.⁴ Therein there is high risk of arterial injury approximately 15 mm lateral to the oral commissure at a depth of 11 mm, and 7 mm at the lateral nasal ala at a depth of 12 mm. Assessment of risk of injury is further complicated on account of variations in the structure and path of the facial artery. Lee et al defined three categories according to the patterns of the final arterial branches, and two subcategories within each according to facial artery depth and relationship with the facial musculature layer.⁵ One category of facial artery is described to have an infra-orbital trunk beginning lateral to the oral commissure, running toward the infra-orbital area, superficial to the zygomaticus major and deep to the zygomaticus minor. A subcategory variant exhibits less musculature protection and appears superficial to the zygomaticus major, zygomaticus minor, and levator labii superioris.

The facial vein starts at the medial angle of the eye and runs obliquely behind the facial artery, crosses over the body of the mandible, and drains into the internal jugular vein.⁶ The facial vein has been reported to have a mean lateral distance from the facial artery of 15 mm.⁴

In consideration of this vasculature, it was of particular concern in this case that the penetrating injury from the largest stick appeared midway between the oral commissure and the lateral nasal ala, and was lateral to the nasolabial fold.

The levator labii superioris is a thin, quadrilateral muscle that courses alongside the lateral aspect of the nose and contributes to facial expression and movement of the mouth and upper lip.⁷ Lateral to the levator labii superioris is the levator anguli oris muscle, which raises the corner of the mouth, and zygomaticus minor muscle, which elevates and lateralizes the upper lip while smiling.⁷

The zygomatic and buccal branches of the facial nerve (CN-VII) provide motor innervation to the levator labii superioris and the other midfacial muscles.⁸ These nerves reside at 9.2 ± 2.2 mm and 9.6 ± 2.0 mm from the skin, respectively.⁹ The transverse facial artery has a significant role in lateral face vascularization, and is in close proximity to both the facial nerve zygomatic branch and buccal branch, with vertical distances of 3 mm and 12 mm, respectively.⁵ The maxillary nerve (CN-V2) supplies sensory innervation to much of the mid-facial anatomy. Having passed through the infra-orbital foramen, the maxillary nerve emerges on the face between the levator labii superioris and the levator anguli oris muscles and divides into the palpebral, nasal and superior labial branches.¹⁰ Given the patient exhibited no paraesthesia or paralysis at review, it can be concluded that there was no damage to the facial or maxillary nerves.

The principles of management of soft tissue injuries include the control of bleeding, copious irrigation of the wound, debridement of devitalized tissue, and removal of foreign bodies before closure.¹¹ Irrigation serves to remove foreign material, decrease bacterial contamination of the wound, and to remove cellular debris or exudate from the surface of the wound and is the single greatest intervention in wound care that can reduce the risk of infection.¹² Accordingly, the wounds in this case were irrigated with 1 litre of saline solution. Deeper aspects of the wounds were irrigated using a syringe with a cannula attached. The wounds were debrided to aid uneventful and optimum healing and were assessed to ensure no fragments of dirty contaminants or splinters remained. A sterile surgical scrub brush and nail pick were used for debridement in this case.

The patient's puncture injuries were considered to be tetanus-prone wounds as they had been acquired in a contaminated environment that was likely to contain tetanus spores. Tetanus spores present in soil develop into bacteria, growing anaerobically at the site of the injury, having an incubation period of between 4 and 21 days.¹³Clostridium tetani is an exotoxin-producing pathogen and the sole causative organism for the disease known as tetanus.¹⁴ Tetanus toxin causes muscle stiffness, usually involving the jaw and neck, before becoming generalized and is potentially a fatal condition. Tetanus toxin binds irreversibly to the tissue, and wounds should undergo immediate cleansing and debridement to eradicate spores.¹⁴ Individuals who have received an adequate priming course of tetanus-containing vaccine, but are more than 5–10 years since the last dose, would be expected to make a rapid response to a booster dose of vaccine and therefore it is recommended for all individuals in this group for immediate protection.¹³

When prescribing antimicrobials, prescribers should follow local, where available, or national guidelines on prescribing the shortest effective course, the most appropriate dose and route of administration.¹⁵ A study of traumatic wounds in the emergency department suggests an infection risk assessment is based upon the type of wound, location of the wound, and characteristics of the patient.¹⁶ Antibiotic prophylaxis should be considered in selected cases at high risk of infection, such as puncture wounds, animal/human bites, presence of foreign bodies and exposed fractures. Indeed, a study of penetrating midface trauma identified a significant correlation between antibiotic use and a full recovery free from any deficits.² The patient was prescribed co-amoxiclav 625 mg, three times daily for 7 days, in alignment with the MicroGuide antibiotic prescribing guidelines for the local heath board.

Guidance for post-suture laceration aftercare is opinion based and often varied, particularly regarding the use of petroleum or antibiotic ointments.¹⁷ However, provision of appropriate aftercare advice is imperative to optimum patient outcomes. In alignment with the NICE guidance for postoperative cleansing, the patient was advised to use sterile saline to clean the wound for 2 days post injury, to not dress the wound, and to take antibiotics as prescribed.¹⁸ The use of topical antibiotics promotes bacterial resistance and brings a small risk of allergy.¹⁷ No topical antimicrobial was prescribed in this case owing to the prescription of systemic antimicrobials. The patient was reviewed 4 days post injury to ensure there were no signs of early infection.

Conclusion

This case highlights the potential implications of a facial injury between the oral commissure and nasal ala regions. The management of patients with a penetrating midface injury requires comprehensive anatomical knowledge, an understanding of relevant medical history and an awareness of the current evidence base for the management of head injuries and contaminated soft tissue wounds.