Subcutaneous facial emphysema secondary to a dental procedure

Abstract

Subcutaneous emphysema is a possible but infrequent consequence of dental procedures. We present the case of a 6-year-old healthy boy transferred from a dental clinic immediately after local anaesthesia for tooth extraction, due to sudden orbital and facial swelling. On physical examination, oedema of the left upper eyelid with fine crepitus on palpation and left hemiface oedema with local pain were observed. Ophthalmologic observation was normal. CT scan of the face and orbits documented extensive infiltration of the subcutaneous tissue planes of the left face by air, with extension to the external part of the body of the mandible, retromaxillary fat, masticatory muscle spaces, parapharyngeal space and adjacent to the orbital roof. After completing initial evaluation, the dentist confirmed the use of an air-driven device during local anaesthesia administration. The patient improved with conservative treatment. Early recognition of this condition is essential to provide an adequate clinical assessment with exclusion of possible life-threatening complications.

Background

Facial subcutaneous emphysema is defined as presence of anomalous air within soft tissue and it is known to be usually caused by head and neck trauma, surgery and infections.¹ Dental procedures are a rare cause of subcutaneous emphysema.² However, subcutaneous emphysema after usage of high-pressure devices, which cause air to be vigorously delivered into surrounding tissues,³ while proceeding dental extractions or repeated Valsava manoeuvres after a dental treatment has already been described.⁴

Subcutaneous emphysema after dental procedures is usually self-limiting and a benign condition.^{1 5} Despite its usual course, serious complications can emerge if the air spreads into deeper spaces causing pneumomediastinum, which can be responsible for other life-threatening conditions such as tracheal compression, pneumopericardium, tension pneumothorax, air embolism and cardiac tamponade.^{5 6} The differential diagnosis of subcutaneous emphysema includes conditions which can present with head and neck swelling, namely angioedema, anaphylaxis, soft tissue infections and traumatic injuries. Therefore, it is important to keep this diagnosis in mind so that we can diagnose this condition rapidly, avoiding serious complications or a misleading diagnosis.

We present the case of a 6-year-old boy who developed sudden orbital and facial oedema after being submitted to a local anaesthesia before dental extraction.

Case presentation

A 6-year-old boy, previously healthy, presented to the paediatric emergency department, transferred from a dental clinic immediately after local anaesthesia, with benzocaine, articaine and epinephrine, for tooth extraction. He had multiple caries and was currently on the last day of a 7-day course of amoxicillin and clavulanic acid for an odontogenic infection in the primary mandibular left first molar. He presented with a sudden orbital and facial oedema on the left hemiface and around the left eye (figures 1 and 2) right after administration of local anaesthesia. He had no fever, respiratory distress, hoarseness or other respiratory or systemic symptoms. On physical examination, he presented afebrile and eupneic with normal vital signs. An oedema of the left upper eyelid was observed with fine crepitus on palpation. The oedema was also present on the left-sided face, with pain on palpation but without other inflammatory signs as erythema or heat. Oropharynx observation revealed multiple dental caries and an inflamed mucosa near the primary mandibular left first molar which presented dental cavity. Ophthalmologic examination revealed normal visual acuity, intraocular pressure and preserved extraocular movements, with no apparent compromise of the optic nerve function. Both anterior and posterior segment findings were found normal on biomicroscopy examination.

Figure 1.

Facial oedema of the left hemiface and left eye eyelids.

Figure 2.

Coronal (A, C) and axial (B) bone window CT images showing extensive infiltration of the subcutaneous tissue planes of the left face by air dissecting from the buccal space (arrow in A), with extension to the canine space (arrow in B), retromaxillary fat, masticatory muscle spaces, parapharyngeal space and adjacent to the orbital roof (arrow in C).

CT scan of the face and orbits documented extensive infiltration of the subcutaneous tissue planes of the left face by air, with extension to the external part of the body of the mandible, retromaxillary fat, masticatory muscle spaces, parapharyngeal space and adjacent to the orbital roof (figure 2). There was no change in the morphology and position of the globe, orbital fat or orbital apex permeability.

After completing initial evaluation, the dentist was contacted and confirmed the use of an air-driven high-pressure device inside the oral cavity during injection of local anaesthetic solution. The air-driven device was intended to distract the patient from injection pain.

Considering the absence of respiratory symptoms and no relevant ophthalmologic findings, the patient was discharged home with recommendation to rest, avoiding physical efforts.

Outcome and follow-up

After 2 days, there was marked reduction of oedema and reduced pain on palpation, with an almost imperceptible crepitus. In the follow-up appointment, 1 week later, a total resolution of the facial oedema was observed, maintaining an unaltered visual assessment. No further investigations were warranted since there was a complete recovery.

Discussion

The differential diagnosis of sudden facial swelling after dental procedures must include allergic reactions, infection and iatrogenic complications, such as subcutaneous emphysema, particularly if there is a history of use of an air-driven high-pressure device.^{7 8} The possibility of an anaphylactic reaction and angioedema must be considered, especially after administration of local anaesthesia (benzocaine, articaine and epinephrine). However, the presence of unilateral facial oedema without respiratory compromise or other typical manifestations (skin rash, pruritus, vomiting, hypotension) is against this diagnosis. The infectious aetiology should also be considered, since there was a previous odontogenic infection for which the patient had been given antibiotics. Nevertheless, the sudden onset of facial oedema was against this possibility, given the fact it has usually a more insidious progression and is accompanied by inflammatory signs, such as heat and redness, which our patient did not present.^{7 9}

Iatrogenic complications such as subcutaneous emphysema may be caused by an air-driven high-pressure device, especially a forward-exhaust one, while administrating local anaesthesia in a friable and inflamed mucosa. This, in turn, comprises a vulnerable point of entry, leading air to enter soft tissues and spread rapidly causing sudden oedema of the affected area. Subcutaneous emphysema is a clinical diagnosis and it is confirmed through the presence of crepitus and tenderness on palpation in the affected region.⁷ It is usually unilateral due to anatomical fascial planes and there are many case reports involving self-limited affected areas, namely only involving periorbital region unilaterally.^{10 11}

This condition is associated, in most cases, to head and neck trauma, surgical procedures, general anaesthesia, infections and dental procedures such as dental extraction.^{4 5} There are many reports in the literature of subcutaneous emphysema as a complication of dental extractions due to the use of air-driven handpieces and air-speed drilling dental instruments, especially if forward exhaust.^{3 8 12} However, to the extent of our knowledge, this is an exceptional case considering that the subcutaneous emphysema occurred after the use of an air-driven device while administrating local anaesthesia to distract from pain and not during the extraction procedure. The air could have entered through the local of injection or through the mucosa, which was inflamed and friable, with loose periodontal sulcus in the primary mandibular left first molar, previously treated with antibiotics for odontogenic infection. The air may have been channelled through the root canal into the buccal space. From there, it may have dissected superiorly into the infraorbital and intraorbital spaces by way of the canine space.

Although the diagnosis can be made clinically, the initial workup of subcutaneous emphysema should include CT imaging of the affected region to confirm the suspicion and to exclude other possible diagnosis and complications.⁵ Chest radiography should also be performed when pneumomediastinum is suspected.¹³ Pneumomediastinum is a rare entity, but in this context, it may develop through extension from the retropharyngeal space which is the main path of communication from oral cavity to the mediastinum.^{8 14} In our case, there was no clinical sign of pneumomediastinum, no evidence of cervical oedema or crepitus and CT scan showed a small amount of air in the parapharyngeal space.

Most cases of subcutaneous facial emphysema are managed conservatively, with bed rest and close observation, consisting in a generally benign and self-limited condition.^{1 3 5} The administration of intravenous antibiotics is questionable and there is no clear evidence that support its use.⁵ Even though there is a potential to micro-organisms from oral flora to migrate to the air invaded spaces, the use of broad-spectrum antibiotics is not well established. Having this fact in consideration and with no signs of an infectious aetiology, our patient did not receive antibiotics. Subsequently, there was no evidence of an infectious complication and complete recovery was observed.

Learning points.

• Early recognition of subcutaneous emphysema secondary to dental procedures is essential to evaluate the possibility of life-threatening complications and therefore give the most appropriate treatment.

• A prompt clinical suspicion and a careful evaluation of signs and symptoms, including a detailed clinical history, are the cornerstones to the diagnosis of subcutaneous emphysema after a dental procedure.

• It is particularly important for dentists and surgeons to have this iatrogenic condition in mind when considering the use of air-driven handpieces, especially those with forward-exhaust mechanism, in any dental procedure, even in benign manoeuvres.

Ethics statements

Patient consent for publication

Parents/guardians consent obtained.