Patient-induced progressive facial subcutaneous emphysema masquerading as odontogenic abscess
- 1 Oral and Maxillofacial Surgery, Gold Coast University Hospital, Southport, Queensland, Australia
- 2 School of Medicine and Oral Health, Griffith University, Southport, Queensland, Australia
- 3 Oral and Maxillofacial Surgery, Townsville Hospital and Health Service, Townsville, Queensland, Australia
- Correspondence to Dr Victor Ken On Chang; victor.chang@health.qld.gov.au
Abstract
Facial subcutaneous emphysema (SE) is an uncommon sequelae of dental procedures and often attributed to the use of high-speed air-driven handpieces during surgical extractions, forcing air through fascial spaces. Rarely have there been documented cases of patient-induced SE. In this case report, we present an 18-year-old woman who was referred to the emergency department with a 5-day history of progressive swelling and pain to her right cheek, following a prolonged, but simple extraction of tooth 18. While the dentist and emergency physicians were concerned about an infectious aetiology, history taking, clinical review and imaging corroborated the diagnosis of patient-induced SE secondary to habitual straw use. This report highlights the need for routine postextraction counselling of sinus precautions irrespective of extraction complexity. Additionally, emergency physicians should be aware of SE masquerading as other pathology, including odontogenic abscesses, allergic reactions, angioedema and gas-forming bacterial infections, such as necrotising fasciitis, to ensure appropriate treatment is provided to patients.
Background
Subcutaneous emphysema (SE) is the accumulation or infiltration of air underneath the dermal layer of skin. Strictly speaking, this is confined to the subcutaneous layer, but the term is broadly used to encompass free air in soft tissue spaces, including deeper fascial spaces of the body. Common processes that can lead to SE include trauma (maxillofacial fractures and penetrating injuries to neck and chest), malignancy, anaerobic infections (commonly Clostridium species) and iatrogenic causes (chest tube placement, endotracheal intubation and excessive ventilation).1–3
The documented incidence rate of SE ranges from 0.43% to 2.3% in general surgical and gynaecological procedures.4 However, despite the number of case reports published, SE resulting from general dental procedures is considered a rare phenomenon with no published epidemiological statistics to date.
SE predominantly presents with mild symptoms of discomfort and swelling, which can be managed conservatively. However, air extravasation tracking through fascial planes involving extensive spaces of the neck and chest can lead to pneumomediastinum, pneumopericardium and pneumothorax. If severe, these can be life-threatening with respiratory and cardiovascular collapse.5 6 As such, prompt identification and management to halt the progression is important to prevent these events.
This report presents a seemingly innocuous, but uncommon presentation of patient-induced subcutaneous facial emphysema following a simple extraction of tooth 18. The diagnostic features, differential diagnoses, natural progression, complications and management of SE will be discussed.
Case presentation
An 18-year-old woman presented to the emergency department for review. She was referred by her dentist with 5 days of progressive throbbing pain and swelling to her right cheek with associated trismus after simple extraction of tooth 18 (figure 1). However, the procedure was complicated by small oral aperture, limited access for instrumentation and underlying dental anxiety, resulting in prolonged operative time. The dentist did not require the use of a high-speed air turbine or slow-speed drill for bone removal or tooth sectioning to complete the extraction.
Orthopantomogram pre-extraction showing tooth 18, which would usually be a routine simple dental extraction.
The patient had multiple comorbidities, but of relevance to this case was her newly diagnosed autism spectrum disorder (ASD). While being largely independent and possessing capacity, the patient had repetitive habits characteristic of ASD, including compulsive use of straws for drinking.
On examination, the patient had mild right-sided facial swelling, buccal to the tooth 18 extraction site. There was a palpable firm mass measuring approximately 2×2 cm, which was significantly tender on palpation. Clinically, it was more apparent intraorally just deep to the mucosa and buccinator muscle. Additionally, there was no appreciable crepitus on palpation of the right temporal, malar and buccal regions. There was no asymmetry of the parapharynx and no tenderness over the maxillary sinus. Examination of the tooth 18 extraction socket was unremarkable, with no evidence of discharge. While the patient had trismus to a fingerbreadth, this was increasing with encouragement. She did not have increased respiratory effort and managed her own secretions with normal swallowing.
Investigations
The patient had mildly elevated white cell count of 11×109/L and C reactive protein of 10 mg/L. All other blood tests were largely unremarkable. A CT scan with contrast showed a large 18×18×10 mm mixed gas and fluid locule within the right buccal space (figure 2) with associated smaller air locules in the superficial temporal space (figure 3). There was also mild fat stranding tracking down the investing fascia to the level of C6 spine. Impression from the reporting radiologist was an abscess formation (figure 4). However, this was a very atypical radiological appearance for an abscess due to the predominance of air and the lack of significant fluid level. A decision was made to aspirate the firm, palpable mass with a 21 gauge needle via the buccal mucosa under a local anaesthetic.
Coronal and axial CT views showing a well-defined 18×18×10 mm hypodensity within the buccal space representing a large air locule, indicated by the arrows.
Coronal view CT scan showing small locules of air tracking through fascial spaces. Arrows point to locules tracking through buccal space and into the superficial temporal space.
Coronal view CT scan showing small fluid level associated with large buccal space air locule with some hypoattenuation of the core (indicated by the arrow), appearing as an abscess.
Differential diagnosis
The most likely diagnosis was SE. However, it is important to differentiate this from other causes of facial swelling, which would alter appropriate treatment for the patient. In the postoperative setting, especially with a traumatic extraction, a unilateral swelling to the face can be incorrectly attributed to a haematoma or abscess formation from infection.1 2 7 In previous case reports, subcutaneous and cervicofascial emphysema have also been mistakenly managed as allergic reactions and angioedema but must also be excluded.7 8 An important differential to consider in more extensive SE is necrotising fasciitis as this is a rapidly progressing life-threatening soft tissue infection, which requires extensive surgical debridement.9 Typically, gas-forming bacterial organisms associated with necrotising fasciitis are Clostridum or group A beta-haemolytic Streptococcus.10
The onset and slow progressive nature of this patient’s presentation was inconsistent with an allergic reaction or angioedema. Typically, these would be of acute onset post exposure to an allergen. With an extraction, particularly of a carious tooth, there is always a risk of infection postoperatively. However, our patient appeared clinically well and inflammatory markers were relatively unremarkable, making the differential of odontogenic abscess unlikely. Necrotising fasciitis, which is a more extensive and life-threatening infection, could also be excluded on same grounds. Bedside aspiration of the buccal mass returned air, with no evidence of pus or blood. This further corroborated the clinical impression. The culmination of clinical history, blood tests, radiological appearance and bedside aspiration was consistent with our final diagnosis of SE
Treatment, outcome and follow-up
Needle aspiration with a 21 gauge needle in this instance helped with diagnosis and treatment as it significantly reduced the size of the mass. While there was a small residual mass deep to the buccal mucosa, it was not amenable to further aspiration due to risk of damage to other structures from unguided needle insertion. After aspiration, the patient reported immediate improvement in trismus, achieving a mouth opening of greater than 2.5 fingerbreadth. She also reported decreased throbbing pain at rest and also decreased intensity with mouth opening. The patient was reassured and educated on sinus precautions before being discharged with oral antibiotics (amoxicillin+clavulanate acid) for a week and given instructions to use simple analgesia for pain. At the 1-week follow-up, the patient reported that her swelling had almost completely resolved with return to normal mouth opening. Additionally, she was no longer in pain. A final phone review was conducted 3 weeks post presentation to the emergency department with report of complete resolution.
Discussion
There are numerous documented cases of SE associated with dental procedures. The commonly reported cause is the use of high-speed air-driven handpieces in dental restoration and surgical dental extractions.2 8 11–13 Fewer cases also occurred following endodontic treatment14–16 and subgingival curettage.17 While there are many cases suggesting air-driven devices as instigators of SE, it is important to note that soft tissue emphysema can occur after seemingly innocuous events. In fact, the first ever documented case of SE in 1900 occurred after a musician played a bugle post dental extraction.18 Historically, there have also been cases of self-induced emphysema where individuals would puncture their oral cavity with sharp objects followed by repeated Valsalva manoeuvre.19 20
Patient-induced SE is related to positive pressure activities, such as sneezing, blowing the nose and any activity that simulate the Valsalva manoeuvre.21 However, drinking through a straw, which induces negative pressure may also force air through fascial spaces. The likelihood of SE increases in those with periodontal disease or trauma.22 A breach of the buccal cortex of the tooth 18 socket can be seen on CT (figure 5). Consistent with this case, the prolonged attempt at extraction may have traumatised the periosteum, creating the plane for air entry into the buccal and superficial temporal spaces from our patient’s compulsive drinking through straws. In effect, this may create a trapdoor effect where air can enter the fascial spaces, but is unable to escape.
Coronal and axial CT views in the bony window showing breach of the buccal cortex of the tooth 18 socket, potentially allowing passage of air into fascial spaces.
Patients with facial SE often present with localised tender swelling and palpable crackling or popping, known as crepitus.2 While this is pathognomonic for superficial SE, this may not always be present when deeper fascial spaces are involved. Fascial spaces are potential spaces separated by a thin casing of connective tissue that compartmentalises important structures of the head and neck.23 The roots and sockets of upper molars, particularly the third molars, can sit above the attachment of the buccinator muscle. Extension beyond this muscle would lead to air entry into the buccal space, which also communicates with superficial temporal space. Taking the path of least resistance along pressure gradients and dissecting through cervicofascial planes can then involve the parapharyngeal and retropharyngeal spaces.6 Involvement of such spaces can present clinically as dysphagia, dyspnoea, stridor and dysphonia.2 Extension via the retropharyngeal space into the mediastinum can present as chest or back pain and increasing respiratory distress.24
SE can be seen on plain radiographs. However, the gold standard is CT scan, which allows the visualisation of pockets of air within subcutaneous and fascial spaces as dark or hypoattenuating spots.6 Severe gas-forming bacteria from an infective odontogenic source can also lead to SE.25 However, patients with such infections would be significantly unwell clinically with radiological features of an abscess, usually a well-defined ring-enhancing lesion with low attenuating core. While imaging (figure 4) for this patient showed a small fluid level of the main buccal space gas locule with some hypoattentuation centrally, her clinical status was inconsistent with rapidly progressing deep space infection.
We elected to aspirate in this case as a diagnostic aid because the emergency doctors and radiologists were convinced that it was a collection of pus. Collaterally, this procedure provided symptomatic relief to the patient. Aspiration should be given careful consideration and blind insertion of needle can result in damage to the complex anatomy of the head and neck. It should be reserved for superficial and clearly palpable collections. In the majority of cases, we recommend that patients only need to be reassured of the self-limiting nature of the condition with follow-up for monitoring. The gas or air will eventually resorb into the blood stream for excretion via gas exchange in the lungs, taking approximately 1–2 weeks for complete resolution.13 There is no consensus on whether prophylactic antibiotics should be given. However, majority of reported cases have prescribed prophylactic antibiotics to reduce the risk of secondary infection tracking through the same fascial planes.8 21 In cases related to a dental procedure, antibiotic selection should be broad spectrum to cover common oral pathogens.13 21 Often, penicillin is an adequate first choice for such presentations post dental procedure.26
Dentists should be aware of soft tissue emphysema as a risk even after conducting an extraction in the absence of any handpiece usage for bone removal or section. Therefore, it is advisable to routinely counsel patients on sinus precautions for 2 weeks post extraction. Sinus precautions specifically include instructions to avoid sucking through a straw and any actions that would simulate the Valsalva manoeuvre, such as sneezing with a pinched nose, blowing through a wind instrument and lifting heavy objects. These manoeuvres can force air down pressure gradients into fascial spaces in both the maxillary and mandibular arch. As such, sinus precautions equally apply to post extraction of mandibular dentition in the prevention of SE. SE post dental extraction can also masquerade as various pathologies, including odontogenic abscess, and emergency physicians must be cognisant of this differential to ensure appropriate treatment is provided to patients.
Learning points
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Subcutaneous emphysema, (SE) may occur even after a simple extraction with seemingly innocuous patient-induced causes, such as blowing the nose, sucking through a straw and playing a wind instrument; so it would be reasonable for dentists to provide routine sinus precaution instructions.
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Early recognition of SE is important as dissection through fascial planes can involve deeper spaces of the neck and mediastinum, causing airway and cardiorespiratory collapse.
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Facial SE can masquerade as a number of other pathologies, including odontogenic abscess. Emergency physicians need to be aware of the potential differential diagnoses when reviewing these patients who are often referred to the department by their dentist to provide appropriate management.
Ethics statements
Acknowledgments
Gold Coast University Hospital, Department of Oral and Maxillofacial Surgery.
Footnotes
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Contributors VKOC reviewed and provided clinical care to the patient on the initial presentation. VKOC consented the patient prior to commencement of the write-up. VKOC completed the initial draft of the manuscript. HHT reviewed and provided editions to the manuscript. VKOC and HHT reviewed appropriate imaging to use to illustrate this case. VKOC and HHT reviewed the final manuscript for submission. VKOC gained final written consent from the patient for the final manuscript. VKOC provided revisions of the article after review from editors of the journal.
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Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
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Competing interests None declared.
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Provenance and peer review Not commissioned; externally peer-reviewed.
- © BMJ Publishing Group Limited 2021. No commercial re-use. See rights and permissions. Published by BMJ.
References
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