Orofacial infections - Clerking and Imaging

One of the most frequent calls you will get from A&E is swelling due to dental infection. Depending on the size and location of the swelling, they can pose a direct threat to life. It is not the duty of the OMFS department to act as a primary dental care centre however it is crucial that you are able to identify a concerning swelling and how urgently it requires intervention.
These patients in the past will often have had issues with a particular tooth/teeth but may not have addressed this for various reasons and as a result cultivate a severe infection over time.
There are a number of communicating fascial spaces in the head and neck which we must have an understanding of to determine our investigations and management.

How does a dental abscess develop?

Odontogenic infections arise most commonly due to untreated dental caries or periodontal disease. Often the caries is undetected until it penetrates the dentine and infects the pulp resulting in inflammation and pain. If the infection remains untreated at this stage, the bacteria migrate apically through the root apices and an abscess forms.
As the abscess develops it erodes the buccal cortex (due to its thinner nature) which is demonstrated as a radiolucency on an OPG/periapical radiograph. From here it may spread through the soft tissues and if long standing, you may observe a draining sinus tract.

Figure 1. Formation of a dental abscess [1]

Anatomical cervico-fascial spaces of the head and neck

In general we are more concerned about infections originating from the mandibular teeth however this does not mean to discount spreading infections from the maxillary teeth.
The presence of fascial planes means the infection moves along lines of minimal resistance. Therefore depending on the limits of the planes and positioning of muscles, infections can be redirected or prevented from spreading. Loose connective tissues are broken down in the presence of infections which lead to swelling.
Deep neck space infections are concerning due to the risk of airway compromise. Due to the anatomical boundaries of the neck, infections from the retropharyngeal space and carotid sheath space can spread inferiorly towards the mediastinum.

Figure 2. Cervico-fascial spaces [2]
Figure 3. Spaces of the neck [3]

Examination

Establishing a history is crucial. Look out for other medical issues the patient may present with or underlying conditions such as diabetes, immunosuppression or analgesia overdoses. One of the most common reasons for a paracetamol overdose is dental pain, therefore the patient may be admitted under the medical team to treat this and then get transferred to your ward.
Before you examine the patient intra-orally, ask yourself “Does the patient look well?” It is essential A&E take a set of observations before referring the patient. If the patient has a fever and/or tachycardia it is likely they are systemically unwell and you should request a baseline set of bloods (FBCs, U&Es, CRP).

With regards to the rest of your examination you should be looking for the following things:
1) Location and size of swelling
2) Extensive caries/significantly broken teeth/heavily restored dentition
3) Palpable lymph nodes
4) FOM firm and/or raised? Patient may be drooling if this is the case
5) Presence of purulent discharge intra/extra-orally
6) Does the swelling look cellulitic?
7) Trismus – ideally measure, however if you don’t have a ruler to hand, measure based on how many finger widths you can place between the maxillary and mandibular incisors (normal mouth opening is 35mm).
8) For suspected submandibular swellings, can you feel the lower border of the mandible?
9) Voice changes, difficulty in protruding the tongue. Can indicate more severe infections involving the retropharyngeal/parapharyngeal spaces.

Figure 5. Estimating the degree of trismus [5]
Figure 4. (A) Submandibular and sublingual region. (B) Submandibular region. (C) Cervical region. (D) Palate.
(E) Orbital region. (F) Submandibular and buccal region [4].

Ludwig's angina

“Ludwig's angina is a form of severe diffuse cellulitis that presents acutely and rapidly spreads, bilaterally affecting the submandibular, sublingual and submental spaces, resulting in a state of emergency [6].” This condition poses a significant airway risk therefore it is prudent to involve your seniors early.

Clinical features

1) Bilateral painful swelling of the neck
2) Trismus
3) Bilateral floor of mouth swelling displacing the tongue
4) Pyrexia and elevated WCC and CRP
5) Cellulitis of skin overlying chin and neck
6) Difficulty swallowing

Figure 6. Ludwig’s angina. Note how the sublingual swelling is
giving the appearance of a second tongue [7]

What you need to do immediately

1) Ensure the patient is in a place of safety e.g. resus
2) Contact your registrar/consultant +/- on-call anaesthetist if the patient's airway is in danger
3) Simple measures to ensure patent airway e.g. sit patient upright
4) Ensure you have a cannula in-situ and bloods
5) Consent
6) Put patient on emergency theatre list for EUA, washout, incision and drainage and extraction of teeth as necessary

Orbital Cellulitis

Orbital cellulitis is defined as an infection involving the muscle and fat within the orbit, the globe is not affected. It more commonly occurs in the paediatric population and is usually diagnosed clinically. It is important to be aware of how this condition presents as you may receive referrals from the emergency department querying orbital cellulitis secondary to a dental abscess from a maxillary tooth.
Note orbital cellulitis can be categorised as pre-septal or post-septal and septum in this context refers to the orbital septum. The orbital septum is a thin sheet of fibrous tissue originating from the orbital rim periosteum and blends with the tendon of the levator palpebrae superioris superiorly and inserts into the tarsal plate inferiorly.

Signs and Symptoms

• Ophthalmoplegia
• Proptosis
• Chemosis
• Eyelid erythema
• Periorbital swelling
• Blurred vision
• Fever
• Headaches

Figure 7. Post-septal orbital cellulitis [8]

Special Investigations and Treatment

Special investigations you may consider:
• CT
• MRI
Remember to always consult your trust guidelines with regards to the criteria for imaging paediatric patients.

Without prompt investigation and treatment, the infection can spread to the adjacent tissues leading to complications such as loss of vision, subperiosteal abscess, orbital abscess and intracranial extension of the infection. Broad spectrum antibiotics are usually the mainstay of treatment (check local guidelines).
Within the literature, orbital cellulitis secondary to a dental abscess from a maxillary tooth is relatively uncommon. However, if a patient presents with orbital cellulitis, dental causes should also be investigated if there is no other source of infection. The proposed spread of infection is from an infected maxillary tooth to the maxillary sinus and then to the orbital tissues through defects in the orbital floor/fissures.
The principles of treatment for orbital cellulitis due to a dental infection would be similar to managing a severe dental abscess (removing cause of infection, incision and drainage, antibiotics). If you suspect orbital cellulitis due to a dental infection, notify your registrar.

Infected sebaceous cyst

Sebaceous cysts which become infected will often present in A&E. They tend to present in areas where hair is present. Often these patients will report recurrent swellings and in the past their GP has prescribed antibiotics.
Generally, whatever intervention you may or may not provide, in the emergency setting your job is to alleviate the symptoms. In order to prevent a recurrence, the patient will be booked in to have the cyst, it's lining and contents removed completely.

Clinical features

1) History of recurrence
2) Pus filled swelling
3) Painful, tender lump

Figure 7. Sebaceous cyst presenting to ED [8]

Relevant Investigations

The following investigations should be considered:
1) Observations – Temperature, HR, BP, RR
2) Bloods – FBC, U&Es, CRP. You are looking for signs of a systemic infection so raised WCC and CRP
3) OPG – to determine if the cause of the swelling is odontogenic
4) If you suspect a deeper infection or require clarification regarding what spaces are involved a CT Neck may be indicated. However you must not routinely request a CT scan and the decision to conduct one of these scans must be made by the registrar/consultant.

In terms of what you’re looking for on a CT for example, it is encouraged to have a radiographer report the imaging before you make any clinical decisions based upon it. You’re essentially looking to see if there’s a drainable collection of pus and which space(s) are involved.

Figure 8. OPG - infected LR6, LL6 [9]
Figure 9. CT showing abscess formation within the masseter [10]

Red flags - when to involve a senior

1) Signs of sepsis
2) Compromised airway – contact anaesthetist
3) Ludwig’s angina
4) Necrotising fasciitis
5) Deep neck space infections

General admission criteria

1) Systemically unwell – pyrexia, raised inflammatory markers, tachycardic
2) Trismus
3) Difficulty swallowing, raised floor of mouth, decrease in tongue mobility
4) Increasing swelling after repeat courses of antibiotics
5) Change of voice
6) Deep neck space collection identified
7) Underlying immunosuppression
8) Submandibular/sublingual space abscess +/- other space involvement
The decision you have to make with your senior is, can this infection be incised and drained under LA and the patient sent home on oral antibiotics? If so, the patient does not require admission.
However, if the swelling needs to be incised under GA and/or a deep space infection requiring drainage, the patient will require admission. General rule of thumb is for submandibular, sublingual and deep neck space swellings due to infections/collection of pus, the patient will be admitted for formal I&D under GA.

What to do when admitting a patient

1) Bloods – FBCs, U&Es, CRP and insert a cannula
2) Imaging (OPG +/- CT)
3) IV Abx – usually 1.2g co-amoxiclav TDS (if the patient is not allergic to coamoxiclav and check local protocols)
4) Steroids – IV dexamethasone 6.6mg stat dose. CAUTION: administering IV steroids is controversial therefore check with your registrar/consultant before prescribing.
5) Analgesia and regular medications
6) Check the starving status of the patient, if they are going to theatre they need to be NBM (6 hours for food, 1 hour for clear fluids)
7) Consent the patient and mark the surgical site

References

[1] Image from: Owens R. Tooth Abscess | Causes, Symptoms and Treatments - D4Dentist Dublin [Internet]. d4dentist. 2020. Available from: http://d4dentist.ie/tooth-abscess/
[2] Thompson S, Yeung A. Anatomy Relevant to Head, Neck, and Orofacial Infections. Head, Neck, and Orofacial Infections. 2016;:60-93.
[3] Osborn H, Deschler D. Deep Neck Space Infections. Infections of the Ears, Nose, Throat, and Sinuses. 2018;:329-347.
[4] Rocha F, Batista J, Silva C, Bernardino R, Raposo L. Considerations for the Spread of Odontogenic Infections — Diagnosis and Treatment. A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2. 2015;.
[5] Image from: Restricted Jaw Movement (Trismus) [Internet]. Bccancer.bc.ca. 2020. Available from: http://www.bccancer.bc.ca/health-info/coping-with-cancer/managing-symptoms-side-effects/restricted-jaw-movement-(trismus)
[6] Candamourty, Ramesh et al. “Ludwig's Angina - An emergency: A case report with literature review.” Journal of natural science, biology, and medicine vol. 3,2 (2012): 206-8. doi:10.4103/0976-9668.101932
[7] Mohamad I, Narayanan M. “Double Tongue” Appearance in Ludwig’s Angina. New England Journal of Medicine. 2019;381(2):163-163.
[8] Image from: Moran CORE | Preseptal vs Orbital Cellulitis [Internet]. Morancore.utah.edu. Available from: http://morancore.utah.edu/basic-ophthalmology-review/preseptal-vs-orbital-cellulitis/
[9] Sebaceous cyst presenting to ED. Nottingham University Hospital. Image owner: Asad Ahmed
[10] Gan C. Dental abscess | Radiology Case | Radiopaedia.org [Internet]. Radiopaedia.org. 2020. Available from: https://radiopaedia.org/cases/dental-abscess-2
[11] Sąsiadek M. Odontogenic Inflammatory Processes of Head and Neck in Computed Tomography Examinations. Polish Journal of Radiology. 2014;79:431-438.

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