SA–CME Information

SA-CME

SA–CME Information

Imaging Acute Face and Neck Infections

Description Authors Many acute infectious conditions of the face and neck re- Blair A. Winegar, MD, is an Assistant Professor in the De- sulting from common sources, such as pharyngitis, dental partments of Medical Imaging, Ophthalmology and Vision infection, and penetrating trauma, are evaluated in the emer- Science, and Neurosurgery; Ethan A. Neufeld, MD, is an As- gency department. The clinical features of these conditions sistant Professor in the Department of Medical Imaging; and overlap, and clinical evaluation is often insufficient to localize Dr. Kubal is a Professor in the Departments of Medical Imag- or determine the extent of infection within the deep spaces of ing and Neurosurgery, all at the University of Arizona College the neck. of Medicine, Tucson, AZ. This article showcases the classic imaging features and locations of a variety of acute face and neck infections encoun- Target Audience tered in the emergency department. In addition, the imaging • Radiologists findings of potentially life-threatening complications, such as • Related Imaging Professionals mediastinitis resulting from retropharyngeal abscess and septic pulmonary emboli resulting from Lemierre syndrome, are System Requirements described. In order to complete this program, you must have a com- In the emergency setting, the radiologist’s ability to cor- puter with a recently updated browser and a printer. For as- rectly identify and categorize acute face and neck infections sistance accessing this course online or printing a certificate, and their complications is paramount to direct appropriate sur- email [email protected]. gical and medical management. Instructions Learning Objectives This activity is designed to be completed within the des- After completing this activity, the participant will be able to: ignated time period. To successfully earn credit, participants • Describe pathophysiology, clinical features, and treat- must complete the activity during the valid credit period. To ments for a variety of acute face and neck infections con- receive SA–CME credit, you must: fronted in the emergency department; • Discuss the classic imaging findings and locations of fre- 1. Review this article in its entirety. quently encountered acute face and neck infections; and 2. Visit www.appliedradiology.org/SAM2. • Recognize potential complicating features of acute face 3. Login to your account or (new users) create and neck infections which may be detected on imaging. an account. 4. Complete the posttest and review the discussion Accreditation/Designation Statement and references. The Institute for Advanced Medical Education is accredited 5. Complete the evaluation. by the Accreditation Council for Continuing Medical Educa- 6. Print your certificate. tion (ACCME) to provide continuing medical education for physicians. Estimated time for completion: 1 hour The Institute for Advanced Medical Education designates this Date of release and review: May 1, 2020 journal-based CME activity for a maximum of 1 AMA PRA Cat- Expiration date: April 30, 2022 egory 1 Credit™. Physicians should only claim credit commen- surate with the extent of their participation in the activity. Disclosures These credits qualify as SA-CME credits. No authors, faculty, or any individuals at IAME or Applied Radiology who had control over the content of this program have any relationships with commercial supporters.

Imaging Acute Face and Neck Infections

Blair A Winegar, MD; Ethan A Neufeld, MD; Wayne S Kubal, MD

variety of acute infectious dis- A B orders of the face and neck, resulting from such common Asources as pharyngitis, dental infection, and penetrating trauma, may present to the emergency department. Clinical lo- calization of such infections, especially those involving the deep neck, is lim- ited. In one series of patients with deep neck involvement, clinical examination localized the space involved in only 42.9% of cases.1 Accurate characterization of infections can determine the FIGURE 1. Dental abscess. (A) Coronal contrast-enhanced CT (CECT) on bone algorithm most appropriate therapy; ie, aspiration/ demonstrates right maxillary molar dental caries and periapical lucency (arrowhead) compati- drainage versus antibiotic therapy. ble with dental abscess. (B) Axial CECT shows a rim-enhancing fluid collection along the right buccal surface of the maxillary alveolar ridge, compatible with an associated subperiosteal Nevertheless, despite widespread ac- abscess of dental origin (arrow). cess to antibiotics, face and neck infections still present significant morbidity periapical abscesses. Infection can also fascia, which encompasses the muscles and mortality. Potentially life-threat- arise from the tissues along the mar- of mastication and a portion of the pos- ening complications, including airway gins of the tooth roots, and is known as terior mandible. Dental infections of obstruction, mediastinitis, and septic a periodontal abscess. Such abscesses the posterior mandibular molars may emboli, are reported in 10-20% of deep can result in focal cortical destruction breach into the masticator space, result- neck infections.2,3 Emergency radiolo- of the alveolar ridge and extend into the ing in abscess formation that may clini- gists play a critical role in diagnosing, adjacent subperiosteal and extraosseous cally present as trismus. localizing, characterizing, and identi- spaces, resulting in facial cellulitis. On CT, a rim-enhancing fluid col- fying the complications resulting from On computed tomography (CT), os- lection along the posterior margin acute face and neck infections. seous lucency around the tooth root of the mandible close to the muscles apex suggests a periapical abscess (Fig- of mastication is compatible with a Dental Abscess ure 1A).4 Rim-enhancing fluid collec- masticator space abscess (Figure 2A). Dental caries, broken teeth, or peri- tions and associated inflammatory fat Imaging should cover the superior ex- odontal disease can predispose teeth stranding in the adjacent buccal space tent of the temporalis muscles, as the and adjacent soft tissues to bacterial are compatible with extension of infec- masticator space continues superiorly infections. Dental abscesses, focal col- tion (Figure 1B). An osseous breach of above the zygomatic arch to the pari- lections of pus associated with bacterial the alveolar ridge between the periapical etotemporal scalp (Figure 2B).5 The infection, occur most commonly adja- abscess and adjacent subperiosteal or ex- ipsilateral mandibular teeth should cent to the tooth root tip, and are termed traosseous abscess is frequently present. be assessed for underlying dental abscess. Additional potential infectious Affiliations: University of Arizona Masticator Space Abscess sources include septic arthritis of the College of Medicine, Tuscon AZ. The The masticator space is contained by temporomandibular joint and coales- authors declare no conflicts of interest. the superficial layer of the deep cervical cent mastoiditis.

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FIGURE 2. Masticator space abscess. (A) Axial CECT demonstrates a loculated rim-enhancing fluid collection along the left mandibular ramus and muscles of mastication, compatible with masticator space abscess (arrow). (B) Axial CECT shows extension of this abscess into the supra- zygomatic masticator space along the left temporalis muscle (arrowhead).

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FIGURE 3. Ludwig angina. (A) Axial CECT shows extensive inflammatory stranding and phlegmon within the sublingual spaces (arrowheads). (B) Coronal CECT demonstrates inflammatory stranding in the submandibular spaces (arrows) in addition to the sublingual spaces (arrowheads) in this case of Ludwig angina.

Ludwig Angina ing and swelling within the bilateral lucency with potential lingual cortical Ludwig angina is a potentially life- sublingual spaces in the floor of mouth breakthrough involving a second or third threatening bacterial cellulitis of the sub- (Figure 3A).7 Additional inflammatory mandibular molar suggests the inciting lingual and submandibular spaces that stranding in the fat of the submandibular dental abscess. can result in acute airway compromise. spaces inferior and lateral to the mylohy- This infection is most commonly the oid muscles is typically present (Figure Odontogenic Sinusitis result of extension of infection from an 3B). Rim-enhancing fluid collections Dental abscesses adjacent to the roots odontogenic source.6 On CT, Ludwig an- compatible with abscesses occasionally of the maxillary premolars and molars gina demonstrates inflammatory strand- may be seen. Presence of a periapical may result in inflammatory mucosal

FIGURE 4. Odontogenic sinusitis. Coronal CT shows a left maxillary FIGURE 5. Tonsillitis. Axial CECT demonstrates bilateral enlarged molar periapical lucency with dehiscence into the left maxillary sinus palatine tonsils (arrow) with linear enhancing striations (“tiger (arrow). The adjacent left maxillary sinus is filled completely indicating stripe” appearance) which touch in the midline (“kissing tonsils”) in odontogenic sinusitis. this case of tonsillitis secondary to infectious mononucleosis. unit pattern of obstructive paranasal ria gonorrhoeae, and Corynebacterium sinus disease with ipsilateral anterior diphtheriae are rare bacterial causes of ethmoid and frontal sinusitis. Treatment tonsillitis. Treatment for tonsillitis is for odontogenic sinusitis centers around typically supportive with anti-inflam- clearing the dental abscess with antibi- matories/analgesics for viral etiologies, otics and root canal or dental extraction. with the addition of antibiotics for con- On CT, odontogenic sinusitis typi- firmed bacterial causes. cally demonstrates unilateral maxillary On contrast-enhanced CT, tonsilli- sinus inflammatory mucosal thickening tis is evidenced by enlarged palatine and sinus fluid with concomitant adja- tonsils, which can touch in the midline cent oroantral fistula, periodontal disease of the oropharynx, termed “kissing with projecting tooth root, or periapical tonsils” (Figure 5).11 The tonsils also abscess (Figure 4).9 Osseous dehiscence typically demonstrate a striated, “tiger between the periapical lucency and max- stripe” appearance in which the enhanc- illary sinus may be present. ing mucosal lining along the crypts is FIGURE 6. Peritonsillar abscess. Axial contrasted by low-density edema within CECT shows a rim-enhancing fluid collec- Tonsillitis the submucosa of the glands. tion with adjacent inflammatory stranding along the lateral margin of the left palatine Tonsillitis is a type of pharyngitis re- tonsil resulting in mild narrowing of the oro- sulting from inflammation of the palatine Peritonsillar Abscess pharyngeal airway, consistent with periton- tonsils, typically from a rapidly progres- The most common ENT emergency sillar abscess (arrow). sive infection. Most cases are the result is peritonsillar abscess, a complication thickening or acute bacterial sinusitis of viral infection, most commonly due to of untreated or incompletely treated of the adjacent maxillary sinuses, adenovirus, rhinovirus, influenza, coro- bacterial tonsillitis. Peritonsillar ab- termed odontogenic sinusitis. This navirus, or respiratory syncytial virus.10 scess occurs as infection spreads deep often-overlooked etiology of parana- Epstein-Barr virus can also cause ton- between the tonsillar capsule and su- sal sinus disease results in up to 40% sillitis as part of infectious mononucle- perior constrictor muscle, forming a of unilateral maxillary sinusitis.8 Al- osis. Approximately 20% of tonsillitis collection of pus.12 Since peritonsillar though isolated maxillary sinusitis is results from bacterial infection, typically abscesses necessitate more aggressive the most common form, inflammatory following a preceding viral infection. management, such as aspiration of pus mucosal thickening can extend through The most common bacterial etiology is and adding steroids to antibiotics, im- the maxillary infundibulum to the mid- Group A Streptococcus, known as strep aging characterization directly affects dle meatus, resulting in an ostiomeatal throat. Haemophilus influenzae, Neisse- patient management.

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FIGURE 7. Lemierre syndrome. (A) Axial C CECT shows filling defect within the left inter- FIGURE 8. Retropharyngeal suppurative nal jugular vein with peripheral enhancement lymphadenitis. Axial CECT demonstrates and surrounding inflammatory stranding a focal rim-enhancing fluid collection within (arrow), consistent with septic thrombophle- the right lateral aspect of the retropharyn- bitis. (B) Axial CECT demonstrates a rim-en- geal space (arrow) in this case of retropha- hancing fluid collection along the left palatine ryngeal suppurative lymphadenitis. tonsil (black arrowhead), compatible with the inciting peritonsillar abscess. (C) Axial CECT tentially life-threatening complication demonstrates bilateral airspace disease with of peritonsillar abscess.14 This infection right lower lobe cavitary nodule (white arrow- most commonly occurs following the head), compatible with septic pulmonary spread of the anaerobic bacteria Fuso- embolus in this case of Lemierre syndrome. bacterium necrophorum, a constituent of the normal oral flora, to the IJV. In- fectious thrombi can break off from the A B IJV and travel to the lungs, resulting in pulmonary septic emboli. Less commonly, septic microemboli can bypass the pulmonary capillaries and cause infection or infarctions elsewhere in the body, typically septic arthritis of the large joints. Intravenous antibiotics targeting anaerobic organisms and peritonsillar abscess drainage (if present) is first-line treatment for Lemierre syndrome. Ligation of the IJV occasionally may be necessary. On CT, IJV thrombophlebitis shows FIGURE 9. Retropharyngeal abscess. (A) Axial CECT demonstrates fluid and gas filling the non-opacification of the vein lumen retropharyngeal space with thickened and enhancing wall (arrow), compatible with retro- with a thickened, enhancing wall and pharyngeal abscess. (B) Sagittal CECT confirms extension of the retropharyngeal abscess adjacent inflammatory stranding (Fig- (arrow) inferiorly into the mediastinum (arrowhead). ure 7A).15 There is typically an ipsilat- On CT, peritonsillar abscesses will stranding in the adjacent neck soft tis- eral peritonsillar abscess (Figure 7B). appear as rim-enhancing fluid collec- sues, usually in the fat of the parapha- Pulmonary septic emboli in the partially tions along the deep margins of the ryngeal and retropharyngeal spaces. visualized portions of the lung apices inflamed palatine tonsil (Figure 6).13 are also sometimes detected on CT of These collections can result in local- Lemierre Syndrome the neck. Pulmonary septic emboli ap- ized mass effect with narrowing of the Infectious thrombophlebitis of the pear as nodular opacities with ill-de- oropharyngeal airway. These abscesses internal jugular vein (IJV), also known fined margins, typically within internal also typically result in inflammatory as Lemierre syndrome, is a rare and po- cavitation (Figure 7C).

A B A

FIGURE 10. Calcific tendinitis of the longus colli. (A) Lateral radiograph of the neck soft tissues demonstrates amorphous calcification along the inferior margin of the anterior arch of C1 (arrow) with associated thickening of the prevertebral soft tissues (arrowhead). (B) Sagittal B CECT confirms amorphous calcification in the insertional fibers of the longus colli (arrow) and associated retropharyngeal edema (arrowhead) in this case of calcific tendinitis of the longus colli. Note absence of peripheral rim enhancement along the retropharyngeal space.

Retropharyngeal Suppurative condition most frequently is the result Lymphadenitis of a penetrating trauma with inoculation Retropharyngeal suppurative of normal oral flora into the retropha- lymphadenitis denotes lateral retro- ryngeal space. Retropharyngeal spread pharyngeal lymph node inflammation of infection from adjacent cervical dis- resulting from a bacterial infection citis-osteomyelitis or ruptured retropha- that has progressed to internal lique- ryngeal suppurative lymphadenitis in faction. This condition is most com- children are other potential etiologies. monly encountered in young children Retropharyngeal abscesses may spread (2-6 years of age) exhibiting fever, to the danger space, a potential space sit- neck pain, dysphagia, and/or torti- uated between the true retropharyngeal collis. The most commonly involved space and prevertebral musculature. This bacteria are Streptococcus sp. and permits free communication to the medi- C Staphylococcus aureus.16 Intravenous astinum, resulting in the dreaded compli- antibiotics are the first-line treatment cation of mediastinitis.18 Treatment with for this infection, with aspiration or IV antibiotics and surgical drainage is surgical drainage reserved for refrac- standard of care. tory cases or large fluid collections. On CT, retropharyngeal abscesses On CT, a rim-enhancing fluid col- are rim-enhancing fluid collections that lection confined to the lateral margin of fill the retropharyngeal space (Figure the retropharyngeal space with adjacent 9A).19 Larger fluid collections typically inflammatory stranding is compatible demonstrate bowing of the walls of the with retropharyngeal suppurative lymph- retropharyngeal space. In cases of ret- adenitis (Figure 8).17 There is typically ropharyngeal abscess, it is essential to associated retropharyngeal edema or ef- image the chest to search for inflamma- fusion, but rim-enhancing fluid should tory stranding or rim-enhancing fluid FIGURE 11. Epiglottitis/supraglottitis. (A) Lat- not cross the midline or fill the retropha- collections in the mediastinum, indicat- eral radiograph of the neck soft tissues shows ryngeal space, which would suggest de- ing the complication of mediastinitis the “thumb sign” with thickening of the epi- velopment of a retropharyngeal abscess. (Figures 9B & C). glottis (arrowhead). (B) In a different patient, sagittal CECT shows thickening of the epiglottis (arrowhead) and submucosal edema Retropharyngeal Abscess Calcific Tendinitis of the involving the supraglottis (arrow). (C) Axial Infection from pus-forming bacteria Longus Colli CECT demonstrates thickening and submu- in the retropharyngeal space results in Calcific tendinitis is a self-limit- cosal edema involving the supraglottic larynx retropharyngeal abscess. In adults, this ing inflammatory response to calcium (arrows) in this case of supraglottitis.

hydroxyapatite crystal deposition into In children, diagnostic evaluation with 7. Nguyen VD, Potter JL, Hersh-Schick MR. Ludwig the tendons of the longus colli mus- upright frontal and lateral radiographs angina: an uncommon and potentially lethal neck infection. AJNR Am J Neuroradiol. 1992;13(1): cles, typically at their superior inser- of the neck is standard of care, as supine 215-219. tions at the C1-C2 level. Although not positioning for radiographs or CT may 8. Vestin Fredriksson M, Öhman A, Flygare L, et al. an infection, this inflammation affects precipitate respiratory compromise. When maxillary sinusitis does not heal: Findings on the prevertebral and retropharyngeal CBCT scans of the sinuses with a particular focus On lateral radiographs, the epiglottis on the occurrence of odontogenic causes of max- spaces, and can result in symptoms is thickened, giving the classic “thumb illary sinusitis. 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