2018-19 Section 7-Neoplastic and Inflammatory Diseases of the Head and Neck eBook

Eur Arch Otorhinolaryngol (2012) 269:1241–1249

complications, such as descending necrotizing mediastini- tis and internal jugular vein trombosis, and in monitoring the evolution of the infection [ 14 ]. Although CECT scan has a good sensitivity in detecting infection and delineating the cervical spaces involved, its accuracy is lower in dif- ferentiating abscess from cellulitis [ 15 , 16 ]. A single or multiloculated low density area with a complete circum- ferential rim of enhancement, surrounded by soft tissue swelling, is considered the hallmark of abscess. Also, the presence of an air-fluid level and subcutaneous air are findings suggesting an abscess formation [ 17 ]. Deep neck cellulitis presents as a mass with low-density core and surrounding edema without enhancing rim or air-fluid level [ 16 ]. On the other hand, lymphadenitis presents as a soft tissue swelling obliterating adjacent fat planes. It is lapal- issian that, as the diagnosis of deep neck abscess is based on subjective findings, the accuracy of CECT is dependent upon the experience of the radiologist and may be con- siderably lower in the transition stages from cellulitis to abscess. In the present series, intraoperative findings did not confirm the CT diagnosis of abscess in 13%. It has been reported that pus may not be intraoperatively found in up to one-fourth of cases with CECT scans suggestive of deep neck abscess [ 18 ]. A scalloped contour of the ring- enhancement, was more recently found to have a positive predictive value of 94% in predicting the presence of pus [ 19 ]. In order to identify periapical infections in patients with suspected odontogenic DNIs, acquisition of high- resolution axial scans of the jaw together with curved and orthoradial multiplanar reconstructions are desirable [ 20 ]. On CECT, internal jugular vein thrombosis appears as an enlarged vein with a low-density lumen surrounded by a sharply defined wall [ 21 ] (Figs. 1 , 2 ). In patients with descending mediastinitis (Figs. 3 , 4 ), CECT may show fluid collection with gas formations, soft tissue thickening and enhancement with loss of the normal fat planes, pleural or pericardial effusion [ 22 ]. As descending mediastinitis may be clinically silent [ 22 ], we suggest to routinely extend the CT scans to the superior mediastinum in all cases of DNI. The mainstay of treatment of DNIs consists of airway control, effective antibiotic therapy, and, when appropriate, surgical incision and drainage of the pus collection. The maintenance of a secure airway, a challenging task both for surgeon and anesthesiologist, is the first step in the treatment of patients with DNIs and airway compro- mise. Upper airway obstruction may result from laryngeal edema secondary to anterior visceral space involvement or tongue pushing against the roof of the mouth and the posterior pharyngeal wall secondary to extensive sub- mandibular space infection. In the present series about half of patients with critical airway were affected by Ludwig’s angina, a potentially life-threatening bilateral

than two thirds of DNIs contain beta-lactamase-producing microorganisms. The low tissue oxygen tension in the loose areolar tissue of the cervical spaces favor the syn- ergistic growth of aerobic and anaerobic bacteria. Strep- tococcus spp and Bacteroides spp were the most prevalent microorganism in aerobic and anaerobic bacterial cultures, respectively, reflecting the predominant pharyngeal source of DNIs in the present series. No bacterial growth was recorded in 188 patients and anaerobes were isolated in minority of cases. Use of antibiotics before admission, high-dosage intravenous empiric antibiotic therapy prior to surgical drainage, improper collection of specimen, no routine use of anaerobic cultures, and difficult in culturing anaerobes may affect and may have affected the result of microbiological tests in this series. Increase in the inci- dence of anaerobic bacteremias with multiple-drug-resis- tant organisms is emerging as a significant health problem as there is an increasing population with multiple comor- bidities and compromised immune system [ 10 ]. Anaerobes express significant virulence factors including adherence and spreading factors as hyaluronidase, collagenase, and fibrolysin that may promote the dissemination of a local- ized infection [ 7 ]. Anaerobes also have the ability to pro- duce the enzyme beta-lactamase protecting themselves and other penicillin-susceptible organisms from the activity of penicillins [ 11 ]. Therefore, all efforts should be directed to maximize successful isolation of anaerobes. In order to increase the chances of effective microbiological diagnosis, the speci- men for anaerobic cultures should be an aspirate obtained by needle and syringe, transferred into anaerobic culturette, avoiding exposure to oxygen, and transported to the labo- ratory within 2–3 h [ 7 ]. Tissue samples and biopsies placed in a sterile container are also adequate specimens for anaerobic cultures. The high rate of coagulase-negative Staphylococcus positive culture may reflect the collection of contaminated specimens. In this sense, when the mate- rial for microbiological cultures is transmucosally col- lected, it is essential to decontaminate the mucous membrane. Although no methicillin-resistant strains were identified, as community-associated methicillin-resistant Staphylococcus aureus (MRSA) isolation is increasingly common among out- and inpatients with suppurative infections, MRSA may play an increasing role in DNIs in the next future [ 12 , 13 ]. CECT was the modality of choice in the evaluation of DNIs. Taken into account that trismus may significantly limit an accurate inspection of the upper aerodigestive tract and that clinical examination may underestimate the extent of infection in about two-third of cases, CECT plays a critical role in confirming the clinical suspect of DNIs, in the differentiation of deep neck abscesses from cellulitis, in the delineation of the involved spaces, in the diagnosis of

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