Retropharyngeal Abscess in an Adult With Pneumonia During COVID-19 Outbreak

Background: Retropharyngeal abscesses are rarely reported in adults and occur mostly in patients with immunocompromised or as a foreign body complication. Admittedly, the treatment of retropharyngeal abscesses frequently involves surgical drainage to achieve the best results. However, when retropharyngeal abscesses occurred in a highly suspected patient with COVID-19, the managements and treatments should be caution to prevent the spread of the virus. Clinical Presentation: On February 13, a 40-year-old male with retropharyngeal abscesses turned to our department complaining dyspnea and dysphagia. In addition, his chest CT scan shows a suspected COVID-19 infection, thus making out Multiple Disciplinary Team determine to perform percutaneous drainage and catheterization through left anterior cervical approach under the guidance of B-ultrasound. Finally, the patient recovered and was discharged from the hospital on February 27 after 14 days of isolation. There was no recurrence after half a year follow-up. Conclusions: By presenting this case, we aim at raising awareness of different surgical drainage methods and summarizing our experience in the management of retropharyngeal abscesses during the outbreak of COVID-19.

R etropharyngeal abscess is a serious and occasionally life-threatening infection in the deep spaces of the neck in that the special anatomical location and the potential to obstruct the upper airway. 1 The classical signs and symptoms include fever, sore throat, hypersalivation, reduced oral intake, odynophagia, swelling on the neck, torticollis, limitation in neck mobility, and voice changes. Retropharyngeal abscess is located between prevertebral fascia and pharyngeal mucosa which is occupied by a lymph-node basin that serves as the common final drainage point of the nasal cavity, nasopharynx, oropharynx, hypopharynx, and larynx. These lymph nodes become regressed with age which explains why RPA is encountered more in early childhood. 2,3 In adults, they are rarely reported and most of the reports suggest that the occurrence is related to immunocompromised condition or local trauma, such as foreign body ingestion or instrumental procedures. 4 Therefore, retropharyngeal abscess requires promptly diagnosis and timely treatments, especially surgical drainage. However, during the outbreak of COVID-19, almost all the infectious diseases associated with fever will attract the attention of medical staff. How to deal with the other health problems of highly suspected patients with COVID-19 has become a hot topic nowadays. The case reports our experience on how to deal with the retropharyngeal abscess occurred in a highly suspected patient with COVID-19.

CLINICAL PRESENTATION
A 40-year-old male with low-grade fever (37.58C) turned to our department complaining one week of sore throat, cervicodynia, and dysphagia in Feb. The chest CT scan suggested a disputable COVID-19, as shown in Figure 1A, and he has a suspicious contact history with a COVID-19 patient during seeking medical treatment.
Although the blood routine test showed that white blood cells were 18 Â 10 9 /L, percentage of neutrophils was 79.3%, percentage of lymphocytes was 7.4%, and two-time nucleic acid tests were both negative, the possibility of COVID-19 could not be completely excluded. Therefore, the patient was admitted to the transitional ward, which was a separate room for clinical diagnosis of highly suspected patients with COVID-19. One week after treatment with the combination of Linezolid, Imipenem, Azithromycin, and Metronidazole, the symptoms did not improve at all. The condition of the patient was poor because of dysphagia and a five-year history of poorly controlled diabetes (weight reduction of about 10 kg in a month, albumin: 32.5 g/L, serum sodium: 126 mmol/L, blood chlorine: 84 mmol/L; blood gas analysis suggests metabolic acidosis, fasting blood glucose: 13.3 mmol/L, glycosylated hemoglobin: 14.1%, urine sugar þ, urine ketone body þþþ). Cervical MRI examination revealed anterior vertebral abscess at C2-T2 level ( Fig. 1B-D). Finally, the Multiple Disciplinary Team decided to perform percutaneous drainage and catheterization through left anterior cervical approach under the guidance of B-ultrasound. About 350 mL of tawny viscous pus was extracted by puncture, and then a tube was placed for continuous drainage after washing the purulent cavity with metronidazole sodium chloride solution. Immediately after operation, the dysphagia recovered well. After continuous drainage and anti-infective treatment, the chest CT and cervical MRI were re-examined ( Fig. 1E-H). Eventually, the patient recovered and was discharged from the hospital on February 27 after 14 days of isolation. There was no recurrence after half a year follow-up.

DISCUSSION AND CONCLUSION
Retropharyngeal abscess has been documented worldwide, which can present an immediate life-threatening emergency, with potential for airway compromise and other catastrophic complications. 5 The retropharyngeal space, extends from the skull base to the chest, lies posterior to the pharynx, bound by the buccopharyngeal fascia anteriorly, the prevertebral fascia posteriorly, and the carotid sheaths laterally. 6 Most of retropharyngeal abscess originates from multiple microorganisms, such as group A beta-hemolytic streptococcus, staphylococcus aureus, and upper respiratory tract anaerobic organisms. 2 The therapeutic effect of antibiotics on retropharyngeal abscess with polymicrobial origin is slow, and it is easy to cause serious complications, such as mediastinal abscess, thus making surgical treatment be the first choice of retropharyngeal abscess.
It is reported that retropharyngeal abscess is more common in children between the ages of two to four than in adults, and the mortality rate estimated between 1% and 2%. 7 Once descending mediastinitis occurs, the mortality rate approaches 25%, despite the use of antibiotic therapy. 8,9 Moreover a study in Germany of 234 adults with deep space infections of the neck shows the mortality rate was 2.6%, which mainly due to these abscesses association with airway obstruction, mediastinitis, aspiration pneumonia, epidural abscess, jugular venous thrombosis, necrotizing fasciitis, sepsis, and erosion into the carotid artery. 10 Compared to children with the abundance of retropharyngeal lymph nodes, adults abscesses is rarely caused by nasal or pharyngeal infection but usually secondary to local trauma, such as foreign body ingestion or instrumental procedures. 7,11 In our case, the principal etiology might be immunocompromised condition caused by long-term untreated diabetes mellitus and severe lung infection.
Recent studies have helped clarify the clinical diagnosis of retropharyngeal abscess is based on the specific imaging tests including lateral neck radiograph, neck CT or MRI scan and neck ultrasound rather than nonspecific and variable clinical symptoms such as sore throat, fever, neck pain, and dyspnoea. [12][13][14][15] The MRI scan performed an important role in diagnosis of our case, within which the shape, size, and boundary of the abscess are all clear at a glance. In addition, neck ultrasound contributes more to the treatments than the diagnosis because of its real-time and portability.
The conventional surgical treatment of retropharyngeal abscess is drainage via lateral cervical incision and oropharyngeal puncture. However, we chose the percutaneous drainage and catheterization under the guidance of B-ultrasound in the case for several reasons. Firstly, the local anesthesia can not only reduce the risk of anesthesia in patients with pneumonia, but also effectively prevent the spread of infection via respiratory secretions and aerosol. Secondly, The abscess is huge in size, from the oropharynx to the top of the mediastinum, with the two sides clinging to the carotid sheath. Therefore, percutaneous drainage is the most minimally invasive and the least risky, compared with drainage via lateral cervical incision and oropharyngeal puncture.
The outbreak of COVID-19 in China was the most serious public health event over the past decade. COVID-19 is an infectious respiratory disease caused by the virus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), belonging to the coronavirus family. An infected person may develop symptoms after the incubation period, which may range from two to 14 days (rarely 29 days), during which the virus can be transmitted by the person or by something close to him. [16][17][18] According to Van Doremalen et al and Kampf et al,19,20 aerosol and surface virus transmission is plausible, since it can remain viable and infectious for hours or up to nine days in a room. Several new cases of infection in China recently confirm the existence of the transmission. Therefore, hospitals, especially dentistry and otolaryngology departments, have many infection risks inward or outpatient work, because of the numerous operating instruments and oropharyngeal operations.
Actually, many clinicians have changed their way of working, shifting to remote or smart working like conducting telephone consultations to control the epidemic. However, although this could be useful for controlling patient health status, medical and dental services cannot be based exclusively on remote assistance, because they are medical disciplines founded on experience and patient contact. 21 To prevent infection, A lot of protection was invented by clinicians in dentistry and otolaryngology departments, such as ''A Technical Note for Producing Connectors to Breathing Devices'' and ''A device for collecting blood during upper respiratory and/or nasopharynx surgery.'' 22,23 Moreover, it is more FIGURE 1. A to H are the results of chest CT scan and cervical MRI scan during hospitalization, of which A to D are the results of preoperative examination and E to H are the results of postoperative examination. A shows scattered ground glass patchy shadows of bilateral lungs. B shows anterior lesions of vertebral body in sagittal plane, which spread from the oropharynx to the top of mediastinum and is suspected of the abscess of posterior pharyngeal wall. C shows the abscess base in coronal plane, which is close to the carotid sheath on both sides and the mediastinum below. D shows that the abscess is huge and close to the carotid sheath of both sides in the horizontal plane. In E, the bilateral pneumonia improves significantly compared with A. In F to H, the abscess almost disappeared and residual abscess cavity was found.
important to prevent and control the spread of the virus in patient contact and clinical operation. In the case, to reduce the possibility of pathogen transmission, the patient was treated in the transitional ward, which is a separate room for suspected COVID-19 patients, and the operation was completed in an independent laminar flow operating room.