5.1 Introduction

Deep neck infections (DNIs) are commonly encountered in both children and adults. However, the presentation, progression, and management differ greatly in these two groups. The morbidity and mortality rates of DNIs have improved dramatically since the initiation of antibiotic therapy and the understanding of deep neck anatomy. Infectious and inflammatory conditions of the upper aerodigestive tract are the primary cause of DNIs. Dental infections are the most common cause of DNIs in adults, whereas oropharyngeal infections are the most common cause in children. ^{1 – 4} Diagnosis and treatment are dependent on the age of the child, the location of the infection, and the etiological agent involved. In the pediatric population, acute rhinosinusitis is a common cause of retropharyngeal lymphadenitis. Oral surgical procedures and endoscopic instrumentation may iatrogenically traumatize the pharyngo-esophageal lumen and incite an upper airway infection. Sialadenitis, with or without ductal obstruction, can precipitate infectious spread. Foreign bodies trapped within the upper aerodigestive tract may initiate infections that spread to the deep neck. Superficial infections, such as skin cellulitis, may spread along fascial planes into deeper neck compartments. Penetrating trauma may introduce pathogens into the fascial planes. Congenital or acquired lesions such as branchial cleft cysts, thyroglossal duct cysts, or laryngoceles may become infected and result in spread of infection. Congenital cysts account for 10 to 15% of DNIs in the pediatric population, and these should be suspected, especially in the setting of recurrent DNIs.

5.2 Anatomy

An understanding of deep infections of the neck requires knowledge of the anatomy of the superficial and deep cervical neck fascia and spaces. It is their relationship to each other that forms the potential neck spaces that can harbor or limit infection and abscess formation. ^{5 – 7} DNIs may be broadly classified as involving the suprahyoid spaces, infrahyoid space, or spaces involving the entire neck:

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  Suprahyoid spaces: Submandibular space, pharyngo-maxillary (lateral pharyngeal) space, masticator space, parotid space, and peritonsillar space.

  
  
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  Infrahyoid space: Visceral space.

  
  
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  Spaces involving the entire neck: Retropharyngeal space, prevertebral space, vascular (carotid) space, and “danger” space.

Infections in these spaces exert fatal effect either by local airway occlusion or extension to vital areas such as the mediastinum or carotid sheath. Fascial planes divide the neck into true and potential spaces. The deep cervical fascia of the neck can be divided into a superficial, middle (pretracheal), and deep layer (prevertebral), which envelop various structures in the neck and dictate potential routes for spread of infections. Of primary importance for deep neck space infections are the submandibular, peritonsillar, parapharyngeal, and retropharyngeal spaces (▶ Fig. 5.1).

5.3 Clinical Presentation and Preoperative Evaluation

Children with deep space neck infections more commonly present with fever, neck mass, odynophagia, dysphagia, sore throat, and decreased oral intake. These symptoms are usually present for approximately 2 to 5 days. Less common symptoms include agitation, cough, dehydration, drooling, snoring, stridor, dyspnea, and torticollis. ^{8 , 9} Important points in the history include the duration and progression of the symptoms, a recent upper respiratory tract infection, procedures performed to the neck (i.e., dental surgery, intubation), prior antibiotic therapy, recent travel, and a possible immunocompromised state. The average age at presentation is 4 to 5 years, with peritonsillar abscesses typically presenting in older children and retropharyngeal abscesses seen in younger children. ^{9 – 13}

Physical examination should assess for the presence of erythema, tenderness, and fluctuance of the neck mass, as well as lymphadenopathy, tracheal deviation, and neck stiffness. The examination of the oral cavity and pharynx should be performed with attention to the tonsillar size and symmetry, dentition, palatal edema, and uvular deviation. Though potentially life-threatening, airway compromise secondary to a DNI is very rare. An important sign of airway compromise is “tripoding,” which refers to a child in the seated position with their elbows or hands on their knees, leaning forward with the neck extended and head tilted slightly backward.

Though not mandatory, laboratory tests may be helpful in the work-up of a child with a potential DNI. Leukocytosis, with or without a left shift, is typically seen on a complete blood count. Other helpful laboratory tests include a C-reactive protein (which can aid in determining progression of infection over time), a monospot test, and Epstein-Barr virus (EBV) titers. In cases of more chronic infection, a PPD (TB and atypical TB) skin test should be considered. It is also important to consider other causes of inflammation such as congenital, neoplastic, or inflammatory conditions. ¹⁴

Contrast-enhanced CT scans is the gold standard in the evaluation of DNIs (▶ Fig. 5.2 and ▶ Fig. 5.3). CT scan provides important valuable information of the site and extent of infection. It has a sensitivity of 100% in determining the precise location of an infectious process (abscess) and a sensitivity of 88 to 95% in the ability to differentiate between cellulitis and an abscess. ¹⁵ It is also valuable in locating the relative position of the major vessels. CT scan of the chest may be helpful if extension of abscess into the mediastinum is suspected. The role for magnetic resonance imaging (MRI) is under debate. MRI was shown to be superior to CT in demonstrating disease extension, the spaces involved, and source of infection, as it is less degraded by artifacts. Ultrasound scans may also aid in the diagnosis of an abscess. However, the quality of the scan is highly operator-dependent, and there is poorer visualization of structures in the upper oropharynx. ^{11 , 12} Imaging techniques are performed according to the location of the DNI, the child’s medical condition, and whether or not clinical improvement has been seen following initiation of antibiotic treatment.

5.4 Pathogens

The types of bacteria found in neck infections vary regionally and continue to evolve over time. The microbiology of DNI often yields a mixture of aerobic and anaerobic organisms that are representative of oropharyngeal flora. Group A betahemolytic streptococcus (GABHS), Staphylococcus aureus, and anaerobes are the most commonly isolated bacteria in neck abscess cultures. ^{5 , 7 , 10 , 14 , 18} The location of the abscess has been correlated with specific bacteria. Peritonsillar, retropharyngeal, and parapharyngeal abscesses tend to be caused by GABHS, while submandibular and superficial neck abscesses are more commonly associated with S. aureus.

Other less common causes of neck infections and lymphadenopathy include atypical mycobacterium, actinomycosis, fusobacterium necrophorum (Lemierre’s syndrome), histoplasmosis, toxoplasmosis, and aspergillosis. ¹⁰

Empiric therapy for DNIs varies greatly, but should include adequate coverage of Gram-positive, Gram-negative, and anaerobic organisms. Typical choices for empiric therapy include ampicillin-sulbactam, clindamycin with a third-generation cephalosporin, trimethoprim-sulfamethoxazole, vancomycin with a third-generation cephalosporin, and linezolid. Clindamycin with a third-generation cephalosporin is a commonly used antibiotic choice, as it provides good Gram-positive and anaerobic coverage, and usually covers MRSA. ^{9 , 13 , 15 , 18 , 19}

5.5 Treatment

Treatment for deep neck abscesses depends on whether lymphadenitis or a suppurative abscess is suspected. In general, lymphadenitis and cellulitis are treated with antibiotics, whereas a neck abscess in a clinically unstable child is treated with immediate surgical drainage. ^{7 , 8 , 11 , 13} Controversy exists over the best management of a clinically stable child with a neck abscess. Clinical stability typically implies the child is without signs of systemic toxicity, airway compromise, or evidence of spread to adjacent tissue spaces. ^{11 , 13 , 20} Many studies have shown good treatment outcomes with medical management of a CT-defined neck abscess. McClay et al found that 10 of 11 children (91%) with a CT-defined neck abscess improved with intravenous antibiotics alone. ¹⁷ Complications of a neck abscess are uncommon but can carry severe morbidity and mortality. They are typically associated with a delay in diagnosis or treatment. Airway obstruction and death can occur. Rupture of a retropharyngeal or parapharyngeal abscess may result in severe pneumonitis. Septic venous thrombosis can occur, leading to septic emboli, septic shock, or neurovascular compromise. Carotid artery rupture may also result from an unresolved abscess. Spread of an infection along the danger space can rapidly lead to mediastinitis.

Most DNIs are located medial to the great vessels, while lymphadenitis is more commonly seen lateral to them. Children with clinical evidence of an abscess lateral to the great vessels typically undergo a transcervical incision and drainage under general anesthesia. The primary benefits of incision and drainage include obtaining cultures for culture-directed antibiotic therapy, removing free pus from the neck, and creating an external tract to prevent the re-accumulation of pus. External incision and drainage has been reported to be 99% successful. ¹² The risks of the surgery depend on the location of the abscess, but primarily include injury to the marginal mandibular nerve, accessory nerve, vagus nerve, or great vessels. ¹⁰