Neck Abscess

Etiology

Historically, before antibiotics, tonsillitis and pharyngitis were the most frequent causes of deep neck space infections. Tonsillitis remains the most common cause of deep neck space infection in children, but in adults, an odontogenic origin is the most common. Other causes include oral surgical procedures, salivary gland infection or obstruction, trauma to the oral cavity or pharynx, instrumentation, foreign body aspiration, intravenous drug use, cervical lymphadenitis/suppuration of malignant lymph node or mass, branchial cleft anomalies, thyroglossal duct cyst, and others. There may be no clear source for 20% to 50% of deep neck infections. It is important to consider a suppressed immune system due to HIV/AIDS, chemotherapy, or immunosuppressant medications in these infections.[4]

Epidemiology

Deep neck infections are common. As they comprise many discrete entities, it is difficult to accurately estimate the number of deep neck space infections in the United States or worldwide. It would be reasonable to assume that the incidence in the United States is lower than in countries where immunizations and/or early medical intervention for more superficial infections are unavailable. A 2009 study by Adeil et al estimated more than 3,400 U.S. pediatric hospital admissions per year for deep neck space infections.

Peritonsillar abscess is most common in 20- to 40-year-olds. Children are not often affected by a peritonsillar abscess but can be if they are immuno-compromised. Females and males are affected equally. Chronic tonsillitis or multiple rounds of oral antibiotics may predispose a person to the formation of a peritonsillar abscess.

Parapharyngeal abscesses can develop in any age patient but are most common in children and adolescents. Immunocompromised adults are also at increased risk.[5]

Pathophysiology

There are different potential paths of infection in the neck. Oral cavity/face/superficial neck infection can spread via the lymphatic system to the deep tissues of the neck. Lymphadenopathy may cause suppuration and then focal abscess formation. Direct communication between tissues in the neck may occur. Finally, penetrating trauma can introduce infection to the deep tissues. 

After the spread of infection, local inflammation or phlegmon may develop, or a fulminant abscess may form with a purulent fluid collection. Signs of neck abscess in the deep tissues may result from either the mass effect of inflamed tissue or abscess on the surrounding structures or from direct involvement of those structures with the infection. Examples of different types of spread include the following:

1. A lateral pharyngeal space infection can spread to the carotid sheath, causing internal jugular vein thrombosis, leading to subacute bacterial endocarditis or other thromboembolic diseases.
2. Lateral pharyngeal space infection can lead to extensive edema, causing respiratory compromise.
3. Tonsillitis may lead to a peritonsillar abscess, which in turn leads to a lateral/posterior pharyngeal infection that can spread to the chest if untreated.

This can lead to mediastinitis or empyema. Neck abscesses can include peritonsillar infections, retropharyngeal infections, submandibular infections, buccal infections, parapharyngeal space infections, and canine space infections. The retropharyngeal, retroesophageal, and posterior mediastinum are all continuous spaces for the spread of infection. 

Organisms involved in deep neck infections include aerobes and anaerobes, frequently with a predominance of oral flora. Organisms frequently cultured include Streptococcus, Bacteroides, Staphylococcus, Peptostreptococcis, Pseudomonas, E coli, and H influenzae.

Histopathology

Causative organisms for deep neck infections include gram-positive organisms, including but not limited to Streptococcus viridans, Staphylococcus epidermidis, and Staphylococcus aureus; and gram-negative organisms, including but not exclusively Escherichia coli, Klebsiella oxytoca, and Haemophilus influenza. In studies of retropharyngeal abscesses, polymicrobial results were found in almost 90% of patients. Aerobes were found in all patients, and anaerobes in more than half. Anaerobes may include Peptostreptococcus, Fusobacterium, Prevotella, and Actinomyces. Other bacteria may include Lactobacillus, Bacteroides, and Propionibacterium, among others. Some studies show cultures with an average of at least 5 isolates. There have been studies showing an association between the presence of biofilm and abscess development.[6]

Toxicokinetics

Within the neck are 11 zones created by planes of lesser and greater resistance between the fascial layers. These potential spaces can expand, communicate with each other, and permit the infection to spread. The spaces include the parapharyngeal or lateral pharyngeal space, which is superior to the hyoid bone. The skull base is the superior margin, and the medial boundary is the middle layer of the deep cervical fascia.

History and Physical

Deep neck space abscess should be considered when patients describe any or many of the following:

• Severe pain
• Recent dental procedures
• Upper respiratory infection
• Neck or mouth trauma
• Respiratory distress
• Dysphagia or dysphonia
• Immunosuppression
• The rapid rate of onset
• Prolonged duration of symptoms

Particular red flags include neck asymmetry, neck masses, lymphadenopathy, trismus, medial displacement of the lateral pharyngeal wall and tonsil, torticollis, cranial nerve involvement, spiking fevers, and tachypnea/shortness of breath.

Evaluation

CT imaging of the neck can help confirm and localize the presence of a deep neck infection. However, patients are often too unstable for CT imaging or unable to lie flat on the CT table to perform the CT. There may be situations where only a portable lateral soft tissue neck x-ray can be obtained, which can help support the diagnosis of neck abscess without much help in localization. In cases where an early neck abscess is suspected, an otolaryngologist may be called upon to perform direct laryngoscopy to ascertain the presence of swelling.[7] If a dental source is suspected, then a panoramic view is necessary. Blood work should be obtained, including electrolytes, clotting profiles, blood cultures, and abscess cultures.

Treatment / Management

Treatment involves adequate drainage of the abscess in the operating room. Also, antibiotic therapy is paramount. Because cultures are unavailable during presentation, empiric antibiotics are started at presentation. A study in 2008 by Yang et al found 3 comparable antibiotic regimens: (1) ceftriaxone and clindamycin, (2) ceftriaxone and metronidazole, or (3) penicillin G and gentamicin and clindamycin.

In a 2015 Iranian study by Motahari et al, 428 of 815 cases were managed surgically, while the rest were managed medically. Tracheostomy was performed in 5 cases. One 15-year-old with symptoms suggestive of mediastinitis died of airway compromise a day after undergoing surgical management of a parapharyngeal abscess. The study concluded that prompt surgical management is indicated if medical management fails after 24 to 48 hours or if fluctuance or any complications are present.

It is important to determine the problem's underlying cause and address that specifically. For example, with odontogenic infections, early dental extraction is crucial. Airway management must always be a consideration, as there is often swelling and distortion of anatomy; the surgical airway may be preferable. Certainly, in cases of deep neck infection, early notification of otolaryngology and anesthesia for airway backup is wise. Prompt transfer to the operating room for simultaneous evaluation, airway management, and treatment may be life-saving for patients presenting with a compromised airway.[8][9]

Differential Diagnosis

The differential diagnoses for neck abscesses include the following:

• Epiglottis

• Esophagitis

• Gastrointestinal foreign bodies

• Infectious mononucleosis

• Kawasaki disease

• Mediastinitis

• Meningitis

• Pharyngitis

• Sinusitis imaging

• Trachea foreign bodies