3 Deep Neck Infections

Question 1

What are deep neck space infections?

Answer 1

Deep neck space infections (DNSI) encompass a wide spectrum of infectious disorders of the neck. DNSI are typically classified by the fascial space the infection occupies.

Question 2

What risk factors are associated with the development of DNSI?

Answer 2

Risk factors of DNSI include

• Low level of education
• Living greater than 1 hour from a tertiary care center
• Presence of tonsils
• Streptococcus infections
• Substance abuse
• Poor dental hygiene

Question 3

Describe how the neck is organized in terms of fascial planes.

Answer 3

The neck is compartmentalized in two main divisions of fascia: the superficial cervical fascia and the deep cervical fascia.

The superficial cervical fascia includes subcutaneous tissue and envelops the muscles of facial expression. It is continuous with the superficial musculoaponeurotic system (SMAS) and extends inferiorly to involve the platysma.

The deep cervical fascia is divided into superficial, middle, and deep layers.

• The superficial layer invests parotid and submandibular glands, muscles of mastication, trapezius, sternocleidomastoid, and forms the stylomandibular ligament.
• The middle layer is composed of two divisions: the visceral division invests the larynx, pharynx, trachea, esophagus, thyroid, and parathyroid; the muscular division invests the strap muscles.
• The deep layer is composed of two divisions as well: the prevertebral divisionenvelops the paraspinal muscles and vertebrae; the alar division lies atop the prevertebral layer and covers the sympathetic trunk. The carotid sheath represents the confluence of the deep layers of the deep cervical fascia

Question 4

Identify the deep neck spaces as well as anatomic sites that contribute to the infections within these spaces.

Answer 4

Deep neck spaces can either be suprahyoid, infrahyoid, or span the entire length of the neck. It is important to understand the boundaries of the deep neck spaces because infections often follow these boundaries (or lack thereof) as they spread. DNSI typically are the result of suppuration of lymph nodes from infection at a primary anatomic site.

1. Suprahyoid:
   
   1. Peritonsillar: tonsil
   2. Parapharyngeal: tonsil, pharynx
   3. Submandibular: odontogenic, gingiva, submandibular gland
   4. Sublingual: odontogenic, gingiva, sublingual gland
2. Infrahyoid: visceral
3. Span entire length of neck
   
   1. Retropharyngeal: nasal cavity, paranasal sinuses, nasopharynx, vertebral bodies
   2. Prevertebral: hematogenous spread from vertebrae and intervertebral discs
   3. “Danger” space: parapharyngeal, retropharyngeal space infections
   4. Carotid sheath: parapharyngeal, retropharyngeal space infections

Question 5

What conditions can present in a similar fashion to DNSI?

Answer 5

Congenital anomalies can either masquerade as a DNSI or become more clinically apparent when they become infected. Thyroglossal duct cysts, lymphatic malformations, and branchial cleft cysts can rapidly increase in size and present with signs and symptoms identical to DNSI. Prior history of a mass or fullness that waxes and wanes suggests the presence of an underlying congenital lesion.

Neoplastic processes can present with rapid neck swelling and features consistent with an infectious process as well. Fevers, night sweats, and weight loss can be presenting signs of lymphoma. New neck masses in adults are more likely to be malignant when compared to pediatric patients.

Question 6

What is the “danger space”?

Answer 6

The danger space is bound by the alar fascia anteriorly and the prevertebral fascia posteriorly. It extends from the skull base to the thoracic cavity, providing an unrestricted path for spread of infection into the mediastinum, causing mediastinitis. Infections of the parapharyngeal, retropharyngeal, and prevertebral space can easily extend to this space.

Question 7

What is the most common major complication of DNSI?

Answer 7

Mediastinitis is the most common major complication of DNSI. It typically presents with tachycardia, dyspnea*, and *pleuritic chest pai*_n. Chest x-ray can demonstrate _*mediastinal widening. Further evaluation with contrast chest CT is necessary to identify fluid collections that require drainage. Broad-spectrum intravenous antibiotics, early consultation with the thoracic surgery service, and close surveillance in the intensive care unit are recommended.

Question 8

How are prevertebral space infections different from infections of other deep neck spaces?

Answer 8

Prevertebral space infections are generally the result of hematogenous seeding or contiguous spread of infection from discitis or vertebral osteomyelitis.

Gram-positive bacteria, especially Staphylococcus aureus, are the most common pathogens in these infections; anaerobes are uncommon.

Question 9

What are the most common etiologies of DNSI?

Answer 9

The etiology of DNSI varies with age.

Children: Bacterial pharyngitis and tonsillitis with resultant suppuration of parapharyngeal, retropharyngeal, and jugulodigastric lymph nodes.

Adults: Odontogenic infections; bacteria within dental plaque erode tooth enamel to form periapical abscesses that may penetrate the mandible or maxilla to enter the deep spaces of the neck.

Other etiologies include cellulitis, trauma, foreign body, intravenous drug use, or congenital lesions such as thyroglossal duct cysts or branchial cleft anomalies.

Question 10

What are the most common pathogens causing deep neck space infections?

Answer 10

Because most of these infections are odontogenic in origin, pathogens are typically part of normal oral flora. These infections are usually polymicrobial, involving a large proportion of anaerobic bacteria, especially as the infections spread into deeper neck spaces. Common bacteria include:

• Streptococcus species
• Peptostreptococcus
• Actinomyces
• Fusobacterium
• Prevotella

More common among immunocompromised hosts, diabetics, and postoperative

• Staphylococcus aureus (including MRSA)
• Pseudomonas aeruginosa
• Other gram-negative rods

Question 11

What is the role of methicillin-resistant Staphylococcus aureus (MRSA) in deep neck space infections in the United States?

Answer 11

Streptococcal species, particularly group A streptococcus, remain the most common pathogen responsible for nonpurulent skin and soft tissue infections, such as cellulitis and erysipelas.

Purulent skin and soft tissue infections involving the head and neck (abscesses, furuncles, carbuncles, wound infections), on the other hand, are most commonly caused by S. aureus. There has been a dramatic increase in the incidence of MRSA since the early 2000s, particularly community-acquired MRSA among children. Up to 70% of pediatric neck abscesses are due to MRSA in some communities. Patients less than 16 months of age with lateral neck abscesses are 10 times more likely to have aS. aureus infection than non-S. aureus.

Question 12

What signs and symptoms are common in DNSI?

Answer 12

The most common symptoms are neck pain, fever, dysphagia, neck swelling, and odynophagia. Referred pain resulting in otalgia and odynophagia is also common.

Question 13

What are the key physical exam findings in the evaluation of a patient with DNSI?

Answer 13

A complete head and neck exam is essential in all patients with DNSI. Initial interview should devote attention to hoarseness, dyspnea, stridor, stertor, muffling or “hot potato” voice. Dysphonia should be evaluated with flexible fiber-optic laryngoscopy for possible airway compromise if the patient is stable.

Inspection and palpation of the head and neck should begin away from the primary site of infection, reserving that portion of the exam for last. Evaluation of the involved area should focus on the size of the area, presence of

• induration
• swelling or fluctuance
• any color change or cellulitic change of the overlying skin. Any cellulitic change should be marked along its periphery to permit accurate surveillance.
• Presence of crepitus suggests infection with gas-producing organisms.

Cranial neuropathies can suggest retrograde spread of infection along the valveless venous system of the midface from soft tissue, nasal cavity, or the paranasal sinus infections.

Question 14

What is trismus and why is it significant?

Answer 14

Trismus refers to the reduced ability to open the mouth. In the setting of DNSI, it is a sign of inflammation of the parapharyngeal, masseteric, pterygoid, and/or temporal spaces. While seen commonly in odontogenic infections, trismus is also seen with peritonsillar, parapharyngeal, and floor of mouth infections. Severe trismus can lead to difficulty managing secretions and cause airway compromise, presenting challenges for airway intervention should it be needed.

Question 15

How should suspected deep space neck infections be worked up?

Answer 15

Typical diagnostic workup of DNSI includes complete blood count with differential and radiographic evaluations. Atypical presentations (painless, slow growing, association with weight loss and night sweats) should raise suspicion for malignancy. Atypical infectious etiologies should be evaluated with placement of a PPD with chest x-ray, HIV testing, and titers for Bartonella henselae.

Anterior-posterior and lateral neck plain films are useful in evaluation of the retropharyngeal space (figure below). Ultrasound and computed tomography are the most common radiographic modalities employed when evaluating DNSI. Ultrasound is effective in differentiating cellulitic change from a fluid collection and can also be used for guidance to localize an abscess cavity. Computed tomography with contrast can demonstrate an abscess in the form of a hypodense focus centrally with peripheral rim enhancement.

Question 16

How can submandibular space infections be distinguished from sublingual space infections?

Answer 16

Submandibular space infections involve the area inferior to the mylohyoid muscle. They are usually the result of apical abscesses of the second or third molars. Sublingual infections, which involve the space superior to the mylohyoid muscle, on the other hand, are usually the result of infections of the mandibular incisors.

Question 17

Which DNSI pose the greatest risk to the contents of the carotid sheath?

Answer 17

The parapharyngeal and retropharyngeal spaces are adjacent to the carotid sheath. Infections of the carotid sheath may lead to complications such as Horner’s syndrome (ptosis, miosis, anhydrosis from involvement of the cervical sympathetic chain), cranial nerve palsies, carotid artery rupture, and septic phlebitis of the jugular vein. This can present with neck fullness, a pulsatile neck mass with ecchymosis, and bright red bleeding from the nose, mouth, or external auditory canal.

Question 18

What are the classic signs of peritonsillar abscess?

Answer 18

Peritonsillar abscess is a clinical diagnosis and does not typically require additional diagnostic and radiographic testing. Patients typically present with trismus, muffled voice, uvular deviation, and fullness of the soft palate.

Management of peritonsillar abscess involves surgical incision and drainage. This procedure is generally tolerated with local anesthesia alone in the clinic or emergency department in cooperative patients, typically the adolescent and adult population. Pediatric patients typically require general anesthesia for management.

Isolated peritonsillar abscess requires completion of a course of oral antibiotics following drainage. Tonsillectomy is indicated in the setting of recurrent peritonsillar abscess.

Question 19

What are the indications for surgical intervention for DNSI?

Answer 19

The indications for surgical intervention depend on the medical stability of the patient. Patients who are antibiotic naïve, do not have any airway compromise, and do not have any radiographic features of abscess formation can be managed initially with systemic antibiotic therapy. Any signs of airway compromise, lack of marked improvement after 24 to 72 hours of intravenous antibiotic therapy, or clinical or radiographic signs of abscess formation should undergo incision and drainage.

The goal of incision and drainage should including collection of culture specimens, blunt dissection into the abscess cavity, and disruptions of loculations within the abscess cavity to promote drainage. Packing is placed and removed gradually during the postoperative period to prevent reaccumulation of fluid.

Question 20

What is Lemierre’s syndrome?

Answer 20

Lemierre’s syndrome is septic thrombophlebitis of the internal jugular vein, which is usually the result of hematogenous extension through tonsillar veins. Typical symptoms of pharyngitis lead to fever, lethargy, neck pain, and swelling. Septic emboli can seed in the lungs, resulting in nodular infiltrates on chest x-ray. Contrast CT of the neck demonstrates occlusion of the internal jugular vein. Fusobacterium necrophorum is the pathogen isolated in over 90% of cultures. Metronidazole is the treatment of choice.

Question 21

What is the hallmark of Actinomyces israelii infections involving the head and neck?

Answer 21

Infections caused by this bacteria frequently cross fascial planes, forming sinus tracts that drain grainy material commonly referred to as “sulfur granules.” Actinomyces is a gram-positive, branching, facultative anaerobe. Fifty percent of cases involve the head and neck. Infections typically present as a nontender, hard, slowly progressive mass in the perimandibular area (“lumpy jaw”). Treatment is with a long-term course of penicillin or amoxicillin.

Question 22

What is Ludwig’s angina and what is its major complication?

Answer 22

Ludwig’s angina is a rapidly spreading infection of the submandibular and sublingual spaces, typically odontogenic in origin. Infection superior to the mylohyoid muscle places the patient at risk for rapid swelling of the floor of mouth and tongue, resulting in airway obstruction. Patients typically present with trismus, fever, drooling, dysphonia, and dysphagia. On exam, tense swelling of the floor of the mouth and tongue protrusion are present, which can deteriorate quickly into respiratory distress. Intubation can rapidly become difficult if not impossible. Emergent tracheostomy may be indicated in addition to antibiotics and surgical drainage.

Question 23

What empiric antibiotic regimens are appropriate for DNSI?

Answer 23

Empiric antibiotics should be administered parenterally and have activity againstStreptococcus species and oral anaerobes. Appropriate cultures should be obtained if possible prior to initiation of any antimicrobial therapy. Penicillin G plus metronidazole or ampicillin-sulbactam are good choices. For patients who are allergic to penicillin, clindamycin, moxifloxacin, levofloxacin plus metronidazole, or ciprofloxacin plus metronidazole may be used.

A complete course of antimicrobial therapy is typically 10 to 14 days. Marked clinical improvement should be observed prior to conversion from intravenous to oral therapy.

Question 24

What is the most common cause of chronic unilateral regional lymphadenopathy in children?

Answer 24

Cat-scratch disease (CSD) presents as lymphadenopathy from infection by Bartonella henselae, typically several weeks after inoculation. A history of cat exposure is present in most patients. Lymphadenopathy typically resolves within 2 months but can last up to a year. Early treatment (within the first 30 days) with azithromycin for 5 days demonstrated significant decrease in lymph node volume while delayed treatment (after 30 days) demonstrated no change in rate of resolution. Surgical treatment is reserved for persistent discomfort, suppuration, and diagnostic purposes.

Question 25

Describe the typical presentation of cervical lymphadenitis caused by atypical mycobacterial infection.

Answer 25

Atypical mycobacterial infections typically present with firm, painless lymphadenopathy that typically does not respond to antibiotic therapy. The infectious process becomes more superficial in time, resulting in violaceous change of the overlying skin, resulting in drainage and scarring. Natural resolution occurs over a period of months to years. Medical management consists of long-term antibiotic therapy accompanied with surgical excision to prevent skin breakdown and unfavorable scarring.

Question 26

What is the most common manifestation of tuberculosis of the head and neck?

Answer 26

Scrofula is tuberculous lymphadenitis of the cervical region. It typically presents as a unilateral, painless, firm mass without fevers or other systemic symptoms. Diagnosis is via biopsy with culture. Treatment includes complete excision of the lymph node, in addition to antimycobacterial therapy.

Question 27

Discuss the risk factors and typical presentation of necrotizing fasciitis.

Answer 27

Necrotizing fasciitis is a rapidly progressive DNSI of the fascial planes that typically occurs in immunosuppressed patients (diabetes, chronic illness, patients undergoing chemotherapy, malnutrition) and presents with pain disproportionate with physical exam. Gas-forming bacteria can produce crepitus and gas bubbles may be seen on imaging within the soft tissues. Progression of disease is rapid; early medical management with broad-spectrum IV antibiotics coupled with aggressive surgical debridement of infected tissue is required.