Deep neck infections are usually extensions of
infection from other primary sites, most often within the pharynx or oral
cavity. Many of these infections are life-threatening but are difficult to
detect at early stages when they may be more easily managed. Three of the most clinically
relevant spaces in the neck are the submandibular (and sublingual) space, the
lateral pharyngeal (or parapharyngeal) space, and the retropharyngeal space.
These spaces communicate with one another and with other important structures
in the head, neck, and thorax, providing infections with easy access to areas
including the mediastinum, carotid sheath, skull base, and meninges. Once
infection reaches these sensitive areas, mortality rates can be as high as 20
to 50%.
Infection of the submandibular and/or sublingual space
typically originates from an infected or recently extracted lower tooth. The
result is the severe, life-threatening infection referred to as Ludwig’s
angina. Lateral pharyngeal (or parapharyngeal) space infection is most often a
complication of common infections of the oral cavity and upper respiratory
tract, including tonsillitis, peritonsillar abscess, pharyngitis, mastoiditis,
or periodontal infection. This space, located deep to the lateral wall of the
pharynx, contains a number of sensitive structures, including the carotid
artery, internal jugular vein, cervical sympathetic chain, and portions of
cranial nerves IX through XII; at its distal end, it opens into the posterior mediastinum.
Involvement of this space with infection can therefore be rapidly fatal.
Examination may reveal some tonsillar displacement, trismus, and neck rigidity,
but lateral pharyngeal wall swelling can easily be missed. The diagnosis can be
confirmed by CT. Treatment consists of airway management, operative drainage of
fluid collections, and at least a 10-day course of intravenous therapy with an
antibiotic active against streptococci and oral anaerobes (e.g.,
ampicillin/sulbactam). A particularly severe form of this infection involving the
components of the carotid sheath, called postanginal septicemia (or Lemierre’s
disease), is described above (“Oral Infections”). Infection of the
retropharyngeal space can also be extremely dangerous, as this space runs
posterior to the pharynx from the skull base to the superior mediastinum.
Infections in this space are more common in children <5years old because of the presence of several small
retropharyngeal lymph nodes that typically atrophy by the age of 4 years.
Infection is usually a consequence of extension from another site of infection,
most commonly acute pharyngitis. Other sources include otitis media,
tonsillitis, dental infections, Ludwig’s angina, and anterior extension of vertebral
osteomyelitis. Retropharyngeal space infection can also follow penetrating
trauma to the posterior pharynx (e.g., from an endoscopic procedure).
Infections are commonly polymicrobial, with a mixture of aerobes and anaerobes;
group A _-hemolytic streptococci and S. aureus are the most common pathogens. Tuberculosis was a frequent
cause in the past but now is rarely seen in the United States. Patients with
retropharyngeal abscess typically present with sore throat, fever, dysphagia,
and neck pain and are often drooling because of difficulty and pain with
swallowing. Examination may reveal tender cervical adenopathy, neck swelling,
and diffuse erythema and edema of the posterior pharynx as well as a bulge in
the posterior pharyngeal wall, although the latter may not be obvious on
routine inspection. A soft tissue mass is usually demonstrable by lateral neck
radiography or CT. Because of the risk of airway obstruction, treatment begins with
securing of the airway, which is followed by a combination of surgical drainage
and intravenous antibiotic administration. Initial empirical therapy should
cover streptococci, oral anaerobes, and S. aureus; ampicillin/sulbactam, clindamycin alone, or clindamycin plus ceftriaxone
is usually effective. Complications occur primarily as a result of extension to
other areas, including rupture into the posterior pharynx, which may lead to
aspiration pneumonia and empyema. Extension may also occur to the lateral
pharyngeal space and mediastinum, resulting in mediastinitis and pericarditis,
or into nearby major blood vessels. All these events are associated with a high
mortality rate.
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