CC
A 25-year-old male presents to the emergency department with the complaint that “my throat is swollen, and I cannot swallow.”
HPI
Approximately 1 week earlier, the patient began to experience acute pain localized to the posterior mandibular molars, with subsequent development of edema in his left posterior oropharynx 3 days later. He reports the onset of limited mouth opening, progressively worsening dysphagia (difficulty swallowing), and globus (sensation of a lump in the throat) that eventually prompted him to seek care. (Trismus and dysphagia have been shown to be significant indicators of severe odontogenic infection.) He has difficulty swallowing his secretions, either drooling or spitting them out. (This is an important clinical note because it denotes life-threatening oropharyngeal edema.) He explains that he has had minimal oral intake with the onset of fever and chills. At this time, he does not report any difficulty with breathing, but he feels more comfortable when sitting up (an important clinical sign of dangerous oropharyngeal edema). The patient has a muffled, “hot potato” voice (secondary to supraglottic edema). Multiple studies have found that pain, fever, trismus, odynophagia, dysphagia, reduced oral intake, and raised floor of mouth are significantly associated with patients requiring hospital admission.
Dental infections have become the most common cause of deep neck infections in the Western world, involving the masticator, parapharyngeal, and submandibular spaces. More than 50% of patients presenting with infection involving these spaces have an odontogenic cause, making oral and maxillofacial surgeons a preferred provider of surgical care for this group. In addition, Seppanen et al. reports that despite antibiotic advancements, the incidence of odontogenic infections has continued to increase. Many odontogenic infections arise because of carious decay. Using a caries risk assessment tool such as Caries Management by Risk Assessment (CAMBRA) is very beneficial for all dental providers to use during their clinical examinations. This approach assesses each patient for their risk of developing dental caries that can then lead to decay. Based on the assessment, the provider can suggest interventions and lifestyle changes that can stop or reverse the disease course and prevent patients from developing decay and subsequent odontogenic infections.
PMHX/PDHX/medications/allergies/SH/FH
The past medical and dental histories are unremarkable. The patient lives in a shelter and does not currently hold a job. (Although masticator space infections can be seen in individuals of all socioeconomic strata, the condition is far more predominant in the population with less access to health care, including frequent dental examinations.)
Despite the lack of coexisting medical diseases in this patient, it is important to consider any conditions that impair the immune system, such as HIV/AIDS, diabetes mellitus, chronic corticosteroid therapy, or chemotherapy. Patients should be questioned about risk factors for HIV infection and appropriately tested as needed. Masticator space infections can have very aggressive behavior in the face of immunosuppression. Patients with HIV presenting with deep space neck infections are more likely to develop Ludwig’s angina, leading to airway obstruction as well as other complications, including sepsis, mediastinitis, jugular vein thrombosis, and pneumonia. They also often have longer hospital stays and higher mortality rates. The factors in this group most associated with complications are being 55 years of age or older and having a CD4 count of 350 cells/mm 3 or less.
Examination
General. The patient is a thin and unkempt-appearing male with a noticeable pungent odor (indicative of neglect to health and hygiene). The patient is not in respiratory distress. (It is important to assess the need for advanced airway intervention immediately upon examination.) He appears anxious, sitting up holding an emesis basin to catch his secretions as they drool from his mouth (difficulty maintaining secretions).
Vital signs. His blood pressure is 104/68 mm Hg (hypotension secondary to dehydration), heart rate is 116 bpm (tachycardia secondary to hypotension and fever), respirations are 20 breaths per minute, and temperature is 39.2°C (febrile), with an oxygen saturation of 98% on room air.
Maxillofacial. There is significant swelling and induration of the left side extending from the level of the hyoid bone anterior to the sternocleidomastoid to the zygomatic arch. Cranial nerves II through XII are grossly intact. The pupils are equal, round, and reactive to light and accommodation, with no proptosis or ptosis of the eyelids. (These would be suggestive of cavernous sinus involvement.)
Intraoral. Maximal interincisal opening is 17 mm (trismus) ( Fig. 25.1 A). The floor of the mouth is soft (sublingual space not involved). The patient is able to protrude his tongue past the vermillion–cutaneous border of the upper lip. (The ability to protrude the tongue past the vermilion border of the upper lip is a reliable sign that the sublingual space is not severely involved.) There is significant fluctuant swelling of the left oropharynx toward the right tonsillar area, with the tip of the uvula touching the right pharyngeal wall ( Fig. 25.1 B). The operculum overlying the partially bony impacted left mandibular third molar is edematous, erythematous, and tender to palpation, with no obvious purulent discharge. (Mandibular third molars are a common cause of lateral pharyngeal infections.) Mucous membranes of the buccal mucosa are dry (secondary to dehydration).
Imaging
Before any further diagnostic imaging, the treating surgeon must decide whether the patient (and the airway) is stable enough for obtaining further studies, or arrangements should be made to proceed directly to the operating room (OR) and establish a secure airway (endotracheal or nasotracheal intubation, tracheostomy, cricothyrotomy). Any possibility of acute respiratory obstruction should prompt the surgeon to proceed directly to the OR. Imaging studies can be safely obtained to guide further treatment at a later time.
When available, a panoramic radiograph is an important imaging study for evaluation of suspected odontogenic infections. It provides an excellent overview of the mandible and maxilla and serves as a screening tool for evaluation of the dentition. Also, in patients with trismus, other dental radiographs may be difficult to obtain. Because mandibular third molars are the most common odontogenic cause of parapharyngeal space infections, this radiograph becomes necessary to evaluate the third molars. In addition, it delineates the relationship to adjacent structures, such as the inferior alveolar canal, and other possible bony pathology.
The combination of contrast-enhanced computed tomography (CT) scans and clinical examination has the highest sensitivity and specificity in the diagnosis of deep neck infections. The use of contrast improves the ability to identify the hyperemic capsule of a longstanding abscess. (Abscesses are seen as discrete, hypodense areas that show an enhancing peripheral rim with use of intravenous [IV] contrast material.) In general, most radiologists interpret hypodense areas without ring enhancement to represent cellulitis or edema. However, studies have shown that, when drained, approximately 45% of hypodense areas without ring enhancement yield pus. In a study by Miller and associates, a hypodense area of greater than 2 mL without ring enhancement yielded purulence at the time of surgery. In the same study, CT scans were able to correctly differentiate cellulitis from an abscess in 85% of deep neck space (lateral and retropharyngeal) infections.
Computed tomography also provides important information regarding the details of adjacent anatomic structures, such as the integrity of the airway, tracheal deviation, and the proximity of vascular structures (the carotid sheath). Airway deviation and the risk of rupture of the pharyngeal abscess during intubation are important factors in determining the choice of technique to secure the airway.
Magnetic resonance imaging (MRI) is also a useful imaging modality for soft tissue evaluation. Compared with CT, advantages of MRI include superior anatomic multiplanar display, high soft tissue contrast, fewer artifacts from dental amalgam, and lack of ionizing radiation. However, MRI is more difficult and slower to perform on an emergency basis and is more costly, and claustrophobia may preclude examination in some patients. MRI, when possible, has been shown to be superior in the assessment of deep neck infections.
Ultrasonography has shown some benefit in differentiating cellulitis from an abscess in superficial locations, but the use of this modality as a sole imaging technique for deep neck infection is in its infancy. Ultrasonography imaging can detect edema, subcutaneous emphysema, and perifacial fluid collection. The ultrasound probe can be placed intraorally, although in the setting of an acute infection and trismus, this can be difficult. An abscess is seen as an echo-free cavity with an irregular, well-defined circumference. A recent study by Costa et al. presents an ultrasonography technique that uses a transcervical probe to evaluate deep neck infections after drainage to determine the locations of the drains inside the collection area as well as adjacent edema. This approach allows for more frequent bedside assessments of patient infection resolution than CT or MRI.
In the current patient, the airway appeared clinically stable, and a panoramic radiograph demonstrated a carious and partially bony impacted left mandibular third molar. A CT scan with contrast demonstrated significant swelling of the lateral pharyngeal area and deviation of the airway ( Fig. 25.2 ). Large rim-enhancing hypodense areas consistent with pus are seen on the left lateral masticator and lateral pharyngeal (anterior compartment) spaces.
Labs
A complete blood count and a basic metabolic panel should be obtained during the initial evaluation of deep neck space infections. The white blood cell (WBC) count is an indicator of the severity of the systemic response to the infection and can be obtained periodically to monitor the progression of infection. (Caution should be exercised in interpretation of this value in a patient who is at high risk for undiagnosed AIDS because the WBC count may appear within the normal range secondary to the inability to mount an adequate immune response.)
The serum creatinine and blood urea nitrogen (BUN) levels should be obtained before contrast material is used for imaging. Contrast material has been known to cause contrast-associated nephropathy. The condition is defined as an increase in serum creatinine greater than 25% from baseline or an increase greater than 0.5 mg/dL within 48 hours of contrast exposure in the absence of other causes. Risk factors for the development of contrast-associated nephropathy are summarized in Box 25.1 . In the presence of risk factors, renal function should be carefully monitored, and a baseline serum creatinine concentration should be obtained before and within 48 to 72 hours after the procedure.
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Preexisting renal disease
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Diabetes
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Volume of contrast dye used
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Dehydration
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Congestive heart failure
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Advanced age
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Presence of nephrotoxic drugs (NSAIDs, ACEIs)
The WBC count for the current patient was 18,500 cells/mm 3 ; the differential diagnosis included 80% polymorphonucleocytes with a shift to the left (indicative of an acute inflammatory process).
Serum chemistries showed a sodium level of 150 mEq/dL (hypovolemic hypernatremia caused by dehydration), BUN of 48 mg/dL, and creatinine of 1.1 mg/dL (prerenal azotemia consistent with dehydration).
Assessment
Deep neck infection involving the anterior compartment of the left lateral pharyngeal space (LPS) with significant upper airway deviation and edema and left medial and lateral masticator space infections secondary to an impacted mandibular third molar, complicated by dehydration and potential onset of sepsis.
Treatment
Successful treatment of fascial space infections should include the following:
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Surgical drainage of an abscess or, in select cases, drainage of cellulitis
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Identification and removal of the source of infection (the tooth, in cases of odontogenic etiology)
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Administration of antibiotics (guided by culture and sensitivity when possible)
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Optimization of host nutritional and immune status
Antimicrobial therapy can abort abscess formation if administered at an early stage of infection. However, after an abscess has formed, antimicrobial therapy is more effective in conjunction with adequate surgical drainage.
Impending airway obstruction may require immediate airway management (see discussions of Ludwig’s angina, earlier in this chapter, and emergent surgical airway in Chapter 24 ). Maintaining spontaneous ventilation and airway patency is critical in patients with a compromised airway. Even a small dose of a respiratory depressant may change an apparently controlled situation into an emergent one, especially in the presence of a fatiguing patient. Morbidity or death caused by the loss of an airway is still reported. Available options include endotracheal intubation versus establishment of a surgical airway. The advantages and disadvantages of these methods are summarized in Table 25.1 . Consideration should be given to endotracheal intubation using an awake fiberoptic technique. This requires a skilled anesthesiologist and patient cooperation and can be time-consuming.
