CHAPTER 80 Peritonsillar Abscess Drainage

Peritonsillar abscess, an infection in the space between the palatine tonsil and the pharyngeal constrictors, is the most common deep infection or abscess of the head and neck. Approximately 45,000 cases of peritonsillar abscess occur annually in the United States, usually in patients in the second or third decade of life; it rarely occurs in immunocompetent children younger than 6 years of age. Symptoms include fever, malaise, severe sore throat, trismus, odynophagia, and dysphagia with drooling. The patient may be dehydrated from a lack of oral intake. Pain is often referred to the ear, and the patient may have a voice with muffled resonance known as a “hot potato” voice. Signs of peritonsillar abscess include nonexudative pharyngitis in the majority of cases, marked edema of the soft palate, and a fluctuant fullness of the tonsil, which is covered superiorly by a shiny membrane. The classic sign is deflection of the swollen uvula to the opposite side (Fig. 80-1). There is often inferior and medial displacement of the affected tonsil. Tender cervical adenopathy is usually present.

Figure 80-1 Peritonsillar abscess on patient’s right side. Note fluctuance, lack of exudate on tonsil, soft palate edema, and deviation of uvula to the opposite side.

The local anatomy must be understood before attempting to aspirate or drain a peritonsillar abscess. The palatine tonsils lie between the palatoglossal and palatopharyngeal arches. These two pillars form the anterior and posterior borders of the tonsil. The surface of each tonsil has a covering of mucosa with an irregular number of indentations known as tonsillar crypts. Beneath the mucosa, each tonsil is surrounded by a fibrous capsule. A peritonsillar abscess is a collection of pus between the fibrous capsule of the tonsil and the superior constrictor muscle of the pharynx, which forms the lateral wall of the tonsil. Progression of pus formation and lateral extension of cellulitis irritate the surrounding musculature, particularly the internal pterygoids, resulting in spasm and trismus. It is also important to note for this procedure that the internal carotid artery lies approximately 2.5 cm posterolateral to the tonsil and that the facial artery lies lateral to the tonsil.

Historically, it was thought that a peritonsillar abscess developed as a progression of an acute exudative tonsillitis. Currently, a peritonsillar abscess is thought to originate in Weber’s salivary glands, which are found in a space just above the tonsil known as the supratonsillar fossa. Weber’s salivary glands are a group of about 20 mucous salivary glands that assist with digestion of food particles trapped in the tonsillar crypts. They are connected to the palatine tonsil by a duct that extends to the surface of the tonsil. Supporting the theory that Weber’s glands are involved in the pathogenesis of peritonsillar abscess are the facts that a peritonsillar abscess can occur after tonsillectomy, even while the patient is on appropriate antibiotics, and the majority of abscesses are found in the superior pole of the palatine tonsil. Only 20% of abscesses are found in the mid-tonsil, and only 10% occupy the lower pole.

A peritonsillar abscess is usually polymicrobial. The most common aerobic organisms are Streptococcus pyogenes (group A beta-hemolytic Streptococcus) and Staphylococcus aureus. The most common anaerobes are Bacteroides and Fusobacterium. Throat cultures are of no benefit, and cultures from the aspirate have rarely been found to be helpful for selection of antibiotics.

The differential diagnosis of peritonsillar abscess includes unilateral tonsillitis, peritonsillar cellulitis, neoplasm, retropharyngeal abscess, leukemia, herpes simplex tonsillitis, infectious mononucleosis, foreign body aspiration, aneurysm of the internal carotid artery, and retromolar abscess. The most common entity that is confused with peritonsillar abscess is peritonsillar cellulitis. Peritonsillar cellulitis has the same symptoms, and perhaps similar physical findings, but because there is no pus between the tonsil and the lateral muscles, there is no fluctuance in the peritonsillar area. Ultrasonography may help distinguish between cellulitis and abscess, noninvasively. However, intraoral ultrasonography requires a skilled and experienced sonographer and the examination may be limited by trismus. Intraoral ultrasonography is probably most useful for locating the abscess when aspiration or incision and drainage is unsuccessful. Transcutaneous ultrasonography can also be performed by placing the transducer over the submandibular gland and scanning the tonsillar area, but there is a loss in the resolution of the image because of the distance from the transducer, so this is rarely used. Computed tomography (CT) is occasionally helpful. The CT should be done with contrast and may be helpful for ruling out an extension of the abscess.

The initial treatment of all patients with peritonsillar abscess should include adequate pain relief, hydration, and antibiotics. There is no consensus on choice of antibiotics. Penicillin, clindamycin, or cephalosporins are all reasonable as a first choice. Use of oral penicillin in doses of 500 mg four times daily has resulted in reasonable cure rates. Some clinicians add metronidazole if the clinical response in 24 hours is less than expected. Other clinicians advocate combining steroids with antibiotics. A recent study of rural field hospitals in the Indian Health Service suggested that high-dose steroids combined with cephalosporins, intravenous hydration, and analgesia were effective in reducing the number of patients needing to be air-evacuated from remote locations (see Lamkin and Portt, 2006).

Historically, the surgical treatment of peritonsillar abscess has been either abscess tonsillectomy or incision and drainage. If untreated, the abscess can rupture, possibly resulting in laryngeal aspiration, pneumonia, sepsis, or death. An untreated abscess can also spread locally or hematogenously, causing extensive local infection or even meningitis. Patients with a peritonsillar abscess and a history of three episodes of tonsillitis in the past year should probably be sent for an abscess tonsillectomy. However, for those patients without recurrent tonsillitis, there is growing evidence that needle aspiration is the treatment of choice. Needle aspiration has been shown to have an 85% to 100% success rate. Of those patients who respond initially, only 10% will have a recurrence. A second needle aspiration should also have a high success rate. Patients who fail a second or third needle aspiration should probably have an abscess tonsillectomy. (Even those patients who respond to a third aspiration should probably have a tonsillectomy, especially if this is the third infection in a year; see Chapter 83, Tonsillectomy and Adenoidectomy). The small percentage of patients whose abscess fails to resolve with a needle aspiration should probably have an incision and drainage procedure or be referred to an otolaryngologist to rule out a possible pterygomaxillary space abscess. An algorithm for the management of peritonsillar abscess is shown in Figure 80-2. Considering that the incision and drainage technique is now typically reserved for more difficult cases, it is not surprising that the recurrence rate is slightly higher than in the past, ranging from 6% to 24%.

Figure 80-2 Algorithm for management of peritonsillar abscess. ENT, ear, nose, and throat; I&D, incision and drainage.

Needle aspiration does have some drawbacks. It is painful, invasive, and performed somewhat blindly. A series of 12 patients evaluated by Haeggstrom and associates demonstrated that abscesses were located within 4 to 25 mm from the carotid artery. In addition, needle aspiration samples only one area in the tonsillar fossa and may require repeated attempts. From 12% to 24% of abscesses are missed on the first aspiration attempt. However, it is relatively simple to perform, even by those with little experience and who are not ear, nose, and throat specialists, and it does not require expensive or specialized equipment. A study performed in 1980 (Herzon and Aldridge) on the efficacy of needle aspiration showed that 80% of aspirations were performed by interns and 20% by emergency medicine specialists. Successful aspiration or incision and drainage may also help the patient avoid a hospitalization.

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